This fixes CVE-2016-9602 for the "passthrough" security model.
Signed-off-by: Greg Kurz <gr...@kaod.org>
---
hw/9pfs/9p-local.c | 128 ++++++++++++++++++++++++----------------------------
1 file changed, 59 insertions(+), 69 deletions(-)
diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
index dbc56b16979c..48d46b6abd28 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -77,6 +77,13 @@ char *local_basename(const char *path)
return result;
}
+static void unlinkat_preserve_errno(int dirfd, const char *path, int flags)
+{
+ int serrno = errno;
+ unlinkat(dirfd, path, flags);
+ errno = serrno;
+}
+
#define VIRTFS_META_DIR ".virtfs_metadata"
static char *local_mapped_attr_path(FsContext *ctx, const char *path)
@@ -319,31 +326,41 @@ static int local_set_xattr(const char *path, FsCred
*credp)
return 0;
}
-static int local_post_create_passthrough(FsContext *fs_ctx, const char *path,
- FsCred *credp)
+static int local_post_create_passthrough(FsContext *fs_ctx, int dirfd,
+ const char *name, FsCred *credp)
{
- char *buffer;
+ int fd, err = -1;
- buffer = rpath(fs_ctx, path);
- if (lchown(buffer, credp->fc_uid, credp->fc_gid) < 0) {
+ if (fchownat(dirfd, name, credp->fc_uid, credp->fc_gid,
+ AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH) < 0) {
/*
* If we fail to change ownership and if we are
* using security model none. Ignore the error
*/
if ((fs_ctx->export_flags & V9FS_SEC_MASK) != V9FS_SM_NONE) {
- goto err;
+ return -1;
}
}
- if (chmod(buffer, credp->fc_mode & 07777) < 0) {
- goto err;
+ if (name[0]) {
+ fd = openat_nofollow(dirfd, name, O_RDONLY, 0);
+ if (fd == -1) {
+ return -1;
+ }
+ } else {
+ fd = dirfd;
}
- g_free(buffer);
- return 0;
-err:
- g_free(buffer);
- return -1;
+ if (fchmod(fd, credp->fc_mode & 07777) < 0) {
+ goto out;
+ }
+ err = 0;
+
+out:
+ if (name[0]) {
+ close_preserve_errno(fd);
+ }
+ return err;
}
static int readlink_nofollow(FsContext *fs_ctx, const char *path, char *buf,
@@ -637,34 +654,27 @@ out:
static int local_mknod_passthrough(FsContext *fs_ctx, V9fsPath *dir_path,
const char *name, FsCred *credp)
{
- char *path;
- int err = -1;
- int serrno = 0;
- V9fsString fullname;
- char *buffer = NULL;
+ int dirfd, err;
- v9fs_string_init(&fullname);
- v9fs_string_sprintf(&fullname, "%s/%s", dir_path->data, name);
- path = fullname.data;
+ dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
+ if (dirfd == -1) {
+ return -1;
+ }
- buffer = rpath(fs_ctx, path);
- err = mknod(buffer, credp->fc_mode, credp->fc_rdev);
+ err = mknodat(dirfd, name, credp->fc_mode, credp->fc_rdev);
if (err == -1) {
goto out;
}
- err = local_post_create_passthrough(fs_ctx, path, credp);
+ err = local_post_create_passthrough(fs_ctx, dirfd, name, credp);
if (err == -1) {
- serrno = errno;
goto err_end;
}
goto out;
err_end:
- remove(buffer);
- errno = serrno;
+ unlinkat_preserve_errno(dirfd, name, 0);
out:
- g_free(buffer);
- v9fs_string_free(&fullname);
+ close_preserve_errno(dirfd);
return err;
}
@@ -755,34 +765,27 @@ out:
static int local_mkdir_passthrough(FsContext *fs_ctx, V9fsPath *dir_path,
const char *name, FsCred *credp)
{
- char *path;
- int err = -1;
- int serrno = 0;
- V9fsString fullname;
- char *buffer = NULL;
+ int dirfd, err;
- v9fs_string_init(&fullname);
- v9fs_string_sprintf(&fullname, "%s/%s", dir_path->data, name);
- path = fullname.data;
+ dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
+ if (dirfd == -1) {
+ return -1;
+ }
- buffer = rpath(fs_ctx, path);
- err = mkdir(buffer, credp->fc_mode);
+ err = mkdirat(dirfd, name, credp->fc_mode);
if (err == -1) {
goto out;
}
- err = local_post_create_passthrough(fs_ctx, path, credp);
+ err = local_post_create_passthrough(fs_ctx, dirfd, name, credp);
if (err == -1) {
- serrno = errno;
goto err_end;
}
goto out;
err_end:
- remove(buffer);
- errno = serrno;
+ unlinkat_preserve_errno(dirfd, name, AT_REMOVEDIR);
out:
- g_free(buffer);
- v9fs_string_free(&fullname);
+ close_preserve_errno(dirfd);
return err;
}
@@ -939,44 +942,31 @@ static int local_open2_passthrough(FsContext *fs_ctx,
V9fsPath *dir_path,
const char *name, int flags, FsCred *credp,
V9fsFidOpenState *fs)
{
- char *path;
- int fd = -1;
int err = -1;
- int serrno = 0;
- V9fsString fullname;
- char *buffer = NULL;
+ int dirfd, fd;
- /*
- * Mark all the open to not follow symlinks
- */
- flags |= O_NOFOLLOW;
-
- v9fs_string_init(&fullname);
- v9fs_string_sprintf(&fullname, "%s/%s", dir_path->data, name);
- path = fullname.data;
+ dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
+ if (dirfd == -1) {
+ return -1;
+ }
- buffer = rpath(fs_ctx, path);
- fd = open(buffer, flags, credp->fc_mode);
+ fd = openat(dirfd, name, flags | O_NOFOLLOW, credp->fc_mode);
if (fd == -1) {
- err = fd;
goto out;
}
- err = local_post_create_passthrough(fs_ctx, path, credp);
+ err = local_post_create_passthrough(fs_ctx, fd, "", credp);
if (err == -1) {
- serrno = errno;
goto err_end;
}
- err = fd;
fs->fd = fd;
goto out;
err_end:
- close(fd);
- remove(buffer);
- errno = serrno;
+ unlinkat_preserve_errno(dirfd, name,
+ flags & O_DIRECTORY ? AT_REMOVEDIR : 0);
+ close_preserve_errno(fd);
out:
- g_free(buffer);
- v9fs_string_free(&fullname);
+ close_preserve_errno(dirfd);
return err;
}
