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   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/fs.h>
  11 #include <linux/generic_acl.h>
  12 #include <linux/posix_acl.h>
  13 #include <linux/posix_acl_xattr.h>
  14
  15
  16 static size_t
  17 generic_acl_list(struct dentry *dentry, char *list, size_t list_size,
  18                 const char *name, size_t name_len, int type)
  19 {
  20         struct posix_acl *acl;
  21         const char *xname;
  22         size_t size;
  23
  24         acl = get_cached_acl(dentry->d_inode, type);
  25         if (!acl)
  26                 return 0;
  27         posix_acl_release(acl);
  28
  29         switch (type) {
  30         case ACL_TYPE_ACCESS:
  31                 xname = POSIX_ACL_XATTR_ACCESS;
  32                 break;
  33         case ACL_TYPE_DEFAULT:
  34                 xname = POSIX_ACL_XATTR_DEFAULT;
  35                 break;
  36         default:
  37                 return 0;
  38         }
  39         size = strlen(xname) + 1;
  40         if (list && size <= list_size)
  41                 memcpy(list, xname, size);
  42         return size;
  43 }
  44
  45 static int
  46 generic_acl_get(struct dentry *dentry, const char *name, void *buffer,
  47                      size_t size, int type)
  48 {
  49         struct posix_acl *acl;
  50         int error;
  51
  52         if (strcmp(name, "") != 0)
  53                 return -EINVAL;
  54
  55         acl = get_cached_acl(dentry->d_inode, type);
  56         if (!acl)
  57                 return -ENODATA;
  58         error = posix_acl_to_xattr(acl, buffer, size);
  59         posix_acl_release(acl);
  60
  61         return error;
  62 }
  63
  64 static int
  65 generic_acl_set(struct dentry *dentry, const char *name, const void *value,
  66                      size_t size, int flags, int type)
  67 {
  68         struct inode *inode = dentry->d_inode;
  69         struct posix_acl *acl = NULL;
  70         int error;
  71
  72         if (strcmp(name, "") != 0)
  73                 return -EINVAL;
  74         if (S_ISLNK(inode->i_mode))
  75                 return -EOPNOTSUPP;
  76         if (!is_owner_or_cap(inode))
  77                 return -EPERM;
  78         if (value) {
  79                 acl = posix_acl_from_xattr(value, size);
  80                 if (IS_ERR(acl))
  81                         return PTR_ERR(acl);
  82         }
  83         if (acl) {
  84                 mode_t mode;
  85
  86                 error = posix_acl_valid(acl);
  87                 if (error)
  88                         goto failed;
  89                 switch (type) {
  90                 case ACL_TYPE_ACCESS:
  91                         mode = inode->i_mode;
  92                         error = posix_acl_equiv_mode(acl, &mode);
  93                         if (error < 0)
  94                                 goto failed;
  95                         inode->i_mode = mode;
  96                         if (error == 0) {
  97                                 posix_acl_release(acl);
  98                                 acl = NULL;
  99                         }
 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         mode_t mode = inode->i_mode;
 127         int error;
 128
 129         inode->i_mode = mode & ~current_umask();
 130         if (!S_ISLNK(inode->i_mode))
 131                 acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);
 132         if (acl) {
 133                 struct posix_acl *clone;
 134
 135                 if (S_ISDIR(inode->i_mode)) {
 136                         clone = posix_acl_clone(acl, GFP_KERNEL);
 137                         error = -ENOMEM;
 138                         if (!clone)
 139                                 goto cleanup;
 140                         set_cached_acl(inode, ACL_TYPE_DEFAULT, clone);
 141                         posix_acl_release(clone);
 142                 }
 143                 clone = posix_acl_clone(acl, GFP_KERNEL);
 144                 error = -ENOMEM;
 145                 if (!clone)
 146                         goto cleanup;
 147                 error = posix_acl_create_masq(clone, &mode);
 148                 if (error >= 0) {
 149                         inode->i_mode = mode;
 150                         if (error > 0)
 151                                 set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
 152                 }
 153                 posix_acl_release(clone);
 154         }
 155         error = 0;
 156
 157 cleanup:
 158         posix_acl_release(acl);
 159         return error;
 160 }
 161
 162 /**
 163  * generic_acl_chmod  -  change the access acl of @inode upon chmod()
 164  *
 165  * A chmod also changes the permissions of the owner, group/mask, and
 166  * other ACL entries.
 167  */
 168 int
 169 generic_acl_chmod(struct inode *inode)
 170 {
 171         struct posix_acl *acl, *clone;
 172         int error = 0;
 173
 174         if (S_ISLNK(inode->i_mode))
 175                 return -EOPNOTSUPP;
 176         acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
 177         if (acl) {
 178                 clone = posix_acl_clone(acl, GFP_KERNEL);
 179                 posix_acl_release(acl);
 180                 if (!clone)
 181                         return -ENOMEM;
 182                 error = posix_acl_chmod_masq(clone, inode->i_mode);
 183                 if (!error)
 184                         set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
 185                 posix_acl_release(clone);
 186         }
 187         return error;
 188 }
 189
 190 int
 191 generic_check_acl(struct inode *inode, int mask)
 192 {
 193         struct posix_acl *acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
 194
 195         if (acl) {
 196                 int error = posix_acl_permission(inode, acl, mask);
 197                 posix_acl_release(acl);
 198                 return error;
 199         }
 200         return -EAGAIN;
 201 }
 202
 203 struct xattr_handler generic_acl_access_handler = {
 204         .prefix = POSIX_ACL_XATTR_ACCESS,
 205         .flags  = ACL_TYPE_ACCESS,
 206         .list   = generic_acl_list,
 207         .get    = generic_acl_get,
 208         .set    = generic_acl_set,
 209 };
 210
 211 struct xattr_handler generic_acl_default_handler = {
 212         .prefix = POSIX_ACL_XATTR_DEFAULT,
 213         .flags  = ACL_TYPE_DEFAULT,
 214         .list   = generic_acl_list,
 215         .get    = generic_acl_get,
 216         .set    = generic_acl_set,
 217 };