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| author | Miklos Szeredi <miklos@szeredi.hu> | 2015-12-11 16:30:49 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-02-25 12:01:24 -0800 |
| commit | 8373f6590f6b371bff2c5f2c0581548eb0192014 (patch) | |
| tree | f2d9f8ef550d2d58b8624a889d63e05f02be032b | |
| parent | 7193e802960f884e0ae6c40711c4e3c70fa3b070 (diff) | |
| download | lwn-8373f6590f6b371bff2c5f2c0581548eb0192014.tar.gz lwn-8373f6590f6b371bff2c5f2c0581548eb0192014.zip | |
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>
| -rw-r--r-- | fs/overlayfs/inode.c | 13 | ||||
| -rw-r--r-- | fs/overlayfs/super.c | 2 |
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"); |