Commit 18678cf0 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

selftests/bpf: add tests for BPF object load with implicit token 



Add a test to validate libbpf's implicit BPF token creation from default
BPF FS location (/sys/fs/bpf). Also validate that disabling this
implicit BPF token creation works.

Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231213190842.3844987-9-andrii@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 98e0eaa3

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

+76 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/unistd.h>

#include <linux/mount.h>

#include <sys/socket.h>

#include <sys/stat.h>

#include <sys/syscall.h>

#include <sys/un.h>

#include "priv_map.skel.h"
@@ -45,6 +46,13 @@ static inline int sys_fsmount(int fs_fd, unsigned flags, unsigned ms_flags) 
	return syscall(__NR_fsmount, fs_fd, flags, ms_flags);

}



static inline int sys_move_mount(int from_dfd, const char *from_path,

				 int to_dfd, const char *to_path,

				 unsigned flags)

{

	return syscall(__NR_move_mount, from_dfd, from_path, to_dfd, to_path, flags);

}



static int drop_priv_caps(__u64 *old_caps)

{

	return cap_disable_effective((1ULL << CAP_BPF) |
@@ -761,6 +769,63 @@ static int userns_obj_priv_btf_success(int mnt_fd) 
	return validate_struct_ops_load(mnt_fd, true /* should succeed */);

}



static int userns_obj_priv_implicit_token(int mnt_fd)

{

	LIBBPF_OPTS(bpf_object_open_opts, opts);

	struct dummy_st_ops_success *skel;

	int err;



	/* before we mount BPF FS with token delegation, struct_ops skeleton

	 * should fail to load

	 */

	skel = dummy_st_ops_success__open_and_load();

	if (!ASSERT_ERR_PTR(skel, "obj_tokenless_load")) {

		dummy_st_ops_success__destroy(skel);

		return -EINVAL;

	}



	/* mount custom BPF FS over /sys/fs/bpf so that libbpf can create BPF

	 * token automatically and implicitly

	 */

	err = sys_move_mount(mnt_fd, "", AT_FDCWD, "/sys/fs/bpf", MOVE_MOUNT_F_EMPTY_PATH);

	if (!ASSERT_OK(err, "move_mount_bpffs"))

		return -EINVAL;



	/* now the same struct_ops skeleton should succeed thanks to libppf

	 * creating BPF token from /sys/fs/bpf mount point

	 */

	skel = dummy_st_ops_success__open_and_load();

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

		return -EINVAL;



	dummy_st_ops_success__destroy(skel);



	/* now disable implicit token through empty bpf_token_path, should fail */

	opts.bpf_token_path = "";

	skel = dummy_st_ops_success__open_opts(&opts);

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

		return -EINVAL;



	err = dummy_st_ops_success__load(skel);

	dummy_st_ops_success__destroy(skel);

	if (!ASSERT_ERR(err, "obj_empty_token_path_load"))

		return -EINVAL;



	/* now disable implicit token through negative bpf_token_fd, should fail */

	opts.bpf_token_path = NULL;

	opts.bpf_token_fd = -1;

	skel = dummy_st_ops_success__open_opts(&opts);

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

		return -EINVAL;



	err = dummy_st_ops_success__load(skel);

	dummy_st_ops_success__destroy(skel);

	if (!ASSERT_ERR(err, "obj_neg_token_fd_load"))

		return -EINVAL;



	return 0;

}



#define bit(n) (1ULL << (n))



void test_token(void)
@@ -828,4 +893,15 @@ void test_token(void) 


		subtest_userns(&opts, userns_obj_priv_btf_success);

	}

	if (test__start_subtest("obj_priv_implicit_token")) {

		struct bpffs_opts opts = {

			/* allow BTF loading */

			.cmds = bit(BPF_BTF_LOAD) | bit(BPF_MAP_CREATE) | bit(BPF_PROG_LOAD),

			.maps = bit(BPF_MAP_TYPE_STRUCT_OPS),

			.progs = bit(BPF_PROG_TYPE_STRUCT_OPS),

			.attachs = ~0ULL,

		};



		subtest_userns(&opts, userns_obj_priv_implicit_token);

	}

}