Re: [PATCH v9 11/11] LSM: selftests for Linux Security Module syscalls

Casey Schaufler
2023-04-27T16:00:48Z

On 4/21/2023 1:01 PM, Kees Cook wrote:
> On Fri, Apr 21, 2023 at 10:42:59AM -0700, Casey Schaufler wrote:
>> Add selftests for the three system calls supporting the LSM
>> infrastructure.
> Yay tests!
>
> With nits below fixed:
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>> ---
>> tools/testing/selftests/Makefile | 1 +
>> tools/testing/selftests/lsm/Makefile | 12 +
>> tools/testing/selftests/lsm/config | 2 +
>> .../selftests/lsm/lsm_get_self_attr_test.c | 267 ++++++++++++++++++
>> .../selftests/lsm/lsm_list_modules_test.c | 149 ++++++++++
>> .../selftests/lsm/lsm_set_self_attr_test.c | 70 +++++
>> 6 files changed, 501 insertions(+)
>> create mode 100644 tools/testing/selftests/lsm/Makefile
>> create mode 100644 tools/testing/selftests/lsm/config
>> create mode 100644 tools/testing/selftests/lsm/lsm_get_self_attr_test.c
>> create mode 100644 tools/testing/selftests/lsm/lsm_list_modules_test.c
>> create mode 100644 tools/testing/selftests/lsm/lsm_set_self_attr_test.c
>>
>> diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
>> index 13a6837a0c6b..b18d133a1141 100644
>> --- a/tools/testing/selftests/Makefile
>> +++ b/tools/testing/selftests/Makefile
>> @@ -38,6 +38,7 @@ TARGETS += landlock
>> TARGETS += lib
>> TARGETS += livepatch
>> TARGETS += lkdtm
>> +TARGETS += lsm
>> TARGETS += membarrier
>> TARGETS += memfd
>> TARGETS += memory-hotplug
>> diff --git a/tools/testing/selftests/lsm/Makefile b/tools/testing/selftests/lsm/Makefile
>> new file mode 100644
>> index 000000000000..f39a75212b78
>> --- /dev/null
>> +++ b/tools/testing/selftests/lsm/Makefile
>> @@ -0,0 +1,12 @@
>> +# SPDX-License-Identifier: GPL-2.0
>> +#
>> +# First run: make -C ../../../.. headers_install
>> +
>> +CFLAGS += -Wall -O2 $(KHDR_INCLUDES)
>> +
>> +TEST_GEN_PROGS := lsm_get_self_attr_test lsm_list_modules_test \
>> + lsm_set_self_attr_test
>> +
>> +include ../lib.mk
>> +
>> +$(TEST_GEN_PROGS):
>> diff --git a/tools/testing/selftests/lsm/config b/tools/testing/selftests/lsm/config
>> new file mode 100644
>> index 000000000000..afb887715f64
>> --- /dev/null
>> +++ b/tools/testing/selftests/lsm/config
>> @@ -0,0 +1,2 @@
>> +CONFIG_SYSFS=y
>> +CONFIG_SECURITY=y
>> diff --git a/tools/testing/selftests/lsm/lsm_get_self_attr_test.c b/tools/testing/selftests/lsm/lsm_get_self_attr_test.c
>> new file mode 100644
>> index 000000000000..71c2b1a8a44e
>> --- /dev/null
>> +++ b/tools/testing/selftests/lsm/lsm_get_self_attr_test.c
>> @@ -0,0 +1,267 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Linux Security Module infrastructure tests
>> + * Tests for the lsm_get_self_attr system call
>> + *
>> + * Copyright © 2022 Casey Schaufler <casey@schaufler-ca.com>
>> + * Copyright © 2022 Intel Corporation
>> + */
>> +
>> +#define _GNU_SOURCE
>> +#include <linux/lsm.h>
>> +#include <fcntl.h>
>> +#include <string.h>
>> +#include <stdio.h>
>> +#include <unistd.h>
>> +#include <sys/types.h>
>> +#include "../kselftest_harness.h"
>> +
>> +#define PROCATTR "/proc/self/attr/"
>> +
>> +static int read_proc_attr(const char *attr, char *value, __kernel_size_t size)
>> +{
>> + int fd;
>> + int len;
>> + char *path;
>> +
>> + len = strlen(PROCATTR) + strlen(attr) + 1;
>> + path = calloc(len, 1);
>> + if (path == NULL)
>> + return -1;
>> + sprintf(path, "%s%s", PROCATTR, attr);
>> +
>> + fd = open(path, O_RDONLY);
>> + free(path);
>> +
>> + if (fd < 0)
>> + return -1;
>> + len = read(fd, value, size);
>> + if (len <= 0)
>> + return -1;
>> +fprintf(stderr, "len=%d\n", len);
> Accidentally leftover debugging?

Yup.

>> + close(fd);
>> +
>> + path = strchr(value, '\n');
>> + if (path)
>> + *path = '\0';
>> +
>> + return 0;
>> +}
>> +
>> +static struct lsm_ctx *next_ctx(struct lsm_ctx *ctxp)
>> +{
>> + void *vp;
>> +
>> + vp = (void *)ctxp + sizeof(*ctxp) + ctxp->ctx_len;
>> + return (struct lsm_ctx *)vp;
>> +}
>> +
>> +TEST(size_null_lsm_get_self_attr)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + char *ctx = calloc(page_size, 1);
>> +
>> + ASSERT_NE(NULL, ctx);
>> + ASSERT_EQ(-1, syscall(__NR_lsm_get_self_attr, LSM_ATTR_CURRENT, ctx,
>> + NULL, 0));
>> + ASSERT_EQ(EINVAL, errno);
>> +
>> + free(ctx);
>> +}
>> +
>> +TEST(ctx_null_lsm_get_self_attr)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + __kernel_size_t size = page_size;
>> +
>> + ASSERT_NE(-1, syscall(__NR_lsm_get_self_attr, LSM_ATTR_CURRENT, NULL,
>> + &size, 0));
>> + ASSERT_NE(1, size);
>> +}
>> +
>> +TEST(size_too_small_lsm_get_self_attr)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + char *ctx = calloc(page_size, 1);
>> + __kernel_size_t size = 1;
>> +
>> + ASSERT_NE(NULL, ctx);
>> + ASSERT_EQ(-1, syscall(__NR_lsm_get_self_attr, LSM_ATTR_CURRENT, ctx,
>> + &size, 0));
>> + ASSERT_EQ(E2BIG, errno);
>> + ASSERT_NE(1, size);
>> +
>> + free(ctx);
>> +}
>> +
>> +TEST(flags_zero_lsm_get_self_attr)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + char *ctx = calloc(page_size, 1);
>> + __kernel_size_t size = page_size;
>> +
>> + ASSERT_NE(NULL, ctx);
> I would explicitly set errno to 0 before syscalls, just to sure.

Good idea for the cases where errno gets checked.

>> + ASSERT_EQ(-1, syscall(__NR_lsm_get_self_attr, LSM_ATTR_CURRENT, ctx,
>> + &size, 1));
>> + ASSERT_EQ(EINVAL, errno);
>> + ASSERT_EQ(page_size, size);
>> +
>> + free(ctx);
>> +}
>> +
>> +TEST(flags_overset_lsm_get_self_attr)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + char *ctx = calloc(page_size, 1);
>> + __kernel_size_t size = page_size;
>> +
>> + ASSERT_NE(NULL, ctx);
> e.g.:
> errno = 0;
>
> but repeated for all syscalls below...
>
>> + ASSERT_EQ(-1, syscall(__NR_lsm_get_self_attr,
>> + LSM_ATTR_CURRENT | LSM_ATTR_PREV, ctx, &size, 0));
>> + ASSERT_EQ(EOPNOTSUPP, errno);
>> +
>> + free(ctx);
>> +}
>> +
>> +TEST(basic_lsm_get_self_attr)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + __kernel_size_t size = page_size;
>> + struct lsm_ctx *ctx = calloc(page_size, 1);
>> + struct lsm_ctx *tctx = NULL;
>> + __u64 *syscall_lsms = calloc(page_size, 1);
>> + char *attr = calloc(page_size, 1);
>> + int cnt_current = 0;
>> + int cnt_exec = 0;
>> + int cnt_fscreate = 0;
>> + int cnt_keycreate = 0;
>> + int cnt_prev = 0;
>> + int cnt_sockcreate = 0;
>> + int lsmcount;
>> + int count;
>> + int i;
>> +
>> + ASSERT_NE(NULL, ctx);
>> + ASSERT_NE(NULL, syscall_lsms);
>> +
>> + lsmcount = syscall(__NR_lsm_list_modules, syscall_lsms, &size, 0);
>> + ASSERT_LE(1, lsmcount);
>> +
>> + for (i = 0; i < lsmcount; i++) {
>> + switch (syscall_lsms[i]) {
>> + case LSM_ID_SELINUX:
>> + cnt_current++;
>> + cnt_exec++;
>> + cnt_fscreate++;
>> + cnt_keycreate++;
>> + cnt_prev++;
>> + cnt_sockcreate++;
>> + break;
>> + case LSM_ID_SMACK:
>> + cnt_current++;
>> + break;
>> + case LSM_ID_APPARMOR:
>> + cnt_current++;
>> + cnt_exec++;
>> + cnt_prev++;
>> + break;
>> + default:
>> + break;
>> + }
>> + }
>> +
>> + if (cnt_current) {
>> + size = page_size;
>> + count = syscall(__NR_lsm_get_self_attr, LSM_ATTR_CURRENT, ctx,
>> + &size, 0);
>> + ASSERT_EQ(cnt_current, count);
>> + tctx = ctx;
>> + ASSERT_EQ(0, read_proc_attr("current", attr, page_size));
>> + ASSERT_EQ(0, strcmp((char *)tctx->ctx, attr));
>> + for (i = 1; i < count; i++) {
>> + tctx = next_ctx(tctx);
>> + ASSERT_NE(0, strcmp((char *)tctx->ctx, attr));
>> + }
>> + }
>> + if (cnt_exec) {
>> + size = page_size;
>> + count = syscall(__NR_lsm_get_self_attr, LSM_ATTR_EXEC, ctx,
>> + &size, 0);
>> + ASSERT_GE(cnt_exec, count);
>> + if (count > 0) {
>> + tctx = ctx;
>> + if (read_proc_attr("exec", attr, page_size) == 0)
>> + ASSERT_EQ(0, strcmp((char *)tctx->ctx, attr));
>> + }
>> + for (i = 1; i < count; i++) {
>> + tctx = next_ctx(tctx);
>> + ASSERT_NE(0, strcmp((char *)tctx->ctx, attr));
>> + }
>> + }
>> + if (cnt_fscreate) {
>> + size = page_size;
>> + count = syscall(__NR_lsm_get_self_attr, LSM_ATTR_FSCREATE, ctx,
>> + &size, 0);
>> + ASSERT_GE(cnt_fscreate, count);
>> + if (count > 0) {
>> + tctx = ctx;
>> + if (read_proc_attr("fscreate", attr, page_size) == 0)
>> + ASSERT_EQ(0, strcmp((char *)tctx->ctx, attr));
>> + }
>> + for (i = 1; i < count; i++) {
>> + tctx = next_ctx(tctx);
>> + ASSERT_NE(0, strcmp((char *)tctx->ctx, attr));
>> + }
>> + }
>> + if (cnt_keycreate) {
>> + size = page_size;
>> + count = syscall(__NR_lsm_get_self_attr, LSM_ATTR_KEYCREATE, ctx,
>> + &size, 0);
>> + ASSERT_GE(cnt_keycreate, count);
>> + if (count > 0) {
>> + tctx = ctx;
>> + if (read_proc_attr("keycreate", attr, page_size) == 0)
>> + ASSERT_EQ(0, strcmp((char *)tctx->ctx, attr));
>> + }
>> + for (i = 1; i < count; i++) {
>> + tctx = next_ctx(tctx);
>> + ASSERT_NE(0, strcmp((char *)tctx->ctx, attr));
>> + }
>> + }
>> + if (cnt_prev) {
>> + size = page_size;
>> + count = syscall(__NR_lsm_get_self_attr, LSM_ATTR_PREV, ctx,
>> + &size, 0);
>> + ASSERT_GE(cnt_prev, count);
>> + if (count > 0) {
>> + tctx = ctx;
>> + ASSERT_EQ(0, read_proc_attr("prev", attr, page_size));
>> + ASSERT_EQ(0, strcmp((char *)tctx->ctx, attr));
>> + for (i = 1; i < count; i++) {
>> + tctx = next_ctx(tctx);
>> + ASSERT_NE(0, strcmp((char *)tctx->ctx, attr));
>> + }
>> + }
>> + }
>> + if (cnt_sockcreate) {
>> + size = page_size;
>> + count = syscall(__NR_lsm_get_self_attr, LSM_ATTR_SOCKCREATE,
>> + ctx, &size, 0);
>> + ASSERT_GE(cnt_sockcreate, count);
>> + if (count > 0) {
>> + tctx = ctx;
>> + if (read_proc_attr("sockcreate", attr, page_size) == 0)
>> + ASSERT_EQ(0, strcmp((char *)tctx->ctx, attr));
>> + }
>> + for (i = 1; i < count; i++) {
>> + tctx = next_ctx(tctx);
>> + ASSERT_NE(0, strcmp((char *)tctx->ctx, attr));
>> + }
>> + }
>> +
>> + free(ctx);
>> + free(attr);
>> + free(syscall_lsms);
>> +}
>> +
>> +TEST_HARNESS_MAIN
>> diff --git a/tools/testing/selftests/lsm/lsm_list_modules_test.c b/tools/testing/selftests/lsm/lsm_list_modules_test.c
>> new file mode 100644
>> index 000000000000..3ec814002710
>> --- /dev/null
>> +++ b/tools/testing/selftests/lsm/lsm_list_modules_test.c
>> @@ -0,0 +1,149 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Linux Security Module infrastructure tests
>> + * Tests for the lsm_list_modules system call
>> + *
>> + * Copyright © 2022 Casey Schaufler <casey@schaufler-ca.com>
>> + * Copyright © 2022 Intel Corporation
>> + */
>> +
>> +#define _GNU_SOURCE
>> +#include <linux/lsm.h>
>> +#include <string.h>
>> +#include <stdio.h>
>> +#include <unistd.h>
>> +#include <sys/types.h>
>> +#include "../kselftest_harness.h"
>> +
>> +static int read_sysfs_lsms(char *lsms, __kernel_size_t size)
>> +{
>> + FILE *fp;
>> +
>> + fp = fopen("/sys/kernel/security/lsm", "r");
>> + if (fp == NULL)
>> + return -1;
>> + if (fread(lsms, 1, size, fp) <= 0)
>> + return -1;
>> + fclose(fp);
>> + return 0;
>> +}
>> +
>> +TEST(size_null_lsm_list_modules)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + char *syscall_lsms = calloc(page_size, 1);
>> +
>> + ASSERT_NE(NULL, syscall_lsms);
>> + ASSERT_EQ(-1, syscall(__NR_lsm_list_modules, syscall_lsms, NULL, 0));
>> + ASSERT_EQ(EFAULT, errno);
>> +
>> + free(syscall_lsms);
>> +}
>> +
>> +TEST(ids_null_lsm_list_modules)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + __kernel_size_t size = page_size;
>> +
>> + ASSERT_EQ(-1, syscall(__NR_lsm_list_modules, NULL, &size, 0));
>> + ASSERT_EQ(EFAULT, errno);
>> + ASSERT_NE(1, size);
>> +}
>> +
>> +TEST(size_too_small_lsm_list_modules)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + char *syscall_lsms = calloc(page_size, 1);
>> + __kernel_size_t size = 1;
>> +
>> + ASSERT_NE(NULL, syscall_lsms);
>> + ASSERT_EQ(-1, syscall(__NR_lsm_list_modules, syscall_lsms, &size, 0));
>> + ASSERT_EQ(E2BIG, errno);
>> + ASSERT_NE(1, size);
>> +
>> + free(syscall_lsms);
>> +}
>> +
>> +TEST(flags_set_lsm_list_modules)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + char *syscall_lsms = calloc(page_size, 1);
>> + __kernel_size_t size = page_size;
>> +
>> + ASSERT_NE(NULL, syscall_lsms);
>> + ASSERT_EQ(-1, syscall(__NR_lsm_list_modules, syscall_lsms, &size, 7));
>> + ASSERT_EQ(EINVAL, errno);
>> + ASSERT_EQ(page_size, size);
>> +
>> + free(syscall_lsms);
>> +}
>> +
>> +TEST(correct_lsm_list_modules)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + __kernel_size_t size = page_size;
>> + __u64 *syscall_lsms = calloc(page_size, 1);
>> + char *sysfs_lsms = calloc(page_size, 1);
>> + char *name;
>> + char *cp;
>> + int count;
>> + int i;
>> +
>> + ASSERT_NE(NULL, sysfs_lsms);
>> + ASSERT_NE(NULL, syscall_lsms);
>> + ASSERT_EQ(0, read_sysfs_lsms(sysfs_lsms, page_size));
>> +
>> + count = syscall(__NR_lsm_list_modules, syscall_lsms, &size, 0);
>> + ASSERT_LE(1, count);
>> + cp = sysfs_lsms;
>> + for (i = 0; i < count; i++) {
>> + switch (syscall_lsms[i]) {
>> + case LSM_ID_CAPABILITY:
>> + name = "capability";
>> + break;
>> + case LSM_ID_SELINUX:
>> + name = "selinux";
>> + break;
>> + case LSM_ID_SMACK:
>> + name = "smack";
>> + break;
>> + case LSM_ID_TOMOYO:
>> + name = "tomoyo";
>> + break;
>> + case LSM_ID_IMA:
>> + name = "ima";
>> + break;
>> + case LSM_ID_APPARMOR:
>> + name = "apparmor";
>> + break;
>> + case LSM_ID_YAMA:
>> + name = "yama";
>> + break;
>> + case LSM_ID_LOADPIN:
>> + name = "loadpin";
>> + break;
>> + case LSM_ID_SAFESETID:
>> + name = "safesetid";
>> + break;
>> + case LSM_ID_LOCKDOWN:
>> + name = "lockdown";
>> + break;
>> + case LSM_ID_BPF:
>> + name = "bpf";
>> + break;
>> + case LSM_ID_LANDLOCK:
>> + name = "landlock";
>> + break;
>> + default:
>> + name = "INVALID";
>> + break;
>> + }
>> + ASSERT_EQ(0, strncmp(cp, name, strlen(name)));
>> + cp += strlen(name) + 1;
>> + }
>> +
>> + free(sysfs_lsms);
>> + free(syscall_lsms);
>> +}
>> +
>> +TEST_HARNESS_MAIN
>> diff --git a/tools/testing/selftests/lsm/lsm_set_self_attr_test.c b/tools/testing/selftests/lsm/lsm_set_self_attr_test.c
>> new file mode 100644
>> index 000000000000..ca538a703168
>> --- /dev/null
>> +++ b/tools/testing/selftests/lsm/lsm_set_self_attr_test.c
>> @@ -0,0 +1,70 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Linux Security Module infrastructure tests
>> + * Tests for the lsm_set_self_attr system call
>> + *
>> + * Copyright © 2022 Casey Schaufler <casey@schaufler-ca.com>
>> + * Copyright © 2022 Intel Corporation
>> + */
>> +
>> +#define _GNU_SOURCE
>> +#include <linux/lsm.h>
>> +#include <string.h>
>> +#include <stdio.h>
>> +#include <unistd.h>
>> +#include <sys/types.h>
>> +#include "../kselftest_harness.h"
>> +
>> +TEST(ctx_null_lsm_set_self_attr)
>> +{
>> + ASSERT_EQ(-1, syscall(__NR_lsm_set_self_attr, LSM_ATTR_CURRENT, NULL,
>> + sizeof(struct lsm_ctx), 0));
>> +}
>> +
>> +TEST(size_too_small_lsm_set_self_attr)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + struct lsm_ctx *ctx = calloc(page_size, 1);
>> + __kernel_size_t size = page_size;
>> +
>> + ASSERT_NE(NULL, ctx);
>> + ASSERT_GE(1, syscall(__NR_lsm_get_self_attr, LSM_ATTR_CURRENT, ctx,
>> + &size, 0));
>> + ASSERT_EQ(-1, syscall(__NR_lsm_set_self_attr, LSM_ATTR_CURRENT, ctx, 1,
>> + 0));
>> +
>> + free(ctx);
>> +}
>> +
>> +TEST(flags_zero_lsm_set_self_attr)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + char *ctx = calloc(page_size, 1);
>> + __kernel_size_t size = page_size;
>> +
>> + ASSERT_NE(NULL, ctx);
>> + ASSERT_GE(1, syscall(__NR_lsm_get_self_attr, LSM_ATTR_CURRENT, ctx,
>> + &size, 0));
>> + ASSERT_EQ(-1, syscall(__NR_lsm_set_self_attr, LSM_ATTR_CURRENT, ctx,
>> + size, 1));
>> +
>> + free(ctx);
>> +}
>> +
>> +TEST(flags_overset_lsm_set_self_attr)
>> +{
>> + const long page_size = sysconf(_SC_PAGESIZE);
>> + char *ctx = calloc(page_size, 1);
>> + __kernel_size_t size = page_size;
>> + struct lsm_ctx *tctx = (struct lsm_ctx *)ctx;
>> +
>> + ASSERT_NE(NULL, ctx);
>> + ASSERT_GE(1, syscall(__NR_lsm_get_self_attr, LSM_ATTR_CURRENT, tctx,
>> + &size, 0));
>> + ASSERT_EQ(-1, syscall(__NR_lsm_set_self_attr,
>> + LSM_ATTR_CURRENT | LSM_ATTR_PREV, tctx, size, 0));
>> +
>> + free(ctx);
>> +}
>> +
>> +TEST_HARNESS_MAIN
>> --
>> 2.39.2
>>