X-Git-Url: http://andersk.mit.edu/gitweb/gssapi-openssh.git/blobdiff_plain/430fc91e16fe0e463995202d99057d8f70773ff2..d9ae70c5856554c6c874b8c12980fff3a32a454a:/openssh/gss-serv.c diff --git a/openssh/gss-serv.c b/openssh/gss-serv.c index 79c86e8..749ed0f 100644 --- a/openssh/gss-serv.c +++ b/openssh/gss-serv.c @@ -1,7 +1,7 @@ -/* $OpenBSD: gss-serv.c,v 1.5 2003/11/17 11:06:07 markus Exp $ */ +/* $OpenBSD: gss-serv.c,v 1.22 2008/05/08 12:02:23 djm Exp $ */ /* - * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. + * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -28,32 +28,39 @@ #ifdef GSSAPI +#include +#include + +#include +#include +#include + +#include "openbsd-compat/sys-queue.h" +#include "xmalloc.h" #include "buffer.h" -#include "bufaux.h" -#include "compat.h" -#include -#include "kex.h" +#include "key.h" +#include "hostfile.h" #include "auth.h" #include "log.h" #include "channels.h" #include "session.h" +#include "misc.h" #include "servconf.h" -#include "monitor_wrap.h" -#include "xmalloc.h" -#include "getput.h" +#include "uidswap.h" +#include "xmalloc.h" #include "ssh-gss.h" +#include "monitor_wrap.h" extern ServerOptions options; -extern u_char *session_id2; -extern int session_id2_len; +extern Authctxt *the_authctxt; static ssh_gssapi_client gssapi_client = { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, - GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}}; + GSS_C_NO_CREDENTIAL, GSS_C_NO_NAME, NULL, {NULL, NULL, NULL}, 0, 0}; ssh_gssapi_mech gssapi_null_mech = - { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; + { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL, NULL}; #ifdef KRB5 extern ssh_gssapi_mech gssapi_kerberos_mech; @@ -76,7 +83,83 @@ ssh_gssapi_mech* supported_mechs[]= { static int limited = 0; #endif -/* Unpriviledged */ +/* + * Acquire credentials for a server running on the current host. + * Requires that the context structure contains a valid OID + */ + +/* Returns a GSSAPI error code */ +/* Privileged (called from ssh_gssapi_server_ctx) */ +static OM_uint32 +ssh_gssapi_acquire_cred(Gssctxt *ctx) +{ + OM_uint32 status; + char lname[MAXHOSTNAMELEN]; + gss_OID_set oidset; + + if (options.gss_strict_acceptor) { + gss_create_empty_oid_set(&status, &oidset); + gss_add_oid_set_member(&status, ctx->oid, &oidset); + + if (gethostname(lname, MAXHOSTNAMELEN)) { + gss_release_oid_set(&status, &oidset); + return (-1); + } + + if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) { + gss_release_oid_set(&status, &oidset); + return (ctx->major); + } + + if ((ctx->major = gss_acquire_cred(&ctx->minor, + ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, + NULL, NULL))) + ssh_gssapi_error(ctx); + + gss_release_oid_set(&status, &oidset); + return (ctx->major); + } else { + ctx->name = GSS_C_NO_NAME; + ctx->creds = GSS_C_NO_CREDENTIAL; + } + return GSS_S_COMPLETE; +} + +/* Privileged */ +OM_uint32 +ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid) +{ + if (*ctx) + ssh_gssapi_delete_ctx(ctx); + ssh_gssapi_build_ctx(ctx); + ssh_gssapi_set_oid(*ctx, oid); + return (ssh_gssapi_acquire_cred(*ctx)); +} + +/* Unprivileged */ +char * +ssh_gssapi_server_mechanisms() { + gss_OID_set supported; + + ssh_gssapi_supported_oids(&supported); + return (ssh_gssapi_kex_mechs(supported, &ssh_gssapi_server_check_mech, + NULL, NULL)); +} + +/* Unprivileged */ +int +ssh_gssapi_server_check_mech(Gssctxt **dum, gss_OID oid, const char *data, + const char *dummy) { + Gssctxt *ctx = NULL; + int res; + + res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid))); + ssh_gssapi_delete_ctx(&ctx); + + return (res); +} + +/* Unprivileged */ void ssh_gssapi_supported_oids(gss_OID_set *oidset) { @@ -86,8 +169,10 @@ ssh_gssapi_supported_oids(gss_OID_set *oidset) gss_OID_set supported; gss_create_empty_oid_set(&min_status, oidset); - /* Ask priviledged process what mechanisms it supports. */ - PRIVSEP(gss_indicate_mechs(&min_status, &supported)); + + /* Ask privileged process what mechanisms it supports. */ + if (GSS_ERROR(PRIVSEP(gss_indicate_mechs(&min_status, &supported)))) + return; while (supported_mechs[i]->name != NULL) { if (GSS_ERROR(gss_test_oid_set_member(&min_status, @@ -98,6 +183,8 @@ ssh_gssapi_supported_oids(gss_OID_set *oidset) &supported_mechs[i]->oid, oidset); i++; } + + gss_release_oid_set(&min_status, &supported); } @@ -106,7 +193,7 @@ ssh_gssapi_supported_oids(gss_OID_set *oidset) * oid * credentials (from ssh_gssapi_acquire_cred) */ -/* Priviledged */ +/* Privileged */ OM_uint32 ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, gss_buffer_desc *send_tok, OM_uint32 *flags) @@ -154,11 +241,11 @@ ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, static OM_uint32 ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) { - char *tok; + u_char *tok; OM_uint32 offset; OM_uint32 oidl; - tok=ename->value; + tok = ename->value; #ifdef GSI /* GSI gss_export_name() is broken. */ if ((ctx->oid->length == gssapi_gsi_mech.oid.length) && @@ -176,7 +263,7 @@ ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) * header, and that the initial ID bytes are correct */ - if (ename->length<6 || memcmp(tok,"\x04\x01", 2)!=0) + if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0) return GSS_S_FAILURE; /* @@ -186,7 +273,7 @@ ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) * second without. */ - oidl = GET_16BIT(tok+2); /* length including next two bytes */ + oidl = get_u16(tok+2); /* length including next two bytes */ oidl = oidl-2; /* turn it into the _real_ length of the variable OID */ /* @@ -195,7 +282,7 @@ ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) */ if (tok[4] != 0x06 || tok[5] != oidl || ename->length < oidl+6 || - !ssh_gssapi_check_oid(ctx,tok+6,oidl)) + !ssh_gssapi_check_oid(ctx, tok+6, oidl)) return GSS_S_FAILURE; offset = oidl+6; @@ -203,14 +290,14 @@ ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) if (ename->length < offset+4) return GSS_S_FAILURE; - name->length = GET_32BIT(tok+offset); + name->length = get_u32(tok+offset); offset += 4; if (ename->length < offset+name->length) return GSS_S_FAILURE; name->value = xmalloc(name->length+1); - memcpy(name->value,tok+offset,name->length); + memcpy(name->value, tok+offset, name->length); ((char *)name->value)[name->length] = 0; return GSS_S_COMPLETE; @@ -219,13 +306,56 @@ ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) /* Extract the client details from a given context. This can only reliably * be called once for a context */ -/* Priviledged (called from accept_secure_ctx) */ +/* Privileged (called from accept_secure_ctx) */ OM_uint32 ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) { int i = 0; + int equal = 0; + gss_name_t new_name = GSS_C_NO_NAME; + gss_buffer_desc ename = GSS_C_EMPTY_BUFFER; + + if (options.gss_store_rekey && client->used && ctx->client_creds) { + if (client->mech->oid.length != ctx->oid->length || + (memcmp(client->mech->oid.elements, + ctx->oid->elements, ctx->oid->length) !=0)) { + debug("Rekeyed credentials have different mechanism"); + return GSS_S_COMPLETE; + } + + /* Call gss_inquire_cred rather than gss_inquire_cred_by_mech + because GSI doesn't support the latter. -jbasney */ + + if ((ctx->major = gss_inquire_cred(&ctx->minor, + ctx->client_creds, &new_name, + NULL, NULL, NULL))) { + ssh_gssapi_error(ctx); + return (ctx->major); + } + + ctx->major = gss_compare_name(&ctx->minor, client->name, + new_name, &equal); + + if (GSS_ERROR(ctx->major)) { + ssh_gssapi_error(ctx); + return (ctx->major); + } + + if (!equal) { + debug("Rekeyed credentials have different name"); + return GSS_S_COMPLETE; + } - gss_buffer_desc ename; + debug("Marking rekeyed credentials for export"); + + gss_release_name(&ctx->minor, &client->name); + gss_release_cred(&ctx->minor, &client->creds); + client->name = new_name; + client->creds = ctx->client_creds; + ctx->client_creds = GSS_C_NO_CREDENTIAL; + client->updated = 1; + return GSS_S_COMPLETE; + } client->mech = NULL; @@ -240,6 +370,16 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) if (client->mech == NULL) return GSS_S_FAILURE; + /* Call gss_inquire_cred rather than gss_inquire_cred_by_mech + because GSI doesn't support the latter. -jbasney */ + + if (ctx->client_creds && + (ctx->major = gss_inquire_cred(&ctx->minor, + ctx->client_creds, &client->name, NULL, NULL, NULL))) { + ssh_gssapi_error(ctx); + return (ctx->major); + } + if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, &client->displayname, NULL))) { ssh_gssapi_error(ctx); @@ -257,9 +397,15 @@ ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) return (ctx->major); } + gss_release_buffer(&ctx->minor, &ename); + /* We can't copy this structure, so we just move the pointer to it */ client->creds = ctx->client_creds; ctx->client_creds = GSS_C_NO_CREDENTIAL; + + /* needed for globus_gss_assist_map_and_authorize() */ + client->context = ctx->context; + return (ctx->major); } @@ -269,7 +415,8 @@ ssh_gssapi_cleanup_creds(void) { if (gssapi_client.store.filename != NULL) { /* Unlink probably isn't sufficient */ - debug("removing gssapi cred file\"%s\"", gssapi_client.store.filename); + debug("removing gssapi cred file\"%s\"", + gssapi_client.store.filename); unlink(gssapi_client.store.filename); } } @@ -279,6 +426,11 @@ void ssh_gssapi_storecreds(void) { if (gssapi_client.mech && gssapi_client.mech->storecreds) { + if (options.gss_creds_path) { + gssapi_client.store.filename = + expand_authorized_keys(options.gss_creds_path, + the_authctxt->pw); + } (*gssapi_client.mech->storecreds)(&gssapi_client); } else debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism"); @@ -294,141 +446,50 @@ ssh_gssapi_do_child(char ***envp, u_int *envsizep) if (gssapi_client.store.envvar != NULL && gssapi_client.store.envval != NULL) { - debug("Setting %s to %s", gssapi_client.store.envvar, - gssapi_client.store.envval); + gssapi_client.store.envval); child_set_env(envp, envsizep, gssapi_client.store.envvar, - gssapi_client.store.envval); + gssapi_client.store.envval); } } -/* Priviledged */ +/* Privileged */ int -ssh_gssapi_userok(char *user) +ssh_gssapi_userok(char *user, struct passwd *pw) { + OM_uint32 lmin; + if (gssapi_client.exportedname.length == 0 || gssapi_client.exportedname.value == NULL) { debug("No suitable client data"); return 0; } #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG - if (limited) { + if (limited && options.gsi_allow_limited_proxy != 1) { debug("limited proxy not acceptable for remote login"); return 0; } #endif if (gssapi_client.mech && gssapi_client.mech->userok) - return ((*gssapi_client.mech->userok)(&gssapi_client, user)); + if ((*gssapi_client.mech->userok)(&gssapi_client, user)) { + gssapi_client.used = 1; + gssapi_client.store.owner = pw; + return 1; + } else { + /* Destroy delegated credentials if userok fails */ + gss_release_buffer(&lmin, &gssapi_client.displayname); + gss_release_buffer(&lmin, &gssapi_client.exportedname); + gss_release_cred(&lmin, &gssapi_client.creds); + memset(&gssapi_client, 0, sizeof(ssh_gssapi_client)); + return 0; + } else debug("ssh_gssapi_userok: Unknown GSSAPI mechanism"); return (0); } -/* Return a list of the gss-group1-sha1-x mechanisms supported by this - * program. - * - * We only support the mechanisms that we've indicated in the list above, - * but we check that they're supported by the GSSAPI mechanism on the - * machine. We also check, before including them in the list, that - * we have the necesary information in order to carry out the key exchange - * (that is, that the user has credentials, the server's creds are accessible, - * etc) - * - * The way that this is done is fairly nasty, as we do a lot of work that - * is then thrown away. This should possibly be implemented with a cache - * that stores the results (in an expanded Gssctxt structure), which are - * then used by the first calls if that key exchange mechanism is chosen. - */ - -/* Unpriviledged */ -char * -ssh_gssapi_server_mechanisms() { - gss_OID_set supported; - Gssctxt *ctx = NULL; - OM_uint32 maj_status, min_status; - Buffer buf; - int i = 0; - int first = 0; - int present; - char * mechs; - - ssh_gssapi_supported_oids(&supported); - - buffer_init(&buf); - - while(supported_mechs[i]->name != NULL) { - if ((maj_status=gss_test_oid_set_member(&min_status, - &supported_mechs[i]->oid, - supported, - &present))) { - present=0; - } - - if (present) { - if (!GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, - &supported_mechs[i]->oid)))) { - /* Append gss_group1_sha1_x to our list */ - if (first++!=0) - buffer_put_char(&buf,','); - buffer_append(&buf, KEX_GSS_SHA1, - sizeof(KEX_GSS_SHA1)-1); - buffer_append(&buf, - supported_mechs[i]->enc_name, - strlen(supported_mechs[i]->enc_name)); - debug("GSSAPI mechanism %s (%s%s) supported", - supported_mechs[i]->name, KEX_GSS_SHA1, - supported_mechs[i]->enc_name); - } else { - debug("no credentials for GSSAPI mechanism %s", - supported_mechs[i]->name); - } - } else { - debug("GSSAPI mechanism %s not supported", - supported_mechs[i]->name); - } - ssh_gssapi_delete_ctx(&ctx); - i++; - } - - buffer_put_char(&buf,'\0'); - - mechs=xmalloc(buffer_len(&buf)); - buffer_get(&buf,mechs,buffer_len(&buf)); - buffer_free(&buf); - if (strlen(mechs)==0) { - options.gss_authentication = 0; /* no mechs. skip gss auth. */ - return(NULL); - } else { - return(mechs); - } -} - -/* Return the OID that corresponds to the given context name */ - -/* Unpriviledged */ -gss_OID -ssh_gssapi_server_id_kex(char *name) { - int i=0; - - if (strncmp(name, KEX_GSS_SHA1, sizeof(KEX_GSS_SHA1)-1) !=0) { - return(NULL); - } - - name+=sizeof(KEX_GSS_SHA1)-1; /* Move to the start of the MIME string */ - - while (supported_mechs[i]->name!=NULL && - strcmp(name,supported_mechs[i]->enc_name)!=0) { - i++; - } - - if (supported_mechs[i]->name==NULL) - return (NULL); - - debug("using GSSAPI mechanism %s (%s%s)", supported_mechs[i]->name, - KEX_GSS_SHA1, supported_mechs[i]->enc_name); - - return &supported_mechs[i]->oid; -} +/* ssh_gssapi_checkmic() moved to gss-genr.c so it can be called by + kexgss_client(). */ /* Priviledged */ int @@ -448,14 +509,90 @@ ssh_gssapi_localname(char **user) return(0); } -/* Priviledged */ -OM_uint32 -ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) +/* These bits are only used for rekeying. The unpriviledged child is running + * as the user, the monitor is root. + * + * In the child, we want to : + * *) Ask the monitor to store our credentials into the store we specify + * *) If it succeeds, maybe do a PAM update + */ + +/* Stuff for PAM */ + +#ifdef USE_PAM +static int ssh_gssapi_simple_conv(int n, const struct pam_message **msg, + struct pam_response **resp, void *data) { - ctx->major = gss_verify_mic(&ctx->minor, ctx->context, - gssbuf, gssmic, NULL); + return (PAM_CONV_ERR); +} +#endif - return (ctx->major); +void +ssh_gssapi_rekey_creds() { + int ok; +#ifdef USE_PAM + int ret; + pam_handle_t *pamh = NULL; + struct pam_conv pamconv = {ssh_gssapi_simple_conv, NULL}; + char *envstr; +#endif + + if (gssapi_client.store.filename == NULL && + gssapi_client.store.envval == NULL && + gssapi_client.store.envvar == NULL) + return; + + ok = PRIVSEP(ssh_gssapi_update_creds(&gssapi_client.store)); + + if (!ok) + return; + + debug("Rekeyed credentials stored successfully"); + + /* Actually managing to play with the ssh pam stack from here will + * be next to impossible. In any case, we may want different options + * for rekeying. So, use our own :) + */ +#ifdef USE_PAM + if (!use_privsep) { + debug("Not even going to try and do PAM with privsep disabled"); + return; + } + + ret = pam_start("sshd-rekey", gssapi_client.store.owner->pw_name, + &pamconv, &pamh); + if (ret) + return; + + xasprintf(&envstr, "%s=%s", gssapi_client.store.envvar, + gssapi_client.store.envval); + + ret = pam_putenv(pamh, envstr); + if (!ret) + pam_setcred(pamh, PAM_REINITIALIZE_CRED); + pam_end(pamh, PAM_SUCCESS); +#endif +} + +int +ssh_gssapi_update_creds(ssh_gssapi_ccache *store) { + int ok = 0; + + /* Check we've got credentials to store */ + if (!gssapi_client.updated) + return 0; + + gssapi_client.updated = 0; + + temporarily_use_uid(gssapi_client.store.owner); + if (gssapi_client.mech && gssapi_client.mech->updatecreds) + ok = (*gssapi_client.mech->updatecreds)(store, &gssapi_client); + else + debug("No update function for this mechanism"); + + restore_uid(); + + return ok; } #endif