From: Stefan Hajnoczi <stefa...@redhat.com>
Do not expose file descriptor numbers to clients. This prevents the
abuse of internal file descriptors (like stdin/stdout).
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
contrib/virtiofsd/passthrough_ll.c | 113 +++++++++++++++++++++++------
1 file changed, 92 insertions(+), 21 deletions(-)
diff --git a/contrib/virtiofsd/passthrough_ll.c
b/contrib/virtiofsd/passthrough_ll.c
index 9f82166079..a71fbff143 100644
--- a/contrib/virtiofsd/passthrough_ll.c
+++ b/contrib/virtiofsd/passthrough_ll.c
@@ -60,6 +60,7 @@ struct lo_map_elem {
union {
struct lo_inode *inode;
struct lo_dirp *dirp;
+ int fd;
ssize_t freelist;
};
bool in_use;
@@ -107,6 +108,7 @@ struct lo_data {
struct lo_inode root; /* protected by lo->mutex */
struct lo_map ino_map; /* protected by lo->mutex */
struct lo_map dirp_map; /* protected by lo->mutex */
+ struct lo_map fd_map; /* protected by lo->mutex */
};
static const struct fuse_opt lo_opts[] = {
@@ -241,6 +243,19 @@ static void lo_map_remove(struct lo_map *map, size_t key)
map->freelist = key;
}
+/* Assumes lo->mutex is held */
+static ssize_t lo_add_fd_mapping(fuse_req_t req, int fd)
+{
+ struct lo_map_elem *elem;
+
+ elem = lo_map_alloc_elem(&lo_data(req)->fd_map);
+ if (!elem)
+ return -1;
+
+ elem->fd = fd;
+ return elem - lo_data(req)->fd_map.elems;
+}
+
/* Assumes lo->mutex is held */
static ssize_t lo_add_dirp_mapping(fuse_req_t req, struct lo_dirp *dirp)
{
@@ -350,6 +365,21 @@ static int utimensat_empty_nofollow(struct lo_inode *inode,
return utimensat(AT_FDCWD, procname, tv, 0);
}
+static int lo_fi_fd(fuse_req_t req, struct fuse_file_info *fi)
+{
+ struct lo_data *lo = lo_data(req);
+ struct lo_map_elem *elem;
+
+ pthread_mutex_lock(&lo->mutex);
+ elem = lo_map_get(&lo->fd_map, fi->fh);
+ pthread_mutex_unlock(&lo->mutex);
+
+ if (!elem)
+ return -1;
+
+ return elem->fd;
+}
+
static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
int valid, struct fuse_file_info *fi)
{
@@ -358,6 +388,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino,
struct stat *attr,
struct lo_inode *inode;
int ifd;
int res;
+ int fd;
inode = lo_inode(req, ino);
if (!inode) {
@@ -367,9 +398,13 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino,
struct stat *attr,
ifd = inode->fd;
+ /* If fi->fh is invalid we'll report EBADF later */
+ if (fi)
+ fd = lo_fi_fd(req, fi);
+
if (valid & FUSE_SET_ATTR_MODE) {
if (fi) {
- res = fchmod(fi->fh, attr->st_mode);
+ res = fchmod(fd, attr->st_mode);
} else {
sprintf(procname, "/proc/self/fd/%i", ifd);
res = chmod(procname, attr->st_mode);
@@ -390,7 +425,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino,
struct stat *attr,
}
if (valid & FUSE_SET_ATTR_SIZE) {
if (fi) {
- res = ftruncate(fi->fh, attr->st_size);
+ res = ftruncate(fd, attr->st_size);
} else {
sprintf(procname, "/proc/self/fd/%i", ifd);
res = truncate(procname, attr->st_size);
@@ -417,7 +452,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino,
struct stat *attr,
tv[1] = attr->st_mtim;
if (fi)
- res = futimens(fi->fh, tv);
+ res = futimens(fd, tv);
else
res = utimensat_empty_nofollow(inode, tv);
if (res == -1)
@@ -1041,7 +1076,18 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent,
const char *name,
lo_restore_cred(&old);
if (!err) {
- fi->fh = fd;
+ ssize_t fh;
+
+ pthread_mutex_lock(&lo->mutex);
+ fh = lo_add_fd_mapping(req, fd);
+ pthread_mutex_unlock(&lo->mutex);
+ if (fh == -1) {
+ close(fd);
+ fuse_reply_err(req, ENOMEM);
+ return;
+ }
+
+ fi->fh = fh;
err = lo_do_lookup(req, parent, name, &e);
}
if (lo->cache == CACHE_NEVER)
@@ -1082,6 +1128,7 @@ static void lo_fsyncdir(fuse_req_t req, fuse_ino_t ino,
int datasync,
static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
{
int fd;
+ ssize_t fh;
char buf[64];
struct lo_data *lo = lo_data(req);
@@ -1110,7 +1157,16 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi)
if (fd == -1)
return (void) fuse_reply_err(req, errno);
- fi->fh = fd;
+ pthread_mutex_lock(&lo->mutex);
+ fh = lo_add_fd_mapping(req, fd);
+ pthread_mutex_unlock(&lo->mutex);
+ if (fh == -1) {
+ close(fd);
+ fuse_reply_err(req, ENOMEM);
+ return;
+ }
+
+ fi->fh = fh;
if (lo->cache == CACHE_NEVER)
fi->direct_io = 1;
else if (lo->cache == CACHE_ALWAYS)
@@ -1120,9 +1176,18 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi)
static void lo_release(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info
*fi)
{
+ struct lo_data *lo = lo_data(req);
+ int fd;
+
(void) ino;
- close(fi->fh);
+ fd = lo_fi_fd(req, fi);
+
+ pthread_mutex_lock(&lo->mutex);
+ lo_map_remove(&lo->fd_map, fi->fh);
+ pthread_mutex_unlock(&lo->mutex);
+
+ close(fd);
fuse_reply_err(req, 0);
}
@@ -1130,7 +1195,7 @@ static void lo_flush(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi)
{
int res;
(void) ino;
- res = close(dup(fi->fh));
+ res = close(dup(lo_fi_fd(req, fi)));
fuse_reply_err(req, res == -1 ? errno : 0);
}
@@ -1155,7 +1220,7 @@ static void lo_fsync(fuse_req_t req, fuse_ino_t ino, int
datasync,
if (fd == -1)
return (void) fuse_reply_err(req, errno);
} else
- fd = fi->fh;
+ fd = lo_fi_fd(req, fi);
if (datasync)
res = fdatasync(fd);
@@ -1176,7 +1241,7 @@ static void lo_read(fuse_req_t req, fuse_ino_t ino,
size_t size,
"off=%lu)\n", ino, size, (unsigned long) offset);
buf.buf[0].flags = FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK;
- buf.buf[0].fd = fi->fh;
+ buf.buf[0].fd = lo_fi_fd(req, fi);
buf.buf[0].pos = offset;
fuse_reply_data(req, &buf, FUSE_BUF_SPLICE_MOVE);
@@ -1191,7 +1256,7 @@ static void lo_write_buf(fuse_req_t req, fuse_ino_t ino,
struct fuse_bufvec out_buf = FUSE_BUFVEC_INIT(fuse_buf_size(in_buf));
out_buf.buf[0].flags = FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK;
- out_buf.buf[0].fd = fi->fh;
+ out_buf.buf[0].fd = lo_fi_fd(req, fi);
out_buf.buf[0].pos = off;
if (lo_debug(req))
@@ -1234,7 +1299,8 @@ static void lo_fallocate(fuse_req_t req, fuse_ino_t ino,
int mode,
return;
}
- err = posix_fallocate(fi->fh, offset, length);
+ err = posix_fallocate(lo_fi_fd(req, fi), offset,
+ length);
#endif
fuse_reply_err(req, err);
@@ -1246,7 +1312,7 @@ static void lo_flock(fuse_req_t req, fuse_ino_t ino,
struct fuse_file_info *fi,
int res;
(void) ino;
- res = flock(fi->fh, op);
+ res = flock(lo_fi_fd(req, fi), op);
fuse_reply_err(req, res == -1 ? errno : 0);
}
@@ -1458,17 +1524,20 @@ static void lo_copy_file_range(fuse_req_t req,
fuse_ino_t ino_in, off_t off_in,
struct fuse_file_info *fi_out, size_t len,
int flags)
{
+ int in_fd, out_fd;
ssize_t res;
- if (lo_debug(req))
- fuse_log(FUSE_LOG_DEBUG, "lo_copy_file_range(ino=%" PRIu64
"/fd=%lu, "
- "off=%lu, ino=%" PRIu64 "/fd=%lu, "
- "off=%lu, size=%zd, flags=0x%x)\n",
- ino_in, fi_in->fh, off_in, ino_out, fi_out->fh, off_out,
- len, flags);
-
- res = copy_file_range(fi_in->fh, &off_in, fi_out->fh, &off_out, len,
- flags);
+ in_fd = lo_fi_fd(req, fi_in);
+ out_fd = lo_fi_fd(req, fi_out);
+
+ fuse_log(FUSE_LOG_DEBUG,
+ "lo_copy_file_range(ino=%" PRIu64 "/fd=%d, "
+ "off=%lu, ino=%" PRIu64 "/fd=%d, "
+ "off=%lu, size=%zd, flags=0x%x)\n",
+ ino_in, in_fd, off_in, ino_out, out_fd, off_out, len,
+ flags);
+
+ res = copy_file_range(in_fd, &off_in, out_fd, &off_out, len, flags);
if (res < 0)
fuse_reply_err(req, -errno);
else
@@ -1552,6 +1621,7 @@ int main(int argc, char *argv[])
root_elem->inode = &lo.root;
lo_map_init(&lo.dirp_map);
+ lo_map_init(&lo.fd_map);
if (fuse_parse_cmdline(&args, &opts) != 0)
return 1;
@@ -1646,6 +1716,7 @@ err_out2:
err_out1:
fuse_opt_free_args(&args);
+ lo_map_destroy(&lo.fd_map);
lo_map_destroy(&lo.dirp_map);
lo_map_destroy(&lo.ino_map);
--
2.23.0
