Re: [PATCH 08/29] tools/xenlogd: add 9pfs walk request support

[Juergen Gross <jgross@xxxxxxxx>]

On 03.11.23 20:48, Jason Andryuk wrote:
> On Wed, Nov 1, 2023 at 6:09 AM Juergen Gross <jgross@xxxxxxxx> wrote:
> > Add the walk request of the 9pfs protocol.
> >
> > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > ---
> >   tools/xenlogd/io.c      | 138 ++++++++++++++++++++++++++++++++++++++++
> >   tools/xenlogd/xenlogd.h |   1 +
> >   2 files changed, 139 insertions(+)
> >
> > diff --git a/tools/xenlogd/io.c b/tools/xenlogd/io.c
> > index fa825c9f39..778e1dc2c9 100644
> > --- a/tools/xenlogd/io.c
> > +++ b/tools/xenlogd/io.c
> > @@ -600,6 +616,124 @@ static void p9_attach(device *device, struct p9_header 
> > *hdr)
> >       fill_buffer(device, hdr->cmd + 1, hdr->tag, "Q", &qid);
> >   }
> >
> > +static void p9_walk(device *device, struct p9_header *hdr)
> > +{
> > +    uint32_t fid;
> > +    uint32_t newfid;
> > +    struct p9_fid *fidp;
> > +    struct p9_qid *qids = NULL;
> > +    unsigned int n_names = 0;
> > +    unsigned int *names = NULL;
> > +    unsigned int walked = 0;
> > +    unsigned int i;
> > +    char *path = NULL;
> > +    unsigned int path_len;
> > +    int ret;
> > +
> > +    ret = fill_data(device, "UUaS", &fid, &newfid, &n_names, &names);
> > +    if ( n_names > P9_WALK_MAXELEM )
> > +    {
> > +        p9_error(device, hdr->tag, EINVAL);
> > +        goto out;
> > +    }
> > +    if ( ret != 3 + n_names )
> > +    {
> > +        p9_error(device, hdr->tag, errno);
> > +        goto out;
> > +    }
> > +
> > +    fidp = find_fid(device, fid);
> > +    if ( !fidp )
> > +    {
> > +        p9_error(device, hdr->tag, ENOENT);
> > +        goto out;
> > +    }
> > +    if ( fidp->opened )
> > +    {
> > +        p9_error(device, hdr->tag, EINVAL);
> > +        goto out;
> > +    }
> https://ericvh.github.io/9p-rfc/rfc9p2000.html#anchor33
> """
> The fid must represent a directory unless zero path name elements are specified.
> """
> and
> """
> For the first elementwise walk to succeed, the file identified by fid
> must be a directory, and the implied user of the request must have
> permission to search the directory (see intro(5)). Subsequent
> elementwise walks have equivalent restrictions applied to the implicit
> fid that results from the preceding elementwise walk.
> """
>
> Maybe a dir check should be added?  However, it doesn't look like QEMU
> does this check.  Seems like it is implicitly checked by the path
> concatenation, so it may be fine as-is.
>
> If you think it's ok as-is:
> Reviewed-by: Jason Andryuk <jandryuk@xxxxxxxxx>
Thanks.

I think I'll leave it as is.


Juergen

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