forked from rpms/openssh
Update minimize-sha1-use.patch to use upstream code
Related: rhbz#2031868, rhbz#2064338 Signed-off-by: Zoltan Fridrich <zfridric@redhat.com>
This commit is contained in:
Zoltan Fridrich
parent
cf05a27ed6
commit
abf0321b6d
@ -1,102 +1,194 @@
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diff -up openssh-8.7p1/kex.c.minsha1 openssh-8.7p1/kex.c
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--- openssh-8.7p1/kex.c.minsha1 2021-12-20 17:38:51.438294309 +0100
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+++ openssh-8.7p1/kex.c 2021-12-21 11:02:48.379991319 +0100
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@@ -994,6 +994,35 @@ kex_choose_conf(struct ssh *ssh)
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diff --color -ru a/clientloop.c b/clientloop.c
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--- a/clientloop.c 2022-06-29 16:35:06.677597259 +0200
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+++ b/clientloop.c 2022-06-29 16:40:29.737926205 +0200
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@@ -116,6 +116,9 @@
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#include "ssh-gss.h"
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#endif
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+/* Permitted RSA signature algorithms for UpdateHostkeys proofs */
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+#define HOSTKEY_PROOF_RSA_ALGS "rsa-sha2-512,rsa-sha2-256"
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+
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/* import options */
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extern Options options;
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@@ -2110,8 +2113,10 @@
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struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
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size_t i, ndone;
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struct sshbuf *signdata;
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- int r, kexsigtype, use_kexsigtype;
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+ int r, plaintype;
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const u_char *sig;
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+ const char *rsa_kexalg = NULL;
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+ char *alg = NULL;
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size_t siglen;
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if (ctx->nnew == 0)
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@@ -2122,9 +2127,9 @@
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hostkeys_update_ctx_free(ctx);
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return;
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}
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- kexsigtype = sshkey_type_plain(
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- sshkey_type_from_name(ssh->kex->hostkey_alg));
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-
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+ if (sshkey_type_plain(sshkey_type_from_name(
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+ ssh->kex->hostkey_alg)) == KEY_RSA)
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+ rsa_kexalg = ssh->kex->hostkey_alg;
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if ((signdata = sshbuf_new()) == NULL)
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fatal_f("sshbuf_new failed");
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/*
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@@ -2135,6 +2140,7 @@
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for (ndone = i = 0; i < ctx->nkeys; i++) {
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if (ctx->keys_match[i])
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continue;
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+ plaintype = sshkey_type_plain(ctx->keys[i]->type);
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/* Prepare data to be signed: session ID, unique string, key */
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sshbuf_reset(signdata);
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if ( (r = sshbuf_put_cstring(signdata,
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@@ -2148,19 +2154,33 @@
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error_fr(r, "parse sig");
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goto out;
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}
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+ if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) {
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+ error_fr(r, "server gave unintelligible signature "
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+ "for %s key %zu", sshkey_type(ctx->keys[i]), i);
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+ goto out;
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+ }
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/*
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- * For RSA keys, prefer to use the signature type negotiated
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- * during KEX to the default (SHA1).
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+ * Special case for RSA keys: if a RSA hostkey was negotiated,
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+ * then use its signature type for verification of RSA hostkey
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+ * proofs. Otherwise, accept only RSA-SHA256/512 signatures.
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*/
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- use_kexsigtype = kexsigtype == KEY_RSA &&
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- sshkey_type_plain(ctx->keys[i]->type) == KEY_RSA;
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- debug3_f("verify %s key %zu using %s sigalg",
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- sshkey_type(ctx->keys[i]), i,
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- use_kexsigtype ? ssh->kex->hostkey_alg : "default");
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+ if (plaintype == KEY_RSA && rsa_kexalg == NULL &&
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+ match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) {
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+ debug_f("server used untrusted RSA signature algorithm "
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+ "%s for key %zu, disregarding", alg, i);
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+ free(alg);
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+ /* zap the key from the list */
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+ sshkey_free(ctx->keys[i]);
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+ ctx->keys[i] = NULL;
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+ ndone++;
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+ continue;
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+ }
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+ debug3_f("verify %s key %zu using sigalg %s",
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+ sshkey_type(ctx->keys[i]), i, alg);
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+ free(alg);
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if ((r = sshkey_verify(ctx->keys[i], sig, siglen,
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sshbuf_ptr(signdata), sshbuf_len(signdata),
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- use_kexsigtype ? ssh->kex->hostkey_alg : NULL, 0,
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- NULL)) != 0) {
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+ plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) {
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error_fr(r, "server gave bad signature for %s key %zu",
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sshkey_type(ctx->keys[i]), i);
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goto out;
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diff --color -ru a/kex.c b/kex.c
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--- a/kex.c 2022-06-29 16:35:06.775599179 +0200
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+++ b/kex.c 2022-06-29 16:42:00.839710940 +0200
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@@ -959,6 +959,18 @@
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return (1);
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}
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+/* returns non-zero if proposal contains any algorithm from algs */
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+static int
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+has_any_alg(const char *proposal, const char *algs)
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+{
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+ char *cp;
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+
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+ if ((cp = match_list(proposal, algs, NULL)) == NULL)
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+ return 0;
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+ free(cp);
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+ return 1;
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+}
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+
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static int
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kex_choose_conf(struct ssh *ssh)
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{
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@@ -994,6 +1006,16 @@
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free(ext);
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}
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+ /* Check whether client supports rsa-sha2 algorithms */
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+ if (kex->server && (kex->flags & KEX_INITIAL)) {
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+ char *ext;
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+
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+ ext = match_list("rsa-sha2-256", peer[PROPOSAL_SERVER_HOST_KEY_ALGS], NULL);
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+ if (ext) {
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+ if (has_any_alg(peer[PROPOSAL_SERVER_HOST_KEY_ALGS],
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+ "rsa-sha2-256,rsa-sha2-256-cert-v01@openssh.com"))
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+ kex->flags |= KEX_RSA_SHA2_256_SUPPORTED;
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+ free(ext);
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+ }
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+
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+ ext = match_list("rsa-sha2-512", peer[PROPOSAL_SERVER_HOST_KEY_ALGS], NULL);
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+ if (ext) {
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+ if (has_any_alg(peer[PROPOSAL_SERVER_HOST_KEY_ALGS],
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+ "rsa-sha2-512,rsa-sha2-512-cert-v01@openssh.com"))
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+ kex->flags |= KEX_RSA_SHA2_512_SUPPORTED;
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+ free(ext);
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+ }
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+
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+ ext = match_list("rsa-sha2-256-cert-v01@openssh.com", peer[PROPOSAL_SERVER_HOST_KEY_ALGS], NULL);
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+ if (ext) {
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+ kex->flags |= KEX_RSA_SHA2_256_SUPPORTED;
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+ free(ext);
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+ }
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+
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+ ext = match_list("rsa-sha2-512-cert-v01@openssh.com", peer[PROPOSAL_SERVER_HOST_KEY_ALGS], NULL);
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+ if (ext) {
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+ kex->flags |= KEX_RSA_SHA2_512_SUPPORTED;
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+ free(ext);
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+ }
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+ }
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+
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/* Algorithm Negotiation */
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if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
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sprop[PROPOSAL_KEX_ALGS])) != 0) {
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diff -up openssh-8.7p1/kex.h.minsha1 openssh-8.7p1/kex.h
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--- openssh-8.7p1/kex.h.minsha1 2021-12-20 17:38:51.430294240 +0100
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+++ openssh-8.7p1/kex.h 2021-12-21 10:56:29.066735608 +0100
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@@ -116,6 +116,8 @@ enum kex_exchange {
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diff --color -ru a/kex.h b/kex.h
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--- a/kex.h 2022-06-29 16:35:06.766599003 +0200
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+++ b/kex.h 2022-06-29 16:42:24.199168567 +0200
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@@ -116,6 +116,8 @@
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#define KEX_INIT_SENT 0x0001
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#define KEX_INITIAL 0x0002
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+#define KEX_RSA_SHA2_256_SUPPORTED 0x0004
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+#define KEX_RSA_SHA2_512_SUPPORTED 0x0008
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+#define KEX_RSA_SHA2_256_SUPPORTED 0x0008 /* only set in server for now */
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+#define KEX_RSA_SHA2_512_SUPPORTED 0x0010 /* only set in server for now */
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struct sshenc {
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char *name;
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diff -up openssh-8.7p1/serverloop.c.minsha1 openssh-8.7p1/serverloop.c
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--- openssh-8.7p1/serverloop.c.minsha1 2021-08-20 06:03:49.000000000 +0200
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+++ openssh-8.7p1/serverloop.c 2021-12-21 11:01:00.594047538 +0100
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@@ -684,7 +685,7 @@ server_input_hostkeys_prove(struct ssh *
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diff --color -ru a/serverloop.c b/serverloop.c
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--- a/serverloop.c 2021-08-20 06:03:49.000000000 +0200
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+++ b/serverloop.c 2022-06-29 16:45:05.902336428 +0200
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@@ -684,16 +684,18 @@
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struct sshbuf *resp = NULL;
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struct sshbuf *sigbuf = NULL;
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struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
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- int r, ndx, kexsigtype, use_kexsigtype, success = 0;
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+ int r, ndx, success = 0;
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const u_char *blob;
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+ const char *sigalg, *kex_rsa_sigalg = NULL;
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u_char *sig = 0;
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size_t blen, slen;
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@@ -692,9 +693,11 @@ server_input_hostkeys_prove(struct ssh *
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if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
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fatal_f("sshbuf_new");
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- kexsigtype = sshkey_type_plain(
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- sshkey_type_from_name(ssh->kex->hostkey_alg));
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+ if (sshkey_type_plain(sshkey_type_from_name(
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+ ssh->kex->hostkey_alg)) == KEY_RSA)
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+ kex_rsa_sigalg = ssh->kex->hostkey_alg;
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while (ssh_packet_remaining(ssh) > 0) {
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+ const char *pkexstr = NULL;
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+ const char *rsa_sha2_256 = "rsa-sha2-256";
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+ const char *rsa_sha2_512 = "rsa-sha2-512";
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+
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sshkey_free(key);
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key = NULL;
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if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 ||
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@@ -726,8 +729,13 @@ server_input_hostkeys_prove(struct ssh *
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@@ -726,16 +728,24 @@
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* For RSA keys, prefer to use the signature type negotiated
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* during KEX to the default (SHA1).
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*/
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- use_kexsigtype = kexsigtype == KEY_RSA &&
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- sshkey_type_plain(key->type) == KEY_RSA;
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+ sigalg = NULL;
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+ if (sshkey_type_plain(key->type) == KEY_RSA) {
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+ if (ssh->kex->flags & KEX_RSA_SHA2_512_SUPPORTED)
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+ pkexstr = rsa_sha2_512;
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+ else if (ssh->kex->flags & KEX_RSA_SHA2_256_SUPPORTED)
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+ pkexstr = rsa_sha2_256;
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+ if (kex_rsa_sigalg != NULL)
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+ sigalg = kex_rsa_sigalg;
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+ else if (ssh->kex->flags & KEX_RSA_SHA2_512_SUPPORTED)
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+ sigalg = "rsa-sha2-512";
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+ else if (ssh->kex->flags & KEX_RSA_SHA2_256_SUPPORTED)
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+ sigalg = "rsa-sha2-256";
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+ }
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+
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+ debug3_f("sign %s key (index %d) using sigalg %s",
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+ sshkey_type(key), ndx, sigalg == NULL ? "default" : sigalg);
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if ((r = sshbuf_put_cstring(sigbuf,
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"hostkeys-prove-00@openssh.com")) != 0 ||
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(r = sshbuf_put_stringb(sigbuf,
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@@ -735,7 +743,7 @@ server_input_hostkeys_prove(struct ssh *
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ssh->kex->session_id)) != 0 ||
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(r = sshkey_puts(key, sigbuf)) != 0 ||
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(r = ssh->kex->sign(ssh, key_prv, key_pub, &sig, &slen,
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sshbuf_ptr(sigbuf), sshbuf_len(sigbuf),
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- sshbuf_ptr(sigbuf), sshbuf_len(sigbuf),
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- use_kexsigtype ? ssh->kex->hostkey_alg : NULL)) != 0 ||
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+ pkexstr)) != 0 ||
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+ sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), sigalg)) != 0 ||
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(r = sshbuf_put_string(resp, sig, slen)) != 0) {
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error_fr(r, "assemble signature");
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goto out;
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13
openssh.spec
13
openssh.spec
@ -51,7 +51,7 @@
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# Do not forget to bump pam_ssh_agent_auth release if you rewind the main package release to 1
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%global openssh_ver 8.7p1
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%global openssh_rel 8
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%global openssh_rel 9
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%global pam_ssh_agent_ver 0.10.4
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%global pam_ssh_agent_rel 4
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@ -212,7 +212,10 @@ Patch980: openssh-8.7p1-sftpscp-dir-create.patch
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# https://github.com/openssh/openssh-portable/pull/299
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# downstream only
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Patch981: openssh-8.7p1-recursive-scp.patch
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# Minimize the use of SHA1 as a proof of possession for RSA key (#2031868)
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# upstream commits:
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# 291721bc7c840d113a49518f3fca70e86248b8e8
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# 0fa33683223c76289470a954404047bc762be84c
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Patch1000: openssh-8.7p1-minimize-sha1-use.patch
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License: BSD
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@ -400,7 +403,7 @@ popd
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%patch201 -p1 -b .audit-race
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%patch700 -p1 -b .fips
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%patch1000 -p1 -b .minsha1
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%patch1000 -p1 -b .minimize-sha1-use
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%patch100 -p1 -b .coverity
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@ -681,6 +684,10 @@ test -f %{sysconfig_anaconda} && \
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%endif
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%changelog
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* Wed Jun 29 2022 Zoltan Fridrich <zfridric@redhat.com> - 8.7p1-9
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- Update minimize-sha1-use.patch to use upstream code
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Related: rhbz#2031868
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* Mon Feb 21 2022 Dmitry Belyavskiy <dbelyavs@redhat.com> - 8.7p1-8
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- Workaround for RHEL 8 incompatibility in scp utility in SFTP mode
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Related: rhbz#2038854
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