X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/bd8fbe3606d80e5a3fc02fe71b521146c6938448..9e70917d0aa5e51f584b2af69ce80df458ac5c79:/src/src/dkim.c diff --git a/src/src/dkim.c b/src/src/dkim.c index 3573e45e6..ea2007225 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 - 2016 */ +/* Copyright (c) University of Cambridge, 1995 - 2017 */ /* See the file NOTICE for conditions of use and distribution. */ /* Code for DKIM support. Other DKIM relevant code is in @@ -18,7 +18,13 @@ int dkim_verify_oldpool; pdkim_ctx *dkim_verify_ctx = NULL; pdkim_signature *dkim_signatures = NULL; pdkim_signature *dkim_cur_sig = NULL; -static BOOL dkim_collect_error = FALSE; +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) @@ -48,7 +54,7 @@ for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS); uschar len = rr->data[rr_offset++]; snprintf(answer + answer_offset, PDKIM_DNS_TXT_MAX_RECLEN - answer_offset, - "%.*s", (int)len, (char *) (rr->data + rr_offset)); + "%.*s", (int)len, CS (rr->data + rr_offset)); rr_offset += len; answer_offset += len; if (answer_offset >= PDKIM_DNS_TXT_MAX_RECLEN) @@ -88,7 +94,7 @@ if (dkim_verify_ctx) dkim_verify_ctx = pdkim_init_verify(&dkim_exim_query_dns_txt, dot_stuffing); dkim_collect_input = !!dkim_verify_ctx; -dkim_collect_error = FALSE; +dkim_collect_error = NULL; /* Start feed up with any cached data */ receive_get_cache(); @@ -104,11 +110,11 @@ int rc; store_pool = POOL_PERM; if ( dkim_collect_input - && (rc = pdkim_feed(dkim_verify_ctx, CS data, len)) != PDKIM_OK) + && (rc = pdkim_feed(dkim_verify_ctx, data, len)) != PDKIM_OK) { + dkim_collect_error = pdkim_errstr(rc); log_write(0, LOG_MAIN, - "DKIM: validation error: %.100s", pdkim_errstr(rc)); - dkim_collect_error = TRUE; + "DKIM: validation error: %.100s", dkim_collect_error); dkim_collect_input = FALSE; } store_pool = dkim_verify_oldpool; @@ -118,23 +124,22 @@ store_pool = dkim_verify_oldpool; void dkim_exim_verify_finish(void) { -pdkim_signature *sig = NULL; -int dkim_signers_size = 0; -int dkim_signers_ptr = 0; -dkim_signers = NULL; -int rc; +pdkim_signature * sig = NULL; +int dkim_signers_size = 0, dkim_signers_ptr = 0, rc; +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 while running this message through validation," - " disabling signature verification."); + "DKIM: Error during validation, disabling signature verification: %.100s", + dkim_collect_error); dkim_disable_verify = TRUE; goto out; } @@ -143,46 +148,47 @@ dkim_collect_input = FALSE; /* Finish DKIM operation and fetch link to signatures chain */ -if ((rc = pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures)) != PDKIM_OK) +rc = pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures, &errstr); +if (rc != PDKIM_OK) { - log_write(0, LOG_MAIN, - "DKIM: validation error: %.100s", pdkim_errstr(rc)); + 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) { - int size = 0; - int ptr = 0; + int size = 0, ptr = 0; + uschar * logmsg = NULL, * s; /* Log a line for each signature */ - uschar *logmsg = string_append(NULL, &size, &ptr, 5, - string_sprintf("d=%s s=%s c=%s/%s a=%s b=%d ", - sig->domain, - sig->selector, - sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", - sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", - sig->algo == PDKIM_ALGO_RSA_SHA256 - ? "rsa-sha256" - : sig->algo == PDKIM_ALGO_RSA_SHA1 ? "rsa-sha1" : "err", - (int)sig->sigdata.len > -1 ? sig->sigdata.len * 8 : 0 - ), - - sig->identity ? string_sprintf("i=%s ", sig->identity) : US"", - sig->created > 0 ? string_sprintf("t=%lu ", sig->created) : US"", - sig->expires > 0 ? string_sprintf("x=%lu ", sig->expires) : US"", - sig->bodylength > -1 ? string_sprintf("l=%lu ", sig->bodylength) : US"" - ); + if (!(s = sig->domain)) s = US""; + logmsg = string_append(logmsg, &size, &ptr, 2, "d=", s); + if (!(s = sig->selector)) s = US""; + logmsg = string_append(logmsg, &size, &ptr, 2, " s=", s); + logmsg = string_append(logmsg, &size, &ptr, 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=%d", + (int)sig->sighash.len > -1 ? sig->sighash.len * 8 : 0)); + if ((s= sig->identity)) logmsg = string_append(logmsg, &size, &ptr, 2, " i=", s); + if (sig->created > 0) logmsg = string_append(logmsg, &size, &ptr, 1, + string_sprintf(" t=%lu", sig->created)); + if (sig->expires > 0) logmsg = string_append(logmsg, &size, &ptr, 1, + string_sprintf(" x=%lu", sig->expires)); + if (sig->bodylength > -1) logmsg = string_append(logmsg, &size, &ptr, 1, + string_sprintf(" l=%lu", sig->bodylength)); switch (sig->verify_status) { case PDKIM_VERIFY_NONE: - logmsg = string_append(logmsg, &size, &ptr, 1, "[not verified]"); + logmsg = string_append(logmsg, &size, &ptr, 1, " [not verified]"); break; case PDKIM_VERIFY_INVALID: - logmsg = string_append(logmsg, &size, &ptr, 1, "[invalid - "); + logmsg = string_append(logmsg, &size, &ptr, 1, " [invalid - "); switch (sig->verify_ext_status) { case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: @@ -219,7 +225,7 @@ for (sig = dkim_signatures; sig; sig = sig->next) case PDKIM_VERIFY_FAIL: logmsg = - string_append(logmsg, &size, &ptr, 1, "[verification failed - "); + string_append(logmsg, &size, &ptr, 1, " [verification failed - "); switch (sig->verify_ext_status) { case PDKIM_VERIFY_FAIL_BODY: @@ -239,7 +245,7 @@ for (sig = dkim_signatures; sig; sig = sig->next) case PDKIM_VERIFY_PASS: logmsg = - string_append(logmsg, &size, &ptr, 1, "[verification succeeded]"); + string_append(logmsg, &size, &ptr, 1, " [verification succeeded]"); break; } @@ -248,27 +254,17 @@ for (sig = dkim_signatures; sig; sig = sig->next) /* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */ - dkim_signers = string_append(dkim_signers, - &dkim_signers_size, - &dkim_signers_ptr, 2, sig->domain, ":"); + if (sig->domain) + dkim_signers = string_append_listele(dkim_signers, &dkim_signers_size, + &dkim_signers_ptr, ':', sig->domain); if (sig->identity) - dkim_signers = string_append(dkim_signers, - &dkim_signers_size, - &dkim_signers_ptr, 2, sig->identity, ":"); + dkim_signers = string_append_listele(dkim_signers, &dkim_signers_size, + &dkim_signers_ptr, ':', sig->identity); /* Process next signature */ } -/* NULL-terminate and chop the last colon from the domain list */ - -if (dkim_signers) - { - dkim_signers[dkim_signers_ptr] = '\0'; - if (Ustrlen(dkim_signers) > 0) - dkim_signers[Ustrlen(dkim_signers) - 1] = '\0'; - } - out: store_pool = dkim_verify_oldpool; } @@ -305,7 +301,7 @@ for (sig = dkim_signatures; sig; sig = sig->next) dkim_signing_domain = US sig->domain; dkim_signing_selector = US sig->selector; - dkim_key_length = sig->sigdata.len * 8; + dkim_key_length = sig->sighash.len * 8; return; } } @@ -346,12 +342,7 @@ if (!dkim_verify_ctx || dkim_disable_verify || !dkim_cur_sig) switch (what) { case DKIM_ALGO: - switch (dkim_cur_sig->algo) - { - case PDKIM_ALGO_RSA_SHA1: return US"rsa-sha1"; - case PDKIM_ALGO_RSA_SHA256: - default: return US"rsa-sha256"; - } + return dkim_sig_to_a_tag(dkim_cur_sig); case DKIM_BODYLENGTH: return dkim_cur_sig->bodylength >= 0 @@ -458,33 +449,33 @@ switch (what) } -uschar * -dkim_exim_sign(int dkim_fd, struct ob_dkim * dkim) +/* Generate signatures for the given file, returning a string. +If a prefix is given, prepend it to the file for the calculations. +*/ + +blob * +dkim_exim_sign(int fd, off_t off, uschar * prefix, + struct ob_dkim * dkim, const uschar ** errstr) { const uschar * dkim_domain; int sep = 0; -uschar *seen_items = NULL; -int seen_items_size = 0; -int seen_items_offset = 0; -uschar itembuf[256]; -uschar *dkim_canon_expanded; -uschar *dkim_sign_headers_expanded; -uschar *dkim_private_key_expanded; -pdkim_ctx *ctx = NULL; -uschar *rc = NULL; -uschar *sigbuf = NULL; +uschar * seen_doms = NULL; +int seen_doms_size = 0; +int seen_doms_offset = 0; +pdkim_ctx ctx; +pdkim_signature * sig; +blob * sigbuf = NULL; int sigsize = 0; -int sigptr = 0; -pdkim_signature *signature; -int pdkim_canon; int pdkim_rc; int sread; -char buf[4096]; +uschar buf[4096]; int save_errno = 0; int old_pool = store_pool; store_pool = POOL_MAIN; +pdkim_init_context(&ctx, dkim->dot_stuffed, &dkim_exim_query_dns_txt); + if (!(dkim_domain = expand_cstring(dkim->dkim_domain))) { /* expansion error, do not send message. */ @@ -495,34 +486,28 @@ if (!(dkim_domain = expand_cstring(dkim->dkim_domain))) /* Set $dkim_domain expansion variable to each unique domain in list. */ -while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, - itembuf, sizeof(itembuf)))) +while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, NULL, 0))) { - if (!dkim_signing_domain || dkim_signing_domain[0] == '\0') + const uschar * dkim_sel; + int sel_sep = 0; + + if (dkim_signing_domain[0] == '\0') continue; /* Only sign once for each domain, no matter how often it appears in the expanded list. */ - if (seen_items) - { - const uschar *seen_items_list = seen_items; - if (match_isinlist(dkim_signing_domain, - &seen_items_list, 0, NULL, NULL, MCL_STRING, TRUE, - NULL) == OK) - continue; - - seen_items = - string_append(seen_items, &seen_items_size, &seen_items_offset, 1, ":"); - } + if (match_isinlist(dkim_signing_domain, CUSS &seen_doms, + 0, NULL, NULL, MCL_STRING, TRUE, NULL) == OK) + continue; - seen_items = - string_append(seen_items, &seen_items_size, &seen_items_offset, 1, - dkim_signing_domain); - seen_items[seen_items_offset] = '\0'; + seen_doms = string_append_listele(seen_doms, &seen_doms_size, + &seen_doms_offset, ':', dkim_signing_domain); - /* Set up $dkim_selector expansion variable. */ + /* Set $dkim_selector expansion variable to each selector in list, + for this domain. */ + if (!(dkim_sel = expand_string(dkim->dkim_selector))) if (!(dkim_signing_selector = expand_string(dkim->dkim_selector))) { log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand " @@ -530,140 +515,184 @@ while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, goto bad; } - /* Get canonicalization to use */ - - dkim_canon_expanded = dkim->dkim_canon - ? expand_string(dkim->dkim_canon) : US"relaxed"; - if (!dkim_canon_expanded) + while ((dkim_signing_selector = string_nextinlist(&dkim_sel, &sel_sep, + NULL, 0))) { - /* expansion error, do not send message. */ - log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand " - "dkim_canon: %s", expand_string_message); - goto bad; - } + uschar * dkim_canon_expanded; + int pdkim_canon; + uschar * dkim_sign_headers_expanded = NULL; + uschar * dkim_private_key_expanded; + uschar * dkim_hash_expanded; - if (Ustrcmp(dkim_canon_expanded, "relaxed") == 0) - pdkim_canon = PDKIM_CANON_RELAXED; - else if (Ustrcmp(dkim_canon_expanded, "simple") == 0) - pdkim_canon = PDKIM_CANON_SIMPLE; - else - { - log_write(0, LOG_MAIN, - "DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n", - dkim_canon_expanded); - pdkim_canon = PDKIM_CANON_RELAXED; - } + /* Get canonicalization to use */ - dkim_sign_headers_expanded = NULL; - if (dkim->dkim_sign_headers) - if (!(dkim_sign_headers_expanded = expand_string(dkim->dkim_sign_headers))) + dkim_canon_expanded = dkim->dkim_canon + ? expand_string(dkim->dkim_canon) : US"relaxed"; + if (!dkim_canon_expanded) { + /* expansion error, do not send message. */ log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand " - "dkim_sign_headers: %s", expand_string_message); + "dkim_canon: %s", expand_string_message); goto bad; } - /* else pass NULL, which means default header list */ - /* Get private key to use. */ - - if (!(dkim_private_key_expanded = expand_string(dkim->dkim_private_key))) - { - log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand " - "dkim_private_key: %s", expand_string_message); - goto bad; - } + if (Ustrcmp(dkim_canon_expanded, "relaxed") == 0) + pdkim_canon = PDKIM_CANON_RELAXED; + else if (Ustrcmp(dkim_canon_expanded, "simple") == 0) + pdkim_canon = PDKIM_CANON_SIMPLE; + else + { + log_write(0, LOG_MAIN, + "DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n", + dkim_canon_expanded); + pdkim_canon = PDKIM_CANON_RELAXED; + } - if ( Ustrlen(dkim_private_key_expanded) == 0 - || Ustrcmp(dkim_private_key_expanded, "0") == 0 - || Ustrcmp(dkim_private_key_expanded, "false") == 0 - ) - continue; /* don't sign, but no error */ + if (dkim->dkim_sign_headers) + if (!(dkim_sign_headers_expanded = expand_string(dkim->dkim_sign_headers))) + { + log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand " + "dkim_sign_headers: %s", expand_string_message); + goto bad; + } + /* else pass NULL, which means default header list */ - if (dkim_private_key_expanded[0] == '/') - { - int privkey_fd = 0; + /* Get private key to use. */ - /* Looks like a filename, load the private key. */ + if (!(dkim_private_key_expanded = expand_string(dkim->dkim_private_key))) + { + log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand " + "dkim_private_key: %s", expand_string_message); + goto bad; + } - memset(big_buffer, 0, big_buffer_size); + if ( Ustrlen(dkim_private_key_expanded) == 0 + || Ustrcmp(dkim_private_key_expanded, "0") == 0 + || Ustrcmp(dkim_private_key_expanded, "false") == 0 + ) + continue; /* don't sign, but no error */ - if ((privkey_fd = open(CS dkim_private_key_expanded, O_RDONLY)) < 0) + if (dkim_private_key_expanded[0] == '/') { - log_write(0, LOG_MAIN | LOG_PANIC, "unable to open " - "private key file for reading: %s", - dkim_private_key_expanded); - goto bad; + int privkey_fd, off = 0, len; + + /* Looks like a filename, load the private key. */ + + memset(big_buffer, 0, big_buffer_size); + + if ((privkey_fd = open(CS dkim_private_key_expanded, O_RDONLY)) < 0) + { + log_write(0, LOG_MAIN | LOG_PANIC, "unable to open " + "private key file for reading: %s", + dkim_private_key_expanded); + goto bad; + } + + do + { + if ((len = read(privkey_fd, big_buffer + off, big_buffer_size - 2 - off)) < 0) + { + (void) close(privkey_fd); + log_write(0, LOG_MAIN|LOG_PANIC, "unable to read private key file: %s", + dkim_private_key_expanded); + goto bad; + } + off += len; + } + while (len > 0); + + (void) close(privkey_fd); + big_buffer[off] = '\0'; + dkim_private_key_expanded = big_buffer; } - if (read(privkey_fd, big_buffer, big_buffer_size - 2) < 0) + if (!(dkim_hash_expanded = expand_string(dkim->dkim_hash))) { - log_write(0, LOG_MAIN|LOG_PANIC, "unable to read private key file: %s", - dkim_private_key_expanded); + log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand " + "dkim_hash: %s", expand_string_message); goto bad; } - (void) close(privkey_fd); - dkim_private_key_expanded = big_buffer; - } + /*XXX so we currently nail signing to RSA + this hash. + Need to extract algo from privkey and check for disallowed combos. */ - ctx = pdkim_init_sign(CS dkim_signing_domain, - CS dkim_signing_selector, - CS dkim_private_key_expanded, - PDKIM_ALGO_RSA_SHA256, - dkim->dot_stuffed, - &dkim_exim_query_dns_txt - ); - dkim_private_key_expanded[0] = '\0'; - pdkim_set_optional(ctx, - CS dkim_sign_headers_expanded, - NULL, - pdkim_canon, - pdkim_canon, -1, 0, 0); - - lseek(dkim_fd, 0, SEEK_SET); - - while ((sread = read(dkim_fd, &buf, sizeof(buf))) > 0) - if ((pdkim_rc = pdkim_feed(ctx, buf, sread)) != PDKIM_OK) - goto pk_bad; + if (!(sig = pdkim_init_sign(&ctx, dkim_signing_domain, + dkim_signing_selector, + dkim_private_key_expanded, + dkim_hash_expanded, + errstr + ))) + goto bad; + dkim_private_key_expanded[0] = '\0'; - /* Handle failed read above. */ - if (sread == -1) - { - debug_printf("DKIM: Error reading -K file.\n"); - save_errno = errno; - goto bad; + pdkim_set_optional(sig, + CS dkim_sign_headers_expanded, + NULL, + pdkim_canon, + pdkim_canon, -1, 0, 0); + + if (!ctx.sig) /* link sig to context chain */ + ctx.sig = sig; + else + { + pdkim_signature * n = ctx.sig; + while (n->next) n = n->next; + n->next = sig; + } } + } - if ((pdkim_rc = pdkim_feed_finish(ctx, &signature)) != PDKIM_OK) - goto pk_bad; +if (prefix) + pdkim_feed(&ctx, prefix, Ustrlen(prefix)); - sigbuf = string_append(sigbuf, &sigsize, &sigptr, 2, - US signature->signature_header, US"\r\n"); +if (lseek(fd, off, SEEK_SET) < 0) + sread = -1; +else + while ((sread = read(fd, &buf, sizeof(buf))) > 0) + if ((pdkim_rc = pdkim_feed(&ctx, buf, sread)) != PDKIM_OK) + goto pk_bad; - pdkim_free_ctx(ctx); - ctx = NULL; +/* Handle failed read above. */ +if (sread == -1) + { + debug_printf("DKIM: Error reading -K file.\n"); + save_errno = errno; + goto bad; } -if (sigbuf) +/* Build string of headers, one per signature */ + +if ((pdkim_rc = pdkim_feed_finish(&ctx, &sig, errstr)) != PDKIM_OK) + goto pk_bad; + +sigbuf = store_get(sizeof(blob)); +sigbuf->data = NULL; +sigbuf->len = 0; + +while (sig) { - sigbuf[sigptr] = '\0'; - rc = sigbuf; + int len = sigbuf->len; + sigbuf->data = string_append(sigbuf->data, &sigsize, &len, 2, + US sig->signature_header, US"\r\n"); + sigbuf->len = len; + sig = sig->next; } + +if (sigbuf->data) + sigbuf->data[sigbuf->len] = '\0'; else - rc = US""; + sigbuf->data = US""; CLEANUP: - if (ctx) - pdkim_free_ctx(ctx); store_pool = old_pool; errno = save_errno; - return rc; + return sigbuf; pk_bad: log_write(0, LOG_MAIN|LOG_PANIC, "DKIM: signing failed: %.100s", pdkim_errstr(pdkim_rc)); bad: - rc = NULL; + sigbuf = NULL; goto CLEANUP; }