From 9fc4476a08b6dc61e406c2c0c4e0690512f60e82 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Sat, 19 Mar 2022 13:38:27 +0530 Subject: [PATCH] selftests/bpf: Test for writes to map key from BPF helpers When invoking bpf_for_each_map_elem callback, we are passed a PTR_TO_MAP_KEY, previously writes to this through helper may be allowed, but the fix in previous patches is meant to prevent that case. The test case tries to pass it as writable memory to helper, and fails test if it succeeds to pass the verifier. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20220319080827.73251-6-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/prog_tests/for_each.c | 12 ++++++++++ .../bpf/progs/for_each_map_elem_write_key.c | 27 ++++++++++++++++++++++ 2 files changed, 39 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/for_each_map_elem_write_key.c diff --git a/tools/testing/selftests/bpf/prog_tests/for_each.c b/tools/testing/selftests/bpf/prog_tests/for_each.c index 044df13..754e809 100644 --- a/tools/testing/selftests/bpf/prog_tests/for_each.c +++ b/tools/testing/selftests/bpf/prog_tests/for_each.c @@ -4,6 +4,7 @@ #include #include "for_each_hash_map_elem.skel.h" #include "for_each_array_map_elem.skel.h" +#include "for_each_map_elem_write_key.skel.h" static unsigned int duration; @@ -129,10 +130,21 @@ out: for_each_array_map_elem__destroy(skel); } +static void test_write_map_key(void) +{ + struct for_each_map_elem_write_key *skel; + + skel = for_each_map_elem_write_key__open_and_load(); + if (!ASSERT_ERR_PTR(skel, "for_each_map_elem_write_key__open_and_load")) + for_each_map_elem_write_key__destroy(skel); +} + void test_for_each(void) { if (test__start_subtest("hash_map")) test_hash_map(); if (test__start_subtest("array_map")) test_array_map(); + if (test__start_subtest("write_map_key")) + test_write_map_key(); } diff --git a/tools/testing/selftests/bpf/progs/for_each_map_elem_write_key.c b/tools/testing/selftests/bpf/progs/for_each_map_elem_write_key.c new file mode 100644 index 0000000..8e54586 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/for_each_map_elem_write_key.c @@ -0,0 +1,27 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, 1); + __type(key, __u32); + __type(value, __u64); +} array_map SEC(".maps"); + +static __u64 +check_array_elem(struct bpf_map *map, __u32 *key, __u64 *val, + void *data) +{ + bpf_get_current_comm(key, sizeof(*key)); + return 0; +} + +SEC("raw_tp/sys_enter") +int test_map_key_write(const void *ctx) +{ + bpf_for_each_map_elem(&array_map, check_array_elem, NULL, 0); + return 0; +} + +char _license[] SEC("license") = "GPL"; -- 2.7.4