linux-kernel - [PATCH] tmpfs: clear S_ISGID when setting posix ACLs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <1483690375-40718-1-git-send-email-guzheng1@huawei.com>
Date:   Fri, 6 Jan 2017 16:12:55 +0800
From:   Gu Zheng <guzheng1@...wei.com>
To:     <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <viro@...iv.linux.org.uk>, <jack@...e.cz>
Subject: [PATCH] tmpfs: clear S_ISGID when setting posix ACLs

This change was missed the tmpfs modification in In CVE-2016-7097
commit 073931017b49d9458aa351605b43a7e34598caef
posix_acl: Clear SGID bit when setting file permissions.
It can test by xfstest generic/375, which failed to clear
setgid bit in the following test case on tmpfs:

  touch $testfile
  chown 100:100 $testfile
  chmod 2755 $testfile
  _runas -u 100 -g 101 -- setfacl -m u::rwx,g::rwx,o::rwx $testfile

Signed-off-by: Gu Zheng <guzheng1@...wei.com>
---
 fs/posix_acl.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 5955220..d014dff 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -922,11 +922,10 @@ int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 	int error;
 
 	if (type == ACL_TYPE_ACCESS) {
-		error = posix_acl_equiv_mode(acl, &inode->i_mode);
-		if (error < 0)
-			return 0;
-		if (error == 0)
-			acl = NULL;
+		error = posix_acl_update_mode(inode,
+				&inode->i_mode, &acl);
+		if (error > 0)
+			return error;
 	}
 
 	inode->i_ctime = current_time(inode);
-- 
2.5.0