Merge pull request #123 from jasperla/bsdauth

Add support for bsd_auth(3) as authentication backend

6 files changed, 92 insertions, 46 deletions

diff --git a/Makefile b/Makefile
index b3d4dc2..3acb272 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,5 @@
 TOPDIR=$(shell pwd)
+UNAME=$(shell uname)
 
 INSTALL=install
 PREFIX=/usr
@@ -16,10 +17,14 @@ CFLAGS += -Wall
 CPPFLAGS += -D_GNU_SOURCE
 CFLAGS += $(shell $(PKG_CONFIG) --cflags cairo xcb-composite xcb-xinerama xcb-atom xcb-image xcb-xkb xkbcommon xkbcommon-x11)
 LIBS += $(shell $(PKG_CONFIG) --libs cairo xcb-composite xcb-xinerama xcb-atom xcb-image xcb-xkb xkbcommon xkbcommon-x11)
-LIBS += -lpam
 LIBS += -lev
 LIBS += -lm
 
+# OpenBSD lacks PAM, use bsd_auth(3) instead.
+ifneq ($(UNAME),OpenBSD)
+  LIBS += -lpam
+endif
+
 FILES:=$(wildcard *.c)
 FILES:=$(FILES:.c=.o)
 
diff --git a/README.md b/README.md
index fcecbfa..fc486b2 100644
--- a/README.md
+++ b/README.md
@@ -16,6 +16,7 @@ Many little improvements have been made to i3lock over time:
 - You can specify whether i3lock should bell upon a wrong password.
 
 - i3lock uses PAM and therefore is compatible with LDAP etc.
+  On OpenBSD i3lock uses the bsd_auth(3) framework.
 
 Requirements
 ------------
@@ -37,6 +38,9 @@ Running i3lock
 Simply invoke the 'i3lock' command. To get out of it, enter your password and
 press enter.
 
+On OpenBSD the `i3lock` binary needs to be setgid `auth` to call the
+authentication helpers, e.g. `/usr/libexec/auth/login_passwd`.
+
 Upstream
 --------
 Please submit pull requests to https://github.com/i3/i3lock
diff --git a/i3lock.c b/i3lock.c
index 761ed32..01f0436 100644
--- a/i3lock.c
+++ b/i3lock.c
@@ -18,7 +18,11 @@
 #include <xcb/xkb.h>
 #include <err.h>
 #include <assert.h>
+#ifdef __OpenBSD__
+#include <bsd_auth.h>
+#else
 #include <security/pam_appl.h>
+#endif
 #include <getopt.h>
 #include <string.h>
 #include <ev.h>
@@ -28,6 +32,9 @@
 #include <xkbcommon/xkbcommon-x11.h>
 #include <cairo.h>
 #include <cairo/cairo-xcb.h>
+#ifdef __OpenBSD__
+#include <strings.h> /* explicit_bzero(3) */
+#endif
 
 #include "i3lock.h"
 #include "xcb.h"
@@ -49,7 +56,9 @@ char color[7] = "ffffff";
 uint32_t last_resolution[2];
 xcb_window_t win;
 static xcb_cursor_t cursor;
+#ifndef __OpenBSD__
 static pam_handle_t *pam_handle;
+#endif
 int input_position = 0;
 /* Holds the password you enter (in UTF-8). */
 static char password[512];
@@ -59,11 +68,11 @@ bool unlock_indicator = true;
 char *modifier_string = NULL;
 static bool dont_fork = false;
 struct ev_loop *main_loop;
-static struct ev_timer *clear_pam_wrong_timeout;
+static struct ev_timer *clear_auth_wrong_timeout;
 static struct ev_timer *clear_indicator_timeout;
 static struct ev_timer *discard_passwd_timeout;
 extern unlock_state_t unlock_state;
-extern pam_state_t pam_state;
+extern auth_state_t auth_state;
 int failed_attempts = 0;
 bool show_failed_attempts = false;
 bool retry_verification = false;
@@ -158,6 +167,11 @@ static bool load_compose_table(const char *locale) {
  *
  */
 static void clear_password_memory(void) {
+#ifdef __OpenBSD__
+    /* Use explicit_bzero(3) which was explicitly designed not to be
+     * optimized out by the compiler. */
+    explicit_bzero(password, strlen(password));
+#else
     /* A volatile pointer to the password buffer to prevent the compiler from
      * optimizing this out. */
     volatile char *vpassword = password;
@@ -167,6 +181,7 @@ static void clear_password_memory(void) {
          * compiler from optimizing the calls away, since the value of 'beep'
          * is not known at compile-time. */
         vpassword[c] = c + (int)beep;
+#endif
 }
 
 ev_timer *start_timer(ev_timer *timer_obj, ev_tstamp timeout, ev_callback_t callback) {
@@ -206,13 +221,13 @@ static void finish_input(void) {
 }
 
 /*
- * Resets pam_state to STATE_PAM_IDLE 2 seconds after an unsuccessful
+ * Resets auth_state to STATE_AUTH_IDLE 2 seconds after an unsuccessful
  * authentication event.
  *
  */
-static void clear_pam_wrong(EV_P_ ev_timer *w, int revents) {
-    DEBUG("clearing pam wrong\n");
-    pam_state = STATE_PAM_IDLE;
+static void clear_auth_wrong(EV_P_ ev_timer *w, int revents) {
+    DEBUG("clearing auth wrong\n");
+    auth_state = STATE_AUTH_IDLE;
     redraw_screen();
 
     /* Clear modifier string. */
@@ -222,9 +237,9 @@ static void clear_pam_wrong(EV_P_ ev_timer *w, int revents) {
     }
 
     /* Now free this timeout. */
-    STOP_TIMER(clear_pam_wrong_timeout);
+    STOP_TIMER(clear_auth_wrong_timeout);
 
-    /* retry with input done during pam verification */
+    /* retry with input done during auth verification */
     if (retry_verification) {
         retry_verification = false;
         finish_input();
@@ -248,11 +263,24 @@ static void discard_passwd_cb(EV_P_ ev_timer *w, int revents) {
 }
 
 static void input_done(void) {
-    STOP_TIMER(clear_pam_wrong_timeout);
-    pam_state = STATE_PAM_VERIFY;
+    STOP_TIMER(clear_auth_wrong_timeout);
+    auth_state = STATE_AUTH_VERIFY;
     unlock_state = STATE_STARTED;
     redraw_screen();
 
+#ifdef __OpenBSD__
+    struct passwd *pw;
+
+    if (!(pw = getpwuid(getuid())))
+        errx(1, "unknown uid %u.", getuid());
+
+    if (auth_userokay(pw->pw_name, NULL, NULL, password) != 0) {
+        DEBUG("successfully authenticated\n");
+        clear_password_memory();
+
+        exit(0);
+    }
+#else
     if (pam_authenticate(pam_handle, 0) == PAM_SUCCESS) {
         DEBUG("successfully authenticated\n");
         clear_password_memory();
@@ -266,12 +294,13 @@ static void input_done(void) {
 
         exit(0);
     }
+#endif
 
     if (debug_mode)
         fprintf(stderr, "Authentication failure\n");
 
     /* Get state of Caps and Num lock modifiers, to be displayed in
-     * STATE_PAM_WRONG state */
+     * STATE_AUTH_WRONG state */
     xkb_mod_index_t idx, num_mods;
     const char *mod_name;
 
@@ -305,7 +334,7 @@ static void input_done(void) {
         }
     }
 
-    pam_state = STATE_PAM_WRONG;
+    auth_state = STATE_AUTH_WRONG;
     failed_attempts += 1;
     clear_input();
     if (unlock_indicator)
@@ -314,7 +343,7 @@ static void input_done(void) {
     /* Clear this state after 2 seconds (unless the user enters another
      * password during that time). */
     ev_now_update(main_loop);
-    START_TIMER(clear_pam_wrong_timeout, TSTAMP_N_SECS(2), clear_pam_wrong);
+    START_TIMER(clear_auth_wrong_timeout, TSTAMP_N_SECS(2), clear_auth_wrong);
 
     /* Cancel the clear_indicator_timeout, it would hide the unlock indicator
      * too early. */
@@ -393,7 +422,7 @@ static void handle_key_press(xcb_key_press_event_t *event) {
             if ((ksym == XKB_KEY_j || ksym == XKB_KEY_m) && !ctrl)
                 break;
 
-            if (pam_state == STATE_PAM_WRONG) {
+            if (auth_state == STATE_AUTH_WRONG) {
                 retry_verification = true;
                 return;
             }
@@ -597,6 +626,7 @@ void handle_screen_resize(void) {
     redraw_screen();
 }
 
+#ifndef __OpenBSD__
 /*
  * Callback function for PAM. We only react on password request callbacks.
  *
@@ -627,6 +657,7 @@ static int conv_callback(int num_msg, const struct pam_message **msg,
 
     return 0;
 }
+#endif
 
 /*
  * This callback is only a dummy, see xcb_prepare_cb and xcb_check_cb.
@@ -725,7 +756,7 @@ static void xcb_check_cb(EV_P_ ev_check *w, int revents) {
 /*
  * This function is called from a fork()ed child and will raise the i3lock
  * window when the window is obscured, even when the main i3lock process is
- * blocked due to PAM.
+ * blocked due to the authentication backend.
  *
  */
 static void raise_loop(xcb_window_t window) {
@@ -782,8 +813,10 @@ int main(int argc, char *argv[]) {
     struct passwd *pw;
     char *username;
     char *image_path = NULL;
+#ifndef __OpenBSD__
     int ret;
     struct pam_conv conv = {conv_callback, NULL};
+#endif
     int curs_choice = CURS_NONE;
     int o;
     int optind = 0;
@@ -877,17 +910,21 @@ int main(int argc, char *argv[]) {
      * the unlock indicator upon keypresses. */
     srand(time(NULL));
 
+#ifndef __OpenBSD__
     /* Initialize PAM */
     if ((ret = pam_start("i3lock", username, &conv, &pam_handle)) != PAM_SUCCESS)
         errx(EXIT_FAILURE, "PAM: %s", pam_strerror(pam_handle, ret));
 
     if ((ret = pam_set_item(pam_handle, PAM_TTY, getenv("DISPLAY"))) != PAM_SUCCESS)
         errx(EXIT_FAILURE, "PAM: %s", pam_strerror(pam_handle, ret));
+#endif
 
-/* Using mlock() as non-super-user seems only possible in Linux. Users of other
- * operating systems should use encrypted swap/no swap (or remove the ifdef and
- * run i3lock as super-user). */
-#if defined(__linux__)
+/* Using mlock() as non-super-user seems only possible in Linux and OpenBSD.
+ * Users of other operating systems should use encrypted swap/no swap
+ * (or remove the ifdef and run i3lock as super-user).
+ * NB: Alas, swap is encrypted by default on OpenBSD so swapping out
+ * is not necessarily an issue. */
+#if defined(__linux__) || defined(__OpenBSD__)
     /* Lock the area where we store the password in memory, we don’t want it to
      * be swapped to disk. Since Linux 2.6.9, this does not require any
      * privileges, just enough bytes in the RLIMIT_MEMLOCK limit. */
@@ -985,7 +1022,7 @@ int main(int argc, char *argv[]) {
     cursor = create_cursor(conn, screen, win, curs_choice);
 
     /* Display the "locking…" message while trying to grab the pointer/keyboard. */
-    pam_state = STATE_PAM_LOCK;
+    auth_state = STATE_AUTH_LOCK;
     grab_pointer_and_keyboard(conn, screen, cursor);
 
     pid_t pid = fork();
@@ -1012,7 +1049,7 @@ int main(int argc, char *argv[]) {
         errx(EXIT_FAILURE, "Could not initialize libev. Bad LIBEV_FLAGS?\n");
 
     /* Explicitly call the screen redraw in case "locking…" message was displayed */
-    pam_state = STATE_PAM_IDLE;
+    auth_state = STATE_AUTH_IDLE;
     redraw_screen();
 
     struct ev_io *xcb_watcher = calloc(sizeof(struct ev_io), 1);
diff --git a/unlock_indicator.c b/unlock_indicator.c
index ddad957..4c7d0e9 100644
--- a/unlock_indicator.c
+++ b/unlock_indicator.c
@@ -78,7 +78,7 @@ static xcb_visualtype_t *vistype;
 /* Maintain the current unlock/PAM state to draw the appropriate unlock
  * indicator. */
 unlock_state_t unlock_state;
-pam_state_t pam_state;
+auth_state_t auth_state;
 
 /*
  * Returns the scaling factor of the current screen. E.g., on a 227 DPI MacBook
@@ -141,7 +141,7 @@ xcb_pixmap_t draw_image(uint32_t *resolution) {
     }
 
     if (unlock_indicator &&
-        (unlock_state >= STATE_KEY_PRESSED || pam_state > STATE_PAM_IDLE)) {
+        (unlock_state >= STATE_KEY_PRESSED || auth_state > STATE_AUTH_IDLE)) {
         cairo_scale(ctx, scaling_factor(), scaling_factor());
         /* Draw a (centered) circle with transparent background. */
         cairo_set_line_width(ctx, 10.0);
@@ -154,12 +154,12 @@ xcb_pixmap_t draw_image(uint32_t *resolution) {
 
         /* Use the appropriate color for the different PAM states
          * (currently verifying, wrong password, or default) */
-        switch (pam_state) {
-            case STATE_PAM_VERIFY:
-            case STATE_PAM_LOCK:
+        switch (auth_state) {
+            case STATE_AUTH_VERIFY:
+            case STATE_AUTH_LOCK:
                 cairo_set_source_rgba(ctx, 0, 114.0 / 255, 255.0 / 255, 0.75);
                 break;
-            case STATE_PAM_WRONG:
+            case STATE_AUTH_WRONG:
             case STATE_I3LOCK_LOCK_FAILED:
                 cairo_set_source_rgba(ctx, 250.0 / 255, 0, 0, 0.75);
                 break;
@@ -169,16 +169,16 @@ xcb_pixmap_t draw_image(uint32_t *resolution) {
         }
         cairo_fill_preserve(ctx);
 
-        switch (pam_state) {
-            case STATE_PAM_VERIFY:
-            case STATE_PAM_LOCK:
+        switch (auth_state) {
+            case STATE_AUTH_VERIFY:
+            case STATE_AUTH_LOCK:
                 cairo_set_source_rgb(ctx, 51.0 / 255, 0, 250.0 / 255);
                 break;
-            case STATE_PAM_WRONG:
+            case STATE_AUTH_WRONG:
             case STATE_I3LOCK_LOCK_FAILED:
                 cairo_set_source_rgb(ctx, 125.0 / 255, 51.0 / 255, 0);
                 break;
-            case STATE_PAM_IDLE:
+            case STATE_AUTH_IDLE:
                 cairo_set_source_rgb(ctx, 51.0 / 255, 125.0 / 255, 0);
                 break;
         }
@@ -205,14 +205,14 @@ xcb_pixmap_t draw_image(uint32_t *resolution) {
         cairo_set_source_rgb(ctx, 0, 0, 0);
         cairo_select_font_face(ctx, "sans-serif", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
         cairo_set_font_size(ctx, 28.0);
-        switch (pam_state) {
-            case STATE_PAM_VERIFY:
+        switch (auth_state) {
+            case STATE_AUTH_VERIFY:
                 text = "verifying…";
                 break;
-            case STATE_PAM_LOCK:
+            case STATE_AUTH_LOCK:
                 text = "locking…";
                 break;
-            case STATE_PAM_WRONG:
+            case STATE_AUTH_WRONG:
                 text = "wrong!";
                 break;
             case STATE_I3LOCK_LOCK_FAILED:
@@ -245,7 +245,7 @@ xcb_pixmap_t draw_image(uint32_t *resolution) {
             cairo_close_path(ctx);
         }
 
-        if (pam_state == STATE_PAM_WRONG && (modifier_string != NULL)) {
+        if (auth_state == STATE_AUTH_WRONG && (modifier_string != NULL)) {
             cairo_text_extents_t extents;
             double x, y;
 
@@ -334,7 +334,7 @@ xcb_pixmap_t draw_image(uint32_t *resolution) {
  *
  */
 void redraw_screen(void) {
-    DEBUG("redraw_screen(unlock_state = %d, pam_state = %d)\n", unlock_state, pam_state);
+    DEBUG("redraw_screen(unlock_state = %d, auth_state = %d)\n", unlock_state, auth_state);
     xcb_pixmap_t bg_pixmap = draw_image(last_resolution);
     xcb_change_window_attributes(conn, win, XCB_CW_BACK_PIXMAP, (uint32_t[1]){bg_pixmap});
     /* XXX: Possible optimization: Only update the area in the middle of the
diff --git a/unlock_indicator.h b/unlock_indicator.h
index acfe768..2321620 100644
--- a/unlock_indicator.h
+++ b/unlock_indicator.h
@@ -11,12 +11,12 @@ typedef enum {
 } unlock_state_t;
 
 typedef enum {
-    STATE_PAM_IDLE = 0,          /* no PAM interaction at the moment */
-    STATE_PAM_VERIFY = 1,        /* currently verifying the password via PAM */
-    STATE_PAM_LOCK = 2,          /* currently locking the screen */
-    STATE_PAM_WRONG = 3,         /* the password was wrong */
+    STATE_AUTH_IDLE = 0,         /* no authenticator interaction at the moment */
+    STATE_AUTH_VERIFY = 1,       /* currently verifying the password via authenticator */
+    STATE_AUTH_LOCK = 2,         /* currently locking the screen */
+    STATE_AUTH_WRONG = 3,        /* the password was wrong */
     STATE_I3LOCK_LOCK_FAILED = 4 /* i3lock failed to load */
-} pam_state_t;
+} auth_state_t;
 
 xcb_pixmap_t draw_image(uint32_t* resolution);
 void redraw_screen(void);
diff --git a/xcb.c b/xcb.c
index 73ebb7e..078ddb9 100644
--- a/xcb.c
+++ b/xcb.c
@@ -24,7 +24,7 @@
 #include "cursors.h"
 #include "unlock_indicator.h"
 
-extern pam_state_t pam_state;
+extern auth_state_t auth_state;
 
 xcb_connection_t *conn;
 xcb_screen_t *screen;
@@ -262,7 +262,7 @@ void grab_pointer_and_keyboard(xcb_connection_t *conn, xcb_screen_t *screen, xcb
     /* After trying for 10000 times, i3lock will display an error message
      * for 2 sec prior to terminate. */
     if (tries <= 0) {
-        pam_state = STATE_I3LOCK_LOCK_FAILED;
+        auth_state = STATE_I3LOCK_LOCK_FAILED;
         redraw_screen();
         sleep(1);
         errx(EXIT_FAILURE, "Cannot grab pointer/keyboard");