/* $NetBSD: transited.c,v 1.2.22.1 2023/08/11 13:40:01 martin Exp $ */ /* * Copyright (c) 1997 - 2001, 2003 Kungliga Tekniska Högskolan * (Royal Institute of Technology, Stockholm, Sweden). * 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. * * 3. Neither the name of the Institute nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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 INSTITUTE OR CONTRIBUTORS 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 "krb5_locl.h" /* this is an attempt at one of the most horrible `compression' schemes that has ever been invented; it's so amazingly brain-dead that words can not describe it, and all this just to save a few silly bytes */ struct tr_realm { char *realm; unsigned leading_space:1; unsigned leading_slash:1; unsigned trailing_dot:1; struct tr_realm *next; }; static void free_realms(struct tr_realm *r) { struct tr_realm *p; while(r){ p = r; r = r->next; free(p->realm); free(p); } } static int make_path(krb5_context context, struct tr_realm *r, const char *from, const char *to) { struct tr_realm *tmp; const char *p; if(strlen(from) < strlen(to)){ const char *str; str = from; from = to; to = str; } if(strcmp(from + strlen(from) - strlen(to), to) == 0){ p = from; while(1){ p = strchr(p, '.'); if(p == NULL) { krb5_clear_error_message (context); return KRB5KDC_ERR_POLICY; } p++; if(strcmp(p, to) == 0) break; tmp = calloc(1, sizeof(*tmp)); if(tmp == NULL) return krb5_enomem(context); tmp->next = r->next; r->next = tmp; tmp->realm = strdup(p); if(tmp->realm == NULL){ r->next = tmp->next; free(tmp); return krb5_enomem(context); } } }else if(strncmp(from, to, strlen(to)) == 0){ p = from + strlen(from); while(1){ while(p >= from && *p != '/') p--; if(p == from) return KRB5KDC_ERR_POLICY; if(strncmp(to, from, p - from) == 0) break; tmp = calloc(1, sizeof(*tmp)); if(tmp == NULL) return krb5_enomem(context); tmp->next = r->next; r->next = tmp; tmp->realm = malloc(p - from + 1); if(tmp->realm == NULL){ r->next = tmp->next; free(tmp); return krb5_enomem(context); } memcpy(tmp->realm, from, p - from); tmp->realm[p - from] = '\0'; p--; } } else { krb5_clear_error_message (context); return KRB5KDC_ERR_POLICY; } return 0; } static int make_paths(krb5_context context, struct tr_realm *realms, const char *client_realm, const char *server_realm) { struct tr_realm *r; int ret; const char *prev_realm = client_realm; const char *next_realm = NULL; for(r = realms; r; r = r->next){ /* it *might* be that you can have more than one empty component in a row, at least that's how I interpret the "," exception in 1510 */ if(r->realm[0] == '\0'){ while(r->next && r->next->realm[0] == '\0') r = r->next; if(r->next) next_realm = r->next->realm; else next_realm = server_realm; ret = make_path(context, r, prev_realm, next_realm); if(ret){ free_realms(realms); return ret; } } prev_realm = r->realm; } return 0; } static int expand_realms(krb5_context context, struct tr_realm *realms, const char *client_realm) { struct tr_realm *r; const char *prev_realm = NULL; for(r = realms; r; r = r->next){ if(r->trailing_dot){ char *tmp; size_t len; if(prev_realm == NULL) prev_realm = client_realm; len = strlen(r->realm) + strlen(prev_realm) + 1; tmp = realloc(r->realm, len); if(tmp == NULL){ free_realms(realms); return krb5_enomem(context); } r->realm = tmp; strlcat(r->realm, prev_realm, len); }else if(r->leading_slash && !r->leading_space && prev_realm){ /* yet another exception: if you use x500-names, the leading realm doesn't have to be "quoted" with a space */ char *tmp; size_t len = strlen(r->realm) + strlen(prev_realm) + 1; tmp = malloc(len); if(tmp == NULL){ free_realms(realms); return krb5_enomem(context); } strlcpy(tmp, prev_realm, len); strlcat(tmp, r->realm, len); free(r->realm); r->realm = tmp; } prev_realm = r->realm; } return 0; } static struct tr_realm * make_realm(char *realm) { struct tr_realm *r; char *p, *q; int quote = 0; r = calloc(1, sizeof(*r)); if(r == NULL){ free(realm); return NULL; } r->realm = realm; for(p = q = r->realm; *p; p++){ if(p == r->realm && *p == ' '){ r->leading_space = 1; continue; } if(q == r->realm && *p == '/') r->leading_slash = 1; if(quote){ *q++ = *p; quote = 0; continue; } if(*p == '\\'){ quote = 1; continue; } if(p[0] == '.' && p[1] == '\0') r->trailing_dot = 1; *q++ = *p; } *q = '\0'; return r; } static struct tr_realm* append_realm(struct tr_realm *head, struct tr_realm *r) { struct tr_realm *p; if(head == NULL){ r->next = NULL; return r; } p = head; while(p->next) p = p->next; p->next = r; return head; } static int decode_realms(krb5_context context, const char *tr, int length, struct tr_realm **realms) { struct tr_realm *r = NULL; char *tmp; int quote = 0; const char *start = tr; int i; for(i = 0; i < length; i++){ if(quote){ quote = 0; continue; } if(tr[i] == '\\'){ quote = 1; continue; } if(tr[i] == ','){ tmp = malloc(tr + i - start + 1); if(tmp == NULL) return krb5_enomem(context); memcpy(tmp, start, tr + i - start); tmp[tr + i - start] = '\0'; r = make_realm(tmp); if(r == NULL){ free_realms(*realms); *realms = NULL; return krb5_enomem(context); } *realms = append_realm(*realms, r); start = tr + i + 1; } } tmp = malloc(tr + i - start + 1); if(tmp == NULL){ free_realms(*realms); *realms = NULL; return krb5_enomem(context); } memcpy(tmp, start, tr + i - start); tmp[tr + i - start] = '\0'; r = make_realm(tmp); if(r == NULL){ free_realms(*realms); *realms = NULL; return krb5_enomem(context); } *realms = append_realm(*realms, r); return 0; } KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL krb5_domain_x500_decode(krb5_context context, krb5_data tr, char ***realms, unsigned int *num_realms, const char *client_realm, const char *server_realm) { struct tr_realm *r = NULL; struct tr_realm *p, **q; int ret; if(tr.length == 0) { *realms = NULL; *num_realms = 0; return 0; } /* split string in components */ ret = decode_realms(context, tr.data, tr.length, &r); if(ret) return ret; /* apply prefix rule */ ret = expand_realms(context, r, client_realm); if(ret) return ret; ret = make_paths(context, r, client_realm, server_realm); if(ret) return ret; /* remove empty components and count realms */ *num_realms = 0; for(q = &r; *q; ){ if((*q)->realm[0] == '\0'){ p = *q; *q = (*q)->next; free(p->realm); free(p); }else{ q = &(*q)->next; (*num_realms)++; } } if (*num_realms + 1 > UINT_MAX/sizeof(**realms)) return ERANGE; { char **R; R = malloc((*num_realms + 1) * sizeof(*R)); if (R == NULL) return krb5_enomem(context); *realms = R; while(r){ *R++ = r->realm; p = r->next; free(r); r = p; } } return 0; } KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL krb5_domain_x500_encode(char **realms, unsigned int num_realms, krb5_data *encoding) { char *s = NULL; int len = 0; unsigned int i; krb5_data_zero(encoding); if (num_realms == 0) return 0; for(i = 0; i < num_realms; i++){ len += strlen(realms[i]); if(realms[i][0] == '/') len++; } len += num_realms - 1; s = malloc(len + 1); if (s == NULL) return ENOMEM; *s = '\0'; for(i = 0; i < num_realms; i++){ if(i) strlcat(s, ",", len + 1); if(realms[i][0] == '/') strlcat(s, " ", len + 1); strlcat(s, realms[i], len + 1); } encoding->data = s; encoding->length = strlen(s); return 0; } KRB5_LIB_FUNCTION void KRB5_LIB_CALL _krb5_free_capath(krb5_context context, char **capath) { char **s; for (s = capath; s && *s; ++s) free(*s); free(capath); } struct hier_iter { const char *local_realm; const char *server_realm; const char *lr; /* Pointer into tail of local realm */ const char *sr; /* Pointer into tail of server realm */ size_t llen; /* Length of local_realm */ size_t slen; /* Length of server_realm */ size_t len; /* Length of common suffix */ size_t num; /* Path element count */ }; /* * Step up from local_realm to common suffix, or else down to server_realm. */ static const char * hier_next(struct hier_iter *state) { const char *lr = state->lr; const char *sr = state->sr; const char *lsuffix = state->local_realm + state->llen - state->len; const char *server_realm = state->server_realm; if (lr != NULL) { while (lr < lsuffix) if (*lr++ == '.') return state->lr = lr; state->lr = NULL; } if (sr != NULL) { while (--sr >= server_realm) if (sr == server_realm || sr[-1] == '.') return state->sr = sr; state->sr = NULL; } return NULL; } static void hier_init(struct hier_iter *state, const char *local_realm, const char *server_realm) { size_t llen; size_t slen; size_t len = 0; const char *lr; const char *sr; state->local_realm = local_realm; state->server_realm = server_realm; state->llen = llen = strlen(local_realm); state->slen = slen = strlen(server_realm); state->len = 0; state->num = 0; if (slen == 0 || llen == 0) return; /* Find first difference from the back */ for (lr = local_realm + llen, sr = server_realm + slen; lr != local_realm && sr != server_realm; --lr, --sr) { if (lr[-1] != sr[-1]) break; if (lr[-1] == '.') len = llen - (lr - local_realm); } /* Nothing in common? */ if (*lr == '\0') return; /* Everything in common? */ if (llen == slen && lr == local_realm) return; /* Is one realm is a suffix of the other? */ if ((llen < slen && lr == local_realm && sr[-1] == '.') || (llen > slen && sr == server_realm && lr[-1] == '.')) len = llen - (lr - local_realm); state->len = len; /* `lr` starts at local realm and walks up the tree to common suffix */ state->lr = local_realm; /* `sr` starts at common suffix in server realm and walks down the tree */ state->sr = server_realm + slen - len; /* Count elements and reset */ while (hier_next(state) != NULL) ++state->num; state->lr = local_realm; state->sr = server_realm + slen - len; } /* * Find a referral path from client_realm to server_realm via local_realm. * Either via [capaths] or hierarchicaly. */ KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL _krb5_find_capath(krb5_context context, const char *client_realm, const char *local_realm, const char *server_realm, krb5_boolean use_hierarchical, char ***rpath, size_t *npath) { char **confpath; char **capath; struct hier_iter hier_state; char **rp; const char *r; *rpath = NULL; *npath = 0; confpath = krb5_config_get_strings(context, NULL, "capaths", client_realm, server_realm, NULL); if (confpath == NULL) confpath = krb5_config_get_strings(context, NULL, "capaths", local_realm, server_realm, NULL); /* * With a [capaths] setting from the client to the server we look for our * own realm in the list. If our own realm is not present, we return the * full list. Otherwise, we return our realm's successors, or possibly * NULL. Ignoring a [capaths] settings risks loops plus would violate * explicit policy and the principle of least surpise. */ if (confpath != NULL) { char **start = confpath; size_t i; size_t n; for (rp = start; *rp; rp++) if (strcmp(*rp, local_realm) == 0) start = rp+1; n = rp - start; if (n == 0) { krb5_config_free_strings(confpath); return 0; } capath = calloc(n + 1, sizeof(*capath)); if (capath == NULL) { krb5_config_free_strings(confpath); return krb5_enomem(context); } for (i = 0, rp = start; *rp; rp++) { if ((capath[i++] = strdup(*rp)) == NULL) { _krb5_free_capath(context, capath); krb5_config_free_strings(confpath); return krb5_enomem(context); } } krb5_config_free_strings(confpath); capath[i] = NULL; *rpath = capath; *npath = n; return 0; } /* The use_hierarchical flag makes hierarchical path lookup unconditional */ if (! use_hierarchical && ! krb5_config_get_bool_default(context, NULL, TRUE, "libdefaults", "allow_hierarchical_capaths", NULL)) return 0; /* * When validating transit paths, local_realm == client_realm. Otherwise, * with hierarchical referrals, they may differ, and we may be building a * path forward from our own realm! */ hier_init(&hier_state, local_realm, server_realm); if (hier_state.num == 0) return 0; rp = capath = calloc(hier_state.num + 1, sizeof(*capath)); if (capath == NULL) return krb5_enomem(context); while ((r = hier_next(&hier_state)) != NULL) { if ((*rp++ = strdup(r)) == NULL) { _krb5_free_capath(context, capath); return krb5_enomem(context); } } *rp = NULL; *rpath = capath; *npath = hier_state.num; return 0; } KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL krb5_check_transited(krb5_context context, krb5_const_realm client_realm, krb5_const_realm server_realm, krb5_realm *realms, unsigned int num_realms, int *bad_realm) { krb5_error_code ret = 0; char **capath = NULL; size_t num_capath = 0; size_t i = 0; size_t j = 0; /* In transit checks hierarchical capaths are optional */ ret = _krb5_find_capath(context, client_realm, client_realm, server_realm, FALSE, &capath, &num_capath); if (ret) return ret; for (i = 0; i < num_realms; i++) { for (j = 0; j < num_capath; ++j) { if (strcmp(realms[i], capath[j]) == 0) break; } if (j == num_capath) { _krb5_free_capath(context, capath); krb5_set_error_message (context, KRB5KRB_AP_ERR_ILL_CR_TKT, N_("no transit allowed " "through realm %s from %s to %s", ""), realms[i], client_realm, server_realm); if (bad_realm) *bad_realm = i; return KRB5KRB_AP_ERR_ILL_CR_TKT; } } _krb5_free_capath(context, capath); return 0; } KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL krb5_check_transited_realms(krb5_context context, const char *const *realms, unsigned int num_realms, int *bad_realm) { size_t i; int ret = 0; char **bad_realms = krb5_config_get_strings(context, NULL, "libdefaults", "transited_realms_reject", NULL); if(bad_realms == NULL) return 0; for(i = 0; i < num_realms; i++) { char **p; for(p = bad_realms; *p; p++) if(strcmp(*p, realms[i]) == 0) { ret = KRB5KRB_AP_ERR_ILL_CR_TKT; krb5_set_error_message (context, ret, N_("no transit allowed " "through realm %s", ""), *p); if(bad_realm) *bad_realm = i; break; } } krb5_config_free_strings(bad_realms); return ret; } #if 0 int main(int argc, char **argv) { krb5_data x; char **r; int num, i; x.data = argv[1]; x.length = strlen(x.data); if(domain_expand(x, &r, &num, argv[2], argv[3])) exit(1); for(i = 0; i < num; i++) printf("%s\n", r[i]); return 0; } #endif