- (djm) Much KNF on PAM code

- (djm) Revise auth-pam.c conversation function to be a little more readable. - (djm) Revise kbd-int PAM conversation function to fold all text messages to before first prompt. Fixes hangs if last pam_message did not require a reply. - (djm) Fix password changing when using PAM kbd-int authentication
2001-02-07 12:58:33 +11:00 · 2001-02-07 12:58:33 +11:00 · 63dc3e90e5
parent 582d3983d2
commit 63dc3e90e5
4 changed files with 170 additions and 166 deletions
--- a/6
+++ b/6
@ -1,6 +1,12 @@
 20010107
 - (bal) Save the whole path to AR in configure.  Some Solaris 2.7 installs
   seem lose track of it while in openbsd-compat/  (two confirmed reports)
+ - (djm) Much KNF on PAM code
+ - (djm) Revise auth-pam.c conversation function to be a little more readable.
+ - (djm) Revise kbd-int PAM conversation function to fold all text messages
+   to before first prompt. Fixes hangs if last pam_message did not require
+   a reply.
+ - (djm) Fix password changing when using PAM kbd-int authentication

 20010105
 - (bal) Disable groupaccess by setting NGROUPS_MAX to 0 for platforms
--- a/auth-pam.c
+++ b/auth-pam.c
@ -28,31 +28,29 @@
 #include "ssh.h"
 #include "xmalloc.h"
 #include "log.h"
+#include "auth-pam.h"
 #include "servconf.h"
 #include "canohost.h"
 #include "readpass.h"

-RCSID("$Id: auth-pam.c,v 1.24 2001/02/05 12:42:17 stevesk Exp $");
+RCSID("$Id: auth-pam.c,v 1.25 2001/02/07 01:58:34 djm Exp $");

 #define NEW_AUTHTOK_MSG \
 	"Warning: Your password has expired, please change it now"

-/* Callbacks */
-static int pamconv(int num_msg, const struct pam_message **msg,
+static int do_pam_conversation(int num_msg, const struct pam_message **msg,
 	struct pam_response **resp, void *appdata_ptr);
-void pam_cleanup_proc(void *context);
-void pam_msg_cat(const char *msg);

 /* module-local variables */
 static struct pam_conv conv = {
-	pamconv,
+	do_pam_conversation,
 	NULL
 };
+static char *pam_msg = NULL;
 static pam_handle_t *pamh = NULL;
 static const char *pampasswd = NULL;
-static char *pam_msg = NULL;

-/* states for pamconv() */
+/* states for do_pam_conversation() */
 enum { INITIAL_LOGIN, OTHER } pamstate = INITIAL_LOGIN;
 /* remember whether pam_acct_mgmt() returned PAM_NEWAUTHTOK_REQD */
 static int password_change_required = 0;
@ -80,14 +78,14 @@ int do_pam_authenticate(int flags)
 *
 * INITIAL_LOGIN mode simply feeds the password from the client into
 * PAM in response to PAM_PROMPT_ECHO_OFF, and collects output
- * messages with pam_msg_cat().  This is used during initial
+ * messages with into pam_msg.  This is used during initial
 * authentication to bypass the normal PAM password prompt.
 *
 * OTHER mode handles PAM_PROMPT_ECHO_OFF with read_passphrase(prompt, 1)
 * and outputs messages to stderr. This mode is used if pam_chauthtok()
 * is called to update expired passwords.
 */
-static int pamconv(int num_msg, const struct pam_message **msg,
+static int do_pam_conversation(int num_msg, const struct pam_message **msg,
 	struct pam_response **resp, void *appdata_ptr)
 {
 	struct pam_response *reply;
@ -100,40 +98,28 @@ static int pamconv(int num_msg, const struct pam_message **msg,
 		return PAM_CONV_ERR;

 	for (count = 0; count < num_msg; count++) {
+		if (pamstate == INITIAL_LOGIN) {
+			/*
+			 * We can't use stdio yet, queue messages for 
+			 * printing later
+			 */
 			switch(PAM_MSG_MEMBER(msg, count, msg_style)) {
 			case PAM_PROMPT_ECHO_ON:
-				if (pamstate == INITIAL_LOGIN) {
 				free(reply);
 				return PAM_CONV_ERR;
-				} else {
-					fputs(PAM_MSG_MEMBER(msg, count, msg), stderr);
-					fgets(buf, sizeof(buf), stdin);
-					reply[count].resp = xstrdup(buf);
-					reply[count].resp_retcode = PAM_SUCCESS;
-					break;
-				}
 			case PAM_PROMPT_ECHO_OFF:
-				if (pamstate == INITIAL_LOGIN) {
 				if (pampasswd == NULL) {
 					free(reply);
 					return PAM_CONV_ERR;
 				}
 				reply[count].resp = xstrdup(pampasswd);
-				} else {
-					reply[count].resp =
-						xstrdup(read_passphrase(PAM_MSG_MEMBER(msg, count, msg), 1));
-				}
 				reply[count].resp_retcode = PAM_SUCCESS;
 				break;
 			case PAM_ERROR_MSG:
 			case PAM_TEXT_INFO:
 				if ((*msg)[count].msg != NULL) {
-					if (pamstate == INITIAL_LOGIN)
-						pam_msg_cat(PAM_MSG_MEMBER(msg, count, msg));
-					else {
-						fputs(PAM_MSG_MEMBER(msg, count, msg), stderr);
-						fputs("\n", stderr);
-					}
+					message_cat(&pam_msg, 
+					    PAM_MSG_MEMBER(msg, count, msg));
 				}
 				reply[count].resp = xstrdup("");
 				reply[count].resp_retcode = PAM_SUCCESS;
@ -142,6 +128,36 @@ static int pamconv(int num_msg, const struct pam_message **msg,
 				free(reply);
 				return PAM_CONV_ERR;
 			}
+		} else {
+			/*
+			 * stdio is connected, so interact directly
+			 */
+			switch(PAM_MSG_MEMBER(msg, count, msg_style)) {
+			case PAM_PROMPT_ECHO_ON:
+				fputs(PAM_MSG_MEMBER(msg, count, msg), stderr);
+				fgets(buf, sizeof(buf), stdin);
+				reply[count].resp = xstrdup(buf);
+				reply[count].resp_retcode = PAM_SUCCESS;
+				break;
+			case PAM_PROMPT_ECHO_OFF:
+				reply[count].resp = xstrdup(
+				    read_passphrase(PAM_MSG_MEMBER(msg, count, 
+				    msg), 1));
+				reply[count].resp_retcode = PAM_SUCCESS;
+				break;
+			case PAM_ERROR_MSG:
+			case PAM_TEXT_INFO:
+				if ((*msg)[count].msg != NULL)
+					fprintf(stderr, "%s\n", 
+					    PAM_MSG_MEMBER(msg, count, msg));
+				reply[count].resp = xstrdup("");
+				reply[count].resp_retcode = PAM_SUCCESS;
+				break;
+			default:
+				free(reply);
+				return PAM_CONV_ERR;
+			}
+		}
 	}

 	*resp = reply;
@ -154,26 +170,22 @@ void pam_cleanup_proc(void *context)
 {
 	int pam_retval;

-	if (pamh != NULL)
-	{
+	if (pamh) {
 		pam_retval = pam_close_session(pamh, 0);
-		if (pam_retval != PAM_SUCCESS) {
+		if (pam_retval != PAM_SUCCESS)
 			log("Cannot close PAM session[%d]: %.200s",
 			    pam_retval, PAM_STRERROR(pamh, pam_retval));
-		}

 		pam_retval = pam_setcred(pamh, PAM_DELETE_CRED);
-		if (pam_retval != PAM_SUCCESS) {
+		if (pam_retval != PAM_SUCCESS)
 			debug("Cannot delete credentials[%d]: %.200s", 
 			    pam_retval, PAM_STRERROR(pamh, pam_retval));
-		}

 		pam_retval = pam_end(pamh, pam_retval);
-		if (pam_retval != PAM_SUCCESS) {
+		if (pam_retval != PAM_SUCCESS)
 			log("Cannot release PAM authentication[%d]: %.200s",
 			    pam_retval, PAM_STRERROR(pamh, pam_retval));
 	}
-	}
 }

 /* Attempt password authentation using PAM */
@ -197,12 +209,13 @@ int auth_pam_password(struct passwd *pw, const char *password)
 	pamstate = INITIAL_LOGIN;
 	pam_retval = do_pam_authenticate(0);
 	if (pam_retval == PAM_SUCCESS) {
-		debug("PAM Password authentication accepted for user \"%.100s\"",
-			pw->pw_name);
+		debug("PAM Password authentication accepted for "
+		    "user \"%.100s\"", pw->pw_name);
 		return 1;
 	} else {
-		debug("PAM Password authentication for \"%.100s\" failed[%d]: %s",
-			pw->pw_name, pam_retval, PAM_STRERROR(pamh, pam_retval));
+		debug("PAM Password authentication for \"%.100s\" "
+		    "failed[%d]: %s", pw->pw_name, pam_retval, 
+		    PAM_STRERROR(pamh, pam_retval));
 		return 0;
 	}
 }
@ -213,22 +226,21 @@ int do_pam_account(char *username, char *remote_user)
 	int pam_retval;
 	extern ServerOptions options;

+	pam_set_conv(&conv);
+
 	debug("PAM setting rhost to \"%.200s\"",
 	    get_canonical_hostname(options.reverse_mapping_check));
 	pam_retval = pam_set_item(pamh, PAM_RHOST,
 		get_canonical_hostname(options.reverse_mapping_check));
-	if (pam_retval != PAM_SUCCESS) {
-		fatal("PAM set rhost failed[%d]: %.200s",
-			pam_retval, PAM_STRERROR(pamh, pam_retval));
-	}
-
-	if (remote_user != NULL) {
+	if (pam_retval != PAM_SUCCESS)
+		fatal("PAM set rhost failed[%d]: %.200s", pam_retval,
+		    PAM_STRERROR(pamh, pam_retval));
+	if (remote_user) {
 		debug("PAM setting ruser to \"%.200s\"", remote_user);
 		pam_retval = pam_set_item(pamh, PAM_RUSER, remote_user);
-		if (pam_retval != PAM_SUCCESS) {
-			fatal("PAM set ruser failed[%d]: %.200s",
-				pam_retval, PAM_STRERROR(pamh, pam_retval));
-		}
+		if (pam_retval != PAM_SUCCESS)
+			fatal("PAM set ruser failed[%d]: %.200s", pam_retval, 
+			    PAM_STRERROR(pamh, pam_retval));
 	}

 	pam_retval = pam_acct_mgmt(pamh, 0);
@ -237,13 +249,14 @@ int do_pam_account(char *username, char *remote_user)
 			/* This is what we want */
 			break;
 		case PAM_NEW_AUTHTOK_REQD:
-			pam_msg_cat(NEW_AUTHTOK_MSG);
+			message_cat(&pam_msg, NEW_AUTHTOK_MSG);
 			/* flag that password change is necessary */
 			password_change_required = 1;
 			break;
 		default:
-			log("PAM rejected by account configuration[%d]: %.200s",
-				pam_retval, PAM_STRERROR(pamh, pam_retval));
+			log("PAM rejected by account configuration[%d]: "
+			    "%.200s", pam_retval, PAM_STRERROR(pamh, 
+			    pam_retval));
 			return(0);
 	}

@ -258,17 +271,15 @@ void do_pam_session(char *username, const char *ttyname)
 	if (ttyname != NULL) {
 		debug("PAM setting tty to \"%.200s\"", ttyname);
 		pam_retval = pam_set_item(pamh, PAM_TTY, ttyname);
-		if (pam_retval != PAM_SUCCESS) {
+		if (pam_retval != PAM_SUCCESS)
 			fatal("PAM set tty failed[%d]: %.200s",
 			    pam_retval, PAM_STRERROR(pamh, pam_retval));
 	}
-	}

 	pam_retval = pam_open_session(pamh, 0);
-	if (pam_retval != PAM_SUCCESS) {
+	if (pam_retval != PAM_SUCCESS)
 		fatal("PAM session setup failed[%d]: %.200s",
 		    pam_retval, PAM_STRERROR(pamh, pam_retval));
-	}
 }

 /* Set PAM credentials */
@ -279,14 +290,13 @@ void do_pam_setcred(void)
 	debug("PAM establishing creds");
 	pam_retval = pam_setcred(pamh, PAM_ESTABLISH_CRED);
 	if (pam_retval != PAM_SUCCESS) {
-		if(was_authenticated) {
+		if (was_authenticated)
 			fatal("PAM setcred failed[%d]: %.200s",
 			    pam_retval, PAM_STRERROR(pamh, pam_retval));
-		} else {
+		else
 			debug("PAM setcred failed[%d]: %.200s",
 			    pam_retval, PAM_STRERROR(pamh, pam_retval));
 	}
-	}
 }

 /* accessor function for file scope static variable */
@ -307,15 +317,13 @@ void do_pam_chauthtok(void)

 	if (password_change_required) {
 		pamstate = OTHER;
-		/*
-		 * XXX: should we really loop forever?
-		 */
+		/* XXX: should we really loop forever? */
 		do {
-			pam_retval = pam_chauthtok(pamh, PAM_CHANGE_EXPIRED_AUTHTOK);
-			if (pam_retval != PAM_SUCCESS) {
+			pam_retval = pam_chauthtok(pamh, 
+			    PAM_CHANGE_EXPIRED_AUTHTOK);
+			if (pam_retval != PAM_SUCCESS)
 				log("PAM pam_chauthtok failed[%d]: %.200s",
 				    pam_retval, PAM_STRERROR(pamh, pam_retval));
-			}
 		} while (pam_retval != PAM_SUCCESS);
 	}
 }
@ -336,11 +344,9 @@ void start_pam(const char *user)

 	pam_retval = pam_start(SSHD_PAM_SERVICE, user, &conv, &pamh);

-	if (pam_retval != PAM_SUCCESS) {
+	if (pam_retval != PAM_SUCCESS)
 		fatal("PAM initialisation failed[%d]: %.200s",
 		    pam_retval, PAM_STRERROR(pamh, pam_retval));
-	}
-
 #ifdef PAM_TTY_KLUDGE
 	/*
 	 * Some PAM modules (e.g. pam_time) require a TTY to operate,
@ -350,10 +356,9 @@ void start_pam(const char *user)
 	 * Kludge: Set a fake PAM_TTY
 	 */
 	pam_retval = pam_set_item(pamh, PAM_TTY, "ssh");
-	if (pam_retval != PAM_SUCCESS) {
+	if (pam_retval != PAM_SUCCESS)
 		fatal("PAM set tty failed[%d]: %.200s",
 		    pam_retval, PAM_STRERROR(pamh, pam_retval));
-	}
 #endif /* PAM_TTY_KLUDGE */

 	fatal_add_cleanup(&pam_cleanup_proc, NULL);
@ -377,26 +382,25 @@ void print_pam_messages(void)
 		fputs(pam_msg, stderr);
 }

-/* Append a message to the PAM message buffer */
-void pam_msg_cat(const char *msg)
+/* Append a message to buffer */
+void message_cat(char **p, const char *a)
 {
-	char *p;
-	size_t new_msg_len;
-	size_t pam_msg_len;
+	char *cp;
+	size_t new_len;

-	new_msg_len = strlen(msg);
+	new_len = strlen(a);

-	if (pam_msg) {
-		pam_msg_len = strlen(pam_msg);
-		pam_msg = xrealloc(pam_msg, new_msg_len + pam_msg_len + 2);
-		p = pam_msg + pam_msg_len;
-	} else {
-		pam_msg = p = xmalloc(new_msg_len + 2);
-	}
+	if (*p) {
+		size_t len = strlen(*p);

-	memcpy(p, msg, new_msg_len);
-	p[new_msg_len] = '\n';
-	p[new_msg_len + 1] = '\0';
+		*p = xrealloc(*p, new_len + len + 2);
+		cp = *p + len;
+	} else
+		*p = cp = xmalloc(new_len + 2);
+
+	memcpy(cp, a, new_len);
+	cp[new_len] = '\n';
+	cp[new_len + 1] = '\0';
 }

 #endif /* USE_PAM */
--- a/auth-pam.h
+++ b/auth-pam.h
@ -15,5 +15,6 @@ void print_pam_messages(void);
 int pam_password_change_required(void);
 void do_pam_chauthtok(void);
 void pam_set_conv(struct pam_conv *);
+void message_cat(char **p, const char *a);

 #endif /* USE_PAM */
--- a/auth2-pam.c
+++ b/auth2-pam.c
@ -1,5 +1,5 @@
 #include "includes.h"
-RCSID("$Id: auth2-pam.c,v 1.7 2001/01/30 23:50:49 djm Exp $");
+RCSID("$Id: auth2-pam.c,v 1.8 2001/02/07 01:58:33 djm Exp $");

 #ifdef USE_PAM
 #include <security/pam_appl.h>
@ -7,28 +7,28 @@ RCSID("$Id: auth2-pam.c,v 1.7 2001/01/30 23:50:49 djm Exp $");
 #include "ssh.h"
 #include "ssh2.h"
 #include "auth.h"
+#include "auth-pam.h"
 #include "packet.h"
 #include "xmalloc.h"
 #include "dispatch.h"
 #include "log.h"

+static int do_pam_conversation_kbd_int(int num_msg, 
+    const struct pam_message **msg, struct pam_response **resp, 
+    void *appdata_ptr);
+void input_userauth_info_response_pam(int type, int plen, void *ctxt);
+
 struct {
 	int finished, num_received, num_expected;
 	int *prompts;
 	struct pam_response *responses;
 } context_pam2 = {0, 0, 0, NULL};

-static int do_conversation2(int num_msg, const struct pam_message **msg,
-			    struct pam_response **resp, void *appdata_ptr);
-
-static struct pam_conv
-conv2 = {
-	do_conversation2,
+static struct pam_conv conv2 = {
+	do_pam_conversation_kbd_int,
 	NULL,
 };

-void input_userauth_info_response_pam(int type, int plen, void *ctxt);
-
 int
 auth2_pam(Authctxt *authctxt)
 {
@ -49,11 +49,11 @@ auth2_pam(Authctxt *authctxt)
 }

 static int
-do_conversation2(int num_msg, const struct pam_message **msg,
+do_pam_conversation_kbd_int(int num_msg, const struct pam_message **msg,
    struct pam_response **resp, void *appdata_ptr)
 {
-	int echo = 0, i = 0, j = 0, done = 0;
-	char *tmp = NULL, *text = NULL;
+	int i, j, done;
+	char *text;

 	context_pam2.finished = 0;
 	context_pam2.num_received = 0;
@ -62,53 +62,47 @@ do_conversation2(int num_msg, const struct pam_message **msg,
 	context_pam2.responses = xmalloc(sizeof(struct pam_response) * num_msg);
 	memset(context_pam2.responses, 0, sizeof(struct pam_response) * num_msg);

+	text = NULL;
+	for (i = 0, context_pam2.num_expected = 0; i < num_msg; i++) {
+		int style = PAM_MSG_MEMBER(msg, i, msg_style);
+		switch (style) {
+		case PAM_PROMPT_ECHO_ON:
+		case PAM_PROMPT_ECHO_OFF:
+			context_pam2.num_expected++;
+			break;
+		case PAM_TEXT_INFO:
+		case PAM_ERROR_MSG:
+		default:
+			/* Capture all these messages to be sent at once */
+			message_cat(&text, PAM_MSG_MEMBER(msg, i, msg));
+			break;
+		}
+	}
+
+	if (context_pam2.num_expected == 0)
+		return PAM_SUCCESS;
+
 	packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST);
 	packet_put_cstring("");	/* Name */
 	packet_put_cstring("");	/* Instructions */
 	packet_put_cstring("");	/* Language */
+	packet_put_int(context_pam2.num_expected);
+	
 	for (i = 0, j = 0; i < num_msg; i++) {
-		if((PAM_MSG_MEMBER(msg, i, msg_style) == PAM_PROMPT_ECHO_ON) ||
-		   (PAM_MSG_MEMBER(msg, i, msg_style) == PAM_PROMPT_ECHO_OFF) ||
-		   (i == num_msg - 1)) {
-			j++;
-		}
-	}
-	packet_put_int(j);				/* Number of prompts. */
-	context_pam2.num_expected = j;
-	for (i = 0, j = 0; i < num_msg; i++) {
-		switch(PAM_MSG_MEMBER(msg, i, msg_style)) {
-			case PAM_PROMPT_ECHO_ON:
-				echo = 1;
-				break;
-			case PAM_PROMPT_ECHO_OFF:
-				echo = 0;
-				break;
-			default:
-				echo = 0;
-				break;
-		}
-		if(text) {
-			tmp = xmalloc(strlen(text) + strlen(PAM_MSG_MEMBER(msg, i, msg)) + 2);
-			strcpy(tmp, text);
-			strcat(tmp, "\n");
-			strcat(tmp, PAM_MSG_MEMBER(msg, i, msg));
-			xfree(text);
-			text = tmp;
-			tmp = NULL;
-		} else {
-			text = xstrdup(PAM_MSG_MEMBER(msg, i, msg));
-		}
-		if((PAM_MSG_MEMBER(msg, i, msg_style) == PAM_PROMPT_ECHO_ON) ||
-		   (PAM_MSG_MEMBER(msg, i, msg_style) == PAM_PROMPT_ECHO_OFF) ||
-		   (i == num_msg - 1)) {
-			debug("sending prompt ssh-%d(pam-%d) = \"%s\"",
-			      j, i, text);
+		int style = PAM_MSG_MEMBER(msg, i, msg_style);
+		
+		/* Skip messages which don't need a reply */
+		if (style != PAM_PROMPT_ECHO_ON && style != PAM_PROMPT_ECHO_OFF)
+			continue;
+		
 		context_pam2.prompts[j++] = i;
+		if (text) {
+			message_cat(&text, PAM_MSG_MEMBER(msg, i, msg));
 			packet_put_cstring(text);
-			packet_put_char(echo);
-			xfree(text);
 			text = NULL;
-		}
+		} else
+			packet_put_cstring(PAM_MSG_MEMBER(msg, i, msg));
+		packet_put_char(style == PAM_PROMPT_ECHO_ON);
 	}
 	packet_send();
 	packet_write_wait();
@ -120,17 +114,15 @@ do_conversation2(int num_msg, const struct pam_message **msg,
 	while(context_pam2.finished == 0) {
 		done = 1;
 		dispatch_run(DISPATCH_BLOCK, &done, appdata_ptr);
-		if(context_pam2.finished == 0) {
+		if(context_pam2.finished == 0)
 			debug("extra packet during conversation");
 	}
-	}

 	if(context_pam2.num_received == context_pam2.num_expected) {
 		*resp = context_pam2.responses;
 		return PAM_SUCCESS;
-	} else {
+	} else
 		return PAM_CONV_ERR;
-	}
 }

 void
@ -151,6 +143,7 @@ input_userauth_info_response_pam(int type, int plen, void *ctxt)

 	for (i = 0; i < nresp; i++) {
 		int j = context_pam2.prompts[i];
+
 		resp = packet_get_string(&rlen);
 		context_pam2.responses[j].resp_retcode = PAM_SUCCESS;
 		context_pam2.responses[j].resp = xstrdup(resp);