First commit

Signed-off-by: Mattias Andrée <maandree@kth.se>

6 files changed, 280 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c48cd59
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+*\#*
+*~
+*.o
+*.su
+/asroot
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..c44b2d9
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,15 @@
+ISC License
+
+© 2021 Mattias Andrée <maandree@kth.se>
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..9bbde8c
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,29 @@
+.POSIX:
+
+CONFIGFILE = config.mk
+include $(CONFIGFILE)
+
+all: asroot
+asroot.o: asroot.c arg.h
+
+asroot: asroot.o
+	$(CC) -o $@ asroot.o $(LDFLAGS)
+
+install: asroot
+	mkdir -p -- "$(DESTDIR)$(PREFIX)/bin/"
+	mkdir -p -- "$(DESTDIR)$(MANPREFIX)/man8/"
+	cp -- asroot "$(DESTDIR)$(PREFIX)/bin/asroot"
+	cp -- asroot.8 "$(DESTDIR)$(MANPREFIX)/man8/asroot.8"
+
+post-install:
+	chown -- 'root:wheel' "$(DESTDIR)$(PREFIX)/bin/asroot"
+	chmod -- 4750 "$(DESTDIR)$(PREFIX)/bin/asroot"
+
+uninstall:
+	-rm -f -- "$(DESTDIR)$(PREFIX)/bin/asroot"
+	-rm -f -- "$(DESTDIR)$(MANPREFIX)/man8/asroot.8"
+
+clean:
+	-rm -f -- asroot.o asroot
+
+.PHONY: all install post-install uninstall clean
diff --git a/arg.h b/arg.h
new file mode 100644
index 0000000..4f7b6c0
--- /dev/null
+++ b/arg.h
@@ -0,0 +1,45 @@
+/*
+ * Copy me if you can.
+ * by 20h
+ */
+
+#ifndef ARG_H__
+#define ARG_H__
+
+extern char *argv0;
+
+/* use main(int argc, char *argv[]) */
+#define ARGBEGIN	for (argv0 = *argv, argv++, argc--;\
+					argv[0] && argv[0][0] && argv[0][1];\
+					argc--, argv++) {\
+				char argc_;\
+				char **argv_;\
+				int brk_;\
+				if (argv[0][0] == '-') {\
+					if (argv[0][1] == '-' && argv[0][2] == '\0') {\
+						argv++;\
+						argc--;\
+						break;\
+					}\
+					for (brk_ = 0, argv[0]++, argv_ = argv;\
+							argv[0][0] && !brk_;\
+							argv[0]++) {\
+						if (argv_ != argv)\
+							break;\
+						argc_ = argv[0][0];\
+						switch (argc_)
+
+#define ARGEND				}\
+				} else {\
+					break;\
+				}\
+			}
+
+#define EARGF(x)	((argv[0][1] == '\0' && argv[1] == NULL)?\
+				((x), abort(), (char *)0) :\
+				(brk_ = 1, (argv[0][1] != '\0')?\
+					(&argv[0][1]) :\
+					(argc--, argv++, argv[0])))
+
+
+#endif
diff --git a/asroot.c b/asroot.c
new file mode 100644
index 0000000..5f03b42
--- /dev/null
+++ b/asroot.c
@@ -0,0 +1,180 @@
+#include <errno.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "arg.h"
+
+
+char *argv0;
+
+extern char **environ;
+
+static const char *env_whitelist[] = {
+	"DISPLAY=",
+	"WAYLAND_DISPLAY=",
+	"PATH=",
+	"TERM=",
+	"COLORTERM=",
+	"XAUTHORITY=",
+	"LANG=",
+	"LANGUAGE=",
+	"LOCALE=",
+	"LC_CTYPE=",
+	"LC_NUMERIC=",
+	"LC_TIME=",
+	"LC_COLLATE=",
+	"LC_MONETARY=",
+	"LC_MESSAGES=",
+	"LC_PAPER=",
+	"LC_NAME=",
+	"LC_ADDRESS=",
+	"LC_TELEPHONE=",
+	"LC_MEASUREMENT=",
+	"LC_IDENTIFICATION=",
+	"LC_ALL=",
+	"LOCPATH=",
+	"NLSPATH=",
+	"TZ=",
+	"TZDIR=",
+	"SDL_VIDEO_FULLSCREEN_DISPLAY=",
+	"EDITOR=",
+	"VISUAL=",
+	"BROWSER=",
+	"DESKTOP_SESSION=",
+	"LS_COLORS=",
+	"GTK_THEME=",
+	"QT_STYLE_OVERRIDE=",
+	"PWD=",
+	"OLDPWD=",
+	"JAVA_HOME=",
+	"_JAVA_AWT_WM_NONREPARENTING=",
+	"_JAVA_OPTIONS=",
+	"MAIN_ALSA_MIXER=",
+	"MAIN_ALSA_CARD=",
+	"XDG_SEAT=",
+	"XDG_SESSION_TYPE=",
+	"XDG_SESSION_CLASS=",
+	"XDG_VTNR=",
+	"XDG_SESSION_ID=",
+	"XDG_DATA_DIRS=",
+	"XDG_CONFIG_DIRS=",
+	"MANPATH=",
+	"INFODIR=",
+	"PAGER=",
+	"ftp_proxy=",
+	"http_proxy=",
+	NULL
+};
+
+
+static void
+usage(void)
+{
+	fprintf(stderr, "usage: %s [-e] command [argument] ...\n", argv0);
+	exit(125);
+}
+
+
+int
+main(int argc, char *argv[])
+{
+	int keep_env = 0;
+	char **new_environ = NULL;
+	size_t i, j, n, len;
+	struct passwd *pw;
+
+	ARGBEGIN {
+	case 'e':
+		keep_env = 1;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (!argc)
+		usage();
+
+	/* TODO check password */
+
+	if (setgid(0)) {
+		fprintf(stderr, "%s: setgid 0: %s\n", argv0, strerror(errno));
+		return 125;
+	}
+	if (setuid(0)) {
+		fprintf(stderr, "%s: setuid 0: %s\n", argv0, strerror(errno));
+		return 125;
+	}
+
+	if (!keep_env) {
+		new_environ = calloc(sizeof(env_whitelist) / sizeof(*env_whitelist) + 5, sizeof(*env_whitelist));
+		if (!new_environ) {
+			fprintf(stderr, "%s: calloc %zu %zu: %s\n",
+			        argv0, sizeof(env_whitelist) / sizeof(*env_whitelist) + 5, sizeof(*env_whitelist), strerror(errno));
+			return errno == ENOENT ? 127 : 126;
+		}
+		for (i = 0, n = 0; env_whitelist[i]; i++) {
+			len = strlen(env_whitelist[i]);
+			for (j = 0; environ[j]; j++) {
+				if (!strncmp(environ[j], env_whitelist[i], len)) {
+					new_environ[n++] = environ[j];
+					break;
+				}
+			}
+		}
+		errno = 0;
+		pw = getpwuid(0);
+		if (!pw) {
+			if (errno)
+				fprintf(stderr, "%s: getpwuid 0: %s\n", argv0, strerror(errno));
+			else
+				fprintf(stderr, "%s: cannot find root user\n", argv0);
+			exit(125);
+		}
+		if (pw->pw_dir && *pw->pw_dir) {
+			len = strlen(pw->pw_dir);
+			len += sizeof("HOME=");
+			new_environ[n] = malloc(len);
+			if (!new_environ[n])
+				fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno));
+			stpcpy(stpcpy(new_environ[n++], "HOME="), pw->pw_dir);
+		}
+		if (pw->pw_name && *pw->pw_name) {
+			len = strlen(pw->pw_name);
+			len += sizeof("LOGNAME=");
+			new_environ[n] = malloc(len);
+			if (!new_environ[n])
+				fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno));
+			stpcpy(stpcpy(new_environ[n++], "LOGNAME="), pw->pw_name);
+
+			len -= sizeof("LOGNAME=");
+			len += sizeof("USER=");
+			new_environ[n] = malloc(len);
+			if (!new_environ[n])
+				fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno));
+			stpcpy(stpcpy(new_environ[n++], "USER="), pw->pw_name);
+
+			len -= sizeof("USER=");
+			len += sizeof("MAIL=/var/spool/mail/");
+			new_environ[n] = malloc(len);
+			if (!new_environ[n])
+				fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno));
+			stpcpy(stpcpy(new_environ[n++], "MAIL=/var/spool/mail/"), pw->pw_name);
+		}
+		if (pw->pw_shell && *pw->pw_shell) {
+			len = strlen(pw->pw_dir);
+			len += sizeof("SHELL=");
+			new_environ[n] = malloc(len);
+			if (!new_environ[n])
+				fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno));
+			stpcpy(stpcpy(new_environ[n++], "SHELL="), pw->pw_dir);
+		}
+		new_environ[n] = NULL;
+	}
+
+	execvpe(argv[0], argv, new_environ ? new_environ : environ);
+	fprintf(stderr, "%s: execvpe %s: %s\n", argv0, argv[0], strerror(errno));
+	return errno == ENOENT ? 127 : 126;
+}
diff --git a/config.mk b/config.mk
new file mode 100644
index 0000000..1f3b2b5
--- /dev/null
+++ b/config.mk
@@ -0,0 +1,6 @@
+PREFIX    = /usr
+MANPREFIX = $(PREFIX)/share/man
+
+CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=700 -D_GNU_SOURCE
+CFLAGS   = -std=c99 -Wall -O2 $(CPPFLAGS)
+LDFLAGS  = -s