fs/generic_acl.c

   1 /*
   2  * (C) 2005 Andreas Gruenbacher <agruen@suse.de>
   3  *
   4  * This file is released under the GPL.
   5  *
   6  * Generic ACL support for in-memory filesystems.
   7  */
   8
   9 #include <linux/sched.h>
  10 #include <linux/gfp.h>
  11 #include <linux/fs.h>
  12 #include <linux/generic_acl.h>
  13 #include <linux/posix_acl.h>
  14 #include <linux/posix_acl_xattr.h>
  15
  16
  17 static size_t
  18 generic_acl_list(struct dentry *dentry, char *list, size_t list_size,
  19                 const char *name, size_t name_len, int type)
  20 {
  21         struct posix_acl *acl;
  22         const char *xname;
  23         size_t size;
  24
  25         acl = get_cached_acl(dentry->d_inode, type);
  26         if (!acl)
  27                 return 0;
  28         posix_acl_release(acl);
  29
  30         switch (type) {
  31         case ACL_TYPE_ACCESS:
  32                 xname = POSIX_ACL_XATTR_ACCESS;
  33                 break;
  34         case ACL_TYPE_DEFAULT:
  35                 xname = POSIX_ACL_XATTR_DEFAULT;
  36                 break;
  37         default:
  38                 return 0;
  39         }
  40         size = strlen(xname) + 1;
  41         if (list && size <= list_size)
  42                 memcpy(list, xname, size);
  43         return size;
  44 }
  45
  46 static int
  47 generic_acl_get(struct dentry *dentry, const char *name, void *buffer,
  48                      size_t size, int type)
  49 {
  50         struct posix_acl *acl;
  51         int error;
  52
  53         if (strcmp(name, "") != 0)
  54                 return -EINVAL;
  55
  56         acl = get_cached_acl(dentry->d_inode, type);
  57         if (!acl)
  58                 return -ENODATA;
  59         error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
  60         posix_acl_release(acl);
  61
  62         return error;
  63 }
  64
  65 static int
  66 generic_acl_set(struct dentry *dentry, const char *name, const void *value,
  67                      size_t size, int flags, int type)
  68 {
  69         struct inode *inode = dentry->d_inode;
  70         struct posix_acl *acl = NULL;
  71         int error;
  72
  73         if (strcmp(name, "") != 0)
  74                 return -EINVAL;
  75         if (S_ISLNK(inode->i_mode))
  76                 return -EOPNOTSUPP;
  77         if (!inode_owner_or_capable(inode))
  78                 return -EPERM;
  79         if (value) {
  80                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
  81                 if (IS_ERR(acl))
  82                         return PTR_ERR(acl);
  83         }
  84         if (acl) {
  85                 struct posix_acl *old_acl;
  86
  87                 error = posix_acl_valid(acl);
  88                 if (error)
  89                         goto failed;
  90                 switch (type) {
  91                 case ACL_TYPE_ACCESS:
  92                         old_acl = acl;
  93                         error = posix_acl_update_mode(inode, &inode->i_mode,
  94                                                       &acl);
  95                         if (error < 0)
  96                                 goto failed;
  97                         if (!acl)
  98                                 posix_acl_release(old_acl);
  99                         inode->i_ctime = CURRENT_TIME;
 100                         break;
 101                 case ACL_TYPE_DEFAULT:
 102                         if (!S_ISDIR(inode->i_mode)) {
 103                                 error = -EINVAL;
 104                                 goto failed;
 105                         }
 106                         break;
 107                 }
 108         }
 109         set_cached_acl(inode, type, acl);
 110         error = 0;
 111 failed:
 112         posix_acl_release(acl);
 113         return error;
 114 }
 115
 116 /**
 117  * generic_acl_init  -  Take care of acl inheritance at @inode create time
 118  *
 119  * Files created inside a directory with a default ACL inherit the
 120  * directory's default ACL.
 121  */
 122 int
 123 generic_acl_init(struct inode *inode, struct inode *dir)
 124 {
 125         struct posix_acl *acl = NULL;
 126         int error;
 127
 128         if (!S_ISLNK(inode->i_mode))
 129                 acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);
 130         if (acl) {
 131                 if (S_ISDIR(inode->i_mode))
 132                         set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
 133                 error = posix_acl_create(&acl, GFP_KERNEL, &inode->i_mode);
 134                 if (error < 0)
 135                         return error;
 136                 if (error > 0)
 137                         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 138         } else {
 139                 inode->i_mode &= ~current_umask();
 140         }
 141         error = 0;
 142
 143         posix_acl_release(acl);
 144         return error;
 145 }
 146
 147 /**
 148  * generic_acl_chmod  -  change the access acl of @inode upon chmod()
 149  *
 150  * A chmod also changes the permissions of the owner, group/mask, and
 151  * other ACL entries.
 152  */
 153 int
 154 generic_acl_chmod(struct inode *inode)
 155 {
 156         struct posix_acl *acl;
 157         int error = 0;
 158
 159         if (S_ISLNK(inode->i_mode))
 160                 return -EOPNOTSUPP;
 161         acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
 162         if (acl) {
 163                 error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 164                 if (error)
 165                         return error;
 166                 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 167                 posix_acl_release(acl);
 168         }
 169         return error;
 170 }
 171
 172 const struct xattr_handler generic_acl_access_handler = {
 173         .prefix = POSIX_ACL_XATTR_ACCESS,
 174         .flags  = ACL_TYPE_ACCESS,
 175         .list   = generic_acl_list,
 176         .get    = generic_acl_get,
 177         .set    = generic_acl_set,
 178 };
 179
 180 const struct xattr_handler generic_acl_default_handler = {
 181         .prefix = POSIX_ACL_XATTR_DEFAULT,
 182         .flags  = ACL_TYPE_DEFAULT,
 183         .list   = generic_acl_list,
 184         .get    = generic_acl_get,
 185         .set    = generic_acl_set,
 186 };