From patchwork Sat Oct 7 20:51:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lorenzo Stoakes X-Patchwork-Id: 13412489 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 C5EBF30FB1 for ; Sat, 7 Oct 2023 20:51:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="TfR9S7iZ" Received: from mail-wr1-x42e.google.com (mail-wr1-x42e.google.com [IPv6:2a00:1450:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D685EB9; Sat, 7 Oct 2023 13:51:12 -0700 (PDT) Received: by mail-wr1-x42e.google.com with SMTP id ffacd0b85a97d-3296b87aa13so1498169f8f.3; Sat, 07 Oct 2023 13:51:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1696711871; x=1697316671; 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=OgUbWzhgbQTh2Tsrre/VRjjQqlOhd22889mYfV2Y6PM=; b=TfR9S7iZqWd68vkAG78o8osauyeVyv21OxFixVbIkzSvoBOM2Nc3ZB666TI0MVNcwe CLSaAaJ4dwmJlACIc31kfIf1eG4jMiWe/+E4dftKQQaBrOOP2VOuXuDiS6fm1Mo+Bm/U Bj4tfqH/d8Qc0Vc+DC4720Y8XaS9ykYbFVHxFx07G7NgX3/k4UJBPTw4vsZUKETjMOot 9+mWT2mcw7uwYv5xEpnOwibVIgNtLqgWUIR1QYgEGY5Byjdr9nz8l/bn42RsF7KJtzIT /sMoq5QgYSSi3FmbtS7jyBErJ+SpbxR5DKq7zQC0Xoil1dIMpc4hAq+KF3MUWVsLiKi0 g6Fg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696711871; x=1697316671; 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=OgUbWzhgbQTh2Tsrre/VRjjQqlOhd22889mYfV2Y6PM=; b=wjDK6XrQANyjj3zmYMZW4bpqvO0cRiUC24N1c4+TXmNJOZBccWQZTXTEFPQdUQS0fh vU8DGx/jcotcv62oo+dQ/jNJBAfsd1BB2wBVLAmIxVqx+h6VnHHAC//IGy7++iWWG+04 vlhQIVZrOha8ynYzLhw2Hzj1sMnQm+Lpo590WC3V04IKHkYHO52GRsbuYPz+1JKXArSy 7J43JVEVn3oiorTsV/HSUOmXC7Zgx7z8Ep7KXrdii0lQ/OeD85GpjLecaKmUGakAHXO8 ofPHT8KEbUPHZZu6cLyoVU5XN9eYGnbZG8v7Uz41WENeO+GDXaL/ugwwvK5y9n89aT9D 9dzg== X-Gm-Message-State: AOJu0YxN53ELhqrZtleu4yjdlBg0vLDNYG717suU/XttMYdLyNlVBFqF 7MPuRr55o6yNottVCfU2l6c= X-Google-Smtp-Source: AGHT+IEXmITz4RMxLO9GqG7a0wyR3fIBUWZzSpv/XJYSngX65HmU/52/H9zjUYWovmJKhPLVZlC06A== X-Received: by 2002:adf:f005:0:b0:326:c623:3bbf with SMTP id j5-20020adff005000000b00326c6233bbfmr11078774wro.26.1696711871254; Sat, 07 Oct 2023 13:51:11 -0700 (PDT) Received: from lucifer.home ([2a00:23c5:dc8c:8701:1663:9a35:5a7b:1d76]) by smtp.googlemail.com with ESMTPSA id g7-20020adfe407000000b003232d122dbfsm5120550wrm.66.2023.10.07.13.51.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Oct 2023 13:51:10 -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 v3 2/3] mm: update memfd seal write check to include F_SEAL_WRITE Date: Sat, 7 Oct 2023 21:51:00 +0100 Message-ID: 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 --- 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 c9e9628addc4..51a217ed4d1b 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4027,25 +4027,26 @@ 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;