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   1 /*
   2  * mm/shmem_acl.c
   3  *
   4  * (C) 2005 Andreas Gruenbacher <agruen@suse.de>
   5  *
   6  * This file is released under the GPL.
   7  */
   8
   9 #include <linux/fs.h>
  10 #include <linux/shmem_fs.h>
  11 #include <linux/xattr.h>
  12 #include <linux/generic_acl.h>
  13
  14 /**
  15  * shmem_get_acl  -   generic_acl_operations->getacl() operation
  16  */
  17 static struct posix_acl *
  18 shmem_get_acl(struct inode *inode, int type)
  19 {
  20         struct posix_acl *acl = NULL;
  21
  22         spin_lock(&inode->i_lock);
  23         switch(type) {
  24                 case ACL_TYPE_ACCESS:
  25                         acl = posix_acl_dup(SHMEM_I(inode)->i_acl);
  26                         break;
  27
  28                 case ACL_TYPE_DEFAULT:
  29                         acl = posix_acl_dup(SHMEM_I(inode)->i_default_acl);
  30                         break;
  31         }
  32         spin_unlock(&inode->i_lock);
  33
  34         return acl;
  35 }
  36
  37 /**
  38  * shmem_set_acl  -   generic_acl_operations->setacl() operation
  39  */
  40 static void
  41 shmem_set_acl(struct inode *inode, int type, struct posix_acl *acl)
  42 {
  43         struct posix_acl *free = NULL;
  44
  45         spin_lock(&inode->i_lock);
  46         switch(type) {
  47                 case ACL_TYPE_ACCESS:
  48                         free = SHMEM_I(inode)->i_acl;
  49                         SHMEM_I(inode)->i_acl = posix_acl_dup(acl);
  50                         break;
  51
  52                 case ACL_TYPE_DEFAULT:
  53                         free = SHMEM_I(inode)->i_default_acl;
  54                         SHMEM_I(inode)->i_default_acl = posix_acl_dup(acl);
  55                         break;
  56         }
  57         spin_unlock(&inode->i_lock);
  58         posix_acl_release(free);
  59 }
  60
  61 struct generic_acl_operations shmem_acl_ops = {
  62         .getacl = shmem_get_acl,
  63         .setacl = shmem_set_acl,
  64 };
  65
  66 /**
  67  * shmem_list_acl_access, shmem_get_acl_access, shmem_set_acl_access,
  68  * shmem_xattr_acl_access_handler  -  plumbing code to implement the
  69  * system.posix_acl_access xattr using the generic acl functions.
  70  */
  71
  72 static size_t
  73 shmem_list_acl_access(struct inode *inode, char *list, size_t list_size,
  74                       const char *name, size_t name_len)
  75 {
  76         return generic_acl_list(inode, &shmem_acl_ops, ACL_TYPE_ACCESS,
  77                                 list, list_size);
  78 }
  79
  80 static int
  81 shmem_get_acl_access(struct inode *inode, const char *name, void *buffer,
  82                      size_t size)
  83 {
  84         if (strcmp(name, "") != 0)
  85                 return -EINVAL;
  86         return generic_acl_get(inode, &shmem_acl_ops, ACL_TYPE_ACCESS, buffer,
  87                                size);
  88 }
  89
  90 static int
  91 shmem_set_acl_access(struct inode *inode, const char *name, const void *value,
  92                      size_t size, int flags)
  93 {
  94         if (strcmp(name, "") != 0)
  95                 return -EINVAL;
  96         return generic_acl_set(inode, &shmem_acl_ops, ACL_TYPE_ACCESS, value,
  97                                size);
  98 }
  99
 100 struct xattr_handler shmem_xattr_acl_access_handler = {
 101         .prefix = POSIX_ACL_XATTR_ACCESS,
 102         .list   = shmem_list_acl_access,
 103         .get    = shmem_get_acl_access,
 104         .set    = shmem_set_acl_access,
 105 };
 106
 107 /**
 108  * shmem_list_acl_default, shmem_get_acl_default, shmem_set_acl_default,
 109  * shmem_xattr_acl_default_handler  -  plumbing code to implement the
 110  * system.posix_acl_default xattr using the generic acl functions.
 111  */
 112
 113 static size_t
 114 shmem_list_acl_default(struct inode *inode, char *list, size_t list_size,
 115                        const char *name, size_t name_len)
 116 {
 117         return generic_acl_list(inode, &shmem_acl_ops, ACL_TYPE_DEFAULT,
 118                                 list, list_size);
 119 }
 120
 121 static int
 122 shmem_get_acl_default(struct inode *inode, const char *name, void *buffer,
 123                       size_t size)
 124 {
 125         if (strcmp(name, "") != 0)
 126                 return -EINVAL;
 127         return generic_acl_get(inode, &shmem_acl_ops, ACL_TYPE_DEFAULT, buffer,
 128                                size);
 129 }
 130
 131 static int
 132 shmem_set_acl_default(struct inode *inode, const char *name, const void *value,
 133                       size_t size, int flags)
 134 {
 135         if (strcmp(name, "") != 0)
 136                 return -EINVAL;
 137         return generic_acl_set(inode, &shmem_acl_ops, ACL_TYPE_DEFAULT, value,
 138                                size);
 139 }
 140
 141 struct xattr_handler shmem_xattr_acl_default_handler = {
 142         .prefix = POSIX_ACL_XATTR_DEFAULT,
 143         .list   = shmem_list_acl_default,
 144         .get    = shmem_get_acl_default,
 145         .set    = shmem_set_acl_default,
 146 };
 147
 148 /**
 149  * shmem_acl_init  -  Inizialize the acl(s) of a new inode
 150  */
 151 int
 152 shmem_acl_init(struct inode *inode, struct inode *dir)
 153 {
 154         return generic_acl_init(inode, dir, &shmem_acl_ops);
 155 }
 156
 157 /**
 158  * shmem_acl_destroy_inode  -  destroy acls hanging off the in-memory inode
 159  *
 160  * This is done before destroying the actual inode.
 161  */
 162
 163 void
 164 shmem_acl_destroy_inode(struct inode *inode)
 165 {
 166         if (SHMEM_I(inode)->i_acl)
 167                 posix_acl_release(SHMEM_I(inode)->i_acl);
 168         SHMEM_I(inode)->i_acl = NULL;
 169         if (SHMEM_I(inode)->i_default_acl)
 170                 posix_acl_release(SHMEM_I(inode)->i_default_acl);
 171         SHMEM_I(inode)->i_default_acl = NULL;
 172 }
 173
 174 /**
 175  * shmem_check_acl  -  check_acl() callback for generic_permission()
 176  */
 177 static int
 178 shmem_check_acl(struct inode *inode, int mask)
 179 {
 180         struct posix_acl *acl = shmem_get_acl(inode, ACL_TYPE_ACCESS);
 181
 182         if (acl) {
 183                 int error = posix_acl_permission(inode, acl, mask);
 184                 posix_acl_release(acl);
 185                 return error;
 186         }
 187         return -EAGAIN;
 188 }
 189
 190 /**
 191  * shmem_permission  -  permission() inode operation
 192  */
 193 int
 194 shmem_permission(struct inode *inode, int mask, struct nameidata *nd)
 195 {
 196         return generic_permission(inode, mask, shmem_check_acl);
 197 }