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home:dirkmueller:acdc:as_python3_module
libunbound-devel-mini.15546
patch_cve_2019-18934.patch
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File patch_cve_2019-18934.patch of Package libunbound-devel-mini.15546
diff --git a/ipsecmod/ipsecmod.c b/ipsecmod/ipsecmod.c index c8400c6..9e916d6 100644 --- a/ipsecmod/ipsecmod.c +++ b/ipsecmod/ipsecmod.c @@ -162,6 +162,71 @@ generate_request(struct module_qstate* qstate, int id, uint8_t* name, } /** + * Check if the string passed is a valid domain name with safe characters to + * pass to a shell. + * This will only allow: + * - digits + * - alphas + * - hyphen (not at the start) + * - dot (not at the start, or the only character) + * - underscore + * @param s: pointer to the string. + * @param slen: string's length. + * @return true if s only contains safe characters; false otherwise. + */ +static int +domainname_has_safe_characters(char* s, size_t slen) { + size_t i; + for(i = 0; i < slen; i++) { + if(s[i] == '\0') return 1; + if((s[i] == '-' && i != 0) + || (s[i] == '.' && (i != 0 || s[1] == '\0')) + || (s[i] == '_') || (s[i] >= '0' && s[i] <= '9') + || (s[i] >= 'A' && s[i] <= 'Z') + || (s[i] >= 'a' && s[i] <= 'z')) { + continue; + } + return 0; + } + return 1; +} + +/** + * Check if the stringified IPSECKEY RDATA contains safe characters to pass to + * a shell. + * This is only relevant for checking the gateway when the gateway type is 3 + * (domainname). + * @param s: pointer to the string. + * @param slen: string's length. + * @return true if s contains only safe characters; false otherwise. + */ +static int +ipseckey_has_safe_characters(char* s, size_t slen) { + int precedence, gateway_type, algorithm; + char* gateway; + gateway = (char*)calloc(slen, sizeof(char)); + if(!gateway) { + log_err("ipsecmod: out of memory when calling the hook"); + return 0; + } + if(sscanf(s, "%d %d %d %s ", + &precedence, &gateway_type, &algorithm, gateway) != 4) { + free(gateway); + return 0; + } + if(gateway_type != 3) { + free(gateway); + return 1; + } + if(domainname_has_safe_characters(gateway, slen)) { + free(gateway); + return 1; + } + free(gateway); + return 0; +} + +/** * Prepare the data and call the hook. * * @param qstate: query state. @@ -175,7 +240,7 @@ call_hook(struct module_qstate* qstate, struct ipsecmod_qstate* iq, { size_t slen, tempdata_len, tempstring_len, i; char str[65535], *s, *tempstring; - int w; + int w = 0, w_temp, qtype; struct ub_packed_rrset_key* rrset_key; struct packed_rrset_data* rrset_data; uint8_t *tempdata; @@ -192,9 +257,9 @@ call_hook(struct module_qstate* qstate, struct ipsecmod_qstate* iq, memset(s, 0, slen); /* Copy the hook into the buffer. */ - sldns_str_print(&s, &slen, "%s", qstate->env->cfg->ipsecmod_hook); + w += sldns_str_print(&s, &slen, "%s", qstate->env->cfg->ipsecmod_hook); /* Put space into the buffer. */ - sldns_str_print(&s, &slen, " "); + w += sldns_str_print(&s, &slen, " "); /* Copy the qname into the buffer. */ tempstring = sldns_wire2str_dname(qstate->qinfo.qname, qstate->qinfo.qname_len); @@ -202,68 +267,96 @@ call_hook(struct module_qstate* qstate, struct ipsecmod_qstate* iq, log_err("ipsecmod: out of memory when calling the hook"); return 0; } - sldns_str_print(&s, &slen, "\"%s\"", tempstring); + if(!domainname_has_safe_characters(tempstring, strlen(tempstring))) { + log_err("ipsecmod: qname has unsafe characters"); + free(tempstring); + return 0; + } + w += sldns_str_print(&s, &slen, "\"%s\"", tempstring); free(tempstring); /* Put space into the buffer. */ - sldns_str_print(&s, &slen, " "); + w += sldns_str_print(&s, &slen, " "); /* Copy the IPSECKEY TTL into the buffer. */ rrset_data = (struct packed_rrset_data*)iq->ipseckey_rrset->entry.data; - sldns_str_print(&s, &slen, "\"%ld\"", (long)rrset_data->ttl); + w += sldns_str_print(&s, &slen, "\"%ld\"", (long)rrset_data->ttl); /* Put space into the buffer. */ - sldns_str_print(&s, &slen, " "); - /* Copy the A/AAAA record(s) into the buffer. Start and end this section - * with a double quote. */ + w += sldns_str_print(&s, &slen, " "); rrset_key = reply_find_answer_rrset(&qstate->return_msg->qinfo, qstate->return_msg->rep); + /* Double check that the records are indeed A/AAAA. + * This should never happen as this function is only executed for A/AAAA + * queries but make sure we don't pass anything other than A/AAAA to the + * shell. */ + qtype = ntohs(rrset_key->rk.type); + if(qtype != LDNS_RR_TYPE_AAAA && qtype != LDNS_RR_TYPE_A) { + log_err("ipsecmod: Answer is not of A or AAAA type"); + return 0; + } rrset_data = (struct packed_rrset_data*)rrset_key->entry.data; - sldns_str_print(&s, &slen, "\""); + /* Copy the A/AAAA record(s) into the buffer. Start and end this section + * with a double quote. */ + w += sldns_str_print(&s, &slen, "\""); for(i=0; i<rrset_data->count; i++) { if(i > 0) { /* Put space into the buffer. */ - sldns_str_print(&s, &slen, " "); + w += sldns_str_print(&s, &slen, " "); } /* Ignore the first two bytes, they are the rr_data len. */ - w = sldns_wire2str_rdata_buf(rrset_data->rr_data[i] + 2, + w_temp = sldns_wire2str_rdata_buf(rrset_data->rr_data[i] + 2, rrset_data->rr_len[i] - 2, s, slen, qstate->qinfo.qtype); - if(w < 0) { + if(w_temp < 0) { /* Error in printout. */ - return -1; - } else if((size_t)w >= slen) { + log_err("ipsecmod: Error in printing IP address"); + return 0; + } else if((size_t)w_temp >= slen) { s = NULL; /* We do not want str to point outside of buffer. */ slen = 0; - return -1; + log_err("ipsecmod: shell command too long"); + return 0; } else { - s += w; - slen -= w; + s += w_temp; + slen -= w_temp; + w += w_temp; } } - sldns_str_print(&s, &slen, "\""); + w += sldns_str_print(&s, &slen, "\""); /* Put space into the buffer. */ - sldns_str_print(&s, &slen, " "); + w += sldns_str_print(&s, &slen, " "); /* Copy the IPSECKEY record(s) into the buffer. Start and end this section * with a double quote. */ - sldns_str_print(&s, &slen, "\""); + w += sldns_str_print(&s, &slen, "\""); rrset_data = (struct packed_rrset_data*)iq->ipseckey_rrset->entry.data; for(i=0; i<rrset_data->count; i++) { if(i > 0) { /* Put space into the buffer. */ - sldns_str_print(&s, &slen, " "); + w += sldns_str_print(&s, &slen, " "); } /* Ignore the first two bytes, they are the rr_data len. */ tempdata = rrset_data->rr_data[i] + 2; tempdata_len = rrset_data->rr_len[i] - 2; /* Save the buffer pointers. */ tempstring = s; tempstring_len = slen; - w = sldns_wire2str_ipseckey_scan(&tempdata, &tempdata_len, &s, &slen, - NULL, 0); + w_temp = sldns_wire2str_ipseckey_scan(&tempdata, &tempdata_len, &s, + &slen, NULL, 0); /* There was an error when parsing the IPSECKEY; reset the buffer * pointers to their previous values. */ - if(w == -1){ + if(w_temp == -1) { s = tempstring; slen = tempstring_len; + } else if(w_temp > 0) { + if(!ipseckey_has_safe_characters( + tempstring, tempstring_len - slen)) { + log_err("ipsecmod: ipseckey has unsafe characters"); + return 0; + } + w += w_temp; } } - sldns_str_print(&s, &slen, "\""); - verbose(VERB_ALGO, "ipsecmod: hook command: '%s'", str); + w += sldns_str_print(&s, &slen, "\""); + if(w >= (int)sizeof(str)) { + log_err("ipsecmod: shell command too long"); + return 0; + } + verbose(VERB_ALGO, "ipsecmod: shell command: '%s'", str); /* ipsecmod-hook should return 0 on success. */ if(system(str) != 0) return 0;
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