/* * Copyright (c) 1999-2005, 2007-2008 Todd C. Miller * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * 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. * * Sponsored in part by the Defense Advanced Research Projects * Agency (DARPA) and Air Force Research Laboratory, Air Force * Materiel Command, USAF, under agreement number F39502-99-1-0512. */ #include #include #include #include #ifdef STDC_HEADERS # include # include #else # ifdef HAVE_STDLIB_H # include # endif #endif /* STDC_HEADERS */ #ifdef HAVE_STRING_H # include #else # ifdef HAVE_STRINGS_H # include # endif #endif /* HAVE_STRING_H */ #ifdef HAVE_UNISTD_H # include #endif /* HAVE_UNISTD_H */ #include #include #ifdef HAVE_HEIMDAL #include #endif #include "sudo.h" #include "sudo_auth.h" #ifndef lint __unused static const char rcsid[] = "$Sudo: kerb5.c,v 1.36 2008/11/09 14:13:13 millert Exp $"; #endif /* lint */ #ifdef HAVE_HEIMDAL # define extract_name(c, p) krb5_principal_get_comp_string(c, p, 1) # define krb5_free_data_contents(c, d) krb5_data_free(d) #else # define extract_name(c, p) (krb5_princ_component(c, p, 1)->data) #endif #ifndef HAVE_KRB5_VERIFY_USER static int verify_krb_v5_tgt __P((krb5_context, krb5_creds *, char *)); #endif static struct _sudo_krb5_data { krb5_context sudo_context; krb5_principal princ; krb5_ccache ccache; } sudo_krb5_data = { NULL, NULL, NULL }; typedef struct _sudo_krb5_data *sudo_krb5_datap; #ifndef HAVE_KRB5_GET_INIT_CREDS_OPT_ALLOC static krb5_error_code krb5_get_init_creds_opt_alloc(context, opts) krb5_context context; krb5_get_init_creds_opt **opts; { *opts = emalloc(sizeof(krb5_get_init_creds_opt)); return 0; } static void krb5_get_init_creds_opt_free(opts) krb5_get_init_creds_opt *opts; { free(opts); } #endif int kerb5_init(pw, promptp, auth) struct passwd *pw; char **promptp; sudo_auth *auth; { krb5_context sudo_context; krb5_ccache ccache; krb5_principal princ; krb5_error_code error; char cache_name[64]; char *pname; auth->data = (void *) &sudo_krb5_data; /* Stash all our data here */ #ifdef HAVE_KRB5_INIT_SECURE_CONTEXT error = krb5_init_secure_context(&(sudo_krb5_data.sudo_context)); #else error = krb5_init_context(&(sudo_krb5_data.sudo_context)); #endif if (error) return(AUTH_FAILURE); sudo_context = sudo_krb5_data.sudo_context; if ((error = krb5_parse_name(sudo_context, pw->pw_name, &(sudo_krb5_data.princ)))) { log_error(NO_EXIT|NO_MAIL, "%s: unable to parse '%s': %s", auth->name, pw->pw_name, error_message(error)); return(AUTH_FAILURE); } princ = sudo_krb5_data.princ; /* * Really, we need to tell the caller not to prompt for password. * The API does not currently provide this unless the auth is standalone. */ #if 1 if ((error = krb5_unparse_name(sudo_context, princ, &pname))) { log_error(NO_EXIT|NO_MAIL, "%s: unable to unparse princ ('%s'): %s", auth->name, pw->pw_name, error_message(error)); return(AUTH_FAILURE); } /* Only rewrite prompt if user didn't specify their own. */ /*if (!strcmp(prompt, PASSPROMPT)) { */ easprintf(promptp, "Password for %s: ", pname); /*}*/ free(pname); #endif (void) snprintf(cache_name, sizeof(cache_name), "MEMORY:sudocc_%ld", (long) getpid()); if ((error = krb5_cc_resolve(sudo_context, cache_name, &(sudo_krb5_data.ccache)))) { log_error(NO_EXIT|NO_MAIL, "%s: unable to resolve ccache: %s", auth->name, error_message(error)); return(AUTH_FAILURE); } ccache = sudo_krb5_data.ccache; return(AUTH_SUCCESS); } #ifdef HAVE_KRB5_VERIFY_USER int kerb5_verify(pw, pass, auth) struct passwd *pw; char *pass; sudo_auth *auth; { krb5_context sudo_context; krb5_principal princ; krb5_ccache ccache; krb5_error_code error; sudo_context = ((sudo_krb5_datap) auth->data)->sudo_context; princ = ((sudo_krb5_datap) auth->data)->princ; ccache = ((sudo_krb5_datap) auth->data)->ccache; error = krb5_verify_user(sudo_context, princ, ccache, pass, 1, NULL); return (error ? AUTH_FAILURE : AUTH_SUCCESS); } #else int kerb5_verify(pw, pass, auth) struct passwd *pw; char *pass; sudo_auth *auth; { krb5_context sudo_context; krb5_principal princ; krb5_creds credbuf, *creds = NULL; krb5_ccache ccache; krb5_error_code error; krb5_get_init_creds_opt *opts = NULL; sudo_context = ((sudo_krb5_datap) auth->data)->sudo_context; princ = ((sudo_krb5_datap) auth->data)->princ; ccache = ((sudo_krb5_datap) auth->data)->ccache; /* Set default flags based on the local config file. */ error = krb5_get_init_creds_opt_alloc(sudo_context, &opts); if (error) { log_error(NO_EXIT|NO_MAIL, "%s: unable to allocate options: %s", auth->name, error_message(error)); goto done; } #ifdef HAVE_HEIMDAL krb5_get_init_creds_opt_set_default_flags(sudo_context, NULL, krb5_principal_get_realm(sudo_context, princ), opts); #endif /* Note that we always obtain a new TGT to verify the user */ if ((error = krb5_get_init_creds_password(sudo_context, &credbuf, princ, pass, krb5_prompter_posix, NULL, 0, NULL, opts))) { /* Don't print error if just a bad password */ if (error != KRB5KRB_AP_ERR_BAD_INTEGRITY) log_error(NO_EXIT|NO_MAIL, "%s: unable to get credentials: %s", auth->name, error_message(error)); goto done; } creds = &credbuf; /* Verify the TGT to prevent spoof attacks. */ if ((error = verify_krb_v5_tgt(sudo_context, creds, auth->name))) goto done; /* Store cred in cred cache. */ if ((error = krb5_cc_initialize(sudo_context, ccache, princ))) { log_error(NO_EXIT|NO_MAIL, "%s: unable to initialize ccache: %s", auth->name, error_message(error)); } else if ((error = krb5_cc_store_cred(sudo_context, ccache, creds))) { log_error(NO_EXIT|NO_MAIL, "%s: unable to store cred in ccache: %s", auth->name, error_message(error)); } done: if (opts) { #ifdef HAVE_KRB5_GET_INIT_CREDS_OPT_FREE_TWO_ARGS krb5_get_init_creds_opt_free(sudo_context, opts); #else krb5_get_init_creds_opt_free(opts); #endif } if (creds) krb5_free_cred_contents(sudo_context, creds); return (error ? AUTH_FAILURE : AUTH_SUCCESS); } #endif int kerb5_cleanup(pw, auth) struct passwd *pw; sudo_auth *auth; { krb5_context sudo_context; krb5_principal princ; krb5_ccache ccache; sudo_context = ((sudo_krb5_datap) auth->data)->sudo_context; princ = ((sudo_krb5_datap) auth->data)->princ; ccache = ((sudo_krb5_datap) auth->data)->ccache; if (sudo_context) { if (ccache) krb5_cc_destroy(sudo_context, ccache); if (princ) krb5_free_principal(sudo_context, princ); krb5_free_context(sudo_context); } return(AUTH_SUCCESS); } #ifndef HAVE_KRB5_VERIFY_USER /* * Verify the Kerberos ticket-granting ticket just retrieved for the * user. If the Kerberos server doesn't respond, assume the user is * trying to fake us out (since we DID just get a TGT from what is * supposedly our KDC). * * Returns 0 for successful authentication, non-zero for failure. */ static int verify_krb_v5_tgt(sudo_context, cred, auth_name) krb5_context sudo_context; krb5_creds *cred; char *auth_name; /* For error reporting */ { krb5_error_code error; krb5_principal server; krb5_verify_init_creds_opt vopt; /* * Get the server principal for the local host. * (Use defaults of "host" and canonicalized local name.) */ if ((error = krb5_sname_to_principal(sudo_context, NULL, NULL, KRB5_NT_SRV_HST, &server))) { log_error(NO_EXIT|NO_MAIL, "%s: unable to get host principal: %s", auth_name, error_message(error)); return(-1); } /* Initialize verify opts and set secure mode */ krb5_verify_init_creds_opt_init(&vopt); krb5_verify_init_creds_opt_set_ap_req_nofail(&vopt, 1); /* verify the Kerberos ticket-granting ticket we just retrieved */ error = krb5_verify_init_creds(sudo_context, cred, server, NULL, NULL, &vopt); krb5_free_principal(sudo_context, server); if (error) log_error(NO_EXIT|NO_MAIL, "%s: Cannot verify TGT! Possible attack!: %s", auth_name, error_message(error)); return(error); } #endif