linux-kernel - [REVIEW][PATCH 6/6] fs: Allow CAP_SYS_ADMIN in s_user

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Message-Id: <20180523232538.4880-6-ebiederm@xmission.com>
Date:   Wed, 23 May 2018 18:25:38 -0500
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     Linux Containers <containers@...ts.linux-foundation.org>
Cc:     linux-fsdevel@...r.kernel.org,
        Seth Forshee <seth.forshee@...onical.com>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Christian Brauner <christian@...uner.io>,
        linux-kernel@...r.kernel.org,
        "Eric W . Biederman" <ebiederm@...ssion.com>
Subject: [REVIEW][PATCH 6/6] fs: Allow CAP_SYS_ADMIN in s_user_ns to freeze and thaw filesystems

From: Seth Forshee <seth.forshee@...onical.com>

The user in control of a super block should be allowed to freeze
and thaw it. Relax the restrictions on the FIFREEZE and FITHAW
ioctls to require CAP_SYS_ADMIN in s_user_ns.

Signed-off-by: Seth Forshee <seth.forshee@...onical.com>
Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---
 fs/ioctl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 4823431d1c9d..b445b13fc59b 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -549,7 +549,7 @@ static int ioctl_fsfreeze(struct file *filp)
 {
 	struct super_block *sb = file_inode(filp)->i_sb;
 
-	if (!capable(CAP_SYS_ADMIN))
+	if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
 		return -EPERM;
 
 	/* If filesystem doesn't support freeze feature, return. */
@@ -566,7 +566,7 @@ static int ioctl_fsthaw(struct file *filp)
 {
 	struct super_block *sb = file_inode(filp)->i_sb;
 
-	if (!capable(CAP_SYS_ADMIN))
+	if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
 		return -EPERM;
 
 	/* Thaw */
-- 
2.14.1