vfs: Make fs_parse() handle fs_param_is_fd-type params better

Make fs_parse() handle fs_param_is_fd-type parameters that are passed a
string by converting it to an integer (in addition to handling direct fd
specification).

Also range check the integer.

[fix from  Yin Fengwei folded]

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/fs_parser.c b/fs/fs_parser.c
index 460ea42..d1930ad 100644 (file)
--- a/fs/fs_parser.c
+++ b/fs/fs_parser.c
@@ -204,9 +204,23 @@ int fs_parse(struct fs_context *fc,
                goto okay;
 
        case fs_param_is_fd: {
-               if (param->type != fs_value_is_file)
+               switch (param->type) {
+               case fs_value_is_string:
+                       if (!result->has_value)
+                               goto bad_value;
+
+                       ret = kstrtouint(param->string, 0, &result->uint_32);
+                       break;
+               case fs_value_is_file:
+                       result->uint_32 = param->dirfd;
+                       ret = 0;
+               default:
                        goto bad_value;
-               goto okay;
+               }
+
+               if (result->uint_32 > INT_MAX)
+                       goto bad_value;
+               goto maybe_okay;
        }
 
        case fs_param_is_blockdev: