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#undef _POSIX_C_SOURCE
#define _XOPEN_SOURCE // for crypt
#include <assert.h>
#include <pwd.h>
#include <shadow.h>
#include <stdlib.h>
#include <stdbool.h>
#include <sys/types.h>
#include <unistd.h>
#ifdef __GLIBC__
// GNU, you damn slimy bastard
#include <crypt.h>
#endif
#include "comm.h"
#include "log.h"
#include "password-buffer.h"
#include "swaylock.h"
char *encpw = NULL;
void initialize_pw_backend(int argc, char **argv) {
/* This code runs as root */
struct passwd *pwent = getpwuid(getuid());
if (!pwent) {
swaylock_log_errno(LOG_ERROR, "failed to getpwuid");
exit(EXIT_FAILURE);
}
encpw = pwent->pw_passwd;
if (strcmp(encpw, "x") == 0) {
struct spwd *swent = getspnam(pwent->pw_name);
if (!swent) {
swaylock_log_errno(LOG_ERROR, "failed to getspnam");
exit(EXIT_FAILURE);
}
encpw = swent->sp_pwdp;
}
if (setgid(getgid()) != 0) {
swaylock_log_errno(LOG_ERROR, "Unable to drop root");
exit(EXIT_FAILURE);
}
if (setuid(getuid()) != 0) {
swaylock_log_errno(LOG_ERROR, "Unable to drop root");
exit(EXIT_FAILURE);
}
if (setuid(0) != -1 || setgid(0) != -1) {
swaylock_log_errno(LOG_ERROR, "Unable to drop root (we shouldn't be "
"able to restore it after setuid/setgid)");
exit(EXIT_FAILURE);
}
/* This code does not run as root */
swaylock_log(LOG_DEBUG, "Prepared to authorize user %s", pwent->pw_name);
if (!spawn_comm_child()) {
exit(EXIT_FAILURE);
}
/* Buffer is only used by the child */
clear_buffer(encpw, strlen(encpw));
encpw = NULL;
}
void run_pw_backend_child(void) {
assert(encpw != NULL);
while (1) {
char *buf;
ssize_t size = read_comm_request(&buf);
if (size < 0) {
exit(EXIT_FAILURE);
} else if (size == 0) {
break;
}
const char *c = crypt(buf, encpw);
password_buffer_destroy(buf, size);
buf = NULL;
if (c == NULL) {
swaylock_log_errno(LOG_ERROR, "crypt failed");
exit(EXIT_FAILURE);
}
bool success = strcmp(c, encpw) == 0;
if (!write_comm_reply(success)) {
exit(EXIT_FAILURE);
}
sleep(2);
}
clear_buffer(encpw, strlen(encpw));
exit(EXIT_SUCCESS);
}
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