From patchwork Thu Oct 18 06:59:07 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 10646775 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DEFC41508 for ; Thu, 18 Oct 2018 06:59:21 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D0C5D287BB for ; Thu, 18 Oct 2018 06:59:21 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C4BC8287F4; Thu, 18 Oct 2018 06:59:21 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=unavailable version=3.3.1 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 30EF3287F3 for ; Thu, 18 Oct 2018 06:59:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E66F26B000E; Thu, 18 Oct 2018 02:59:19 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id E16E26B0010; Thu, 18 Oct 2018 02:59:19 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D06EA6B0266; Thu, 18 Oct 2018 02:59:19 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from mail-pg1-f199.google.com (mail-pg1-f199.google.com [209.85.215.199]) by kanga.kvack.org (Postfix) with ESMTP id 8F27D6B000E for ; Thu, 18 Oct 2018 02:59:19 -0400 (EDT) Received: by mail-pg1-f199.google.com with SMTP id b7-v6so21853840pgt.10 for ; Wed, 17 Oct 2018 23:59:19 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:from:to:cc:subject:date :message-id:mime-version:content-transfer-encoding; bh=Xear+RLNnBEI0/eVpUZWOmlWkAdxU+7aAlsATSKFP7M=; b=E0RQ7ZSq4JTW19PbGQh9S6s06+yUjc7NZBYGnAtGd0iozYxj4LB/bWGhMXU8lMMkPM nACZ/l8PP6wwclk1zq9MnG/XM0gQsPNlCiQfaMlORPK42JBWqXyUU26/u31taay4pBSI aoiyockFAnVsYSerECqpcOt9VxK8RDuJZdMT3PyCO0+IDz3SB0TSEQ64egXaAL7XeYam lyyKdh2vjUe82xDEExqmcVj2PLyt3IxcJ1ZCWlzjZL1tyXKECV3OHPvrDKInKLvTPp3+ dX0dVNh+hv9knWj7W98sa6phEpfMuQwLedA3lh/uDN7boxP9OdEsZhWYDMjuuxwdNlWO lVbw== X-Gm-Message-State: ABuFfojJXiFN7i7oMHp3IIv4lzcQRISeMHQfEnpyob4tDvl/tS9kj0Zm Yo2/8dCLTzwHSaKFewGgtoYTt4nB7KgKbj270j6YwPDEHCYDluG4F8tG3bqANAmUkxxkhrVLZEq L4XmBEe0sVYiX2ilI6dbqXL0RF7k+Lwa26OGtJ8s6DptgsiwnY3X3UeVVOk+LhaCuRU8KELwI+7 FUo/fEI+kFmN9TYWML5zAlNfYeULt4g6U01QPsjaSiJNCBdPa7MHOOu2CqQetQ6xTwV/9CpXTXT Itz/icIl6MDk90bmUo4RZYOKFHke+xCxbBH8Pp2gPyorPZoOAKnqDU6UaLXQe3A7MK6tuvtAFJW ieO07kOTLE72/mK48b1e++Na/dgeDAeujqOD0GodXCNzYDrPgpL9/CTg+Cg/LdhrnQeg9u54CxX A X-Received: by 2002:a63:9507:: with SMTP id p7-v6mr27527421pgd.449.1539845959229; Wed, 17 Oct 2018 23:59:19 -0700 (PDT) X-Received: by 2002:a63:9507:: with SMTP id p7-v6mr27527380pgd.449.1539845958212; Wed, 17 Oct 2018 23:59:18 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1539845958; cv=none; d=google.com; s=arc-20160816; b=FDqVwijAh/LjJRhT9caP+3PiRjSnceX89DDIuk4+AM1HbQpWCZbqIpwJ+DWPNYQ8H9 2stXx4fuD4XWpuHk/p2R/W13WivkQ4XWaoElSebDOG8AAoEtN3tX2OseducFWzHxD1a0 A2QwvEZnJbDt8U/Xeszv6+veKfGRk7qOJjo4BONwvC5IcgDLoV3LfQ3KA+dmoADzASWH hkNC7cWmqi5HK5LRHpAUBZEjGefzUVJh9/+xNeluahjD7HMI6C+sh4ufYJif0c/N2k54 dzh4pMHPMesJoyzmNKHlT78wzu0c6JMtdzioC5aEsTIGzEvx0FzmTTkO3Td0yQSuOr7p XAxQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:dkim-signature; bh=Xear+RLNnBEI0/eVpUZWOmlWkAdxU+7aAlsATSKFP7M=; b=C4o+ZIzeHE6zAoq208USGiRXXDep5yG78QTJu/FDQN5RxsNaYG4YWomqlkDIi2hz8a rk/T4rQi8Hlyyvc/QukjdagNxKSKSdQkPRSeDiQ4AJp+Lg4XwKNN0Hd1zts0Fs5oSNBq aPoUHMj4P3AJqr5/duf8nfj67LdzHGStvuMIpyIfQ8Bpz1yMQ2a+Nry7RMgukvMFpZBj nXX1gNKZRQKL3OtXC8LQ0CztgbEZT8WLo/X047u3BUVzKZYgpsdz+AqzWteSvSbjLNVo uLpWv0Z/eAyWZSaa+zAj8psiuTccBP70i6akltfTST98oh23zk2kd2QbC8A5ZAF9cWbq g/hg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@joelfernandes.org header.s=google header.b=Wfm7WNtn; spf=pass (google.com: domain of joel@joelfernandes.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=joel@joelfernandes.org Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id p17-v6sor9779502pge.11.2018.10.17.23.59.18 for (Google Transport Security); Wed, 17 Oct 2018 23:59:18 -0700 (PDT) Received-SPF: pass (google.com: domain of joel@joelfernandes.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@joelfernandes.org header.s=google header.b=Wfm7WNtn; spf=pass (google.com: domain of joel@joelfernandes.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=joel@joelfernandes.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Xear+RLNnBEI0/eVpUZWOmlWkAdxU+7aAlsATSKFP7M=; b=Wfm7WNtnSe1mOFGfqKBdRntjsGjuttEpU10k9RKeog5WXJ4GJeEB8W4LkPkkB6p5qt m0VAfP1IGy9EfgWauzMhEfHkXjnITorsjoe5qct0+kAEb7FmQ6lrAFpoRbx0WKmmIbsv cBjHAtotUSQYxzv+ZijepTDA6aV5uMFoaR+FI= X-Google-Smtp-Source: ACcGV61xNVH+I+unnVa85HggpBCokX4PPakDnkgxaXbTohriKoGLxj+MmqZCLQw34fZ/oUzP7/SshA== X-Received: by 2002:a63:f744:: with SMTP id f4-v6mr27668756pgk.410.1539845957462; Wed, 17 Oct 2018 23:59:17 -0700 (PDT) Received: from joelaf.mtv.corp.google.com ([2620:0:1000:1601:3aef:314f:b9ea:889f]) by smtp.gmail.com with ESMTPSA id r23-v6sm21580750pfh.79.2018.10.17.23.59.15 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Oct 2018 23:59:16 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, "Joel Fernandes (Google)" , jreck@google.com, john.stultz@linaro.org, tkjos@google.com, gregkh@linuxfoundation.org, hch@infradead.org, Al Viro , Andrew Morton , dancol@google.com, "J. Bruce Fields" , Jeff Layton , linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, marcandre.lureau@redhat.com, Mike Kravetz , minchan@kernel.org, Shuah Khan , Thomas Gleixner Subject: [PATCH v3 1/2] mm: Add an F_SEAL_FUTURE_WRITE seal to memfd Date: Wed, 17 Oct 2018 23:59:07 -0700 Message-Id: <20181018065908.254389-1-joel@joelfernandes.org> X-Mailer: git-send-email 2.19.1.331.ge82ca0e54c-goog MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Android uses ashmem for sharing memory regions. We are looking forward to migrating all usecases of ashmem to memfd so that we can possibly remove the ashmem driver in the future from staging while also benefiting from using memfd and contributing to it. Note staging drivers are also not ABI and generally can be removed at anytime. One of the main usecases Android has is the ability to create a region and mmap it as writeable, then add protection against making any "future" writes while keeping the existing already mmap'ed writeable-region active. This allows us to implement a usecase where receivers of the shared memory buffer can get a read-only view, while the sender continues to write to the buffer. See CursorWindow documentation in Android for more details: https://developer.android.com/reference/android/database/CursorWindow This usecase cannot be implemented with the existing F_SEAL_WRITE seal. To support the usecase, this patch adds a new F_SEAL_FUTURE_WRITE seal which prevents any future mmap and write syscalls from succeeding while keeping the existing mmap active. The following program shows the seal working in action: #include #include #include #include #include #include #include #define F_SEAL_FUTURE_WRITE 0x0010 #define REGION_SIZE (5 * 1024 * 1024) int memfd_create_region(const char *name, size_t size) { int ret; int fd = syscall(__NR_memfd_create, name, MFD_ALLOW_SEALING); if (fd < 0) return fd; ret = ftruncate(fd, size); if (ret < 0) { close(fd); return ret; } return fd; } int main() { int ret, fd; void *addr, *addr2, *addr3, *addr1; ret = memfd_create_region("test_region", REGION_SIZE); printf("ret=%d\n", ret); fd = ret; // Create map addr = mmap(0, REGION_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); if (addr == MAP_FAILED) printf("map 0 failed\n"); else printf("map 0 passed\n"); if ((ret = write(fd, "test", 4)) != 4) printf("write failed even though no future-write seal " "(ret=%d errno =%d)\n", ret, errno); else printf("write passed\n"); addr1 = mmap(0, REGION_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); if (addr1 == MAP_FAILED) perror("map 1 prot-write failed even though no seal\n"); else printf("map 1 prot-write passed as expected\n"); ret = fcntl(fd, F_ADD_SEALS, F_SEAL_FUTURE_WRITE | F_SEAL_GROW | F_SEAL_SHRINK); if (ret == -1) printf("fcntl failed, errno: %d\n", errno); else printf("future-write seal now active\n"); if ((ret = write(fd, "test", 4)) != 4) printf("write failed as expected due to future-write seal\n"); else printf("write passed (unexpected)\n"); addr2 = mmap(0, REGION_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); if (addr2 == MAP_FAILED) perror("map 2 prot-write failed as expected due to seal\n"); else printf("map 2 passed\n"); addr3 = mmap(0, REGION_SIZE, PROT_READ, MAP_SHARED, fd, 0); if (addr3 == MAP_FAILED) perror("map 3 failed\n"); else printf("map 3 prot-read passed as expected\n"); } The output of running this program is as follows: ret=3 map 0 passed write passed map 1 prot-write passed as expected future-write seal now active write failed as expected due to future-write seal map 2 prot-write failed as expected due to seal : Permission denied map 3 prot-read passed as expected Cc: jreck@google.com Cc: john.stultz@linaro.org Cc: tkjos@google.com Cc: gregkh@linuxfoundation.org Cc: hch@infradead.org Reviewed-by: John Stultz Signed-off-by: Joel Fernandes (Google) --- v1->v2: No change, just added selftests to the series. manpages are ready and I'll submit them once the patches are accepted. v2->v3: Updated commit message to have more support code (John Stultz) Renamed seal from F_SEAL_FS_WRITE to F_SEAL_FUTURE_WRITE (Christoph Hellwig) Allow for this seal only if grow/shrink seals are also either previous set, or are requested along with this seal. (Christoph Hellwig) Added locking to synchronize access to file->f_mode. (Christoph Hellwig) include/uapi/linux/fcntl.h | 1 + mm/memfd.c | 22 +++++++++++++++++++++- 2 files changed, 22 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h index 6448cdd9a350..a2f8658f1c55 100644 --- a/include/uapi/linux/fcntl.h +++ b/include/uapi/linux/fcntl.h @@ -41,6 +41,7 @@ #define F_SEAL_SHRINK 0x0002 /* prevent file from shrinking */ #define F_SEAL_GROW 0x0004 /* prevent file from growing */ #define F_SEAL_WRITE 0x0008 /* prevent writes */ +#define F_SEAL_FUTURE_WRITE 0x0010 /* prevent future writes while mapped */ /* (1U << 31) is reserved for signed error codes */ /* diff --git a/mm/memfd.c b/mm/memfd.c index 2bb5e257080e..5ba9804e9515 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -150,7 +150,8 @@ static unsigned int *memfd_file_seals_ptr(struct file *file) #define F_ALL_SEALS (F_SEAL_SEAL | \ F_SEAL_SHRINK | \ F_SEAL_GROW | \ - F_SEAL_WRITE) + F_SEAL_WRITE | \ + F_SEAL_FUTURE_WRITE) static int memfd_add_seals(struct file *file, unsigned int seals) { @@ -219,6 +220,25 @@ static int memfd_add_seals(struct file *file, unsigned int seals) } } + if ((seals & F_SEAL_FUTURE_WRITE) && + !(*file_seals & F_SEAL_FUTURE_WRITE)) { + /* + * The FUTURE_WRITE seal also prevents growing and shrinking + * so we need them to be already set, or requested now. + */ + int test_seals = (seals | *file_seals) & + (F_SEAL_GROW | F_SEAL_SHRINK); + + if (test_seals != (F_SEAL_GROW | F_SEAL_SHRINK)) { + error = -EINVAL; + goto unlock; + } + + spin_lock(&file->f_lock); + file->f_mode &= ~(FMODE_WRITE | FMODE_PWRITE); + spin_unlock(&file->f_lock); + } + *file_seals |= seals; error = 0; From patchwork Thu Oct 18 06:59:08 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 10646779 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 159DA109C for ; Thu, 18 Oct 2018 06:59:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 090F8287BB for ; Thu, 18 Oct 2018 06:59:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F07F8287F4; Thu, 18 Oct 2018 06:59:23 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=unavailable version=3.3.1 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8A376287BB for ; Thu, 18 Oct 2018 06:59:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 962976B0266; Thu, 18 Oct 2018 02:59:21 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 8E70B6B026A; Thu, 18 Oct 2018 02:59:21 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 764A96B0269; Thu, 18 Oct 2018 02:59:21 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) by kanga.kvack.org (Postfix) with ESMTP id 308B16B0010 for ; Thu, 18 Oct 2018 02:59:21 -0400 (EDT) Received: by mail-pl1-f200.google.com with SMTP id w12-v6so10572750plp.9 for ; Wed, 17 Oct 2018 23:59:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:from:to:cc:subject:date :message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=/VyGfWQacueEUHTGPoQ3uFdYU/4GyGaHaoBL4dBXqp8=; b=UMjyCBYAMo+4sLwrJyp5k4UZsS+l+Vnlff8QjhKp3/GQXOK38rBNq5L1VLA5b11rji 72DKtQIOOClnXOgG79ZJGjLL87qZMRIM6YgxKVDvAVpMmmKCwMkLMbE28U0FcZRHnduT dktVkYMZ9Jkf5yVdi3X4l85ai5PolniUT77WDg1hYsgdg9TLdUnvE9R0sg0DK3F9ZI5+ Q/X50+Xw6uGIpIjr8qmCECkWQ3SPBZDtaBpBaBQpfMaXddaX27ugqe5Yz7jo1iHUtEMH xv8nNlllOEzpPWF5hNT5ftyH/ybNBPhU2BF7zDdLmjgemGXHg6hUfuVx7rnx24KDPHDG onpw== X-Gm-Message-State: ABuFfogIgyaSTC3tfclPZFrU6GUngdkh0tVfrxs2D/G9pcEz3WtlBW6h Ksy+X3DSrB8IhpTcgpvsnP0k7QK9M7mcYI8qdlAJp8Uebv9knR7gpXEPzm5NECkXDlCIyZiNMAG NkW7doWbkzD7HphIRGvJM3C4yVoJ02u/8pEGpHuztVuCRFfQ1KCQmbYcipVkg1ueCp/I3RKyle1 Mo9FqnXoqDriE9kc//pjIkNXfID83+/URTMkGuIOVyX+xKLoOfNyteZQuqfz27kRpgEsk1H7s9O XDQwPIvQrnQSZu+8gRmueP+Ma3FoSXFN3ER/Ka/JmL1VC8duCP6xxv22DVF39xWhoKd0LB6LIRI TkY6A5JuRUTjCTsaIGq24z5yO9nebDdG3iBsPrHfs0+ftX1NhQo0V0bSQRVZKd5PZYVGz9he1rh Y X-Received: by 2002:a65:5508:: with SMTP id f8-v6mr27451883pgr.240.1539845960859; Wed, 17 Oct 2018 23:59:20 -0700 (PDT) X-Received: by 2002:a65:5508:: with SMTP id f8-v6mr27451858pgr.240.1539845960064; Wed, 17 Oct 2018 23:59:20 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1539845960; cv=none; d=google.com; s=arc-20160816; b=hByY7x9pvgE+YQQGfeJ04ur4F7uKafre6DXAyxzWpXMr/GovKTaWb6PO9FZZuzEgZv 4+gfImSdNhS6WmjSryIrjxnt+90J9Ct5VH9vDvrkiK+h+mbcZJ7837JDZgbFqc4tyLHX DT0C2p3jIQDjY2xsTavhUp7XR6yHcs7ndS5FVsTTo24O0cPOsTRQqWO76++SqwMkSm5y tJ1tFUgI+WOg+PIzKlwE1nUSzjYnByhexiI4iWTOjgb7+8yux83epWpjUPgUiHViKbUR /q4U/kHTUtUKaryZgYxiqFA/xfGM1GimT/F8Ybt0a3vvjubtULRliJ37RcbMTCGaFVoP cVag== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:dkim-signature; bh=/VyGfWQacueEUHTGPoQ3uFdYU/4GyGaHaoBL4dBXqp8=; b=rfJyFcJMP9EVB6MirQ6ekbboOD9r0tzePGb2fAqwvPwCfCIY7EXjSJcdIie+Pxj8x9 Yh1QfqQnB/zPCdGgT/axy7l6Y8uRGpwF6Kta0k1EJdb2oF+Ckp5aH4qv4cc7Pm6rQTxX pjkop2i6c0sroD0sce1ZaTrJUkkGKw6TgiXN6P6hMwbJBu14Ko4uK9ns6cmtYRr5WFbW F6cvJtCFMTBv6WWPIMm0ktivnysb8gYAjA7UoBywY0THHwml0phIzCbfu/oizMS1Ph7P ZJ6pIqGFyEf4+JAZQflaHPtSFImKCsBUjrRRUOe0QdnpTDLUpUd2nZU5pO4a9CQYYuKL nanw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@joelfernandes.org header.s=google header.b=DfksOTMP; spf=pass (google.com: domain of joel@joelfernandes.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=joel@joelfernandes.org Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id j189-v6sor1410320pgd.42.2018.10.17.23.59.19 for (Google Transport Security); Wed, 17 Oct 2018 23:59:20 -0700 (PDT) Received-SPF: pass (google.com: domain of joel@joelfernandes.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@joelfernandes.org header.s=google header.b=DfksOTMP; spf=pass (google.com: domain of joel@joelfernandes.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=joel@joelfernandes.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=/VyGfWQacueEUHTGPoQ3uFdYU/4GyGaHaoBL4dBXqp8=; b=DfksOTMPnGLSt+/RZVbtrmZH+aUqtKZ9anz+d0UFot8eCfcdCf686Kgfs2EwSZu5tI /paN5Ys1hMjJp+YCZH1bFHtPB2OgWbeFXPV3FmFTN9aWRdsDYc5RgLoKzciA+gXwfIw/ JIgYuws1P9Eb1SydvkYErc+X99w9lMAz/+IyQ= X-Google-Smtp-Source: ACcGV61MVMwfFrq1iY6mCNrXqt8vwRjugldQxLhW5AVm7ZVRL/BogArhefTux89TWrApAiEACQS/Uw== X-Received: by 2002:a63:7044:: with SMTP id a4-v6mr27475186pgn.63.1539845959538; Wed, 17 Oct 2018 23:59:19 -0700 (PDT) Received: from joelaf.mtv.corp.google.com ([2620:0:1000:1601:3aef:314f:b9ea:889f]) by smtp.gmail.com with ESMTPSA id r23-v6sm21580750pfh.79.2018.10.17.23.59.17 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Oct 2018 23:59:18 -0700 (PDT) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, "Joel Fernandes (Google)" , dancol@google.com, minchan@kernel.org, Al Viro , Andrew Morton , gregkh@linuxfoundation.org, "J. Bruce Fields" , Jeff Layton , John Stultz , jreck@google.com, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, marcandre.lureau@redhat.com, Mike Kravetz , Shuah Khan , Thomas Gleixner , tkjos@google.com Subject: [PATCH v3 2/2] selftests/memfd: Add tests for F_SEAL_FS_WRITE seal Date: Wed, 17 Oct 2018 23:59:08 -0700 Message-Id: <20181018065908.254389-2-joel@joelfernandes.org> X-Mailer: git-send-email 2.19.1.331.ge82ca0e54c-goog In-Reply-To: <20181018065908.254389-1-joel@joelfernandes.org> References: <20181018065908.254389-1-joel@joelfernandes.org> MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Add tests to verify sealing memfds with the F_SEAL_FS_WRITE works as expected. Cc: dancol@google.com Cc: minchan@kernel.org Reviewed-by: John Stultz Signed-off-by: Joel Fernandes (Google) --- tools/testing/selftests/memfd/memfd_test.c | 74 ++++++++++++++++++++++ 1 file changed, 74 insertions(+) diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 10baa1652fc2..32b207ca7372 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -692,6 +692,79 @@ static void test_seal_write(void) close(fd); } +/* + * Test SEAL_FUTURE_WRITE + * Test whether SEAL_FUTURE_WRITE actually prevents modifications. + */ +static void test_seal_future_write(void) +{ + int fd; + void *p; + + printf("%s SEAL-FUTURE-WRITE\n", memfd_str); + + fd = mfd_assert_new("kern_memfd_seal_future_write", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + + p = mfd_assert_mmap_shared(fd); + + mfd_assert_has_seals(fd, 0); + /* Not adding grow/shrink seals makes the future write + * seal fail to get added + */ + mfd_fail_add_seals(fd, F_SEAL_FUTURE_WRITE); + + mfd_assert_add_seals(fd, F_SEAL_GROW); + mfd_assert_has_seals(fd, F_SEAL_GROW); + + /* Should still fail since shrink seal has + * not yet been added + */ + mfd_fail_add_seals(fd, F_SEAL_FUTURE_WRITE); + + mfd_assert_add_seals(fd, F_SEAL_SHRINK); + mfd_assert_has_seals(fd, F_SEAL_GROW | + F_SEAL_SHRINK); + + /* Now should succeed, also verifies that the seal + * could be added with an existing writable mmap + */ + mfd_assert_add_seals(fd, F_SEAL_FUTURE_WRITE); + mfd_assert_has_seals(fd, F_SEAL_SHRINK | + F_SEAL_GROW | + F_SEAL_FUTURE_WRITE); + + /* read should pass, writes should fail */ + mfd_assert_read(fd); + mfd_fail_write(fd); + + munmap(p, mfd_def_size); + close(fd); + + /* Test adding all seals (grow, shrink, future write) at once */ + fd = mfd_assert_new("kern_memfd_seal_future_write2", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + + p = mfd_assert_mmap_shared(fd); + + mfd_assert_has_seals(fd, 0); + mfd_assert_add_seals(fd, F_SEAL_SHRINK | + F_SEAL_GROW | + F_SEAL_FUTURE_WRITE); + mfd_assert_has_seals(fd, F_SEAL_SHRINK | + F_SEAL_GROW | + F_SEAL_FUTURE_WRITE); + + /* read should pass, writes should fail */ + mfd_assert_read(fd); + mfd_fail_write(fd); + + munmap(p, mfd_def_size); + close(fd); +} + /* * Test SEAL_SHRINK * Test whether SEAL_SHRINK actually prevents shrinking @@ -945,6 +1018,7 @@ int main(int argc, char **argv) test_basic(); test_seal_write(); + test_seal_future_write(); test_seal_shrink(); test_seal_grow(); test_seal_resize();