From patchwork Thu Oct 12 17:04:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lorenzo Stoakes X-Patchwork-Id: 13419475 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 5A88B339BD; Thu, 12 Oct 2023 17:04:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="VB1q1Jf2" Received: from mail-wm1-x335.google.com (mail-wm1-x335.google.com [IPv6:2a00:1450:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DDA14CA; Thu, 12 Oct 2023 10:04:37 -0700 (PDT) Received: by mail-wm1-x335.google.com with SMTP id 5b1f17b1804b1-406618d0991so12457525e9.2; Thu, 12 Oct 2023 10:04:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1697130276; x=1697735076; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=7LHgfYhq7AemM3CMY63djM9UPMuGnWJ3Ca40aCfcDv0=; b=VB1q1Jf2KTBfKkAWvU9qEjXoDf8EcFQY2qWhHU0U27kgdiu+ldcbi/Vb5dLj0DsIGw ZKg6aaCr1gaJ3JfcFnSY4FmrVb/gt27L3RC7RUUbradrlwS19z+6v8cV4M1iBQTjJPeb Odoi0FQ6eIZs2Nf96dYusIL8Fg+gcBDXh++1+FVMzVooEuppb4R6+F2Tu6lc9QP0RvgO AgxZBppa+wLnRSIehuxili6+kqle0ByGYOO1s+ArNxL43SSQcQaZCrRcEb98+iGV+lHR TISTPipnTR2PGGGXVq1e6zKCl2c1Q+Xb9fnH/84rKy2gGrmoIuVP7OMlGiXEh67r6UA0 9SZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1697130276; x=1697735076; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=7LHgfYhq7AemM3CMY63djM9UPMuGnWJ3Ca40aCfcDv0=; b=Tewgxr3cDAE8aFl+Lk79wFYAcQ2nfS0YBDlZ6yjU1X6UOZsYHbYzdT+fXCsQOQAExB ETjVQTIFU5fldNIWj0TGNMOvb6Co8yIFCCO/aG79MQMtpIaNcNdexDc9DKl0TnBTIICX 4IC8L/yCGS+WWbgRb4e1aP7gL33v40v1TjFWraAzkBgQdmVg4x8/lHmyTOg9YC84rEbI hbbiU2PB13/JAhnhTBh1/qkNuKi4T9CofiR+JFVDuTveT/8Fe+W1KcIV5qPFakOCJWhB cJYKGmWUWFVlMWjzDUvXi5okILXNqQWn3KJs+7GbI2ahk7BJ7/cOA7tr16zA6N/bumUp u2YQ== X-Gm-Message-State: AOJu0YyiYa5iv0L+NnWaHcX/Vu3cV1A5dxcI7JMVNasrIUAJumbj97Lz kPIGOfXWb4MEAsqXEHEO/Cc= X-Google-Smtp-Source: AGHT+IH0xAcE4YpN2PK6WqZDga4ztB5LkRYTzIVE53cOl8uKk2DQm6dZmFs1iPawW4LIUtQS3pkW5Q== X-Received: by 2002:a5d:628a:0:b0:320:bb1:5a73 with SMTP id k10-20020a5d628a000000b003200bb15a73mr21972024wru.22.1697130276078; Thu, 12 Oct 2023 10:04:36 -0700 (PDT) Received: from lucifer.home ([2a00:23c5:dc8c:8701:1663:9a35:5a7b:1d76]) by smtp.googlemail.com with ESMTPSA id h16-20020adffd50000000b003197869bcd7sm18875418wrs.13.2023.10.12.10.04.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Oct 2023 10:04:34 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton Cc: Mike Kravetz , Muchun Song , Alexander Viro , Christian Brauner , Matthew Wilcox , Hugh Dickins , Andy Lutomirski , Jan Kara , linux-fsdevel@vger.kernel.org, bpf@vger.kernel.org, Lorenzo Stoakes Subject: [PATCH v4 2/3] mm: update memfd seal write check to include F_SEAL_WRITE Date: Thu, 12 Oct 2023 18:04:29 +0100 Message-ID: <913628168ce6cce77df7d13a63970bae06a526e0.1697116581.git.lstoakes@gmail.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net The seal_check_future_write() function is called by shmem_mmap() or hugetlbfs_file_mmap() to disallow any future writable mappings of an memfd sealed this way. The F_SEAL_WRITE flag is not checked here, as that is handled via the mapping->i_mmap_writable mechanism and so any attempt at a mapping would fail before this could be run. However we intend to change this, meaning this check can be performed for F_SEAL_WRITE mappings also. The logic here is equally applicable to both flags, so update this function to accommodate both and rename it accordingly. Signed-off-by: Lorenzo Stoakes Reviewed-by: Jan Kara --- fs/hugetlbfs/inode.c | 2 +- include/linux/mm.h | 15 ++++++++------- mm/shmem.c | 2 +- 3 files changed, 10 insertions(+), 9 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 06693bb1153d..5c333373dcc9 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -112,7 +112,7 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma) vm_flags_set(vma, VM_HUGETLB | VM_DONTEXPAND); vma->vm_ops = &hugetlb_vm_ops; - ret = seal_check_future_write(info->seals, vma); + ret = seal_check_write(info->seals, vma); if (ret) return ret; diff --git a/include/linux/mm.h b/include/linux/mm.h index bae234d18d81..26d7dc3b342b 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4078,25 +4078,26 @@ static inline void mem_dump_obj(void *object) {} #endif /** - * seal_check_future_write - Check for F_SEAL_FUTURE_WRITE flag and handle it + * seal_check_write - Check for F_SEAL_WRITE or F_SEAL_FUTURE_WRITE flags and + * handle them. * @seals: the seals to check * @vma: the vma to operate on * - * Check whether F_SEAL_FUTURE_WRITE is set; if so, do proper check/handling on - * the vma flags. Return 0 if check pass, or <0 for errors. + * Check whether F_SEAL_WRITE or F_SEAL_FUTURE_WRITE are set; if so, do proper + * check/handling on the vma flags. Return 0 if check pass, or <0 for errors. */ -static inline int seal_check_future_write(int seals, struct vm_area_struct *vma) +static inline int seal_check_write(int seals, struct vm_area_struct *vma) { - if (seals & F_SEAL_FUTURE_WRITE) { + if (seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) { /* * New PROT_WRITE and MAP_SHARED mmaps are not allowed when - * "future write" seal active. + * write seals are active. */ if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE)) return -EPERM; /* - * Since an F_SEAL_FUTURE_WRITE sealed memfd can be mapped as + * Since an F_SEAL_[FUTURE_]WRITE sealed memfd can be mapped as * MAP_SHARED and read-only, take care to not allow mprotect to * revert protections on such mappings. Do this only for shared * mappings. For private mappings, don't need to mask diff --git a/mm/shmem.c b/mm/shmem.c index 6503910b0f54..cab053831fea 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2405,7 +2405,7 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma) struct shmem_inode_info *info = SHMEM_I(inode); int ret; - ret = seal_check_future_write(info->seals, vma); + ret = seal_check_write(info->seals, vma); if (ret) return ret;