[LTP] [PATCH 05/10] Add landlock01 test
Andrea Cervesato
andrea.cervesato@suse.com
Tue Jul 2 11:20:43 CEST 2024
Hi!
On 7/2/24 11:09, Li Wang wrote:
>
>
> On Tue, Jul 2, 2024 at 4:34 PM Li Wang <liwang@redhat.com> wrote:
>
>
>
> On Mon, Jul 1, 2024 at 11:43 PM Andrea Cervesato
> <andrea.cervesato@suse.de> wrote:
>
> From: Andrea Cervesato <andrea.cervesato@suse.com>
>
>
> Reviewed-by: Li Wang <liwang@redhat.com>
>
> Mostly code is pretty good, but just a tiny issue comment inline
> below.
>
>
> 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)
>
> Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
> ---
> runtest/syscalls | 2 +
> testcases/kernel/syscalls/landlock/.gitignore | 1 +
> testcases/kernel/syscalls/landlock/Makefile | 10 +++
> testcases/kernel/syscalls/landlock/landlock01.c | 87
> ++++++++++++++++++++++
> .../kernel/syscalls/landlock/landlock_common.h | 74
> ++++++++++++++++++
> 5 files changed, 174 insertions(+)
>
> diff --git a/runtest/syscalls b/runtest/syscalls
> index 44a577db3..4c566d95f 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..4b3e3fd8f
> --- /dev/null
> +++ b/testcases/kernel/syscalls/landlock/Makefile
> @@ -0,0 +1,10 @@
> +# 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>
> +
> +LDLIBS += -lc
> +
> +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..9f8c6489c
> --- /dev/null
> +++ b/testcases/kernel/syscalls/landlock/landlock01.c
> @@ -0,0 +1,87 @@
> +// 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);
> +
> + rule_small_size = rule_size - 1;
>
>
> Here minus 1 is not enough, we have to decrease more than 8
> otherwise it just returns ENOMSG.
>
> landlock01.c:49: TFAIL: Size is too small expected EINVAL:
> ENOMSG (42)
>
> rule_small_size = rule_size - 9;
>
> or, we use a small enough type:
>
> rule_small_size = sizeof(int);
>
> my test kernel is 6.9.6-200.fc40.x86_64.
>
> I haven't figured out that's why, but maybe inside the
> landlock_create_ruleset()
> syscall compare the size unprecisely. Something like invoke the
> copy_min_struct_from_user.
>
> 199 err = copy_min_struct_from_user(&ruleset_attr,
> sizeof(ruleset_attr),
> 200 offsetofend(typeof(ruleset_attr),
> 201 handled_access_fs),
> 202 attr, size);
>
> ...
>
> 32 #define offsetofend(TYPE, MEMBER) \
> 33 (offsetof(TYPE, MEMBER) + sizeof_field(TYPE, MEMBER))
>
> This needs more investigation...
>
>
> I guess I found the reason, kernel commit fff69fb03dde1df introducing
> a new
> field 'handled_access_net' in the structure, but in the
> landlock_create_ruleset(),
> it still uses the first field 'handled_access_fs' to count min size,
> so that why
> decrease 1 is useless in your test.
>
> I will send out a RFC patch to LKML for that. Thanks!
>
> --- a/security/landlock/syscalls.c
> +++ b/security/landlock/syscalls.c
> @@ -198,7 +198,7 @@ SYSCALL_DEFINE3(landlock_create_ruleset,
> /* Copies raw user space buffer. */
> err = copy_min_struct_from_user(&ruleset_attr,
> sizeof(ruleset_attr),
> offsetofend(typeof(ruleset_attr),
> - handled_access_fs),
> + handled_access_net),
> attr, size);
> if (err)
> return err;
>
>
>
> --
> Regards,
> Li Wang
First of all, thanks for the review. Super for the bug in the landlock code.
Regards,
Andrea Cervesato
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