On 08/26/2016 10:07 AM, Greg Kurz wrote: > According to the 9P spec http://man.cat-v.org/plan_9/5/open about the > create request: > > The names . and .. are special; it is illegal to create files with these > names. > > This patch causes the create and lcreate requests to fail with EINVAL if > the file name is either "." or "..". > > Even if it isn't explicitly written in the spec, this patch extends the > checking to all requests that may cause a filename to be created: > > - mknod > - rename > - renameat > - mkdir > - link > - symlink > > The unlinkat request also gets patched for consistency (even if > rmdir("foo/..") is expected to fail according to POSIX.1-2001). > > The various error values come from the linux manual pages.
Linux doesn't always obey the POSIX rules for which errno to use, but I
think your choices here are mostly okay.
>
> Suggested-by: Peter Maydell <peter.mayd...@linaro.org>
> Signed-off-by: Greg Kurz <gr...@kaod.org>
> ---
> hw/9pfs/9p.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 51 insertions(+)
>
> @@ -2545,6 +2575,11 @@ static void v9fs_rename(void *opaque)
> goto out_nofid;
> }
>
> + if (!strcmp(".", name.data) || !strcmp("..", name.data)) {
> + err = -EBUSY;
> + goto out_nofid;
> + }
POSIX suggests that EISDIR is better than EBUSY here.
> +
> fidp = get_fid(pdu, fid);
> if (fidp == NULL) {
> err = -ENOENT;
> @@ -2662,6 +2697,12 @@ static void v9fs_renameat(void *opaque)
> goto out_err;
> }
>
> + if (!strcmp(".", old_name.data) || !strcmp("..", old_name.data) ||
> + !strcmp(".", new_name.data) || !strcmp("..", new_name.data)) {
> + err = -EBUSY;
Ditto.
Wait. Why is v9fs_rename() only checking one name, but v9fs_renameat()
checking both old_name and new_name? Also, should link be checking both
the source and destination name?
> @@ -3033,6 +3079,11 @@ static void v9fs_mkdir(void *opaque)
> goto out_nofid;
> }
>
> + if (!strcmp(".", name.data) || !strcmp("..", name.data)) {
> + err = -EEXIST;
> + goto out_nofid;
> + }
> +
Unrelated to this patch, but why do we have v9fs_renameat but not
v9fs_mkdirat?
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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