Display the lecture immediately before prompting for a password.

This means we no longer display the lecture unless the user is going
to enter a password.  Authentication methods that don't interact
with the user via the terminal don't trigger the lecture.

plugins/sudoers/auth/afs.c

@@ -42,6 +42,7 @@
 
 #include "sudoers.h"
 #include "sudo_auth.h"
+#include "check.h"
 
 int
 sudo_afs_verify(struct passwd *pw, char *pass, sudo_auth *auth, struct sudo_conv_callback *callback)
@@ -53,6 +54,9 @@ sudo_afs_verify(struct passwd *pw, char *pass, sudo_auth *auth, struct sudo_conv
     if (IS_NONINTERACTIVE(auth))
 	debug_return_int(AUTH_NONINTERACTIVE);
 
+    /* Display lecture if needed and we haven't already done so. */
+    display_lecture(callback);
+
     /* Try to just check the password */
     ka_StringToKey(pass, NULL, &afs_key);
     if (ka_GetAdminToken(pw->pw_name,		/* name */

plugins/sudoers/auth/dce.c

@@ -54,6 +54,7 @@
 
 #include "sudoers.h"
 #include "sudo_auth.h"
+#include "check.h"
 
 static int check_dce_status(error_status_t, char *);
 
@@ -71,6 +72,9 @@ sudo_dce_verify(struct passwd *pw, char *plain_pw, sudo_auth *auth, struct sudo_
     if (IS_NONINTERACTIVE(auth))
 	debug_return_int(AUTH_NONINTERACTIVE);
 
+    /* Display lecture if needed and we haven't already done so. */
+    display_lecture(callback);
+
     /*
      * Create the local context of the DCE principal necessary
      * to perform authenticated network operations.  The network

plugins/sudoers/auth/sudo_auth.c

@@ -44,6 +44,7 @@
 #include "sudoers.h"
 #include "sudo_auth.h"
 #include "insults.h"
+#include "check.h"
 
 static sudo_auth auth_switch[] = {
 /* Standalone entries first */
@@ -443,6 +444,9 @@ auth_getpass(const char *prompt, int type, struct sudo_conv_callback *callback)
     sigset_t mask, omask;
     debug_decl(auth_getpass, SUDOERS_DEBUG_AUTH);
 
+    /* Display lecture if needed and we haven't already done so. */
+    display_lecture(callback);
+
     /* Mask user input if pwfeedback set and echo is off. */
     if (type == SUDO_CONV_PROMPT_ECHO_OFF && def_pwfeedback)
 	type = SUDO_CONV_PROMPT_MASK;

plugins/sudoers/check.c

@@ -42,15 +42,15 @@
 #include "sudoers.h"
 #include "check.h"
 
-static bool display_lecture(int);
-static struct passwd *get_authpw(int);
-
 struct getpass_closure {
     int tstat;
+    int lectured;
     void *cookie;
     struct passwd *auth_pw;
 };
 
+static struct passwd *get_authpw(int);
+
 /*
  * Called when getpass is suspended so we can drop the lock.
  */
@@ -87,26 +87,30 @@ getpass_resume(int signo, void *vclosure)
 static int
 check_user_interactive(int validated, int mode, struct getpass_closure *closure)
 {
-    struct sudo_conv_callback cb, *callback = NULL;
+    struct sudo_conv_callback callback;
     int ret = -1;
     char *prompt;
-    bool lectured;
     debug_decl(check_user_interactive, SUDOERS_DEBUG_AUTH);
 
+    /* Construct callback for getpass function. */
+    memset(&callback, 0, sizeof(callback));
+    callback.version = SUDO_CONV_CALLBACK_VERSION;
+    callback.closure = closure;
+    callback.on_suspend = getpass_suspend;
+    callback.on_resume = getpass_resume;
+
     /* Open, lock and read time stamp file if we are using it. */
     if (!ISSET(mode, MODE_IGNORE_TICKET)) {
 	/* Open time stamp file and check its status. */
 	closure->cookie = timestamp_open(user_name, user_sid);
-	if (timestamp_lock(closure->cookie, closure->auth_pw))
+	if (closure->cookie != NULL) {
-	    closure->tstat = timestamp_status(closure->cookie, closure->auth_pw);
+	    if (timestamp_lock(closure->cookie, closure->auth_pw)) {
-
+		closure->tstat = timestamp_status(closure->cookie,
-	/* Construct callback for getpass function. */
+		    closure->auth_pw);
-	memset(&cb, 0, sizeof(cb));
+	    }
-	cb.version = SUDO_CONV_CALLBACK_VERSION;
+	    callback.on_suspend = getpass_suspend;
-	cb.closure = closure;
+	    callback.on_resume = getpass_resume;
-	cb.on_suspend = getpass_suspend;
+	}
-	cb.on_resume = getpass_resume;
-	callback = &cb;
     }
 
     switch (closure->tstat) {
@@ -131,17 +135,14 @@ check_user_interactive(int validated, int mode, struct getpass_closure *closure)
 	    goto done;
 	}
 
-	/* XXX - should not lecture if askpass helper is being used. */
-	lectured = display_lecture(closure->tstat);
-
 	/* Expand any escapes in the prompt. */
 	prompt = expand_prompt(user_prompt ? user_prompt : def_passprompt,
 	    closure->auth_pw->pw_name);
 	if (prompt == NULL)
 	    goto done;
 
-	ret = verify_user(closure->auth_pw, prompt, validated, callback);
+	ret = verify_user(closure->auth_pw, prompt, validated, &callback);
-	if (ret == true && lectured)
+	if (ret == true && closure->lectured)
 	    (void)set_lectured();	/* lecture error not fatal */
 	free(prompt);
 	break;
@@ -228,9 +229,10 @@ done:
  * Display sudo lecture (standard or custom).
  * Returns true if the user was lectured, else false.
  */
-static bool
+void
-display_lecture(int status)
+display_lecture(struct sudo_conv_callback *callback)
 {
+    struct getpass_closure *closure = callback->closure;
     struct sudo_conv_message msg;
     struct sudo_conv_reply repl;
     char buf[BUFSIZ];
@@ -239,9 +241,11 @@ display_lecture(int status)
     int fd;
     debug_decl(lecture, SUDOERS_DEBUG_AUTH);
 
-    if (def_lecture == never ||
+    if (closure->lectured)
-	(def_lecture == once && already_lectured(status)))
+	debug_return;
-	debug_return_bool(false);
+
+    if (def_lecture == never || (def_lecture == once && already_lectured()))
+	debug_return;
 
     memset(&msg, 0, sizeof(msg));
     memset(&repl, 0, sizeof(repl));
@@ -257,13 +261,12 @@ display_lecture(int status)
 		    msg.msg = buf;
 		    sudo_conv(1, &msg, &repl, NULL);
 		}
+		if (nread == 0) {
 		    close(fd);
-		if (nread == -1) {
+		    goto done;
+		}
 		log_warning(SLOG_RAW_MSG,
 		    N_("error reading lecture file %s"), def_lecture_file);
-		    debug_return_bool(false);
-		}
-		debug_return_bool(true);
 	    } else {
 		log_warningx(SLOG_RAW_MSG,
 		    N_("ignoring lecture file %s: not a regular file"),
@@ -286,7 +289,10 @@ display_lecture(int status)
 	"    #2) Think before you type.\n"
 	"    #3) With great power comes great responsibility.\n\n");
     sudo_conv(1, &msg, &repl, NULL);
-    debug_return_bool(true);
+
+done:
+    closure->lectured = true;
+    debug_return;
 }
 
 /*

plugins/sudoers/check.h

@@ -1,7 +1,7 @@
 /*
  * SPDX-License-Identifier: ISC
  *
- * Copyright (c) 1993-1996,1998-2005, 2007-2014
+ * Copyright (c) 1993-1996, 1998-2005, 2007-2015, 2017-2018, 2021-2022
  *	Todd C. Miller <Todd.Miller@sudo.ws>
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -83,8 +83,9 @@ bool  timestamp_lock(void *vcookie, struct passwd *pw);
 bool  timestamp_update(void *vcookie, struct passwd *pw);
 int   timestamp_status(void *vcookie, struct passwd *pw);
 int   get_starttime(pid_t pid, struct timespec *starttime);
-bool  already_lectured(int status);
+bool  already_lectured(void);
 int   set_lectured(void);
+void display_lecture(struct sudo_conv_callback *callback);
 int   create_admin_success_flag(void);
 
 #endif /* SUDOERS_CHECK_H */

plugins/sudoers/timestamp.c

@@ -1,7 +1,7 @@
 /*
  * SPDX-License-Identifier: ISC
  *
- * Copyright (c) 2014-2021 Todd C. Miller <Todd.Miller@sudo.ws>
+ * Copyright (c) 2014-2022 Todd C. Miller <Todd.Miller@sudo.ws>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -1033,7 +1033,7 @@ done:
  * Returns true if the user has already been lectured.
  */
 bool
-already_lectured(int unused)
+already_lectured(void)
 {
     char status_file[PATH_MAX];
     struct stat sb;