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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
#include <test_progs.h>
#include <bpf/btf.h>
#include "test_log_buf.skel.h"
static bool check_prog_load(int prog_fd, bool expect_err, const char *tag)
{
if (expect_err) {
if (!ASSERT_LT(prog_fd, 0, tag)) {
close(prog_fd);
return false;
}
} else /* !expect_err */ {
if (!ASSERT_GT(prog_fd, 0, tag))
return false;
}
if (prog_fd >= 0)
close(prog_fd);
return true;
}
static struct {
/* strategically placed before others to avoid accidental modification by kernel */
char filler[1024];
char buf[1024];
/* strategically placed after buf[] to catch more accidental corruptions */
char reference[1024];
} logs;
static const struct bpf_insn *insns;
static size_t insn_cnt;
static int load_prog(struct bpf_prog_load_opts *opts, bool expect_load_error)
{
int prog_fd;
prog_fd = bpf_prog_load(BPF_PROG_TYPE_RAW_TRACEPOINT, "log_prog",
"GPL", insns, insn_cnt, opts);
check_prog_load(prog_fd, expect_load_error, "prog_load");
return prog_fd;
}
static void verif_log_subtest(const char *name, bool expect_load_error, int log_level)
{
LIBBPF_OPTS(bpf_prog_load_opts, opts);
char *exp_log, prog_name[16], op_name[32];
struct test_log_buf *skel;
struct bpf_program *prog;
size_t fixed_log_sz;
__u32 log_true_sz_fixed, log_true_sz_rolling;
int i, mode, err, prog_fd, res;
skel = test_log_buf__open();
if (!ASSERT_OK_PTR(skel, "skel_open"))
return;
bpf_object__for_each_program(prog, skel->obj) {
if (strcmp(bpf_program__name(prog), name) == 0)
bpf_program__set_autoload(prog, true);
else
bpf_program__set_autoload(prog, false);
}
err = test_log_buf__load(skel);
if (!expect_load_error && !ASSERT_OK(err, "unexpected_load_failure"))
goto cleanup;
if (expect_load_error && !ASSERT_ERR(err, "unexpected_load_success"))
goto cleanup;
insns = bpf_program__insns(skel->progs.good_prog);
insn_cnt = bpf_program__insn_cnt(skel->progs.good_prog);
opts.log_buf = logs.reference;
opts.log_size = sizeof(logs.reference);
opts.log_level = log_level | 8 /* BPF_LOG_FIXED */;
load_prog(&opts, expect_load_error);
fixed_log_sz = strlen(logs.reference) + 1;
if (!ASSERT_GT(fixed_log_sz, 50, "fixed_log_sz"))
goto cleanup;
memset(logs.reference + fixed_log_sz, 0, sizeof(logs.reference) - fixed_log_sz);
/* validate BPF_LOG_FIXED works as verifier log used to work, that is:
* we get -ENOSPC and beginning of the full verifier log. This only
* works for log_level 2 and log_level 1 + failed program. For log
* level 2 we don't reset log at all. For log_level 1 + failed program
* we don't get to verification stats output. With log level 1
* for successful program final result will be just verifier stats.
* But if provided too short log buf, kernel will NULL-out log->ubuf
* and will stop emitting further log. This means we'll never see
* predictable verifier stats.
* Long story short, we do the following -ENOSPC test only for
* predictable combinations.
*/
if (log_level >= 2 || expect_load_error) {
opts.log_buf = logs.buf;
opts.log_level = log_level | 8; /* fixed-length log */
opts.log_size = 25;
prog_fd = bpf_prog_load(BPF_PROG_TYPE_RAW_TRACEPOINT, "log_fixed25",
"GPL", insns, insn_cnt, &opts);
if (!ASSERT_EQ(prog_fd, -ENOSPC, "unexpected_log_fixed_prog_load_result")) {
if (prog_fd >= 0)
close(prog_fd);
goto cleanup;
}
if (!ASSERT_EQ(strlen(logs.buf), 24, "log_fixed_25"))
goto cleanup;
if (!ASSERT_STRNEQ(logs.buf, logs.reference, 24, op_name))
goto cleanup;
}
/* validate rolling verifier log logic: try all variations of log buf
* length to force various truncation scenarios
*/
opts.log_buf = logs.buf;
/* rotating mode, then fixed mode */
for (mode = 1; mode >= 0; mode--) {
/* prefill logs.buf with 'A's to detect any write beyond allowed length */
memset(logs.filler, 'A', sizeof(logs.filler));
logs.filler[sizeof(logs.filler) - 1] = '\0';
memset(logs.buf, 'A', sizeof(logs.buf));
logs.buf[sizeof(logs.buf) - 1] = '\0';
for (i = 1; i < fixed_log_sz; i++) {
opts.log_size = i;
opts.log_level = log_level | (mode ? 0 : 8 /* BPF_LOG_FIXED */);
snprintf(prog_name, sizeof(prog_name),
"log_%s_%d", mode ? "roll" : "fixed", i);
prog_fd = bpf_prog_load(BPF_PROG_TYPE_RAW_TRACEPOINT, prog_name,
"GPL", insns, insn_cnt, &opts);
snprintf(op_name, sizeof(op_name),
"log_%s_prog_load_%d", mode ? "roll" : "fixed", i);
if (!ASSERT_EQ(prog_fd, -ENOSPC, op_name)) {
if (prog_fd >= 0)
close(prog_fd);
goto cleanup;
}
snprintf(op_name, sizeof(op_name),
"log_%s_strlen_%d", mode ? "roll" : "fixed", i);
ASSERT_EQ(strlen(logs.buf), i - 1, op_name);
if (mode)
exp_log = logs.reference + fixed_log_sz - i;
else
exp_log = logs.reference;
snprintf(op_name, sizeof(op_name),
"log_%s_contents_%d", mode ? "roll" : "fixed", i);
if (!ASSERT_STRNEQ(logs.buf, exp_log, i - 1, op_name)) {
printf("CMP:%d\nS1:'%s'\nS2:'%s'\n",
strncmp(logs.buf, exp_log, i - 1),
logs.buf, exp_log);
goto cleanup;
}
/* check that unused portions of logs.buf is not overwritten */
snprintf(op_name, sizeof(op_name),
"log_%s_unused_%d", mode ? "roll" : "fixed", i);
if (!ASSERT_STREQ(logs.buf + i, logs.filler + i, op_name)) {
printf("CMP:%d\nS1:'%s'\nS2:'%s'\n",
strcmp(logs.buf + i, logs.filler + i),
logs.buf + i, logs.filler + i);
goto cleanup;
}
}
}
/* (FIXED) get actual log size */
opts.log_buf = logs.buf;
opts.log_level = log_level | 8; /* BPF_LOG_FIXED */
opts.log_size = sizeof(logs.buf);
res = load_prog(&opts, expect_load_error);
ASSERT_NEQ(res, -ENOSPC, "prog_load_res_fixed");
log_true_sz_fixed = opts.log_true_size;
ASSERT_GT(log_true_sz_fixed, 0, "log_true_sz_fixed");
/* (ROLLING) get actual log size */
opts.log_buf = logs.buf;
opts.log_level = log_level;
opts.log_size = sizeof(logs.buf);
res = load_prog(&opts, expect_load_error);
ASSERT_NEQ(res, -ENOSPC, "prog_load_res_rolling");
log_true_sz_rolling = opts.log_true_size;
ASSERT_EQ(log_true_sz_rolling, log_true_sz_fixed, "log_true_sz_eq");
/* (FIXED) expect -ENOSPC for one byte short log */
opts.log_buf = logs.buf;
opts.log_level = log_level | 8; /* BPF_LOG_FIXED */
opts.log_size = log_true_sz_fixed - 1;
res = load_prog(&opts, true /* should fail */);
ASSERT_EQ(res, -ENOSPC, "prog_load_res_too_short_fixed");
/* (FIXED) expect *not* -ENOSPC with exact log_true_size buffer */
opts.log_buf = logs.buf;
opts.log_level = log_level | 8; /* BPF_LOG_FIXED */
opts.log_size = log_true_sz_fixed;
res = load_prog(&opts, expect_load_error);
ASSERT_NEQ(res, -ENOSPC, "prog_load_res_just_right_fixed");
/* (ROLLING) expect -ENOSPC for one byte short log */
opts.log_buf = logs.buf;
opts.log_level = log_level;
opts.log_size = log_true_sz_rolling - 1;
res = load_prog(&opts, true /* should fail */);
ASSERT_EQ(res, -ENOSPC, "prog_load_res_too_short_rolling");
/* (ROLLING) expect *not* -ENOSPC with exact log_true_size buffer */
opts.log_buf = logs.buf;
opts.log_level = log_level;
opts.log_size = log_true_sz_rolling;
res = load_prog(&opts, expect_load_error);
ASSERT_NEQ(res, -ENOSPC, "prog_load_res_just_right_rolling");
cleanup:
test_log_buf__destroy(skel);
}
void test_verifier_log(void)
{
if (test__start_subtest("good_prog-level1"))
verif_log_subtest("good_prog", false, 1);
if (test__start_subtest("good_prog-level2"))
verif_log_subtest("good_prog", false, 2);
if (test__start_subtest("bad_prog-level1"))
verif_log_subtest("bad_prog", true, 1);
if (test__start_subtest("bad_prog-level2"))
verif_log_subtest("bad_prog", true, 2);
}
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