Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6

[linux-2.6] / fs / proc / base.c

/*
 *  linux/fs/proc/base.c
 *
 *  Copyright (C) 1991, 1992 Linus Torvalds
 *
 *  proc base directory handling functions
 *
 *  1999, Al Viro. Rewritten. Now it covers the whole per-process part.
 *  Instead of using magical inumbers to determine the kind of object
 *  we allocate and fill in-core inodes upon lookup. They don't even
 *  go into icache. We cache the reference to task_struct upon lookup too.
 *  Eventually it should become a filesystem in its own. We don't use the
 *  rest of procfs anymore.
 *
 *
 *  Changelog:
 *  17-Jan-2005
 *  Allan Bezerra
 *  Bruna Moreira <bruna.moreira@indt.org.br>
 *  Edjard Mota <edjard.mota@indt.org.br>
 *  Ilias Biris <ilias.biris@indt.org.br>
 *  Mauricio Lin <mauricio.lin@indt.org.br>
 *
 *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
 *
 *  A new process specific entry (smaps) included in /proc. It shows the
 *  size of rss for each memory area. The maps entry lacks information
 *  about physical memory size (rss) for each mapped file, i.e.,
 *  rss information for executables and library files.
 *  This additional information is useful for any tools that need to know
 *  about physical memory consumption for a process specific library.
 *
 *  Changelog:
 *  21-Feb-2005
 *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
 *  Pud inclusion in the page table walking.
 *
 *  ChangeLog:
 *  10-Mar-2005
 *  10LE Instituto Nokia de Tecnologia - INdT:
 *  A better way to walks through the page table as suggested by Hugh Dickins.
 *
 *  Simo Piiroinen <simo.piiroinen@nokia.com>:
 *  Smaps information related to shared, private, clean and dirty pages.
 *
 *  Paul Mundt <paul.mundt@nokia.com>:
 *  Overall revision about smaps.
 */

#include <asm/uaccess.h>

#include <linux/errno.h>
#include <linux/time.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/capability.h>
#include <linux/file.h>
#include <linux/string.h>
#include <linux/seq_file.h>
#include <linux/namei.h>
#include <linux/namespace.h>
#include <linux/mm.h>
#include <linux/smp_lock.h>
#include <linux/rcupdate.h>
#include <linux/kallsyms.h>
#include <linux/mount.h>
#include <linux/security.h>
#include <linux/ptrace.h>
#include <linux/seccomp.h>
#include <linux/cpuset.h>
#include <linux/audit.h>
#include <linux/poll.h>
#include "internal.h"

/* NOTE:
 *      Implementing inode permission operations in /proc is almost
 *      certainly an error.  Permission checks need to happen during
 *      each system call not at open time.  The reason is that most of
 *      what we wish to check for permissions in /proc varies at runtime.
 *
 *      The classic example of a problem is opening file descriptors
 *      in /proc for a task before it execs a suid executable.
 */

/*
 * For hysterical raisins we keep the same inumbers as in the old procfs.
 * Feel free to change the macro below - just keep the range distinct from
 * inumbers of the rest of procfs (currently those are in 0x0000--0xffff).
 * As soon as we'll get a separate superblock we will be able to forget
 * about magical ranges too.
 */

#define fake_ino(pid,ino) (((pid)<<16)|(ino))

enum pid_directory_inos {
        PROC_TGID_INO = 2,
        PROC_TGID_TASK,
        PROC_TGID_STATUS,
        PROC_TGID_MEM,
#ifdef CONFIG_SECCOMP
        PROC_TGID_SECCOMP,
#endif
        PROC_TGID_CWD,
        PROC_TGID_ROOT,
        PROC_TGID_EXE,
        PROC_TGID_FD,
        PROC_TGID_ENVIRON,
        PROC_TGID_AUXV,
        PROC_TGID_CMDLINE,
        PROC_TGID_STAT,
        PROC_TGID_STATM,
        PROC_TGID_MAPS,
        PROC_TGID_NUMA_MAPS,
        PROC_TGID_MOUNTS,
        PROC_TGID_MOUNTSTATS,
        PROC_TGID_WCHAN,
#ifdef CONFIG_MMU
        PROC_TGID_SMAPS,
#endif
#ifdef CONFIG_SCHEDSTATS
        PROC_TGID_SCHEDSTAT,
#endif
#ifdef CONFIG_CPUSETS
        PROC_TGID_CPUSET,
#endif
#ifdef CONFIG_SECURITY
        PROC_TGID_ATTR,
        PROC_TGID_ATTR_CURRENT,
        PROC_TGID_ATTR_PREV,
        PROC_TGID_ATTR_EXEC,
        PROC_TGID_ATTR_FSCREATE,
        PROC_TGID_ATTR_KEYCREATE,
        PROC_TGID_ATTR_SOCKCREATE,
#endif
#ifdef CONFIG_AUDITSYSCALL
        PROC_TGID_LOGINUID,
#endif
        PROC_TGID_OOM_SCORE,
        PROC_TGID_OOM_ADJUST,
        PROC_TID_INO,
        PROC_TID_STATUS,
        PROC_TID_MEM,
#ifdef CONFIG_SECCOMP
        PROC_TID_SECCOMP,
#endif
        PROC_TID_CWD,
        PROC_TID_ROOT,
        PROC_TID_EXE,
        PROC_TID_FD,
        PROC_TID_ENVIRON,
        PROC_TID_AUXV,
        PROC_TID_CMDLINE,
        PROC_TID_STAT,
        PROC_TID_STATM,
        PROC_TID_MAPS,
        PROC_TID_NUMA_MAPS,
        PROC_TID_MOUNTS,
        PROC_TID_MOUNTSTATS,
        PROC_TID_WCHAN,
#ifdef CONFIG_MMU
        PROC_TID_SMAPS,
#endif
#ifdef CONFIG_SCHEDSTATS
        PROC_TID_SCHEDSTAT,
#endif
#ifdef CONFIG_CPUSETS
        PROC_TID_CPUSET,
#endif
#ifdef CONFIG_SECURITY
        PROC_TID_ATTR,
        PROC_TID_ATTR_CURRENT,
        PROC_TID_ATTR_PREV,
        PROC_TID_ATTR_EXEC,
        PROC_TID_ATTR_FSCREATE,
        PROC_TID_ATTR_KEYCREATE,
        PROC_TID_ATTR_SOCKCREATE,
#endif
#ifdef CONFIG_AUDITSYSCALL
        PROC_TID_LOGINUID,
#endif
        PROC_TID_OOM_SCORE,
        PROC_TID_OOM_ADJUST,

        /* Add new entries before this */
        PROC_TID_FD_DIR = 0x8000,       /* 0x8000-0xffff */
};

/* Worst case buffer size needed for holding an integer. */
#define PROC_NUMBUF 10

struct pid_entry {
        int type;
        int len;
        char *name;
        mode_t mode;
};

#define E(type,name,mode) {(type),sizeof(name)-1,(name),(mode)}

static struct pid_entry tgid_base_stuff[] = {
        E(PROC_TGID_TASK,      "task",    S_IFDIR|S_IRUGO|S_IXUGO),
        E(PROC_TGID_FD,        "fd",      S_IFDIR|S_IRUSR|S_IXUSR),
        E(PROC_TGID_ENVIRON,   "environ", S_IFREG|S_IRUSR),
        E(PROC_TGID_AUXV,      "auxv",    S_IFREG|S_IRUSR),
        E(PROC_TGID_STATUS,    "status",  S_IFREG|S_IRUGO),
        E(PROC_TGID_CMDLINE,   "cmdline", S_IFREG|S_IRUGO),
        E(PROC_TGID_STAT,      "stat",    S_IFREG|S_IRUGO),
        E(PROC_TGID_STATM,     "statm",   S_IFREG|S_IRUGO),
        E(PROC_TGID_MAPS,      "maps",    S_IFREG|S_IRUGO),
#ifdef CONFIG_NUMA
        E(PROC_TGID_NUMA_MAPS, "numa_maps", S_IFREG|S_IRUGO),
#endif
        E(PROC_TGID_MEM,       "mem",     S_IFREG|S_IRUSR|S_IWUSR),
#ifdef CONFIG_SECCOMP
        E(PROC_TGID_SECCOMP,   "seccomp", S_IFREG|S_IRUSR|S_IWUSR),
#endif
        E(PROC_TGID_CWD,       "cwd",     S_IFLNK|S_IRWXUGO),
        E(PROC_TGID_ROOT,      "root",    S_IFLNK|S_IRWXUGO),
        E(PROC_TGID_EXE,       "exe",     S_IFLNK|S_IRWXUGO),
        E(PROC_TGID_MOUNTS,    "mounts",  S_IFREG|S_IRUGO),
        E(PROC_TGID_MOUNTSTATS, "mountstats", S_IFREG|S_IRUSR),
#ifdef CONFIG_MMU
        E(PROC_TGID_SMAPS,     "smaps",   S_IFREG|S_IRUGO),
#endif
#ifdef CONFIG_SECURITY
        E(PROC_TGID_ATTR,      "attr",    S_IFDIR|S_IRUGO|S_IXUGO),
#endif
#ifdef CONFIG_KALLSYMS
        E(PROC_TGID_WCHAN,     "wchan",   S_IFREG|S_IRUGO),
#endif
#ifdef CONFIG_SCHEDSTATS
        E(PROC_TGID_SCHEDSTAT, "schedstat", S_IFREG|S_IRUGO),
#endif
#ifdef CONFIG_CPUSETS
        E(PROC_TGID_CPUSET,    "cpuset",  S_IFREG|S_IRUGO),
#endif
        E(PROC_TGID_OOM_SCORE, "oom_score",S_IFREG|S_IRUGO),
        E(PROC_TGID_OOM_ADJUST,"oom_adj", S_IFREG|S_IRUGO|S_IWUSR),
#ifdef CONFIG_AUDITSYSCALL
        E(PROC_TGID_LOGINUID, "loginuid", S_IFREG|S_IWUSR|S_IRUGO),
#endif
        {0,0,NULL,0}
};
static struct pid_entry tid_base_stuff[] = {
        E(PROC_TID_FD,         "fd",      S_IFDIR|S_IRUSR|S_IXUSR),
        E(PROC_TID_ENVIRON,    "environ", S_IFREG|S_IRUSR),
        E(PROC_TID_AUXV,       "auxv",    S_IFREG|S_IRUSR),
        E(PROC_TID_STATUS,     "status",  S_IFREG|S_IRUGO),
        E(PROC_TID_CMDLINE,    "cmdline", S_IFREG|S_IRUGO),
        E(PROC_TID_STAT,       "stat",    S_IFREG|S_IRUGO),
        E(PROC_TID_STATM,      "statm",   S_IFREG|S_IRUGO),
        E(PROC_TID_MAPS,       "maps",    S_IFREG|S_IRUGO),
#ifdef CONFIG_NUMA
        E(PROC_TID_NUMA_MAPS,  "numa_maps",    S_IFREG|S_IRUGO),
#endif
        E(PROC_TID_MEM,        "mem",     S_IFREG|S_IRUSR|S_IWUSR),
#ifdef CONFIG_SECCOMP
        E(PROC_TID_SECCOMP,    "seccomp", S_IFREG|S_IRUSR|S_IWUSR),
#endif
        E(PROC_TID_CWD,        "cwd",     S_IFLNK|S_IRWXUGO),
        E(PROC_TID_ROOT,       "root",    S_IFLNK|S_IRWXUGO),
        E(PROC_TID_EXE,        "exe",     S_IFLNK|S_IRWXUGO),
        E(PROC_TID_MOUNTS,     "mounts",  S_IFREG|S_IRUGO),
#ifdef CONFIG_MMU
        E(PROC_TID_SMAPS,      "smaps",   S_IFREG|S_IRUGO),
#endif
#ifdef CONFIG_SECURITY
        E(PROC_TID_ATTR,       "attr",    S_IFDIR|S_IRUGO|S_IXUGO),
#endif
#ifdef CONFIG_KALLSYMS
        E(PROC_TID_WCHAN,      "wchan",   S_IFREG|S_IRUGO),
#endif
#ifdef CONFIG_SCHEDSTATS
        E(PROC_TID_SCHEDSTAT, "schedstat",S_IFREG|S_IRUGO),
#endif
#ifdef CONFIG_CPUSETS
        E(PROC_TID_CPUSET,     "cpuset",  S_IFREG|S_IRUGO),
#endif
        E(PROC_TID_OOM_SCORE,  "oom_score",S_IFREG|S_IRUGO),
        E(PROC_TID_OOM_ADJUST, "oom_adj", S_IFREG|S_IRUGO|S_IWUSR),
#ifdef CONFIG_AUDITSYSCALL
        E(PROC_TID_LOGINUID, "loginuid", S_IFREG|S_IWUSR|S_IRUGO),
#endif
        {0,0,NULL,0}
};

#ifdef CONFIG_SECURITY
static struct pid_entry tgid_attr_stuff[] = {
        E(PROC_TGID_ATTR_CURRENT,  "current",  S_IFREG|S_IRUGO|S_IWUGO),
        E(PROC_TGID_ATTR_PREV,     "prev",     S_IFREG|S_IRUGO),
        E(PROC_TGID_ATTR_EXEC,     "exec",     S_IFREG|S_IRUGO|S_IWUGO),
        E(PROC_TGID_ATTR_FSCREATE, "fscreate", S_IFREG|S_IRUGO|S_IWUGO),
        E(PROC_TGID_ATTR_KEYCREATE, "keycreate", S_IFREG|S_IRUGO|S_IWUGO),
        E(PROC_TGID_ATTR_SOCKCREATE, "sockcreate", S_IFREG|S_IRUGO|S_IWUGO),
        {0,0,NULL,0}
};
static struct pid_entry tid_attr_stuff[] = {
        E(PROC_TID_ATTR_CURRENT,   "current",  S_IFREG|S_IRUGO|S_IWUGO),
        E(PROC_TID_ATTR_PREV,      "prev",     S_IFREG|S_IRUGO),
        E(PROC_TID_ATTR_EXEC,      "exec",     S_IFREG|S_IRUGO|S_IWUGO),
        E(PROC_TID_ATTR_FSCREATE,  "fscreate", S_IFREG|S_IRUGO|S_IWUGO),
        E(PROC_TID_ATTR_KEYCREATE, "keycreate", S_IFREG|S_IRUGO|S_IWUGO),
        E(PROC_TID_ATTR_SOCKCREATE, "sockcreate", S_IFREG|S_IRUGO|S_IWUGO),
        {0,0,NULL,0}
};
#endif

#undef E

static int proc_fd_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
{
        struct task_struct *task = get_proc_task(inode);
        struct files_struct *files = NULL;
        struct file *file;
        int fd = proc_fd(inode);

        if (task) {
                files = get_files_struct(task);
                put_task_struct(task);
        }
        if (files) {
                /*
                 * We are not taking a ref to the file structure, so we must
                 * hold ->file_lock.
                 */
                spin_lock(&files->file_lock);
                file = fcheck_files(files, fd);
                if (file) {
                        *mnt = mntget(file->f_vfsmnt);
                        *dentry = dget(file->f_dentry);
                        spin_unlock(&files->file_lock);
                        put_files_struct(files);
                        return 0;
                }
                spin_unlock(&files->file_lock);
                put_files_struct(files);
        }
        return -ENOENT;
}

static struct fs_struct *get_fs_struct(struct task_struct *task)
{
        struct fs_struct *fs;
        task_lock(task);
        fs = task->fs;
        if(fs)
                atomic_inc(&fs->count);
        task_unlock(task);
        return fs;
}

static int get_nr_threads(struct task_struct *tsk)
{
        /* Must be called with the rcu_read_lock held */
        unsigned long flags;
        int count = 0;

        if (lock_task_sighand(tsk, &flags)) {
                count = atomic_read(&tsk->signal->count);
                unlock_task_sighand(tsk, &flags);
        }
        return count;
}

static int proc_cwd_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
{
        struct task_struct *task = get_proc_task(inode);
        struct fs_struct *fs = NULL;
        int result = -ENOENT;

        if (task) {
                fs = get_fs_struct(task);
                put_task_struct(task);
        }
        if (fs) {
                read_lock(&fs->lock);
                *mnt = mntget(fs->pwdmnt);
                *dentry = dget(fs->pwd);
                read_unlock(&fs->lock);
                result = 0;
                put_fs_struct(fs);
        }
        return result;
}

static int proc_root_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
{
        struct task_struct *task = get_proc_task(inode);
        struct fs_struct *fs = NULL;
        int result = -ENOENT;

        if (task) {
                fs = get_fs_struct(task);
                put_task_struct(task);
        }
        if (fs) {
                read_lock(&fs->lock);
                *mnt = mntget(fs->rootmnt);
                *dentry = dget(fs->root);
                read_unlock(&fs->lock);
                result = 0;
                put_fs_struct(fs);
        }
        return result;
}

#define MAY_PTRACE(task) \
        (task == current || \
        (task->parent == current && \
        (task->ptrace & PT_PTRACED) && \
         (task->state == TASK_STOPPED || task->state == TASK_TRACED) && \
         security_ptrace(current,task) == 0))

static int proc_pid_environ(struct task_struct *task, char * buffer)
{
        int res = 0;
        struct mm_struct *mm = get_task_mm(task);
        if (mm) {
                unsigned int len = mm->env_end - mm->env_start;
                if (len > PAGE_SIZE)
                        len = PAGE_SIZE;
                res = access_process_vm(task, mm->env_start, buffer, len, 0);
                if (!ptrace_may_attach(task))
                        res = -ESRCH;
                mmput(mm);
        }
        return res;
}

static int proc_pid_cmdline(struct task_struct *task, char * buffer)
{
        int res = 0;
        unsigned int len;
        struct mm_struct *mm = get_task_mm(task);
        if (!mm)
                goto out;
        if (!mm->arg_end)
                goto out_mm;    /* Shh! No looking before we're done */

        len = mm->arg_end - mm->arg_start;
 
        if (len > PAGE_SIZE)
                len = PAGE_SIZE;
 
        res = access_process_vm(task, mm->arg_start, buffer, len, 0);

        // If the nul at the end of args has been overwritten, then
        // assume application is using setproctitle(3).
        if (res > 0 && buffer[res-1] != '\0' && len < PAGE_SIZE) {
                len = strnlen(buffer, res);
                if (len < res) {
                    res = len;
                } else {
                        len = mm->env_end - mm->env_start;
                        if (len > PAGE_SIZE - res)
                                len = PAGE_SIZE - res;
                        res += access_process_vm(task, mm->env_start, buffer+res, len, 0);
                        res = strnlen(buffer, res);
                }
        }
out_mm:
        mmput(mm);
out:
        return res;
}

static int proc_pid_auxv(struct task_struct *task, char *buffer)
{
        int res = 0;
        struct mm_struct *mm = get_task_mm(task);
        if (mm) {
                unsigned int nwords = 0;
                do
                        nwords += 2;
                while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
                res = nwords * sizeof(mm->saved_auxv[0]);
                if (res > PAGE_SIZE)
                        res = PAGE_SIZE;
                memcpy(buffer, mm->saved_auxv, res);
                mmput(mm);
        }
        return res;
}


#ifdef CONFIG_KALLSYMS
/*
 * Provides a wchan file via kallsyms in a proper one-value-per-file format.
 * Returns the resolved symbol.  If that fails, simply return the address.
 */
static int proc_pid_wchan(struct task_struct *task, char *buffer)
{
        char *modname;
        const char *sym_name;
        unsigned long wchan, size, offset;
        char namebuf[KSYM_NAME_LEN+1];

        wchan = get_wchan(task);

        sym_name = kallsyms_lookup(wchan, &size, &offset, &modname, namebuf);
        if (sym_name)
                return sprintf(buffer, "%s", sym_name);
        return sprintf(buffer, "%lu", wchan);
}
#endif /* CONFIG_KALLSYMS */

#ifdef CONFIG_SCHEDSTATS
/*
 * Provides /proc/PID/schedstat
 */
static int proc_pid_schedstat(struct task_struct *task, char *buffer)
{
        return sprintf(buffer, "%lu %lu %lu\n",
                        task->sched_info.cpu_time,
                        task->sched_info.run_delay,
                        task->sched_info.pcnt);
}
#endif

/* The badness from the OOM killer */
unsigned long badness(struct task_struct *p, unsigned long uptime);
static int proc_oom_score(struct task_struct *task, char *buffer)
{
        unsigned long points;
        struct timespec uptime;

        do_posix_clock_monotonic_gettime(&uptime);
        points = badness(task, uptime.tv_sec);
        return sprintf(buffer, "%lu\n", points);
}

/************************************************************************/
/*                       Here the fs part begins                        */
/************************************************************************/

/* permission checks */
static int proc_fd_access_allowed(struct inode *inode)
{
        struct task_struct *task;
        int allowed = 0;
        /* Allow access to a task's file descriptors if it is us or we
         * may use ptrace attach to the process and find out that
         * information.
         */
        task = get_proc_task(inode);
        if (task) {
                allowed = ptrace_may_attach(task);
                put_task_struct(task);
        }
        return allowed;
}

static int proc_setattr(struct dentry *dentry, struct iattr *attr)
{
        int error;
        struct inode *inode = dentry->d_inode;

        if (attr->ia_valid & ATTR_MODE)
                return -EPERM;

        error = inode_change_ok(inode, attr);
        if (!error) {
                error = security_inode_setattr(dentry, attr);
                if (!error)
                        error = inode_setattr(inode, attr);
        }
        return error;
}

static struct inode_operations proc_def_inode_operations = {
        .setattr        = proc_setattr,
};

extern struct seq_operations mounts_op;
struct proc_mounts {
        struct seq_file m;
        int event;
};

static int mounts_open(struct inode *inode, struct file *file)
{
        struct task_struct *task = get_proc_task(inode);
        struct namespace *namespace = NULL;
        struct proc_mounts *p;
        int ret = -EINVAL;

        if (task) {
                task_lock(task);
                namespace = task->namespace;
                if (namespace)
                        get_namespace(namespace);
                task_unlock(task);
                put_task_struct(task);
        }

        if (namespace) {
                ret = -ENOMEM;
                p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
                if (p) {
                        file->private_data = &p->m;
                        ret = seq_open(file, &mounts_op);
                        if (!ret) {
                                p->m.private = namespace;
                                p->event = namespace->event;
                                return 0;
                        }
                        kfree(p);
                }
                put_namespace(namespace);
        }
        return ret;
}

static int mounts_release(struct inode *inode, struct file *file)
{
        struct seq_file *m = file->private_data;
        struct namespace *namespace = m->private;
        put_namespace(namespace);
        return seq_release(inode, file);
}

static unsigned mounts_poll(struct file *file, poll_table *wait)
{
        struct proc_mounts *p = file->private_data;
        struct namespace *ns = p->m.private;
        unsigned res = 0;

        poll_wait(file, &ns->poll, wait);

        spin_lock(&vfsmount_lock);
        if (p->event != ns->event) {
                p->event = ns->event;
                res = POLLERR;
        }
        spin_unlock(&vfsmount_lock);

        return res;
}

static struct file_operations proc_mounts_operations = {
        .open           = mounts_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = mounts_release,
        .poll           = mounts_poll,
};

extern struct seq_operations mountstats_op;
static int mountstats_open(struct inode *inode, struct file *file)
{
        int ret = seq_open(file, &mountstats_op);

        if (!ret) {
                struct seq_file *m = file->private_data;
                struct namespace *namespace = NULL;
                struct task_struct *task = get_proc_task(inode);

                if (task) {
                        task_lock(task);
                        namespace = task->namespace;
                        if (namespace)
                                get_namespace(namespace);
                        task_unlock(task);
                        put_task_struct(task);
                }

                if (namespace)
                        m->private = namespace;
                else {
                        seq_release(inode, file);
                        ret = -EINVAL;
                }
        }
        return ret;
}

static struct file_operations proc_mountstats_operations = {
        .open           = mountstats_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = mounts_release,
};

#define PROC_BLOCK_SIZE (3*1024)                /* 4K page size but our output routines use some slack for overruns */

static ssize_t proc_info_read(struct file * file, char __user * buf,
                          size_t count, loff_t *ppos)
{
        struct inode * inode = file->f_dentry->d_inode;
        unsigned long page;
        ssize_t length;
        struct task_struct *task = get_proc_task(inode);

        length = -ESRCH;
        if (!task)
                goto out_no_task;

        if (count > PROC_BLOCK_SIZE)
                count = PROC_BLOCK_SIZE;

        length = -ENOMEM;
        if (!(page = __get_free_page(GFP_KERNEL)))
                goto out;

        length = PROC_I(inode)->op.proc_read(task, (char*)page);

        if (length >= 0)
                length = simple_read_from_buffer(buf, count, ppos, (char *)page, length);
        free_page(page);
out:
        put_task_struct(task);
out_no_task:
        return length;
}

static struct file_operations proc_info_file_operations = {
        .read           = proc_info_read,
};

static int mem_open(struct inode* inode, struct file* file)
{
        file->private_data = (void*)((long)current->self_exec_id);
        return 0;
}

static ssize_t mem_read(struct file * file, char __user * buf,
                        size_t count, loff_t *ppos)
{
        struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
        char *page;
        unsigned long src = *ppos;
        int ret = -ESRCH;
        struct mm_struct *mm;

        if (!task)
                goto out_no_task;

        if (!MAY_PTRACE(task) || !ptrace_may_attach(task))
                goto out;

        ret = -ENOMEM;
        page = (char *)__get_free_page(GFP_USER);
        if (!page)
                goto out;

        ret = 0;
 
        mm = get_task_mm(task);
        if (!mm)
                goto out_free;

        ret = -EIO;
 
        if (file->private_data != (void*)((long)current->self_exec_id))
                goto out_put;

        ret = 0;
 
        while (count > 0) {
                int this_len, retval;

                this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
                retval = access_process_vm(task, src, page, this_len, 0);
                if (!retval || !MAY_PTRACE(task) || !ptrace_may_attach(task)) {
                        if (!ret)
                                ret = -EIO;
                        break;
                }

                if (copy_to_user(buf, page, retval)) {
                        ret = -EFAULT;
                        break;
                }
 
                ret += retval;
                src += retval;
                buf += retval;
                count -= retval;
        }
        *ppos = src;

out_put:
        mmput(mm);
out_free:
        free_page((unsigned long) page);
out:
        put_task_struct(task);
out_no_task:
        return ret;
}

#define mem_write NULL

#ifndef mem_write
/* This is a security hazard */
static ssize_t mem_write(struct file * file, const char * buf,
                         size_t count, loff_t *ppos)
{
        int copied = 0;
        char *page;
        struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
        unsigned long dst = *ppos;

        copied = -ESRCH;
        if (!task)
                goto out_no_task;

        if (!MAY_PTRACE(task) || !ptrace_may_attach(task))
                goto out;

        copied = -ENOMEM;
        page = (char *)__get_free_page(GFP_USER);
        if (!page)
                goto out;

        while (count > 0) {
                int this_len, retval;

                this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
                if (copy_from_user(page, buf, this_len)) {
                        copied = -EFAULT;
                        break;
                }
                retval = access_process_vm(task, dst, page, this_len, 1);
                if (!retval) {
                        if (!copied)
                                copied = -EIO;
                        break;
                }
                copied += retval;
                buf += retval;
                dst += retval;
                count -= retval;                        
        }
        *ppos = dst;
        free_page((unsigned long) page);
out:
        put_task_struct(task);
out_no_task:
        return copied;
}
#endif

static loff_t mem_lseek(struct file * file, loff_t offset, int orig)
{
        switch (orig) {
        case 0:
                file->f_pos = offset;
                break;
        case 1:
                file->f_pos += offset;
                break;
        default:
                return -EINVAL;
        }
        force_successful_syscall_return();
        return file->f_pos;
}

static struct file_operations proc_mem_operations = {
        .llseek         = mem_lseek,
        .read           = mem_read,
        .write          = mem_write,
        .open           = mem_open,
};

static ssize_t oom_adjust_read(struct file *file, char __user *buf,
                                size_t count, loff_t *ppos)
{
        struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
        char buffer[PROC_NUMBUF];
        size_t len;
        int oom_adjust;
        loff_t __ppos = *ppos;

        if (!task)
                return -ESRCH;
        oom_adjust = task->oomkilladj;
        put_task_struct(task);

        len = snprintf(buffer, sizeof(buffer), "%i\n", oom_adjust);
        if (__ppos >= len)
                return 0;
        if (count > len-__ppos)
                count = len-__ppos;
        if (copy_to_user(buf, buffer + __ppos, count))
                return -EFAULT;
        *ppos = __ppos + count;
        return count;
}

static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        struct task_struct *task;
        char buffer[PROC_NUMBUF], *end;
        int oom_adjust;

        if (!capable(CAP_SYS_RESOURCE))
                return -EPERM;
        memset(buffer, 0, sizeof(buffer));
        if (count > sizeof(buffer) - 1)
                count = sizeof(buffer) - 1;
        if (copy_from_user(buffer, buf, count))
                return -EFAULT;
        oom_adjust = simple_strtol(buffer, &end, 0);
        if ((oom_adjust < -16 || oom_adjust > 15) && oom_adjust != OOM_DISABLE)
                return -EINVAL;
        if (*end == '\n')
                end++;
        task = get_proc_task(file->f_dentry->d_inode);
        if (!task)
                return -ESRCH;
        task->oomkilladj = oom_adjust;
        put_task_struct(task);
        if (end - buffer == 0)
                return -EIO;
        return end - buffer;
}

static struct file_operations proc_oom_adjust_operations = {
        .read           = oom_adjust_read,
        .write          = oom_adjust_write,
};

#ifdef CONFIG_AUDITSYSCALL
#define TMPBUFLEN 21
static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
                                  size_t count, loff_t *ppos)
{
        struct inode * inode = file->f_dentry->d_inode;
        struct task_struct *task = get_proc_task(inode);
        ssize_t length;
        char tmpbuf[TMPBUFLEN];

        if (!task)
                return -ESRCH;
        length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
                                audit_get_loginuid(task->audit_context));
        put_task_struct(task);
        return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}

static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
                                   size_t count, loff_t *ppos)
{
        struct inode * inode = file->f_dentry->d_inode;
        char *page, *tmp;
        ssize_t length;
        uid_t loginuid;

        if (!capable(CAP_AUDIT_CONTROL))
                return -EPERM;

        if (current != pid_task(proc_pid(inode), PIDTYPE_PID))
                return -EPERM;

        if (count >= PAGE_SIZE)
                count = PAGE_SIZE - 1;

        if (*ppos != 0) {
                /* No partial writes. */
                return -EINVAL;
        }
        page = (char*)__get_free_page(GFP_USER);
        if (!page)
                return -ENOMEM;
        length = -EFAULT;
        if (copy_from_user(page, buf, count))
                goto out_free_page;

        page[count] = '\0';
        loginuid = simple_strtoul(page, &tmp, 10);
        if (tmp == page) {
                length = -EINVAL;
                goto out_free_page;

        }
        length = audit_set_loginuid(current, loginuid);
        if (likely(length == 0))
                length = count;

out_free_page:
        free_page((unsigned long) page);
        return length;
}

static struct file_operations proc_loginuid_operations = {
        .read           = proc_loginuid_read,
        .write          = proc_loginuid_write,
};
#endif

#ifdef CONFIG_SECCOMP
static ssize_t seccomp_read(struct file *file, char __user *buf,
                            size_t count, loff_t *ppos)
{
        struct task_struct *tsk = get_proc_task(file->f_dentry->d_inode);
        char __buf[20];
        loff_t __ppos = *ppos;
        size_t len;

        if (!tsk)
                return -ESRCH;
        /* no need to print the trailing zero, so use only len */
        len = sprintf(__buf, "%u\n", tsk->seccomp.mode);
        put_task_struct(tsk);
        if (__ppos >= len)
                return 0;
        if (count > len - __ppos)
                count = len - __ppos;
        if (copy_to_user(buf, __buf + __ppos, count))
                return -EFAULT;
        *ppos = __ppos + count;
        return count;
}

static ssize_t seccomp_write(struct file *file, const char __user *buf,
                             size_t count, loff_t *ppos)
{
        struct task_struct *tsk = get_proc_task(file->f_dentry->d_inode);
        char __buf[20], *end;
        unsigned int seccomp_mode;
        ssize_t result;

        result = -ESRCH;
        if (!tsk)
                goto out_no_task;

        /* can set it only once to be even more secure */
        result = -EPERM;
        if (unlikely(tsk->seccomp.mode))
                goto out;

        result = -EFAULT;
        memset(__buf, 0, sizeof(__buf));
        count = min(count, sizeof(__buf) - 1);
        if (copy_from_user(__buf, buf, count))
                goto out;

        seccomp_mode = simple_strtoul(__buf, &end, 0);
        if (*end == '\n')
                end++;
        result = -EINVAL;
        if (seccomp_mode && seccomp_mode <= NR_SECCOMP_MODES) {
                tsk->seccomp.mode = seccomp_mode;
                set_tsk_thread_flag(tsk, TIF_SECCOMP);
        } else
                goto out;
        result = -EIO;
        if (unlikely(!(end - __buf)))
                goto out;
        result = end - __buf;
out:
        put_task_struct(tsk);
out_no_task:
        return result;
}

static struct file_operations proc_seccomp_operations = {
        .read           = seccomp_read,
        .write          = seccomp_write,
};
#endif /* CONFIG_SECCOMP */

static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
{
        struct inode *inode = dentry->d_inode;
        int error = -EACCES;

        /* We don't need a base pointer in the /proc filesystem */
        path_release(nd);

        /* Are we allowed to snoop on the tasks file descriptors? */
        if (!proc_fd_access_allowed(inode))
                goto out;

        error = PROC_I(inode)->op.proc_get_link(inode, &nd->dentry, &nd->mnt);
        nd->last_type = LAST_BIND;
out:
        return ERR_PTR(error);
}

static int do_proc_readlink(struct dentry *dentry, struct vfsmount *mnt,
                            char __user *buffer, int buflen)
{
        struct inode * inode;
        char *tmp = (char*)__get_free_page(GFP_KERNEL), *path;
        int len;

        if (!tmp)
                return -ENOMEM;
                
        inode = dentry->d_inode;
        path = d_path(dentry, mnt, tmp, PAGE_SIZE);
        len = PTR_ERR(path);
        if (IS_ERR(path))
                goto out;
        len = tmp + PAGE_SIZE - 1 - path;

        if (len > buflen)
                len = buflen;
        if (copy_to_user(buffer, path, len))
                len = -EFAULT;
 out:
        free_page((unsigned long)tmp);
        return len;
}

static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int buflen)
{
        int error = -EACCES;
        struct inode *inode = dentry->d_inode;
        struct dentry *de;
        struct vfsmount *mnt = NULL;

        /* Are we allowed to snoop on the tasks file descriptors? */
        if (!proc_fd_access_allowed(inode))
                goto out;

        error = PROC_I(inode)->op.proc_get_link(inode, &de, &mnt);
        if (error)
                goto out;

        error = do_proc_readlink(de, mnt, buffer, buflen);
        dput(de);
        mntput(mnt);
out:
        return error;
}

static struct inode_operations proc_pid_link_inode_operations = {
        .readlink       = proc_pid_readlink,
        .follow_link    = proc_pid_follow_link,
        .setattr        = proc_setattr,
};

static int proc_readfd(struct file * filp, void * dirent, filldir_t filldir)
{
        struct dentry *dentry = filp->f_dentry;
        struct inode *inode = dentry->d_inode;
        struct task_struct *p = get_proc_task(inode);
        unsigned int fd, tid, ino;
        int retval;
        char buf[PROC_NUMBUF];
        struct files_struct * files;
        struct fdtable *fdt;

        retval = -ENOENT;
        if (!p)
                goto out_no_task;
        retval = 0;
        tid = p->pid;

        fd = filp->f_pos;
        switch (fd) {
                case 0:
                        if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0)
                                goto out;
                        filp->f_pos++;
                case 1:
                        ino = parent_ino(dentry);
                        if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
                                goto out;
                        filp->f_pos++;
                default:
                        files = get_files_struct(p);
                        if (!files)
                                goto out;
                        rcu_read_lock();
                        fdt = files_fdtable(files);
                        for (fd = filp->f_pos-2;
                             fd < fdt->max_fds;
                             fd++, filp->f_pos++) {
                                unsigned int i,j;

                                if (!fcheck_files(files, fd))
                                        continue;
                                rcu_read_unlock();

                                j = PROC_NUMBUF;
                                i = fd;
                                do {
                                        j--;
                                        buf[j] = '0' + (i % 10);
                                        i /= 10;
                                } while (i);

                                ino = fake_ino(tid, PROC_TID_FD_DIR + fd);
                                if (filldir(dirent, buf+j, PROC_NUMBUF-j, fd+2, ino, DT_LNK) < 0) {
                                        rcu_read_lock();
                                        break;
                                }
                                rcu_read_lock();
                        }
                        rcu_read_unlock();
                        put_files_struct(files);
        }
out:
        put_task_struct(p);
out_no_task:
        return retval;
}

static int proc_pident_readdir(struct file *filp,
                void *dirent, filldir_t filldir,
                struct pid_entry *ents, unsigned int nents)
{
        int i;
        int pid;
        struct dentry *dentry = filp->f_dentry;
        struct inode *inode = dentry->d_inode;
        struct task_struct *task = get_proc_task(inode);
        struct pid_entry *p;
        ino_t ino;
        int ret;

        ret = -ENOENT;
        if (!task)
                goto out;

        ret = 0;
        pid = task->pid;
        put_task_struct(task);
        i = filp->f_pos;
        switch (i) {
        case 0:
                ino = inode->i_ino;
                if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
                        goto out;
                i++;
                filp->f_pos++;
                /* fall through */
        case 1:
                ino = parent_ino(dentry);
                if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
                        goto out;
                i++;
                filp->f_pos++;
                /* fall through */
        default:
                i -= 2;
                if (i >= nents) {
                        ret = 1;
                        goto out;
                }
                p = ents + i;
                while (p->name) {
                        if (filldir(dirent, p->name, p->len, filp->f_pos,
                                    fake_ino(pid, p->type), p->mode >> 12) < 0)
                                goto out;
                        filp->f_pos++;
                        p++;
                }
        }

        ret = 1;
out:
        return ret;
}

static int proc_tgid_base_readdir(struct file * filp,
                             void * dirent, filldir_t filldir)
{
        return proc_pident_readdir(filp,dirent,filldir,
                                   tgid_base_stuff,ARRAY_SIZE(tgid_base_stuff));
}

static int proc_tid_base_readdir(struct file * filp,
                             void * dirent, filldir_t filldir)
{
        return proc_pident_readdir(filp,dirent,filldir,
                                   tid_base_stuff,ARRAY_SIZE(tid_base_stuff));
}

/* building an inode */

static int task_dumpable(struct task_struct *task)
{
        int dumpable = 0;
        struct mm_struct *mm;

        task_lock(task);
        mm = task->mm;
        if (mm)
                dumpable = mm->dumpable;
        task_unlock(task);
        if(dumpable == 1)
                return 1;
        return 0;
}


static struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *task, int ino)
{
        struct inode * inode;
        struct proc_inode *ei;

        /* We need a new inode */
        
        inode = new_inode(sb);
        if (!inode)
                goto out;

        /* Common stuff */
        ei = PROC_I(inode);
        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
        inode->i_ino = fake_ino(task->pid, ino);
        inode->i_op = &proc_def_inode_operations;

        /*
         * grab the reference to task.
         */
        ei->pid = get_pid(task->pids[PIDTYPE_PID].pid);
        if (!ei->pid)
                goto out_unlock;

        inode->i_uid = 0;
        inode->i_gid = 0;
        if (task_dumpable(task)) {
                inode->i_uid = task->euid;
                inode->i_gid = task->egid;
        }
        security_task_to_inode(task, inode);

out:
        return inode;

out_unlock:
        iput(inode);
        return NULL;
}

/* dentry stuff */

/*
 *      Exceptional case: normally we are not allowed to unhash a busy
 * directory. In this case, however, we can do it - no aliasing problems
 * due to the way we treat inodes.
 *
 * Rewrite the inode's ownerships here because the owning task may have
 * performed a setuid(), etc.
 *
 * Before the /proc/pid/status file was created the only way to read
 * the effective uid of a /process was to stat /proc/pid.  Reading
 * /proc/pid/status is slow enough that procps and other packages
 * kept stating /proc/pid.  To keep the rules in /proc simple I have
 * made this apply to all per process world readable and executable
 * directories.
 */
static int pid_revalidate(struct dentry *dentry, struct nameidata *nd)
{
        struct inode *inode = dentry->d_inode;
        struct task_struct *task = get_proc_task(inode);
        if (task) {
                if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
                    task_dumpable(task)) {
                        inode->i_uid = task->euid;
                        inode->i_gid = task->egid;
                } else {
                        inode->i_uid = 0;
                        inode->i_gid = 0;
                }
                inode->i_mode &= ~(S_ISUID | S_ISGID);
                security_task_to_inode(task, inode);
                put_task_struct(task);
                return 1;
        }
        d_drop(dentry);
        return 0;
}

static int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
        struct inode *inode = dentry->d_inode;
        struct task_struct *task;
        generic_fillattr(inode, stat);

        rcu_read_lock();
        stat->uid = 0;
        stat->gid = 0;
        task = pid_task(proc_pid(inode), PIDTYPE_PID);
        if (task) {
                if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
                    task_dumpable(task)) {
                        stat->uid = task->euid;
                        stat->gid = task->egid;
                }
        }
        rcu_read_unlock();
        return 0;
}

static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
{
        struct inode *inode = dentry->d_inode;
        struct task_struct *task = get_proc_task(inode);
        int fd = proc_fd(inode);
        struct files_struct *files;

        if (task) {
                files = get_files_struct(task);
                if (files) {
                        rcu_read_lock();
                        if (fcheck_files(files, fd)) {
                                rcu_read_unlock();
                                put_files_struct(files);
                                if (task_dumpable(task)) {
                                        inode->i_uid = task->euid;
                                        inode->i_gid = task->egid;
                                } else {
                                        inode->i_uid = 0;
                                        inode->i_gid = 0;
                                }
                                inode->i_mode &= ~(S_ISUID | S_ISGID);
                                security_task_to_inode(task, inode);
                                put_task_struct(task);
                                return 1;
                        }
                        rcu_read_unlock();
                        put_files_struct(files);
                }
                put_task_struct(task);
        }
        d_drop(dentry);
        return 0;
}

static int pid_delete_dentry(struct dentry * dentry)
{
        /* Is the task we represent dead?
         * If so, then don't put the dentry on the lru list,
         * kill it immediately.
         */
        return !proc_pid(dentry->d_inode)->tasks[PIDTYPE_PID].first;
}

static struct dentry_operations tid_fd_dentry_operations =
{
        .d_revalidate   = tid_fd_revalidate,
        .d_delete       = pid_delete_dentry,
};

static struct dentry_operations pid_dentry_operations =
{
        .d_revalidate   = pid_revalidate,
        .d_delete       = pid_delete_dentry,
};

/* Lookups */

static unsigned name_to_int(struct dentry *dentry)
{
        const char *name = dentry->d_name.name;
        int len = dentry->d_name.len;
        unsigned n = 0;

        if (len > 1 && *name == '0')
                goto out;
        while (len-- > 0) {
                unsigned c = *name++ - '0';
                if (c > 9)
                        goto out;
                if (n >= (~0U-9)/10)
                        goto out;
                n *= 10;
                n += c;
        }
        return n;
out:
        return ~0U;
}

/* SMP-safe */
static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
{
        struct task_struct *task = get_proc_task(dir);
        unsigned fd = name_to_int(dentry);
        struct dentry *result = ERR_PTR(-ENOENT);
        struct file * file;
        struct files_struct * files;
        struct inode *inode;
        struct proc_inode *ei;

        if (!task)
                goto out_no_task;
        if (fd == ~0U)
                goto out;

        inode = proc_pid_make_inode(dir->i_sb, task, PROC_TID_FD_DIR+fd);
        if (!inode)
                goto out;
        ei = PROC_I(inode);
        ei->fd = fd;
        files = get_files_struct(task);
        if (!files)
                goto out_unlock;
        inode->i_mode = S_IFLNK;

        /*
         * We are not taking a ref to the file structure, so we must
         * hold ->file_lock.
         */
        spin_lock(&files->file_lock);
        file = fcheck_files(files, fd);
        if (!file)
                goto out_unlock2;
        if (file->f_mode & 1)
                inode->i_mode |= S_IRUSR | S_IXUSR;
        if (file->f_mode & 2)
                inode->i_mode |= S_IWUSR | S_IXUSR;
        spin_unlock(&files->file_lock);
        put_files_struct(files);
        inode->i_op = &proc_pid_link_inode_operations;
        inode->i_size = 64;
        ei->op.proc_get_link = proc_fd_link;
        dentry->d_op = &tid_fd_dentry_operations;
        d_add(dentry, inode);
        /* Close the race of the process dying before we return the dentry */
        if (tid_fd_revalidate(dentry, NULL))
                result = NULL;
out:
        put_task_struct(task);
out_no_task:
        return result;

out_unlock2:
        spin_unlock(&files->file_lock);
        put_files_struct(files);
out_unlock:
        iput(inode);
        goto out;
}

static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir);
static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd);
static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat);

static struct file_operations proc_fd_operations = {
        .read           = generic_read_dir,
        .readdir        = proc_readfd,
};

static struct file_operations proc_task_operations = {
        .read           = generic_read_dir,
        .readdir        = proc_task_readdir,
};

/*
 * proc directories can do almost nothing..
 */
static struct inode_operations proc_fd_inode_operations = {
        .lookup         = proc_lookupfd,
        .setattr        = proc_setattr,
};

static struct inode_operations proc_task_inode_operations = {
        .lookup         = proc_task_lookup,
        .getattr        = proc_task_getattr,
        .setattr        = proc_setattr,
};

#ifdef CONFIG_SECURITY
static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
                                  size_t count, loff_t *ppos)
{
        struct inode * inode = file->f_dentry->d_inode;
        unsigned long page;
        ssize_t length;
        struct task_struct *task = get_proc_task(inode);

        length = -ESRCH;
        if (!task)
                goto out_no_task;

        if (count > PAGE_SIZE)
                count = PAGE_SIZE;
        length = -ENOMEM;
        if (!(page = __get_free_page(GFP_KERNEL)))
                goto out;

        length = security_getprocattr(task, 
                                      (char*)file->f_dentry->d_name.name, 
                                      (void*)page, count);
        if (length >= 0)
                length = simple_read_from_buffer(buf, count, ppos, (char *)page, length);
        free_page(page);
out:
        put_task_struct(task);
out_no_task:
        return length;
}

static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
                                   size_t count, loff_t *ppos)
{ 
        struct inode * inode = file->f_dentry->d_inode;
        char *page; 
        ssize_t length; 
        struct task_struct *task = get_proc_task(inode);

        length = -ESRCH;
        if (!task)
                goto out_no_task;
        if (count > PAGE_SIZE) 
                count = PAGE_SIZE; 

        /* No partial writes. */
        length = -EINVAL;
        if (*ppos != 0)
                goto out;

        length = -ENOMEM;
        page = (char*)__get_free_page(GFP_USER); 
        if (!page) 
                goto out;

        length = -EFAULT; 
        if (copy_from_user(page, buf, count)) 
                goto out_free;

        length = security_setprocattr(task, 
                                      (char*)file->f_dentry->d_name.name, 
                                      (void*)page, count);
out_free:
        free_page((unsigned long) page);
out:
        put_task_struct(task);
out_no_task:
        return length;
} 

static struct file_operations proc_pid_attr_operations = {
        .read           = proc_pid_attr_read,
        .write          = proc_pid_attr_write,
};

static struct file_operations proc_tid_attr_operations;
static struct inode_operations proc_tid_attr_inode_operations;
static struct file_operations proc_tgid_attr_operations;
static struct inode_operations proc_tgid_attr_inode_operations;
#endif

/* SMP-safe */
static struct dentry *proc_pident_lookup(struct inode *dir, 
                                         struct dentry *dentry,
                                         struct pid_entry *ents)
{
        struct inode *inode;
        struct dentry *error;
        struct task_struct *task = get_proc_task(dir);
        struct pid_entry *p;
        struct proc_inode *ei;

        error = ERR_PTR(-ENOENT);
        inode = NULL;

        if (!task)
                goto out_no_task;

        for (p = ents; p->name; p++) {
                if (p->len != dentry->d_name.len)
                        continue;
                if (!memcmp(dentry->d_name.name, p->name, p->len))
                        break;
        }
        if (!p->name)
                goto out;

        error = ERR_PTR(-EINVAL);
        inode = proc_pid_make_inode(dir->i_sb, task, p->type);
        if (!inode)
                goto out;

        ei = PROC_I(inode);
        inode->i_mode = p->mode;
        /*
         * Yes, it does not scale. And it should not. Don't add
         * new entries into /proc/<tgid>/ without very good reasons.
         */
        switch(p->type) {
                case PROC_TGID_TASK:
                        inode->i_nlink = 2;
                        inode->i_op = &proc_task_inode_operations;
                        inode->i_fop = &proc_task_operations;
                        break;
                case PROC_TID_FD:
                case PROC_TGID_FD:
                        inode->i_nlink = 2;
                        inode->i_op = &proc_fd_inode_operations;
                        inode->i_fop = &proc_fd_operations;
                        break;
                case PROC_TID_EXE:
                case PROC_TGID_EXE:
                        inode->i_op = &proc_pid_link_inode_operations;
                        ei->op.proc_get_link = proc_exe_link;
                        break;
                case PROC_TID_CWD:
                case PROC_TGID_CWD:
                        inode->i_op = &proc_pid_link_inode_operations;
                        ei->op.proc_get_link = proc_cwd_link;
                        break;
                case PROC_TID_ROOT:
                case PROC_TGID_ROOT:
                        inode->i_op = &proc_pid_link_inode_operations;
                        ei->op.proc_get_link = proc_root_link;
                        break;
                case PROC_TID_ENVIRON:
                case PROC_TGID_ENVIRON:
                        inode->i_fop = &proc_info_file_operations;
                        ei->op.proc_read = proc_pid_environ;
                        break;
                case PROC_TID_AUXV:
                case PROC_TGID_AUXV:
                        inode->i_fop = &proc_info_file_operations;
                        ei->op.proc_read = proc_pid_auxv;
                        break;
                case PROC_TID_STATUS:
                case PROC_TGID_STATUS:
                        inode->i_fop = &proc_info_file_operations;
                        ei->op.proc_read = proc_pid_status;
                        break;
                case PROC_TID_STAT:
                        inode->i_fop = &proc_info_file_operations;
                        ei->op.proc_read = proc_tid_stat;
                        break;
                case PROC_TGID_STAT:
                        inode->i_fop = &proc_info_file_operations;
                        ei->op.proc_read = proc_tgid_stat;
                        break;
                case PROC_TID_CMDLINE:
                case PROC_TGID_CMDLINE:
                        inode->i_fop = &proc_info_file_operations;
                        ei->op.proc_read = proc_pid_cmdline;
                        break;
                case PROC_TID_STATM:
                case PROC_TGID_STATM:
                        inode->i_fop = &proc_info_file_operations;
                        ei->op.proc_read = proc_pid_statm;
                        break;
                case PROC_TID_MAPS:
                case PROC_TGID_MAPS:
                        inode->i_fop = &proc_maps_operations;
                        break;
#ifdef CONFIG_NUMA
                case PROC_TID_NUMA_MAPS:
                case PROC_TGID_NUMA_MAPS:
                        inode->i_fop = &proc_numa_maps_operations;
                        break;
#endif
                case PROC_TID_MEM:
                case PROC_TGID_MEM:
                        inode->i_fop = &proc_mem_operations;
                        break;
#ifdef CONFIG_SECCOMP
                case PROC_TID_SECCOMP:
                case PROC_TGID_SECCOMP:
                        inode->i_fop = &proc_seccomp_operations;
                        break;
#endif /* CONFIG_SECCOMP */
                case PROC_TID_MOUNTS:
                case PROC_TGID_MOUNTS:
                        inode->i_fop = &proc_mounts_operations;
                        break;
#ifdef CONFIG_MMU
                case PROC_TID_SMAPS:
                case PROC_TGID_SMAPS:
                        inode->i_fop = &proc_smaps_operations;
                        break;
#endif
                case PROC_TID_MOUNTSTATS:
                case PROC_TGID_MOUNTSTATS:
                        inode->i_fop = &proc_mountstats_operations;
                        break;
#ifdef CONFIG_SECURITY
                case PROC_TID_ATTR:
                        inode->i_nlink = 2;
                        inode->i_op = &proc_tid_attr_inode_operations;
                        inode->i_fop = &proc_tid_attr_operations;
                        break;
                case PROC_TGID_ATTR:
                        inode->i_nlink = 2;
                        inode->i_op = &proc_tgid_attr_inode_operations;
                        inode->i_fop = &proc_tgid_attr_operations;
                        break;
                case PROC_TID_ATTR_CURRENT:
                case PROC_TGID_ATTR_CURRENT:
                case PROC_TID_ATTR_PREV:
                case PROC_TGID_ATTR_PREV:
                case PROC_TID_ATTR_EXEC:
                case PROC_TGID_ATTR_EXEC:
                case PROC_TID_ATTR_FSCREATE:
                case PROC_TGID_ATTR_FSCREATE:
                case PROC_TID_ATTR_KEYCREATE:
                case PROC_TGID_ATTR_KEYCREATE:
                case PROC_TID_ATTR_SOCKCREATE:
                case PROC_TGID_ATTR_SOCKCREATE:
                        inode->i_fop = &proc_pid_attr_operations;
                        break;
#endif
#ifdef CONFIG_KALLSYMS
                case PROC_TID_WCHAN:
                case PROC_TGID_WCHAN:
                        inode->i_fop = &proc_info_file_operations;
                        ei->op.proc_read = proc_pid_wchan;
                        break;
#endif
#ifdef CONFIG_SCHEDSTATS
                case PROC_TID_SCHEDSTAT:
                case PROC_TGID_SCHEDSTAT:
                        inode->i_fop = &proc_info_file_operations;
                        ei->op.proc_read = proc_pid_schedstat;
                        break;
#endif
#ifdef CONFIG_CPUSETS
                case PROC_TID_CPUSET:
                case PROC_TGID_CPUSET:
                        inode->i_fop = &proc_cpuset_operations;
                        break;
#endif
                case PROC_TID_OOM_SCORE:
                case PROC_TGID_OOM_SCORE:
                        inode->i_fop = &proc_info_file_operations;
                        ei->op.proc_read = proc_oom_score;
                        break;
                case PROC_TID_OOM_ADJUST:
                case PROC_TGID_OOM_ADJUST:
                        inode->i_fop = &proc_oom_adjust_operations;
                        break;
#ifdef CONFIG_AUDITSYSCALL
                case PROC_TID_LOGINUID:
                case PROC_TGID_LOGINUID:
                        inode->i_fop = &proc_loginuid_operations;
                        break;
#endif
                default:
                        printk("procfs: impossible type (%d)",p->type);
                        iput(inode);
                        error = ERR_PTR(-EINVAL);
                        goto out;
        }
        dentry->d_op = &pid_dentry_operations;
        d_add(dentry, inode);
        /* Close the race of the process dying before we return the dentry */
        if (pid_revalidate(dentry, NULL))
                error = NULL;
out:
        put_task_struct(task);
out_no_task:
        return error;
}

static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
        return proc_pident_lookup(dir, dentry, tgid_base_stuff);
}

static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
        return proc_pident_lookup(dir, dentry, tid_base_stuff);
}

static struct file_operations proc_tgid_base_operations = {
        .read           = generic_read_dir,
        .readdir        = proc_tgid_base_readdir,
};

static struct file_operations proc_tid_base_operations = {
        .read           = generic_read_dir,
        .readdir        = proc_tid_base_readdir,
};

static struct inode_operations proc_tgid_base_inode_operations = {
        .lookup         = proc_tgid_base_lookup,
        .getattr        = pid_getattr,
        .setattr        = proc_setattr,
};

static struct inode_operations proc_tid_base_inode_operations = {
        .lookup         = proc_tid_base_lookup,
        .getattr        = pid_getattr,
        .setattr        = proc_setattr,
};

#ifdef CONFIG_SECURITY
static int proc_tgid_attr_readdir(struct file * filp,
                             void * dirent, filldir_t filldir)
{
        return proc_pident_readdir(filp,dirent,filldir,
                                   tgid_attr_stuff,ARRAY_SIZE(tgid_attr_stuff));
}

static int proc_tid_attr_readdir(struct file * filp,
                             void * dirent, filldir_t filldir)
{
        return proc_pident_readdir(filp,dirent,filldir,
                                   tid_attr_stuff,ARRAY_SIZE(tid_attr_stuff));
}

static struct file_operations proc_tgid_attr_operations = {
        .read           = generic_read_dir,
        .readdir        = proc_tgid_attr_readdir,
};

static struct file_operations proc_tid_attr_operations = {
        .read           = generic_read_dir,
        .readdir        = proc_tid_attr_readdir,
};

static struct dentry *proc_tgid_attr_lookup(struct inode *dir,
                                struct dentry *dentry, struct nameidata *nd)
{
        return proc_pident_lookup(dir, dentry, tgid_attr_stuff);
}

static struct dentry *proc_tid_attr_lookup(struct inode *dir,
                                struct dentry *dentry, struct nameidata *nd)
{
        return proc_pident_lookup(dir, dentry, tid_attr_stuff);
}

static struct inode_operations proc_tgid_attr_inode_operations = {
        .lookup         = proc_tgid_attr_lookup,
        .getattr        = pid_getattr,
        .setattr        = proc_setattr,
};

static struct inode_operations proc_tid_attr_inode_operations = {
        .lookup         = proc_tid_attr_lookup,
        .getattr        = pid_getattr,
        .setattr        = proc_setattr,
};
#endif

/*
 * /proc/self:
 */
static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
                              int buflen)
{
        char tmp[PROC_NUMBUF];
        sprintf(tmp, "%d", current->tgid);
        return vfs_readlink(dentry,buffer,buflen,tmp);
}

static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
{
        char tmp[PROC_NUMBUF];
        sprintf(tmp, "%d", current->tgid);
        return ERR_PTR(vfs_follow_link(nd,tmp));
}       

static struct inode_operations proc_self_inode_operations = {
        .readlink       = proc_self_readlink,
        .follow_link    = proc_self_follow_link,
};

/**
 * proc_flush_task -  Remove dcache entries for @task from the /proc dcache.
 *
 * @task: task that should be flushed.
 *
 * Looks in the dcache for
 * /proc/@pid
 * /proc/@tgid/task/@pid
 * if either directory is present flushes it and all of it'ts children
 * from the dcache.
 *
 * It is safe and reasonable to cache /proc entries for a task until
 * that task exits.  After that they just clog up the dcache with
 * useless entries, possibly causing useful dcache entries to be
 * flushed instead.  This routine is proved to flush those useless
 * dcache entries at process exit time.
 *
 * NOTE: This routine is just an optimization so it does not guarantee
 *       that no dcache entries will exist at process exit time it
 *       just makes it very unlikely that any will persist.
 */
void proc_flush_task(struct task_struct *task)
{
        struct dentry *dentry, *leader, *dir;
        char buf[PROC_NUMBUF];
        struct qstr name;

        name.name = buf;
        name.len = snprintf(buf, sizeof(buf), "%d", task->pid);
        dentry = d_hash_and_lookup(proc_mnt->mnt_root, &name);
        if (dentry) {
                shrink_dcache_parent(dentry);
                d_drop(dentry);
                dput(dentry);
        }

        if (thread_group_leader(task))
                goto out;

        name.name = buf;
        name.len = snprintf(buf, sizeof(buf), "%d", task->tgid);
        leader = d_hash_and_lookup(proc_mnt->mnt_root, &name);
        if (!leader)
                goto out;

        name.name = "task";
        name.len = strlen(name.name);
        dir = d_hash_and_lookup(leader, &name);
        if (!dir)
                goto out_put_leader;

        name.name = buf;
        name.len = snprintf(buf, sizeof(buf), "%d", task->pid);
        dentry = d_hash_and_lookup(dir, &name);
        if (dentry) {
                shrink_dcache_parent(dentry);
                d_drop(dentry);
                dput(dentry);
        }

        dput(dir);
out_put_leader:
        dput(leader);
out:
        return;
}

/* SMP-safe */
struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
{
        struct dentry *result = ERR_PTR(-ENOENT);
        struct task_struct *task;
        struct inode *inode;
        struct proc_inode *ei;
        unsigned tgid;

        if (dentry->d_name.len == 4 && !memcmp(dentry->d_name.name,"self",4)) {
                inode = new_inode(dir->i_sb);
                if (!inode)
                        return ERR_PTR(-ENOMEM);
                ei = PROC_I(inode);
                inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
                inode->i_ino = fake_ino(0, PROC_TGID_INO);
                ei->pde = NULL;
                inode->i_mode = S_IFLNK|S_IRWXUGO;
                inode->i_uid = inode->i_gid = 0;
                inode->i_size = 64;
                inode->i_op = &proc_self_inode_operations;
                d_add(dentry, inode);
                return NULL;
        }
        tgid = name_to_int(dentry);
        if (tgid == ~0U)
                goto out;

        rcu_read_lock();
        task = find_task_by_pid(tgid);
        if (task)
                get_task_struct(task);
        rcu_read_unlock();
        if (!task)
                goto out;

        inode = proc_pid_make_inode(dir->i_sb, task, PROC_TGID_INO);
        if (!inode)
                goto out_put_task;

        inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
        inode->i_op = &proc_tgid_base_inode_operations;
        inode->i_fop = &proc_tgid_base_operations;
        inode->i_flags|=S_IMMUTABLE;
#ifdef CONFIG_SECURITY
        inode->i_nlink = 5;
#else
        inode->i_nlink = 4;
#endif

        dentry->d_op = &pid_dentry_operations;

        d_add(dentry, inode);
        /* Close the race of the process dying before we return the dentry */
        if (pid_revalidate(dentry, NULL))
                result = NULL;

out_put_task:
        put_task_struct(task);
out:
        return result;
}

/* SMP-safe */
static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
{
        struct dentry *result = ERR_PTR(-ENOENT);
        struct task_struct *task;
        struct task_struct *leader = get_proc_task(dir);
        struct inode *inode;
        unsigned tid;

        if (!leader)
                goto out_no_task;

        tid = name_to_int(dentry);
        if (tid == ~0U)
                goto out;

        rcu_read_lock();
        task = find_task_by_pid(tid);
        if (task)
                get_task_struct(task);
        rcu_read_unlock();
        if (!task)
                goto out;
        if (leader->tgid != task->tgid)
                goto out_drop_task;

        inode = proc_pid_make_inode(dir->i_sb, task, PROC_TID_INO);


        if (!inode)
                goto out_drop_task;
        inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
        inode->i_op = &proc_tid_base_inode_operations;
        inode->i_fop = &proc_tid_base_operations;
        inode->i_flags|=S_IMMUTABLE;
#ifdef CONFIG_SECURITY
        inode->i_nlink = 4;
#else
        inode->i_nlink = 3;
#endif

        dentry->d_op = &pid_dentry_operations;

        d_add(dentry, inode);
        /* Close the race of the process dying before we return the dentry */
        if (pid_revalidate(dentry, NULL))
                result = NULL;

out_drop_task:
        put_task_struct(task);
out:
        put_task_struct(leader);
out_no_task:
        return result;
}

/*
 * Find the first tgid to return to user space.
 *
 * Usually this is just whatever follows &init_task, but if the users
 * buffer was too small to hold the full list or there was a seek into
 * the middle of the directory we have more work to do.
 *
 * In the case of a short read we start with find_task_by_pid.
 *
 * In the case of a seek we start with &init_task and walk nr
 * threads past it.
 */
static struct task_struct *first_tgid(int tgid, unsigned int nr)
{
        struct task_struct *pos;
        rcu_read_lock();
        if (tgid && nr) {
                pos = find_task_by_pid(tgid);
                if (pos && thread_group_leader(pos))
                        goto found;
        }
        /* If nr exceeds the number of processes get out quickly */
        pos = NULL;
        if (nr && nr >= nr_processes())
                goto done;

        /* If we haven't found our starting place yet start with
         * the init_task and walk nr tasks forward.
         */
        for (pos = next_task(&init_task); nr > 0; --nr) {
                pos = next_task(pos);
                if (pos == &init_task) {
                        pos = NULL;
                        goto done;
                }
        }
found:
        get_task_struct(pos);
done:
        rcu_read_unlock();
        return pos;
}

/*
 * Find the next task in the task list.
 * Return NULL if we loop or there is any error.
 *
 * The reference to the input task_struct is released.
 */
static struct task_struct *next_tgid(struct task_struct *start)
{
        struct task_struct *pos;
        rcu_read_lock();
        pos = start;
        if (pid_alive(start))
                pos = next_task(start);
        if (pid_alive(pos) && (pos != &init_task)) {
                get_task_struct(pos);
                goto done;
        }
        pos = NULL;
done:
        rcu_read_unlock();
        put_task_struct(start);
        return pos;
}

/* for the /proc/ directory itself, after non-process stuff has been done */
int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
        char buf[PROC_NUMBUF];
        unsigned int nr = filp->f_pos - FIRST_PROCESS_ENTRY;
        struct task_struct *task;
        int tgid;

        if (!nr) {
                ino_t ino = fake_ino(0,PROC_TGID_INO);
                if (filldir(dirent, "self", 4, filp->f_pos, ino, DT_LNK) < 0)
                        return 0;
                filp->f_pos++;
                nr++;
        }
        nr -= 1;

        /* f_version caches the tgid value that the last readdir call couldn't
         * return. lseek aka telldir automagically resets f_version to 0.
         */
        tgid = filp->f_version;
        filp->f_version = 0;
        for (task = first_tgid(tgid, nr);
             task;
             task = next_tgid(task), filp->f_pos++) {
                int len;
                ino_t ino;
                tgid = task->pid;
                len = snprintf(buf, sizeof(buf), "%d", tgid);
                ino = fake_ino(tgid, PROC_TGID_INO);
                if (filldir(dirent, buf, len, filp->f_pos, ino, DT_DIR) < 0) {
                        /* returning this tgid failed, save it as the first
                         * pid for the next readir call */
                        filp->f_version = tgid;
                        put_task_struct(task);
                        break;
                }
        }
        return 0;
}

/*
 * Find the first tid of a thread group to return to user space.
 *
 * Usually this is just the thread group leader, but if the users
 * buffer was too small or there was a seek into the middle of the
 * directory we have more work todo.
 *
 * In the case of a short read we start with find_task_by_pid.
 *
 * In the case of a seek we start with the leader and walk nr
 * threads past it.
 */
static struct task_struct *first_tid(struct task_struct *leader,
                                        int tid, int nr)
{
        struct task_struct *pos;

        rcu_read_lock();
        /* Attempt to start with the pid of a thread */
        if (tid && (nr > 0)) {
                pos = find_task_by_pid(tid);
                if (pos && (pos->group_leader == leader))
                        goto found;
        }

        /* If nr exceeds the number of threads there is nothing todo */
        pos = NULL;
        if (nr && nr >= get_nr_threads(leader))
                goto out;

        /* If we haven't found our starting place yet start
         * with the leader and walk nr threads forward.
         */
        for (pos = leader; nr > 0; --nr) {
                pos = next_thread(pos);
                if (pos == leader) {
                        pos = NULL;
                        goto out;
                }
        }
found:
        get_task_struct(pos);
out:
        rcu_read_unlock();
        return pos;
}

/*
 * Find the next thread in the thread list.
 * Return NULL if there is an error or no next thread.
 *
 * The reference to the input task_struct is released.
 */
static struct task_struct *next_tid(struct task_struct *start)
{
        struct task_struct *pos = NULL;
        rcu_read_lock();
        if (pid_alive(start)) {
                pos = next_thread(start);
                if (thread_group_leader(pos))
                        pos = NULL;
                else
                        get_task_struct(pos);
        }
        rcu_read_unlock();
        put_task_struct(start);
        return pos;
}

/* for the /proc/TGID/task/ directories */
static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
        char buf[PROC_NUMBUF];
        struct dentry *dentry = filp->f_dentry;
        struct inode *inode = dentry->d_inode;
        struct task_struct *leader = get_proc_task(inode);
        struct task_struct *task;
        int retval = -ENOENT;
        ino_t ino;
        int tid;
        unsigned long pos = filp->f_pos;  /* avoiding "long long" filp->f_pos */

        if (!leader)
                goto out_no_task;
        retval = 0;

        switch (pos) {
        case 0:
                ino = inode->i_ino;
                if (filldir(dirent, ".", 1, pos, ino, DT_DIR) < 0)
                        goto out;
                pos++;
                /* fall through */
        case 1:
                ino = parent_ino(dentry);
                if (filldir(dirent, "..", 2, pos, ino, DT_DIR) < 0)
                        goto out;
                pos++;
                /* fall through */
        }

        /* f_version caches the tgid value that the last readdir call couldn't
         * return. lseek aka telldir automagically resets f_version to 0.
         */
        tid = filp->f_version;
        filp->f_version = 0;
        for (task = first_tid(leader, tid, pos - 2);
             task;
             task = next_tid(task), pos++) {
                int len;
                tid = task->pid;
                len = snprintf(buf, sizeof(buf), "%d", tid);
                ino = fake_ino(tid, PROC_TID_INO);
                if (filldir(dirent, buf, len, pos, ino, DT_DIR < 0)) {
                        /* returning this tgid failed, save it as the first
                         * pid for the next readir call */
                        filp->f_version = tid;
                        put_task_struct(task);
                        break;
                }
        }
out:
        filp->f_pos = pos;
        put_task_struct(leader);
out_no_task:
        return retval;
}

static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
        struct inode *inode = dentry->d_inode;
        struct task_struct *p = get_proc_task(inode);
        generic_fillattr(inode, stat);

        if (p) {
                rcu_read_lock();
                stat->nlink += get_nr_threads(p);
                rcu_read_unlock();
                put_task_struct(p);
        }

        return 0;
}