diff -up openssh-6.6p1/gss-genr.c.gsskexalg openssh-6.6p1/gss-genr.c --- openssh-6.6p1/gss-genr.c.gsskexalg 2015-08-14 16:07:33.271343064 +0200 +++ openssh-6.6p1/gss-genr.c 2015-08-14 16:07:33.338342936 +0200 @@ -76,7 +76,8 @@ ssh_gssapi_oid_table_ok() { */ char * -ssh_gssapi_client_mechanisms(const char *host, const char *client) { +ssh_gssapi_client_mechanisms(const char *host, const char *client, + const char *kex) { gss_OID_set gss_supported; OM_uint32 min_status; @@ -84,12 +85,12 @@ ssh_gssapi_client_mechanisms(const char return NULL; return(ssh_gssapi_kex_mechs(gss_supported, ssh_gssapi_check_mechanism, - host, client)); + host, client, kex)); } char * ssh_gssapi_kex_mechs(gss_OID_set gss_supported, ssh_gssapi_check_fn *check, - const char *host, const char *client) { + const char *host, const char *client, const char *kex) { Buffer buf; size_t i; int oidpos, enclen; @@ -98,6 +99,7 @@ ssh_gssapi_kex_mechs(gss_OID_set gss_sup char deroid[2]; const EVP_MD *evp_md = EVP_md5(); EVP_MD_CTX md; + char *s, *cp, *p; if (gss_enc2oid != NULL) { for (i = 0; gss_enc2oid[i].encoded != NULL; i++) @@ -111,6 +113,7 @@ ssh_gssapi_kex_mechs(gss_OID_set gss_sup buffer_init(&buf); oidpos = 0; + s = cp = xstrdup(kex); for (i = 0; i < gss_supported->count; i++) { if (gss_supported->elements[i].length < 128 && (*check)(NULL, &(gss_supported->elements[i]), host, client)) { @@ -129,26 +132,22 @@ ssh_gssapi_kex_mechs(gss_OID_set gss_sup enclen = __b64_ntop(digest, EVP_MD_size(evp_md), encoded, EVP_MD_size(evp_md) * 2); - if (oidpos != 0) - buffer_put_char(&buf, ','); - - buffer_append(&buf, KEX_GSS_GEX_SHA1_ID, - sizeof(KEX_GSS_GEX_SHA1_ID) - 1); - buffer_append(&buf, encoded, enclen); - buffer_put_char(&buf, ','); - buffer_append(&buf, KEX_GSS_GRP1_SHA1_ID, - sizeof(KEX_GSS_GRP1_SHA1_ID) - 1); - buffer_append(&buf, encoded, enclen); - buffer_put_char(&buf, ','); - buffer_append(&buf, KEX_GSS_GRP14_SHA1_ID, - sizeof(KEX_GSS_GRP14_SHA1_ID) - 1); - buffer_append(&buf, encoded, enclen); + cp = strncpy(s, kex, strlen(kex)); + for ((p = strsep(&cp, ",")); p && *p != '\0'; + (p = strsep(&cp, ","))) { + if (buffer_len(&buf) != 0) + buffer_put_char(&buf, ','); + buffer_append(&buf, p, + strlen(p)); + buffer_append(&buf, encoded, enclen); + } gss_enc2oid[oidpos].oid = &(gss_supported->elements[i]); gss_enc2oid[oidpos].encoded = encoded; oidpos++; } } + free(s); gss_enc2oid[oidpos].oid = NULL; gss_enc2oid[oidpos].encoded = NULL; diff -up openssh-6.6p1/gss-serv.c.gsskexalg openssh-6.6p1/gss-serv.c --- openssh-6.6p1/gss-serv.c.gsskexalg 2015-08-14 16:07:33.296343016 +0200 +++ openssh-6.6p1/gss-serv.c 2015-08-14 16:07:33.338342936 +0200 @@ -151,7 +151,7 @@ ssh_gssapi_server_mechanisms() { ssh_gssapi_supported_oids(&supported); return (ssh_gssapi_kex_mechs(supported, &ssh_gssapi_server_check_mech, - NULL, NULL)); + NULL, NULL, options.gss_kex_algorithms)); } /* Unprivileged */ diff -up openssh-6.6p1/kex.c.gsskexalg openssh-6.6p1/kex.c --- openssh-6.6p1/kex.c.gsskexalg 2015-08-14 16:07:33.271343064 +0200 +++ openssh-6.6p1/kex.c 2015-08-14 16:07:33.339342935 +0200 @@ -160,6 +160,29 @@ kex_names_valid(const char *names) return 1; } +/* Validate GSS KEX method name list */ +int +gss_kex_names_valid(const char *names) +{ + char *s, *cp, *p; + + if (names == NULL || *names == '\0') + return 0; + s = cp = xstrdup(names); + for ((p = strsep(&cp, ",")); p && *p != '\0'; + (p = strsep(&cp, ","))) { + if (strncmp(p, "gss-", 4) != 0 + || kex_alg_by_name(p) == NULL) { + error("Unsupported KEX algorithm \"%.100s\"", p); + free(s); + return 0; + } + } + debug3("gss kex names ok: [%s]", names); + free(s); + return 1; +} + /* put algorithm proposal into buffer */ static void kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) diff -up openssh-6.6p1/readconf.c.gsskexalg openssh-6.6p1/readconf.c --- openssh-6.6p1/readconf.c.gsskexalg 2015-08-14 16:07:33.274343058 +0200 +++ openssh-6.6p1/readconf.c 2015-08-14 16:14:17.600574919 +0200 @@ -55,6 +55,7 @@ #include "kex.h" #include "mac.h" #include "uidswap.h" +#include "ssh-gss.h" /* Format of the configuration file: @@ -142,7 +143,7 @@ typedef enum { oEnableSSHKeysign, oRekeyLimit, oVerifyHostKeyDNS, oConnectTimeout, oAddressFamily, oGssAuthentication, oGssDelegateCreds, oGssTrustDns, oGssKeyEx, oGssClientIdentity, oGssRenewalRekey, - oGssServerIdentity, + oGssServerIdentity, oGssKexAlgorithms, oServerAliveInterval, oServerAliveCountMax, oIdentitiesOnly, oSendEnv, oControlPath, oControlMaster, oControlPersist, oHashKnownHosts, @@ -191,6 +192,7 @@ static struct { { "gssapiclientidentity", oGssClientIdentity }, { "gssapiserveridentity", oGssServerIdentity }, { "gssapirenewalforcesrekey", oGssRenewalRekey }, + { "gssapikexalgorithms", oGssKexAlgorithms }, #else { "gssapiauthentication", oUnsupported }, { "gssapikeyexchange", oUnsupported }, @@ -198,6 +200,7 @@ static struct { { "gssapitrustdns", oUnsupported }, { "gssapiclientidentity", oUnsupported }, { "gssapirenewalforcesrekey", oUnsupported }, + { "gssapikexalgorithms", oUnsupported }, #endif { "fallbacktorsh", oDeprecated }, { "usersh", oDeprecated }, @@ -876,6 +879,18 @@ parse_time: intptr = &options->gss_renewal_rekey; goto parse_flag; + case oGssKexAlgorithms: + arg = strdelim(&s); + if (!arg || *arg == '\0') + fatal("%.200s line %d: Missing argument.", + filename, linenum); + if (!gss_kex_names_valid(arg)) + fatal("%.200s line %d: Bad GSSAPI KexAlgorithms '%s'.", + filename, linenum, arg ? arg : ""); + if (*activep && options->gss_kex_algorithms == NULL) + options->gss_kex_algorithms = xstrdup(arg); + break; + case oBatchMode: intptr = &options->batch_mode; goto parse_flag; @@ -1534,6 +1549,7 @@ initialize_options(Options * options) options->gss_renewal_rekey = -1; options->gss_client_identity = NULL; options->gss_server_identity = NULL; + options->gss_kex_algorithms = NULL; options->password_authentication = -1; options->kbd_interactive_authentication = -1; options->kbd_interactive_devices = NULL; @@ -1660,6 +1676,8 @@ fill_default_options(Options * options) options->gss_trust_dns = 0; if (options->gss_renewal_rekey == -1) options->gss_renewal_rekey = 0; + if (options->gss_kex_algorithms == NULL) + options->gss_kex_algorithms = strdup(GSS_KEX_DEFAULT_KEX); if (options->password_authentication == -1) options->password_authentication = 1; if (options->kbd_interactive_authentication == -1) diff -up openssh-6.6p1/readconf.h.gsskexalg openssh-6.6p1/readconf.h --- openssh-6.6p1/readconf.h.gsskexalg 2015-08-14 16:07:33.274343058 +0200 +++ openssh-6.6p1/readconf.h 2015-08-14 16:07:33.339342935 +0200 @@ -60,6 +60,7 @@ typedef struct { int gss_renewal_rekey; /* Credential renewal forces rekey */ char *gss_client_identity; /* Principal to initiate GSSAPI with */ char *gss_server_identity; /* GSSAPI target principal */ + char *gss_kex_algorithms; /* GSSAPI kex methods to be offered by client. */ int password_authentication; /* Try password * authentication. */ int kbd_interactive_authentication; /* Try keyboard-interactive auth. */ diff -up openssh-6.6p1/servconf.c.gsskexalg openssh-6.6p1/servconf.c --- openssh-6.6p1/servconf.c.gsskexalg 2015-08-14 16:07:45.704319443 +0200 +++ openssh-6.6p1/servconf.c 2015-08-14 16:14:15.306579277 +0200 @@ -54,6 +54,7 @@ #include "packet.h" #include "hostfile.h" #include "auth.h" +#include "ssh-gss.h" static void add_listen_addr(ServerOptions *, char *, int); static void add_one_listen_addr(ServerOptions *, char *, int); @@ -112,6 +113,7 @@ initialize_server_options(ServerOptions options->gss_cleanup_creds = -1; options->gss_strict_acceptor = -1; options->gss_store_rekey = -1; + options->gss_kex_algorithms = NULL; options->password_authentication = -1; options->kbd_interactive_authentication = -1; options->challenge_response_authentication = -1; @@ -258,6 +260,8 @@ fill_default_server_options(ServerOption options->gss_strict_acceptor = 1; if (options->gss_store_rekey == -1) options->gss_store_rekey = 0; + if (options->gss_kex_algorithms == NULL) + options->gss_kex_algorithms = strdup(GSS_KEX_DEFAULT_KEX); if (options->password_authentication == -1) options->password_authentication = 1; if (options->kbd_interactive_authentication == -1) @@ -360,7 +364,7 @@ typedef enum { sHostbasedUsesNameFromPacketOnly, sClientAliveInterval, sClientAliveCountMax, sAuthorizedKeysFile, sGssAuthentication, sGssCleanupCreds, sGssEnablek5users, sGssStrictAcceptor, - sGssKeyEx, sGssStoreRekey, sAcceptEnv, sPermitTunnel, + sGssKeyEx, sGssStoreRekey, sGssKexAlgorithms, sAcceptEnv, sPermitTunnel, sMatch, sPermitOpen, sForceCommand, sChrootDirectory, sUsePrivilegeSeparation, sAllowAgentForwarding, sHostCertificate, @@ -434,6 +438,7 @@ static struct { { "gssapikeyexchange", sGssKeyEx, SSHCFG_GLOBAL }, { "gssapistorecredentialsonrekey", sGssStoreRekey, SSHCFG_GLOBAL }, { "gssapienablek5users", sGssEnablek5users, SSHCFG_ALL }, + { "gssapikexalgorithms", sGssKexAlgorithms, SSHCFG_GLOBAL }, #else { "gssapiauthentication", sUnsupported, SSHCFG_ALL }, { "gssapicleanupcredentials", sUnsupported, SSHCFG_GLOBAL }, @@ -442,6 +447,7 @@ static struct { { "gssapikeyexchange", sUnsupported, SSHCFG_GLOBAL }, { "gssapistorecredentialsonrekey", sUnsupported, SSHCFG_GLOBAL }, { "gssapienablek5users", sUnsupported, SSHCFG_ALL }, + { "gssapikexalgorithms", sUnsupported, SSHCFG_GLOBAL }, #endif { "gssusesessionccache", sUnsupported, SSHCFG_GLOBAL }, { "gssapiusesessioncredcache", sUnsupported, SSHCFG_GLOBAL }, @@ -1137,6 +1143,18 @@ process_server_config_line(ServerOptions intptr = &options->gss_store_rekey; goto parse_flag; + case sGssKexAlgorithms: + arg = strdelim(&cp); + if (!arg || *arg == '\0') + fatal("%.200s line %d: Missing argument.", + filename, linenum); + if (!gss_kex_names_valid(arg)) + fatal("%.200s line %d: Bad GSSAPI KexAlgorithms '%s'.", + filename, linenum, arg ? arg : ""); + if (*activep && options->gss_kex_algorithms == NULL) + options->gss_kex_algorithms = xstrdup(arg); + break; + case sPasswordAuthentication: intptr = &options->password_authentication; goto parse_flag; @@ -2068,6 +2086,7 @@ dump_config(ServerOptions *o) dump_cfg_fmtint(sGssKeyEx, o->gss_keyex); dump_cfg_fmtint(sGssStrictAcceptor, o->gss_strict_acceptor); dump_cfg_fmtint(sGssStoreRekey, o->gss_store_rekey); + dump_cfg_string(sGssKexAlgorithms, o->gss_kex_algorithms); #endif dump_cfg_fmtint(sPasswordAuthentication, o->password_authentication); dump_cfg_fmtint(sKbdInteractiveAuthentication, diff -up openssh-6.6p1/servconf.h.gsskexalg openssh-6.6p1/servconf.h --- openssh-6.6p1/servconf.h.gsskexalg 2015-08-14 16:07:48.160314777 +0200 +++ openssh-6.6p1/servconf.h 2015-08-14 16:09:34.447112854 +0200 @@ -116,6 +116,7 @@ typedef struct { int gss_cleanup_creds; /* If true, destroy cred cache on logout */ int gss_strict_acceptor; /* If true, restrict the GSSAPI acceptor name */ int gss_store_rekey; + char *gss_kex_algorithms; /* GSSAPI kex methods to be offered by client. */ int password_authentication; /* If true, permit password * authentication. */ int kbd_interactive_authentication; /* If true, permit */ diff -up openssh-6.6p1/sshconnect2.c.gsskexalg openssh-6.6p1/sshconnect2.c --- openssh-6.6p1/sshconnect2.c.gsskexalg 2015-08-14 16:07:33.304343001 +0200 +++ openssh-6.6p1/sshconnect2.c 2015-08-14 16:07:33.339342935 +0200 @@ -179,7 +179,8 @@ ssh_kex2(char *host, struct sockaddr *ho else gss_host = host; - gss = ssh_gssapi_client_mechanisms(gss_host, options.gss_client_identity); + gss = ssh_gssapi_client_mechanisms(gss_host, + options.gss_client_identity, options.gss_kex_algorithms); if (gss) { debug("Offering GSSAPI proposal: %s", gss); xasprintf(&myproposal[PROPOSAL_KEX_ALGS], diff -up openssh-6.6p1/ssh-gss.h.gsskexalg openssh-6.6p1/ssh-gss.h --- openssh-6.6p1/ssh-gss.h.gsskexalg 2015-08-14 16:07:33.278343050 +0200 +++ openssh-6.6p1/ssh-gss.h 2015-08-14 16:07:33.340342932 +0200 @@ -76,6 +76,11 @@ extern char **k5users_allowed_cmds; #define KEX_GSS_GRP14_SHA1_ID "gss-group14-sha1-" #define KEX_GSS_GEX_SHA1_ID "gss-gex-sha1-" +#define GSS_KEX_DEFAULT_KEX \ + KEX_GSS_GEX_SHA1_ID "," \ + KEX_GSS_GRP1_SHA1_ID "," \ + KEX_GSS_GRP14_SHA1_ID + typedef struct { char *filename; char *envvar; @@ -147,9 +152,9 @@ int ssh_gssapi_credentials_updated(Gssct /* In the server */ typedef int ssh_gssapi_check_fn(Gssctxt **, gss_OID, const char *, const char *); -char *ssh_gssapi_client_mechanisms(const char *, const char *); +char *ssh_gssapi_client_mechanisms(const char *, const char *, const char *); char *ssh_gssapi_kex_mechs(gss_OID_set, ssh_gssapi_check_fn *, const char *, - const char *); + const char *, const char *); gss_OID ssh_gssapi_id_kex(Gssctxt *, char *, int); int ssh_gssapi_server_check_mech(Gssctxt **,gss_OID, const char *, const char *); diff --git a/ssh.1 b/ssh.1 index 4a7d1cd..c795c40 100644 --- a/ssh.1 +++ b/ssh.1 @@ -449,6 +449,7 @@ For full details of the options listed below, and their possible values, see .It GSSAPIDelegateCredentials .It GSSAPIRenewalForcesRekey .It GSSAPITrustDns +.It GSSAPIKexAlgorithms .It HashKnownHosts .It Host .It HostbasedAuthentication diff --git a/ssh_config.5 b/ssh_config.5 index c95fda6..a2af9c4 100644 --- a/ssh_config.5 +++ b/ssh_config.5 @@ -719,6 +719,18 @@ command line will be passed untouched to the GSSAPI library. The default is .Dq no . This option only applies to protocol version 2 connections using GSSAPI. +.It Cm GSSAPIKexAlgorithms +The list of key exchange algorithms that are offered for GSSAPI +key exchange. Possible values are +.Bd -literal -offset 3n +gss-gex-sha1-, +gss-group1-sha1-, +gss-group14-sha1- +.Ed +.Pp +The default is +.Dq gss-gex-sha1-,gss-group1-sha1-,gss-group14-sha1- . +This option only applies to protocol version 2 connections using GSSAPI. .It Cm HashKnownHosts Indicates that .Xr ssh 1 diff --git a/sshd_config.5 b/sshd_config.5 index 5e8c6c6..4c670aa 100644 --- a/sshd_config.5 +++ b/sshd_config.5 @@ -545,6 +545,18 @@ Controls whether the user's GSSAPI credentials should be updated following a successful connection rekeying. This option can be used to accepted renewed or updated credentials from a compatible client. The default is .Dq no . +.It Cm GSSAPIKexAlgorithms +The list of key exchange algorithms that are accepted by GSSAPI +key exchange. Possible values are +.Bd -literal -offset 3n +gss-gex-sha1-, +gss-group1-sha1-, +gss-group14-sha1- +.Ed +.Pp +The default is +.Dq gss-gex-sha1-,gss-group1-sha1-,gss-group14-sha1- . +This option only applies to protocol version 2 connections using GSSAPI. .It Cm HostbasedAuthentication Specifies whether rhosts or /etc/hosts.equiv authentication together with successful public key client host authentication is allowed