procdump

procdump.c (4276B)

#include <asm-generic/errno-base.h>
#include <linux/limits.h>
#include <sys/stat.h>
#include <sys/signal.h>
#include <libgen.h>
#include <unistd.h>
#include <pwd.h>

#include <errno.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include <stdint.h>
#include <stdbool.h>

#define _STR(x) #x
#define STR(x) _STR(x)

static pid_t pid = -1;

void
__attribute__((format(printf, 1, 2)))
die(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	fprintf(stderr, "procdump: ");
	vfprintf(stderr, fmt, ap);
	if (*fmt && fmt[strlen(fmt)-1] == ':') {
		fputc(' ', stderr);
		perror(NULL);
	} else {
		fputc('\n', stderr);
	}
	va_end(ap);
	exit(1);
}

void
dump(const char *dir, pid_t pid)
{
	char *path = malloc(PATH_MAX+1);
	if (!path) die("malloc:");

	char *lib = malloc(PATH_MAX+1);
	if (!lib) die("malloc:");

	if (setreuid(geteuid(), getuid()) || setregid(getegid(), getgid()))
		die("setreuid / setregid:");

	snprintf(path, PATH_MAX+1, "/proc/%i/maps", pid);
	FILE *maps = fopen(path, "r");
	if (!maps) die("fopen %s:", path);

	snprintf(path, PATH_MAX+1, "/proc/%i/mem", pid);
	FILE *mem = fopen(path, "r");
	if (!mem) die("fopen %s:", path);

	if (setreuid(geteuid(), getuid()) || setregid(getegid(), getgid()))
		die("setreuid / setregid:");

	snprintf(path, PATH_MAX+1, "%s/mem", dir);
	if (mkdir(path, 0755) && errno != EEXIST)
		die("mkdir %s", path);

	snprintf(path, PATH_MAX+1, "%s/maps", dir);
	if (mkdir(path, 0755) && errno != EEXIST)
		die("mkdir %s", path);

	ssize_t rc = 0;
	size_t linelen;
	char *line = NULL;
	while ((rc = getline(&line, &linelen, maps)) >= 0) {
		if (line[strlen(line)-1] == '\n')
			line[strlen(line)-1] = '\0';

		uint64_t start, end;
		char r, w, x, p;
		uint64_t offset;
		int n = sscanf(line, "%"PRIx64"-%"PRIx64" %c%c%c%c %"PRIx64
			" %*02u:%*02u %*u %"STR(PATH_MAX)"s",
			&start, &end, &r, &w, &x, &p, &offset, lib);
		if (n != 7 && n != 8) die("Bad line: %s", line);
		if (n == 7) *lib = '\0';

		if (end < start) die("Bad size: %s", line);
		uint64_t size = end - start;

		if (fseek(mem, start, SEEK_SET)) {
			fprintf(stderr, "procdump: Skipping '%s' at 0x%lx\n", lib, start);
			continue;
		}

		snprintf(path, PATH_MAX+1, "%s/mem/%016lx", dir, start);
		FILE *out = fopen(path, "w");
		if (!out) die("fopen %s:", path);
		char *buf = malloc(size);
		if (!buf) die("malloc:");
		if (fread(buf, size, 1, mem) != 1)
			fprintf(stderr, "procdump: Skipping '%s' at 0x%lx\n", lib, start);
		else if (fwrite(buf, size, 1, out) != 1)
			die("fwrite: %s", errno ? strerror(errno) : "trunc");
		free(buf);
		fclose(out);

		snprintf(path, PATH_MAX+1, "../../%s/mem/%016lx", dir, start);
		char *from = strdup(path);
		if (!from) die("strdup:");
		snprintf(path, PATH_MAX+1, "%s/maps/%s-%016lx-%c%c%c%c",
			dir, basename(lib), start, r, w, x, p);
		unlink(path);
		if (symlink(from, path)) die("symlink:");
		free(from);
	}
	free(line);

	fclose(maps);
	fclose(mem);
	free(path);
	free(lib);
}

void
unstop(void)
{
	int rc = kill(pid, SIGCONT);
	if (rc) die("Sending SIGCONT:");
}

int
main(int argc, const char **argv)
{
	const char **arg;
	char *end;

	if (!argc) return 1;

	const char *dir = NULL; 
	const char *unpriv = NULL;
	bool stop = false;
	for (arg = argv + 1; *arg; arg++) {
		if (!strcmp(*arg, "-s")) {
			stop = true;
		} else if (!strcmp(*arg, "-u")) {
			unpriv = *++arg;
		} else if (pid < 0) {
			pid = strtoul(*arg, &end, 10);
			if (!end || *end || pid > INT32_MAX)
				die("Bad pid: %s", *arg);
		} else if (!dir) {
			dir = *arg;
		} else {
			die("Invalid arg: %s", *arg);
		}
	}
	if (pid < 0) die("Usage: procdump [-s] PID [DIR]");

	if (stop) {
		int rc = kill(pid, SIGSTOP);
		if (rc) die("Sending SIGSTOP:");
		atexit(unstop);
	}

	if (unpriv) {
		struct passwd *pwd = calloc(1, sizeof(struct passwd));
		if (!pwd) die("calloc:");
		size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
		char *buf = malloc(buflen);
		if (!buf) die("malloc:");
		getpwnam_r(unpriv, pwd, buf, buflen, &pwd);
		if (!pwd) die("getpwnam_r %s:", unpriv);
		if (setegid(pwd->pw_gid)) die("setegid:");
		if (seteuid(pwd->pw_uid)) die("seteuid:");
	}

	if (!dir) {
		dir = ".";
	} else {
		if (mkdir(dir, 0755) && errno != EEXIST)
			die("mkdir %s", dir);
	}

	dump(dir, pid);
}