[review,05/12] cred: Reject inodes with invalid ids in set_create_file_as()

Commit Message

Eric W. Biederman July 6, 2016, 6:12 p.m. UTC

From: Seth Forshee <[e-mail]>

Using INVALID_[UG]ID for the LSM file creation context doesn't
make sense, so return an error if the inode passed to
set_create_file_as() has an invalid id.

Signed-off-by: Seth Forshee <[e-mail]>
Acked-by: Serge Hallyn <[e-mail]>
Signed-off-by: Eric W. Biederman <[e-mail]>
---
 kernel/cred.c | 2 ++
 1 file changed, 2 insertions(+)

Patch

diff --git a/kernel/cred.c b/kernel/cred.c
index 0c0cd8a62285..5f264fb5737d 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -689,6 +689,8 @@  EXPORT_SYMBOL(set_security_override_from_ctx);
  */
 int set_create_files_as(struct cred *new, struct inode *inode)
 {
+	if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid))
+		return -EINVAL;
 	new->fsuid = inode->i_uid;
 	new->fsgid = inode->i_gid;
 	return security_kernel_create_files_as(new, inode);