linux-kernel - [PATCH 30/43] userns: Fail exec for suid and sgid binaries with ids outside our user namespace.

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Message-Id: <1333862139-31737-30-git-send-email-ebiederm@xmission.com>
Date:	Sat,  7 Apr 2012 22:15:26 -0700
From:	"\"Eric W. Beiderman" <ebiederm@...ssion.com>
To:	<linux-kernel@...r.kernel.org>
Cc:	<linux-fsdevel@...r.kernel.org>,
	<linux-security-module@...r.kernel.org>,
	Linux Containers <containers@...ts.linux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Al Viro <viro@...IV.linux.org.uk>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH 30/43] userns: Fail exec for suid and sgid binaries with ids outside our user namespace.

From: Eric W. Biederman <ebiederm@...ssion.com>

Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---
 fs/exec.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 00ae2ef..e001bdf 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1291,8 +1291,11 @@ int prepare_binprm(struct linux_binprm *bprm)
 	if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
 		/* Set-uid? */
 		if (mode & S_ISUID) {
+			if (!kuid_has_mapping(bprm->cred->user_ns, inode->i_uid))
+				return -EPERM;
 			bprm->per_clear |= PER_CLEAR_ON_SETID;
 			bprm->cred->euid = inode->i_uid;
+
 		}
 
 		/* Set-gid? */
@@ -1302,6 +1305,8 @@ int prepare_binprm(struct linux_binprm *bprm)
 		 * executable.
 		 */
 		if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
+			if (!kgid_has_mapping(bprm->cred->user_ns, inode->i_gid))
+				return -EPERM;
 			bprm->per_clear |= PER_CLEAR_ON_SETID;
 			bprm->cred->egid = inode->i_gid;
 		}
-- 
1.7.2.5

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