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[PULL 035/108] virtiofsd: passthrough_ll: add lo_map for ino/fh indirect
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[PULL 035/108] virtiofsd: passthrough_ll: add lo_map for ino/fh indirection |
Date: |
Thu, 23 Jan 2020 16:45:17 +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>
Reviewed-by: Masayoshi Mizuma <address@hidden>
Signed-off-by: Dr. David Alan Gilbert <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 5e061797d4..e83a976587 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) {
--
2.24.1
- [PULL 025/108] virtiofsd: Send replies to messages, (continued)
- [PULL 025/108] virtiofsd: Send replies to messages, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 026/108] virtiofsd: Keep track of replies, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 023/108] virtiofsd: Poll kick_fd for queue, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 024/108] virtiofsd: Start reading commands from queue, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 027/108] virtiofsd: Add Makefile wiring for virtiofsd contrib, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 029/108] virtiofsd: add --fd=FDNUM fd passing option, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 031/108] virtiofsd: add vhost-user.json file, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 030/108] virtiofsd: make -f (foreground) the default, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 034/108] virtiofsd: passthrough_ll: create new files in caller's context, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 028/108] virtiofsd: Fast path for virtio read, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 035/108] virtiofsd: passthrough_ll: add lo_map for ino/fh indirection,
Dr. David Alan Gilbert (git) <=
- [PULL 033/108] virtiofs: Add maintainers entry, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 032/108] virtiofsd: add --print-capabilities option, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 037/108] virtiofsd: passthrough_ll: add dirp_map to hide lo_dirp pointers, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 036/108] virtiofsd: passthrough_ll: add ino_map to hide lo_inode pointers, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 038/108] virtiofsd: passthrough_ll: add fd_map to hide file descriptors, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 040/108] virtiofsd: validate path components, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 041/108] virtiofsd: Plumb fuse_bufvec through to do_write_buf, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 043/108] virtiofsd: add fuse_mbuf_iter API, Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 044/108] virtiofsd: validate input buffer sizes in do_write_buf(), Dr. David Alan Gilbert (git), 2020/01/23
- [PULL 046/108] virtiofsd: prevent ".." escape in lo_do_lookup(), Dr. David Alan Gilbert (git), 2020/01/23