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[PATCH v8 3/7] xfs: ioctl check for capabilities in the current user nam

To: xfs@xxxxxxxxxxx
Subject: [PATCH v8 3/7] xfs: ioctl check for capabilities in the current user namespace
From: Dwight Engen <dwight.engen@xxxxxxxxxx>
Date: Thu, 15 Aug 2013 14:08:00 -0400
Cc: Ben Myers <bpm@xxxxxxx>, Dave Chinner <david@xxxxxxxxxxxxx>, Dwight Engen <dwight.engen@xxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1376590084-12888-1-git-send-email-dwight.engen@xxxxxxxxxx>
References: <1376590084-12888-1-git-send-email-dwight.engen@xxxxxxxxxx>
Use inode_capable() to check if SUID|SGID bits should be cleared to match
similar check in inode_change_ok().

The check for CAP_LINUX_IMMUTABLE was not modified since all other file
systems also check against init_user_ns rather than current_user_ns.

Only allow changing of projid from init_user_ns.

Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Gao feng <gaofeng@xxxxxxxxxxxxxx>
Signed-off-by: Dwight Engen <dwight.engen@xxxxxxxxxx>
---
 fs/xfs/xfs_ioctl.c  | 11 +++++++++--
 kernel/capability.c |  1 +
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index e9c17e2..999c1ef 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1015,15 +1015,22 @@ xfs_ioctl_setattr(
         * to the file owner ID, except in cases where the
         * CAP_FSETID capability is applicable.
         */
-       if (current_fsuid() != ip->i_d.di_uid && !capable(CAP_FOWNER)) {
+       if (!inode_owner_or_capable(VFS_I(ip))) {
                code = XFS_ERROR(EPERM);
                goto error_return;
        }
 
        /*
         * Do a quota reservation only if projid is actually going to change.
+        * Only allow changing of projid from init_user_ns since it is a
+        * non user namespace aware identifier.
         */
        if (mask & FSX_PROJID) {
+               if (current_user_ns() != &init_user_ns) {
+                       code = XFS_ERROR(EINVAL);
+                       goto error_return;
+               }
+
                if (XFS_IS_QUOTA_RUNNING(mp) &&
                    XFS_IS_PQUOTA_ON(mp) &&
                    xfs_get_projid(ip) != fa->fsx_projid) {
@@ -1137,7 +1144,7 @@ xfs_ioctl_setattr(
                 * cleared upon successful return from chown()
                 */
                if ((ip->i_d.di_mode & (S_ISUID|S_ISGID)) &&
-                   !capable(CAP_FSETID))
+                   !inode_capable(VFS_I(ip), CAP_FSETID))
                        ip->i_d.di_mode &= ~(S_ISUID|S_ISGID);
 
                /*
diff --git a/kernel/capability.c b/kernel/capability.c
index f6c2ce5..a4b6744 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -464,3 +464,4 @@ bool inode_capable(const struct inode *inode, int cap)
 
        return ns_capable(ns, cap) && kuid_has_mapping(ns, inode->i_uid);
 }
+EXPORT_SYMBOL(inode_capable);
-- 
1.8.1.4

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