X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/09564242cbaea8c8ca030de32a0c55118b63bc27..68ece370ced3c762375a98bb1411996e1183f125:/auth-pam.c

diff --git a/auth-pam.c b/auth-pam.c
index 2a6d728e..da624e38 100644
--- a/auth-pam.c
+++ b/auth-pam.c
@@ -9,11 +9,6 @@
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- *    must display the following acknowledgement:
- *      This product includes software developed by Markus Friedl.
- * 4. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
@@ -30,64 +25,147 @@
 #include "includes.h"
 
 #ifdef USE_PAM
-#include "ssh.h"
 #include "xmalloc.h"
+#include "log.h"
+#include "auth.h"
+#include "auth-options.h"
+#include "auth-pam.h"
 #include "servconf.h"
+#include "canohost.h"
+#include "readpass.h"
+
+extern char *__progname;
+
+extern int use_privsep;
 
 RCSID("$Id$");
 
 #define NEW_AUTHTOK_MSG \
-	"Warning: You password has expired, please change it now"
+	"Warning: Your password has expired, please change it now."
+#define NEW_AUTHTOK_MSG_PRIVSEP \
+	"Your password has expired, the session cannot proceed."
 
-/* Callbacks */
-static int pamconv(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);
+static int do_pam_conversation(int num_msg, const struct pam_message **msg,
+	struct pam_response **resp, void *appdata_ptr);
 
 /* module-local variables */
 static struct pam_conv conv = {
-	pamconv,
+	(int (*)())do_pam_conversation,
 	NULL
 };
-static struct pam_handle_t *pamh = NULL;
-static const char *pampasswd = NULL;
-static char *pam_msg = NULL;
+static char *__pam_msg = NULL;
+static pam_handle_t *__pamh = NULL;
+static const char *__pampasswd = NULL;
+
+/* states for do_pam_conversation() */
+enum { INITIAL_LOGIN, OTHER } pamstate = INITIAL_LOGIN;
+/* remember whether pam_acct_mgmt() returned PAM_NEW_AUTHTOK_REQD */
+static int password_change_required = 0;
+/* remember whether the last pam_authenticate() succeeded or not */
+static int was_authenticated = 0;
+
+/* Remember what has been initialised */
+static int session_opened = 0;
+static int creds_set = 0;
+
+/* accessor which allows us to switch conversation structs according to
+ * the authentication method being used */
+void do_pam_set_conv(struct pam_conv *conv)
+{
+	pam_set_item(__pamh, PAM_CONV, conv);
+}
+
+/* start an authentication run */
+int do_pam_authenticate(int flags)
+{
+	int retval = pam_authenticate(__pamh, flags);
+	was_authenticated = (retval == PAM_SUCCESS);
+	return retval;
+}
 
-/* PAM conversation function. This is really a kludge to get the password */
-/* into PAM and to pick up any messages generated by PAM into pamconv_msg */
-static int pamconv(int num_msg, const struct pam_message **msg,
+/*
+ * PAM conversation function.
+ * There are two states this can run in.
+ *
+ * INITIAL_LOGIN mode simply feeds the password from the client into
+ * PAM in response to PAM_PROMPT_ECHO_OFF, and collects output
+ * 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()
+ * and outputs messages to stderr. This mode is used if pam_chauthtok()
+ * is called to update expired passwords.
+ */
+static int do_pam_conversation(int num_msg, const struct pam_message **msg,
 	struct pam_response **resp, void *appdata_ptr)
 {
 	struct pam_response *reply;
 	int count;
+	char buf[1024];
 
 	/* PAM will free this later */
-	reply = malloc(num_msg * sizeof(*reply));
-	if (reply == NULL)
-		return PAM_CONV_ERR; 
-
-	for(count = 0; count < num_msg; count++) {
-		switch (msg[count]->msg_style) {
+	reply = xmalloc(num_msg * sizeof(*reply));
+
+	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:
+				xfree(reply);
+				return PAM_CONV_ERR;
 			case PAM_PROMPT_ECHO_OFF:
-				if (pampasswd == NULL) {
-					free(reply);
+				if (__pampasswd == NULL) {
+					xfree(reply);
 					return PAM_CONV_ERR;
 				}
+				reply[count].resp = xstrdup(__pampasswd);
 				reply[count].resp_retcode = PAM_SUCCESS;
-				reply[count].resp = xstrdup(pampasswd);
 				break;
+			case PAM_ERROR_MSG:
 			case PAM_TEXT_INFO:
+				if (PAM_MSG_MEMBER(msg, count, msg) != NULL) {
+					message_cat(&__pam_msg, 
+					    PAM_MSG_MEMBER(msg, count, msg));
+				}
+				reply[count].resp = xstrdup("");
+				reply[count].resp_retcode = PAM_SUCCESS;
+				break;
+			default:
+				xfree(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 = 
+				    read_passphrase(PAM_MSG_MEMBER(msg, count,
+					msg), RP_ALLOW_STDIN);
+				reply[count].resp_retcode = PAM_SUCCESS;
+				break;
+			case PAM_ERROR_MSG:
+			case PAM_TEXT_INFO:
+				if (PAM_MSG_MEMBER(msg, count, msg) != NULL)
+					fprintf(stderr, "%s\n", 
+					    PAM_MSG_MEMBER(msg, count, msg));
 				reply[count].resp = xstrdup("");
-
-				if (msg[count]->msg != NULL)
-					pam_msg_cat(msg[count]->msg);
-
+				reply[count].resp_retcode = PAM_SUCCESS;
 				break;
 			default:
-				free(reply);
+				xfree(reply);
 				return PAM_CONV_ERR;
+			}
 		}
 	}
 
@@ -97,56 +175,54 @@ static int pamconv(int num_msg, const struct pam_message **msg,
 }
 
 /* Called at exit to cleanly shutdown PAM */
-void pam_cleanup_proc(void *context)
+void do_pam_cleanup_proc(void *context)
 {
-	int pam_retval;
+	int pam_retval = PAM_SUCCESS;
 
-	if (pamh != NULL)
-	{
-		pam_retval = pam_close_session((pam_handle_t *)pamh, 0);
-		if (pam_retval != PAM_SUCCESS) {
-			log("Cannot close PAM session: %.200s", 
-				PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
-		}
+	if (__pamh && session_opened) {
+		pam_retval = pam_close_session(__pamh, 0);
+		if (pam_retval != PAM_SUCCESS)
+			logit("Cannot close PAM session[%d]: %.200s",
+			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
+	}
 
-		pam_retval = pam_setcred((pam_handle_t *)pamh, PAM_DELETE_CRED);
-		if (pam_retval != PAM_SUCCESS) {
-			log("Cannot delete credentials: %.200s", 
-				PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
-		}
+	if (__pamh && creds_set) {
+		pam_retval = pam_setcred(__pamh, PAM_DELETE_CRED);
+		if (pam_retval != PAM_SUCCESS)
+			debug("Cannot delete credentials[%d]: %.200s", 
+			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
+	}
 
-		pam_retval = pam_end((pam_handle_t *)pamh, pam_retval);
-		if (pam_retval != PAM_SUCCESS) {
-			log("Cannot release PAM authentication: %.200s", 
-				PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
-		}
+	if (__pamh) {
+		pam_retval = pam_end(__pamh, pam_retval);
+		if (pam_retval != PAM_SUCCESS)
+			logit("Cannot release PAM authentication[%d]: %.200s",
+			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
 	}
 }
 
-/* Attempt password authentation using PAM */
-int auth_pam_password(struct passwd *pw, const char *password)
+/* Attempt password authentication using PAM */
+int auth_pam_password(Authctxt *authctxt, const char *password)
 {
 	extern ServerOptions options;
 	int pam_retval;
+	struct passwd *pw = authctxt->pw;
 
-	/* deny if no user. */
-	if (pw == NULL)
-		return 0;
-	if (pw->pw_uid == 0 && options.permit_root_login == 2)
-		return 0;
-	if (*password == '\0' && options.permit_empty_passwd == 0)
-		return 0;
+	do_pam_set_conv(&conv);
 
-	pampasswd = password;
-	
-	pam_retval = pam_authenticate((pam_handle_t *)pamh, 0);
-	if (pam_retval == PAM_SUCCESS) {
-		debug("PAM Password authentication accepted for user \"%.100s\"", 
-			pw->pw_name);
+	__pampasswd = password;
+
+	pamstate = INITIAL_LOGIN;
+	pam_retval = do_pam_authenticate(
+	    options.permit_empty_passwd == 0 ? PAM_DISALLOW_NULL_AUTHTOK : 0);
+	if (pam_retval == PAM_SUCCESS && pw) {
+		debug("PAM password authentication accepted for "
+		    "%.100s", pw->pw_name);
 		return 1;
 	} else {
-		debug("PAM Password authentication for \"%.100s\" failed: %s", 
-			pw->pw_name, PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
+		debug("PAM password authentication failed for "
+		    "%.100s: %s", pw ? pw->pw_name : "an illegal user",
+		    PAM_STRERROR(__pamh, pam_retval));
 		return 0;
 	}
 }
@@ -155,38 +231,42 @@ int auth_pam_password(struct passwd *pw, const char *password)
 int do_pam_account(char *username, char *remote_user)
 {
 	int pam_retval;
-	
-	debug("PAM setting rhost to \"%.200s\"", get_canonical_hostname());
-	pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RHOST, 
-		get_canonical_hostname());
-	if (pam_retval != PAM_SUCCESS) {
-		fatal("PAM set rhost failed: %.200s", 
-			PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
-	}
 
-	if (remote_user != NULL) {
+	do_pam_set_conv(&conv);
+
+	if (remote_user) {
 		debug("PAM setting ruser to \"%.200s\"", remote_user);
-		pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RUSER, remote_user);
-		if (pam_retval != PAM_SUCCESS) {
-			fatal("PAM set ruser failed: %.200s", 
-				PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
-		}
+		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));
 	}
 
-	pam_retval = pam_acct_mgmt((pam_handle_t *)pamh, 0);
+	pam_retval = pam_acct_mgmt(__pamh, 0);
+	debug2("pam_acct_mgmt() = %d", pam_retval);
 	switch (pam_retval) {
 		case PAM_SUCCESS:
 			/* This is what we want */
 			break;
+#if 0
 		case PAM_NEW_AUTHTOK_REQD:
-			pam_msg_cat(NEW_AUTHTOK_MSG);
+			message_cat(&__pam_msg, use_privsep ?
+			    NEW_AUTHTOK_MSG_PRIVSEP : NEW_AUTHTOK_MSG);
+			/* flag that password change is necessary */
+			password_change_required = 1;
+			/* disallow other functionality for now */
+			no_port_forwarding_flag |= 2;
+			no_agent_forwarding_flag |= 2;
+			no_x11_forwarding_flag |= 2;
 			break;
+#endif
 		default:
-			log("PAM rejected by account configuration: %.200s", 
-				PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
+			logit("PAM rejected by account configuration[%d]: "
+			    "%.200s", pam_retval, PAM_STRERROR(__pamh, 
+			    pam_retval));
 			return(0);
 	}
-	
+
 	return(1);
 }
 
@@ -195,98 +275,181 @@ void do_pam_session(char *username, const char *ttyname)
 {
 	int pam_retval;
 
+	do_pam_set_conv(&conv);
+
 	if (ttyname != NULL) {
 		debug("PAM setting tty to \"%.200s\"", ttyname);
-		pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_TTY, ttyname);
-		if (pam_retval != PAM_SUCCESS) {
-			fatal("PAM set tty failed: %.200s", 
-				PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
-		}
+		pam_retval = pam_set_item(__pamh, PAM_TTY, ttyname);
+		if (pam_retval != PAM_SUCCESS)
+			fatal("PAM set tty failed[%d]: %.200s",
+			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
 	}
 
-	pam_retval = pam_open_session((pam_handle_t *)pamh, 0);
-	if (pam_retval != PAM_SUCCESS) {
-		fatal("PAM session setup failed: %.200s", 
-			PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
-	}
+	pam_retval = pam_open_session(__pamh, 0);
+	if (pam_retval != PAM_SUCCESS)
+		fatal("PAM session setup failed[%d]: %.200s",
+		    pam_retval, PAM_STRERROR(__pamh, pam_retval));
+
+	session_opened = 1;
 }
 
-/* Set PAM credentials */ 
-void do_pam_setcred()
+/* Set PAM credentials */
+void do_pam_setcred(int init)
 {
 	int pam_retval;
- 
+
+	if (__pamh == NULL)
+		return;
+
+	do_pam_set_conv(&conv);
+
 	debug("PAM establishing creds");
-	pam_retval = pam_setcred((pam_handle_t *)pamh, PAM_ESTABLISH_CRED);
+	pam_retval = pam_setcred(__pamh, 
+	    init ? PAM_ESTABLISH_CRED : PAM_REINITIALIZE_CRED);
 	if (pam_retval != PAM_SUCCESS) {
-		fatal("PAM setcred failed: %.200s", 
-			PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
+		if (was_authenticated)
+			fatal("PAM setcred failed[%d]: %.200s",
+			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
+		else
+			debug("PAM setcred failed[%d]: %.200s",
+			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
+	} else
+		creds_set = 1;
+}
+
+/* accessor function for file scope static variable */
+int is_pam_password_change_required(void)
+{
+	return password_change_required;
+}
+
+/*
+ * Have user change authentication token if pam_acct_mgmt() indicated
+ * it was expired.  This needs to be called after an interactive
+ * session is established and the user's pty is connected to
+ * stdin/stdout/stderr.
+ */
+void do_pam_chauthtok(void)
+{
+	int pam_retval;
+
+	do_pam_set_conv(&conv);
+
+	if (password_change_required) {
+		if (use_privsep)
+			fatal("Password changing is currently unsupported"
+			    " with privilege separation");
+		pamstate = OTHER;
+		pam_retval = pam_chauthtok(__pamh, PAM_CHANGE_EXPIRED_AUTHTOK);
+		if (pam_retval != PAM_SUCCESS)
+			fatal("PAM pam_chauthtok failed[%d]: %.200s",
+			    pam_retval, PAM_STRERROR(__pamh, pam_retval));
+#if 0
+		/* XXX: This would need to be done in the parent process,
+		 * but there's currently no way to pass such request. */
+		no_port_forwarding_flag &= ~2;
+		no_agent_forwarding_flag &= ~2;
+		no_x11_forwarding_flag &= ~2;
+		if (!no_port_forwarding_flag && options.allow_tcp_forwarding)
+			channel_permit_all_opens();
+#endif
 	}
 }
 
 /* Cleanly shutdown PAM */
 void finish_pam(void)
 {
-	pam_cleanup_proc(NULL);
-	fatal_remove_cleanup(&pam_cleanup_proc, NULL);
+	do_pam_cleanup_proc(NULL);
+	fatal_remove_cleanup(&do_pam_cleanup_proc, NULL);
 }
 
 /* Start PAM authentication for specified account */
-void start_pam(struct passwd *pw)
+void start_pam(const char *user)
 {
 	int pam_retval;
-
-	debug("Starting up PAM with username \"%.200s\"", pw->pw_name);
-
-	pam_retval = pam_start(SSHD_PAM_SERVICE, pw->pw_name, &conv, 
-		(pam_handle_t**)&pamh);
-
-	if (pam_retval != PAM_SUCCESS) {
-		fatal("PAM initialisation failed: %.200s", 
-			PAM_STRERROR((pam_handle_t *)pamh, pam_retval));
-	}
-	
-	fatal_add_cleanup(&pam_cleanup_proc, NULL);
+	extern ServerOptions options;
+	extern u_int utmp_len;
+	const char *rhost;
+
+	debug("Starting up PAM with username \"%.200s\"", user);
+
+	pam_retval = pam_start(SSHD_PAM_SERVICE, user, &conv, &__pamh);
+
+	if (pam_retval != PAM_SUCCESS)
+		fatal("PAM initialisation failed[%d]: %.200s",
+		    pam_retval, PAM_STRERROR(__pamh, pam_retval));
+
+	rhost = get_remote_name_or_ip(utmp_len, options.verify_reverse_mapping);
+	debug("PAM setting rhost to \"%.200s\"", rhost);
+
+	pam_retval = pam_set_item(__pamh, PAM_RHOST, rhost);
+	if (pam_retval != PAM_SUCCESS)
+		fatal("PAM set rhost 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,
+	 * and will fail in various stupid ways if they don't get one.
+	 * sshd doesn't set the tty until too late in the auth process and may
+	 * not even need one (for tty-less connections)
+	 * Kludge: Set a fake PAM_TTY
+	 */
+	pam_retval = pam_set_item(__pamh, PAM_TTY, "NODEVssh");
+	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(&do_pam_cleanup_proc, NULL);
 }
 
-/* Return list of PAM enviornment strings */
+/* Return list of PAM environment strings */
 char **fetch_pam_environment(void)
 {
 #ifdef HAVE_PAM_GETENVLIST
-	return(pam_getenvlist((pam_handle_t *)pamh));
+	return(pam_getenvlist(__pamh));
 #else /* HAVE_PAM_GETENVLIST */
 	return(NULL);
 #endif /* HAVE_PAM_GETENVLIST */
 }
 
+void free_pam_environment(char **env)
+{
+	int i;
+
+	if (env != NULL) {
+		for (i = 0; env[i] != NULL; i++)
+			xfree(env[i]);
+	}
+}
+
 /* Print any messages that have been generated during authentication */
 /* or account checking to stderr */
 void print_pam_messages(void)
 {
-	if (pam_msg != NULL)
-		fprintf(stderr, pam_msg);
+	if (__pam_msg != NULL)
+		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;
-	
-	new_msg_len = strlen(msg);
-	
-	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);
-	}
+	char *cp;
+	size_t new_len;
+
+	new_len = strlen(a);
+
+	if (*p) {
+		size_t len = strlen(*p);
+
+		*p = xrealloc(*p, new_len + len + 2);
+		cp = *p + len;
+	} else
+		*p = cp = xmalloc(new_len + 2);
 
-	memcpy(p, msg, new_msg_len);
-	p[new_msg_len] = '\n';
-	p[new_msg_len + 1] = '\0';
+	memcpy(cp, a, new_len);
+	cp[new_len] = '\n';
+	cp[new_len + 1] = '\0';
 }
 
 #endif /* USE_PAM */