procdump

commit d9d200dbe38f62844e5ddb885e1778a888669c18
Author: Louis Burda <quent.burda@gmail.com>
Date:   Fri, 10 May 2024 05:10:00 +0200

Add initial version

Diffstat:
A
.gitignore
 | 
1
+
A
Makefile
 | 
24
++++++++++++++++++++++++
A
procdump.c
 | 
187
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

3 files changed, 212 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1 @@
+procdump
diff --git a/Makefile b/Makefile
@@ -0,0 +1,24 @@
+PREFIX ?= /usr/local
+BINDIR ?= /bin
+
+ifeq ($(DEBUG),1)
+CFLAGS = -Og -g
+else
+CFLAGS = -O3
+endif
+
+all: procdump
+
+procdump: procdump.c
+	gcc -o $@ $< $(CFLAGS)
+
+clean:
+	rm -f procdump
+
+install:
+	install -m755 procdump -t "$(DESTDIR)$(PREFIX)$(BINDIR)"
+
+uninstall:
+	rm -f "$(DESTDIR)$(PREFIX)$(BINDIR)/procdump"
+
+.PHONY: all install uninstall
diff --git a/procdump.c b/procdump.c
@@ -0,0 +1,187 @@
+#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);
+}