| /* $OpenBSD: gss-serv.c,v 1.25 2014/02/02 03:44:31 djm Exp $ */ |
| |
| /* |
| * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "includes.h" |
| |
| #ifdef GSSAPI |
| |
| #include <sys/types.h> |
| #include <sys/param.h> |
| |
| #include <stdarg.h> |
| #include <string.h> |
| #include <unistd.h> |
| |
| #include "openbsd-compat/sys-queue.h" |
| #include "xmalloc.h" |
| #include "buffer.h" |
| #include "key.h" |
| #include "hostfile.h" |
| #include "auth.h" |
| #include "log.h" |
| #include "channels.h" |
| #include "session.h" |
| #include "misc.h" |
| |
| #include "ssh-gss.h" |
| |
| static ssh_gssapi_client gssapi_client = |
| { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, |
| GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL, NULL}}; |
| |
| ssh_gssapi_mech gssapi_null_mech = |
| { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; |
| |
| #ifdef KRB5 |
| extern ssh_gssapi_mech gssapi_kerberos_mech; |
| #endif |
| |
| ssh_gssapi_mech* supported_mechs[]= { |
| #ifdef KRB5 |
| &gssapi_kerberos_mech, |
| #endif |
| &gssapi_null_mech, |
| }; |
| |
| |
| /* |
| * 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; |
| |
| 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); |
| } |
| |
| /* 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 */ |
| void |
| ssh_gssapi_supported_oids(gss_OID_set *oidset) |
| { |
| int i = 0; |
| OM_uint32 min_status; |
| int present; |
| gss_OID_set supported; |
| |
| gss_create_empty_oid_set(&min_status, oidset); |
| gss_indicate_mechs(&min_status, &supported); |
| |
| while (supported_mechs[i]->name != NULL) { |
| if (GSS_ERROR(gss_test_oid_set_member(&min_status, |
| &supported_mechs[i]->oid, supported, &present))) |
| present = 0; |
| if (present) |
| gss_add_oid_set_member(&min_status, |
| &supported_mechs[i]->oid, oidset); |
| i++; |
| } |
| |
| gss_release_oid_set(&min_status, &supported); |
| } |
| |
| |
| /* Wrapper around accept_sec_context |
| * Requires that the context contains: |
| * oid |
| * credentials (from ssh_gssapi_acquire_cred) |
| */ |
| /* Privileged */ |
| OM_uint32 |
| ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, |
| gss_buffer_desc *send_tok, OM_uint32 *flags) |
| { |
| OM_uint32 status; |
| gss_OID mech; |
| |
| ctx->major = gss_accept_sec_context(&ctx->minor, |
| &ctx->context, ctx->creds, recv_tok, |
| GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech, |
| send_tok, flags, NULL, &ctx->client_creds); |
| |
| if (GSS_ERROR(ctx->major)) |
| ssh_gssapi_error(ctx); |
| |
| if (ctx->client_creds) |
| debug("Received some client credentials"); |
| else |
| debug("Got no client credentials"); |
| |
| status = ctx->major; |
| |
| /* Now, if we're complete and we have the right flags, then |
| * we flag the user as also having been authenticated |
| */ |
| |
| if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) && |
| (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) { |
| if (ssh_gssapi_getclient(ctx, &gssapi_client)) |
| fatal("Couldn't convert client name"); |
| } |
| |
| return (status); |
| } |
| |
| /* |
| * This parses an exported name, extracting the mechanism specific portion |
| * to use for ACL checking. It verifies that the name belongs the mechanism |
| * originally selected. |
| */ |
| static OM_uint32 |
| ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) |
| { |
| u_char *tok; |
| OM_uint32 offset; |
| OM_uint32 oidl; |
| |
| tok = ename->value; |
| |
| /* |
| * Check that ename is long enough for all of the fixed length |
| * header, and that the initial ID bytes are correct |
| */ |
| |
| if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0) |
| return GSS_S_FAILURE; |
| |
| /* |
| * Extract the OID, and check it. Here GSSAPI breaks with tradition |
| * and does use the OID type and length bytes. To confuse things |
| * there are two lengths - the first including these, and the |
| * second without. |
| */ |
| |
| oidl = get_u16(tok+2); /* length including next two bytes */ |
| oidl = oidl-2; /* turn it into the _real_ length of the variable OID */ |
| |
| /* |
| * Check the BER encoding for correct type and length, that the |
| * string is long enough and that the OID matches that in our context |
| */ |
| if (tok[4] != 0x06 || tok[5] != oidl || |
| ename->length < oidl+6 || |
| !ssh_gssapi_check_oid(ctx, tok+6, oidl)) |
| return GSS_S_FAILURE; |
| |
| offset = oidl+6; |
| |
| if (ename->length < offset+4) |
| return GSS_S_FAILURE; |
| |
| name->length = get_u32(tok+offset); |
| offset += 4; |
| |
| if (UINT_MAX - offset < name->length) |
| return GSS_S_FAILURE; |
| if (ename->length < offset+name->length) |
| return GSS_S_FAILURE; |
| |
| name->value = xmalloc(name->length+1); |
| memcpy(name->value, tok+offset, name->length); |
| ((char *)name->value)[name->length] = 0; |
| |
| return GSS_S_COMPLETE; |
| } |
| |
| /* Extract the client details from a given context. This can only reliably |
| * be called once for a context */ |
| |
| /* Privileged (called from accept_secure_ctx) */ |
| OM_uint32 |
| ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) |
| { |
| int i = 0; |
| |
| gss_buffer_desc ename; |
| |
| client->mech = NULL; |
| |
| while (supported_mechs[i]->name != NULL) { |
| if (supported_mechs[i]->oid.length == ctx->oid->length && |
| (memcmp(supported_mechs[i]->oid.elements, |
| ctx->oid->elements, ctx->oid->length) == 0)) |
| client->mech = supported_mechs[i]; |
| i++; |
| } |
| |
| if (client->mech == NULL) |
| return GSS_S_FAILURE; |
| |
| if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, |
| &client->displayname, NULL))) { |
| ssh_gssapi_error(ctx); |
| return (ctx->major); |
| } |
| |
| if ((ctx->major = gss_export_name(&ctx->minor, ctx->client, |
| &ename))) { |
| ssh_gssapi_error(ctx); |
| return (ctx->major); |
| } |
| |
| if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename, |
| &client->exportedname))) { |
| return (ctx->major); |
| } |
| |
| /* 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; |
| return (ctx->major); |
| } |
| |
| /* As user - called on fatal/exit */ |
| void |
| 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); |
| unlink(gssapi_client.store.filename); |
| } |
| } |
| |
| /* As user */ |
| void |
| ssh_gssapi_storecreds(void) |
| { |
| if (gssapi_client.mech && gssapi_client.mech->storecreds) { |
| (*gssapi_client.mech->storecreds)(&gssapi_client); |
| } else |
| debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism"); |
| } |
| |
| /* This allows GSSAPI methods to do things to the childs environment based |
| * on the passed authentication process and credentials. |
| */ |
| /* As user */ |
| void |
| 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); |
| child_set_env(envp, envsizep, gssapi_client.store.envvar, |
| gssapi_client.store.envval); |
| } |
| } |
| |
| /* Privileged */ |
| int |
| ssh_gssapi_userok(char *user) |
| { |
| OM_uint32 lmin; |
| |
| if (gssapi_client.exportedname.length == 0 || |
| gssapi_client.exportedname.value == NULL) { |
| debug("No suitable client data"); |
| return 0; |
| } |
| if (gssapi_client.mech && gssapi_client.mech->userok) |
| if ((*gssapi_client.mech->userok)(&gssapi_client, user)) |
| 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); |
| explicit_bzero(&gssapi_client, |
| sizeof(ssh_gssapi_client)); |
| return 0; |
| } |
| else |
| debug("ssh_gssapi_userok: Unknown GSSAPI mechanism"); |
| return (0); |
| } |
| |
| /* Privileged */ |
| OM_uint32 |
| ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) |
| { |
| ctx->major = gss_verify_mic(&ctx->minor, ctx->context, |
| gssbuf, gssmic, NULL); |
| |
| return (ctx->major); |
| } |
| |
| #endif |