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virtiofsd: validate path components 

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 <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
master
Stefan Hajnoczi 2019-02-26 17:58:59 +00:00 committed by Dr. David Alan Gilbert
parent 5fe319a7b1
commit 25dae28c58
1 changed files with 53 additions and 6 deletions
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59
tools/virtiofsd/passthrough_ll.c
View File

@ -133,6 +133,21 @@ 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)
{
@ -681,6 +696,15 @@ static void lo_lookup(fuse_req_t req, fuse_ino_t parent, const char *name)
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);
@ -762,6 +786,11 @@ 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);
@ -863,6 +892,11 @@ 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);
@ -904,6 +938,10 @@ 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);
@ -916,6 +954,11 @@ 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;
@ -930,6 +973,11 @@ 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);
@ -1093,12 +1141,6 @@ 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)
{
@ -1248,6 +1290,11 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
parent, name);
}
if (!is_safe_path_component(name)) {
fuse_reply_err(req, EINVAL);
return;
}
err = lo_change_cred(req, &old);
if (err) {
goto out;