Re-write program and add support for /etc/sus.

Signed-off-by: Slendi <slendi@socopon.com>

2 files changed, 177 insertions, 261 deletions

diff --git a/Makefile b/Makefile
index 69ddaa3..e986ce0 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 build:
-	cc -Wall -lcrypt -I. sus.c -o sus
+	tcc -lcrypt sus.c -o sus
 
 all: build install
 
diff --git a/sus.c b/sus.c
index df3512c..35eff58 100644
--- a/sus.c
+++ b/sus.c
@@ -1,286 +1,202 @@
 #define _GNU_SOURCE
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-
-#include <termios.h>
-
-#include <signal.h>
-
-#include <string.h>
-
+#include <crypt.h>
 #include <fcntl.h>
 #include <grp.h>
 #include <pwd.h>
 #include <shadow.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
 #include <sys/types.h>
+#include <termios.h>
+#include <unistd.h>
 
-#include <errno.h>
-
-#define MAX_PASSWORD 3
-
-void get_password(char* password);
-
-void cats(char** str, const char* str2);
-
-int CheckIfInGroup(const char* string);
-
-int GetUID(const char* username, uid_t* uid);
-void PrintHelp();
-void CreatePasswordMessage();
-
-int CheckPassword(char* password);
-int AskPassword();
-
-uid_t uid = 0;
-
-int command_start = 1;
-
-char* command_name;
-
-struct termios old_terminal;
-
-void getln(int, char*, size_t);
-
-struct passwd* pw;
-
-void intHandler(int dummy)
-{
-    tcsetattr(STDIN_FILENO, TCSANOW, &old_terminal);
-    puts("Cancelled.");
-    exit(0);
-}
-
-int main(int argc, char** argv, char** envp)
-{
-    uid = getuid();
-    pw = getpwuid(uid);
-
-    if (CheckIfInGroup("wheel") != 1) {
-        puts("ERROR: Not in the wheel group.");
-        return 0;
-    }
-
-    struct sigaction savealrm, saveint, savehup, savequit, saveterm;
-    struct sigaction savetstp, savettin, savettou, savepipe;
-
-    struct sigaction sa;
-    sigemptyset(&sa.sa_mask);
-    sa.sa_flags = 0;
-    sa.sa_handler = intHandler;
-
-    sigaction(SIGALRM, &sa, &savealrm);
-    sigaction(SIGHUP,  &sa, &savehup);
-    sigaction(SIGINT,  &sa, &saveint);
-    sigaction(SIGPIPE, &sa, &savepipe);
-    sigaction(SIGQUIT, &sa, &savequit);
-    sigaction(SIGTERM, &sa, &saveterm);
-    sigaction(SIGTSTP, &sa, &savetstp);
-    sigaction(SIGTTIN, &sa, &savettin);
-    sigaction(SIGTTOU, &sa, &savettou);
-
-    command_name = malloc((1 + strlen(argv[0])) * sizeof(char));
-    strcpy(command_name, argv[0]);
-
-    if (argc < 2) {
-        PrintHelp();
-        return 0;
-    }
-
-    if (AskPassword() != 1) {
-        puts("ERROR: Too many attempts.");
-        return 1;
-    }
-
-    char username[32];
-    username[0] = '\0';
-
-    if (argv[1][0] == '-') {
-        // - specified. Check if user is in next argument or
-        // in the same argument as the switch.
-        if (strlen(argv[1]) > 1) {
-            if (strlen(argv[1]) > 34) {
-                puts("ERROR: Username limit reached!");
-                return 1;
-            }
-            strcpy(username, argv[1]);
-            command_start = 2;
-        } else {
-            if (strlen(argv[2]) > 33) {
-                puts("ERROR: Username limit reached!");
-                return 1;
-            }
-            strcpy(username, argv[2]);
-            command_start = 3;
-        }
-
-        if (username[0] == '-')
-            memmove(username, username + 1, strlen(username));
-    }
-
-    if (username[0] == '\0')
-        uid = 0;
-    else if (GetUID(username, &uid) == -1) {
-        printf("ERROR: Could not find username: %s", username);
-        return 1;
-    }
-
-    sigaction(SIGALRM, &sa, NULL);
-    sigaction(SIGHUP,  &sa, NULL);
-    sigaction(SIGINT,  &sa, NULL);
-    sigaction(SIGPIPE, &sa, NULL);
-    sigaction(SIGQUIT, &sa, NULL);
-    sigaction(SIGTERM, &sa, NULL);
-    sigaction(SIGTSTP, &sa, NULL);
-    sigaction(SIGTTIN, &sa, NULL);
-    sigaction(SIGTTOU, &sa, NULL);
-
-
-    argv += command_start;
-    setuid(uid);
-    execvpe(argv[0], argv, envp);
-
-    return 0;
-}
+#define MAX_IDS 100
+long long ids[MAX_IDS] = { 0 };
+size_t ids_len = 0;
 
-int GetUID(const char* username, uid_t* uid)
+read_ids()
 {
-    pw = getpwnam(username);
-    if (pw != NULL) {
-        *uid = pw->pw_uid;
-        return 1;
-    }
-
-    return -1;
+	FILE *f = fopen("/etc/sus", "r");
+	if (!f) return 0;
+	while (!feof(f))
+		fscanf(f, "%lld", &ids[ids_len++]);
+	if (ids_len == 0) return 0;
+	return 1;
 }
 
-int CheckIfInGroup(const char* string)
+check_password(pass_buf)
+char *pass_buf;
 {
-    int groups = getgroups(0, NULL);
-
-    gid_t list[groups];
-
-    int ngroups = getgroups(groups, list);
-
-    if (ngroups < 0)
-        return -1;
-
-    for (int i = 0; i < groups; i++) {
-        struct group* grp;
-        grp = getgrgid(list[i]);
-        if (grp == NULL)
-            return -1;
-        if (strcmp(grp->gr_name, "wheel") == 0)
-            return 1;
-    }
-
-    return -1;
+	struct spwd* shadow_entry;
+	struct passwd* pa;
+	char *p, *correct, *supplied, *salt;
+	pa = getpwuid(getuid());
+	
+	shadow_entry = getspnam(pa->pw_name);
+	if (shadow_entry == NULL)
+		return 2;
+	
+	supplied = crypt(pass_buf, shadow_entry->sp_pwdp);
+	if (supplied == NULL)
+		return 6;
+	return !!strcmp(supplied, shadow_entry->sp_pwdp);
 }
 
-void PrintHelp() { printf("Usage: %s [- user] command\n", command_name); }
-
-int AskPassword()
+int getting_pass = 0;
+ask_password()
 {
-    for (int i = 0; i < MAX_PASSWORD; i++) {
-        char password[BUFSIZ];
-        get_password(password);
-
-        int res = CheckPassword(password);
-        if (res == 0)
-            return 1;
-        else
-            CreatePasswordMessage();
-        sleep(1);
-    }
-
-    return 0;
+	getting_pass = 1;
+	int i = 3;
+	while (i--) {
+		char *pass_buf = getpass("Password: ");
+		if (!pass_buf || *pass_buf == '\0') {
+			i++;
+			continue;
+		}
+		int res = check_password(pass_buf);
+		memset(pass_buf, 0, strlen(pass_buf)-1);
+		if (res == 0) {
+			getting_pass = 0;
+			return 1;
+		} else
+		  fputs("Wrong password!\n", stderr);
+		sleep(1);
+	}
+	getting_pass = 0;
+	return 0;
 }
 
-int CheckPassword(char* password)
+int_handler()
 {
-    struct spwd* shadow_entry;
-    struct passwd* pa = getpwuid(getuid());
-    char *p, *correct, *supplied, *salt;
-    shadow_entry = getspnam(pa->pw_name);
-    if (shadow_entry == NULL)
-        return 2;
-    correct = shadow_entry->sp_pwdp;
-    salt = strdup(correct);
-    if (salt == NULL)
-        return 3;
-    p = strchr(salt + 1, '$');
-    if (p == NULL)
-        return 4;
-    p = strchr(p + 1, '$');
-    if (p == NULL)
-        return 5;
-    p[1] = 0;
-
-    supplied = crypt(password, salt);
-    if (supplied == NULL)
-        return 6;
-    return !!strcmp(supplied, correct);
+	if (getting_pass)
+		return;
+	fputs("Cancelled.\n", stderr);
+	exit(0);
 }
 
-void CreatePasswordMessage() { puts("Incorrect password! Try again."); }
-
-void cats(char** str, const char* str2)
+is_valid()
 {
-    char* tmp = NULL;
-
-    // Reset *str
-    if (*str != NULL && str2 == NULL) {
-        free(*str);
-        *str = NULL;
-        return;
-    }
-
-    // Initial copy
-    if (*str == NULL) {
-        *str = calloc(strlen(str2) + 1, sizeof(char));
-        memcpy(*str, str2, strlen(str2));
-    } else { // Append
-        tmp = calloc(strlen(*str) + 1, sizeof(char));
-        memcpy(tmp, *str, strlen(*str));
-        *str = calloc(strlen(*str) + strlen(str2) + 1, sizeof(char));
-        memcpy(*str, tmp, strlen(tmp));
-        memcpy(*str + strlen(*str), str2, strlen(str2));
-        free(tmp);
-    }
+	int i, j, groups = getgroups(0, NULL);
+	gid_t list[groups];
+	int ngroups = getgroups(groups, list);
+
+	if (ngroups < 0)
+		return -1;
+
+	for (i = 0; i < groups; i++) {
+		struct group* grp;
+		grp = getgrgid(list[i]);
+		if (grp == NULL)
+			return 0;
+
+		for (j = 0; j < ids_len; j++)
+			if (grp->gr_gid == ids[j])
+				return 1;
+	}
+	return 0;
 }
 
-void get_password(char* password)
+main(argc, argv, envp, cstart, uid)
+char **argv; char **envp;
+uid_t uid;
 {
-    static struct termios new_terminal;
-
-    int ttyfd = open("/dev/tty", O_RDWR);
-
-    tcgetattr(ttyfd, &old_terminal);
-
-    new_terminal = old_terminal;
-    new_terminal.c_lflag &= ~(ECHO);
-
-    tcsetattr(ttyfd, TCSAFLUSH, &new_terminal);
-
-    write(ttyfd, "Password: ", 11);
-
-    getln(ttyfd, password, sizeof(password));
-
-    tcsetattr(ttyfd, TCSAFLUSH, &old_terminal);
-
-    close(ttyfd);
-
-    putchar('\n');
+	cstart = 1;
+	uid = 0;
+	struct sigaction savealrm, saveint, savehup, savequit, saveterm;
+	struct sigaction savetstp, savettin, savettou, savepipe;
+	
+	struct sigaction sa;
+	sigemptyset(&sa.sa_mask);
+	sa.sa_flags = 0;
+	sa.sa_handler = int_handler;
+	
+	sigaction(SIGALRM, &sa, &savealrm);
+	sigaction(SIGHUP,  &sa, &savehup);
+	sigaction(SIGINT,  &sa, &saveint);
+	sigaction(SIGPIPE, &sa, &savepipe);
+	sigaction(SIGQUIT, &sa, &savequit);
+	sigaction(SIGTERM, &sa, &saveterm);
+	sigaction(SIGTSTP, &sa, &savetstp);
+	sigaction(SIGTTIN, &sa, &savettin);
+	sigaction(SIGTTOU, &sa, &savettou);
+
+	if (argc < 2) {
+		fprintf(stderr, "Usage: %s [- user] -- command\n", argv[0]);
+		return 0;
+	}
+
+	if (strcmp(*(argv + cstart), "-") == 0) {
+		if (argc < 4) {
+			fprintf(stderr, "No command or user specified.\n");
+			return -1;
+		}
+
+		struct passwd *p = getpwnam(argv[2]);
+		if (!p) {
+			fprintf(stderr, "Invalid user specified.\n");
+			return -1;
+		}
+
+		uid = p->pw_uid;
+		char **envp2 = envp;
+		while (*envp2 != NULL) {
+			if (strncmp(*envp2, "USER=", 5) == 0) {
+				char *new_user_string = malloc(strlen(p->pw_name) + 6);
+				sprintf(new_user_string, "USER=%s", p->pw_name);
+				strcpy(*envp2, new_user_string);
+				free(new_user_string);
+				break;
+			}
+			envp2++;
+		}
+		cstart += 2;
+	}
+
+	if (strcmp(*(argv + cstart), "--") == 0) {
+		struct passwd *p = getpwuid(uid);
+		if (!p) {
+			fprintf(stderr, "UID not found, this should not happen.\n");
+			return -1;
+		}
+
+		chdir(p->pw_dir);
+		cstart++;
+		if (argc - cstart < 1) {
+			fprintf(stderr, "Command not found.\n");
+			return -1;
+		}
+	}
+
+	if (!read_ids()) {
+		fputs("Failed to read ids file /etc/sus.\n", stderr);
+		return -1;
+	}
+
+	if (!is_valid()) {
+		fputs("Not in the susers file, this incident won't be reported.\n", stderr);
+		return -1;
+	}
+
+	if (ask_password() != 1) {
+		fputs("Too many attempts.\n", stderr);
+		return -1;
+	}
+
+	sigaction(SIGALRM, &sa, NULL);
+	sigaction(SIGHUP,  &sa, NULL);
+	sigaction(SIGINT,  &sa, NULL);
+	sigaction(SIGPIPE, &sa, NULL);
+	sigaction(SIGQUIT, &sa, NULL);
+	sigaction(SIGTERM, &sa, NULL);
+	sigaction(SIGTSTP, &sa, NULL);
+	sigaction(SIGTTIN, &sa, NULL);
+	sigaction(SIGTTOU, &sa, NULL);
+	
+	argv += cstart;
+	setuid(uid);
+	execvpe(argv[0], argv, envp);
+
+	return 0;
 }
 
-void getln(int fd, char* buf, size_t bufsiz)
-{
-    ssize_t nr = -1;
-    char ch;
-    while ((nr = read(fd, &ch, 1)) == 1 && ch != '\n' && ch != '\r') {
-        if (buf < buf + bufsiz - 1) {
-            *buf++ = ch;
-        }
-    }
-    *buf = '\0';
-}