[LTP] [PATCH 05/10] Add landlock01 test
Li Wang
liwang@redhat.com
Tue Jul 2 11:09:05 CEST 2024
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
>> +
>> +LDLIBS += -lc
>> +
>> +include $(top_srcdir)/include/mk/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
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