On 02/27/2017 04:59 PM, Greg Kurz wrote: > When using the passthrough security mode, symbolic links created by the > guest are actual symbolic links on the host file system. >
Hmm, I just barely started reviewing the series, and see a pull request.
At this point, anything I point out can probably be done as followup
patches rather than forcing a respin of the pull (and soft freeze is
appropriate for that).
> Suggested-by: Jann Horn <ja...@google.com>
> Signed-off-by: Greg Kurz <gr...@kaod.org>
> Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
> (renamed openat_nofollow() to relative_openat_nofollow(),
> assert path is relative, Greg Kurz)
> Signed-off-by: Greg Kurz <gr...@kaod.org>
> ---
> +int relative_openat_nofollow(int dirfd, const char *path, int flags,
> + mode_t mode)
> +{
> + int fd;
> +
> + assert(path[0] != '/');
If you move this assert...
> +
> + fd = dup(dirfd);
> + if (fd == -1) {
> + return -1;
> + }
> +
> + while (*path) {
> + const char *c;
> + int next_fd;
> + char *head;
...here, you can make sure there are no 'a//b' issues to worry about.
> +
> + head = g_strdup(path);
> + c = strchr(path, '/');
> + if (c) {
> + head[c - path] = 0;
> + next_fd = openat_dir(fd, head);
> + } else {
> + next_fd = openat_file(fd, head, flags, mode);
> + }
> + g_free(head);
> + if (next_fd == -1) {
> + close_preserve_errno(fd);
> + return -1;
> + }
> + close(fd);
> + fd = next_fd;
> +
> + if (!c) {
> + break;
> + }
> + path = c + 1;
or else add an assert here.
> +static inline int openat_file(int dirfd, const char *name, int flags,
> + mode_t mode)
> +{
> + int fd, serrno;
> +
> + fd = openat(dirfd, name, flags | O_NOFOLLOW | O_NOCTTY | O_NONBLOCK,
> + mode);
> + if (fd == -1) {
> + return -1;
> + }
> +
> + serrno = errno;
> + /* O_NONBLOCK was only needed to open the file. Let's drop it. */
> + assert(!fcntl(fd, F_SETFL, flags));
Ewww. Side effect inside an assert(). :(
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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