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[209.85.220.65]) by mx.google.com with SMTPS id j5sor74321735qvj.70.2019.01.12.12.38.35 for (Google Transport Security); Sat, 12 Jan 2019 12:38:35 -0800 (PST) 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="lmKUV/dU"; 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=0MWo8Mkvt471260EQpjgHwB7ntQEkhWkiuroZZqGz7Q=; b=lmKUV/dUsPcqBbfMgv9BdXHViFVQX4L9qEX5mzBe6yCJ3IgEoApudENEMiWX9PcSia 78dwptQY2hD/6JHzCY7HMGBemp+tgjZhQ05kPp4parsICyeHICoGCaoIMK0aQJFKc8sR h8iqwys+YBCWX9ip/qKIEogwazXSfSq605vN4= X-Google-Smtp-Source: ALg8bN4EPzx3WrCu4lodXwGRW7peAjqqjPCeB/57bYpl+61/kVhWIFRuqh/Sb/FiGO3i6UC8/M6CjA== X-Received: by 2002:a0c:e751:: with SMTP id g17mr18871160qvn.160.1547325514848; Sat, 12 Jan 2019 12:38:34 -0800 (PST) Received: from joelaf.cam.corp.google.com ([2620:0:1004:1100:cfd0:d2ee:d54d:ab6d]) by smtp.gmail.com with ESMTPSA id c12sm55883402qka.42.2019.01.12.12.38.33 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 12 Jan 2019 12:38:34 -0800 (PST) From: Joel Fernandes To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , dancol@google.com, minchan@kernel.org, Jann Horn , John Stultz , Al Viro , Andrew Morton , Andy Lutomirski , Hugh Dickins , "J. Bruce Fields" , Jeff Layton , linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, =?utf-8?q?Marc-Andr=C3=A9_Lureau?= , Matthew Wilcox , Mike Kravetz , Shuah Khan Subject: [PATCH v4 2/2] selftests/memfd: Add tests for F_SEAL_FUTURE_WRITE seal Date: Sat, 12 Jan 2019 15:38:16 -0500 Message-Id: <20190112203816.85534-3-joel@joelfernandes.org> X-Mailer: git-send-email 2.20.1.97.g81188d93c3-goog In-Reply-To: <20190112203816.85534-1-joel@joelfernandes.org> References: <20190112203816.85534-1-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 From: "Joel Fernandes (Google)" Add tests to verify sealing memfds with the F_SEAL_FUTURE_WRITE works as expected. Cc: dancol@google.com Cc: minchan@kernel.org Cc: Jann Horn Cc: John Stultz Signed-off-by: Joel Fernandes (Google) Reviewed-by: Shuah Khan --- 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..c67d32eeb668 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -54,6 +54,22 @@ static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags) return fd; } +static int mfd_assert_reopen_fd(int fd_in) +{ + int r, fd; + char path[100]; + + sprintf(path, "/proc/self/fd/%d", fd_in); + + fd = open(path, O_RDWR); + if (fd < 0) { + printf("re-open of existing fd %d failed\n", fd_in); + abort(); + } + + return fd; +} + static void mfd_fail_new(const char *name, unsigned int flags) { int r; @@ -255,6 +271,25 @@ static void mfd_assert_read(int fd) munmap(p, mfd_def_size); } +/* Test that PROT_READ + MAP_SHARED mappings work. */ +static void mfd_assert_read_shared(int fd) +{ + void *p; + + /* verify PROT_READ and MAP_SHARED *is* allowed */ + p = mmap(NULL, + mfd_def_size, + PROT_READ, + MAP_SHARED, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + munmap(p, mfd_def_size); +} + static void mfd_assert_write(int fd) { ssize_t l; @@ -692,6 +727,44 @@ 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, fd2; + 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); + + mfd_assert_add_seals(fd, F_SEAL_FUTURE_WRITE); + mfd_assert_has_seals(fd, F_SEAL_FUTURE_WRITE); + + /* read should pass, writes should fail */ + mfd_assert_read(fd); + mfd_assert_read_shared(fd); + mfd_fail_write(fd); + + fd2 = mfd_assert_reopen_fd(fd); + /* read should pass, writes should still fail */ + mfd_assert_read(fd2); + mfd_assert_read_shared(fd2); + mfd_fail_write(fd2); + + munmap(p, mfd_def_size); + close(fd2); + 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();