linux-kernel - [PATCH v4 15/21] fs: Don't remove suid for CAP_FSETID in s_user

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Message-Id: <1461699396-33000-16-git-send-email-seth.forshee@canonical.com>
Date:	Tue, 26 Apr 2016 14:36:28 -0500
From:	Seth Forshee <seth.forshee@...onical.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Alexander Viro <viro@...iv.linux.org.uk>
Cc:	Serge Hallyn <serge.hallyn@...onical.com>,
	Richard Weinberger <richard.weinberger@...il.com>,
	Austin S Hemmelgarn <ahferroin7@...il.com>,
	Miklos Szeredi <mszeredi@...hat.com>,
	Pavel Tikhomirov <ptikhomirov@...tuozzo.com>,
	linux-kernel@...r.kernel.org, linux-bcache@...r.kernel.org,
	dm-devel@...hat.com, linux-raid@...r.kernel.org,
	linux-mtd@...ts.infradead.org, linux-fsdevel@...r.kernel.org,
	fuse-devel@...ts.sourceforge.net,
	linux-security-module@...r.kernel.org, selinux@...ho.nsa.gov,
	cgroups@...r.kernel.org, Seth Forshee <seth.forshee@...onical.com>
Subject: [PATCH v4 15/21] fs: Don't remove suid for CAP_FSETID in s_user_ns

Expand the check in should_remove_suid() to keep privileges for
CAP_FSETID in s_user_ns rather than init_user_ns.

Signed-off-by: Seth Forshee <seth.forshee@...onical.com>
Acked-by: Serge Hallyn <serge.hallyn@...onical.com>
---
 fs/inode.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/inode.c b/fs/inode.c
index 69b8b526c194..cd52170f9117 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1690,7 +1690,8 @@ int should_remove_suid(struct dentry *dentry)
 	if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
 		kill |= ATTR_KILL_SGID;
 
-	if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
+	if (unlikely(kill && !ns_capable(dentry->d_sb->s_user_ns, CAP_FSETID) &&
+		     S_ISREG(mode)))
 		return kill;
 
 	return 0;
-- 
2.7.4