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upstream: Always return allocated strings from the kex filtering so 

that we can free them later.  Fix one leak in compat_kex_proposal.  Based on
github PR#324 from ZoltanFridrich with some simplications by me. ok djm@

OpenBSD-Commit-ID: 9171616da3307612d0ede086fd511142f91246e4
This commit is contained in:
dtucker@openbsd.org 2022-07-01 03:35:45 +00:00 committed by Damien Miller
parent 96faa0de6c
commit 486c4dc3b8
1 changed files with 11 additions and 4 deletions
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15
compat.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: compat.c,v 1.119 2021/09/10 05:46:09 djm Exp $ */
/* $OpenBSD: compat.c,v 1.120 2022/07/01 03:35:45 dtucker Exp $ */
/*
* Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
*
@ -156,11 +156,12 @@ compat_banner(struct ssh *ssh, const char *version)
debug_f("no match: %s", version);
}
/* Always returns pointer to allocated memory, caller must free. */
char *
compat_cipher_proposal(struct ssh *ssh, char *cipher_prop)
{
if (!(ssh->compat & SSH_BUG_BIGENDIANAES))
return cipher_prop;
return xstrdup(cipher_prop);
debug2_f("original cipher proposal: %s", cipher_prop);
if ((cipher_prop = match_filter_denylist(cipher_prop, "aes*")) == NULL)
fatal("match_filter_denylist failed");
@ -170,11 +171,12 @@ compat_cipher_proposal(struct ssh *ssh, char *cipher_prop)
return cipher_prop;
}
/* Always returns pointer to allocated memory, caller must free. */
char *
compat_pkalg_proposal(struct ssh *ssh, char *pkalg_prop)
{
if (!(ssh->compat & SSH_BUG_RSASIGMD5))
return pkalg_prop;
return xstrdup(pkalg_prop);
debug2_f("original public key proposal: %s", pkalg_prop);
if ((pkalg_prop = match_filter_denylist(pkalg_prop, "ssh-rsa")) == NULL)
fatal("match_filter_denylist failed");
@ -184,21 +186,26 @@ compat_pkalg_proposal(struct ssh *ssh, char *pkalg_prop)
return pkalg_prop;
}
/* Always returns pointer to allocated memory, caller must free. */
char *
compat_kex_proposal(struct ssh *ssh, char *p)
{
char *cp = NULL;
if ((ssh->compat & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
return p;
return xstrdup(p);
debug2_f("original KEX proposal: %s", p);
if ((ssh->compat & SSH_BUG_CURVE25519PAD) != 0)
if ((p = match_filter_denylist(p,
"curve25519-sha256@libssh.org")) == NULL)
fatal("match_filter_denylist failed");
if ((ssh->compat & SSH_OLD_DHGEX) != 0) {
cp = p;
if ((p = match_filter_denylist(p,
"diffie-hellman-group-exchange-sha256,"
"diffie-hellman-group-exchange-sha1")) == NULL)
fatal("match_filter_denylist failed");
free(cp);
}
debug2_f("compat KEX proposal: %s", p);
if (*p == '\0')