[LTP] [PATCH v2 05/11] Add landlock01 test
Andrea Cervesato
andrea.cervesato@suse.com
Thu Jul 11 09:06:45 CEST 2024
Hi,
On 7/11/24 05:16, Li Wang wrote:
> Hi Andrea,
>
> On Thu, Jul 11, 2024 at 2:02 AM Andrea Cervesato
> <andrea.cervesato@suse.de> wrote:
>
> From: Andrea Cervesato <andrea.cervesato@suse.com>
>
> This test verifies that landlock_create_ruleset syscall fails with the
> right error codes:
>
> - EINVAL Unknown flags, or unknown access, or too small size
> - E2BIG size is too big
> - EFAULT attr was not a valid address
> - ENOMSG Empty accesses (i.e., attr->handled_access_fs is 0)
>
> Reviewed-by: Li Wang <liwang@redhat.com>
> Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
> ---
> runtest/syscalls | 2 +
> testcases/kernel/syscalls/landlock/.gitignore | 1 +
> testcases/kernel/syscalls/landlock/Makefile | 7 ++
> testcases/kernel/syscalls/landlock/landlock01.c | 92
> ++++++++++++++++++++++
> .../kernel/syscalls/landlock/landlock_common.h | 74
> +++++++++++++++++
> 5 files changed, 176 insertions(+)
>
> diff --git a/runtest/syscalls b/runtest/syscalls
> index b6cadb2df..667e419a3 100644
> --- a/runtest/syscalls
> +++ b/runtest/syscalls
> @@ -684,6 +684,8 @@ kill11 kill11
> kill12 kill12
> kill13 kill13
>
> +landlock01 landlock01
> +
> lchown01 lchown01
> lchown01_16 lchown01_16
> lchown02 lchown02
> diff --git a/testcases/kernel/syscalls/landlock/.gitignore
> b/testcases/kernel/syscalls/landlock/.gitignore
> new file mode 100644
> index 000000000..b69f9b94a
> --- /dev/null
> +++ b/testcases/kernel/syscalls/landlock/.gitignore
> @@ -0,0 +1 @@
> +landlock01
> diff --git a/testcases/kernel/syscalls/landlock/Makefile
> b/testcases/kernel/syscalls/landlock/Makefile
> new file mode 100644
> index 000000000..8cf1b9024
> --- /dev/null
> +++ b/testcases/kernel/syscalls/landlock/Makefile
> @@ -0,0 +1,7 @@
> +# SPDX-License-Identifier: GPL-2.0-or-later
> +# Copyright (C) 2024 SUSE LLC Andrea Cervesato
> <andrea.cervesato@suse.com>
> +
> +top_srcdir ?= ../../../..
> +
> +include $(top_srcdir)/include/mk/testcases.mk <http://testcases.mk>
> +include $(top_srcdir)/include/mk/generic_leaf_target.mk
> <http://generic_leaf_target.mk>
> diff --git a/testcases/kernel/syscalls/landlock/landlock01.c
> b/testcases/kernel/syscalls/landlock/landlock01.c
> new file mode 100644
> index 000000000..90f338fb0
> --- /dev/null
> +++ b/testcases/kernel/syscalls/landlock/landlock01.c
> @@ -0,0 +1,92 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2024 SUSE LLC Andrea Cervesato
> <andrea.cervesato@suse.com>
> + */
> +
> +/*\
> + * [Description]
> + *
> + * This test verifies that landlock_create_ruleset syscall fails
> with the right
> + * error codes:
> + *
> + * - EINVAL Unknown flags, or unknown access, or too small size
> + * - E2BIG size is too big
> + * - EFAULT attr was not a valid address
> + * - ENOMSG Empty accesses (i.e., attr->handled_access_fs is 0)
> + */
> +
> +#include "landlock_common.h"
> +
> +static struct landlock_ruleset_attr *ruleset_attr;
> +static struct landlock_ruleset_attr *null_attr;
> +static size_t rule_size;
> +static size_t rule_small_size;
> +static size_t rule_big_size;
> +
> +static struct tcase {
> + struct landlock_ruleset_attr **attr;
> + uint64_t access_fs;
> + size_t *size;
> + uint32_t flags;
> + int exp_errno;
> + char *msg;
> +} tcases[] = {
> + {&ruleset_attr, -1, &rule_size, 0, EINVAL, "Unknown access"},
> + {&ruleset_attr, 0, &rule_small_size, 0, EINVAL, "Size is
> too small"},
> + {&ruleset_attr, 0, &rule_size, -1, EINVAL, "Unknown flags"},
> + {&ruleset_attr, 0, &rule_big_size, 0, E2BIG, "Size is too
> big"},
> + {&null_attr, 0, &rule_size, 0, EFAULT, "Invalid attr
> address"},
> + {&ruleset_attr, 0, &rule_size, 0, ENOMSG, "Empty accesses"},
> +};
> +
> +static void run(unsigned int n)
> +{
> + struct tcase *tc = &tcases[n];
> +
> + if (*tc->attr)
> + (*tc->attr)->handled_access_fs = tc->access_fs;
> +
> + TST_EXP_FAIL(tst_syscall(__NR_landlock_create_ruleset,
> + *tc->attr, *tc->size, tc->flags),
> + tc->exp_errno,
> + "%s",
> + tc->msg);
> +
> + if (TST_RET >= 0)
> + SAFE_CLOSE(TST_RET);
> +}
> +
> +static void setup(void)
> +{
> + verify_landlock_is_enabled();
> +
> + rule_size = sizeof(struct landlock_ruleset_attr);
> +
> +#ifdef HAVE_STRUCT_LANDLOCK_RULESET_ATTR_HANDLED_ACCESS_NET
> + rule_small_size = rule_size - sizeof(uint64_t);
>
>
> This is incorrect, at least decrease 1 more number:
> rule_small_size = rule_size - sizeof(uint64_t) - 1;
>
> But, those are quite unnecessary to add the if macro conditions,
> as the kernel code explicitly compares the minimal struct with
> handled_access_fs via:
>
> offsetofend(typeof(ruleset_attr), handled_access_fs)
>
I usually don't look at the kernel source code to write tests, because
for us it should be a black box that could have wrong documentation.
That's also the way we find bugs.
I would go for still using the macros, but removing 1 more byte from the
size when handled_access_net is defined.
> (and Mickael said it should never change for backward compatibility
> reason)
>
> So it should be just simple like:
>
> --- a/testcases/kernel/syscalls/landlock/landlock01.c
> +++ b/testcases/kernel/syscalls/landlock/landlock01.c
> @@ -62,11 +62,15 @@ static void setup(void)
>
> rule_size = sizeof(struct landlock_ruleset_attr);
>
> -#ifdef HAVE_STRUCT_LANDLOCK_RULESET_ATTR_HANDLED_ACCESS_NET
> - rule_small_size = rule_size - sizeof(uint64_t);
> -#else
> - rule_small_size = rule_size - 1;
> -#endif
> + /*
> + * The new kernel introduces a new field 'handled_access_net'
> in the
> + * structure 'landlock_ruleset_attr'. However, in the function
> + * 'landlock_create_ruleset()', it still uses the first field
> + * 'handled_access_fs' to calculate the minimal size for backward
> + * compatibility reason. Therefore, here test 'sizeof(__u64) -
> 1' is
> + * sufficient to determine the minimum size for 'rule_small_size'.
> + */
> + rule_small_size = sizeof(__u64) - 1;
>
> rule_big_size = SAFE_SYSCONF(_SC_PAGESIZE) + 1;
> }
>
> +#else
> + rule_small_size = rule_size - 1;
> +#endif
> +
> + rule_big_size = SAFE_SYSCONF(_SC_PAGESIZE) + 1;
> +}
> +
> +static struct tst_test test = {
> + .test = run,
> + .tcnt = ARRAY_SIZE(tcases),
> + .setup = setup,
> + .min_kver = "5.13",
> + .needs_root = 1,
> + .needs_kconfigs = (const char *[]) {
> + "CONFIG_SECURITY_LANDLOCK=y",
> + NULL
> + },
> + .bufs = (struct tst_buffers []) {
> + {&ruleset_attr, .size = sizeof(struct
> landlock_ruleset_attr)},
> + {},
> + },
> + .caps = (struct tst_cap []) {
> + TST_CAP(TST_CAP_REQ, CAP_SYS_ADMIN),
> + {}
> + },
> +};
> diff --git a/testcases/kernel/syscalls/landlock/landlock_common.h
> b/testcases/kernel/syscalls/landlock/landlock_common.h
> new file mode 100644
> index 000000000..66f8fd19a
> --- /dev/null
> +++ b/testcases/kernel/syscalls/landlock/landlock_common.h
> @@ -0,0 +1,74 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (C) 2024 SUSE LLC Andrea Cervesato
> <andrea.cervesato@suse.com>
> + */
> +
> +#ifndef LANDLOCK_COMMON_H
> +
> +#include "tst_test.h"
> +#include "lapi/prctl.h"
> +#include "lapi/fcntl.h"
> +#include "lapi/landlock.h"
> +
> +static inline void verify_landlock_is_enabled(void)
> +{
> + int abi;
> +
> + abi = tst_syscall(__NR_landlock_create_ruleset,
> + NULL, 0, LANDLOCK_CREATE_RULESET_VERSION);
> +
> + if (abi < 0) {
> + if (errno == EOPNOTSUPP) {
> + tst_brk(TCONF, "Landlock is currently
> disabled. "
> + "Please enable it either via
> CONFIG_LSM or "
> + "'lsm' kernel parameter.");
> + }
> +
> + tst_brk(TBROK | TERRNO, "landlock_create_ruleset
> error");
> + }
> +
> + tst_res(TINFO, "Landlock ABI v%d", abi);
> +}
> +
> +static inline void apply_landlock_rule(
> + struct landlock_path_beneath_attr *path_beneath_attr,
> + const int ruleset_fd,
> + const int access,
> + const char *path)
> +{
> + path_beneath_attr->allowed_access = access;
> + path_beneath_attr->parent_fd = SAFE_OPEN(path, O_PATH |
> O_CLOEXEC);
> +
> + SAFE_LANDLOCK_ADD_RULE(
> + ruleset_fd,
> + LANDLOCK_RULE_PATH_BENEATH,
> + path_beneath_attr,
> + 0);
> +
> + SAFE_CLOSE(path_beneath_attr->parent_fd);
> +}
> +
> +static inline void enforce_ruleset(const int ruleset_fd)
> +{
> + SAFE_PRCTL(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
> + SAFE_LANDLOCK_RESTRICT_SELF(ruleset_fd, 0);
> +}
> +
> +static inline void apply_landlock_layer(
> + struct landlock_ruleset_attr *ruleset_attr,
> + struct landlock_path_beneath_attr *path_beneath_attr,
> + const char *path,
> + const int access)
> +{
> + int ruleset_fd;
> +
> + ruleset_fd = SAFE_LANDLOCK_CREATE_RULESET(
> + ruleset_attr, sizeof(struct
> landlock_ruleset_attr), 0);
> +
> + apply_landlock_rule(path_beneath_attr, ruleset_fd, access,
> path);
> + enforce_ruleset(ruleset_fd);
> +
> + SAFE_CLOSE(ruleset_fd);
> +}
> +
> +#endif
>
> --
> 2.43.0
>
>
>
> --
> Regards,
> Li Wang
Andrea
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