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 C15DC1BC9F4 for ; Tue, 1 Oct 2024 07:24:43 +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=1727767483; cv=none; b=tHWgsZoHlgmuzxzGN+uMrB79pho5gPLIKsaC9dZcmI9IbzH5fvOgW3gR5UBOGhT+Uk5nnP14/DLfW8jtCUypGCZ4x1wTlVr0GJskHkBZsT2Saux+NItTpSXDE6OVfMfw+OnHyDnRBE4PklrXFVvqI2KZ8YGF4B540UDfHZtwcAY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727767483; c=relaxed/simple; bh=JH6MvO5bvZMML0TBdDavwB9OfRhIAA3o3Son99eulcY=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=HrtjkuxhH3p8D4Xl3RuBtSK8vW1SobC3vnPczotYDxAusPpzjJHdm9GSS5cP7DyOS2J5AVpvWo+zQBwNrY6D1Vf0Pq7GIbdPVcTE//fUwHY7UM+tgRbOtEpCjkQnN7nIz8k9SU/0awcGi+kF4xFhJBEeFKuAseZLW9hG8xJez3M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=mApstDFa; 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="mApstDFa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A3CCC4CEC6; Tue, 1 Oct 2024 07:24:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1727767483; bh=JH6MvO5bvZMML0TBdDavwB9OfRhIAA3o3Son99eulcY=; h=Subject:To:Cc:From:Date:From; b=mApstDFaD7BBwGTAYccYWpEe3Z0qWFSFP2nybyTMQ0VLsghCBsZNszGkM6N/VbcAP mK5hxSOU2o9JK4FX7RYIzudL66OB2w0sqfsnYaY/IQhqKv5ysXOkCut456AZ7ljKY0 skZTnXx1GkqVAkNjt+9kaX0tbfkB33Urxj08YnKs= Subject: FAILED: patch "[PATCH] mm: call the security_mmap_file() LSM hook in" failed to apply to 6.1-stable tree To: ebpqwerty472123@gmail.com,paul@paul-moore.com,stephen.smalley.work@gmail.com Cc: From: Date: Tue, 01 Oct 2024 09:24:40 +0200 Message-ID: <2024100139-mousiness-agreeable-1242@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-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 . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x ea7e2d5e49c05e5db1922387b09ca74aa40f46e2 # git commit -s git send-email --to '' --in-reply-to '2024100139-mousiness-agreeable-1242@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: ea7e2d5e49c0 ("mm: call the security_mmap_file() LSM hook in remap_file_pages()") 592b5fad1677 ("mm: Re-introduce vm_flags to do_mmap()") 183654ce26a5 ("mmap: change do_mas_munmap and do_mas_aligned_munmap() to use vma iterator") 0378c0a0e9e4 ("mm/mmap: remove preallocation from do_mas_align_munmap()") 92fed82047d7 ("mm/mmap: convert brk to use vma iterator") baabcfc93d3b ("mm/mmap: fix typo in comment") c5d5546ea065 ("maple_tree: remove the parameter entry of mas_preallocate") 675eaca1f441 ("mm/mmap: properly unaccount memory on mas_preallocate() failure") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From ea7e2d5e49c05e5db1922387b09ca74aa40f46e2 Mon Sep 17 00:00:00 2001 From: Shu Han Date: Tue, 17 Sep 2024 17:41:04 +0800 Subject: [PATCH] mm: call the security_mmap_file() LSM hook in remap_file_pages() The remap_file_pages syscall handler calls do_mmap() directly, which doesn't contain the LSM security check. And if the process has called personality(READ_IMPLIES_EXEC) before and remap_file_pages() is called for RW pages, this will actually result in remapping the pages to RWX, bypassing a W^X policy enforced by SELinux. So we should check prot by security_mmap_file LSM hook in the remap_file_pages syscall handler before do_mmap() is called. Otherwise, it potentially permits an attacker to bypass a W^X policy enforced by SELinux. The bypass is similar to CVE-2016-10044, which bypass the same thing via AIO and can be found in [1]. The PoC: $ cat > test.c int main(void) { size_t pagesz = sysconf(_SC_PAGE_SIZE); int mfd = syscall(SYS_memfd_create, "test", 0); const char *buf = mmap(NULL, 4 * pagesz, PROT_READ | PROT_WRITE, MAP_SHARED, mfd, 0); unsigned int old = syscall(SYS_personality, 0xffffffff); syscall(SYS_personality, READ_IMPLIES_EXEC | old); syscall(SYS_remap_file_pages, buf, pagesz, 0, 2, 0); syscall(SYS_personality, old); // show the RWX page exists even if W^X policy is enforced int fd = open("/proc/self/maps", O_RDONLY); unsigned char buf2[1024]; while (1) { int ret = read(fd, buf2, 1024); if (ret <= 0) break; write(1, buf2, ret); } close(fd); } $ gcc test.c -o test $ ./test | grep rwx 7f1836c34000-7f1836c35000 rwxs 00002000 00:01 2050 /memfd:test (deleted) Link: https://project-zero.issues.chromium.org/issues/42452389 [1] Cc: stable@vger.kernel.org Signed-off-by: Shu Han Acked-by: Stephen Smalley [PM: subject line tweaks] Signed-off-by: Paul Moore diff --git a/mm/mmap.c b/mm/mmap.c index d0dfc85b209b..18fddcce03b8 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3198,8 +3198,12 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, flags |= MAP_LOCKED; file = get_file(vma->vm_file); + ret = security_mmap_file(vma->vm_file, prot, flags); + if (ret) + goto out_fput; ret = do_mmap(vma->vm_file, start, size, prot, flags, 0, pgoff, &populate, NULL); +out_fput: fput(file); out: mmap_write_unlock(mm);