Relevant BUGIDs: 112540

Purpose of commit: minor security bugfix

Commit summary:
---------------
Fixes for the password helper binaries.
Before, there was no check that the password entered was actually that
of the intended user being authenticated. Instead, the password was
checked for the requesting user. While this disstinction sounds like a
security hole, its actually not been a problem in practice. The helper
binaries have only been used in the case that the application is not
setuid-0 and as such even if an improper authentication succeeded, the
application could not change its uid from that of the requesting user.

1 files changed, 20 insertions, 4 deletions

diff --git a/modules/pam_pwdb/pwdb_chkpwd.c b/modules/pam_pwdb/pwdb_chkpwd.c
index fdd3cfa3..36cf0984 100644
--- a/modules/pam_pwdb/pwdb_chkpwd.c
+++ b/modules/pam_pwdb/pwdb_chkpwd.c
@@ -83,12 +83,12 @@ static int _unix_verify_passwd(const char *salt, const char *p)
     return retval;
 }
 
-int main(void)
+int main(int argc, char **argv)
 {
     const struct pwdb *pw=NULL;
     const struct pwdb_entry *pwe=NULL;
     char pass[MAXPASS+1];
-    int npass;
+    int npass, force_failure=0;
     int retval=UNIX_FAILED;
 
     /*
@@ -120,14 +120,26 @@ int main(void)
 	retval = UNIX_FAILED;
     }
     if (retval != UNIX_FAILED) {
-	retval = pwdb_locate("user", PWDB_DEFAULT, PWDB_NAME_UNKNOWN
-			     , getuid(), &pw);
+	retval = pwdb_locate("user", PWDB_DEFAULT, PWDB_NAME_UNKNOWN,
+			     getuid(), &pw);
     }
     if (retval != PWDB_SUCCESS) {
 	_log_err(LOG_ALERT, "could not identify user");
 	while (pwdb_end() != PWDB_SUCCESS);
 	exit(UNIX_FAILED);
     }
+    if (argc == 2) {
+	if (pwdb_get_entry(pw, "user", &pwe) == PWDB_SUCCESS) {
+	    if (pwe == NULL) {
+		force_failure = 1;
+	    } else {
+		if (strcmp((const char *) pwe->value, argv[1])) {
+		    force_failure = 1;
+		}
+		pwdb_entry_delete(&pwe);
+	    }
+	}
+    }
 
     /* read the password from stdin (a pipe from the pam_pwdb module) */
 
@@ -158,6 +170,10 @@ int main(void)
     memset(pass, '\0', MAXPASS);        /* clear memory of the password */
     while (pwdb_end() != PWDB_SUCCESS);
 
+    if ((retval != UNIX_FAILED) && force_failure) {
+	retval = UNIX_FAILED;
+    }
+    
     /* return pass or fail */
 
     exit(retval);