Commit ecce368d authored by Roberto Sassu's avatar Roberto Sassu Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add additional tests for bpf_lookup_*_key() 



Add a test to ensure that bpf_lookup_user_key() creates a referenced
special keyring when the KEY_LOOKUP_CREATE flag is passed to this function.

Ensure that the kfunc rejects invalid flags.

Ensure that a keyring can be obtained from bpf_lookup_system_key() when one
of the pre-determined keyring IDs is provided.

The test is currently blacklisted for s390x (JIT does not support calling
kernel function).

Signed-off-by: default avatarRoberto Sassu <roberto.sassu@huawei.com>
Link: https://lore.kernel.org/r/20220920075951.929132-12-roberto.sassu@huaweicloud.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 7c036ed9

tools/testing/selftests/bpf/DENYLIST.s390x

+1 −0
Original line number Diff line number Diff line
@@ -72,3 +72,4 @@ cgroup_hierarchical_stats # JIT does not support calling kernel f 
htab_update                              # failed to attach: ERROR: strerror_r(-524)=22                                (trampoline)

tracing_struct                           # failed to auto-attach: -524                                                 (trampoline)

user_ringbuf                             # failed to find kernel BTF type ID of '__s390x_sys_prctl': -3                (?)

lookup_key                               # JIT does not support calling kernel function                                (kfunc)

tools/testing/selftests/bpf/prog_tests/lookup_key.c

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+112 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



/*

 * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH

 *

 * Author: Roberto Sassu <roberto.sassu@huawei.com>

 */



#include <linux/keyctl.h>

#include <test_progs.h>



#include "test_lookup_key.skel.h"



#define KEY_LOOKUP_CREATE	0x01

#define KEY_LOOKUP_PARTIAL	0x02



static bool kfunc_not_supported;



static int libbpf_print_cb(enum libbpf_print_level level, const char *fmt,

			   va_list args)

{

	char *func;



	if (strcmp(fmt, "libbpf: extern (func ksym) '%s': not found in kernel or module BTFs\n"))

		return 0;



	func = va_arg(args, char *);



	if (strcmp(func, "bpf_lookup_user_key") && strcmp(func, "bpf_key_put") &&

	    strcmp(func, "bpf_lookup_system_key"))

		return 0;



	kfunc_not_supported = true;

	return 0;

}



void test_lookup_key(void)

{

	libbpf_print_fn_t old_print_cb;

	struct test_lookup_key *skel;

	__u32 next_id;

	int ret;



	skel = test_lookup_key__open();

	if (!ASSERT_OK_PTR(skel, "test_lookup_key__open"))

		return;



	old_print_cb = libbpf_set_print(libbpf_print_cb);

	ret = test_lookup_key__load(skel);

	libbpf_set_print(old_print_cb);



	if (ret < 0 && kfunc_not_supported) {

		printf("%s:SKIP:bpf_lookup_*_key(), bpf_key_put() kfuncs not supported\n",

		       __func__);

		test__skip();

		goto close_prog;

	}



	if (!ASSERT_OK(ret, "test_lookup_key__load"))

		goto close_prog;



	ret = test_lookup_key__attach(skel);

	if (!ASSERT_OK(ret, "test_lookup_key__attach"))

		goto close_prog;



	skel->bss->monitored_pid = getpid();

	skel->bss->key_serial = KEY_SPEC_THREAD_KEYRING;



	/* The thread-specific keyring does not exist, this test fails. */

	skel->bss->flags = 0;



	ret = bpf_prog_get_next_id(0, &next_id);

	if (!ASSERT_LT(ret, 0, "bpf_prog_get_next_id"))

		goto close_prog;



	/* Force creation of the thread-specific keyring, this test succeeds. */

	skel->bss->flags = KEY_LOOKUP_CREATE;



	ret = bpf_prog_get_next_id(0, &next_id);

	if (!ASSERT_OK(ret, "bpf_prog_get_next_id"))

		goto close_prog;



	/* Pass both lookup flags for parameter validation. */

	skel->bss->flags = KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL;



	ret = bpf_prog_get_next_id(0, &next_id);

	if (!ASSERT_OK(ret, "bpf_prog_get_next_id"))

		goto close_prog;



	/* Pass invalid flags. */

	skel->bss->flags = UINT64_MAX;



	ret = bpf_prog_get_next_id(0, &next_id);

	if (!ASSERT_LT(ret, 0, "bpf_prog_get_next_id"))

		goto close_prog;



	skel->bss->key_serial = 0;

	skel->bss->key_id = 1;



	ret = bpf_prog_get_next_id(0, &next_id);

	if (!ASSERT_OK(ret, "bpf_prog_get_next_id"))

		goto close_prog;



	skel->bss->key_id = UINT32_MAX;



	ret = bpf_prog_get_next_id(0, &next_id);

	ASSERT_LT(ret, 0, "bpf_prog_get_next_id");



close_prog:

	skel->bss->monitored_pid = 0;

	test_lookup_key__destroy(skel);

}

tools/testing/selftests/bpf/progs/test_lookup_key.c

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// SPDX-License-Identifier: GPL-2.0



/*

 * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH

 *

 * Author: Roberto Sassu <roberto.sassu@huawei.com>

 */



#include "vmlinux.h"

#include <errno.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>



char _license[] SEC("license") = "GPL";



__u32 monitored_pid;

__u32 key_serial;

__u32 key_id;

__u64 flags;



extern struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym;

extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;

extern void bpf_key_put(struct bpf_key *key) __ksym;



SEC("lsm.s/bpf")

int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size)

{

	struct bpf_key *bkey;

	__u32 pid;



	pid = bpf_get_current_pid_tgid() >> 32;

	if (pid != monitored_pid)

		return 0;



	if (key_serial)

		bkey = bpf_lookup_user_key(key_serial, flags);

	else

		bkey = bpf_lookup_system_key(key_id);



	if (!bkey)

		return -ENOENT;



	bpf_key_put(bkey);



	return 0;

}