fs/ext4/xattr_security.c

   1 /*
   2  * linux/fs/ext4/xattr_security.c
   3  * Handler for storing security labels as extended attributes.
   4  */
   5
   6 #include <linux/module.h>
   7 #include <linux/string.h>
   8 #include <linux/fs.h>
   9 #include <linux/security.h>
  10 #include <linux/slab.h>
  11 #include "ext4_jbd2.h"
  12 #include "ext4.h"
  13 #include "xattr.h"
  14
  15 static size_t
  16 ext4_xattr_security_list(struct dentry *dentry, char *list, size_t list_size,
  17                 const char *name, size_t name_len, int type)
  18 {
  19         const size_t prefix_len = sizeof(XATTR_SECURITY_PREFIX)-1;
  20         const size_t total_len = prefix_len + name_len + 1;
  21
  22
  23         if (list && total_len <= list_size) {
  24                 memcpy(list, XATTR_SECURITY_PREFIX, prefix_len);
  25                 memcpy(list+prefix_len, name, name_len);
  26                 list[prefix_len + name_len] = '\0';
  27         }
  28         return total_len;
  29 }
  30
  31 static int
  32 ext4_xattr_security_get(struct dentry *dentry, const char *name,
  33                        void *buffer, size_t size, int type)
  34 {
  35         if (strcmp(name, "") == 0)
  36                 return -EINVAL;
  37         return ext4_xattr_get(dentry->d_inode, EXT4_XATTR_INDEX_SECURITY,
  38                               name, buffer, size);
  39 }
  40
  41 static int
  42 ext4_xattr_security_set(struct dentry *dentry, const char *name,
  43                 const void *value, size_t size, int flags, int type)
  44 {
  45         if (strcmp(name, "") == 0)
  46                 return -EINVAL;
  47         return ext4_xattr_set(dentry->d_inode, EXT4_XATTR_INDEX_SECURITY,
  48                               name, value, size, flags);
  49 }
  50
  51 int
  52 ext4_init_security(handle_t *handle, struct inode *inode, struct inode *dir)
  53 {
  54         int err;
  55         size_t len;
  56         void *value;
  57         char *name;
  58
  59         err = security_inode_init_security(inode, dir, &name, &value, &len);
  60         if (err) {
  61                 if (err == -EOPNOTSUPP)
  62                         return 0;
  63                 return err;
  64         }
  65         err = ext4_xattr_set_handle(handle, inode, EXT4_XATTR_INDEX_SECURITY,
  66                                     name, value, len, 0);
  67         kfree(name);
  68         kfree(value);
  69         return err;
  70 }
  71
  72 struct xattr_handler ext4_xattr_security_handler = {
  73         .prefix = XATTR_SECURITY_PREFIX,
  74         .list   = ext4_xattr_security_list,
  75         .get    = ext4_xattr_security_get,
  76         .set    = ext4_xattr_security_set,
  77 };