test_core_reloc_kernel.c

  1// SPDX-License-Identifier: GPL-2.0
  2// Copyright (c) 2019 Facebook
  3
  4#include <linux/bpf.h>
  5#include <stdint.h>
  6#include <stdbool.h>
  7#include <bpf/bpf_helpers.h>
  8#include <bpf/bpf_core_read.h>
  9
 10char _license[] SEC("license") = "GPL";
 11
 12struct {
 13	char in[256];
 14	char out[256];
 15	bool skip;
 16	uint64_t my_pid_tgid;
 17} data = {};
 18
 19struct core_reloc_kernel_output {
 20	int valid[10];
 21	/* we have test_progs[-flavor], so cut flavor part */
 22	char comm[sizeof("test_progs")];
 23	int comm_len;
 24	bool local_task_struct_matches;
 25};
 26
 27struct task_struct {
 28	int pid;
 29	int tgid;
 30	char comm[16];
 31	struct task_struct *group_leader;
 32};
 33
 34struct mm_struct___wrong {
 35    int abc_whatever_should_not_exist;
 36};
 37
 38struct task_struct___local {
 39    int pid;
 40    struct mm_struct___wrong *mm;
 41};
 42
 43#define CORE_READ(dst, src) bpf_core_read(dst, sizeof(*(dst)), src)
 44
 45SEC("raw_tracepoint/sys_enter")
 46int test_core_kernel(void *ctx)
 47{
 48	/* Support for the BPF_TYPE_MATCHES argument to the
 49	 * __builtin_preserve_type_info builtin was added at some point during
 50	 * development of clang 15 and it's what we require for this test.
 51	 */
 52#if __has_builtin(__builtin_preserve_type_info) && __clang_major__ >= 15
 53	struct task_struct *task = (void *)bpf_get_current_task();
 54	struct core_reloc_kernel_output *out = (void *)&data.out;
 55	uint64_t pid_tgid = bpf_get_current_pid_tgid();
 56	int32_t real_tgid = (int32_t)pid_tgid;
 57	int pid, tgid;
 58
 59	if (data.my_pid_tgid != pid_tgid)
 60		return 0;
 61
 62	if (CORE_READ(&pid, &task->pid) ||
 63	    CORE_READ(&tgid, &task->tgid))
 64		return 1;
 65
 66	/* validate pid + tgid matches */
 67	out->valid[0] = (((uint64_t)pid << 32) | tgid) == pid_tgid;
 68
 69	/* test variadic BPF_CORE_READ macros */
 70	out->valid[1] = BPF_CORE_READ(task,
 71				      tgid) == real_tgid;
 72	out->valid[2] = BPF_CORE_READ(task,
 73				      group_leader,
 74				      tgid) == real_tgid;
 75	out->valid[3] = BPF_CORE_READ(task,
 76				      group_leader, group_leader,
 77				      tgid) == real_tgid;
 78	out->valid[4] = BPF_CORE_READ(task,
 79				      group_leader, group_leader, group_leader,
 80				      tgid) == real_tgid;
 81	out->valid[5] = BPF_CORE_READ(task,
 82				      group_leader, group_leader, group_leader,
 83				      group_leader,
 84				      tgid) == real_tgid;
 85	out->valid[6] = BPF_CORE_READ(task,
 86				      group_leader, group_leader, group_leader,
 87				      group_leader, group_leader,
 88				      tgid) == real_tgid;
 89	out->valid[7] = BPF_CORE_READ(task,
 90				      group_leader, group_leader, group_leader,
 91				      group_leader, group_leader, group_leader,
 92				      tgid) == real_tgid;
 93	out->valid[8] = BPF_CORE_READ(task,
 94				      group_leader, group_leader, group_leader,
 95				      group_leader, group_leader, group_leader,
 96				      group_leader,
 97				      tgid) == real_tgid;
 98	out->valid[9] = BPF_CORE_READ(task,
 99				      group_leader, group_leader, group_leader,
100				      group_leader, group_leader, group_leader,
101				      group_leader, group_leader,
102				      tgid) == real_tgid;
103
104	/* test BPF_CORE_READ_STR_INTO() returns correct code and contents */
105	out->comm_len = BPF_CORE_READ_STR_INTO(
106		&out->comm, task,
107		group_leader, group_leader, group_leader, group_leader,
108		group_leader, group_leader, group_leader, group_leader,
109		comm);
110
111	out->local_task_struct_matches = bpf_core_type_matches(struct task_struct___local);
112#else
113	data.skip = true;
114#endif
115	return 0;
116}
117