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