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From 27d04a849fd9f9cfd4b35eb80d687817830183df Mon Sep 17 00:00:00 2001
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From: Tomas Mraz <tmraz@fedoraproject.org>
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Date: Wed, 7 Aug 2019 12:22:55 +0200
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Subject: [PATCH] pam_get_authtok_verify: Avoid duplicate password verification
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If password was already verified by previous modules in the stack
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it does not need to be verified by pam_get_authtok_verify either.
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* libpam/pam_get_authtok.c (pam_get_authtok_internal): Set the authtok_verified
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  appropriately.
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  (pam_get_authtok_verify): Do not prompt if authtok_verified is set and
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  set it when the password is verified.
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* libpam/pam_private.h: Add authtok_verified to the pam handle struct.
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* libpam/pam_start.c (pam_start): Initialize authtok_verified.
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---
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 libpam/pam_get_authtok.c | 10 ++++++++++
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 libpam/pam_private.h     |  1 +
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 libpam/pam_start.c       |  1 +
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 3 files changed, 12 insertions(+)
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diff --git a/libpam/pam_get_authtok.c b/libpam/pam_get_authtok.c
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index 800c6e5..99eb25f 100644
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--- a/libpam/pam_get_authtok.c
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+++ b/libpam/pam_get_authtok.c
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@@ -140,6 +140,8 @@ pam_get_authtok_internal (pam_handle_t *pamh, int item,
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     }
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   else if (chpass)
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     {
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+      pamh->authtok_verified = 0;
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+
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       retval = pam_prompt (pamh, PAM_PROMPT_ECHO_OFF, &resp[0],
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 			   PROMPT1, authtok_type,
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 			   strlen (authtok_type) > 0?" ":"");
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@@ -184,6 +186,9 @@ pam_get_authtok_internal (pam_handle_t *pamh, int item,
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   if (retval != PAM_SUCCESS)
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     return retval;
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+  if (chpass > 1)
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+    pamh->authtok_verified = 1;
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+
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   return pam_get_item(pamh, item, (const void **)authtok);
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 }
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@@ -214,6 +219,9 @@ pam_get_authtok_verify (pam_handle_t *pamh, const char **authtok,
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   if (authtok == NULL || pamh->choice != PAM_CHAUTHTOK)
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     return PAM_SYSTEM_ERR;
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+  if (pamh->authtok_verified)
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+    return pam_get_item (pamh, PAM_AUTHTOK, (const void **)authtok);
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+
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   if (prompt != NULL)
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     {
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       retval = pam_prompt (pamh, PAM_PROMPT_ECHO_OFF, &resp,
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@@ -252,5 +260,7 @@ pam_get_authtok_verify (pam_handle_t *pamh, const char **authtok,
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   if (retval != PAM_SUCCESS)
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     return retval;
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+  pamh->authtok_verified = 1;
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+
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   return pam_get_item(pamh, PAM_AUTHTOK, (const void **)authtok);
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 }
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diff --git a/libpam/pam_private.h b/libpam/pam_private.h
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index 7ff9f75..58a26f5 100644
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--- a/libpam/pam_private.h
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+++ b/libpam/pam_private.h
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@@ -172,6 +172,7 @@ struct pam_handle {
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 #ifdef HAVE_LIBAUDIT
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     int audit_state;             /* keep track of reported audit messages */
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 #endif
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+    int authtok_verified;
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 };
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 /* Values for select arg to _pam_dispatch() */
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diff --git a/libpam/pam_start.c b/libpam/pam_start.c
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index 328416d..e27c64b 100644
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--- a/libpam/pam_start.c
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+++ b/libpam/pam_start.c
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@@ -94,6 +94,7 @@ int pam_start (
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 #endif
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     (*pamh)->xdisplay = NULL;
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     (*pamh)->authtok_type = NULL;
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+    (*pamh)->authtok_verified = 0;
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     memset (&((*pamh)->xauth), 0, sizeof ((*pamh)->xauth));
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     if (((*pamh)->pam_conversation = (struct pam_conv *)
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-- 
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2.20.1
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