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Tue, 21 Mar 2023 13:15:46 -0700 (PDT) Date: Tue, 21 Mar 2023 20:15:33 +0000 In-Reply-To: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.40.0.rc2.332.ga46443480c-goog Message-ID: <4db33a8976193f3eff80dbd4515335c36aeeb416.1679428901.git.ackerleytng@google.com> Subject: [RFC PATCH v2 2/2] selftests: restrictedmem: Check hugepage-ness of shmem file backing restrictedmem fd From: Ackerley Tng To: kvm@vger.kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, qemu-devel@nongnu.org Cc: aarcange@redhat.com, ak@linux.intel.com, akpm@linux-foundation.org, arnd@arndb.de, bfields@fieldses.org, bp@alien8.de, chao.p.peng@linux.intel.com, corbet@lwn.net, dave.hansen@intel.com, david@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, hpa@zytor.com, hughd@google.com, jlayton@kernel.org, jmattson@google.com, joro@8bytes.org, jun.nakajima@intel.com, kirill.shutemov@linux.intel.com, linmiaohe@huawei.com, luto@kernel.org, mail@maciej.szmigiero.name, mhocko@suse.com, michael.roth@amd.com, mingo@redhat.com, naoya.horiguchi@nec.com, pbonzini@redhat.com, qperret@google.com, rppt@kernel.org, seanjc@google.com, shuah@kernel.org, steven.price@arm.com, tabba@google.com, tglx@linutronix.de, vannapurve@google.com, vbabka@suse.cz, vkuznets@redhat.com, wanpengli@tencent.com, wei.w.wang@intel.com, x86@kernel.org, yu.c.zhang@linux.intel.com, Ackerley Tng X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 72D1118001B X-Stat-Signature: 4k1oby8g5s9u88tj8mzababchtjaxt61 X-HE-Tag: 1679429746-966959 X-HE-Meta: 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 6L0dfcxn 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 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: For memfd_restricted() calls without a userspace mount, the backing file should be the shmem mount in the kernel, and the size of backing pages should be as defined by system-wide shmem configuration. If a userspace mount is provided, the size of backing pages should be as defined in the mount. Signed-off-by: Ackerley Tng --- tools/testing/selftests/Makefile | 1 + .../selftests/restrictedmem/.gitignore | 3 + .../testing/selftests/restrictedmem/Makefile | 15 + .../testing/selftests/restrictedmem/common.c | 9 + .../testing/selftests/restrictedmem/common.h | 8 + .../restrictedmem_hugepage_test.c | 459 ++++++++++++++++++ 6 files changed, 495 insertions(+) create mode 100644 tools/testing/selftests/restrictedmem/.gitignore create mode 100644 tools/testing/selftests/restrictedmem/Makefile create mode 100644 tools/testing/selftests/restrictedmem/common.c create mode 100644 tools/testing/selftests/restrictedmem/common.h create mode 100644 tools/testing/selftests/restrictedmem/restrictedmem_hugepage_test.c diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index f07aef7c592c..44078eeefb79 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -60,6 +60,7 @@ TARGETS += pstore TARGETS += ptrace TARGETS += openat2 TARGETS += resctrl +TARGETS += restrictedmem TARGETS += rlimits TARGETS += rseq TARGETS += rtc diff --git a/tools/testing/selftests/restrictedmem/.gitignore b/tools/testing/selftests/restrictedmem/.gitignore new file mode 100644 index 000000000000..2581bcc8ff29 --- /dev/null +++ b/tools/testing/selftests/restrictedmem/.gitignore @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0-only + +restrictedmem_hugepage_test diff --git a/tools/testing/selftests/restrictedmem/Makefile b/tools/testing/selftests/restrictedmem/Makefile new file mode 100644 index 000000000000..8e5378d20226 --- /dev/null +++ b/tools/testing/selftests/restrictedmem/Makefile @@ -0,0 +1,15 @@ +# SPDX-License-Identifier: GPL-2.0 + +CFLAGS = $(KHDR_INCLUDES) +CFLAGS += -Wall -Wstrict-prototypes -Wuninitialized -std=gnu99 + +TEST_GEN_PROGS += restrictedmem_hugepage_test + +include ../lib.mk + +EXTRA_CLEAN = $(OUTPUT)/common.o + +$(OUTPUT)/common.o: common.c + $(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c -ffreestanding $< -o $@ + +$(TEST_GEN_PROGS): $(OUTPUT)/common.o diff --git a/tools/testing/selftests/restrictedmem/common.c b/tools/testing/selftests/restrictedmem/common.c new file mode 100644 index 000000000000..03dac843404f --- /dev/null +++ b/tools/testing/selftests/restrictedmem/common.c @@ -0,0 +1,9 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include +#include + +int memfd_restricted(unsigned int flags, int mount_fd) +{ + return syscall(__NR_memfd_restricted, flags, mount_fd); +} diff --git a/tools/testing/selftests/restrictedmem/common.h b/tools/testing/selftests/restrictedmem/common.h new file mode 100644 index 000000000000..06284ed86baf --- /dev/null +++ b/tools/testing/selftests/restrictedmem/common.h @@ -0,0 +1,8 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +#ifndef SELFTESTS_RESTRICTEDMEM_COMMON_H +#define SELFTESTS_RESTRICTEDMEM_COMMON_H + +int memfd_restricted(unsigned int flags, int mount_fd); + +#endif // SELFTESTS_RESTRICTEDMEM_COMMON_H diff --git a/tools/testing/selftests/restrictedmem/restrictedmem_hugepage_test.c b/tools/testing/selftests/restrictedmem/restrictedmem_hugepage_test.c new file mode 100644 index 000000000000..ae37148342fe --- /dev/null +++ b/tools/testing/selftests/restrictedmem/restrictedmem_hugepage_test.c @@ -0,0 +1,459 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#define _GNU_SOURCE /* for O_PATH */ +#define _POSIX_C_SOURCE /* for PATH_MAX */ +#include +#include +#include +#include +#include +#include +#include + +#include "linux/restrictedmem.h" + +#include "common.h" +#include "../kselftest_harness.h" + +/* + * Expect policy to be one of always, within_size, advise, never, + * deny, force + */ +#define POLICY_BUF_SIZE 12 + +static int get_hpage_pmd_size(void) +{ + FILE *fp; + char buf[100]; + char *ret; + int size; + + fp = fopen("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size", "r"); + if (!fp) + return -1; + + ret = fgets(buf, 100, fp); + if (ret != buf) { + size = -1; + goto out; + } + + if (sscanf(buf, "%d\n", &size) != 1) + size = -1; + +out: + fclose(fp); + + return size; +} + +static bool is_valid_shmem_thp_policy(char *policy) +{ + if (strcmp(policy, "always") == 0) + return true; + if (strcmp(policy, "within_size") == 0) + return true; + if (strcmp(policy, "advise") == 0) + return true; + if (strcmp(policy, "never") == 0) + return true; + if (strcmp(policy, "deny") == 0) + return true; + if (strcmp(policy, "force") == 0) + return true; + + return false; +} + +static int get_shmem_thp_policy(char *policy) +{ + FILE *fp; + char buf[100]; + char *left = NULL; + char *right = NULL; + int ret = -1; + + fp = fopen("/sys/kernel/mm/transparent_hugepage/shmem_enabled", "r"); + if (!fp) + return -1; + + if (fgets(buf, 100, fp) != buf) + goto out; + + /* + * Expect shmem_enabled to be of format like "always within_size advise + * [never] deny force" + */ + left = memchr(buf, '[', 100); + if (!left) + goto out; + + right = memchr(buf, ']', 100); + if (!right) + goto out; + + memcpy(policy, left + 1, right - left - 1); + + ret = !is_valid_shmem_thp_policy(policy); + +out: + fclose(fp); + return ret; +} + +static int write_string_to_file(const char *path, const char *string) +{ + FILE *fp; + size_t len = strlen(string); + int ret = -1; + + fp = fopen(path, "w"); + if (!fp) + return ret; + + if (fwrite(string, 1, len, fp) != len) + goto out; + + ret = 0; + +out: + fclose(fp); + return ret; +} + +static int set_shmem_thp_policy(char *policy) +{ + int ret = -1; + /* +1 for newline */ + char to_write[POLICY_BUF_SIZE + 1] = { 0 }; + + if (!is_valid_shmem_thp_policy(policy)) + return ret; + + ret = snprintf(to_write, POLICY_BUF_SIZE + 1, "%s\n", policy); + if (ret != strlen(policy) + 1) + return -1; + + ret = write_string_to_file( + "/sys/kernel/mm/transparent_hugepage/shmem_enabled", to_write); + + return ret; +} + +FIXTURE(reset_shmem_enabled) +{ + char shmem_enabled[POLICY_BUF_SIZE]; +}; + +FIXTURE_SETUP(reset_shmem_enabled) +{ + memset(self->shmem_enabled, 0, POLICY_BUF_SIZE); + ASSERT_EQ(0, get_shmem_thp_policy(self->shmem_enabled)); +} + +FIXTURE_TEARDOWN(reset_shmem_enabled) +{ + ASSERT_EQ(0, set_shmem_thp_policy(self->shmem_enabled)); +} + +TEST_F(reset_shmem_enabled, restrictedmem_fstat_shmem_enabled_never) +{ + int fd = -1; + struct stat stat; + + ASSERT_EQ(0, set_shmem_thp_policy("never")); + + fd = memfd_restricted(0, -1); + ASSERT_NE(-1, fd); + + ASSERT_EQ(0, fstat(fd, &stat)); + + /* + * st_blksize is set based on the superblock's s_blocksize_bits. For + * shmem, this is set to PAGE_SHIFT + */ + ASSERT_EQ(stat.st_blksize, getpagesize()); + + close(fd); +} + +TEST_F(reset_shmem_enabled, restrictedmem_fstat_shmem_enabled_always) +{ + int fd = -1; + struct stat stat; + + ASSERT_EQ(0, set_shmem_thp_policy("always")); + + fd = memfd_restricted(0, -1); + ASSERT_NE(-1, fd); + + ASSERT_EQ(0, fstat(fd, &stat)); + + ASSERT_EQ(stat.st_blksize, get_hpage_pmd_size()); + + close(fd); +} + +TEST(restrictedmem_tmpfile_invalid_fd) +{ + int fd = memfd_restricted(RMFD_TMPFILE, -2); + + ASSERT_EQ(-1, fd); + ASSERT_EQ(EINVAL, errno); +} + +TEST(restrictedmem_tmpfile_fd_not_a_mount) +{ + int fd = memfd_restricted(RMFD_TMPFILE, STDOUT_FILENO); + + ASSERT_EQ(-1, fd); + ASSERT_EQ(EINVAL, errno); +} + +TEST(restrictedmem_tmpfile_not_tmpfs_mount) +{ + int fd = -1; + int mfd = -1; + + mfd = open("/proc", O_PATH); + ASSERT_NE(-1, mfd); + + fd = memfd_restricted(RMFD_TMPFILE, mfd); + + ASSERT_EQ(-1, fd); + ASSERT_EQ(EINVAL, errno); +} + +FIXTURE(tmpfs_hugepage_sfd) +{ + int sfd; +}; + +FIXTURE_SETUP(tmpfs_hugepage_sfd) +{ + self->sfd = fsopen("tmpfs", 0); + ASSERT_NE(-1, self->sfd); +} + +FIXTURE_TEARDOWN(tmpfs_hugepage_sfd) +{ + close(self->sfd); +} + +TEST_F(tmpfs_hugepage_sfd, restrictedmem_fstat_tmpfs_huge_always) +{ + int ret = -1; + int fd = -1; + int mfd = -1; + struct stat stat; + + fsconfig(self->sfd, FSCONFIG_SET_STRING, "huge", "always", 0); + fsconfig(self->sfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0); + + mfd = fsmount(self->sfd, 0, 0); + ASSERT_NE(-1, mfd); + + fd = memfd_restricted(RMFD_TMPFILE, mfd); + ASSERT_NE(-1, fd); + + /* User can close reference to mount */ + ret = close(mfd); + ASSERT_EQ(0, ret); + + ret = fstat(fd, &stat); + ASSERT_EQ(0, ret); + ASSERT_EQ(stat.st_blksize, get_hpage_pmd_size()); + + close(fd); +} + +TEST_F(tmpfs_hugepage_sfd, restrictedmem_fstat_tmpfs_huge_never) +{ + int ret = -1; + int fd = -1; + int mfd = -1; + struct stat stat; + + fsconfig(self->sfd, FSCONFIG_SET_STRING, "huge", "never", 0); + fsconfig(self->sfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0); + + mfd = fsmount(self->sfd, 0, 0); + ASSERT_NE(-1, mfd); + + fd = memfd_restricted(RMFD_TMPFILE, mfd); + ASSERT_NE(-1, fd); + + /* User can close reference to mount */ + ret = close(mfd); + ASSERT_EQ(0, ret); + + ret = fstat(fd, &stat); + ASSERT_EQ(0, ret); + ASSERT_EQ(stat.st_blksize, getpagesize()); + + close(fd); +} + +static bool directory_exists(const char *path) +{ + struct stat sb; + + return stat(path, &sb) == 0 && S_ISDIR(sb.st_mode); +} + +FIXTURE(tmpfs_hugepage_mount_path) +{ + char *mount_path; +}; + +FIXTURE_SETUP(tmpfs_hugepage_mount_path) +{ + int ret = -1; + + /* /tmp is an FHS-mandated world-writable directory */ + self->mount_path = "/tmp/restrictedmem-selftest-mnt"; + + if (!directory_exists(self->mount_path)) { + ret = mkdir(self->mount_path, 0777); + ASSERT_EQ(0, ret); + } +} + +FIXTURE_TEARDOWN(tmpfs_hugepage_mount_path) +{ + int ret = -1; + + if (!directory_exists(self->mount_path)) + return; + + ret = umount2(self->mount_path, MNT_FORCE); + EXPECT_EQ(0, ret); + if (ret == -1 && errno == EINVAL) + fprintf(stderr, "%s was not mounted\n", self->mount_path); + + ret = rmdir(self->mount_path); + EXPECT_EQ(0, ret); + if (ret == -1) + fprintf(stderr, "rmdir(%s) failed\n", self->mount_path); +} + +/* + * When the restrictedmem's fd is open, a user should not be able to unmount or + * remove the mounted directory + */ +TEST_F(tmpfs_hugepage_mount_path, restrictedmem_umount_rmdir_while_file_open) +{ + int ret = -1; + int fd = -1; + int mfd = -1; + struct stat stat; + + ret = mount("name", self->mount_path, "tmpfs", 0, "huge=always"); + ASSERT_EQ(0, ret); + + mfd = open(self->mount_path, O_PATH); + ASSERT_NE(-1, mfd); + + fd = memfd_restricted(RMFD_TMPFILE, mfd); + ASSERT_NE(-1, fd); + + /* We don't need this reference to the mount anymore */ + ret = close(mfd); + ASSERT_EQ(0, ret); + + /* restrictedmem's fd should still be usable */ + ret = fstat(fd, &stat); + ASSERT_EQ(0, ret); + ASSERT_EQ(stat.st_blksize, get_hpage_pmd_size()); + + /* User should not be able to unmount directory */ + ret = umount2(self->mount_path, MNT_FORCE); + ASSERT_EQ(-1, ret); + ASSERT_EQ(EBUSY, errno); + + ret = rmdir(self->mount_path); + ASSERT_EQ(-1, ret); + ASSERT_EQ(EBUSY, errno); + + close(fd); +} + +/* The fd of a file on the mount can be provided as mount_fd */ +TEST_F(tmpfs_hugepage_mount_path, restrictedmem_provide_fd_of_file) +{ + int ret = -1; + int fd = -1; + int ffd = -1; + char tmp_file_path[PATH_MAX] = { 0 }; + struct stat stat; + + ret = mount("name", self->mount_path, "tmpfs", 0, "huge=always"); + ASSERT_EQ(0, ret); + + snprintf(tmp_file_path, PATH_MAX, "%s/tmp-file", self->mount_path); + ret = write_string_to_file(tmp_file_path, "filler\n"); + ASSERT_EQ(0, ret); + + ffd = open(tmp_file_path, O_RDWR); + ASSERT_NE(-1, ffd); + + fd = memfd_restricted(RMFD_TMPFILE, ffd); + ASSERT_NE(-1, fd); + + /* We don't need this reference anymore */ + ret = close(ffd); + ASSERT_EQ(0, ret); + + ret = fstat(fd, &stat); + ASSERT_EQ(0, ret); + ASSERT_EQ(stat.st_blksize, get_hpage_pmd_size()); + + close(fd); + remove(tmp_file_path); +} + +/* + * The fd of any file on the mount (including subdirectories) can be provided as + * mount_fd + */ +TEST_F(tmpfs_hugepage_mount_path, restrictedmem_provide_fd_of_file_in_subdir) +{ + int ret = -1; + int fd = -1; + int ffd = -1; + char tmp_dir_path[PATH_MAX] = { 0 }; + char tmp_file_path[PATH_MAX] = { 0 }; + struct stat stat; + + ret = mount("name", self->mount_path, "tmpfs", 0, "huge=always"); + ASSERT_EQ(0, ret); + + snprintf(tmp_dir_path, PATH_MAX, "%s/tmp-subdir", self->mount_path); + ret = mkdir(tmp_dir_path, 0777); + ASSERT_EQ(0, ret); + + snprintf(tmp_file_path, PATH_MAX, "%s/tmp-subdir/tmp-file", + self->mount_path); + ret = write_string_to_file(tmp_file_path, "filler\n"); + ASSERT_EQ(0, ret); + + ffd = open(tmp_file_path, O_RDWR); + ASSERT_NE(-1, ffd); + + fd = memfd_restricted(RMFD_TMPFILE, ffd); + ASSERT_NE(-1, fd); + + /* We don't need this reference anymore */ + ret = close(ffd); + ASSERT_EQ(0, ret); + + ret = fstat(fd, &stat); + ASSERT_EQ(0, ret); + ASSERT_EQ(stat.st_blksize, get_hpage_pmd_size()); + + close(fd); + remove(tmp_file_path); + rmdir(tmp_dir_path); +} + +TEST_HARNESS_MAIN