From: Stefan Hajnoczi <stefa...@redhat.com>
Several FUSE requests contain single path components. A correct FUSE
client sends well-formed path components but there is currently no input
validation in case something went wrong or the client is malicious.
Refuse ".", "..", and paths containing '/' when we expect a path
component.
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
contrib/virtiofsd/passthrough_ll.c | 59 +++++++++++++++++++++++++++---
1 file changed, 53 insertions(+), 6 deletions(-)
diff --git a/contrib/virtiofsd/passthrough_ll.c
b/contrib/virtiofsd/passthrough_ll.c
index 9f84419816..702fedc38a 100644
--- a/contrib/virtiofsd/passthrough_ll.c
+++ b/contrib/virtiofsd/passthrough_ll.c
@@ -146,6 +146,21 @@ static void unref_inode(struct lo_data *lo, struct
lo_inode *inode, uint64_t n);
static struct lo_inode *lo_find(struct lo_data *lo, struct stat *st);
+static int is_dot_or_dotdot(const char *name)
+{
+ return name[0] == '.' && (name[1] == '\0' ||
+ (name[1] == '.' && name[2] == '\0'));
+}
+
+/* Is `path` a single path component that is not "." or ".."? */
+static int is_safe_path_component(const char *path)
+{
+ if (strchr(path, '/')) {
+ return 0;
+ }
+
+ return !is_dot_or_dotdot(path);
+}
static struct lo_data *lo_data(fuse_req_t req)
{
@@ -657,6 +672,14 @@ static void lo_lookup(fuse_req_t req, fuse_ino_t parent,
const char *name)
fuse_log(FUSE_LOG_DEBUG, "lo_lookup(parent=%" PRIu64 ",
name=%s)\n",
parent, name);
+ /* Don't use is_safe_path_component(), allow "." and ".." for NFS export
+ * support.
+ */
+ if (strchr(name, '/')) {
+ fuse_reply_err(req, EINVAL);
+ return;
+ }
+
err = lo_do_lookup(req, parent, name, &e);
if (err)
fuse_reply_err(req, err);
@@ -719,6 +742,11 @@ static void lo_mknod_symlink(fuse_req_t req, fuse_ino_t
parent,
struct fuse_entry_param e;
struct lo_cred old = {};
+ if (!is_safe_path_component(name)) {
+ fuse_reply_err(req, EINVAL);
+ return;
+ }
+
dir = lo_inode(req, parent);
if (!dir) {
fuse_reply_err(req, EBADF);
@@ -815,6 +843,11 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino,
fuse_ino_t parent,
struct fuse_entry_param e;
int saverr;
+ if (!is_safe_path_component(name)) {
+ fuse_reply_err(req, EINVAL);
+ return;
+ }
+
inode = lo_inode(req, ino);
if (!inode) {
fuse_reply_err(req, EBADF);
@@ -854,6 +887,10 @@ out_err:
static void lo_rmdir(fuse_req_t req, fuse_ino_t parent, const char *name)
{
int res;
+ if (!is_safe_path_component(name)) {
+ fuse_reply_err(req, EINVAL);
+ return;
+ }
res = unlinkat(lo_fd(req, parent), name, AT_REMOVEDIR);
@@ -866,6 +903,12 @@ static void lo_rename(fuse_req_t req, fuse_ino_t parent,
const char *name,
{
int res;
+ if (!is_safe_path_component(name) ||
+ !is_safe_path_component(newname)) {
+ fuse_reply_err(req, EINVAL);
+ return;
+ }
+
if (flags) {
fuse_reply_err(req, EINVAL);
return;
@@ -881,6 +924,11 @@ static void lo_unlink(fuse_req_t req, fuse_ino_t parent,
const char *name)
{
int res;
+ if (!is_safe_path_component(name)) {
+ fuse_reply_err(req, EINVAL);
+ return;
+ }
+
res = unlinkat(lo_fd(req, parent), name, 0);
fuse_reply_err(req, res == -1 ? errno : 0);
@@ -1031,12 +1079,6 @@ out_err:
fuse_reply_err(req, error);
}
-static int is_dot_or_dotdot(const char *name)
-{
- return name[0] == '.' && (name[1] == '\0' ||
- (name[1] == '.' && name[2] == '\0'));
-}
-
static void lo_do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
off_t offset, struct fuse_file_info *fi, int plus)
{
@@ -1179,6 +1221,11 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent,
const char *name,
fuse_log(FUSE_LOG_DEBUG, "lo_create(parent=%" PRIu64 ",
name=%s)\n",
parent, name);
+ if (!is_safe_path_component(name)) {
+ fuse_reply_err(req, EINVAL);
+ return;
+ }
+
err = lo_change_cred(req, &old);
if (err)
goto out;
--
2.23.0
