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   1 /*
   2  * fs/generic_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/sched.h>
  10 #include <linux/fs.h>
  11 #include <linux/generic_acl.h>
  12
  13 /**
  14  * generic_acl_list  -  Generic xattr_handler->list() operation
  15  * @ops:        Filesystem specific getacl and setacl callbacks
  16  */
  17 size_t
  18 generic_acl_list(struct inode *inode, struct generic_acl_operations *ops,
  19                  int type, char *list, size_t list_size)
  20 {
  21         struct posix_acl *acl;
  22         const char *name;
  23         size_t size;
  24
  25         acl = ops->getacl(inode, type);
  26         if (!acl)
  27                 return 0;
  28         posix_acl_release(acl);
  29
  30         switch(type) {
  31                 case ACL_TYPE_ACCESS:
  32                         name = POSIX_ACL_XATTR_ACCESS;
  33                         break;
  34
  35                 case ACL_TYPE_DEFAULT:
  36                         name = POSIX_ACL_XATTR_DEFAULT;
  37                         break;
  38
  39                 default:
  40                         return 0;
  41         }
  42         size = strlen(name) + 1;
  43         if (list && size <= list_size)
  44                 memcpy(list, name, size);
  45         return size;
  46 }
  47
  48 /**
  49  * generic_acl_get  -  Generic xattr_handler->get() operation
  50  * @ops:        Filesystem specific getacl and setacl callbacks
  51  */
  52 int
  53 generic_acl_get(struct inode *inode, struct generic_acl_operations *ops,
  54                 int type, void *buffer, size_t size)
  55 {
  56         struct posix_acl *acl;
  57         int error;
  58
  59         acl = ops->getacl(inode, type);
  60         if (!acl)
  61                 return -ENODATA;
  62         error = posix_acl_to_xattr(acl, buffer, size);
  63         posix_acl_release(acl);
  64
  65         return error;
  66 }
  67
  68 /**
  69  * generic_acl_set  -  Generic xattr_handler->set() operation
  70  * @ops:        Filesystem specific getacl and setacl callbacks
  71  */
  72 int
  73 generic_acl_set(struct inode *inode, struct generic_acl_operations *ops,
  74                 int type, const void *value, size_t size)
  75 {
  76         struct posix_acl *acl = NULL;
  77         int error;
  78
  79         if (S_ISLNK(inode->i_mode))
  80                 return -EOPNOTSUPP;
  81         if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
  82                 return -EPERM;
  83         if (value) {
  84                 acl = posix_acl_from_xattr(value, size);
  85                 if (IS_ERR(acl))
  86                         return PTR_ERR(acl);
  87         }
  88         if (acl) {
  89                 mode_t mode;
  90
  91                 error = posix_acl_valid(acl);
  92                 if (error)
  93                         goto failed;
  94                 switch(type) {
  95                         case ACL_TYPE_ACCESS:
  96                                 mode = inode->i_mode;
  97                                 error = posix_acl_equiv_mode(acl, &mode);
  98                                 if (error < 0)
  99                                         goto failed;
 100                                 inode->i_mode = mode;
 101                                 if (error == 0) {
 102                                         posix_acl_release(acl);
 103                                         acl = NULL;
 104                                 }
 105                                 break;
 106
 107                         case ACL_TYPE_DEFAULT:
 108                                 if (!S_ISDIR(inode->i_mode)) {
 109                                         error = -EINVAL;
 110                                         goto failed;
 111                                 }
 112                                 break;
 113                 }
 114         }
 115         ops->setacl(inode, type, acl);
 116         error = 0;
 117 failed:
 118         posix_acl_release(acl);
 119         return error;
 120 }
 121
 122 /**
 123  * generic_acl_init  -  Take care of acl inheritance at @inode create time
 124  * @ops:        Filesystem specific getacl and setacl callbacks
 125  *
 126  * Files created inside a directory with a default ACL inherit the
 127  * directory's default ACL.
 128  */
 129 int
 130 generic_acl_init(struct inode *inode, struct inode *dir,
 131                  struct generic_acl_operations *ops)
 132 {
 133         struct posix_acl *acl = NULL;
 134         mode_t mode = inode->i_mode;
 135         int error;
 136
 137         inode->i_mode = mode & ~current->fs->umask;
 138         if (!S_ISLNK(inode->i_mode))
 139                 acl = ops->getacl(dir, ACL_TYPE_DEFAULT);
 140         if (acl) {
 141                 struct posix_acl *clone;
 142
 143                 if (S_ISDIR(inode->i_mode)) {
 144                         clone = posix_acl_clone(acl, GFP_KERNEL);
 145                         error = -ENOMEM;
 146                         if (!clone)
 147                                 goto cleanup;
 148                         ops->setacl(inode, ACL_TYPE_DEFAULT, clone);
 149                         posix_acl_release(clone);
 150                 }
 151                 clone = posix_acl_clone(acl, GFP_KERNEL);
 152                 error = -ENOMEM;
 153                 if (!clone)
 154                         goto cleanup;
 155                 error = posix_acl_create_masq(clone, &mode);
 156                 if (error >= 0) {
 157                         inode->i_mode = mode;
 158                         if (error > 0)
 159                                 ops->setacl(inode, ACL_TYPE_ACCESS, clone);
 160                 }
 161                 posix_acl_release(clone);
 162         }
 163         error = 0;
 164
 165 cleanup:
 166         posix_acl_release(acl);
 167         return error;
 168 }
 169
 170 /**
 171  * generic_acl_chmod  -  change the access acl of @inode upon chmod()
 172  * @ops:        FIlesystem specific getacl and setacl callbacks
 173  *
 174  * A chmod also changes the permissions of the owner, group/mask, and
 175  * other ACL entries.
 176  */
 177 int
 178 generic_acl_chmod(struct inode *inode, struct generic_acl_operations *ops)
 179 {
 180         struct posix_acl *acl, *clone;
 181         int error = 0;
 182
 183         if (S_ISLNK(inode->i_mode))
 184                 return -EOPNOTSUPP;
 185         acl = ops->getacl(inode, ACL_TYPE_ACCESS);
 186         if (acl) {
 187                 clone = posix_acl_clone(acl, GFP_KERNEL);
 188                 posix_acl_release(acl);
 189                 if (!clone)
 190                         return -ENOMEM;
 191                 error = posix_acl_chmod_masq(clone, inode->i_mode);
 192                 if (!error)
 193                         ops->setacl(inode, ACL_TYPE_ACCESS, clone);
 194                 posix_acl_release(clone);
 195         }
 196         return error;
 197 }