linux-kernel - [PATCH 26/34] union-mount: Temporarily disable some syscalls

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Message-Id: <1284675145-4391-27-git-send-email-vaurora@redhat.com>
Date:	Thu, 16 Sep 2010 15:12:17 -0700
From:	Valerie Aurora <vaurora@...hat.com>
To:	Alexander Viro <viro@...iv.linux.org.uk>
Cc:	Miklos Szeredi <miklos@...redi.hu>,
	Christoph Hellwig <hch@...radead.org>,
	Andreas Gruenbacher <agruen@...e.de>,
	Nick Piggin <npiggin@...nel.dk>, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, Valerie Aurora <vaurora@...hat.com>
Subject: [PATCH 26/34] union-mount: Temporarily disable some syscalls

After some of the following patches in this series, a few system calls
will crash the kernel if called on union-mounted file systems.
Temporarily disable rename(), unlink(), and rmdir() on unioned file
systems until they are correctly implemented by later patches.

Signed-off-by: Valerie Aurora <vaurora@...hat.com>
---
 fs/namei.c |   17 +++++++++++++++++
 1 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 0b6378e..2de4378 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -35,6 +35,7 @@
 #include <asm/uaccess.h>
 
 #include "internal.h"
+#include "union.h"
 
 /* [Feb-1997 T. Schoebel-Theuer]
  * Fundamental changes in the pathname lookup mechanisms (namei)
@@ -2404,6 +2405,11 @@ static long do_rmdir(int dfd, const char __user *pathname)
 	if (error)
 		return error;
 
+	/* rmdir() on union mounts not implemented yet */
+	error = -EINVAL;
+	if (IS_DIR_UNIONED(nd.path.dentry))
+		goto exit1;
+
 	switch(nd.last_type) {
 	case LAST_DOTDOT:
 		error = -ENOTEMPTY;
@@ -2500,6 +2506,11 @@ static long do_unlinkat(int dfd, const char __user *pathname)
 	if (nd.last_type != LAST_NORM)
 		goto exit1;
 
+	/* unlink() on union mounts not implemented yet */
+	error = -EINVAL;
+	if (IS_DIR_UNIONED(nd.path.dentry))
+		goto exit1;
+
 	nd.flags &= ~LOOKUP_PARENT;
 
 	mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
@@ -2890,6 +2901,12 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
 	if (oldnd.path.mnt != newnd.path.mnt)
 		goto exit2;
 
+	/* rename() on union mounts not implemented yet */
+	error = -EXDEV;
+	if (IS_DIR_UNIONED(oldnd.path.dentry) ||
+	    IS_DIR_UNIONED(newnd.path.dentry))
+		goto exit2;
+
 	old_dir = oldnd.path.dentry;
 	error = -EBUSY;
 	if (oldnd.last_type != LAST_NORM)
-- 
1.6.3.3

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