X-Git-Url: https://git.netwichtig.de/gitweb/?a=blobdiff_plain;ds=sidebyside;f=src%2Fsrc%2Fdkim.c;h=092eb55c679cef5b5497e026c116076f965a6b27;hb=cfa8f329e9fddbb6db594761364854e780359ace;hp=6bc711ac14101460e80548571615a16418cfb224;hpb=3af849e2045f7c580d4c533d829dc9d567162d36;p=user%2Fhenk%2Fcode%2Fexim.git diff --git a/src/src/dkim.c b/src/src/dkim.c index 6bc711ac1..092eb55c6 100644 --- a/src/src/dkim.c +++ b/src/src/dkim.c @@ -2,7 +2,7 @@ * Exim - an Internet mail transport agent * *************************************************/ -/* Copyright (c) University of Cambridge, 1995 - 2017 */ +/* Copyright (c) University of Cambridge, 1995 - 2018 */ /* See the file NOTICE for conditions of use and distribution. */ /* Code for DKIM support. Other DKIM relevant code is in @@ -36,19 +36,19 @@ static const uschar * dkim_collect_error = NULL; /*XXX the caller only uses the first record if we return multiple. -Could we hand back an allocated string? */ -static int -dkim_exim_query_dns_txt(char *name, char *answer) +static uschar * +dkim_exim_query_dns_txt(char * name) { dns_answer dnsa; dns_scan dnss; dns_record *rr; +gstring * g = NULL; lookup_dnssec_authenticated = NULL; if (dns_lookup(&dnsa, US name, T_TXT, NULL) != DNS_SUCCEED) - return PDKIM_FAIL; /*XXX better error detail? logging? */ + return NULL; /*XXX better error detail? logging? */ /* Search for TXT record */ @@ -58,25 +58,33 @@ for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS); if (rr->type == T_TXT) { int rr_offset = 0; - int answer_offset = 0; /* Copy record content to the answer buffer */ while (rr_offset < rr->size) { uschar len = rr->data[rr_offset++]; - snprintf(answer + answer_offset, - PDKIM_DNS_TXT_MAX_RECLEN - answer_offset, - "%.*s", (int)len, CS (rr->data + rr_offset)); + + g = string_catn(g, US(rr->data + rr_offset), len); + if (g->ptr >= PDKIM_DNS_TXT_MAX_RECLEN) + goto bad; + rr_offset += len; - answer_offset += len; - if (answer_offset >= PDKIM_DNS_TXT_MAX_RECLEN) - return PDKIM_FAIL; /*XXX better error detail? logging? */ } - return PDKIM_OK; + + /* check if this looks like a DKIM record */ + if (Ustrncmp(g->s, "v=", 2) != 0 || strncasecmp(CS g->s, "v=dkim", 6) == 0) + { + store_reset(g->s + g->ptr + 1); + return string_from_gstring(g); + } + + if (g) g->ptr = 0; /* overwrite previous record */ } -return PDKIM_FAIL; /*XXX better error detail? logging? */ +bad: +if (g) store_reset(g); +return NULL; /*XXX better error detail? logging? */ } @@ -143,15 +151,49 @@ uschar * s; if (!sig) return; +/* Remember the domain for the first pass result */ + +if ( !dkim_verify_overall + && dkim_verify_status + ? Ustrcmp(dkim_verify_status, US"pass") == 0 + : sig->verify_status == PDKIM_VERIFY_PASS + ) + dkim_verify_overall = string_copy(sig->domain); + +/* Rewrite the sig result if the ACL overrode it. This is only +needed because the DMARC code (sigh) peeks at the dkim sigs. +Mark the sig for this having been done. */ + +if ( dkim_verify_status + && ( dkim_verify_status != dkim_exim_expand_query(DKIM_VERIFY_STATUS) + || dkim_verify_reason != dkim_exim_expand_query(DKIM_VERIFY_REASON) + ) ) + { /* overridden by ACL */ + sig->verify_ext_status = -1; + if (Ustrcmp(dkim_verify_status, US"fail") == 0) + sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_FAIL; + else if (Ustrcmp(dkim_verify_status, US"invalid") == 0) + sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_INVALID; + else if (Ustrcmp(dkim_verify_status, US"none") == 0) + sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_NONE; + else if (Ustrcmp(dkim_verify_status, US"pass") == 0) + sig->verify_status = PDKIM_VERIFY_POLICY | PDKIM_VERIFY_PASS; + else + sig->verify_status = -1; + } + +if (!LOGGING(dkim_verbose)) return; + + logmsg = string_catn(NULL, US"DKIM: ", 6); if (!(s = sig->domain)) s = US""; logmsg = string_append(logmsg, 2, "d=", s); if (!(s = sig->selector)) s = US""; logmsg = string_append(logmsg, 2, " s=", s); -logmsg = string_append(logmsg, 7, -" c=", sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", -"/", sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", -" a=", dkim_sig_to_a_tag(sig), +logmsg = string_append(logmsg, 7, + " c=", sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", + "/", sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", + " a=", dkim_sig_to_a_tag(sig), string_sprintf(" b=" SIZE_T_FMT, (int)sig->sighash.len > -1 ? sig->sighash.len * 8 : 0)); if ((s= sig->identity)) logmsg = string_append(logmsg, 2, " i=", s); @@ -162,10 +204,10 @@ if (sig->expires > 0) logmsg = string_cat(logmsg, if (sig->bodylength > -1) logmsg = string_cat(logmsg, string_sprintf(" l=%lu", sig->bodylength)); -if ( !dkim_verify_status - || ( dkim_verify_status == dkim_exim_expand_query(DKIM_VERIFY_STATUS) - && dkim_verify_reason == dkim_exim_expand_query(DKIM_VERIFY_REASON) - ) ) +if (sig->verify_status & PDKIM_VERIFY_POLICY) + logmsg = string_append(logmsg, 5, + US" [", dkim_verify_status, US" - ", dkim_verify_reason, US"]"); +else switch (sig->verify_status) { case PDKIM_VERIFY_NONE: @@ -216,7 +258,7 @@ if ( !dkim_verify_status logmsg = string_cat(logmsg, US"signature did not verify " "(headers probably modified in transit)]"); - break; + break; default: logmsg = string_cat(logmsg, US"unspecified reason]"); @@ -227,9 +269,6 @@ if ( !dkim_verify_status logmsg = string_cat(logmsg, US" [verification succeeded]"); break; } -else - logmsg = string_append(logmsg, 5, - US" [", dkim_verify_status, US" - ", dkim_verify_reason, US"]"); log_write(0, LOG_MAIN, "%s", string_from_gstring(logmsg)); return; @@ -251,7 +290,7 @@ dkim_exim_verify_finish(void) pdkim_signature * sig; int rc; gstring * g = NULL; -const uschar * errstr; +const uschar * errstr = NULL; store_pool = POOL_PERM; @@ -274,12 +313,8 @@ dkim_collect_input = FALSE; /* Finish DKIM operation and fetch link to signatures chain */ rc = pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures, &errstr); -if (rc != PDKIM_OK) - { - log_write(0, LOG_MAIN, "DKIM: validation error: %.100s%s%s", pdkim_errstr(rc), - errstr ? ": " : "", errstr ? errstr : US""); - goto out; - } +if (rc != PDKIM_OK && errstr) + log_write(0, LOG_MAIN, "DKIM: validation error: %s", errstr); /* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */ @@ -371,7 +406,7 @@ for (sig = dkim_signatures; sig; sig = sig->next) dkim_verify_status = dkim_exim_expand_query(DKIM_VERIFY_STATUS); dkim_verify_reason = dkim_exim_expand_query(DKIM_VERIFY_REASON); - + if ((rc = dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr)) != OK) return rc; } @@ -528,8 +563,12 @@ switch (what) } -/* Generate signatures for the given file, returning a string. +/* Generate signatures for the given file. If a prefix is given, prepend it to the file for the calculations. + +Return: + NULL: error; error string written + string: signature header(s), or a zero-length string (not an error) */ gstring * @@ -671,9 +710,6 @@ while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0))) else if (!*dkim_identity_expanded) dkim_identity_expanded = NULL; - /*XXX so we currently nail signing to RSA + this hash. - Need to extract algo from privkey and check for disallowed combos. */ - if (!(sig = pdkim_init_sign(&ctx, dkim_signing_domain, dkim_signing_selector, dkim_private_key_expanded, @@ -685,10 +721,13 @@ while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0))) pdkim_set_optional(sig, CS dkim_sign_headers_expanded, - dkim_identity_expanded, + CS dkim_identity_expanded, pdkim_canon, pdkim_canon, -1, 0, 0); + if (!pdkim_set_bodyhash(&ctx, sig)) + goto bad; + if (!ctx.sig) /* link sig to context chain */ ctx.sig = sig; else @@ -699,9 +738,15 @@ while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0))) } } } +if (!ctx.sig) + { + DEBUG(D_transport) debug_printf("DKIM: no viable signatures to use\n"); + sigbuf = string_get(1); /* return a zero-len string */ + goto CLEANUP; + } -if (prefix) - pdkim_feed(&ctx, prefix, Ustrlen(prefix)); +if (prefix && (pdkim_rc = pdkim_feed(&ctx, prefix, Ustrlen(prefix))) != PDKIM_OK) + goto pk_bad; if (lseek(fd, off, SEEK_SET) < 0) sread = -1; @@ -726,9 +771,8 @@ if ((pdkim_rc = pdkim_feed_finish(&ctx, &sig, errstr)) != PDKIM_OK) for (sigbuf = NULL; sig; sig = sig->next) sigbuf = string_append(sigbuf, 2, US sig->signature_header, US"\r\n"); -(void) string_from_gstring(sigbuf); - CLEANUP: + (void) string_from_gstring(sigbuf); store_pool = old_pool; errno = save_errno; return sigbuf; @@ -746,5 +790,72 @@ expand_bad: goto bad; } + + + +gstring * +authres_dkim(gstring * g) +{ +pdkim_signature * sig; + +for (sig = dkim_signatures; sig; sig = sig->next) + { + g = string_catn(g, US";\n\tdkim=", 8); + + if (sig->verify_status & PDKIM_VERIFY_POLICY) + g = string_append(g, 5, + US"policy (", dkim_verify_status, US" - ", dkim_verify_reason, US")"); + else switch(sig->verify_status) + { + case PDKIM_VERIFY_NONE: g = string_cat(g, US"none"); break; + case PDKIM_VERIFY_INVALID: + switch (sig->verify_ext_status) + { + case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: + g = string_cat(g, US"tmperror (pubkey unavailable)"); break; + case PDKIM_VERIFY_INVALID_BUFFER_SIZE: + g = string_cat(g, US"permerror (overlong public key record)"); break; + case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: + case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: + g = string_cat(g, US"neutral (syntax error in public key record)"); + break; + case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: + g = string_cat(g, US"neutral (signature tag missing or invalid)"); + break; + case PDKIM_VERIFY_INVALID_DKIM_VERSION: + g = string_cat(g, US"neutral (unsupported DKIM version)"); + break; + default: + g = string_cat(g, US"permerror (unspecified problem)"); break; + } + break; + case PDKIM_VERIFY_FAIL: + switch (sig->verify_ext_status) + { + case PDKIM_VERIFY_FAIL_BODY: + g = string_cat(g, + US"fail (body hash mismatch; body probably modified in transit)"); + break; + case PDKIM_VERIFY_FAIL_MESSAGE: + g = string_cat(g, + US"fail (signature did not verify; headers probably modified in transit)"); + break; + default: + g = string_cat(g, US"fail (unspecified reason)"); + break; + } + break; + case PDKIM_VERIFY_PASS: g = string_cat(g, US"pass"); break; + default: g = string_cat(g, US"permerror"); break; + } + if (sig->domain) g = string_append(g, 2, US" header.d=", sig->domain); + if (sig->identity) g = string_append(g, 2, US" header.i=", sig->identity); + if (sig->selector) g = string_append(g, 2, US" header.s=", sig->selector); + g = string_append(g, 2, US" header.a=", dkim_sig_to_a_tag(sig)); + } +return g; +} + + # endif /*!MACRO_PREDEF*/ #endif /*!DISABLE_DKIM*/