On Fri, 26 Aug 2016 13:49:00 -0500 Eric Blake <ebl...@redhat.com> wrote:
> 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. > Ok. > > + > > 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. > Ok. > 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? > v9fs_rename() and v9fs_link() only take a single name argument (see the "dds" mask passed to pdu_unmarshal()). > > @@ -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? > I don't know but I guess it is simply not implemented. FWIW the only reference I could find for 9P requests that are not documented in http://man.cat-v.org/plan_9/5/ is include/net/9p/9p.h in the linux kernel tree. The official linux client has P9_TRENAME, P9_TRENAMEAT and P9_TMKDIR, but no P9_TMKDIRAT...
pgpe4RHOvDudo.pgp
Description: OpenPGP digital signature
