101 lines
2.2 KiB
C
101 lines
2.2 KiB
C
#define _XOPEN_SOURCE // for crypt
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#include <pwd.h>
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#include <shadow.h>
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#include <stdbool.h>
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#include <sys/types.h>
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#include <unistd.h>
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#ifdef __GLIBC__
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// GNU, you damn slimy bastard
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#include <crypt.h>
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#endif
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#include "comm.h"
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#include "log.h"
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#include "swaylock.h"
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void initialize_pw_backend(int argc, char **argv) {
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if (geteuid() != 0) {
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swaylock_log(LOG_ERROR,
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"swaylock needs to be setuid to read /etc/shadow");
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exit(EXIT_FAILURE);
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}
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if (!spawn_comm_child()) {
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exit(EXIT_FAILURE);
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}
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if (setgid(getgid()) != 0) {
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swaylock_log_errno(LOG_ERROR, "Unable to drop root");
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exit(EXIT_FAILURE);
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}
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if (setuid(getuid()) != 0) {
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swaylock_log_errno(LOG_ERROR, "Unable to drop root");
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exit(EXIT_FAILURE);
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}
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if (setuid(0) != -1) {
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swaylock_log_errno(LOG_ERROR, "Unable to drop root (we shouldn't be "
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"able to restore it after setuid)");
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exit(EXIT_FAILURE);
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}
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}
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void run_pw_backend_child(void) {
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/* This code runs as root */
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struct passwd *pwent = getpwuid(getuid());
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if (!pwent) {
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swaylock_log_errno(LOG_ERROR, "failed to getpwuid");
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exit(EXIT_FAILURE);
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}
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char *encpw = pwent->pw_passwd;
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if (strcmp(encpw, "x") == 0) {
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struct spwd *swent = getspnam(pwent->pw_name);
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if (!swent) {
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swaylock_log_errno(LOG_ERROR, "failed to getspnam");
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exit(EXIT_FAILURE);
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}
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encpw = swent->sp_pwdp;
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}
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/* We don't need any additional logging here because the parent process will
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* also fail here and will handle logging for us. */
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if (setgid(getgid()) != 0) {
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exit(EXIT_FAILURE);
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}
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if (setuid(getuid()) != 0) {
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exit(EXIT_FAILURE);
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}
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if (setuid(0) != -1) {
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exit(EXIT_FAILURE);
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}
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/* This code does not run as root */
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swaylock_log(LOG_DEBUG, "Prepared to authorize user %s", pwent->pw_name);
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while (1) {
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char *buf;
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ssize_t size = read_comm_request(&buf);
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if (size < 0) {
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exit(EXIT_FAILURE);
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} else if (size == 0) {
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break;
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}
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char *c = crypt(buf, encpw);
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if (c == NULL) {
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swaylock_log_errno(LOG_ERROR, "crypt failed");
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clear_buffer(buf, size);
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exit(EXIT_FAILURE);
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}
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bool success = strcmp(c, encpw) == 0;
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if (!write_comm_reply(success)) {
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clear_buffer(buf, size);
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exit(EXIT_FAILURE);
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}
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clear_buffer(buf, size);
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free(buf);
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}
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clear_buffer(encpw, strlen(encpw));
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exit(EXIT_SUCCESS);
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} |