[PATCH 07/11] fs: Allow CAP_SYS_ADMIN in s_user_ns to freeze and thaw filesystems

[Dongsu Park]

From: Seth Forshee <seth.forshee at canonical.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.

Cc: linux-fsdevel at vger.kernel.org
Cc: linux-kernel at vger.kernel.org
Cc: Alexander Viro <viro at zeniv.linux.org.uk>
Signed-off-by: Seth Forshee <seth.forshee at canonical.com>
Signed-off-by: Dongsu Park <dongsu at kinvolk.io>
---
 fs/ioctl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 5ace7efb..8c628a8d 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 */
-- 
2.13.6