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authorMiklos Szeredi <miklos@szeredi.hu>2015-12-11 16:30:49 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-02-25 12:01:24 -0800
commit8373f6590f6b371bff2c5f2c0581548eb0192014 (patch)
treef2d9f8ef550d2d58b8624a889d63e05f02be032b /fs/overlayfs
parent7193e802960f884e0ae6c40711c4e3c70fa3b070 (diff)
ovl: setattr: check permissions before copy-up
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@szeredi.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/overlayfs')
-rw-r--r--fs/overlayfs/inode.c13
-rw-r--r--fs/overlayfs/super.c2
2 files changed, 15 insertions, 0 deletions
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 4060ffde8722..b29036aa8d7c 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -42,6 +42,19 @@ 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 ff826652feae..f42c9407fbad 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>
@@ -910,6 +911,7 @@ 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");