upstream: Allow prepending a list of algorithms to the default set

by starting the list with the '^' character, e.g.

HostKeyAlgorithms ^ssh-ed25519
Ciphers ^aes128-gcm@openssh.com,aes256-gcm@openssh.com

ok djm@ dtucker@

OpenBSD-Commit-ID: 1e1996fac0dc8a4b0d0ff58395135848287f6f97

1 files changed, 9 insertions, 5 deletions

diff --git a/readconf.c b/readconf.c
index d1b7871ec..f78b4d6fe 100644
--- a/readconf.c
+++ b/readconf.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.c,v 1.308 2019/08/09 05:05:54 djm Exp $ */
+/* $OpenBSD: readconf.c,v 1.309 2019/09/06 14:45:34 naddy Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1199,7 +1199,8 @@ parse_int:
                 arg = strdelim(&s);
                 if (!arg || *arg == '\0')
                         fatal("%.200s line %d: Missing argument.", filename, linenum);
-                if (*arg != '-' && !ciphers_valid(*arg == '+' ? arg + 1 : arg))
+                if (*arg != '-' &&
+                    !ciphers_valid(*arg == '+' || *arg == '^' ? arg + 1 : arg))
                         fatal("%.200s line %d: Bad SSH2 cipher spec '%s'.",
                             filename, linenum, arg ? arg : "<NONE>");
                 if (*activep && options->ciphers == NULL)
@@ -1210,7 +1211,8 @@ parse_int:
                 arg = strdelim(&s);
                 if (!arg || *arg == '\0')
                         fatal("%.200s line %d: Missing argument.", filename, linenum);
-                if (*arg != '-' && !mac_valid(*arg == '+' ? arg + 1 : arg))
+                if (*arg != '-' &&
+                    !mac_valid(*arg == '+' || *arg == '^' ? arg + 1 : arg))
                         fatal("%.200s line %d: Bad SSH2 MAC spec '%s'.",
                             filename, linenum, arg ? arg : "<NONE>");
                 if (*activep && options->macs == NULL)
@@ -1223,7 +1225,8 @@ parse_int:
                         fatal("%.200s line %d: Missing argument.",
                             filename, linenum);
                 if (*arg != '-' &&
-                    !kex_names_valid(*arg == '+' ? arg + 1 : arg))
+                    !kex_names_valid(*arg == '+' || *arg == '^' ?
+                    arg + 1 : arg))
                         fatal("%.200s line %d: Bad SSH2 KexAlgorithms '%s'.",
                             filename, linenum, arg ? arg : "<NONE>");
                 if (*activep && options->kex_algorithms == NULL)
@@ -1238,7 +1241,8 @@ parse_keytypes:
                         fatal("%.200s line %d: Missing argument.",
                             filename, linenum);
                 if (*arg != '-' &&
-                    !sshkey_names_valid2(*arg == '+' ? arg + 1 : arg, 1))
+                    !sshkey_names_valid2(*arg == '+' || *arg == '^' ?
+                    arg + 1 : arg, 1))
                         fatal("%s line %d: Bad key types '%s'.",
                                 filename, linenum, arg ? arg : "<NONE>");
                 if (*activep && *charptr == NULL)