From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2DC8C47082 for ; Tue, 8 Jun 2021 12:21:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CC44D610FB for ; Tue, 8 Jun 2021 12:21:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232345AbhFHMXm (ORCPT ); Tue, 8 Jun 2021 08:23:42 -0400 Received: from wforward4-smtp.messagingengine.com ([64.147.123.34]:43633 "EHLO wforward4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232259AbhFHMXl (ORCPT ); Tue, 8 Jun 2021 08:23:41 -0400 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailforward.west.internal (Postfix) with ESMTP id 1C7B49BB; Tue, 8 Jun 2021 08:21:48 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute6.internal (MEProxy); Tue, 08 Jun 2021 08:21:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm3; bh=qcbn5e 29EFk/q1fh7UOAzR+R3YnDjgzg9oq7rmvMwE0=; b=AqVCUFKmWW3d1JjHuI+lzT zbu6P9XX47hskwNhZfLx8rDBlZRd4BP9PzQexsiueyZmY3u+iBAALj4m8bP++nf3 Kuz9TfolcnkZwKg7RtzL3Zy40GK92fnscCgdm684F83k1HATakv91GguAq+GU7Mm 4FmIBUbkguVtQZudGtZ186QDg7aFsumfg1lvewuWamrhS08vslHA/aZHUw2WD4Qx 45JuhlppsHZidFKyKgi0ypO6HM4jFMjD8Gyk5cX2in3p3ovMJrjQghUUVXQlq52d 67E+y/jj1vsPzdFi9lExD52lm8pCZdbkKCbpFGiHB85kJfv6XoyDojMNHOmSPSfg == X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrfedtledgfeehucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefuvffhfffkgggtgfesthekredttd dtlfenucfhrhhomhepoehgrhgvghhkhheslhhinhhugihfohhunhgurghtihhonhdrohhr gheqnecuggftrfgrthhtvghrnhepleelledvgeefleeltdetgedugeffgffhudffudduke egfeelgeeigeekjefhleevnecuffhomhgrihhnpehkvghrnhgvlhdrohhrghenucevlhhu shhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehgrhgvgheskhhroh grhhdrtghomh X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 8 Jun 2021 08:21:46 -0400 (EDT) Subject: FAILED: patch "[PATCH] fanotify: fix permission model of unprivileged group" failed to apply to 5.12-stable tree To: amir73il@gmail.com, Stable@vger.kernel.org, christian.brauner@ubuntu.com, jack@suse.cz, repnop@google.com Cc: From: Date: Tue, 08 Jun 2021 14:21:44 +0200 Message-ID: <162315490411353@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From a8b98c808eab3ec8f1b5a64be967b0f4af4cae43 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Mon, 24 May 2021 16:53:21 +0300 Subject: [PATCH] fanotify: fix permission model of unprivileged group Reporting event->pid should depend on the privileges of the user that initialized the group, not the privileges of the user reading the events. Use an internal group flag FANOTIFY_UNPRIV to record the fact that the group was initialized by an unprivileged user. To be on the safe side, the premissions to setup filesystem and mount marks now require that both the user that initialized the group and the user setting up the mark have CAP_SYS_ADMIN. Link: https://lore.kernel.org/linux-fsdevel/CAOQ4uxiA77_P5vtv7e83g0+9d7B5W9ZTE4GfQEYbWmfT1rA=VA@mail.gmail.com/ Fixes: 7cea2a3c505e ("fanotify: support limited functionality for unprivileged users") Cc: # v5.12+ Link: https://lore.kernel.org/r/20210524135321.2190062-1-amir73il@gmail.com Reviewed-by: Matthew Bobrowski Acked-by: Christian Brauner Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 71fefb30e015..be5b6d2c01e7 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -424,11 +424,18 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, * events generated by the listener process itself, without disclosing * the pids of other processes. */ - if (!capable(CAP_SYS_ADMIN) && + if (FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) && task_tgid(current) != event->pid) metadata.pid = 0; - if (path && path->mnt && path->dentry) { + /* + * For now, fid mode is required for an unprivileged listener and + * fid mode does not report fd in events. Keep this check anyway + * for safety in case fid mode requirement is relaxed in the future + * to allow unprivileged listener to get events with no fd and no fid. + */ + if (!FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) && + path && path->mnt && path->dentry) { fd = create_fd(group, path, &f); if (fd < 0) return fd; @@ -1040,6 +1047,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) int f_flags, fd; unsigned int fid_mode = flags & FANOTIFY_FID_BITS; unsigned int class = flags & FANOTIFY_CLASS_BITS; + unsigned int internal_flags = 0; pr_debug("%s: flags=%x event_f_flags=%x\n", __func__, flags, event_f_flags); @@ -1053,6 +1061,13 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) */ if ((flags & FANOTIFY_ADMIN_INIT_FLAGS) || !fid_mode) return -EPERM; + + /* + * Setting the internal flag FANOTIFY_UNPRIV on the group + * prevents setting mount/filesystem marks on this group and + * prevents reporting pid and open fd in events. + */ + internal_flags |= FANOTIFY_UNPRIV; } #ifdef CONFIG_AUDITSYSCALL @@ -1105,7 +1120,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) goto out_destroy_group; } - group->fanotify_data.flags = flags; + group->fanotify_data.flags = flags | internal_flags; group->memcg = get_mem_cgroup_from_mm(current->mm); group->fanotify_data.merge_hash = fanotify_alloc_merge_hash(); @@ -1305,11 +1320,13 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, group = f.file->private_data; /* - * An unprivileged user is not allowed to watch a mount point nor - * a filesystem. + * An unprivileged user is not allowed to setup mount nor filesystem + * marks. This also includes setting up such marks by a group that + * was initialized by an unprivileged user. */ ret = -EPERM; - if (!capable(CAP_SYS_ADMIN) && + if ((!capable(CAP_SYS_ADMIN) || + FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV)) && mark_type != FAN_MARK_INODE) goto fput_and_out; @@ -1460,6 +1477,7 @@ static int __init fanotify_user_setup(void) max_marks = clamp(max_marks, FANOTIFY_OLD_DEFAULT_MAX_MARKS, FANOTIFY_DEFAULT_MAX_USER_MARKS); + BUILD_BUG_ON(FANOTIFY_INIT_FLAGS & FANOTIFY_INTERNAL_GROUP_FLAGS); BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 10); BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9); diff --git a/fs/notify/fdinfo.c b/fs/notify/fdinfo.c index a712b2aaa9ac..57f0d5d9f934 100644 --- a/fs/notify/fdinfo.c +++ b/fs/notify/fdinfo.c @@ -144,7 +144,7 @@ void fanotify_show_fdinfo(struct seq_file *m, struct file *f) struct fsnotify_group *group = f->private_data; seq_printf(m, "fanotify flags:%x event-flags:%x\n", - group->fanotify_data.flags, + group->fanotify_data.flags & FANOTIFY_INIT_FLAGS, group->fanotify_data.f_flags); show_fdinfo(m, f, fanotify_fdinfo); diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h index bad41bcb25df..a16dbeced152 100644 --- a/include/linux/fanotify.h +++ b/include/linux/fanotify.h @@ -51,6 +51,10 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */ #define FANOTIFY_INIT_FLAGS (FANOTIFY_ADMIN_INIT_FLAGS | \ FANOTIFY_USER_INIT_FLAGS) +/* Internal group flags */ +#define FANOTIFY_UNPRIV 0x80000000 +#define FANOTIFY_INTERNAL_GROUP_FLAGS (FANOTIFY_UNPRIV) + #define FANOTIFY_MARK_TYPE_BITS (FAN_MARK_INODE | FAN_MARK_MOUNT | \ FAN_MARK_FILESYSTEM)