linux-kernel - [PATCH] fs/sync.c : Add CAP_SYS

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Date:	Thu, 16 Apr 2015 19:43:34 +0800
From:	Wuqixuan <wuqixuan@...wei.com>
To:	<viro@...iv.linux.org.uk>, <linux-fsdevel@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH] fs/sync.c : Add CAP_SYS_ADMIN checking before sync

The process, supposed in one container, can't flush the metadata
and data of the all host's partitions without CAP_SYS_ADMIN
capability, like sys_mount is doing. The checking will prevent some
vicious programs impacting IO sequnces of those partitions,
particularly, the ones which can't be accessed in the container.

Signed-off-by: Last Wu <wuqixuan@...wei.com>
---
fs/sync.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/fs/sync.c b/fs/sync.c
index fbc98ee..9f07909 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -103,6 +103,9 @@ SYSCALL_DEFINE0(sync)
{
int nowait = 0, wait = 1;

+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
wakeup_flusher_threads(0, WB_REASON_SYNC);
iterate_supers(sync_inodes_one_sb, NULL);
iterate_supers(sync_fs_one_sb, &nowait);
--
1.9.1


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