64259db8d6
This involves setuid'ing swaylock, which then forks and drops perms on the parent process. The child process remains root and listens on a pipe for requests to validate passwords against /etc/shadow.
63 lines
1.8 KiB
C
63 lines
1.8 KiB
C
#define _XOPEN_SOURCE 500
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#include <pwd.h>
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#include <security/pam_appl.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <wlr/util/log.h>
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#include "swaylock/swaylock.h"
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void initialize_pw_backend(void) {
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// TODO: only call pam_start once. keep the same handle the whole time
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}
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static int function_conversation(int num_msg, const struct pam_message **msg,
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struct pam_response **resp, void *data) {
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struct swaylock_password *pw = data;
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/* PAM expects an array of responses, one for each message */
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struct pam_response *pam_reply = calloc(
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num_msg, sizeof(struct pam_response));
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*resp = pam_reply;
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for (int i = 0; i < num_msg; ++i) {
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switch (msg[i]->msg_style) {
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case PAM_PROMPT_ECHO_OFF:
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case PAM_PROMPT_ECHO_ON:
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pam_reply[i].resp = strdup(pw->buffer); // PAM clears and frees this
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break;
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case PAM_ERROR_MSG:
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case PAM_TEXT_INFO:
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break;
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}
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}
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return PAM_SUCCESS;
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}
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bool attempt_password(struct swaylock_password *pw) {
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struct passwd *passwd = getpwuid(getuid());
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char *username = passwd->pw_name;
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const struct pam_conv local_conversation = {
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function_conversation, pw
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};
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pam_handle_t *local_auth_handle = NULL;
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int pam_err;
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if ((pam_err = pam_start("swaylock", username,
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&local_conversation, &local_auth_handle)) != PAM_SUCCESS) {
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wlr_log(WLR_ERROR, "PAM returned error %d", pam_err);
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}
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if ((pam_err = pam_authenticate(local_auth_handle, 0)) != PAM_SUCCESS) {
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wlr_log(WLR_ERROR, "pam_authenticate failed");
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goto fail;
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}
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// TODO: only call pam_end once we succeed at authing. refresh tokens beforehand
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if ((pam_err = pam_end(local_auth_handle, pam_err)) != PAM_SUCCESS) {
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wlr_log(WLR_ERROR, "pam_end failed");
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goto fail;
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}
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clear_password_buffer(pw);
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return true;
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fail:
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clear_password_buffer(pw);
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return false;
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}
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