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[PATCH 033/104] virtiofsd: passthrough_ll: add lo_map for ino/fh indirec
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[PATCH 033/104] virtiofsd: passthrough_ll: add lo_map for ino/fh indirection |
Date: |
Thu, 12 Dec 2019 16:37:53 +0000 |
From: Stefan Hajnoczi <address@hidden>
A layer of indirection is needed because passthrough_ll cannot expose
pointers or file descriptor numbers to untrusted clients. Malicious
clients could send invalid pointers or file descriptors in order to
crash or exploit the file system daemon.
lo_map provides an integer key->value mapping. This will be used for
ino and fh fields in the patches that follow.
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
tools/virtiofsd/passthrough_ll.c | 124 +++++++++++++++++++++++++++++++
1 file changed, 124 insertions(+)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 0188cd9ad6..0a94c3e1f2 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -74,6 +74,21 @@ struct _uintptr_to_must_hold_fuse_ino_t_dummy_struct {
};
#endif
+struct lo_map_elem {
+ union {
+ /* Element values will go here... */
+ ssize_t freelist;
+ };
+ bool in_use;
+};
+
+/* Maps FUSE fh or ino values to internal objects */
+struct lo_map {
+ struct lo_map_elem *elems;
+ size_t nelems;
+ ssize_t freelist;
+};
+
struct lo_inode {
struct lo_inode *next; /* protected by lo->mutex */
struct lo_inode *prev; /* protected by lo->mutex */
@@ -130,6 +145,115 @@ static struct lo_data *lo_data(fuse_req_t req)
return (struct lo_data *)fuse_req_userdata(req);
}
+__attribute__((unused)) static void lo_map_init(struct lo_map *map)
+{
+ map->elems = NULL;
+ map->nelems = 0;
+ map->freelist = -1;
+}
+
+__attribute__((unused)) static void lo_map_destroy(struct lo_map *map)
+{
+ free(map->elems);
+}
+
+static int lo_map_grow(struct lo_map *map, size_t new_nelems)
+{
+ struct lo_map_elem *new_elems;
+ size_t i;
+
+ if (new_nelems <= map->nelems) {
+ return 1;
+ }
+
+ new_elems = realloc(map->elems, sizeof(map->elems[0]) * new_nelems);
+ if (!new_elems) {
+ return 0;
+ }
+
+ for (i = map->nelems; i < new_nelems; i++) {
+ new_elems[i].freelist = i + 1;
+ new_elems[i].in_use = false;
+ }
+ new_elems[new_nelems - 1].freelist = -1;
+
+ map->elems = new_elems;
+ map->freelist = map->nelems;
+ map->nelems = new_nelems;
+ return 1;
+}
+
+__attribute__((unused)) static struct lo_map_elem *
+lo_map_alloc_elem(struct lo_map *map)
+{
+ struct lo_map_elem *elem;
+
+ if (map->freelist == -1 && !lo_map_grow(map, map->nelems + 256)) {
+ return NULL;
+ }
+
+ elem = &map->elems[map->freelist];
+ map->freelist = elem->freelist;
+
+ elem->in_use = true;
+
+ return elem;
+}
+
+__attribute__((unused)) static struct lo_map_elem *
+lo_map_reserve(struct lo_map *map, size_t key)
+{
+ ssize_t *prev;
+
+ if (!lo_map_grow(map, key + 1)) {
+ return NULL;
+ }
+
+ for (prev = &map->freelist; *prev != -1;
+ prev = &map->elems[*prev].freelist) {
+ if (*prev == key) {
+ struct lo_map_elem *elem = &map->elems[key];
+
+ *prev = elem->freelist;
+ elem->in_use = true;
+ return elem;
+ }
+ }
+ return NULL;
+}
+
+__attribute__((unused)) static struct lo_map_elem *
+lo_map_get(struct lo_map *map, size_t key)
+{
+ if (key >= map->nelems) {
+ return NULL;
+ }
+ if (!map->elems[key].in_use) {
+ return NULL;
+ }
+ return &map->elems[key];
+}
+
+__attribute__((unused)) static void lo_map_remove(struct lo_map *map,
+ size_t key)
+{
+ struct lo_map_elem *elem;
+
+ if (key >= map->nelems) {
+ return;
+ }
+
+ elem = &map->elems[key];
+ if (!elem->in_use) {
+ return;
+ }
+
+ elem->in_use = false;
+
+ elem->freelist = map->freelist;
+ map->freelist = key;
+}
+
static struct lo_inode *lo_inode(fuse_req_t req, fuse_ino_t ino)
{
if (ino == FUSE_ROOT_ID) {
--
2.23.0
- [PATCH 024/104] virtiofsd: Keep track of replies, (continued)
- [PATCH 024/104] virtiofsd: Keep track of replies, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 026/104] virtiofsd: Fast path for virtio read, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 027/104] virtiofsd: add --fd=FDNUM fd passing option, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 022/104] virtiofsd: Start reading commands from queue, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 023/104] virtiofsd: Send replies to messages, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 030/104] virtiofsd: add --print-capabilities option, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 031/104] virtiofs: Add maintainers entry, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 028/104] virtiofsd: make -f (foreground) the default, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 029/104] virtiofsd: add vhost-user.json file, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 032/104] virtiofsd: passthrough_ll: create new files in caller's context, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 033/104] virtiofsd: passthrough_ll: add lo_map for ino/fh indirection,
Dr. David Alan Gilbert (git) <=
- [PATCH 034/104] virtiofsd: passthrough_ll: add ino_map to hide lo_inode pointers, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 036/104] virtiofsd: passthrough_ll: add fd_map to hide file descriptors, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 037/104] virtiofsd: passthrough_ll: add fallback for racy ops, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 038/104] virtiofsd: validate path components, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 040/104] virtiofsd: Pass write iov's all the way through, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 039/104] virtiofsd: Plumb fuse_bufvec through to do_write_buf, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 035/104] virtiofsd: passthrough_ll: add dirp_map to hide lo_dirp pointers, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 041/104] virtiofsd: add fuse_mbuf_iter API, Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 042/104] virtiofsd: validate input buffer sizes in do_write_buf(), Dr. David Alan Gilbert (git), 2019/12/12
- [PATCH 044/104] virtiofsd: prevent ".." escape in lo_do_lookup(), Dr. David Alan Gilbert (git), 2019/12/12