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selftests/bpf: allow checking xlated programs in verifier_* tests
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Add a macro __xlated("...") for use with test_loader tests.

When such annotations are present for the test case:
- bpf_prog_get_info_by_fd() is used to get BPF program after all
  rewrites are applied by verifier.
- the program is disassembled and patterns specified in __xlated are
  searched for in the disassembly text.

__xlated matching follows the same mechanics as __msg:
each subsequent pattern is matched from the point where
previous pattern ended.

This allows to write tests like below, where the goal is to verify the
behavior of one of the of the transformations applied by verifier:

    SEC("raw_tp")
    __xlated("1: w0 = ")
    __xlated("2: r0 = &(void __percpu *)(r0)")
    __xlated("3: r0 = *(u32 *)(r0 +0)")
    __xlated("4: exit")
    __success __naked void simple(void)
    {
            asm volatile (
            "call %[bpf_get_smp_processor_id];"
            "exit;"
            :
            : __imm(bpf_get_smp_processor_id)
            : __clobber_all);
    }

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240722233844.1406874-9-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
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@eddyz87 @anakryiko
eddyz87 authored and anakryiko committed Jul 29, 2024
1 parent 64f01e9 commit 9c9f733
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Showing 2 changed files with 84 additions and 3 deletions.
5 changes: 5 additions & 0 deletions tools/testing/selftests/bpf/progs/bpf_misc.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,9 @@
*
* __regex Same as __msg, but using a regular expression.
* __regex_unpriv Same as __msg_unpriv but using a regular expression.
* __xlated Expect a line in a disassembly log after verifier applies rewrites.
* Multiple __xlated attributes could be specified.
* __xlated_unpriv Same as __xlated but for unprivileged mode.
*
* __success Expect program load success in privileged mode.
* __success_unpriv Expect program load success in unprivileged mode.
Expand Down Expand Up @@ -63,11 +66,13 @@
*/
#define __msg(msg) __attribute__((btf_decl_tag("comment:test_expect_msg=" msg)))
#define __regex(regex) __attribute__((btf_decl_tag("comment:test_expect_regex=" regex)))
#define __xlated(msg) __attribute__((btf_decl_tag("comment:test_expect_xlated=" msg)))
#define __failure __attribute__((btf_decl_tag("comment:test_expect_failure")))
#define __success __attribute__((btf_decl_tag("comment:test_expect_success")))
#define __description(desc) __attribute__((btf_decl_tag("comment:test_description=" desc)))
#define __msg_unpriv(msg) __attribute__((btf_decl_tag("comment:test_expect_msg_unpriv=" msg)))
#define __regex_unpriv(regex) __attribute__((btf_decl_tag("comment:test_expect_regex_unpriv=" regex)))
#define __xlated_unpriv(msg) __attribute__((btf_decl_tag("comment:test_expect_xlated_unpriv=" msg)))
#define __failure_unpriv __attribute__((btf_decl_tag("comment:test_expect_failure_unpriv")))
#define __success_unpriv __attribute__((btf_decl_tag("comment:test_expect_success_unpriv")))
#define __log_level(lvl) __attribute__((btf_decl_tag("comment:test_log_level="#lvl)))
Expand Down
82 changes: 79 additions & 3 deletions tools/testing/selftests/bpf/test_loader.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
#include <bpf/btf.h>

#include "autoconf_helper.h"
#include "disasm_helpers.h"
#include "unpriv_helpers.h"
#include "cap_helpers.h"

Expand All @@ -19,10 +20,12 @@
#define TEST_TAG_EXPECT_SUCCESS "comment:test_expect_success"
#define TEST_TAG_EXPECT_MSG_PFX "comment:test_expect_msg="
#define TEST_TAG_EXPECT_REGEX_PFX "comment:test_expect_regex="
#define TEST_TAG_EXPECT_XLATED_PFX "comment:test_expect_xlated="
#define TEST_TAG_EXPECT_FAILURE_UNPRIV "comment:test_expect_failure_unpriv"
#define TEST_TAG_EXPECT_SUCCESS_UNPRIV "comment:test_expect_success_unpriv"
#define TEST_TAG_EXPECT_MSG_PFX_UNPRIV "comment:test_expect_msg_unpriv="
#define TEST_TAG_EXPECT_REGEX_PFX_UNPRIV "comment:test_expect_regex_unpriv="
#define TEST_TAG_EXPECT_XLATED_PFX_UNPRIV "comment:test_expect_xlated_unpriv="
#define TEST_TAG_LOG_LEVEL_PFX "comment:test_log_level="
#define TEST_TAG_PROG_FLAGS_PFX "comment:test_prog_flags="
#define TEST_TAG_DESCRIPTION_PFX "comment:test_description="
Expand Down Expand Up @@ -64,6 +67,7 @@ struct test_subspec {
char *name;
bool expect_failure;
struct expected_msgs expect_msgs;
struct expected_msgs expect_xlated;
int retval;
bool execute;
};
Expand Down Expand Up @@ -117,6 +121,8 @@ static void free_test_spec(struct test_spec *spec)
/* Deallocate expect_msgs arrays. */
free_msgs(&spec->priv.expect_msgs);
free_msgs(&spec->unpriv.expect_msgs);
free_msgs(&spec->priv.expect_xlated);
free_msgs(&spec->unpriv.expect_xlated);

free(spec->priv.name);
free(spec->unpriv.name);
Expand Down Expand Up @@ -299,6 +305,18 @@ static int parse_test_spec(struct test_loader *tester,
if (err)
goto cleanup;
spec->mode_mask |= UNPRIV;
} else if (str_has_pfx(s, TEST_TAG_EXPECT_XLATED_PFX)) {
msg = s + sizeof(TEST_TAG_EXPECT_XLATED_PFX) - 1;
err = push_msg(msg, NULL, &spec->priv.expect_xlated);
if (err)
goto cleanup;
spec->mode_mask |= PRIV;
} else if (str_has_pfx(s, TEST_TAG_EXPECT_XLATED_PFX_UNPRIV)) {
msg = s + sizeof(TEST_TAG_EXPECT_XLATED_PFX_UNPRIV) - 1;
err = push_msg(msg, NULL, &spec->unpriv.expect_xlated);
if (err)
goto cleanup;
spec->mode_mask |= UNPRIV;
} else if (str_has_pfx(s, TEST_TAG_RETVAL_PFX)) {
val = s + sizeof(TEST_TAG_RETVAL_PFX) - 1;
err = parse_retval(val, &spec->priv.retval, "__retval");
Expand Down Expand Up @@ -402,6 +420,16 @@ static int parse_test_spec(struct test_loader *tester,
goto cleanup;
}
}
if (spec->unpriv.expect_xlated.cnt == 0) {
for (i = 0; i < spec->priv.expect_xlated.cnt; i++) {
struct expect_msg *msg = &spec->priv.expect_xlated.patterns[i];

err = push_msg(msg->substr, msg->regex_str,
&spec->unpriv.expect_xlated);
if (err)
goto cleanup;
}
}
}

spec->valid = true;
Expand Down Expand Up @@ -449,7 +477,15 @@ static void emit_verifier_log(const char *log_buf, bool force)
fprintf(stdout, "VERIFIER LOG:\n=============\n%s=============\n", log_buf);
}

static void validate_msgs(char *log_buf, struct expected_msgs *msgs)
static void emit_xlated(const char *xlated, bool force)
{
if (!force && env.verbosity == VERBOSE_NONE)
return;
fprintf(stdout, "XLATED:\n=============\n%s=============\n", xlated);
}

static void validate_msgs(char *log_buf, struct expected_msgs *msgs,
void (*emit_fn)(const char *buf, bool force))
{
regmatch_t reg_match[1];
const char *log = log_buf;
Expand All @@ -473,7 +509,7 @@ static void validate_msgs(char *log_buf, struct expected_msgs *msgs)

if (!ASSERT_OK_PTR(match, "expect_msg")) {
if (env.verbosity == VERBOSE_NONE)
emit_verifier_log(log_buf, true /*force*/);
emit_fn(log_buf, true /*force*/);
for (j = 0; j <= i; j++) {
msg = &msgs->patterns[j];
fprintf(stderr, "%s %s: '%s'\n",
Expand Down Expand Up @@ -610,6 +646,37 @@ static bool should_do_test_run(struct test_spec *spec, struct test_subspec *subs
return true;
}

/* Get a disassembly of BPF program after verifier applies all rewrites */
static int get_xlated_program_text(int prog_fd, char *text, size_t text_sz)
{
struct bpf_insn *insn_start = NULL, *insn, *insn_end;
__u32 insns_cnt = 0, i;
char buf[64];
FILE *out = NULL;
int err;

err = get_xlated_program(prog_fd, &insn_start, &insns_cnt);
if (!ASSERT_OK(err, "get_xlated_program"))
goto out;
out = fmemopen(text, text_sz, "w");
if (!ASSERT_OK_PTR(out, "open_memstream"))
goto out;
insn_end = insn_start + insns_cnt;
insn = insn_start;
while (insn < insn_end) {
i = insn - insn_start;
insn = disasm_insn(insn, buf, sizeof(buf));
fprintf(out, "%d: %s\n", i, buf);
}
fflush(out);

out:
free(insn_start);
if (out)
fclose(out);
return err;
}

/* this function is forced noinline and has short generic name to look better
* in test_progs output (in case of a failure)
*/
Expand Down Expand Up @@ -695,7 +762,16 @@ void run_subtest(struct test_loader *tester,
}
}
emit_verifier_log(tester->log_buf, false /*force*/);
validate_msgs(tester->log_buf, &subspec->expect_msgs);
validate_msgs(tester->log_buf, &subspec->expect_msgs, emit_verifier_log);

if (subspec->expect_xlated.cnt) {
err = get_xlated_program_text(bpf_program__fd(tprog),
tester->log_buf, tester->log_buf_sz);
if (err)
goto tobj_cleanup;
emit_xlated(tester->log_buf, false /*force*/);
validate_msgs(tester->log_buf, &subspec->expect_xlated, emit_xlated);
}

if (should_do_test_run(spec, subspec)) {
/* For some reason test_verifier executes programs
Expand Down

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