From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B44D512FB31; Wed, 19 Jun 2024 13:03:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718802199; cv=none; b=GH77KAJVoYSgI0HhDo7Ev1AfkgPrmj/hTrpOSc/l/f9T+S4qPZwBT0irKUTquAv/7IA1+nwv1YBkOGd+3VGa1wC5T6xN+2v3shZvwviVvW5fsx8C5e/tHy327GN6U2TlwEpOr4Dv1eZJsEqwzswbbd/s1JAfss5S0THhXZlosQw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718802199; c=relaxed/simple; bh=sXBHQhgrW9cC+lrBDaoNEeNb5aQaKTPGaKSrsWU54Jk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CFmt3qEB/lacAlOj3IXfjY509zp4Eq8UgjmZlDmfBiIhlXbXsiTdYofZMzAHv5hjxP3EC1i+2rJWvpSTgdBgvXcpK5clRP9QDlfXaCeXGwEx8ckgETD5LDq7/7P+0y1YKbmX5UWRIbQB3d8J4iocf5fxDlp3SkSVn0gjx/0Z7t8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gJJH5aLK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="gJJH5aLK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D1302C2BBFC; Wed, 19 Jun 2024 13:03:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1718802199; bh=sXBHQhgrW9cC+lrBDaoNEeNb5aQaKTPGaKSrsWU54Jk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gJJH5aLKt8BZENX8iksfBU/h9vMyZPgvSXRtvQgr+ZSeMX3Ot5BH1bUgKQ4raSOOX xR1d6o2PkUEAy8TxgLxZGjKQZ8bHGbr2R/5vhAYYaCflsLftlbuLxnBAneWKoESqHE 7IbiZpBiYdAjtBDSCAflChPbvBDR4EW4kRumYmn0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Hou Tao , Baokun Li , Jeff Layton , Christian Brauner , Sasha Levin Subject: [PATCH 6.6 114/267] cachefiles: defer exposing anon_fd until after copy_to_user() succeeds Date: Wed, 19 Jun 2024 14:54:25 +0200 Message-ID: <20240619125610.727127565@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240619125606.345939659@linuxfoundation.org> References: <20240619125606.345939659@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Baokun Li [ Upstream commit 4b4391e77a6bf24cba2ef1590e113d9b73b11039 ] After installing the anonymous fd, we can now see it in userland and close it. However, at this point we may not have gotten the reference count of the cache, but we will put it during colse fd, so this may cause a cache UAF. So grab the cache reference count before fd_install(). In addition, by kernel convention, fd is taken over by the user land after fd_install(), and the kernel should not call close_fd() after that, i.e., it should call fd_install() after everything is ready, thus fd_install() is called after copy_to_user() succeeds. Fixes: c8383054506c ("cachefiles: notify the user daemon when looking up cookie") Suggested-by: Hou Tao Signed-off-by: Baokun Li Link: https://lore.kernel.org/r/20240522114308.2402121-10-libaokun@huaweicloud.com Acked-by: Jeff Layton Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- fs/cachefiles/ondemand.c | 53 +++++++++++++++++++++++++--------------- 1 file changed, 33 insertions(+), 20 deletions(-) diff --git a/fs/cachefiles/ondemand.c b/fs/cachefiles/ondemand.c index 773c3b407a33b..a8cfa5047aaf8 100644 --- a/fs/cachefiles/ondemand.c +++ b/fs/cachefiles/ondemand.c @@ -4,6 +4,11 @@ #include #include "internal.h" +struct ondemand_anon_file { + struct file *file; + int fd; +}; + static inline void cachefiles_req_put(struct cachefiles_req *req) { if (refcount_dec_and_test(&req->ref)) @@ -250,14 +255,14 @@ int cachefiles_ondemand_restore(struct cachefiles_cache *cache, char *args) return 0; } -static int cachefiles_ondemand_get_fd(struct cachefiles_req *req) +static int cachefiles_ondemand_get_fd(struct cachefiles_req *req, + struct ondemand_anon_file *anon_file) { struct cachefiles_object *object; struct cachefiles_cache *cache; struct cachefiles_open *load; - struct file *file; u32 object_id; - int ret, fd; + int ret; object = cachefiles_grab_object(req->object, cachefiles_obj_get_ondemand_fd); @@ -269,16 +274,16 @@ static int cachefiles_ondemand_get_fd(struct cachefiles_req *req) if (ret < 0) goto err; - fd = get_unused_fd_flags(O_WRONLY); - if (fd < 0) { - ret = fd; + anon_file->fd = get_unused_fd_flags(O_WRONLY); + if (anon_file->fd < 0) { + ret = anon_file->fd; goto err_free_id; } - file = anon_inode_getfile("[cachefiles]", &cachefiles_ondemand_fd_fops, - object, O_WRONLY); - if (IS_ERR(file)) { - ret = PTR_ERR(file); + anon_file->file = anon_inode_getfile("[cachefiles]", + &cachefiles_ondemand_fd_fops, object, O_WRONLY); + if (IS_ERR(anon_file->file)) { + ret = PTR_ERR(anon_file->file); goto err_put_fd; } @@ -286,16 +291,15 @@ static int cachefiles_ondemand_get_fd(struct cachefiles_req *req) if (object->ondemand->ondemand_id > 0) { spin_unlock(&object->ondemand->lock); /* Pair with check in cachefiles_ondemand_fd_release(). */ - file->private_data = NULL; + anon_file->file->private_data = NULL; ret = -EEXIST; goto err_put_file; } - file->f_mode |= FMODE_PWRITE | FMODE_LSEEK; - fd_install(fd, file); + anon_file->file->f_mode |= FMODE_PWRITE | FMODE_LSEEK; load = (void *)req->msg.data; - load->fd = fd; + load->fd = anon_file->fd; object->ondemand->ondemand_id = object_id; spin_unlock(&object->ondemand->lock); @@ -304,9 +308,11 @@ static int cachefiles_ondemand_get_fd(struct cachefiles_req *req) return 0; err_put_file: - fput(file); + fput(anon_file->file); + anon_file->file = NULL; err_put_fd: - put_unused_fd(fd); + put_unused_fd(anon_file->fd); + anon_file->fd = ret; err_free_id: xa_erase(&cache->ondemand_ids, object_id); err: @@ -363,6 +369,7 @@ ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache, struct cachefiles_msg *msg; size_t n; int ret = 0; + struct ondemand_anon_file anon_file; XA_STATE(xas, &cache->reqs, cache->req_id_next); xa_lock(&cache->reqs); @@ -396,7 +403,7 @@ ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache, xa_unlock(&cache->reqs); if (msg->opcode == CACHEFILES_OP_OPEN) { - ret = cachefiles_ondemand_get_fd(req); + ret = cachefiles_ondemand_get_fd(req, &anon_file); if (ret) goto out; } @@ -404,10 +411,16 @@ ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache, msg->msg_id = xas.xa_index; msg->object_id = req->object->ondemand->ondemand_id; - if (copy_to_user(_buffer, msg, n) != 0) { + if (copy_to_user(_buffer, msg, n) != 0) ret = -EFAULT; - if (msg->opcode == CACHEFILES_OP_OPEN) - close_fd(((struct cachefiles_open *)msg->data)->fd); + + if (msg->opcode == CACHEFILES_OP_OPEN) { + if (ret < 0) { + fput(anon_file.file); + put_unused_fd(anon_file.fd); + goto out; + } + fd_install(anon_file.fd, anon_file.file); } out: cachefiles_put_object(req->object, cachefiles_obj_put_read_req); -- 2.43.0