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(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(value, size);
  81                 if (IS_ERR(acl))
  82                         return PTR_ERR(acl);
  83         }
  84         if (acl) {
  85                 error = posix_acl_valid(acl);
  86                 if (error)
  87                         goto failed;
  88                 switch (type) {
  89                 case ACL_TYPE_ACCESS: {
  90                         struct posix_acl *saved_acl = acl;
  91
  92                         error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
  93                         if (acl == NULL)
  94                                 posix_acl_release(saved_acl);
  95                         if (error)
  96                                 goto failed;
  97                         inode->i_ctime = CURRENT_TIME;
  98                         break;
  99                 }
 100                 case ACL_TYPE_DEFAULT:
 101                         if (!S_ISDIR(inode->i_mode)) {
 102                                 error = -EINVAL;
 103                                 goto failed;
 104                         }
 105                         break;
 106                 }
 107         }
 108         set_cached_acl(inode, type, acl);
 109         error = 0;
 110 failed:
 111         posix_acl_release(acl);
 112         return error;
 113 }
 114
 115 /**
 116  * generic_acl_init  -  Take care of acl inheritance at @inode create time
 117  *
 118  * Files created inside a directory with a default ACL inherit the
 119  * directory's default ACL.
 120  */
 121 int
 122 generic_acl_init(struct inode *inode, struct inode *dir)
 123 {
 124         struct posix_acl *acl = NULL;
 125         int error;
 126
 127         if (!S_ISLNK(inode->i_mode))
 128                 acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);
 129         if (acl) {
 130                 if (S_ISDIR(inode->i_mode))
 131                         set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
 132                 error = posix_acl_create(&acl, GFP_KERNEL, &inode->i_mode);
 133                 if (error < 0)
 134                         return error;
 135                 if (error > 0)
 136                         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 137         } else {
 138                 inode->i_mode &= ~current_umask();
 139         }
 140         error = 0;
 141
 142         posix_acl_release(acl);
 143         return error;
 144 }
 145
 146 /**
 147  * generic_acl_chmod  -  change the access acl of @inode upon chmod()
 148  *
 149  * A chmod also changes the permissions of the owner, group/mask, and
 150  * other ACL entries.
 151  */
 152 int
 153 generic_acl_chmod(struct inode *inode)
 154 {
 155         struct posix_acl *acl;
 156         int error = 0;
 157
 158         if (S_ISLNK(inode->i_mode))
 159                 return -EOPNOTSUPP;
 160         acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
 161         if (acl) {
 162                 error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 163                 if (error)
 164                         return error;
 165                 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 166                 posix_acl_release(acl);
 167         }
 168         return error;
 169 }
 170
 171 const struct xattr_handler generic_acl_access_handler = {
 172         .prefix = POSIX_ACL_XATTR_ACCESS,
 173         .flags  = ACL_TYPE_ACCESS,
 174         .list   = generic_acl_list,
 175         .get    = generic_acl_get,
 176         .set    = generic_acl_set,
 177 };
 178
 179 const struct xattr_handler generic_acl_default_handler = {
 180         .prefix = POSIX_ACL_XATTR_DEFAULT,
 181         .flags  = ACL_TYPE_DEFAULT,
 182         .list   = generic_acl_list,
 183         .get    = generic_acl_get,
 184         .set    = generic_acl_set,
 185 };