Accepting request 230928 from home:namtrac:bugfix
- Add fix-curve25519-kex.patch to fix a key-exchange problem with curve25519-sha256@libssh.org, see http://marc.info/?l=openssh-unix-dev&m=139797807804698&w=2 OBS-URL: https://build.opensuse.org/request/show/230928 OBS-URL: https://build.opensuse.org/package/show/network/openssh?expand=0&rev=79
This commit is contained in:
Andrey Karepin
Git OBS Bridge
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commit
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136
fix-curve25519-kex.patch
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136
fix-curve25519-kex.patch
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@ -0,0 +1,136 @@
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Hi,
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So I screwed up when writing the support for the curve25519 KEX method
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that doesn't depend on OpenSSL's BIGNUM type - a bug in my code left
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leading zero bytes where they should have been skipped. The impact of
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this is that OpenSSH 6.5 and 6.6 will fail during key exchange with a
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peer that implements curve25519-sha256@libssh.org properly about 0.2%
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of the time (one in every 512ish connections).
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We've fixed this for OpenSSH 6.7 by avoiding the curve25519-sha256
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key exchange for previous versions, but I'd recommend distributors
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of OpenSSH apply this patch so the affected code doesn't become
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too entrenched in LTS releases.
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The patch fixes the bug and makes OpenSSH identify itself as 6.6.1 so as
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to distinguish itself from the incorrect versions so the compatibility
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code to disable the affected KEX isn't activated.
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I've committed this on the 6.6 branch too.
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Apologies for the hassle.
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-d
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Index: version.h
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===================================================================
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--- version.h.orig
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+++ version.h
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@@ -1,6 +1,6 @@
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/* $OpenBSD: version.h,v 1.70 2014/02/27 22:57:40 djm Exp $ */
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-#define SSH_VERSION "OpenSSH_6.6"
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+#define SSH_VERSION "OpenSSH_6.6.1"
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#define SSH_PORTABLE "p1"
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#define SSH_RELEASE SSH_VERSION SSH_PORTABLE
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Index: compat.c
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===================================================================
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--- compat.c.orig
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+++ compat.c
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@@ -95,6 +95,9 @@ compat_datafellows(const char *version)
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{ "Sun_SSH_1.0*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF},
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{ "OpenSSH_4*", 0 },
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{ "OpenSSH_5*", SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT},
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+ { "OpenSSH_6.6.1*", SSH_NEW_OPENSSH},
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+ { "OpenSSH_6.5*,"
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+ "OpenSSH_6.6*", SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD},
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{ "OpenSSH*", SSH_NEW_OPENSSH },
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{ "*MindTerm*", 0 },
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{ "2.1.0*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
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@@ -251,7 +254,6 @@ compat_cipher_proposal(char *cipher_prop
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return cipher_prop;
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}
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-
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char *
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compat_pkalg_proposal(char *pkalg_prop)
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{
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@@ -265,3 +267,16 @@ compat_pkalg_proposal(char *pkalg_prop)
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return pkalg_prop;
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}
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+char *
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+compat_kex_proposal(char *kex_prop)
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+{
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+ if (!(datafellows & SSH_BUG_CURVE25519PAD))
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+ return kex_prop;
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+ debug2("%s: original KEX proposal: %s", __func__, kex_prop);
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+ kex_prop = filter_proposal(kex_prop, "curve25519-sha256@libssh.org");
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+ debug2("%s: compat KEX proposal: %s", __func__, kex_prop);
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+ if (*kex_prop == '\0')
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+ fatal("No supported key exchange algorithms found");
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+ return kex_prop;
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+}
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+
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Index: compat.h
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===================================================================
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--- compat.h.orig
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+++ compat.h
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@@ -59,6 +59,7 @@
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#define SSH_BUG_RFWD_ADDR 0x02000000
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#define SSH_NEW_OPENSSH 0x04000000
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#define SSH_BUG_DYNAMIC_RPORT 0x08000000
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+#define SSH_BUG_CURVE25519PAD 0x10000000
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void enable_compat13(void);
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void enable_compat20(void);
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@@ -66,6 +67,7 @@ void compat_datafellows(const char *
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int proto_spec(const char *);
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char *compat_cipher_proposal(char *);
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char *compat_pkalg_proposal(char *);
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+char *compat_kex_proposal(char *);
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extern int compat13;
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extern int compat20;
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Index: sshd.c
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===================================================================
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--- sshd.c.orig
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+++ sshd.c
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@@ -2675,6 +2675,9 @@ do_ssh2_kex(void)
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if (options.kex_algorithms != NULL)
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myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
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+ myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
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+ myproposal[PROPOSAL_KEX_ALGS]);
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+
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if (options.rekey_limit || options.rekey_interval)
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packet_set_rekey_limits((u_int32_t)options.rekey_limit,
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(time_t)options.rekey_interval);
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Index: sshconnect2.c
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===================================================================
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--- sshconnect2.c.orig
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+++ sshconnect2.c
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@@ -232,6 +232,8 @@ ssh_kex2(char *host, struct sockaddr *ho
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}
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if (options.kex_algorithms != NULL)
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myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
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+ myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
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+ myproposal[PROPOSAL_KEX_ALGS]);
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#ifdef GSSAPI
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/* If we've got GSSAPI algorithms, then we also support the
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Index: bufaux.c
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===================================================================
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--- bufaux.c.orig
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+++ bufaux.c
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@@ -372,6 +372,9 @@ buffer_put_bignum2_from_string(Buffer *b
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if (l > 8 * 1024)
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fatal("%s: length %u too long", __func__, l);
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+ /* Skip leading zero bytes */
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+ for (; l > 0 && *s == 0; l--, s++)
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+ ;
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p = buf = xmalloc(l + 1);
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/*
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* If most significant bit is set then prepend a zero byte to
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@ -1,3 +1,10 @@
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-------------------------------------------------------------------
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Mon Apr 21 08:46:58 UTC 2014 - idonmez@suse.com
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- Add fix-curve25519-kex.patch to fix a key-exchange problem
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with curve25519-sha256@libssh.org, see
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http://marc.info/?l=openssh-unix-dev&m=139797807804698&w=2
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-------------------------------------------------------------------
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Tue Apr 15 09:26:16 UTC 2014 - rhafer@suse.com
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@ -147,6 +147,7 @@ Patch36: openssh-6.6p1-seccomp_getuid.patch
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Patch37: openssh-6.6p1-X_forward_with_disabled_ipv6.patch
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Patch38: openssh-6.6p1-fips-checks.patch
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Patch39: openssh-6.6p1-ldap.patch
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Patch40: fix-curve25519-kex.patch
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BuildRoot: %{_tmppath}/%{name}-%{version}-build
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%description
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@ -221,6 +222,7 @@ cryptomodule.
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%patch37 -p2
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%patch38 -p2
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%patch39 -p2
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%patch40 -p0
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cp %{SOURCE3} %{SOURCE4} .
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%build
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