From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fhigh6-smtp.messagingengine.com (fhigh6-smtp.messagingengine.com [103.168.172.157]) (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 8761A3FB94 for ; Mon, 8 Jul 2024 13:06:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=103.168.172.157 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720443972; cv=none; b=ig7OHzLxoBdfpjxb22onpBYOzIaLZcDiNociPAqITrcYvK+IRK02xaqQuNTVrQFpkhI7c+GIWkT1NHYZpbBZ5QCTdggRziGEx0mOEgGu+xDUMXVqwJcbb6wl0+wrsL5I9xswns0zv4tE4ml6FIwZVIusHs5Ps8XtFmjglf74vSU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720443972; c=relaxed/simple; bh=wmlQlEjfvU0upTUltYjtMZhhx4tjODYQEOWVs4pNx7E=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gOsV7IWsuA6JBZBjcRoprNHIk5XuzCzp4rVwi0d+hhLDK/wiBg3T4iCXw6YGzBcAOtgbEfzEVofj15+lqxKaBGLavKl/ghtd5sdJJNtxmdjH36HKCkUh4SaaJH8VRKC8QfNIRx+cWnqN67nnzcKx2SDbi3u+AQNidKfAR2uqqkM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=kroah.com; spf=pass smtp.mailfrom=kroah.com; dkim=pass (2048-bit key) header.d=kroah.com header.i=@kroah.com header.b=cHZdbewp; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=R/gEt/IL; arc=none smtp.client-ip=103.168.172.157 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=kroah.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kroah.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kroah.com header.i=@kroah.com header.b="cHZdbewp"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="R/gEt/IL" Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by mailfhigh.nyi.internal (Postfix) with ESMTP id 716781140094; Mon, 8 Jul 2024 09:06:09 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute5.internal (MEProxy); Mon, 08 Jul 2024 09:06:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kroah.com; h=cc :cc:content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:subject :subject:to:to; s=fm2; t=1720443969; x=1720530369; bh=0SdS1gVeus EW5yio1Y8gYWXdzaFHasJ/BlKtWZGx4kI=; b=cHZdbewpg+ViuSQAtycyE5h5Jo c21qzFKSX61u/208aYlY2t8BMXOooj2UONpgyGTsqZSyyXtQp6mZBJt0SsH5BHJ+ JR5hlUqEJn4HbmmpBFcaS7vEsGoBtG3XvBaaoJpCx8aBVJYicMHTt8D+6Gg9PMPY nIFUV59IlXZuG1YllMunLWhk7S8yhcCjVsbWnywlHrB6OsfU+czoYjTLh9ao/M7X MNjfV0eybFH85NWpGjAf+3kjISkX3I9ybA/VgrFEdMRFMTM5aba5ThtZzPjsQTem hkNDpfXS2Gwe8gc50AwGBa93HYSeea2/D5oncKeAk3xxO0K9li98rRcJaU+Q== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:subject:subject:to :to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm2; t=1720443969; x=1720530369; bh=0SdS1gVeusEW5yio1Y8gYWXdzaFH asJ/BlKtWZGx4kI=; b=R/gEt/ILT2PDanPuenJaiEvRh12JcAjEJMdN85lZZIcG TaRErGIDx0Qd4+E3wpF5ZhxpidVoJ6E6mFm6PGl68KECngGVjaDNUojFHsE8+faw 1XiwH2mXCmCQJgVSX7JZXLHzCbVfVXEXlaNGhMbYujXmN3OvF9Nu5omm8q3y/12B JUDZj8v35XfaUxFpjoIY/1kS0ofRGqteG5sSN10cHs+7KeX3gGMM6uI73bVJUB/e S+APa742tHUnZdLwSXWsWcbzYVioxqXRTaJc0c9rRfitSpoXA4lGEwD3s8OHQgL7 6HSCPASfp9w+qjh+OHwr9zfdrXaiUSQ2UXTH1xBh9Q== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeeftddrvdejgdehlecutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpeffhffvvefukfhfgggtuggjsehttdertddttddvnecuhfhrohhmpefirhgvghcu mffjuceoghhrvghgsehkrhhorghhrdgtohhmqeenucggtffrrghtthgvrhhnpeehgedvve dvleejuefgtdduudfhkeeltdeihfevjeekjeeuhfdtueefhffgheekteenucevlhhushht vghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehgrhgvgheskhhrohgrhh drtghomh X-ME-Proxy: Feedback-ID: i787e41f1:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Mon, 8 Jul 2024 09:06:06 -0400 (EDT) Date: Mon, 8 Jul 2024 15:06:01 +0200 From: Greg KH To: Roberto Sassu Cc: stable@vger.kernel.org, zohar@linux.ibm.com, GUO Zihua , John Johansen , Casey Schaufler , Paul Moore , Roberto Sassu Subject: Re: [PATCH] ima: Avoid blocking in RCU read-side critical section Message-ID: <2024070852-kelp-cuddly-1f0c@gregkh> References: <20240704104303.3330331-1-roberto.sassu@huaweicloud.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240704104303.3330331-1-roberto.sassu@huaweicloud.com> On Thu, Jul 04, 2024 at 12:43:03PM +0200, Roberto Sassu wrote: > From: GUO Zihua > > A panic happens in ima_match_policy: > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 > PGD 42f873067 P4D 0 > Oops: 0000 [#1] SMP NOPTI > CPU: 5 PID: 1286325 Comm: kubeletmonit.sh > Kdump: loaded Tainted: P > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > BIOS 0.0.0 02/06/2015 > RIP: 0010:ima_match_policy+0x84/0x450 > Code: 49 89 fc 41 89 cf 31 ed 89 44 24 14 eb 1c 44 39 > 7b 18 74 26 41 83 ff 05 74 20 48 8b 1b 48 3b 1d > f2 b9 f4 00 0f 84 9c 01 00 00 <44> 85 73 10 74 ea > 44 8b 6b 14 41 f6 c5 01 75 d4 41 f6 c5 02 74 0f > RSP: 0018:ff71570009e07a80 EFLAGS: 00010207 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000200 > RDX: ffffffffad8dc7c0 RSI: 0000000024924925 RDI: ff3e27850dea2000 > RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffffabfce739 > R10: ff3e27810cc42400 R11: 0000000000000000 R12: ff3e2781825ef970 > R13: 00000000ff3e2785 R14: 000000000000000c R15: 0000000000000001 > FS: 00007f5195b51740(0000) > GS:ff3e278b12d40000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000010 CR3: 0000000626d24002 CR4: 0000000000361ee0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > ima_get_action+0x22/0x30 > process_measurement+0xb0/0x830 > ? page_add_file_rmap+0x15/0x170 > ? alloc_set_pte+0x269/0x4c0 > ? prep_new_page+0x81/0x140 > ? simple_xattr_get+0x75/0xa0 > ? selinux_file_open+0x9d/0xf0 > ima_file_check+0x64/0x90 > path_openat+0x571/0x1720 > do_filp_open+0x9b/0x110 > ? page_counter_try_charge+0x57/0xc0 > ? files_cgroup_alloc_fd+0x38/0x60 > ? __alloc_fd+0xd4/0x250 > ? do_sys_open+0x1bd/0x250 > do_sys_open+0x1bd/0x250 > do_syscall_64+0x5d/0x1d0 > entry_SYSCALL_64_after_hwframe+0x65/0xca > > Commit c7423dbdbc9e ("ima: Handle -ESTALE returned by > ima_filter_rule_match()") introduced call to ima_lsm_copy_rule within a > RCU read-side critical section which contains kmalloc with GFP_KERNEL. > This implies a possible sleep and violates limitations of RCU read-side > critical sections on non-PREEMPT systems. > > Sleeping within RCU read-side critical section might cause > synchronize_rcu() returning early and break RCU protection, allowing a > UAF to happen. > > The root cause of this issue could be described as follows: > | Thread A | Thread B | > | |ima_match_policy | > | | rcu_read_lock | > |ima_lsm_update_rule | | > | synchronize_rcu | | > | | kmalloc(GFP_KERNEL)| > | | sleep | > ==> synchronize_rcu returns early > | kfree(entry) | | > | | entry = entry->next| > ==> UAF happens and entry now becomes NULL (or could be anything). > | | entry->action | > ==> Accessing entry might cause panic. > > To fix this issue, we are converting all kmalloc that is called within > RCU read-side critical section to use GFP_ATOMIC. > > Fixes: c7423dbdbc9e ("ima: Handle -ESTALE returned by ima_filter_rule_match()") > Cc: stable@vger.kernel.org > Signed-off-by: GUO Zihua > Acked-by: John Johansen > Reviewed-by: Mimi Zohar > Reviewed-by: Casey Schaufler > [PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case] > Signed-off-by: Paul Moore > (cherry picked from commit 9a95c5bfbf02a0a7f5983280fe284a0ff0836c34) > Signed-off-by: Roberto Sassu > --- > Backporting notes: > - Remove security_audit_rule_init() documentation changes > - Add default return value parameter to call_int_hook() > in security_audit_rule_init() > - Can be backported to 6.1.x, 5.15.x, 5.10.x Now queued up, thanks. greg k-h