Add validation in virtio-fs to ensure the server follows the FUSE protocol for response headers, addressing the existing TODO for verifying protocol compliance.
Add checks for fuse_out_header to verify: - oh->unique matches req->in.h.unique - FUSE_INT_REQ_BIT is not set - error codes are valid - oh->len does not exceed the expected size Signed-off-by: Brajesh Patil <[email protected]> --- fs/fuse/virtio_fs.c | 30 +++++++++++++++++++++++++----- 1 file changed, 25 insertions(+), 5 deletions(-) diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c index 6bc7c97b017d..52e8338bf436 100644 --- a/fs/fuse/virtio_fs.c +++ b/fs/fuse/virtio_fs.c @@ -764,14 +764,34 @@ static void virtio_fs_request_complete(struct fuse_req *req, { struct fuse_args *args; struct fuse_args_pages *ap; - unsigned int len, i, thislen; + struct fuse_out_header *oh; + unsigned int len, i, thislen, expected_len = 0; struct folio *folio; - /* - * TODO verify that server properly follows FUSE protocol - * (oh.uniq, oh.len) - */ + oh = &req->out.h; + + if (oh->unique == 0) + pr_warn_once("notify through fuse-virtio-fs not supported"); + + if ((oh->unique & ~FUSE_INT_REQ_BIT) != req->in.h.unique) + pr_warn_ratelimited("virtio-fs: unique mismatch, expected: %llu got %llu\n", + req->in.h.unique, oh->unique & ~FUSE_INT_REQ_BIT); + + WARN_ON_ONCE(oh->unique & FUSE_INT_REQ_BIT); + + if (oh->error <= -ERESTARTSYS || oh->error > 0) + pr_warn_ratelimited("virtio-fs: invalid error code from server: %d\n", + oh->error); + args = req->args; + + for (i = 0; i < args->out_numargs; i++) + expected_len += args->out_args[i].size; + + if (oh->len > sizeof(*oh) + expected_len) + pr_warn("FUSE reply too long! got=%u expected<=%u\n", + oh->len, (unsigned int)(sizeof(*oh) + expected_len)); + copy_args_from_argbuf(args, req); if (args->out_pages && args->page_zeroing) { -- 2.43.0
