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Re: [PATCH v4 1/3] virtiofsd: extract lo_do_open() from lo_open()
From: |
Greg Kurz |
Subject: |
Re: [PATCH v4 1/3] virtiofsd: extract lo_do_open() from lo_open() |
Date: |
Wed, 3 Feb 2021 16:45:10 +0100 |
On Wed, 3 Feb 2021 14:47:30 +0000
"Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:
> * Greg Kurz (groug@kaod.org) wrote:
> > On Wed, 3 Feb 2021 11:37:17 +0000
> > Stefan Hajnoczi <stefanha@redhat.com> wrote:
> >
> > > Both lo_open() and lo_create() have similar code to open a file. Extract
> > > a common lo_do_open() function from lo_open() that will be used by
> > > lo_create() in a later commit.
> > >
> > > Since lo_do_open() does not otherwise need fuse_req_t req, convert
> > > lo_add_fd_mapping() to use struct lo_data *lo instead.
> > >
> > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> > > ---
> >
> > With the s/ENOMEM/-ENOMEM/ change in lo_do_open() suggested by patchew,
>
> Isn't it actually the return -errno that's different from the original?
>
Yes and this is expected. The original sits in the top level handler
lo_open() which sends the reply back to the client and doesn't have
a return value, while lo_do_open() has a return value which should be
0 or negative.
> Dave
>
> > Reviewed-by: Greg Kurz <groug@kaod.org>
> >
> > > tools/virtiofsd/passthrough_ll.c | 73 ++++++++++++++++++++------------
> > > 1 file changed, 46 insertions(+), 27 deletions(-)
> > >
> > > diff --git a/tools/virtiofsd/passthrough_ll.c
> > > b/tools/virtiofsd/passthrough_ll.c
> > > index 5fb36d9407..e63cbd3fb7 100644
> > > --- a/tools/virtiofsd/passthrough_ll.c
> > > +++ b/tools/virtiofsd/passthrough_ll.c
> > > @@ -459,17 +459,17 @@ static void lo_map_remove(struct lo_map *map,
> > > size_t key)
> > > }
> > >
> > > /* Assumes lo->mutex is held */
> > > -static ssize_t lo_add_fd_mapping(fuse_req_t req, int fd)
> > > +static ssize_t lo_add_fd_mapping(struct lo_data *lo, int fd)
> > > {
> > > struct lo_map_elem *elem;
> > >
> > > - elem = lo_map_alloc_elem(&lo_data(req)->fd_map);
> > > + elem = lo_map_alloc_elem(&lo->fd_map);
> > > if (!elem) {
> > > return -1;
> > > }
> > >
> > > elem->fd = fd;
> > > - return elem - lo_data(req)->fd_map.elems;
> > > + return elem - lo->fd_map.elems;
> > > }
> > >
> > > /* Assumes lo->mutex is held */
> > > @@ -1651,6 +1651,38 @@ static void update_open_flags(int writeback, int
> > > allow_direct_io,
> > > }
> > > }
> > >
> > > +static int lo_do_open(struct lo_data *lo, struct lo_inode *inode,
> > > + struct fuse_file_info *fi)
> > > +{
> > > + char buf[64];
> > > + ssize_t fh;
> > > + int fd;
> > > +
> > > + update_open_flags(lo->writeback, lo->allow_direct_io, fi);
> > > +
> > > + sprintf(buf, "%i", inode->fd);
> > > + fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
> > > + if (fd == -1) {
> > > + return -errno;
> > > + }
> > > +
> > > + pthread_mutex_lock(&lo->mutex);
> > > + fh = lo_add_fd_mapping(lo, fd);
> > > + pthread_mutex_unlock(&lo->mutex);
> > > + if (fh == -1) {
> > > + close(fd);
> > > + return ENOMEM;
> > > + }
> > > +
> > > + fi->fh = fh;
> > > + if (lo->cache == CACHE_NONE) {
> > > + fi->direct_io = 1;
> > > + } else if (lo->cache == CACHE_ALWAYS) {
> > > + fi->keep_cache = 1;
> > > + }
> > > + return 0;
> > > +}
> > > +
> > > static void lo_create(fuse_req_t req, fuse_ino_t parent, const char
> > > *name,
> > > mode_t mode, struct fuse_file_info *fi)
> > > {
> > > @@ -1691,7 +1723,7 @@ static void lo_create(fuse_req_t req, fuse_ino_t
> > > parent, const char *name,
> > > ssize_t fh;
> > >
> > > pthread_mutex_lock(&lo->mutex);
> > > - fh = lo_add_fd_mapping(req, fd);
> > > + fh = lo_add_fd_mapping(lo, fd);
> > > pthread_mutex_unlock(&lo->mutex);
> > > if (fh == -1) {
> > > close(fd);
> > > @@ -1892,38 +1924,25 @@ static void lo_fsyncdir(fuse_req_t req,
> > > fuse_ino_t ino, int datasync,
> > >
> > > static void lo_open(fuse_req_t req, fuse_ino_t ino, struct
> > > fuse_file_info *fi)
> > > {
> > > - int fd;
> > > - ssize_t fh;
> > > - char buf[64];
> > > struct lo_data *lo = lo_data(req);
> > > + struct lo_inode *inode = lo_inode(req, ino);
> > > + int err;
> > >
> > > fuse_log(FUSE_LOG_DEBUG, "lo_open(ino=%" PRIu64 ", flags=%d)\n", ino,
> > > fi->flags);
> > >
> > > - update_open_flags(lo->writeback, lo->allow_direct_io, fi);
> > > -
> > > - sprintf(buf, "%i", lo_fd(req, ino));
> > > - fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
> > > - if (fd == -1) {
> > > - return (void)fuse_reply_err(req, errno);
> > > - }
> > > -
> > > - pthread_mutex_lock(&lo->mutex);
> > > - fh = lo_add_fd_mapping(req, fd);
> > > - pthread_mutex_unlock(&lo->mutex);
> > > - if (fh == -1) {
> > > - close(fd);
> > > - fuse_reply_err(req, ENOMEM);
> > > + if (!inode) {
> > > + fuse_reply_err(req, EBADF);
> > > return;
> > > }
> > >
> > > - fi->fh = fh;
> > > - if (lo->cache == CACHE_NONE) {
> > > - fi->direct_io = 1;
> > > - } else if (lo->cache == CACHE_ALWAYS) {
> > > - fi->keep_cache = 1;
> > > + err = lo_do_open(lo, inode, fi);
> > > + lo_inode_put(lo, &inode);
> > > + if (err) {
> > > + fuse_reply_err(req, err);
> > > + } else {
> > > + fuse_reply_open(req, fi);
> > > }
> > > - fuse_reply_open(req, fi);
> > > }
> > >
> > > static void lo_release(fuse_req_t req, fuse_ino_t ino,
> >
[PATCH v4 2/3] virtiofsd: optionally return inode pointer from lo_do_lookup(), Stefan Hajnoczi, 2021/02/03
[PATCH v4 3/3] virtiofsd: prevent opening of special files (CVE-2020-35517), Stefan Hajnoczi, 2021/02/03