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