naive implementation of sudo and possibly insecure setuid support

Makefile

@@ -220,10 +220,10 @@ $(foreach file,$(USER_CXXFILES),$(eval $(call user-cxx-rule,$(patsubst %.c++,hdd
 # Hard Disk Images #
 ####################
 
-toaruos-disk.img: ${USERSPACE} ${MODULES}
+toaruos-disk.img: ${USERSPACE} ${MODULES} util/devtable
 	@${BEG} "hdd" "Generating a Hard Disk image..."
 	@-rm -f toaruos-disk.img
-	@${GENEXT} -B 4096 -d hdd -U -b ${DISK_SIZE} -N 4096 toaruos-disk.img ${ERRORS}
+	@${GENEXT} -B 4096 -d hdd -D util/devtable -U -b ${DISK_SIZE} -N 4096 toaruos-disk.img ${ERRORS}
 	@${END} "hdd" "Generated Hard Disk image"
 	@${INFO} "--" "Hard disk image is ready!"
 

kernel/misc/elf.c

@@ -108,7 +108,6 @@ exec(
 
 	/* Free the space we used for the ELF headers and files */
 	free(header);
-	close_fs(file);
 
 	for (uintptr_t stack_pointer = USER_STACK_BOTTOM; stack_pointer < USER_STACK_TOP; stack_pointer += 0x1000) {
 		alloc_frame(get_page(stack_pointer, 1, current_directory), 0, 1);
@@ -173,6 +172,14 @@ exec(
 
 	current_process->image.start = entry;
 
+	/* XXX setuid */
+	if (file->mask & 0x800) {
+		debug_print(WARNING, "setuid binary executed [%s, uid:%d]", file->name, file->uid);
+		current_process->user = file->uid;
+	}
+
+	close_fs(file);
+
 	/* Go go go */
 	enter_user_jmp(entry, argc, argv_, USER_STACK_TOP);
 

userspace/core/ls.c

@@ -133,6 +133,8 @@ void print_entry_long(const char * filename, const char * srcpath) {
 	/* file permissions */
 	if (S_ISLNK(statbuf.st_mode)) {
 		printf("l");
+	} else if (statbuf.st_mode & S_ISUID) {
+		printf("s");
 	} else {
 		printf( (S_ISDIR(statbuf.st_mode))  ? "d" : "-");
 	}

userspace/core/sudo.c

@@ -0,0 +1,120 @@
+/* vim: tabstop=4 shiftwidth=4 noexpandtab
+ *
+ * sudo
+ *
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <syscall.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+#include <signal.h>
+#include <termios.h>
+#include <errno.h>
+#include <sys/wait.h>
+
+#include <sys/utsname.h>
+
+#include "lib/sha2.h"
+
+#define LINE_LEN 1024
+
+uint32_t child = 0;
+
+int checkUserPass(char * user, char * pass) {
+
+	/* Generate SHA512 */
+	char hash[SHA512_DIGEST_STRING_LENGTH];
+	SHA512_Data(pass, strlen(pass), hash);
+
+	/* Open up /etc/master.passwd */
+
+	FILE * passwd = fopen("/etc/master.passwd", "r");
+	char line[2048];
+
+	while (fgets(line, 2048, passwd) != NULL) {
+
+		line[strlen(line)-1] = '\0';
+
+		char *p, *tokens[4], *last;
+		int i = 0;
+		for ((p = strtok_r(line, ":", &last)); p;
+				(p = strtok_r(NULL, ":", &last)), i++) {
+			if (i < 511) tokens[i] = p;
+		}
+		tokens[i] = NULL;
+		
+		if (strcmp(tokens[0],user) != 0) {
+			continue;
+		}
+		if (!strcmp(tokens[1],hash)) {
+			fclose(passwd);
+			return atoi(tokens[2]);
+		}
+		}
+	fclose(passwd);
+	return -1;
+
+}
+
+void usage(int argc, char * argv[]) {
+	fprintf(stderr, "usage: %s [command]\n", argv[0]);
+}
+
+int main(int argc, char ** argv) {
+
+	int fails = 0;
+
+	if (argc < 2) {
+		usage(argc, argv);
+		return 1;
+	}
+
+	while (1) {
+		/*
+		 * This is not very secure, but I'm lazy and just want this to exist.
+		 * It's not like we have file system permissions or anything like
+		 * that sitting around anyway... So, XXX: make this not dumb.
+		 */
+		char * username = getenv("USER");
+		char * password = malloc(sizeof(char) * 1024);
+
+		fprintf(stdout, "[%s] password for %s: ", argv[0], username);
+		fflush(stdout);
+
+		/* Disable echo */
+		struct termios old, new;
+		tcgetattr(fileno(stdin), &old);
+		new = old;
+		new.c_lflag &= (~ECHO);
+		tcsetattr(fileno(stdin), TCSAFLUSH, &new);
+
+		fgets(password, 1024, stdin);
+		password[strlen(password)-1] = '\0';
+		tcsetattr(fileno(stdin), TCSAFLUSH, &old);
+		fprintf(stdout, "\n");
+
+		int uid = checkUserPass(username, password);
+
+		if (uid < 0) {
+			fails++;
+			if (fails == 3) {
+				fprintf(stderr, "%s: %d incorrect password attempts\n", argv[0]);
+				break;
+			}
+			fprintf(stderr, "Sorry, try again.\n");
+			continue;
+		}
+
+		char ** args = &argv[1];
+		int i = execvp(args[0], args);
+
+		/* XXX: There are other things that can cause an exec to fail. */
+		fprintf(stderr, "%s: %s: command not found\n", argv[0], args[0]);
+	}
+
+	return 1;
+}

util/devtable

@@ -0,0 +1 @@
+/bin/sudo f 4555 0 0 - - - - -