This is a note to let you know that I've just added the patch titled
ovl: setattr: check permissions before copy-up
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ovl-setattr-check-permissions-before-copy-up.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From cf9a6784f7c1b5ee2b9159a1246e327c331c5697 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <miklos@xxxxxxxxxx>
Date: Fri, 11 Dec 2015 16:30:49 +0100
Subject: ovl: setattr: check permissions before copy-up
From: Miklos Szeredi <miklos@xxxxxxxxxx>
commit cf9a6784f7c1b5ee2b9159a1246e327c331c5697 upstream.
Without this copy-up of a file can be forced, even without actually being
allowed to do anything on the file.
[Arnd Bergmann] include <linux/pagemap.h> for PAGE_CACHE_SIZE (used by
MAX_LFS_FILESIZE definition).
Signed-off-by: Miklos Szeredi <miklos@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/overlayfs/inode.c | 13 +++++++++++++
fs/overlayfs/super.c | 2 ++
2 files changed, 15 insertions(+)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -42,6 +42,19 @@ int ovl_setattr(struct dentry *dentry, s
int err;
struct dentry *upperdentry;
+ /*
+ * Check for permissions before trying to copy-up. This is redundant
+ * since it will be rechecked later by ->setattr() on upper dentry. But
+ * without this, copy-up can be triggered by just about anybody.
+ *
+ * We don't initialize inode->size, which just means that
+ * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not
+ * check for a swapfile (which this won't be anyway).
+ */
+ err = inode_change_ok(dentry->d_inode, attr);
+ if (err)
+ return err;
+
err = ovl_want_write(dentry);
if (err)
goto out;
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -9,6 +9,7 @@
#include <linux/fs.h>
#include <linux/namei.h>
+#include <linux/pagemap.h>
#include <linux/xattr.h>
#include <linux/security.h>
#include <linux/mount.h>
@@ -910,6 +911,7 @@ static int ovl_fill_super(struct super_b
}
sb->s_stack_depth = 0;
+ sb->s_maxbytes = MAX_LFS_FILESIZE;
if (ufs->config.upperdir) {
if (!ufs->config.workdir) {
pr_err("overlayfs: missing 'workdir'\n");
Patches currently in stable-queue which might be from miklos@xxxxxxxxxx are
queue-4.4/ovl-allow-zero-size-xattr.patch
queue-4.4/ovl-root-copy-attr.patch
queue-4.4/ovl-check-dentry-positiveness-in-ovl_cleanup_whiteouts.patch
queue-4.4/ovl-setattr-check-permissions-before-copy-up.patch
queue-4.4/ovl-use-a-minimal-buffer-in-ovl_copy_xattr.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html