X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/4c04137d73637107669e02b21f890387aaa2ef34..e3e281ccf9d8777d0df98ddd644720573e0343d1:/src/src/pdkim/pdkim.c diff --git a/src/src/pdkim/pdkim.c b/src/src/pdkim/pdkim.c index 58838c2ef..05f656df4 100644 --- a/src/src/pdkim/pdkim.c +++ b/src/src/pdkim/pdkim.c @@ -2,7 +2,8 @@ * PDKIM - a RFC4871 (DKIM) implementation * * Copyright (C) 2009 - 2016 Tom Kistner - * Copyright (C) 2016 Jeremy Harris + * Copyright (C) 2016 - 2020 Jeremy Harris + * Copyright (c) The Exim Maintainers 2021 * * http://duncanthrax.net/pdkim/ * @@ -26,23 +27,23 @@ #ifndef DISABLE_DKIM /* entire file */ -#ifndef SUPPORT_TLS -# error Need SUPPORT_TLS for DKIM +#ifdef DISABLE_TLS +# error Must not DISABLE_TLS, for DKIM #endif #include "crypt_ver.h" -#ifdef RSA_OPENSSL +#ifdef SIGN_OPENSSL # include # include # include -#elif defined(RSA_GNUTLS) +#elif defined(SIGN_GNUTLS) # include # include #endif #include "pdkim.h" -#include "rsa.h" +#include "signing.h" #define PDKIM_SIGNATURE_VERSION "1" #define PDKIM_PUB_RECORD_VERSION US "DKIM1" @@ -51,14 +52,6 @@ #define PDKIM_MAX_HEADERS 512 #define PDKIM_MAX_BODY_LINE_LEN 16384 #define PDKIM_DNS_TXT_MAX_NAMELEN 1024 -#define PDKIM_DEFAULT_SIGN_HEADERS "From:Sender:Reply-To:Subject:Date:"\ - "Message-ID:To:Cc:MIME-Version:Content-Type:"\ - "Content-Transfer-Encoding:Content-ID:"\ - "Content-Description:Resent-Date:Resent-From:"\ - "Resent-Sender:Resent-To:Resent-Cc:"\ - "Resent-Message-ID:In-Reply-To:References:"\ - "List-Id:List-Help:List-Unsubscribe:"\ - "List-Subscribe:List-Post:List-Owner:List-Archive" /* -------------------------------------------------------------------------- */ struct pdkim_stringlist { @@ -73,30 +66,35 @@ const uschar * pdkim_querymethods[] = { US"dns/txt", NULL }; -const uschar * pdkim_algos[] = { - US"rsa-sha256", - US"rsa-sha1", - NULL -}; const uschar * pdkim_canons[] = { US"simple", US"relaxed", NULL }; -const uschar * pdkim_hashes[] = { - US"sha256", - US"sha1", - NULL + +const pdkim_hashtype pdkim_hashes[] = { + { US"sha1", HASH_SHA1 }, + { US"sha256", HASH_SHA2_256 }, + { US"sha512", HASH_SHA2_512 } }; + const uschar * pdkim_keytypes[] = { - US"rsa", - NULL + [KEYTYPE_RSA] = US"rsa", +#ifdef SIGN_HAVE_ED25519 + [KEYTYPE_ED25519] = US"ed25519", /* Works for 3.6.0 GnuTLS, OpenSSL 1.1.1 */ +#endif + +#ifdef notyet_EC_dkim_extensions /* https://tools.ietf.org/html/draft-srose-dkim-ecc-00 */ + US"eccp256", + US"eccp348", + US"ed448", +#endif }; typedef struct pdkim_combined_canon_entry { - const uschar * str; - int canon_headers; - int canon_body; + const uschar * str; + int canon_headers; + int canon_body; } pdkim_combined_canon_entry; pdkim_combined_canon_entry pdkim_combined_canons[] = { @@ -110,7 +108,54 @@ pdkim_combined_canon_entry pdkim_combined_canons[] = { }; +static const blob lineending = {.data = US"\r\n", .len = 2}; + /* -------------------------------------------------------------------------- */ +uschar * +dkim_sig_to_a_tag(const pdkim_signature * sig) +{ +if ( sig->keytype < 0 || sig->keytype > nelem(pdkim_keytypes) + || sig->hashtype < 0 || sig->hashtype > nelem(pdkim_hashes)) + return US"err"; +return string_sprintf("%s-%s", + pdkim_keytypes[sig->keytype], pdkim_hashes[sig->hashtype].dkim_hashname); +} + + +static int +pdkim_keyname_to_keytype(const uschar * s) +{ +for (int i = 0; i < nelem(pdkim_keytypes); i++) + if (Ustrcmp(s, pdkim_keytypes[i]) == 0) return i; +return -1; +} + +int +pdkim_hashname_to_hashtype(const uschar * s, unsigned len) +{ +if (!len) len = Ustrlen(s); +for (int i = 0; i < nelem(pdkim_hashes); i++) + if (Ustrncmp(s, pdkim_hashes[i].dkim_hashname, len) == 0) + return i; +return -1; +} + +void +pdkim_cstring_to_canons(const uschar * s, unsigned len, + int * canon_head, int * canon_body) +{ +if (!len) len = Ustrlen(s); +for (int i = 0; pdkim_combined_canons[i].str; i++) + if ( Ustrncmp(s, pdkim_combined_canons[i].str, len) == 0 + && len == Ustrlen(pdkim_combined_canons[i].str)) + { + *canon_head = pdkim_combined_canons[i].canon_headers; + *canon_body = pdkim_combined_canons[i].canon_body; + break; + } +} + + const char * pdkim_verify_status_str(int status) @@ -132,41 +177,43 @@ switch(ext_status) { case PDKIM_VERIFY_FAIL_BODY: return "PDKIM_VERIFY_FAIL_BODY"; case PDKIM_VERIFY_FAIL_MESSAGE: return "PDKIM_VERIFY_FAIL_MESSAGE"; + case PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH: return "PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH"; case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: return "PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE"; case PDKIM_VERIFY_INVALID_BUFFER_SIZE: return "PDKIM_VERIFY_INVALID_BUFFER_SIZE"; case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: return "PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD"; case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return "PDKIM_VERIFY_INVALID_PUBKEY_IMPORT"; + case PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE: return "PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE"; case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: return "PDKIM_VERIFY_INVALID_SIGNATURE_ERROR"; case PDKIM_VERIFY_INVALID_DKIM_VERSION: return "PDKIM_VERIFY_INVALID_DKIM_VERSION"; default: return "PDKIM_VERIFY_UNKNOWN"; } } -const char * +const uschar * pdkim_errstr(int status) { switch(status) { - case PDKIM_OK: return "OK"; - case PDKIM_FAIL: return "FAIL"; - case PDKIM_ERR_RSA_PRIVKEY: return "RSA_PRIVKEY"; - case PDKIM_ERR_RSA_SIGNING: return "RSA SIGNING"; - case PDKIM_ERR_LONG_LINE: return "RSA_LONG_LINE"; - case PDKIM_ERR_BUFFER_TOO_SMALL: return "BUFFER_TOO_SMALL"; - case PDKIM_SIGN_PRIVKEY_WRAP: return "PRIVKEY_WRAP"; - case PDKIM_SIGN_PRIVKEY_B64D: return "PRIVKEY_B64D"; - default: return "(unknown)"; + case PDKIM_OK: return US"OK"; + case PDKIM_FAIL: return US"FAIL"; + case PDKIM_ERR_RSA_PRIVKEY: return US"PRIVKEY"; + case PDKIM_ERR_RSA_SIGNING: return US"SIGNING"; + case PDKIM_ERR_LONG_LINE: return US"LONG_LINE"; + case PDKIM_ERR_BUFFER_TOO_SMALL: return US"BUFFER_TOO_SMALL"; + case PDKIM_ERR_EXCESS_SIGS: return US"EXCESS_SIGS"; + case PDKIM_SIGN_PRIVKEY_WRAP: return US"PRIVKEY_WRAP"; + case PDKIM_SIGN_PRIVKEY_B64D: return US"PRIVKEY_B64D"; + default: return US"(unknown)"; } } /* -------------------------------------------------------------------------- */ /* Print debugging functions */ -static void +void pdkim_quoteprint(const uschar *data, int len) { -int i; -for (i = 0; i < len; i++) +for (int i = 0; i < len; i++) { const int c = data[i]; switch (c) @@ -188,11 +235,11 @@ for (i = 0; i < len; i++) debug_printf("\n"); } -static void +void pdkim_hexprint(const uschar *data, int len) { -int i; -for (i = 0 ; i < len; i++) debug_printf("%02x", data[i]); +if (data) for (int i = 0 ; i < len; i++) debug_printf("%02x", data[i]); +else debug_printf(""); debug_printf("\n"); } @@ -201,7 +248,7 @@ debug_printf("\n"); static pdkim_stringlist * pdkim_prepend_stringlist(pdkim_stringlist * base, const uschar * str) { -pdkim_stringlist * new_entry = store_get(sizeof(pdkim_stringlist)); +pdkim_stringlist * new_entry = store_get(sizeof(pdkim_stringlist), FALSE); memset(new_entry, 0, sizeof(pdkim_stringlist)); new_entry->value = string_copy(str); @@ -214,18 +261,20 @@ return new_entry; /* Trim whitespace fore & aft */ static void -pdkim_strtrim(uschar * str) +pdkim_strtrim(gstring * str) { -uschar * p = str; -uschar * q = str; -while (*p == '\t' || *p == ' ') p++; /* skip whitespace */ -while (*p) {*q = *p; q++; p++;} /* dump the leading whitespace */ -*q = '\0'; -while (q != str && ( (*q == '\0') || (*q == '\t') || (*q == ' ') ) ) - { /* dump trailing whitespace */ - *q = '\0'; - q--; - } +uschar * p = str->s; +uschar * q; + +while (*p == '\t' || *p == ' ') /* dump the leading whitespace */ + { str->size--; str->ptr--; str->s++; } + +while ( str->ptr > 0 + && ((q = str->s + str->ptr - 1), (*q == '\t' || *q == ' ')) + ) + str->ptr--; /* dump trailing whitespace */ + +(void) string_from_gstring(str); } @@ -241,16 +290,19 @@ pdkim_free_ctx(pdkim_ctx *ctx) /* -------------------------------------------------------------------------- */ /* Matches the name of the passed raw "header" against the passed colon-separated "tick", and invalidates - the entry in tick. Returns OK or fail-code */ -/*XXX might be safer done using a pdkim_stringlist for "tick" */ + the entry in tick. Entries can be prefixed for multi- or over-signing, + in which case do not invalidate. + + Returns OK for a match, or fail-code +*/ static int header_name_match(const uschar * header, uschar * tick) { -uschar * hname; -uschar * lcopy; -uschar * p; -uschar * q; +const uschar * ticklist = tick; +int sep = ':'; +BOOL multisign; +uschar * hname, * p, * ele; uschar * hcolon = Ustrchr(header, ':'); /* Get header name */ if (!hcolon) @@ -259,47 +311,41 @@ if (!hcolon) /* if we had strncmpic() we wouldn't need this copy */ hname = string_copyn(header, hcolon-header); -/* Copy tick-off list locally, so we can punch zeroes into it */ -p = lcopy = string_copy(tick); - -for (q = Ustrchr(p, ':'); q; q = Ustrchr(p, ':')) +while (p = US ticklist, ele = string_nextinlist(&ticklist, &sep, NULL, 0)) { - *q = '\0'; - if (strcmpic(p, hname) == 0) - goto found; - - p = q+1; + switch (*ele) + { + case '=': case '+': multisign = TRUE; ele++; break; + default: multisign = FALSE; break; } -if (strcmpic(p, hname) == 0) - goto found; - + if (strcmpic(ele, hname) == 0) + { + if (!multisign) + *p = '_'; /* Invalidate this header name instance in tick-off list */ + return PDKIM_OK; + } + } return PDKIM_FAIL; - -found: - /* Invalidate header name instance in tick-off list */ - tick[p-lcopy] = '_'; - return PDKIM_OK; } /* -------------------------------------------------------------------------- */ /* Performs "relaxed" canonicalization of a header. */ -static uschar * -pdkim_relax_header(const uschar * header, int crlf) +uschar * +pdkim_relax_header_n(const uschar * header, int len, BOOL append_crlf) { BOOL past_field_name = FALSE; BOOL seen_wsp = FALSE; -const uschar * p; -uschar * relaxed = store_get(Ustrlen(header)+3); +uschar * relaxed = store_get(len+3, TRUE); /* tainted */ uschar * q = relaxed; -for (p = header; *p; p++) +for (const uschar * p = header; p - header < len; p++) { uschar c = *p; - /* Ignore CR & LF */ - if (c == '\r' || c == '\n') + + if (c == '\r' || c == '\n') /* Ignore CR & LF */ continue; if (c == '\t' || c == ' ') { @@ -311,8 +357,8 @@ for (p = header; *p; p++) else if (!past_field_name && c == ':') { - if (seen_wsp) q--; /* This removes WSP before the colon */ - seen_wsp = TRUE; /* This removes WSP after the colon */ + if (seen_wsp) q--; /* This removes WSP immediately before the colon */ + seen_wsp = TRUE; /* This removes WSP immediately after the colon */ past_field_name = TRUE; } else @@ -325,19 +371,26 @@ for (p = header; *p; p++) if (q > relaxed && q[-1] == ' ') q--; /* Squash eventual trailing SP */ -if (crlf) { *q++ = '\r'; *q++ = '\n'; } +if (append_crlf) { *q++ = '\r'; *q++ = '\n'; } *q = '\0'; return relaxed; } +uschar * +pdkim_relax_header(const uschar * header, BOOL append_crlf) +{ +return pdkim_relax_header_n(header, Ustrlen(header), append_crlf); +} + + /* -------------------------------------------------------------------------- */ #define PDKIM_QP_ERROR_DECODE -1 -static uschar * -pdkim_decode_qp_char(uschar *qp_p, int *c) +static const uschar * +pdkim_decode_qp_char(const uschar *qp_p, int *c) { -uschar *initial_pos = qp_p; +const uschar *initial_pos = qp_p; /* Advance one char */ qp_p++; @@ -360,12 +413,12 @@ return initial_pos; /* -------------------------------------------------------------------------- */ static uschar * -pdkim_decode_qp(uschar * str) +pdkim_decode_qp(const uschar * str) { int nchar = 0; uschar * q; -uschar * p = str; -uschar * n = store_get(Ustrlen(str)+1); +const uschar * p = str; +uschar * n = store_get(Ustrlen(str)+1, TRUE); *n = '\0'; q = n; @@ -391,19 +444,18 @@ return n; /* -------------------------------------------------------------------------- */ -static void -pdkim_decode_base64(uschar *str, blob * b) +void +pdkim_decode_base64(const uschar * str, blob * b) { -int dlen; -dlen = b64decode(str, &b->data); +int dlen = b64decode(str, &b->data); if (dlen < 0) b->data = NULL; b->len = dlen; } -static uschar * +uschar * pdkim_encode_base64(blob * b) { -return b64encode(b->data, b->len); +return b64encode(CUS b->data, b->len); } @@ -413,28 +465,28 @@ return b64encode(b->data, b->len); #define PDKIM_HDR_VALUE 2 static pdkim_signature * -pdkim_parse_sig_header(pdkim_ctx *ctx, uschar * raw_hdr) +pdkim_parse_sig_header(pdkim_ctx * ctx, uschar * raw_hdr) { -pdkim_signature *sig ; -uschar *p, *q; -uschar * cur_tag = NULL; int ts = 0, tl = 0; -uschar * cur_val = NULL; int vs = 0, vl = 0; +pdkim_signature * sig; +uschar *q; +gstring * cur_tag = NULL; +gstring * cur_val = NULL; BOOL past_hname = FALSE; BOOL in_b_val = FALSE; int where = PDKIM_HDR_LIMBO; -int i; -sig = store_get(sizeof(pdkim_signature)); +sig = store_get(sizeof(pdkim_signature), FALSE); memset(sig, 0, sizeof(pdkim_signature)); sig->bodylength = -1; /* Set so invalid/missing data error display is accurate */ -sig->algo = -1; sig->version = 0; +sig->keytype = -1; +sig->hashtype = -1; -q = sig->rawsig_no_b_val = store_get(Ustrlen(raw_hdr)+1); +q = sig->rawsig_no_b_val = store_get(Ustrlen(raw_hdr)+1, TRUE); /* tainted */ -for (p = raw_hdr; ; p++) +for (uschar * p = raw_hdr; ; p++) { char c = *p; @@ -461,12 +513,11 @@ for (p = raw_hdr; ; p++) if (where == PDKIM_HDR_TAG) { if (c >= 'a' && c <= 'z') - cur_tag = string_catn(cur_tag, &ts, &tl, p, 1); + cur_tag = string_catn(cur_tag, p, 1); if (c == '=') { - cur_tag[tl] = '\0'; - if (Ustrcmp(cur_tag, "b") == 0) + if (Ustrcmp(string_from_gstring(cur_tag), "b") == 0) { *q++ = '='; in_b_val = TRUE; @@ -483,80 +534,91 @@ for (p = raw_hdr; ; p++) if (c == ';' || c == '\0') { - if (tl && vl) + /* We must have both tag and value, and tags must be one char except + for the possibility of "bh". */ + + if ( cur_tag && cur_val + && (cur_tag->ptr == 1 || *cur_tag->s == 'b') + ) { - cur_val[vl] = '\0'; + (void) string_from_gstring(cur_val); pdkim_strtrim(cur_val); - DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag, cur_val); + DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag->s, cur_val->s); - switch (*cur_tag) + switch (*cur_tag->s) { - case 'b': - if (cur_tag[1] == 'h') - pdkim_decode_base64(cur_val, &sig->bodyhash); - else - pdkim_decode_base64(cur_val, &sig->sigdata); + case 'b': /* sig-data or body-hash */ + switch (cur_tag->s[1]) + { + case '\0': pdkim_decode_base64(cur_val->s, &sig->sighash); break; + case 'h': if (cur_tag->ptr == 2) + pdkim_decode_base64(cur_val->s, &sig->bodyhash); + break; + default: break; + } break; - case 'v': + case 'v': /* version */ /* We only support version 1, and that is currently the only version there is. */ sig->version = - Ustrcmp(cur_val, PDKIM_SIGNATURE_VERSION) == 0 ? 1 : -1; - break; - case 'a': - for (i = 0; pdkim_algos[i]; i++) - if (Ustrcmp(cur_val, pdkim_algos[i]) == 0) - { - sig->algo = i; - break; - } + Ustrcmp(cur_val->s, PDKIM_SIGNATURE_VERSION) == 0 ? 1 : -1; break; - case 'c': - for (i = 0; pdkim_combined_canons[i].str; i++) - if (Ustrcmp(cur_val, pdkim_combined_canons[i].str) == 0) - { - sig->canon_headers = pdkim_combined_canons[i].canon_headers; - sig->canon_body = pdkim_combined_canons[i].canon_body; - break; - } + case 'a': /* algorithm */ + { + const uschar * list = cur_val->s; + int sep = '-'; + uschar * elem; + + if ((elem = string_nextinlist(&list, &sep, NULL, 0))) + sig->keytype = pdkim_keyname_to_keytype(elem); + if ((elem = string_nextinlist(&list, &sep, NULL, 0))) + for (int i = 0; i < nelem(pdkim_hashes); i++) + if (Ustrcmp(elem, pdkim_hashes[i].dkim_hashname) == 0) + { sig->hashtype = i; break; } + } + + case 'c': /* canonicalization */ + pdkim_cstring_to_canons(cur_val->s, 0, + &sig->canon_headers, &sig->canon_body); break; - case 'q': - for (i = 0; pdkim_querymethods[i]; i++) - if (Ustrcmp(cur_val, pdkim_querymethods[i]) == 0) + case 'q': /* Query method (for pubkey)*/ + for (int i = 0; pdkim_querymethods[i]; i++) + if (Ustrcmp(cur_val->s, pdkim_querymethods[i]) == 0) { - sig->querymethod = i; + sig->querymethod = i; /* we never actually use this */ break; } break; - case 's': - sig->selector = string_copy(cur_val); break; - case 'd': - sig->domain = string_copy(cur_val); break; - case 'i': - sig->identity = pdkim_decode_qp(cur_val); break; - case 't': - sig->created = strtoul(CS cur_val, NULL, 10); break; - case 'x': - sig->expires = strtoul(CS cur_val, NULL, 10); break; - case 'l': - sig->bodylength = strtol(CS cur_val, NULL, 10); break; - case 'h': - sig->headernames = string_copy(cur_val); break; - case 'z': - sig->copiedheaders = pdkim_decode_qp(cur_val); break; + case 's': /* Selector */ + sig->selector = string_copyn(cur_val->s, cur_val->ptr); break; + case 'd': /* SDID */ + sig->domain = string_copyn(cur_val->s, cur_val->ptr); break; + case 'i': /* AUID */ + sig->identity = pdkim_decode_qp(cur_val->s); break; + case 't': /* Timestamp */ + sig->created = strtoul(CS cur_val->s, NULL, 10); break; + case 'x': /* Expiration */ + sig->expires = strtoul(CS cur_val->s, NULL, 10); break; + case 'l': /* Body length count */ + sig->bodylength = strtol(CS cur_val->s, NULL, 10); break; + case 'h': /* signed header fields */ + sig->headernames = string_copyn(cur_val->s, cur_val->ptr); break; + case 'z': /* Copied headfields */ + sig->copiedheaders = pdkim_decode_qp(cur_val->s); break; +/*XXX draft-ietf-dcrup-dkim-crypto-05 would need 'p' tag support +for rsafp signatures. But later discussion is dropping those. */ default: DEBUG(D_acl) debug_printf(" Unknown tag encountered\n"); break; } } - tl = 0; - vl = 0; + cur_tag = cur_val = NULL; in_b_val = FALSE; where = PDKIM_HDR_LIMBO; } else - cur_val = string_catn(cur_val, &vs, &vl, p, 1); + cur_val = string_catn(cur_val, p, 1); } NEXT_CHAR: @@ -567,6 +629,9 @@ NEXT_CHAR: *q++ = c; } +if (sig->keytype < 0 || sig->hashtype < 0) /* Cannot verify this signature */ + return NULL; + *q = '\0'; /* Chomp raw header. The final newline must not be added to the signature. */ while (--q > sig->rawsig_no_b_val && (*q == '\r' || *q == '\n')) @@ -575,355 +640,311 @@ while (--q > sig->rawsig_no_b_val && (*q == '\r' || *q == '\n')) DEBUG(D_acl) { debug_printf( - "PDKIM >> Raw signature w/o b= tag value >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"); + "DKIM >> Raw signature w/o b= tag value >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"); pdkim_quoteprint(US sig->rawsig_no_b_val, Ustrlen(sig->rawsig_no_b_val)); debug_printf( - "PDKIM >> Sig size: %4u bits\n", (unsigned) sig->sigdata.len*8); + "DKIM >> Sig size: %4u bits\n", (unsigned) sig->sighash.len*8); debug_printf( - "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); } -exim_sha_init(&sig->body_hash, sig->algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256); +if (!pdkim_set_sig_bodyhash(ctx, sig)) + return NULL; + return sig; } /* -------------------------------------------------------------------------- */ -static pdkim_pubkey * -pdkim_parse_pubkey_record(pdkim_ctx *ctx, const uschar *raw_record) +pdkim_pubkey * +pdkim_parse_pubkey_record(const uschar *raw_record) { -pdkim_pubkey *pub; -const uschar *p; -uschar * cur_tag = NULL; int ts = 0, tl = 0; -uschar * cur_val = NULL; int vs = 0, vl = 0; -int where = PDKIM_HDR_LIMBO; +const uschar * ele; +int sep = ';'; +pdkim_pubkey * pub; -pub = store_get(sizeof(pdkim_pubkey)); +pub = store_get(sizeof(pdkim_pubkey), TRUE); /* tainted */ memset(pub, 0, sizeof(pdkim_pubkey)); -for (p = raw_record; ; p++) +while ((ele = string_nextinlist(&raw_record, &sep, NULL, 0))) + { + const uschar * val; + + if ((val = Ustrchr(ele, '='))) { - uschar c = *p; + int taglen = val++ - ele; - /* Ignore FWS */ - if (c != '\r' && c != '\n') switch (where) + DEBUG(D_acl) debug_printf(" %.*s=%s\n", taglen, ele, val); + switch (ele[0]) { - case PDKIM_HDR_LIMBO: /* In limbo, just wait for a tag-char to appear */ - if (!(c >= 'a' && c <= 'z')) - break; - where = PDKIM_HDR_TAG; - /*FALLTHROUGH*/ - - case PDKIM_HDR_TAG: - if (c >= 'a' && c <= 'z') - cur_tag = string_catn(cur_tag, &ts, &tl, p, 1); - - if (c == '=') - { - cur_tag[tl] = '\0'; - where = PDKIM_HDR_VALUE; - } - break; - - case PDKIM_HDR_VALUE: - if (c == ';' || c == '\0') - { - if (tl && vl) - { - cur_val[vl] = '\0'; - pdkim_strtrim(cur_val); - DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag, cur_val); - - switch (cur_tag[0]) - { - case 'v': - pub->version = string_copy(cur_val); break; - case 'h': - case 'k': -/* This field appears to never be used. Also, unclear why -a 'k' (key-type_ would go in this field name. There is a field -"keytype", also never used. - pub->hashes = string_copy(cur_val); -*/ - break; - case 'g': - pub->granularity = string_copy(cur_val); break; - case 'n': - pub->notes = pdkim_decode_qp(cur_val); break; - case 'p': - pdkim_decode_base64(US cur_val, &pub->key); break; - case 's': - pub->srvtype = string_copy(cur_val); break; - case 't': - if (Ustrchr(cur_val, 'y') != NULL) pub->testing = 1; - if (Ustrchr(cur_val, 's') != NULL) pub->no_subdomaining = 1; + case 'v': pub->version = val; break; + case 'h': pub->hashes = val; break; + case 'k': pub->keytype = val; break; + case 'g': pub->granularity = val; break; + case 'n': pub->notes = pdkim_decode_qp(val); break; + case 'p': pdkim_decode_base64(val, &pub->key); break; + case 's': pub->srvtype = val; break; + case 't': if (Ustrchr(val, 'y')) pub->testing = 1; + if (Ustrchr(val, 's')) pub->no_subdomaining = 1; break; - default: - DEBUG(D_acl) debug_printf(" Unknown tag encountered\n"); - break; - } - } - tl = 0; - vl = 0; - where = PDKIM_HDR_LIMBO; - } - else - cur_val = string_catn(cur_val, &vs, &vl, p, 1); - break; + default: DEBUG(D_acl) debug_printf(" Unknown tag encountered\n"); break; } - - if (c == '\0') break; } + } /* Set fallback defaults */ -if (!pub->version ) pub->version = string_copy(PDKIM_PUB_RECORD_VERSION); -else if (Ustrcmp(pub->version, PDKIM_PUB_RECORD_VERSION) != 0) return NULL; +if (!pub->version) + pub->version = string_copy(PDKIM_PUB_RECORD_VERSION); +else if (Ustrcmp(pub->version, PDKIM_PUB_RECORD_VERSION) != 0) + { + DEBUG(D_acl) debug_printf(" Bad v= field\n"); + return NULL; + } -if (!pub->granularity) pub->granularity = string_copy(US"*"); -/* -if (!pub->keytype ) pub->keytype = string_copy(US"rsa"); -*/ -if (!pub->srvtype ) pub->srvtype = string_copy(US"*"); +if (!pub->granularity) pub->granularity = US"*"; +if (!pub->keytype ) pub->keytype = US"rsa"; +if (!pub->srvtype ) pub->srvtype = US"*"; /* p= is required */ if (pub->key.data) return pub; +DEBUG(D_acl) debug_printf(" Missing p= field\n"); return NULL; } /* -------------------------------------------------------------------------- */ -static int -pdkim_update_bodyhash(pdkim_ctx *ctx, const char *data, int len) +/* Update one bodyhash with some additional data. +If we have to relax the data for this sig, return our copy of it. */ + +static blob * +pdkim_update_ctx_bodyhash(pdkim_bodyhash * b, const blob * orig_data, blob * relaxed_data) { -pdkim_signature *sig = ctx->sig; -/* Cache relaxed version of data */ -uschar *relaxed_data = NULL; -int relaxed_len = 0; +const blob * canon_data = orig_data; +size_t left; -/* Traverse all signatures, updating their hashes. */ -while (sig) - { - /* Defaults to simple canon (no further treatment necessary) */ - const uschar *canon_data = CUS data; - int canon_len = len; +/* Defaults to simple canon (no further treatment necessary) */ - if (sig->canon_body == PDKIM_CANON_RELAXED) +if (b->canon_method == PDKIM_CANON_RELAXED) + { + /* Relax the line if not done already */ + if (!relaxed_data) { - /* Relax the line if not done already */ - if (!relaxed_data) - { - BOOL seen_wsp = FALSE; - const char *p; - int q = 0; + BOOL seen_wsp = FALSE; + int q = 0; - /* We want to be able to free this else we allocate - for the entire message which could be many MB. Since - we don't know what allocations the SHA routines might - do, not safe to use store_get()/store_reset(). */ + /* We want to be able to free this else we allocate + for the entire message which could be many MB. Since + we don't know what allocations the SHA routines might + do, not safe to use store_get()/store_reset(). */ - relaxed_data = store_malloc(len+1); + relaxed_data = store_malloc(sizeof(blob) + orig_data->len+1); + relaxed_data->data = US (relaxed_data+1); - for (p = data; *p; p++) - { - char c = *p; - if (c == '\r') - { - if (q > 0 && relaxed_data[q-1] == ' ') - q--; - } - else if (c == '\t' || c == ' ') - { - c = ' '; /* Turns WSP into SP */ - if (seen_wsp) - continue; - seen_wsp = TRUE; - } - else - seen_wsp = FALSE; - relaxed_data[q++] = c; + for (const uschar * p = orig_data->data, * r = p + orig_data->len; p < r; p++) + { + char c = *p; + if (c == '\r') + { + if (q > 0 && relaxed_data->data[q-1] == ' ') + q--; } - relaxed_data[q] = '\0'; - relaxed_len = q; + else if (c == '\t' || c == ' ') + { + c = ' '; /* Turns WSP into SP */ + if (seen_wsp) + continue; + seen_wsp = TRUE; + } + else + seen_wsp = FALSE; + relaxed_data->data[q++] = c; } - canon_data = relaxed_data; - canon_len = relaxed_len; + relaxed_data->data[q] = '\0'; + relaxed_data->len = q; } + canon_data = relaxed_data; + } - /* Make sure we don't exceed the to-be-signed body length */ - if ( sig->bodylength >= 0 - && sig->signed_body_bytes + (unsigned long)canon_len > sig->bodylength - ) - canon_len = sig->bodylength - sig->signed_body_bytes; - - if (canon_len > 0) - { - exim_sha_update(&sig->body_hash, CUS canon_data, canon_len); - sig->signed_body_bytes += canon_len; - DEBUG(D_acl) pdkim_quoteprint(canon_data, canon_len); - } +/* Make sure we don't exceed the to-be-signed body length */ +left = canon_data->len; +if ( b->bodylength >= 0 + && left > (unsigned long)b->bodylength - b->signed_body_bytes + ) + left = (unsigned long)b->bodylength - b->signed_body_bytes; - sig = sig->next; +if (left > 0) + { + exim_sha_update(&b->body_hash_ctx, CUS canon_data->data, left); + b->signed_body_bytes += left; + DEBUG(D_acl) pdkim_quoteprint(canon_data->data, left); } -if (relaxed_data) store_free(relaxed_data); -return PDKIM_OK; +return relaxed_data; } /* -------------------------------------------------------------------------- */ static void -pdkim_finish_bodyhash(pdkim_ctx *ctx) +pdkim_finish_bodyhash(pdkim_ctx * ctx) { -pdkim_signature *sig; +for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next) /* Finish hashes */ + { + DEBUG(D_acl) debug_printf("DKIM: finish bodyhash %d/%d/%ld len %ld\n", + b->hashtype, b->canon_method, b->bodylength, b->signed_body_bytes); + exim_sha_finish(&b->body_hash_ctx, &b->bh); + } /* Traverse all signatures */ -for (sig = ctx->sig; sig; sig = sig->next) - { /* Finish hashes */ - blob bh; - - exim_sha_finish(&sig->body_hash, &bh); +for (pdkim_signature * sig = ctx->sig; sig; sig = sig->next) + { + pdkim_bodyhash * b = sig->calc_body_hash; DEBUG(D_acl) { - debug_printf("PDKIM [%s] Body bytes hashed: %lu\n" - "PDKIM [%s] Body hash computed: ", - sig->domain, sig->signed_body_bytes, sig->domain); - pdkim_hexprint(CUS bh.data, bh.len); + debug_printf("DKIM [%s] Body bytes (%s) hashed: %lu\n" + "DKIM [%s] Body %s computed: ", + sig->domain, pdkim_canons[b->canon_method], b->signed_body_bytes, + sig->domain, pdkim_hashes[b->hashtype].dkim_hashname); + pdkim_hexprint(CUS b->bh.data, b->bh.len); } /* SIGNING -------------------------------------------------------------- */ if (ctx->flags & PDKIM_MODE_SIGN) { - sig->bodyhash = bh; - /* If bodylength limit is set, and we have received less bytes than the requested amount, effectively remove the limit tag. */ - if (sig->signed_body_bytes < sig->bodylength) + if (b->signed_body_bytes < sig->bodylength) sig->bodylength = -1; } - /* VERIFICATION --------------------------------------------------------- */ else - { - /* Compare bodyhash */ - if (memcmp(bh.data, sig->bodyhash.data, bh.len) == 0) + /* VERIFICATION --------------------------------------------------------- */ + /* Be careful that the header sig included a bodyash */ + + if (sig->bodyhash.data && sig->bodyhash.len == b->bh.len + && memcmp(b->bh.data, sig->bodyhash.data, b->bh.len) == 0) { - DEBUG(D_acl) debug_printf("PDKIM [%s] Body hash verified OK\n", sig->domain); + DEBUG(D_acl) debug_printf("DKIM [%s] Body hash compared OK\n", sig->domain); } else { DEBUG(D_acl) { - debug_printf("PDKIM [%s] Body hash signature from headers: ", sig->domain); - pdkim_hexprint(sig->bodyhash.data, - exim_sha_hashlen(&sig->body_hash)); - debug_printf("PDKIM [%s] Body hash did NOT verify\n", sig->domain); + debug_printf("DKIM [%s] Body hash signature from headers: ", sig->domain); + pdkim_hexprint(sig->bodyhash.data, sig->bodyhash.len); + debug_printf("DKIM [%s] Body hash did NOT verify\n", sig->domain); } sig->verify_status = PDKIM_VERIFY_FAIL; sig->verify_ext_status = PDKIM_VERIFY_FAIL_BODY; } - } } } -static int +static void pdkim_body_complete(pdkim_ctx * ctx) { -pdkim_signature * sig = ctx->sig; /*XXX assumes only one sig */ - /* In simple body mode, if any empty lines were buffered, replace with one. rfc 4871 3.4.3 */ /*XXX checking the signed-body-bytes is a gross hack; I think it indicates that all linebreaks should be buffered, including the one terminating a text line */ -if ( sig && sig->canon_body == PDKIM_CANON_SIMPLE - && sig->signed_body_bytes == 0 - && ctx->num_buffered_crlf > 0 - ) - pdkim_update_bodyhash(ctx, "\r\n", 2); +for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next) + if ( b->canon_method == PDKIM_CANON_SIMPLE + && b->signed_body_bytes == 0 + && b->num_buffered_blanklines > 0 + ) + (void) pdkim_update_ctx_bodyhash(b, &lineending, NULL); ctx->flags |= PDKIM_SEEN_EOD; ctx->linebuf_offset = 0; -return PDKIM_OK; } /* -------------------------------------------------------------------------- */ /* Call from pdkim_feed below for processing complete body lines */ +/* NOTE: the line is not NUL-terminated; but we have a count */ -static int -pdkim_bodyline_complete(pdkim_ctx *ctx) +static void +pdkim_bodyline_complete(pdkim_ctx * ctx) { -char *p = ctx->linebuf; -int n = ctx->linebuf_offset; -pdkim_signature *sig = ctx->sig; /*XXX assumes only one sig */ +blob line = {.data = ctx->linebuf, .len = ctx->linebuf_offset}; +blob * rnl = NULL; +blob * rline = NULL; /* Ignore extra data if we've seen the end-of-data marker */ -if (ctx->flags & PDKIM_SEEN_EOD) goto BAIL; +if (ctx->flags & PDKIM_SEEN_EOD) goto all_skip; /* We've always got one extra byte to stuff a zero ... */ -ctx->linebuf[ctx->linebuf_offset] = '\0'; +ctx->linebuf[line.len] = '\0'; /* Terminate on EOD marker */ if (ctx->flags & PDKIM_DOT_TERM) { - if ( memcmp(p, ".\r\n", 3) == 0) - return pdkim_body_complete(ctx); + if (memcmp(line.data, ".\r\n", 3) == 0) + { pdkim_body_complete(ctx); return; } /* Unstuff dots */ - if (memcmp(p, "..", 2) == 0) - { - p++; - n--; - } + if (memcmp(line.data, "..", 2) == 0) + { line.data++; line.len--; } } /* Empty lines need to be buffered until we find a non-empty line */ -if (memcmp(p, "\r\n", 2) == 0) +if (memcmp(line.data, "\r\n", 2) == 0) { - ctx->num_buffered_crlf++; - goto BAIL; + for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next) + b->num_buffered_blanklines++; + goto all_skip; } -if (sig && sig->canon_body == PDKIM_CANON_RELAXED) +/* Process line for each bodyhash separately */ +for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next) { - /* Lines with just spaces need to be buffered too */ - char *check = p; - while (memcmp(check, "\r\n", 2) != 0) + if (b->canon_method == PDKIM_CANON_RELAXED) { - char c = *check; + /* Lines with just spaces need to be buffered too */ + uschar * cp = line.data; + char c; + + while ((c = *cp)) + { + if (c == '\r' && cp[1] == '\n') break; + if (c != ' ' && c != '\t') goto hash_process; + cp++; + } - if (c != '\t' && c != ' ') - goto PROCESS; - check++; + b->num_buffered_blanklines++; + goto hash_skip; } - ctx->num_buffered_crlf++; - goto BAIL; -} +hash_process: + /* At this point, we have a non-empty line, so release the buffered ones. */ -PROCESS: -/* At this point, we have a non-empty line, so release the buffered ones. */ -while (ctx->num_buffered_crlf) - { - pdkim_update_bodyhash(ctx, "\r\n", 2); - ctx->num_buffered_crlf--; + while (b->num_buffered_blanklines) + { + rnl = pdkim_update_ctx_bodyhash(b, &lineending, rnl); + b->num_buffered_blanklines--; + } + + rline = pdkim_update_ctx_bodyhash(b, &line, rline); +hash_skip: ; } -pdkim_update_bodyhash(ctx, p, n); +if (rnl) store_free(rnl); +if (rline) store_free(rline); + +all_skip: -BAIL: ctx->linebuf_offset = 0; -return PDKIM_OK; +return; } @@ -932,68 +953,74 @@ return PDKIM_OK; #define DKIM_SIGNATURE_HEADERNAME "DKIM-Signature:" static int -pdkim_header_complete(pdkim_ctx *ctx) +pdkim_header_complete(pdkim_ctx * ctx) { -/* Special case: The last header can have an extra \r appended */ -if ( (ctx->cur_header_len > 1) && - (ctx->cur_header[(ctx->cur_header_len)-1] == '\r') ) - --ctx->cur_header_len; -ctx->cur_header[ctx->cur_header_len] = '\0'; +if ( (ctx->cur_header->ptr > 1) && + (ctx->cur_header->s[ctx->cur_header->ptr-1] == '\r') ) + --ctx->cur_header->ptr; +(void) string_from_gstring(ctx->cur_header); + +#ifdef EXPERIMENTAL_ARC +/* Feed the header line to ARC processing */ +(void) arc_header_feed(ctx->cur_header, !(ctx->flags & PDKIM_MODE_SIGN)); +#endif -ctx->num_headers++; -if (ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL; +if (++ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL; /* SIGNING -------------------------------------------------------------- */ if (ctx->flags & PDKIM_MODE_SIGN) - { - pdkim_signature *sig; - - for (sig = ctx->sig; sig; sig = sig->next) /* Traverse all signatures */ + for (pdkim_signature * sig = ctx->sig; sig; sig = sig->next) /* Traverse all signatures */ /* Add header to the signed headers list (in reverse order) */ - sig->headers = pdkim_prepend_stringlist(sig->headers, - ctx->cur_header); - } + sig->headers = pdkim_prepend_stringlist(sig->headers, ctx->cur_header->s); /* VERIFICATION ----------------------------------------------------------- */ /* DKIM-Signature: headers are added to the verification list */ else { - if (strncasecmp(CCS ctx->cur_header, +#ifdef notdef + DEBUG(D_acl) + { + debug_printf("DKIM >> raw hdr: "); + pdkim_quoteprint(CUS ctx->cur_header->s, ctx->cur_header->ptr); + } +#endif + if (strncasecmp(CCS ctx->cur_header->s, DKIM_SIGNATURE_HEADERNAME, Ustrlen(DKIM_SIGNATURE_HEADERNAME)) == 0) { - pdkim_signature *new_sig; + pdkim_signature * sig, * last_sig; + /* Create and chain new signature block. We could error-check for all + required tags here, but prefer to create the internal sig and expicitly + fail verification of it later. */ - /* Create and chain new signature block */ DEBUG(D_acl) debug_printf( - "PDKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"); + "DKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"); + + sig = pdkim_parse_sig_header(ctx, ctx->cur_header->s); - if ((new_sig = pdkim_parse_sig_header(ctx, ctx->cur_header))) + if (!(last_sig = ctx->sig)) + ctx->sig = sig; + else { - pdkim_signature *last_sig = ctx->sig; - if (!last_sig) - ctx->sig = new_sig; - else - { - while (last_sig->next) last_sig = last_sig->next; - last_sig->next = new_sig; - } + while (last_sig->next) last_sig = last_sig->next; + last_sig->next = sig; + } + + if (dkim_collect_input && --dkim_collect_input == 0) + { + ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header->s); + ctx->cur_header->s[ctx->cur_header->ptr = 0] = '\0'; + return PDKIM_ERR_EXCESS_SIGS; } - else - DEBUG(D_acl) debug_printf( - "Error while parsing signature header\n" - "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); } - /* every other header is stored for signature verification */ - else - ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header); + /* all headers are stored for signature verification */ + ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header->s); } BAIL: -*ctx->cur_header = '\0'; -ctx->cur_header_len = 0; /* leave buffer for reuse */ +ctx->cur_header->s[ctx->cur_header->ptr = 0] = '\0'; /* leave buffer for reuse */ return PDKIM_OK; } @@ -1003,64 +1030,72 @@ return PDKIM_OK; #define HEADER_BUFFER_FRAG_SIZE 256 DLLEXPORT int -pdkim_feed(pdkim_ctx *ctx, char *data, int len) +pdkim_feed(pdkim_ctx * ctx, uschar * data, int len) { -int p; - /* Alternate EOD signal, used in non-dotstuffing mode */ if (!data) pdkim_body_complete(ctx); -else for (p = 0; pflags & PDKIM_PAST_HDRS) { + if (c == '\n' && !(ctx->flags & PDKIM_SEEN_CR)) /* emulate the CR */ + { + ctx->linebuf[ctx->linebuf_offset++] = '\r'; + if (ctx->linebuf_offset == PDKIM_MAX_BODY_LINE_LEN-1) + return PDKIM_ERR_LONG_LINE; + } + /* Processing body byte */ ctx->linebuf[ctx->linebuf_offset++] = c; - if (c == '\n') + if (c == '\r') + ctx->flags |= PDKIM_SEEN_CR; + else if (c == '\n') { - int rc = pdkim_bodyline_complete(ctx); /* End of line */ - if (rc != PDKIM_OK) return rc; + ctx->flags &= ~PDKIM_SEEN_CR; + pdkim_bodyline_complete(ctx); } - if (ctx->linebuf_offset == (PDKIM_MAX_BODY_LINE_LEN-1)) + + if (ctx->linebuf_offset == PDKIM_MAX_BODY_LINE_LEN-1) return PDKIM_ERR_LONG_LINE; } else { /* Processing header byte */ - if (c != '\r') + if (c == '\r') + ctx->flags |= PDKIM_SEEN_CR; + else if (c == '\n') { - if (c == '\n') - { - if (ctx->flags & PDKIM_SEEN_LF) - { - int rc = pdkim_header_complete(ctx); /* Seen last header line */ - if (rc != PDKIM_OK) return rc; + if (!(ctx->flags & PDKIM_SEEN_CR)) /* emulate the CR */ + ctx->cur_header = string_catn(ctx->cur_header, CUS "\r", 1); - ctx->flags = ctx->flags & ~PDKIM_SEEN_LF | PDKIM_PAST_HDRS; - DEBUG(D_acl) debug_printf( - "PDKIM >> Body data for hash, canonicalized >>>>>>>>>>>>>>>>>>>>>>\n"); - continue; - } - else - ctx->flags |= PDKIM_SEEN_LF; - } - else if (ctx->flags & PDKIM_SEEN_LF) - { - if (!(c == '\t' || c == ' ')) - { - int rc = pdkim_header_complete(ctx); /* End of header */ - if (rc != PDKIM_OK) return rc; - } - ctx->flags &= ~PDKIM_SEEN_LF; + if (ctx->flags & PDKIM_SEEN_LF) /* Seen last header line */ + { + if ((rc = pdkim_header_complete(ctx)) != PDKIM_OK) + return rc; + + ctx->flags = (ctx->flags & ~(PDKIM_SEEN_LF|PDKIM_SEEN_CR)) | PDKIM_PAST_HDRS; + DEBUG(D_acl) debug_printf( + "DKIM >> Body data for hash, canonicalized >>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"); + continue; } + else + ctx->flags = (ctx->flags & ~PDKIM_SEEN_CR) | PDKIM_SEEN_LF; + } + else if (ctx->flags & PDKIM_SEEN_LF) + { + if (!(c == '\t' || c == ' ')) /* End of header */ + if ((rc = pdkim_header_complete(ctx)) != PDKIM_OK) + return rc; + ctx->flags &= ~PDKIM_SEEN_LF; } - if (ctx->cur_header_len < PDKIM_MAX_HEADER_LEN) - ctx->cur_header = string_catn(ctx->cur_header, &ctx->cur_header_size, - &ctx->cur_header_len, CUS &data[p], 1); + if (!ctx->cur_header || ctx->cur_header->ptr < PDKIM_MAX_HEADER_LEN) + ctx->cur_header = string_catn(ctx->cur_header, CUS &data[p], 1); } } return PDKIM_OK; @@ -1068,28 +1103,26 @@ return PDKIM_OK; -/* Extend a grwong header with a continuation-linebreak */ -static uschar * -pdkim_hdr_cont(uschar * str, int * size, int * ptr, int * col) +/* Extend a growing header with a continuation-linebreak */ +static gstring * +pdkim_hdr_cont(gstring * str, int * col) { *col = 1; -return string_catn(str, size, ptr, US"\r\n\t", 3); +return string_catn(str, US"\r\n\t", 3); } /* * RFC 5322 specifies that header line length SHOULD be no more than 78 - * lets make it so! * pdkim_headcat * - * returns uschar * (not nul-terminated) + * Returns gstring (not nul-terminated) appending to one supplied * * col: this int holds and receives column number (octets since last '\n') * str: partial string to append to - * size: current buffer size for str - * ptr: current tail-pointer for str - * pad: padding, split line or space after before or after eg: ";" + * pad: padding, split line or space after before or after eg: ";". + * Only the initial charater is used. * intro: - must join to payload eg "h=", usually the tag name * payload: eg base64 data - long data can be split arbitrarily. * @@ -1098,100 +1131,72 @@ return string_catn(str, size, ptr, US"\r\n\t", 3); * pairs and inside long values. it also always spaces or breaks after the * "pad" * - * no guarantees are made for output given out-of range input. like tag + * No guarantees are made for output given out-of range input. like tag * names longer than 78, or bogus col. Input is assumed to be free of line breaks. */ -static uschar * -pdkim_headcat(int * col, uschar * str, int * size, int * ptr, +static gstring * +pdkim_headcat(int * col, gstring * str, const uschar * pad, const uschar * intro, const uschar * payload) { -size_t l; - -if (pad) - { - l = Ustrlen(pad); - if (*col + l > 78) - str = pdkim_hdr_cont(str, size, ptr, col); - str = string_catn(str, size, ptr, pad, l); - *col += l; - } - -l = (pad?1:0) + (intro?Ustrlen(intro):0); - -if (*col + l > 78) - { /*can't fit intro - start a new line to make room.*/ - str = pdkim_hdr_cont(str, size, ptr, col); - l = intro?Ustrlen(intro):0; - } - -l += payload ? Ustrlen(payload):0 ; - -while (l>77) - { /* this fragment will not fit on a single line */ - if (pad) - { - str = string_catn(str, size, ptr, US" ", 1); - *col += 1; - pad = NULL; /* only want this once */ - l--; - } - - if (intro) - { - size_t sl = Ustrlen(intro); +int len, chomp, padded = 0; - str = string_catn(str, size, ptr, intro, sl); - *col += sl; - l -= sl; - intro = NULL; /* only want this once */ - } +/* If we can fit at least the pad at the end of current line, do it now. +Otherwise, wrap if there is a pad. */ - if (payload) +if (pad) + if (*col + 1 <= 78) { - size_t sl = Ustrlen(payload); - size_t chomp = *col+sl < 77 ? sl : 78-*col; - - str = string_catn(str, size, ptr, payload, chomp); - *col += chomp; - payload += chomp; - l -= chomp-1; + str = string_catn(str, pad, 1); + (*col)++; + pad = NULL; + padded = 1; } + else + str = pdkim_hdr_cont(str, col); - /* the while precondition tells us it didn't fit. */ - str = pdkim_hdr_cont(str, size, ptr, col); - } +/* Special case: if the whole addition does not fit at the end of the current +line, but could fit on a new line, wrap to give it its full, dedicated line. */ -if (*col + l > 78) +len = (pad ? 2 : padded) + + (intro ? Ustrlen(intro) : 0) + + (payload ? Ustrlen(payload) : 0); +if (len <= 77 && *col+len > 78) { - str = pdkim_hdr_cont(str, size, ptr, col); - pad = NULL; + str = pdkim_hdr_cont(str, col); + padded = 0; } +/* Either we already dealt with the pad or we know there is room */ + if (pad) { - str = string_catn(str, size, ptr, US" ", 1); - *col += 1; - pad = NULL; + str = string_catn(str, pad, 1); + str = string_catn(str, US" ", 1); + *col += 2; } - -if (intro) +else if (padded && *col < 78) { - size_t sl = Ustrlen(intro); - - str = string_catn(str, size, ptr, intro, sl); - *col += sl; - l -= sl; - intro = NULL; + str = string_catn(str, US" ", 1); + (*col)++; } -if (payload) - { - size_t sl = Ustrlen(payload); +/* Call recursively with intro as payload: it gets the same, special treatment +(that is, not split if < 78). */ - str = string_catn(str, size, ptr, payload, sl); - *col += sl; - } +if (intro) + str = pdkim_headcat(col, str, NULL, NULL, intro); + +if (payload) + for (len = Ustrlen(payload); len; len -= chomp) + { + if (*col >= 78) + str = pdkim_hdr_cont(str, col); + chomp = *col+len > 78 ? 78 - *col : len; + str = string_catn(str, payload, chomp); + *col += chomp; + payload += chomp; + } return str; } @@ -1199,37 +1204,31 @@ return str; /* -------------------------------------------------------------------------- */ +/* Signing: create signature header +*/ static uschar * -pdkim_create_header(pdkim_signature *sig, BOOL final) +pdkim_create_header(pdkim_signature * sig, BOOL final) { uschar * base64_bh; uschar * base64_b; int col = 0; -uschar * hdr; int hdr_size = 0, hdr_len = 0; -uschar * canon_all; int can_size = 0, can_len = 0; +gstring * hdr; +gstring * canon_all; -canon_all = string_cat (NULL, &can_size, &can_len, - pdkim_canons[sig->canon_headers]); -canon_all = string_catn(canon_all, &can_size, &can_len, US"/", 1); -canon_all = string_cat (canon_all, &can_size, &can_len, - pdkim_canons[sig->canon_body]); -canon_all[can_len] = '\0'; +canon_all = string_cat (NULL, pdkim_canons[sig->canon_headers]); +canon_all = string_catn(canon_all, US"/", 1); +canon_all = string_cat (canon_all, pdkim_canons[sig->canon_body]); +(void) string_from_gstring(canon_all); -hdr = string_cat(NULL, &hdr_size, &hdr_len, - US"DKIM-Signature: v="PDKIM_SIGNATURE_VERSION); -col = hdr_len; +hdr = string_cat(NULL, US"DKIM-Signature: v="PDKIM_SIGNATURE_VERSION); +col = hdr->ptr; /* Required and static bits */ -hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"a=", - pdkim_algos[sig->algo]); -hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"q=", - pdkim_querymethods[sig->querymethod]); -hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"c=", - canon_all); -hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"d=", - sig->domain); -hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"s=", - sig->selector); +hdr = pdkim_headcat(&col, hdr, US";", US"a=", dkim_sig_to_a_tag(sig)); +hdr = pdkim_headcat(&col, hdr, US";", US"q=", pdkim_querymethods[sig->querymethod]); +hdr = pdkim_headcat(&col, hdr, US";", US"c=", canon_all->s); +hdr = pdkim_headcat(&col, hdr, US";", US"d=", sig->domain); +hdr = pdkim_headcat(&col, hdr, US";", US"s=", sig->selector); /* list of header names can be split between items. */ { @@ -1244,9 +1243,9 @@ hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"s=", if (c) *c ='\0'; if (!i) - hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, NULL, NULL, US":"); + hdr = pdkim_headcat(&col, hdr, NULL, NULL, US":"); - hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, s, i, n); + hdr = pdkim_headcat(&col, hdr, s, i, n); if (!c) break; @@ -1257,19 +1256,19 @@ hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"s=", } } -base64_bh = pdkim_encode_base64(&sig->bodyhash); -hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"bh=", base64_bh); +base64_bh = pdkim_encode_base64(&sig->calc_body_hash->bh); +hdr = pdkim_headcat(&col, hdr, US";", US"bh=", base64_bh); /* Optional bits */ if (sig->identity) - hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"i=", sig->identity); + hdr = pdkim_headcat(&col, hdr, US";", US"i=", sig->identity); if (sig->created > 0) { uschar minibuf[20]; snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->created); - hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"t=", minibuf); + hdr = pdkim_headcat(&col, hdr, US";", US"t=", minibuf); } if (sig->expires > 0) @@ -1277,7 +1276,7 @@ if (sig->expires > 0) uschar minibuf[20]; snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->expires); - hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"x=", minibuf); + hdr = pdkim_headcat(&col, hdr, US";", US"x=", minibuf); } if (sig->bodylength >= 0) @@ -1285,38 +1284,69 @@ if (sig->bodylength >= 0) uschar minibuf[20]; snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->bodylength); - hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"l=", minibuf); + hdr = pdkim_headcat(&col, hdr, US";", US"l=", minibuf); } /* Preliminary or final version? */ -base64_b = final ? pdkim_encode_base64(&sig->sigdata) : US""; -hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"b=", base64_b); +if (final) + { + base64_b = pdkim_encode_base64(&sig->sighash); + hdr = pdkim_headcat(&col, hdr, US";", US"b=", base64_b); -/* add trailing semicolon: I'm not sure if this is actually needed */ -hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, NULL, US";", US""); + /* add trailing semicolon: I'm not sure if this is actually needed */ + hdr = pdkim_headcat(&col, hdr, NULL, US";", US""); + } +else + { + /* To satisfy the rule "all surrounding whitespace [...] deleted" + ( RFC 6376 section 3.7 ) we ensure there is no whitespace here. Otherwise + the headcat routine could insert a linebreak which the relaxer would reduce + to a single space preceding the terminating semicolon, resulting in an + incorrect header-hash. */ + hdr = pdkim_headcat(&col, hdr, US";", US"b=;", US""); + } -hdr[hdr_len] = '\0'; -return hdr; +return string_from_gstring(hdr); } /* -------------------------------------------------------------------------- */ +/* According to draft-ietf-dcrup-dkim-crypto-07 "keys are 256 bits" (referring +to DNS, hence the pubkey). Check for more than 32 bytes; if so assume the +alternate possible representation (still) being discussed: a +SubjectPublickeyInfo wrapped key - and drop all but the trailing 32-bytes (it +should be a DER, with exactly 12 leading bytes - but we could accept a BER also, +which could be any size). We still rely on the crypto library for checking for +undersize. + +When the RFC is published this should be re-addressed. */ + +static void +check_bare_ed25519_pubkey(pdkim_pubkey * p) +{ +int excess = p->key.len - 32; +if (excess > 0) + { + DEBUG(D_acl) + debug_printf("DKIM: unexpected pubkey len %lu\n", (unsigned long) p->key.len); + p->key.data += excess; p->key.len = 32; + } +} + + static pdkim_pubkey * -pdkim_key_from_dns(pdkim_ctx * ctx, pdkim_signature * sig, ev_ctx * vctx) +pdkim_key_from_dns(pdkim_ctx * ctx, pdkim_signature * sig, ev_ctx * vctx, + const uschar ** errstr) { uschar * dns_txt_name, * dns_txt_reply; pdkim_pubkey * p; -const uschar * errstr; /* Fetch public key for signing domain, from DNS */ dns_txt_name = string_sprintf("%s._domainkey.%s.", sig->selector, sig->domain); -dns_txt_reply = store_get(PDKIM_DNS_TXT_MAX_RECLEN); -memset(dns_txt_reply, 0, PDKIM_DNS_TXT_MAX_RECLEN); - -if ( ctx->dns_txt_callback(CS dns_txt_name, CS dns_txt_reply) != PDKIM_OK +if ( !(dns_txt_reply = ctx->dns_txt_callback(dns_txt_name)) || dns_txt_reply[0] == '\0' ) { @@ -1328,12 +1358,14 @@ if ( ctx->dns_txt_callback(CS dns_txt_name, CS dns_txt_reply) != PDKIM_OK DEBUG(D_acl) { debug_printf( - "PDKIM >> Parsing public key record >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n" - " Raw record: "); + "DKIM >> Parsing public key record >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n" + " %s\n" + " Raw record: ", + dns_txt_name); pdkim_quoteprint(CUS dns_txt_reply, Ustrlen(dns_txt_reply)); } -if ( !(p = pdkim_parse_pubkey_record(ctx, CUS dns_txt_reply)) +if ( !(p = pdkim_parse_pubkey_record(CUS dns_txt_reply)) || (Ustrcmp(p->srvtype, "*") != 0 && Ustrcmp(p->srvtype, "email") != 0) ) { @@ -1347,66 +1379,201 @@ if ( !(p = pdkim_parse_pubkey_record(ctx, CUS dns_txt_reply)) else debug_printf(" Error while parsing public key record\n"); debug_printf( - "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); } return NULL; } DEBUG(D_acl) debug_printf( - "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); /* Import public key */ -if ((errstr = exim_rsa_verify_init(&p->key, vctx))) + +/* Normally we use the signature a= tag to tell us the pubkey format. +When signing under debug we do a test-import of the pubkey, and at that +time we do not have a signature so we must interpret the pubkey k= tag +instead. Assume writing on the sig is ok in that case. */ + +if (sig->keytype < 0) + if ((sig->keytype = pdkim_keyname_to_keytype(p->keytype)) < 0) + { + DEBUG(D_acl) debug_printf("verify_init: unhandled keytype %s\n", p->keytype); + sig->verify_status = PDKIM_VERIFY_INVALID; + sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_IMPORT; + return NULL; + } + +if (sig->keytype == KEYTYPE_ED25519) + check_bare_ed25519_pubkey(p); + +if ((*errstr = exim_dkim_verify_init(&p->key, + sig->keytype == KEYTYPE_ED25519 ? KEYFMT_ED25519_BARE : KEYFMT_DER, + vctx, &sig->keybits))) { - DEBUG(D_acl) debug_printf("verify_init: %s\n", errstr); + DEBUG(D_acl) debug_printf("verify_init: %s\n", *errstr); sig->verify_status = PDKIM_VERIFY_INVALID; sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_IMPORT; return NULL; } +vctx->keytype = sig->keytype; return p; } +/* -------------------------------------------------------------------------- */ +/* Sort and filter the sigs developed from the message */ + +static pdkim_signature * +sort_sig_methods(pdkim_signature * siglist) +{ +pdkim_signature * yield, ** ss; +const uschar * prefs; +uschar * ele; +int sep; + +if (!siglist) return NULL; + +/* first select in order of hashtypes */ +DEBUG(D_acl) debug_printf("DKIM: dkim_verify_hashes '%s'\n", dkim_verify_hashes); +for (prefs = dkim_verify_hashes, sep = 0, yield = NULL, ss = &yield; + ele = string_nextinlist(&prefs, &sep, NULL, 0); ) + { + int i = pdkim_hashname_to_hashtype(CUS ele, 0); + for (pdkim_signature * s = siglist, * next, ** prev = &siglist; s; + s = next) + { + next = s->next; + if (s->hashtype == i) + { *prev = next; s->next = NULL; *ss = s; ss = &s->next; } + else + prev = &s->next; + } + } + +/* then in order of keytypes */ +siglist = yield; +DEBUG(D_acl) debug_printf("DKIM: dkim_verify_keytypes '%s'\n", dkim_verify_keytypes); +for (prefs = dkim_verify_keytypes, sep = 0, yield = NULL, ss = &yield; + ele = string_nextinlist(&prefs, &sep, NULL, 0); ) + { + int i = pdkim_keyname_to_keytype(CUS ele); + for (pdkim_signature * s = siglist, * next, ** prev = &siglist; s; + s = next) + { + next = s->next; + if (s->keytype == i) + { *prev = next; s->next = NULL; *ss = s; ss = &s->next; } + else + prev = &s->next; + } + } + +DEBUG(D_acl) for (pdkim_signature * s = yield; s; s = s->next) + debug_printf(" retain d=%s s=%s a=%s\n", + s->domain, s->selector, dkim_sig_to_a_tag(s)); +return yield; +} + + /* -------------------------------------------------------------------------- */ DLLEXPORT int -pdkim_feed_finish(pdkim_ctx *ctx, pdkim_signature **return_signatures) +pdkim_feed_finish(pdkim_ctx * ctx, pdkim_signature ** return_signatures, + const uschar ** err) { -pdkim_signature *sig = ctx->sig; +BOOL verify_pass = FALSE; /* Check if we must still flush a (partial) header. If that is the case, the message has no body, and we must compute a body hash out of '' */ -if (ctx->cur_header && ctx->cur_header_len) +if (ctx->cur_header && ctx->cur_header->ptr > 0) { - int rc = pdkim_header_complete(ctx); - if (rc != PDKIM_OK) return rc; - pdkim_update_bodyhash(ctx, "\r\n", 2); + blob * rnl = NULL; + int rc; + + if ((rc = pdkim_header_complete(ctx)) != PDKIM_OK) + return rc; + + for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next) + rnl = pdkim_update_ctx_bodyhash(b, &lineending, rnl); + if (rnl) store_free(rnl); } else DEBUG(D_acl) debug_printf( - "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + +/* Build (and/or evaluate) body hash. Do this even if no DKIM sigs, in case we +have a hash to do for ARC. */ -/* Build (and/or evaluate) body hash */ pdkim_finish_bodyhash(ctx); -while (sig) +/* Sort and filter the recived signatures */ + +if (!(ctx->flags & PDKIM_MODE_SIGN)) + ctx->sig = sort_sig_methods(ctx->sig); + +if (!ctx->sig) + { + DEBUG(D_acl) debug_printf("DKIM: no signatures\n"); + *return_signatures = NULL; + return PDKIM_OK; + } + +for (pdkim_signature * sig = ctx->sig; sig; sig = sig->next) { - BOOL is_sha1 = sig->algo == PDKIM_ALGO_RSA_SHA1; hctx hhash_ctx; uschar * sig_hdr = US""; blob hhash; - blob hdata; - int hdata_alloc = 0; + gstring * hdata = NULL; + es_ctx sctx; - hdata.data = NULL; - hdata.len = 0; + if ( !(ctx->flags & PDKIM_MODE_SIGN) + && sig->verify_status == PDKIM_VERIFY_FAIL) + { + DEBUG(D_acl) + debug_printf("DKIM: [%s] abandoning this signature\n", sig->domain); + continue; + } + + /*XXX The hash of the headers is needed for GCrypt (for which we can do RSA + signing only, as it happens) and for either GnuTLS and OpenSSL when we are + signing with EC (specifically, Ed25519). The former is because the GCrypt + signing operation is pure (does not do its own hash) so we must hash. The + latter is because we (stupidly, but this is what the IETF draft is saying) + must hash with the declared hash method, then pass the result to the library + hash-and-sign routine (because that's all the libraries are providing. And + we're stuck with whatever that hidden hash method is, too). We may as well + do this hash incrementally. + We don't need the hash we're calculating here for the GnuTLS and OpenSSL + cases of RSA signing, since those library routines can do hash-and-sign. + + Some time in the future we could easily avoid doing the hash here for those + cases (which will be common for a long while. We could also change from + the current copy-all-the-headers-into-one-block, then call the hash-and-sign + implementation - to a proper incremental one. Unfortunately, GnuTLS just + cannot do incremental - either signing or verification. Unsure about GCrypt. + */ + + /*XXX The header hash is also used (so far) by the verify operation */ + + if (!exim_sha_init(&hhash_ctx, pdkim_hashes[sig->hashtype].exim_hashmethod)) + { + log_write(0, LOG_MAIN|LOG_PANIC, + "DKIM: hash setup error, possibly nonhandled hashtype"); + break; + } - exim_sha_init(&hhash_ctx, is_sha1 ? HASH_SHA1 : HASH_SHA256); + if (ctx->flags & PDKIM_MODE_SIGN) + DEBUG(D_acl) debug_printf( + "DKIM >> Headers to be signed: >>>>>>>>>>>>\n" + " %s\n", + sig->sign_headers); DEBUG(D_acl) debug_printf( - "PDKIM >> Header data for hash, canonicalized, in sequence >>>>>>>>>>>>>>\n"); + "DKIM >> Header data for hash, canonicalized (%-7s), in sequence >>\n", + pdkim_canons[sig->canon_headers]); + /* SIGNING ---------------------------------------------------------------- */ /* When signing, walk through our header list and add them to the hash. As we @@ -1416,49 +1583,57 @@ while (sig) if (ctx->flags & PDKIM_MODE_SIGN) { - uschar * headernames = NULL; /* Collected signed header names */ - int hs = 0, hl = 0; - pdkim_stringlist *p; + gstring * g = NULL; const uschar * l; uschar * s; int sep = 0; - for (p = sig->headers; p; p = p->next) - if (header_name_match(p->value, sig->sign_headers) == PDKIM_OK) + /* Import private key, including the keytype which we need for building + the signature header */ + + if ((*err = exim_dkim_signing_init(CUS sig->privkey, &sctx))) + { + log_write(0, LOG_MAIN|LOG_PANIC, "signing_init: %s", *err); + return PDKIM_ERR_RSA_PRIVKEY; + } + sig->keytype = sctx.keytype; + + sig->headernames = NULL; /* Collected signed header names */ + for (pdkim_stringlist * p = sig->headers; p; p = p->next) + { + uschar * rh = p->value; + + if (header_name_match(rh, sig->sign_headers) == PDKIM_OK) { - uschar * rh; /* Collect header names (Note: colon presence is guaranteed here) */ - uschar * q = Ustrchr(p->value, ':'); - - headernames = string_catn(headernames, &hs, &hl, - p->value, (q - US p->value) + (p->next ? 1 : 0)); + g = string_append_listele_n(g, ':', rh, Ustrchr(rh, ':') - rh); - rh = sig->canon_headers == PDKIM_CANON_RELAXED - ? pdkim_relax_header(p->value, 1) /* cook header for relaxed canon */ - : string_copy(CUS p->value); /* just copy it for simple canon */ + if (sig->canon_headers == PDKIM_CANON_RELAXED) + rh = pdkim_relax_header(rh, TRUE); /* cook header for relaxed canon */ /* Feed header to the hash algorithm */ exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh)); /* Remember headers block for signing (when the library cannot do incremental) */ - (void) exim_rsa_data_append(&hdata, &hdata_alloc, rh); + /*XXX we could avoid doing this for all but the GnuTLS/RSA case */ + hdata = exim_dkim_data_append(hdata, rh); DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh)); } + } + + /* Any headers we wanted to sign but were not present must also be listed. + Ignore elements that have been ticked-off or are marked as never-oversign. */ l = sig->sign_headers; while((s = string_nextinlist(&l, &sep, NULL, 0))) - if (*s != '_') - { /*SSS string_append_listele() */ - if (hl > 0 && headernames[hl-1] != ':') - headernames = string_catn(headernames, &hs, &hl, US":", 1); - - headernames = string_cat(headernames, &hs, &hl, s); - } - headernames[hl] = '\0'; - - /* Copy headernames to signature struct */ - sig->headernames = headernames; + { + if (*s == '+') /* skip oversigning marker */ + s++; + if (*s != '_' && *s != '=') + g = string_append_listele(g, ':', s); + } + sig->headernames = string_from_gstring(g); /* Create signature header with b= omitted */ sig_hdr = pdkim_create_header(sig, FALSE); @@ -1471,12 +1646,11 @@ while (sig) { uschar * p = sig->headernames; uschar * q; - pdkim_stringlist * hdrs; if (p) { /* clear tags */ - for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next) + for (pdkim_stringlist * hdrs = ctx->headers; hdrs; hdrs = hdrs->next) hdrs->tag = 0; p = string_copy(p); @@ -1486,7 +1660,7 @@ while (sig) *q = '\0'; /*XXX walk the list of headers in same order as received. */ - for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next) + for (pdkim_stringlist * hdrs = ctx->headers; hdrs; hdrs = hdrs->next) if ( hdrs->tag == 0 && strncasecmp(CCS hdrs->value, CCS p, Ustrlen(p)) == 0 && (hdrs->value)[Ustrlen(p)] == ':' @@ -1495,7 +1669,7 @@ while (sig) /* cook header for relaxed canon, or just copy it for simple */ uschar * rh = sig->canon_headers == PDKIM_CANON_RELAXED - ? pdkim_relax_header(hdrs->value, 1) + ? pdkim_relax_header(hdrs->value, TRUE) : string_copy(CUS hdrs->value); /* Feed header to the hash algorithm */ @@ -1515,19 +1689,28 @@ while (sig) } DEBUG(D_acl) debug_printf( - "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + + DEBUG(D_acl) + { + debug_printf( + "DKIM >> Signed DKIM-Signature header, pre-canonicalized >>>>>>>>>>>>>\n"); + pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr)); + debug_printf( + "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + } /* Relax header if necessary */ if (sig->canon_headers == PDKIM_CANON_RELAXED) - sig_hdr = pdkim_relax_header(sig_hdr, 0); + sig_hdr = pdkim_relax_header(sig_hdr, FALSE); DEBUG(D_acl) { - debug_printf( - "PDKIM >> Signed DKIM-Signature header, canonicalized >>>>>>>>>>>>>>>>>\n"); + debug_printf("DKIM >> Signed DKIM-Signature header, canonicalized (%-7s) >>>>>>>\n", + pdkim_canons[sig->canon_headers]); pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr)); debug_printf( - "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); } /* Finalize header hash */ @@ -1536,45 +1719,48 @@ while (sig) DEBUG(D_acl) { - debug_printf("PDKIM [%s] Header hash computed: ", sig->domain); + debug_printf("DKIM [%s] Header %s computed: ", + sig->domain, pdkim_hashes[sig->hashtype].dkim_hashname); pdkim_hexprint(hhash.data, hhash.len); } - /* Remember headers block for signing (when the library cannot do incremental) */ + /* Remember headers block for signing (when the signing library cannot do + incremental) */ if (ctx->flags & PDKIM_MODE_SIGN) - (void) exim_rsa_data_append(&hdata, &hdata_alloc, US sig_hdr); + hdata = exim_dkim_data_append(hdata, US sig_hdr); /* SIGNING ---------------------------------------------------------------- */ if (ctx->flags & PDKIM_MODE_SIGN) { - es_ctx sctx; - const uschar * errstr; - - /* Import private key */ - if ((errstr = exim_rsa_signing_init(US sig->rsa_privkey, &sctx))) - { - DEBUG(D_acl) debug_printf("signing_init: %s\n", errstr); - return PDKIM_ERR_RSA_PRIVKEY; - } + hashmethod hm = sig->keytype == KEYTYPE_ED25519 +#if defined(SIGN_OPENSSL) + ? HASH_NULL +#else + ? HASH_SHA2_512 +#endif + : pdkim_hashes[sig->hashtype].exim_hashmethod; - /* Do signing. With OpenSSL we are signing the hash of headers just - calculated, with GnuTLS we have to sign an entire block of headers - (due to available interfaces) and it recalculates the hash internally. */ +#ifdef SIGN_HAVE_ED25519 + /* For GCrypt, and for EC, we pass the hash-of-headers to the signing + routine. For anything else we just pass the headers. */ -#if defined(RSA_OPENSSL) || defined(RSA_GCRYPT) - hdata = hhash; + if (sig->keytype != KEYTYPE_ED25519) #endif + { + hhash.data = hdata->s; + hhash.len = hdata->ptr; + } - if ((errstr = exim_rsa_sign(&sctx, is_sha1, &hdata, &sig->sigdata))) + if ((*err = exim_dkim_sign(&sctx, hm, &hhash, &sig->sighash))) { - DEBUG(D_acl) debug_printf("signing: %s\n", errstr); + log_write(0, LOG_MAIN|LOG_PANIC, "signing: %s", *err); return PDKIM_ERR_RSA_SIGNING; } DEBUG(D_acl) { - debug_printf( "PDKIM [%s] b computed: ", sig->domain); - pdkim_hexprint(sig->sigdata.data, sig->sigdata.len); + debug_printf( "DKIM [%s] b computed: ", sig->domain); + pdkim_hexprint(sig->sighash.data, sig->sighash.len); } sig->signature_header = pdkim_create_header(sig, TRUE); @@ -1584,16 +1770,16 @@ while (sig) else { ev_ctx vctx; - const uschar * errstr; - pdkim_pubkey * p; + hashmethod hm; /* Make sure we have all required signature tags */ if (!( sig->domain && *sig->domain && sig->selector && *sig->selector && sig->headernames && *sig->headernames && sig->bodyhash.data - && sig->sigdata.data - && sig->algo > -1 + && sig->sighash.data + && sig->keytype >= 0 + && sig->hashtype >= 0 && sig->version ) ) { @@ -1601,8 +1787,16 @@ while (sig) sig->verify_ext_status = PDKIM_VERIFY_INVALID_SIGNATURE_ERROR; DEBUG(D_acl) debug_printf( - " Error in DKIM-Signature header: tags missing or invalid\n" - "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + " Error in DKIM-Signature header: tags missing or invalid (%s)\n" + "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n", + !(sig->domain && *sig->domain) ? "d=" + : !(sig->selector && *sig->selector) ? "s=" + : !(sig->headernames && *sig->headernames) ? "h=" + : !sig->bodyhash.data ? "bh=" + : !sig->sighash.data ? "b=" + : sig->keytype < 0 || sig->hashtype < 0 ? "a=" + : "v=" + ); goto NEXT_VERIFY; } @@ -1614,33 +1808,92 @@ while (sig) DEBUG(D_acl) debug_printf( " Error in DKIM-Signature header: unsupported DKIM version\n" - "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + "DKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); goto NEXT_VERIFY; } - if (!(sig->pubkey = pdkim_key_from_dns(ctx, sig, &vctx))) + DEBUG(D_acl) + { + debug_printf( "DKIM [%s] b from mail: ", sig->domain); + pdkim_hexprint(sig->sighash.data, sig->sighash.len); + } + + if (!(sig->pubkey = pdkim_key_from_dns(ctx, sig, &vctx, err))) + { + log_write(0, LOG_MAIN, "DKIM: %s%s %s%s [failed key import]", + sig->domain ? "d=" : "", sig->domain ? sig->domain : US"", + sig->selector ? "s=" : "", sig->selector ? sig->selector : US""); goto NEXT_VERIFY; + } + + /* If the pubkey limits to a list of specific hashes, ignore sigs that + do not have the hash part of the sig algorithm matching */ + + if (sig->pubkey->hashes) + { + const uschar * list = sig->pubkey->hashes, * ele; + int sep = ':'; + while ((ele = string_nextinlist(&list, &sep, NULL, 0))) + if (Ustrcmp(ele, pdkim_hashes[sig->hashtype].dkim_hashname) == 0) break; + if (!ele) + { + DEBUG(D_acl) debug_printf("pubkey h=%s vs. sig a=%s_%s\n", + sig->pubkey->hashes, + pdkim_keytypes[sig->keytype], + pdkim_hashes[sig->hashtype].dkim_hashname); + sig->verify_status = PDKIM_VERIFY_FAIL; + sig->verify_ext_status = PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH; + goto NEXT_VERIFY; + } + } + + hm = sig->keytype == KEYTYPE_ED25519 +#if defined(SIGN_OPENSSL) + ? HASH_NULL +#else + ? HASH_SHA2_512 +#endif + : pdkim_hashes[sig->hashtype].exim_hashmethod; /* Check the signature */ - if ((errstr = exim_rsa_verify(&vctx, is_sha1, &hhash, &sig->sigdata))) + + if ((*err = exim_dkim_verify(&vctx, hm, &hhash, &sig->sighash))) { - DEBUG(D_acl) debug_printf("headers verify: %s\n", errstr); + DEBUG(D_acl) debug_printf("headers verify: %s\n", *err); sig->verify_status = PDKIM_VERIFY_FAIL; sig->verify_ext_status = PDKIM_VERIFY_FAIL_MESSAGE; goto NEXT_VERIFY; } + if (*dkim_verify_min_keysizes) + { + unsigned minbits; + uschar * ss = expand_getkeyed(US pdkim_keytypes[sig->keytype], + dkim_verify_min_keysizes); + if (ss && (minbits = atoi(CS ss)) > sig->keybits) + { + DEBUG(D_acl) debug_printf("Key too short: Actual: %s %u Minima '%s'\n", + pdkim_keytypes[sig->keytype], sig->keybits, dkim_verify_min_keysizes); + sig->verify_status = PDKIM_VERIFY_FAIL; + sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE; + } + } /* We have a winner! (if bodyhash was correct earlier) */ if (sig->verify_status == PDKIM_VERIFY_NONE) + { sig->verify_status = PDKIM_VERIFY_PASS; + verify_pass = TRUE; + if (dkim_verify_minimal) break; + } NEXT_VERIFY: DEBUG(D_acl) { - debug_printf("PDKIM [%s] signature status: %s", - sig->domain, pdkim_verify_status_str(sig->verify_status)); + debug_printf("DKIM [%s] %s signature status: %s", + sig->domain, dkim_sig_to_a_tag(sig), + pdkim_verify_status_str(sig->verify_status)); if (sig->verify_ext_status > 0) debug_printf(" (%s)\n", pdkim_verify_ext_status_str(sig->verify_ext_status)); @@ -1648,31 +1901,32 @@ NEXT_VERIFY: debug_printf("\n"); } } - - sig = sig->next; } /* If requested, set return pointer to signature(s) */ if (return_signatures) *return_signatures = ctx->sig; -return PDKIM_OK; +return ctx->flags & PDKIM_MODE_SIGN || verify_pass + ? PDKIM_OK : PDKIM_FAIL; } /* -------------------------------------------------------------------------- */ DLLEXPORT pdkim_ctx * -pdkim_init_verify(int(*dns_txt_callback)(char *, char *), BOOL dot_stuffing) +pdkim_init_verify(uschar * (*dns_txt_callback)(const uschar *), BOOL dot_stuffing) { pdkim_ctx * ctx; -ctx = store_get(sizeof(pdkim_ctx)); +ctx = store_get(sizeof(pdkim_ctx), FALSE); memset(ctx, 0, sizeof(pdkim_ctx)); if (dot_stuffing) ctx->flags = PDKIM_DOT_TERM; -ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN); +/* The line-buffer is for message data, hence tainted */ +ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN, TRUE); ctx->dns_txt_callback = dns_txt_callback; +ctx->cur_header = string_get_tainted(36, TRUE); return ctx; } @@ -1680,66 +1934,65 @@ return ctx; /* -------------------------------------------------------------------------- */ -DLLEXPORT pdkim_ctx * -pdkim_init_sign(char * domain, char * selector, char * rsa_privkey, int algo, - BOOL dot_stuffed, int(*dns_txt_callback)(char *, char *)) +DLLEXPORT pdkim_signature * +pdkim_init_sign(pdkim_ctx * ctx, + uschar * domain, uschar * selector, uschar * privkey, + uschar * hashname, const uschar ** errstr) { -pdkim_ctx * ctx; +int hashtype; pdkim_signature * sig; -if (!domain || !selector || !rsa_privkey) +if (!domain || !selector || !privkey) return NULL; -ctx = store_get(sizeof(pdkim_ctx) + PDKIM_MAX_BODY_LINE_LEN + sizeof(pdkim_signature)); -memset(ctx, 0, sizeof(pdkim_ctx)); - -ctx->flags = dot_stuffed ? PDKIM_MODE_SIGN | PDKIM_DOT_TERM : PDKIM_MODE_SIGN; -ctx->linebuf = CS (ctx+1); - -DEBUG(D_acl) ctx->dns_txt_callback = dns_txt_callback; +/* Allocate & init one signature struct */ -sig = (pdkim_signature *)(ctx->linebuf + PDKIM_MAX_BODY_LINE_LEN); +sig = store_get(sizeof(pdkim_signature), FALSE); memset(sig, 0, sizeof(pdkim_signature)); sig->bodylength = -1; -ctx->sig = sig; sig->domain = string_copy(US domain); sig->selector = string_copy(US selector); -sig->rsa_privkey = string_copy(US rsa_privkey); -sig->algo = algo; +sig->privkey = string_copy(US privkey); +sig->keytype = -1; -exim_sha_init(&sig->body_hash, algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256); +for (hashtype = 0; hashtype < nelem(pdkim_hashes); hashtype++) + if (Ustrcmp(hashname, pdkim_hashes[hashtype].dkim_hashname) == 0) + { sig->hashtype = hashtype; break; } +if (hashtype >= nelem(pdkim_hashes)) + { + log_write(0, LOG_MAIN|LOG_PANIC, + "DKIM: unrecognised hashname '%s'", hashname); + return NULL; + } DEBUG(D_acl) { pdkim_signature s = *sig; ev_ctx vctx; - debug_printf("PDKIM (checking verify key)<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); - if (!pdkim_key_from_dns(ctx, &s, &vctx)) + debug_printf("DKIM (checking verify key)>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"); + if (!pdkim_key_from_dns(ctx, &s, &vctx, errstr)) debug_printf("WARNING: bad dkim key in dns\n"); - debug_printf("PDKIM (finished checking verify key)<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); + debug_printf("DKIM (finished checking verify key)<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); } - -return ctx; +return sig; } /* -------------------------------------------------------------------------- */ -DLLEXPORT int -pdkim_set_optional(pdkim_ctx *ctx, - char *sign_headers, - char *identity, +DLLEXPORT void +pdkim_set_optional(pdkim_signature * sig, + char * sign_headers, + char * identity, int canon_headers, int canon_body, long bodylength, unsigned long created, unsigned long expires) { -pdkim_signature * sig = ctx->sig; - if (identity) sig->identity = string_copy(US identity); @@ -1752,14 +2005,90 @@ sig->bodylength = bodylength; sig->created = created; sig->expires = expires; -return PDKIM_OK; +return; +} + + + +/* Set up a blob for calculating the bodyhash according to the +given needs. Use an existing one if possible, or create a new one. + +Return: hashblob pointer, or NULL on error +*/ +pdkim_bodyhash * +pdkim_set_bodyhash(pdkim_ctx * ctx, int hashtype, int canon_method, + long bodylength) +{ +pdkim_bodyhash * b; + +if (hashtype == -1 || canon_method == -1) return NULL; + +for (b = ctx->bodyhash; b; b = b->next) + if ( hashtype == b->hashtype + && canon_method == b->canon_method + && bodylength == b->bodylength) + { + DEBUG(D_receive) debug_printf("DKIM: using existing bodyhash %d/%d/%ld\n", + hashtype, canon_method, bodylength); + return b; + } + +DEBUG(D_receive) debug_printf("DKIM: new bodyhash %d/%d/%ld\n", + hashtype, canon_method, bodylength); +b = store_get(sizeof(pdkim_bodyhash), FALSE); +b->next = ctx->bodyhash; +b->hashtype = hashtype; +b->canon_method = canon_method; +b->bodylength = bodylength; +if (!exim_sha_init(&b->body_hash_ctx, /*XXX hash method: extend for sha512 */ + pdkim_hashes[hashtype].exim_hashmethod)) + { + DEBUG(D_acl) + debug_printf("DKIM: hash init error, possibly nonhandled hashtype\n"); + return NULL; + } +b->signed_body_bytes = 0; +b->num_buffered_blanklines = 0; +ctx->bodyhash = b; +return b; +} + + +/* Set up a blob for calculating the bodyhash according to the +needs of this signature. Use an existing one if possible, or +create a new one. + +Return: hashblob pointer, or NULL on error (only used as a boolean). +*/ +pdkim_bodyhash * +pdkim_set_sig_bodyhash(pdkim_ctx * ctx, pdkim_signature * sig) +{ +pdkim_bodyhash * b = pdkim_set_bodyhash(ctx, + sig->hashtype, sig->canon_body, sig->bodylength); +sig->calc_body_hash = b; +return b; +} + + +/* -------------------------------------------------------------------------- */ + + +void +pdkim_init_context(pdkim_ctx * ctx, BOOL dot_stuffed, + uschar * (*dns_txt_callback)(const uschar *)) +{ +memset(ctx, 0, sizeof(pdkim_ctx)); +ctx->flags = dot_stuffed ? PDKIM_MODE_SIGN | PDKIM_DOT_TERM : PDKIM_MODE_SIGN; +/* The line buffer is for message data, hence tainted */ +ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN, TRUE); +DEBUG(D_acl) ctx->dns_txt_callback = dns_txt_callback; } void pdkim_init(void) { -exim_rsa_init(); +exim_dkim_init(); }