[added to the 4.1 stable tree] ovl: setattr: check permissions before copy-up
From: Sasha Levin <hidden>
Date: 2016-02-10 15:12:39
Subsystem:
filesystems (vfs and infrastructure), overlay filesystem, the rest · Maintainers:
Alexander Viro, Christian Brauner, Miklos Szeredi, Amir Goldstein, Linus Torvalds
From: Miklos Szeredi <miklos@szeredi.hu> This patch has been added to the 4.1 stable tree. If you have any objections, please let us know. =============== [ Upstream commit cf9a6784f7c1b5ee2b9159a1246e327c331c5697 ] 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@szeredi.hu> Cc: <redacted> Signed-off-by: Sasha Levin <redacted> --- fs/overlayfs/inode.c | 13 +++++++++++++ fs/overlayfs/super.c | 2 ++ 2 files changed, 15 insertions(+)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index ba0db26..a1b069e 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c@@ -45,6 +45,19 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr) 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;
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index c4b595e..bd6d5c1 100644
--- 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>
@@ -847,6 +848,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) } 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");
--
2.5.0