Allow arbitrary-length PAM messages

The PAM standard allows for messages of any length to be returned
to the client. We were discarding all messages of length greater
than 255. This patch dynamically allocates the message buffers so
we can pass the complete message.

This resolves https://fedorahosted.org/sssd/ticket/432

1 files changed, 20 insertions, 3 deletions

diff --git a/src/sss_client/pam_sss.c b/src/sss_client/pam_sss.c
index 07ed4e721..6059dfaa1 100644
--- a/src/sss_client/pam_sss.c
+++ b/src/sss_client/pam_sss.c
@@ -588,7 +588,8 @@ static int user_info_chpass_error(pam_handle_t *pamh, size_t buflen,
 {
     int ret;
     uint32_t msg_len;
-    char user_msg[256];
+    char *user_msg;
+    size_t bufsize = 0;
 
     if (buflen < 2* sizeof(uint32_t)) {
         D(("User info response data is too short"));
@@ -602,19 +603,35 @@ static int user_info_chpass_error(pam_handle_t *pamh, size_t buflen,
         return PAM_BUF_ERR;
     }
 
-    ret = snprintf(user_msg, sizeof(user_msg), "%s%s%.*s",
+    bufsize = strlen(_("Password change failed. ")) + 1;
+
+    if (msg_len > 0) {
+        bufsize += strlen(_("Server message: ")) + msg_len;
+    }
+
+    user_msg = (char *)malloc(sizeof(char) * bufsize);
+    if (!user_msg) {
+       D(("Out of memory."));
+       return PAM_SYSTEM_ERR;
+    }
+
+    ret = snprintf(user_msg, bufsize, "%s%s%.*s",
                    _("Password change failed. "),
                    msg_len > 0 ? _("Server message: ") : "",
                    msg_len,
                    msg_len > 0 ? (char *)(buf + 2 * sizeof(uint32_t)) : "" );
-    if (ret < 0 || ret >= sizeof(user_msg)) {
+    if (ret < 0 || ret > bufsize) {
         D(("snprintf failed."));
+
+        free(user_msg);
         return PAM_SYSTEM_ERR;
     }
 
     ret = do_pam_conversation(pamh, PAM_TEXT_INFO, user_msg, NULL, NULL);
+    free(user_msg);
     if (ret != PAM_SUCCESS) {
         D(("do_pam_conversation failed."));
+
         return PAM_SYSTEM_ERR;
     }