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execsnoop.c
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execsnoop.c
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// Based on execsnoop(8) from BCC by Brendan Gregg and others.
//
#include <argp.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
#include <bpf/libbpf.h>
#include <bpf/bpf.h>
#include "execsnoop.h"
#include "execsnoop.skel.h"
#include "trace_helpers.h"
#define PERF_BUFFER_PAGES 64
#define NSEC_PRECISION (NSEC_PER_SEC / 1000)
#define MAX_ARGS_KEY 259
static struct env {
bool time;
bool timestamp;
bool fails;
uid_t uid;
bool quote;
const char *name;
const char *line;
bool print_uid;
bool verbose;
int max_args;
} env = {
.max_args = DEFAULT_MAXARGS,
.uid = INVALID_UID
};
static struct timespec start_time;
const char *argp_program_version = "execsnoop 0.1";
const char *argp_program_bug_address = "<[email protected]>";
const char argp_program_doc[] =
"Trace open family syscalls\n"
"\n"
"USAGE: execsnoop [-h] [-T] [-t] [-x] [-u UID] [-q] [-n NAME] [-l LINE] [-U]\n"
" [--max-args MAX_ARGS]\n"
"\n"
"EXAMPLES:\n"
" ./execsnoop # trace all exec() syscalls\n"
" ./execsnoop -x # include failed exec()s\n"
" ./execsnoop -T # include time (HH:MM:SS)\n"
" ./execsnoop -U # include UID\n"
" ./execsnoop -u 1000 # only trace UID 1000\n"
" ./execsnoop -t # include timestamps\n"
" ./execsnoop -q # add \"quotemarks\" around arguments\n"
" ./execsnoop -n main # only print command lines containing \"main\"\n"
" ./execsnoop -l tpkg # only print command where arguments contains \"tpkg\"";
static const struct argp_option opts[] = {
{ "time", 'T', NULL, 0, "include time column on output (HH:MM:SS)"},
{ "timestamp", 't', NULL, 0, "include timestamp on output"},
{ "fails", 'x', NULL, 0, "include failed exec()s"},
{ "uid", 'u', "UID", 0, "trace this UID only"},
{ "quote", 'q', NULL, 0, "Add quotemarks (\") around arguments"},
{ "name", 'n', "NAME", 0, "only print commands matching this name, any arg"},
{ "line", 'l', "LINE", 0, "only print commands where arg contains this line"},
{ "print-uid", 'U', NULL, 0, "print UID column"},
{ "max-args", MAX_ARGS_KEY, "MAX_ARGS", 0,
"maximum number of arguments parsed and displayed, defaults to 20"},
{ "verbose", 'v', NULL, 0, "Verbose debug output" },
{},
};
static error_t parse_arg(int key, char *arg, struct argp_state *state)
{
long int uid, max_args;
switch (key) {
case 'h':
argp_usage(state);
break;
case 'T':
env.time = true;
break;
case 't':
env.timestamp = true;
break;
case 'x':
env.fails = true;
break;
case 'u':
errno = 0;
uid = strtol(arg, NULL, 10);
if (errno || uid < 0 || uid >= INVALID_UID) {
fprintf(stderr, "Invalid UID %s\n", arg);
argp_usage(state);
}
env.uid = uid;
break;
case 'q':
env.quote = true;
break;
case 'n':
env.name = arg;
break;
case 'l':
env.line = arg;
break;
case 'U':
env.print_uid = true;
break;
case 'v':
env.verbose = true;
break;
case MAX_ARGS_KEY:
errno = 0;
max_args = strtol(arg, NULL, 10);
if (errno || max_args < 1 || max_args > TOTAL_MAX_ARGS) {
fprintf(stderr, "Invalid MAX_ARGS %s, should be in [1, %d] range\n",
arg, TOTAL_MAX_ARGS);
argp_usage(state);
}
env.max_args = max_args;
break;
default:
return ARGP_ERR_UNKNOWN;
}
return 0;
}
int libbpf_print_fn(enum libbpf_print_level level,
const char *format, va_list args)
{
if (level == LIBBPF_DEBUG && !env.verbose)
return 0;
return vfprintf(stderr, format, args);
}
static void time_since_start()
{
long nsec, sec;
static struct timespec cur_time;
double time_diff;
clock_gettime(CLOCK_MONOTONIC, &cur_time);
nsec = cur_time.tv_nsec - start_time.tv_nsec;
sec = cur_time.tv_sec - start_time.tv_sec;
if (nsec < 0) {
nsec += NSEC_PER_SEC;
sec--;
}
time_diff = sec + (double)nsec / NSEC_PER_SEC;
printf("%-8.3f", time_diff);
}
static void inline quoted_symbol(char c) {
switch(c) {
case '"':
putchar('\\');
putchar('"');
break;
case '\t':
putchar('\\');
putchar('t');
break;
case '\n':
putchar('\\');
putchar('n');
break;
default:
putchar(c);
break;
}
}
static void print_args(const struct event *e, bool quote)
{
int i, args_counter = 0;
if (env.quote)
putchar('"');
for (i = 0; i < e->args_size && args_counter < e->args_count; i++) {
char c = e->args[i];
if (env.quote) {
if (c == '\0') {
args_counter++;
putchar('"');
putchar(' ');
if (args_counter < e->args_count) {
putchar('"');
}
} else {
quoted_symbol(c);
}
} else {
if (c == '\0') {
args_counter++;
putchar(' ');
} else {
putchar(c);
}
}
}
if (e->args_count == env.max_args + 1) {
fputs(" ...", stdout);
}
}
void handle_event(void *ctx, int cpu, void *data, __u32 data_sz)
{
const struct event *e = data;
time_t t;
struct tm *tm;
char ts[32];
/* TODO: use pcre lib */
if (env.name && strstr(e->comm, env.name) == NULL)
return;
/* TODO: use pcre lib */
if (env.line && strstr(e->comm, env.line) == NULL)
return;
time(&t);
tm = localtime(&t);
strftime(ts, sizeof(ts), "%H:%M:%S", tm);
if (env.time) {
printf("%-8s ", ts);
}
if (env.timestamp) {
time_since_start();
}
if (env.print_uid)
printf("%-6d", e->uid);
printf("%-16s %-6d %-6d %3d ", e->comm, e->pid, e->ppid, e->retval);
print_args(e, env.quote);
putchar('\n');
}
void handle_lost_events(void *ctx, int cpu, __u64 lost_cnt)
{
fprintf(stderr, "Lost %llu events on CPU #%d!\n", lost_cnt, cpu);
}
int main(int argc, char **argv)
{
static const struct argp argp = {
.options = opts,
.parser = parse_arg,
.doc = argp_program_doc,
};
struct perf_buffer_opts pb_opts;
struct perf_buffer *pb = NULL;
struct execsnoop_bpf *obj;
int err;
err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
if (err)
return err;
libbpf_set_print(libbpf_print_fn);
err = bump_memlock_rlimit();
if (err) {
fprintf(stderr, "failed to increase rlimit: %d\n", err);
return 1;
}
obj = execsnoop_bpf__open();
if (!obj) {
fprintf(stderr, "failed to open BPF object\n");
return 1;
}
/* initialize global data (filtering options) */
obj->rodata->ignore_failed = !env.fails;
obj->rodata->targ_uid = env.uid;
obj->rodata->max_args = env.max_args;
err = execsnoop_bpf__load(obj);
if (err) {
fprintf(stderr, "failed to load BPF object: %d\n", err);
goto cleanup;
}
clock_gettime(CLOCK_MONOTONIC, &start_time);
err = execsnoop_bpf__attach(obj);
if (err) {
fprintf(stderr, "failed to attach BPF programs\n");
goto cleanup;
}
/* print headers */
if (env.time) {
printf("%-9s", "TIME");
}
if (env.timestamp) {
printf("%-8s ", "TIME(s)");
}
if (env.print_uid) {
printf("%-6s ", "UID");
}
printf("%-16s %-6s %-6s %3s %s\n", "PCOMM", "PID", "PPID", "RET", "ARGS");
/* setup event callbacks */
pb_opts.sample_cb = handle_event;
pb_opts.lost_cb = handle_lost_events;
pb = perf_buffer__new(bpf_map__fd(obj->maps.events), PERF_BUFFER_PAGES, &pb_opts);
err = libbpf_get_error(pb);
if (err) {
pb = NULL;
fprintf(stderr, "failed to open perf buffer: %d\n", err);
goto cleanup;
}
/* main: poll */
while ((err = perf_buffer__poll(pb, 100)) >= 0)
;
printf("Error polling perf buffer: %d\n", err);
cleanup:
perf_buffer__free(pb);
execsnoop_bpf__destroy(obj);
return err != 0;
}