]> andersk Git - openssh.git/blobdiff - auth-pam.c
- (dtucker) [auth-pam.c] Bug #705: Make arguments match PAM specs, fixes
[openssh.git] / auth-pam.c
index 6a78a287b34a4ee45194aab852a993eb82fd52ab..95930a93347fb39ddbd913c244d54a04853ab6d5 100644 (file)
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+/*
+ * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org>
+ * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
 
 /* Based on $FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */
 #include "includes.h"
@@ -169,6 +185,7 @@ static int sshpam_cred_established = 0;
 static int sshpam_account_status = -1;
 static char **sshpam_env = NULL;
 static Authctxt *sshpam_authctxt = NULL;
+static const char *sshpam_password = NULL;
 
 /* Some PAM implementations don't implement this */
 #ifndef HAVE_PAM_GETENVLIST
@@ -185,7 +202,7 @@ pam_getenvlist(pam_handle_t *pamh)
 #endif
 
 void
-pam_password_change_required(int reqd)
+sshpam_password_change_required(int reqd)
 {
        debug3("%s %d", __func__, reqd);
        if (sshpam_authctxt == NULL)
@@ -215,7 +232,7 @@ import_environments(Buffer *b)
 #ifndef USE_POSIX_THREADS
        /* Import variables set by do_pam_account */
        sshpam_account_status = buffer_get_int(b);
-       pam_password_change_required(buffer_get_int(b));
+       sshpam_password_change_required(buffer_get_int(b));
 
        /* Import environment from subprocess */
        num_env = buffer_get_int(b);
@@ -247,7 +264,7 @@ import_environments(Buffer *b)
  * Conversation function for authentication thread.
  */
 static int
-sshpam_thread_conv(int n, const struct pam_message **msg,
+sshpam_thread_conv(int n, struct pam_message **msg,
     struct pam_response **resp, void *data)
 {
        Buffer buffer;
@@ -258,6 +275,10 @@ sshpam_thread_conv(int n, const struct pam_message **msg,
        debug3("PAM: %s entering, %d messages", __func__, n);
        *resp = NULL;
 
+       if (data == NULL) {
+               error("PAM: conversation function passed a null context");
+               return (PAM_CONV_ERR);
+       }
        ctxt = data;
        if (n <= 0 || n > PAM_MAX_NUM_MSG)
                return (PAM_CONV_ERR);
@@ -341,7 +362,7 @@ sshpam_thread(void *ctxtp)
        u_int i;
        const char *pam_user;
 
-       pam_get_item(sshpam_handle, PAM_USER, (const void **)&pam_user);
+       pam_get_item(sshpam_handle, PAM_USER, (void **)&pam_user);
        setproctitle("%s [pam]", pam_user);
        environ[0] = NULL;
 #endif
@@ -369,7 +390,7 @@ sshpam_thread(void *ctxtp)
                            PAM_CHANGE_EXPIRED_AUTHTOK);
                        if (sshpam_err != PAM_SUCCESS)
                                goto auth_fail;
-                       pam_password_change_required(0);
+                       sshpam_password_change_required(0);
                }
        }
 
@@ -429,7 +450,7 @@ sshpam_thread_cleanup(void)
 }
 
 static int
-sshpam_null_conv(int n, const struct pam_message **msg,
+sshpam_null_conv(int n, struct pam_message **msg,
     struct pam_response **resp, void *data)
 {
        debug3("PAM: %s entering, %d messages", __func__, n);
@@ -467,7 +488,7 @@ sshpam_init(Authctxt *authctxt)
        if (sshpam_handle != NULL) {
                /* We already have a PAM context; check if the user matches */
                sshpam_err = pam_get_item(sshpam_handle,
-                   PAM_USER, (const void **)&pam_user);
+                   PAM_USER, (void **)&pam_user);
                if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
                        return (0);
                pam_end(sshpam_handle, sshpam_err);
@@ -719,7 +740,7 @@ do_pam_account(void)
        }
 
        if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
-               pam_password_change_required(1);
+               sshpam_password_change_required(1);
 
        sshpam_account_status = 1;
        return (sshpam_account_status);
@@ -765,7 +786,7 @@ do_pam_setcred(int init)
 }
 
 static int
-pam_tty_conv(int n, const struct pam_message **msg,
+sshpam_tty_conv(int n, struct pam_message **msg,
     struct pam_response **resp, void *data)
 {
        char input[PAM_MAX_MSG_SIZE];
@@ -818,7 +839,7 @@ pam_tty_conv(int n, const struct pam_message **msg,
        return (PAM_CONV_ERR);
 }
 
-static struct pam_conv tty_conv = { pam_tty_conv, NULL };
+static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };
 
 /*
  * XXX this should be done in the authentication phase, but ssh1 doesn't
@@ -842,7 +863,7 @@ do_pam_chauthtok(void)
 }
 
 static int
-pam_store_conv(int n, const struct pam_message **msg,
+sshpam_store_conv(int n, struct pam_message **msg,
     struct pam_response **resp, void *data)
 {
        struct pam_response *reply;
@@ -884,7 +905,7 @@ pam_store_conv(int n, const struct pam_message **msg,
        return (PAM_CONV_ERR);
 }
 
-static struct pam_conv store_conv = { pam_store_conv, NULL };
+static struct pam_conv store_conv = { sshpam_store_conv, NULL };
 
 void
 do_pam_session(void)
@@ -951,4 +972,110 @@ free_pam_environment(char **env)
        xfree(env);
 }
 
+/*
+ * "Blind" conversation function for password authentication.  Assumes that
+ * echo-off prompts are for the password and stores messages for later
+ * display.
+ */
+static int
+sshpam_passwd_conv(int n, struct pam_message **msg,
+    struct pam_response **resp, void *data)
+{
+       struct pam_response *reply;
+       int i;
+       size_t len;
+
+       debug3("PAM: %s called with %d messages", __func__, n);
+
+       *resp = NULL;
+
+       if (n <= 0 || n > PAM_MAX_NUM_MSG)
+               return (PAM_CONV_ERR);
+
+       if ((reply = malloc(n * sizeof(*reply))) == NULL)
+               return (PAM_CONV_ERR);
+       memset(reply, 0, n * sizeof(*reply));
+
+       for (i = 0; i < n; ++i) {
+               switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
+               case PAM_PROMPT_ECHO_OFF:
+                       if (sshpam_password == NULL)
+                               goto fail;
+                       reply[i].resp = xstrdup(sshpam_password);
+                       reply[i].resp_retcode = PAM_SUCCESS;
+                       break;
+               case PAM_ERROR_MSG:
+               case PAM_TEXT_INFO:
+                       len = strlen(PAM_MSG_MEMBER(msg, i, msg));
+                       if (len > 0) {
+                               buffer_append(&loginmsg,
+                                   PAM_MSG_MEMBER(msg, i, msg), len);
+                               buffer_append(&loginmsg, "\n", 1);
+                       }
+                       reply[i].resp = xstrdup("");
+                       reply[i].resp_retcode = PAM_SUCCESS;
+                       break;
+               default:
+                       goto fail;
+               }
+       }
+       *resp = reply;
+       return (PAM_SUCCESS);
+
+ fail: 
+       for(i = 0; i < n; i++) {
+               if (reply[i].resp != NULL)
+                       xfree(reply[i].resp);
+       }
+       xfree(reply);
+       return (PAM_CONV_ERR);
+}
+
+static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };
+
+/*
+ * Attempt password authentication via PAM
+ */
+int
+sshpam_auth_passwd(Authctxt *authctxt, const char *password)
+{
+       int flags = (options.permit_empty_passwd == 0 ?
+           PAM_DISALLOW_NULL_AUTHTOK : 0);
+       static char badpw[] = "\b\n\r\177INCORRECT";
+
+       if (!options.use_pam || sshpam_handle == NULL)
+               fatal("PAM: %s called when PAM disabled or failed to "
+                   "initialise.", __func__);
+
+       sshpam_password = password;
+       sshpam_authctxt = authctxt;
+
+       /*
+        * If the user logging in is invalid, or is root but is not permitted
+        * by PermitRootLogin, use an invalid password to prevent leaking
+        * information via timing (eg if the PAM config has a delay on fail).
+        */
+       if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
+            options.permit_root_login != PERMIT_YES))
+               sshpam_password = badpw;
+
+       sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
+           (const void *)&passwd_conv);
+       if (sshpam_err != PAM_SUCCESS)
+               fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
+                   pam_strerror(sshpam_handle, sshpam_err));
+
+       sshpam_err = pam_authenticate(sshpam_handle, flags);
+       sshpam_password = NULL;
+       if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
+               debug("PAM: password authentication accepted for %.100s",
+                   authctxt->user);
+               return 1;
+       } else {
+               debug("PAM: password authentication failed for %.100s: %s",
+                   authctxt->valid ? authctxt->user : "an illegal user",
+                   pam_strerror(sshpam_handle, sshpam_err));
+               return 0;
+       }
+}
 #endif /* USE_PAM */
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