[PATCH v19 4/4] overlayfs: inode_owner_or_capable called during execv

[David Anderson]

From: John Stultz <john.stultz at linaro.org>

Using old_creds as an indication that we are not overriding the
credentials, bypass call to inode_owner_or_capable.  This solves
a problem with all execv calls being blocked when using the caller's
credentials.

Signed-off-by: John Stultz <john.stultz at linaro.org>
Signed-off-by: Mark Salyzyn <salyzyn at android.com>
Signed-off-by: David Anderson <dvander at google.com>
Fixes: 05acefb4872da ("ovl: check permission to open real file")
Cc: linux-fsdevel at vger.kernel.org
Cc: linux-unionfs at vger.kernel.org
Cc: Stephen Smalley <sds at tycho.nsa.gov>
Cc: linux-kernel at vger.kernel.org
Cc: linux-security-module at vger.kernel.org
Cc: kernel-team at android.com
Cc: selinux at vger.kernel.org
Cc: paulmoore at microsoft.com
Cc: Luca.Boccassi at microsoft.com

v19 - rebase

v18 - rebase

v17 - rebase

v16 - introduced fix over rebased series
---
 fs/overlayfs/file.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 11d8277c94cd..586de55bba79 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -55,7 +55,8 @@ static struct file *ovl_open_realfile(const struct file *file,
 	if (err) {
 		realfile = ERR_PTR(err);
 	} else {
-		if (!inode_owner_or_capable(&init_user_ns, realinode))
+		if (old_cred && !inode_owner_or_capable(&init_user_ns,
+							realinode))
 			flags &= ~O_NOATIME;
 
 		realfile = open_with_fake_path(&file->f_path, flags, realinode,
-- 
2.34.0.rc1.387.gb447b232ab-goog