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                 mode_t mode;
  86
  87                 error = posix_acl_valid(acl);
  88                 if (error)
  89                         goto failed;
  90                 switch (type) {
  91                 case ACL_TYPE_ACCESS:
  92                         mode = inode->i_mode;
  93                         error = posix_acl_equiv_mode(acl, &mode);
  94                         if (error < 0)
  95                                 goto failed;
  96                         inode->i_mode = mode;
  97                         inode->i_ctime = CURRENT_TIME;
  98                         if (error == 0) {
  99                                 posix_acl_release(acl);
 100                                 acl = NULL;
 101                         }
 102                         break;
 103                 case ACL_TYPE_DEFAULT:
 104                         if (!S_ISDIR(inode->i_mode)) {
 105                                 error = -EINVAL;
 106                                 goto failed;
 107                         }
 108                         break;
 109                 }
 110         }
 111         set_cached_acl(inode, type, acl);
 112         error = 0;
 113 failed:
 114         posix_acl_release(acl);
 115         return error;
 116 }
 117
 118 /**
 119  * generic_acl_init  -  Take care of acl inheritance at @inode create time
 120  *
 121  * Files created inside a directory with a default ACL inherit the
 122  * directory's default ACL.
 123  */
 124 int
 125 generic_acl_init(struct inode *inode, struct inode *dir)
 126 {
 127         struct posix_acl *acl = NULL;
 128         mode_t mode = inode->i_mode;
 129         int error;
 130
 131         inode->i_mode = mode & ~current_umask();
 132         if (!S_ISLNK(inode->i_mode))
 133                 acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);
 134         if (acl) {
 135                 struct posix_acl *clone;
 136
 137                 if (S_ISDIR(inode->i_mode)) {
 138                         clone = posix_acl_clone(acl, GFP_KERNEL);
 139                         error = -ENOMEM;
 140                         if (!clone)
 141                                 goto cleanup;
 142                         set_cached_acl(inode, ACL_TYPE_DEFAULT, clone);
 143                         posix_acl_release(clone);
 144                 }
 145                 clone = posix_acl_clone(acl, GFP_KERNEL);
 146                 error = -ENOMEM;
 147                 if (!clone)
 148                         goto cleanup;
 149                 error = posix_acl_create_masq(clone, &mode);
 150                 if (error >= 0) {
 151                         inode->i_mode = mode;
 152                         if (error > 0)
 153                                 set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
 154                 }
 155                 posix_acl_release(clone);
 156         }
 157         error = 0;
 158
 159 cleanup:
 160         posix_acl_release(acl);
 161         return error;
 162 }
 163
 164 /**
 165  * generic_acl_chmod  -  change the access acl of @inode upon chmod()
 166  *
 167  * A chmod also changes the permissions of the owner, group/mask, and
 168  * other ACL entries.
 169  */
 170 int
 171 generic_acl_chmod(struct inode *inode)
 172 {
 173         struct posix_acl *acl, *clone;
 174         int error = 0;
 175
 176         if (S_ISLNK(inode->i_mode))
 177                 return -EOPNOTSUPP;
 178         acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
 179         if (acl) {
 180                 clone = posix_acl_clone(acl, GFP_KERNEL);
 181                 posix_acl_release(acl);
 182                 if (!clone)
 183                         return -ENOMEM;
 184                 error = posix_acl_chmod_masq(clone, inode->i_mode);
 185                 if (!error)
 186                         set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
 187                 posix_acl_release(clone);
 188         }
 189         return error;
 190 }
 191
 192 int
 193 generic_check_acl(struct inode *inode, int mask)
 194 {
 195         if (mask & MAY_NOT_BLOCK) {
 196                 if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
 197                         return -ECHILD;
 198         } else {
 199                 struct posix_acl *acl;
 200
 201                 acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
 202                 if (acl) {
 203                         int error = posix_acl_permission(inode, acl, mask);
 204                         posix_acl_release(acl);
 205                         return error;
 206                 }
 207         }
 208         return -EAGAIN;
 209 }
 210
 211 const struct xattr_handler generic_acl_access_handler = {
 212         .prefix = POSIX_ACL_XATTR_ACCESS,
 213         .flags  = ACL_TYPE_ACCESS,
 214         .list   = generic_acl_list,
 215         .get    = generic_acl_get,
 216         .set    = generic_acl_set,
 217 };
 218
 219 const struct xattr_handler generic_acl_default_handler = {
 220         .prefix = POSIX_ACL_XATTR_DEFAULT,
 221         .flags  = ACL_TYPE_DEFAULT,
 222         .list   = generic_acl_list,
 223         .get    = generic_acl_get,
 224         .set    = generic_acl_set,
 225 };