X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/a2701501f3e077cba8d3da47e0a5522acffcee3c..286b9d5fa4344de72fe6575fa089237fd7dbb56f:/src/src/dkim.c diff --git a/src/src/dkim.c b/src/src/dkim.c index d31cae9c7..c7bf64152 100644 --- a/src/src/dkim.c +++ b/src/src/dkim.c @@ -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? */ } @@ -134,140 +142,164 @@ store_pool = dkim_verify_oldpool; } -void -dkim_exim_verify_finish(void) +/* Log the result for the given signature */ +static void +dkim_exim_verify_log_sig(pdkim_signature * sig) { -pdkim_signature * sig = NULL; -int rc; -gstring * g = NULL; -const uschar * errstr; - -store_pool = POOL_PERM; - -/* Delete eventual previous signature chain */ - -dkim_signers = NULL; -dkim_signatures = NULL; - -if (dkim_collect_error) - { - log_write(0, LOG_MAIN, - "DKIM: Error during validation, disabling signature verification: %.100s", - dkim_collect_error); - dkim_disable_verify = TRUE; - goto out; - } - -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; - } - -for (sig = dkim_signatures; sig; sig = sig->next) - { - uschar * s; - gstring * logmsg; - - /* Log a line for each signature */ - - if (!(s = sig->domain)) s = US""; - logmsg = string_append(NULL, 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), - 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); - if (sig->created > 0) logmsg = string_cat(logmsg, - string_sprintf(" t=%lu", sig->created)); - if (sig->expires > 0) logmsg = string_cat(logmsg, - string_sprintf(" x=%lu", sig->expires)); - if (sig->bodylength > -1) logmsg = string_cat(logmsg, - string_sprintf(" l=%lu", sig->bodylength)); - +gstring * logmsg; +uschar * s; + +if (!sig) return; + +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); + +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), +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); +if (sig->created > 0) logmsg = string_cat(logmsg, + string_sprintf(" t=%lu", sig->created)); +if (sig->expires > 0) logmsg = string_cat(logmsg, + string_sprintf(" x=%lu", sig->expires)); +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) + ) ) switch (sig->verify_status) { case PDKIM_VERIFY_NONE: - logmsg = string_cat(logmsg, " [not verified]"); + logmsg = string_cat(logmsg, US" [not verified]"); break; case PDKIM_VERIFY_INVALID: - logmsg = string_cat(logmsg, " [invalid - "); + logmsg = string_cat(logmsg, US" [invalid - "); switch (sig->verify_ext_status) { case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: logmsg = string_cat(logmsg, - "public key record (currently?) unavailable]"); + US"public key record (currently?) unavailable]"); break; case PDKIM_VERIFY_INVALID_BUFFER_SIZE: - logmsg = string_cat(logmsg, "overlong public key record]"); + logmsg = string_cat(logmsg, US"overlong public key record]"); break; case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: - logmsg = string_cat(logmsg, "syntax error in public key record]"); + logmsg = string_cat(logmsg, US"syntax error in public key record]"); break; - case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: - logmsg = string_cat(logmsg, "signature tag missing or invalid]"); - break; + case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: + logmsg = string_cat(logmsg, US"signature tag missing or invalid]"); + break; - case PDKIM_VERIFY_INVALID_DKIM_VERSION: - logmsg = string_cat(logmsg, "unsupported DKIM version]"); - break; + case PDKIM_VERIFY_INVALID_DKIM_VERSION: + logmsg = string_cat(logmsg, US"unsupported DKIM version]"); + break; default: - logmsg = string_cat(logmsg, "unspecified problem]"); + logmsg = string_cat(logmsg, US"unspecified problem]"); } break; case PDKIM_VERIFY_FAIL: - logmsg = - string_cat(logmsg, " [verification failed - "); + logmsg = string_cat(logmsg, US" [verification failed - "); switch (sig->verify_ext_status) { case PDKIM_VERIFY_FAIL_BODY: logmsg = string_cat(logmsg, - "body hash mismatch (body probably modified in transit)]"); + US"body hash mismatch (body probably modified in transit)]"); break; case PDKIM_VERIFY_FAIL_MESSAGE: logmsg = string_cat(logmsg, - "signature did not verify (headers probably modified in transit)]"); + US"signature did not verify " + "(headers probably modified in transit)]"); break; default: - logmsg = string_cat(logmsg, "unspecified reason]"); + logmsg = string_cat(logmsg, US"unspecified reason]"); } break; case PDKIM_VERIFY_PASS: - logmsg = string_cat(logmsg, " [verification succeeded]"); + 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; +} + + +/* Log a line for each signature */ +void +dkim_exim_verify_log_all(void) +{ +pdkim_signature * sig; +for (sig = dkim_signatures; sig; sig = sig->next) dkim_exim_verify_log_sig(sig); +} + + +void +dkim_exim_verify_finish(void) +{ +pdkim_signature * sig; +int rc; +gstring * g = NULL; +const uschar * errstr = NULL; + +store_pool = POOL_PERM; - log_write(0, LOG_MAIN, "DKIM: %s", string_from_gstring(logmsg)); +/* Delete eventual previous signature chain */ - /* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */ +dkim_signers = NULL; +dkim_signatures = NULL; - if (sig->domain) - g = string_append_listele(g, ':', sig->domain); +if (dkim_collect_error) + { + log_write(0, LOG_MAIN, + "DKIM: Error during validation, disabling signature verification: %.100s", + dkim_collect_error); + dkim_disable_verify = TRUE; + goto out; + } - if (sig->identity) - g = string_append_listele(g, ':', sig->identity); +dkim_collect_input = FALSE; - /* Process next signature */ +/* Finish DKIM operation and fetch link to signatures chain */ + +rc = pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures, &errstr); +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 */ + +for (sig = dkim_signatures; sig; sig = sig->next) + { + if (sig->domain) g = string_append_listele(g, ':', sig->domain); + if (sig->identity) g = string_append_listele(g, ':', sig->identity); } if (g) dkim_signers = g->s; @@ -277,40 +309,93 @@ store_pool = dkim_verify_oldpool; } -void -dkim_exim_acl_setup(uschar * id) + +/* Args as per dkim_exim_acl_run() below */ +static int +dkim_acl_call(uschar * id, gstring ** res_ptr, + uschar ** user_msgptr, uschar ** log_msgptr) +{ +int rc; +DEBUG(D_receive) + debug_printf("calling acl_smtp_dkim for dkim_cur_signer='%s'\n", id); + +rc = acl_check(ACL_WHERE_DKIM, NULL, acl_smtp_dkim, user_msgptr, log_msgptr); +dkim_exim_verify_log_sig(dkim_cur_sig); +*res_ptr = string_append_listele(*res_ptr, ':', dkim_verify_status); +return rc; +} + + + +/* For the given identity, run the DKIM ACL once for each matching signature. + +Arguments + id Identity to look for in dkim signatures + res_ptr ptr to growable string-list of status results, + appended to per ACL run + user_msgptr where to put a user error (for SMTP response) + log_msgptr where to put a logging message (not for SMTP response) + +Returns: OK access is granted by an ACCEPT verb + DISCARD access is granted by a DISCARD verb + FAIL access is denied + FAIL_DROP access is denied; drop the connection + DEFER can't tell at the moment + ERROR disaster +*/ + +int +dkim_exim_acl_run(uschar * id, gstring ** res_ptr, + uschar ** user_msgptr, uschar ** log_msgptr) { pdkim_signature * sig; uschar * cmp_val; +int rc = -1; -dkim_cur_sig = NULL; +dkim_verify_status = US"none"; +dkim_verify_reason = US""; dkim_cur_signer = id; if (dkim_disable_verify || !id || !dkim_verify_ctx) - return; + return OK; -/* Find signature to run ACL on */ +/* Find signatures to run ACL on */ for (sig = dkim_signatures; sig; sig = sig->next) if ( (cmp_val = Ustrchr(id, '@') != NULL ? US sig->identity : US sig->domain) && strcmpic(cmp_val, id) == 0 ) { - dkim_cur_sig = sig; - /* The "dkim_domain" and "dkim_selector" expansion variables have - related globals, since they are used in the signing code too. - Instead of inventing separate names for verification, we set - them here. This is easy since a domain and selector is guaranteed - to be in a signature. The other dkim_* expansion items are - dynamically fetched from dkim_cur_sig at expansion time (see - function below). */ + related globals, since they are used in the signing code too. + Instead of inventing separate names for verification, we set + them here. This is easy since a domain and selector is guaranteed + to be in a signature. The other dkim_* expansion items are + dynamically fetched from dkim_cur_sig at expansion time (see + function below). */ + dkim_cur_sig = sig; dkim_signing_domain = US sig->domain; dkim_signing_selector = US sig->selector; dkim_key_length = sig->sighash.len * 8; - return; + + /* These two return static strings, so we can compare the addr + later to see if the ACL overwrote them. Check that when logging */ + + 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; } + +if (rc != -1) + return rc; + +/* No matching sig found. Call ACL once anyway. */ + +dkim_cur_sig = NULL; +return dkim_acl_call(id, res_ptr, user_msgptr, log_msgptr); } @@ -365,12 +450,12 @@ switch (what) } case DKIM_CANON_HEADERS: - switch (dkim_cur_sig->canon_headers) - { - case PDKIM_CANON_RELAXED: return US"relaxed"; - case PDKIM_CANON_SIMPLE: - default: return US"simple"; - } + switch (dkim_cur_sig->canon_headers) + { + case PDKIM_CANON_RELAXED: return US"relaxed"; + case PDKIM_CANON_SIMPLE: + default: return US"simple"; + } case DKIM_COPIEDHEADERS: return dkim_cur_sig->copiedheaders @@ -456,8 +541,12 @@ 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 * @@ -613,10 +702,13 @@ 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 @@ -627,9 +719,15 @@ 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; @@ -654,9 +752,8 @@ 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;