kernel/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/string.h>
   7 #include <linux/fs.h>
   8 #include <linux/security.h>
   9 #include <linux/slab.h>
  10 #include "ext4_jbd2.h"
  11 #include "ext4.h"
  12 #include "xattr.h"
  13
  14 static size_t
  15 ext4_xattr_security_list(const struct xattr_handler *handler,
  16                          struct dentry *dentry, char *list, size_t list_size,
  17                          const char *name, size_t name_len)
  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(const struct xattr_handler *handler,
  33                         struct dentry *dentry, const char *name,
  34                         void *buffer, size_t size)
  35 {
  36         if (strcmp(name, "") == 0)
  37                 return -EINVAL;
  38         return ext4_xattr_get(d_inode(dentry), EXT4_XATTR_INDEX_SECURITY,
  39                               name, buffer, size);
  40 }
  41
  42 static int
  43 ext4_xattr_security_set(const struct xattr_handler *handler,
  44                         struct dentry *dentry, const char *name,
  45                         const void *value, size_t size, int flags)
  46 {
  47         if (strcmp(name, "") == 0)
  48                 return -EINVAL;
  49         return ext4_xattr_set(d_inode(dentry), EXT4_XATTR_INDEX_SECURITY,
  50                               name, value, size, flags);
  51 }
  52
  53 static int
  54 ext4_initxattrs(struct inode *inode, const struct xattr *xattr_array,
  55                 void *fs_info)
  56 {
  57         const struct xattr *xattr;
  58         handle_t *handle = fs_info;
  59         int err = 0;
  60
  61         for (xattr = xattr_array; xattr->name != NULL; xattr++) {
  62                 err = ext4_xattr_set_handle(handle, inode,
  63                                             EXT4_XATTR_INDEX_SECURITY,
  64                                             xattr->name, xattr->value,
  65                                             xattr->value_len, 0);
  66                 if (err < 0)
  67                         break;
  68         }
  69         return err;
  70 }
  71
  72 int
  73 ext4_init_security(handle_t *handle, struct inode *inode, struct inode *dir,
  74                    const struct qstr *qstr)
  75 {
  76         return security_inode_init_security(inode, dir, qstr,
  77                                             &ext4_initxattrs, handle);
  78 }
  79
  80 const struct xattr_handler ext4_xattr_security_handler = {
  81         .prefix = XATTR_SECURITY_PREFIX,
  82         .list   = ext4_xattr_security_list,
  83         .get    = ext4_xattr_security_get,
  84         .set    = ext4_xattr_security_set,
  85 };