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SubjectRe: [PATCH 2/4] autofs4 - track uid and gid of last mount requester
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On Fri, 2008-08-08 at 11:25 +0800, Ian Kent wrote:
> On Thu, 2008-08-07 at 13:46 -0700, Andrew Morton wrote:
> > On Thu, 07 Aug 2008 19:40:14 +0800
> > Ian Kent <raven@themaw.net> wrote:
> >
> > > Patch to track the uid and gid of the last process to request a mount
> > > for on an autofs dentry.
> >
> > pet peeve: changelog should not tell the reader that this is a "patch".
> > Because when someone is reading the changelog in the git repository,
> > they hopefully already know that.
> >
> > > Signed-off-by: Ian Kent <raven@themaw.net>
> > >
> > > ---
> > >
> > > fs/autofs4/autofs_i.h | 3 +++
> > > fs/autofs4/inode.c | 2 ++
> > > fs/autofs4/waitq.c | 34 ++++++++++++++++++++++++++++++++++
> > > 3 files changed, 39 insertions(+), 0 deletions(-)
> > >
> > >
> > > diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
> > > index ea024d8..fa76d18 100644
> > > --- a/fs/autofs4/autofs_i.h
> > > +++ b/fs/autofs4/autofs_i.h
> > > @@ -63,6 +63,9 @@ struct autofs_info {
> > > unsigned long last_used;
> > > atomic_t count;
> > >
> > > + uid_t uid;
> > > + gid_t gid;
> > > +
> > > mode_t mode;
> > > size_t size;
> > >
> > > diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
> > > index 9ca2d07..9408507 100644
> > > --- a/fs/autofs4/inode.c
> > > +++ b/fs/autofs4/inode.c
> > > @@ -53,6 +53,8 @@ struct autofs_info *autofs4_init_ino(struct autofs_info *ino,
> > > atomic_set(&ino->count, 0);
> > > }
> > >
> > > + ino->uid = 0;
> > > + ino->gid = 0;
> > > ino->mode = mode;
> > > ino->last_used = jiffies;
> > >
> > > diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
> > > index 6d87bb1..7c60c0b 100644
> > > --- a/fs/autofs4/waitq.c
> > > +++ b/fs/autofs4/waitq.c
> > > @@ -457,6 +457,40 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
> > >
> > > status = wq->status;
> > >
> > > + /*
> > > + * For direct and offset mounts we need to track the requestrer
> >
> > typo which I'll fix.
> >
> > > + * uid and gid in the dentry info struct. This is so it can be
> > > + * supplied, on request, by the misc device ioctl interface.
> > > + * This is needed during daemon resatart when reconnecting
> > > + * to existing, active, autofs mounts. The uid and gid (and
> > > + * related string values) may be used for macro substitution
> > > + * in autofs mount maps.
> > > + */
> > > + if (!status) {
> > > + struct autofs_info *ino;
> > > + struct dentry *de = NULL;
> > > +
> > > + /* direct mount or browsable map */
> > > + ino = autofs4_dentry_ino(dentry);
> > > + if (!ino) {
> > > + /* If not lookup actual dentry used */
> > > + de = d_lookup(dentry->d_parent, &dentry->d_name);
> > > + if (de)
> > > + ino = autofs4_dentry_ino(de);
> > > + }
> > > +
> > > + /* Set mount requester */
> > > + if (ino) {
> > > + spin_lock(&sbi->fs_lock);
> > > + ino->uid = wq->uid;
> > > + ino->gid = wq->gid;
> > > + spin_unlock(&sbi->fs_lock);
> > > + }
> > > +
> > > + if (de)
> > > + dput(de);
> > > + }
> > > +
> >
> > Please remind me again why autofs's use of current->uid and
> > current->gid is not busted in the presence of PID namespaces, where
> > these things are no longer system-wide unique?
>
> We didn't really get to the bottom of that last time I posted this but
> hopefully Serge will get right on this and we can sort out what, idf
> anything I need to do.

But, at this stage, I believe that if namespaces are being used then
there would also need to be a daemon within the container which would
have the same namespace view as other processes in the container. I
expect that the situation is not nearly as straight forward as I think
so I'll need to wait for further comments.

Ian




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