@@ -61,6 +61,14 @@ int local_opendir_nofollow(FsContext *fs_ctx, const char *path)
return local_open_nofollow(fs_ctx, path, O_DIRECTORY | O_RDONLY, 0);
}
+static void renameat_preserve_errno(int odirfd, const char *opath, int ndirfd,
+ const char *npath)
+{
+ int serrno = errno;
+ renameat(odirfd, opath, ndirfd, npath);
+ errno = serrno;
+}
+
#define VIRTFS_META_DIR ".virtfs_metadata"
static char *local_mapped_attr_path(FsContext *ctx, const char *path)
@@ -1181,17 +1189,64 @@ static int local_renameat(FsContext *ctx, V9fsPath *olddir,
const char *new_name)
{
int ret;
- V9fsString old_full_name, new_full_name;
+ int odirfd, ndirfd;
+
+ odirfd = local_opendir_nofollow(ctx, olddir->data);
+ if (odirfd == -1) {
+ return -1;
+ }
+
+ ndirfd = local_opendir_nofollow(ctx, newdir->data);
+ if (ndirfd == -1) {
+ close_preserve_errno(odirfd);
+ return -1;
+ }
+
+ ret = renameat(odirfd, old_name, ndirfd, new_name);
+ if (ret < 0) {
+ goto out;
+ }
- v9fs_string_init(&old_full_name);
- v9fs_string_init(&new_full_name);
+ if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
+ int omap_dirfd, nmap_dirfd;
- v9fs_string_sprintf(&old_full_name, "%s/%s", olddir->data, old_name);
- v9fs_string_sprintf(&new_full_name, "%s/%s", newdir->data, new_name);
+ ret = mkdirat(ndirfd, VIRTFS_META_DIR, 0700);
+ if (ret < 0 && errno != EEXIST) {
+ goto err_undo_rename;
+ }
- ret = local_rename(ctx, old_full_name.data, new_full_name.data);
- v9fs_string_free(&old_full_name);
- v9fs_string_free(&new_full_name);
+ omap_dirfd = openat(odirfd, VIRTFS_META_DIR,
+ O_RDONLY | O_DIRECTORY | O_NOFOLLOW);
+ if (omap_dirfd == -1) {
+ goto err;
+ }
+
+ nmap_dirfd = openat(ndirfd, VIRTFS_META_DIR,
+ O_RDONLY | O_DIRECTORY | O_NOFOLLOW);
+ if (nmap_dirfd == -1) {
+ close_preserve_errno(omap_dirfd);
+ goto err;
+ }
+
+ /* rename the .virtfs_metadata files */
+ ret = renameat(omap_dirfd, old_name, nmap_dirfd, new_name);
+ close_preserve_errno(nmap_dirfd);
+ close_preserve_errno(omap_dirfd);
+ if (ret < 0 && errno != ENOENT) {
+ goto err_undo_rename;
+ }
+
+ ret = 0;
+ }
+ goto out;
+
+err:
+ ret = -1;
+err_undo_rename:
+ renameat_preserve_errno(ndirfd, new_name, odirfd, old_name);
+out:
+ close_preserve_errno(ndirfd);
+ close_preserve_errno(odirfd);
return ret;
}
The local_renameat() callback is currently a wrapper around local_rename() which is vulnerable to symlink attacks. This patch rewrites local_renameat() to have its own implementation, based on local_opendir_nofollow() and renameat(). This partly fixes CVE-2016-9602. Signed-off-by: Greg Kurz <groug@kaod.org> --- hw/9pfs/9p-local.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 63 insertions(+), 8 deletions(-)