-/*
- * PDKIM - a RFC4871 (DKIM) implementation
- *
- * Copyright (C) 2009 - 2016 Tom Kistner <tom@duncanthrax.net>
- * Copyright (C) 2016 - 2018 Jeremy Harris <jgh@exim.org>
- *
- * http://duncanthrax.net/pdkim/
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
-
-#include "../exim.h"
-
-
-#ifndef DISABLE_DKIM /* entire file */
-
-#ifndef SUPPORT_TLS
-# error Need SUPPORT_TLS for DKIM
-#endif
-
-#include "crypt_ver.h"
-
-#ifdef SIGN_OPENSSL
-# include <openssl/rsa.h>
-# include <openssl/ssl.h>
-# include <openssl/err.h>
-#elif defined(SIGN_GNUTLS)
-# include <gnutls/gnutls.h>
-# include <gnutls/x509.h>
-#endif
-
-#include "pdkim.h"
-#include "signing.h"
-
-#define PDKIM_SIGNATURE_VERSION "1"
-#define PDKIM_PUB_RECORD_VERSION US "DKIM1"
-
-#define PDKIM_MAX_HEADER_LEN 65536
-#define PDKIM_MAX_HEADERS 512
-#define PDKIM_MAX_BODY_LINE_LEN 16384
-#define PDKIM_DNS_TXT_MAX_NAMELEN 1024
-
-/* -------------------------------------------------------------------------- */
-struct pdkim_stringlist {
- uschar * value;
- int tag;
- void * next;
-};
-
-/* -------------------------------------------------------------------------- */
-/* A bunch of list constants */
-const uschar * pdkim_querymethods[] = {
- US"dns/txt",
- NULL
-};
-const uschar * pdkim_canons[] = {
- US"simple",
- US"relaxed",
- NULL
-};
-
-const pdkim_hashtype pdkim_hashes[] = {
- { US"sha1", HASH_SHA1 },
- { US"sha256", HASH_SHA2_256 },
- { US"sha512", HASH_SHA2_512 }
-};
-
-const uschar * pdkim_keytypes[] = {
- [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;
-} pdkim_combined_canon_entry;
-
-pdkim_combined_canon_entry pdkim_combined_canons[] = {
- { US"simple/simple", PDKIM_CANON_SIMPLE, PDKIM_CANON_SIMPLE },
- { US"simple/relaxed", PDKIM_CANON_SIMPLE, PDKIM_CANON_RELAXED },
- { US"relaxed/simple", PDKIM_CANON_RELAXED, PDKIM_CANON_SIMPLE },
- { US"relaxed/relaxed", PDKIM_CANON_RELAXED, PDKIM_CANON_RELAXED },
- { US"simple", PDKIM_CANON_SIMPLE, PDKIM_CANON_SIMPLE },
- { US"relaxed", PDKIM_CANON_RELAXED, PDKIM_CANON_SIMPLE },
- { NULL, 0, 0 }
-};
-
-
-static 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);
-}
-
-
-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)
-{
-switch(status)
- {
- case PDKIM_VERIFY_NONE: return "PDKIM_VERIFY_NONE";
- case PDKIM_VERIFY_INVALID: return "PDKIM_VERIFY_INVALID";
- case PDKIM_VERIFY_FAIL: return "PDKIM_VERIFY_FAIL";
- case PDKIM_VERIFY_PASS: return "PDKIM_VERIFY_PASS";
- default: return "PDKIM_VERIFY_UNKNOWN";
- }
-}
-
-const char *
-pdkim_verify_ext_status_str(int ext_status)
-{
-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_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 uschar *
-pdkim_errstr(int status)
-{
-switch(status)
- {
- 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 */
-void
-pdkim_quoteprint(const uschar *data, int len)
-{
-for (int i = 0; i < len; i++)
- {
- const int c = data[i];
- switch (c)
- {
- case ' ' : debug_printf("{SP}"); break;
- case '\t': debug_printf("{TB}"); break;
- case '\r': debug_printf("{CR}"); break;
- case '\n': debug_printf("{LF}"); break;
- case '{' : debug_printf("{BO}"); break;
- case '}' : debug_printf("{BC}"); break;
- default:
- if ( (c < 32) || (c > 127) )
- debug_printf("{%02x}", c);
- else
- debug_printf("%c", c);
- break;
- }
- }
-debug_printf("\n");
-}
-
-void
-pdkim_hexprint(const uschar *data, int len)
-{
-if (data) for (int i = 0 ; i < len; i++) debug_printf("%02x", data[i]);
-else debug_printf("<NULL>");
-debug_printf("\n");
-}
-
-
-
-static pdkim_stringlist *
-pdkim_prepend_stringlist(pdkim_stringlist * base, const uschar * str)
-{
-pdkim_stringlist * new_entry = store_get(sizeof(pdkim_stringlist));
-
-memset(new_entry, 0, sizeof(pdkim_stringlist));
-new_entry->value = string_copy(str);
-if (base) new_entry->next = base;
-return new_entry;
-}
-
-
-
-/* Trim whitespace fore & aft */
-
-static void
-pdkim_strtrim(gstring * str)
-{
-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);
-}
-
-
-
-/* -------------------------------------------------------------------------- */
-
-DLLEXPORT void
-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. 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)
-{
-const uschar * ticklist = tick;
-int sep = ':';
-BOOL multisign;
-uschar * hname, * p, * ele;
-uschar * hcolon = Ustrchr(header, ':'); /* Get header name */
-
-if (!hcolon)
- return PDKIM_FAIL; /* This isn't a header */
-
-/* if we had strncmpic() we wouldn't need this copy */
-hname = string_copyn(header, hcolon-header);
-
-while (p = US ticklist, ele = string_nextinlist(&ticklist, &sep, NULL, 0))
- {
- switch (*ele)
- {
- case '=': case '+': multisign = TRUE; ele++; break;
- default: multisign = FALSE; break;
- }
-
- if (strcmpic(ele, hname) == 0)
- {
- if (!multisign)
- *p = '_'; /* Invalidate this header name instance in tick-off list */
- return PDKIM_OK;
- }
- }
-return PDKIM_FAIL;
-}
-
-
-/* -------------------------------------------------------------------------- */
-/* Performs "relaxed" canonicalization of a header. */
-
-uschar *
-pdkim_relax_header_n(const uschar * header, int len, BOOL append_crlf)
-{
-BOOL past_field_name = FALSE;
-BOOL seen_wsp = FALSE;
-uschar * relaxed = store_get(len+3);
-uschar * q = relaxed;
-
-for (const uschar * p = header; p - header < len; p++)
- {
- uschar c = *p;
-
- if (c == '\r' || c == '\n') /* Ignore CR & LF */
- continue;
- if (c == '\t' || c == ' ')
- {
- if (seen_wsp)
- continue;
- c = ' '; /* Turns WSP into SP */
- seen_wsp = TRUE;
- }
- else
- if (!past_field_name && c == ':')
- {
- 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
- seen_wsp = FALSE;
-
- /* Lowercase header name */
- if (!past_field_name) c = tolower(c);
- *q++ = c;
- }
-
-if (q > relaxed && q[-1] == ' ') q--; /* Squash eventual trailing SP */
-
-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 const uschar *
-pdkim_decode_qp_char(const uschar *qp_p, int *c)
-{
-const uschar *initial_pos = qp_p;
-
-/* Advance one char */
-qp_p++;
-
-/* Check for two hex digits and decode them */
-if (isxdigit(*qp_p) && isxdigit(qp_p[1]))
- {
- /* Do hex conversion */
- *c = (isdigit(*qp_p) ? *qp_p - '0' : toupper(*qp_p) - 'A' + 10) << 4;
- *c |= isdigit(qp_p[1]) ? qp_p[1] - '0' : toupper(qp_p[1]) - 'A' + 10;
- return qp_p + 2;
- }
-
-/* Illegal char here */
-*c = PDKIM_QP_ERROR_DECODE;
-return initial_pos;
-}
-
-
-/* -------------------------------------------------------------------------- */
-
-static uschar *
-pdkim_decode_qp(const uschar * str)
-{
-int nchar = 0;
-uschar * q;
-const uschar * p = str;
-uschar * n = store_get(Ustrlen(str)+1);
-
-*n = '\0';
-q = n;
-while (*p)
- {
- if (*p == '=')
- {
- p = pdkim_decode_qp_char(p, &nchar);
- if (nchar >= 0)
- {
- *q++ = nchar;
- continue;
- }
- }
- else
- *q++ = *p;
- p++;
- }
-*q = '\0';
-return n;
-}
-
-
-/* -------------------------------------------------------------------------- */
-
-void
-pdkim_decode_base64(const uschar * str, blob * b)
-{
-int dlen = b64decode(str, &b->data);
-if (dlen < 0) b->data = NULL;
-b->len = dlen;
-}
-
-uschar *
-pdkim_encode_base64(blob * b)
-{
-return b64encode(b->data, b->len);
-}
-
-
-/* -------------------------------------------------------------------------- */
-#define PDKIM_HDR_LIMBO 0
-#define PDKIM_HDR_TAG 1
-#define PDKIM_HDR_VALUE 2
-
-static pdkim_signature *
-pdkim_parse_sig_header(pdkim_ctx * ctx, uschar * raw_hdr)
-{
-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;
-
-sig = store_get(sizeof(pdkim_signature));
-memset(sig, 0, sizeof(pdkim_signature));
-sig->bodylength = -1;
-
-/* Set so invalid/missing data error display is accurate */
-sig->version = 0;
-sig->keytype = -1;
-sig->hashtype = -1;
-
-q = sig->rawsig_no_b_val = store_get(Ustrlen(raw_hdr)+1);
-
-for (uschar * p = raw_hdr; ; p++)
- {
- char c = *p;
-
- /* Ignore FWS */
- if (c == '\r' || c == '\n')
- goto NEXT_CHAR;
-
- /* Fast-forward through header name */
- if (!past_hname)
- {
- if (c == ':') past_hname = TRUE;
- goto NEXT_CHAR;
- }
-
- if (where == PDKIM_HDR_LIMBO)
- {
- /* In limbo, just wait for a tag-char to appear */
- if (!(c >= 'a' && c <= 'z'))
- goto NEXT_CHAR;
-
- where = PDKIM_HDR_TAG;
- }
-
- if (where == PDKIM_HDR_TAG)
- {
- if (c >= 'a' && c <= 'z')
- cur_tag = string_catn(cur_tag, p, 1);
-
- if (c == '=')
- {
- if (Ustrcmp(string_from_gstring(cur_tag), "b") == 0)
- {
- *q++ = '=';
- in_b_val = TRUE;
- }
- where = PDKIM_HDR_VALUE;
- goto NEXT_CHAR;
- }
- }
-
- if (where == PDKIM_HDR_VALUE)
- {
- if (c == '\r' || c == '\n' || c == ' ' || c == '\t')
- goto NEXT_CHAR;
-
- if (c == ';' || c == '\0')
- {
- /* 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')
- )
- {
- (void) string_from_gstring(cur_val);
- pdkim_strtrim(cur_val);
-
- DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag->s, cur_val->s);
-
- switch (*cur_tag->s)
- {
- 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': /* version */
- /* We only support version 1, and that is currently the
- only version there is. */
- sig->version =
- Ustrcmp(cur_val->s, PDKIM_SIGNATURE_VERSION) == 0 ? 1 : -1;
- break;
- case 'a': /* algorithm */
- {
- const uschar * list = cur_val->s;
- int sep = '-';
- uschar * elem;
-
- if ((elem = string_nextinlist(&list, &sep, NULL, 0)))
- for (int i = 0; i < nelem(pdkim_keytypes); i++)
- if (Ustrcmp(elem, pdkim_keytypes[i]) == 0)
- { sig->keytype = i; break; }
- 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': /* Query method (for pubkey)*/
- for (int i = 0; pdkim_querymethods[i]; i++)
- if (Ustrcmp(cur_val->s, pdkim_querymethods[i]) == 0)
- {
- sig->querymethod = i; /* we never actually use this */
- break;
- }
- 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;
- }
- }
- cur_tag = cur_val = NULL;
- in_b_val = FALSE;
- where = PDKIM_HDR_LIMBO;
- }
- else
- cur_val = string_catn(cur_val, p, 1);
- }
-
-NEXT_CHAR:
- if (c == '\0')
- break;
-
- if (!in_b_val)
- *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'))
- *q = '\0';
-
-DEBUG(D_acl)
- {
- debug_printf(
- "PDKIM >> 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->sighash.len*8);
- debug_printf(
- "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
- }
-
-if (!pdkim_set_sig_bodyhash(ctx, sig))
- return NULL;
-
-return sig;
-}
-
-
-/* -------------------------------------------------------------------------- */
-
-pdkim_pubkey *
-pdkim_parse_pubkey_record(const uschar *raw_record)
-{
-const uschar * ele;
-int sep = ';';
-pdkim_pubkey * pub;
-
-pub = store_get(sizeof(pdkim_pubkey));
-memset(pub, 0, sizeof(pdkim_pubkey));
-
-while ((ele = string_nextinlist(&raw_record, &sep, NULL, 0)))
- {
- const uschar * val;
-
- if ((val = Ustrchr(ele, '=')))
- {
- int taglen = val++ - ele;
-
- DEBUG(D_acl) debug_printf(" %.*s=%s\n", taglen, ele, val);
- switch (ele[0])
- {
- 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;
- }
- }
- }
-
-/* Set fallback defaults */
-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 = 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;
-}
-
-
-/* -------------------------------------------------------------------------- */
-
-/* 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, blob * orig_data, blob * relaxed_data)
-{
-blob * canon_data = orig_data;
-/* Defaults to simple canon (no further treatment necessary) */
-
-if (b->canon_method == PDKIM_CANON_RELAXED)
- {
- /* Relax the line if not done already */
- if (!relaxed_data)
- {
- 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(). */
-
- relaxed_data = store_malloc(sizeof(blob) + orig_data->len+1);
- relaxed_data->data = US (relaxed_data+1);
-
- 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--;
- }
- 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;
- }
- 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 ( b->bodylength >= 0
- && b->signed_body_bytes + (unsigned long)canon_data->len > b->bodylength
- )
- canon_data->len = b->bodylength - b->signed_body_bytes;
-
-if (canon_data->len > 0)
- {
- exim_sha_update(&b->body_hash_ctx, CUS canon_data->data, canon_data->len);
- b->signed_body_bytes += canon_data->len;
- DEBUG(D_acl) pdkim_quoteprint(canon_data->data, canon_data->len);
- }
-
-return relaxed_data;
-}
-
-
-/* -------------------------------------------------------------------------- */
-
-static void
-pdkim_finish_bodyhash(pdkim_ctx * ctx)
-{
-for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next) /* Finish hashes */
- {
- DEBUG(D_acl) debug_printf("PDKIM: 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 (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 (%s) hashed: %lu\n"
- "PDKIM [%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)
- {
- /* If bodylength limit is set, and we have received less bytes
- than the requested amount, effectively remove the limit tag. */
- if (b->signed_body_bytes < sig->bodylength)
- sig->bodylength = -1;
- }
-
- else
- /* VERIFICATION --------------------------------------------------------- */
- /* Be careful that the header sig included a bodyash */
-
- if ( sig->bodyhash.data
- && memcmp(b->bh.data, sig->bodyhash.data, b->bh.len) == 0)
- {
- DEBUG(D_acl) debug_printf("PDKIM [%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, sig->bodyhash.len);
- debug_printf("PDKIM [%s] Body hash did NOT verify\n", sig->domain);
- }
- sig->verify_status = PDKIM_VERIFY_FAIL;
- sig->verify_ext_status = PDKIM_VERIFY_FAIL_BODY;
- }
- }
-}
-
-
-
-static void
-pdkim_body_complete(pdkim_ctx * ctx)
-{
-/* 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 */
-
-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;
-}
-
-
-
-/* -------------------------------------------------------------------------- */
-/* Call from pdkim_feed below for processing complete body lines */
-/* NOTE: the line is not NUL-terminated; but we have a count */
-
-static void
-pdkim_bodyline_complete(pdkim_ctx * ctx)
-{
-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 all_skip;
-
-/* We've always got one extra byte to stuff a zero ... */
-ctx->linebuf[line.len] = '\0';
-
-/* Terminate on EOD marker */
-if (ctx->flags & PDKIM_DOT_TERM)
- {
- if (memcmp(line.data, ".\r\n", 3) == 0)
- { pdkim_body_complete(ctx); return; }
-
- /* Unstuff dots */
- 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(line.data, "\r\n", 2) == 0)
- {
- for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next)
- b->num_buffered_blanklines++;
- goto all_skip;
- }
-
-/* Process line for each bodyhash separately */
-for (pdkim_bodyhash * b = ctx->bodyhash; b; b = b->next)
- {
- if (b->canon_method == PDKIM_CANON_RELAXED)
- {
- /* 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++;
- }
-
- b->num_buffered_blanklines++;
- goto hash_skip;
- }
-
-hash_process:
- /* At this point, we have a non-empty line, so release the buffered ones. */
-
- 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: ;
- }
-
-if (rnl) store_free(rnl);
-if (rline) store_free(rline);
-
-all_skip:
-
-ctx->linebuf_offset = 0;
-return;
-}
-
-
-/* -------------------------------------------------------------------------- */
-/* Callback from pdkim_feed below for processing complete headers */
-#define DKIM_SIGNATURE_HEADERNAME "DKIM-Signature:"
-
-static int
-pdkim_header_complete(pdkim_ctx * ctx)
-{
-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
-
-if (++ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL;
-
-/* SIGNING -------------------------------------------------------------- */
-if (ctx->flags & PDKIM_MODE_SIGN)
- 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->s);
-
-/* VERIFICATION ----------------------------------------------------------- */
-/* DKIM-Signature: headers are added to the verification list */
-else
- {
-#ifdef notdef
- DEBUG(D_acl)
- {
- debug_printf("PDKIM >> 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 * 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. */
-
- DEBUG(D_acl) debug_printf(
- "PDKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
-
- sig = pdkim_parse_sig_header(ctx, ctx->cur_header->s);
-
- if (!(last_sig = ctx->sig))
- ctx->sig = sig;
- else
- {
- while (last_sig->next) last_sig = last_sig->next;
- last_sig->next = sig;
- }
-
- if (--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;
- }
- }
-
- /* all headers are stored for signature verification */
- ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header->s);
- }
-
-BAIL:
-ctx->cur_header->s[ctx->cur_header->ptr = 0] = '\0'; /* leave buffer for reuse */
-return PDKIM_OK;
-}
-
-
-
-/* -------------------------------------------------------------------------- */
-#define HEADER_BUFFER_FRAG_SIZE 256
-
-DLLEXPORT int
-pdkim_feed(pdkim_ctx * ctx, uschar * data, int len)
-{
-/* Alternate EOD signal, used in non-dotstuffing mode */
-if (!data)
- pdkim_body_complete(ctx);
-
-else for (int p = 0; p < len; p++)
- {
- uschar c = data[p];
- int rc;
-
- if (ctx->flags & 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 == '\r')
- ctx->flags |= PDKIM_SEEN_CR;
- else if (c == '\n')
- {
- ctx->flags &= ~PDKIM_SEEN_CR;
- pdkim_bodyline_complete(ctx);
- }
-
- if (ctx->linebuf_offset == PDKIM_MAX_BODY_LINE_LEN-1)
- return PDKIM_ERR_LONG_LINE;
- }
- else
- {
- /* Processing header byte */
- if (c == '\r')
- ctx->flags |= PDKIM_SEEN_CR;
- else if (c == '\n')
- {
- if (!(ctx->flags & PDKIM_SEEN_CR)) /* emulate the CR */
- ctx->cur_header = string_catn(ctx->cur_header, CUS "\r", 1);
-
- 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(
- "PDKIM >> 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 || ctx->cur_header->ptr < PDKIM_MAX_HEADER_LEN)
- ctx->cur_header = string_catn(ctx->cur_header, CUS &data[p], 1);
- }
- }
-return PDKIM_OK;
-}
-
-
-
-/* Extend a growing header with a continuation-linebreak */
-static gstring *
-pdkim_hdr_cont(gstring * str, int * col)
-{
-*col = 1;
-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)
- *
- * col: this int holds and receives column number (octets since last '\n')
- * str: partial string to append to
- * pad: padding, split line or space after before or after eg: ";"
- * intro: - must join to payload eg "h=", usually the tag name
- * payload: eg base64 data - long data can be split arbitrarily.
- *
- * this code doesn't fold the header in some of the places that RFC4871
- * allows: As per RFC5322(2.2.3) it only folds before or after tag-value
- * 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
- * names longer than 78, or bogus col. Input is assumed to be free of line breaks.
- */
-
-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, col);
- str = string_catn(str, 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, 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, US" ", 1);
- *col += 1;
- pad = NULL; /* only want this once */
- l--;
- }
-
- if (intro)
- {
- size_t sl = Ustrlen(intro);
-
- str = string_catn(str, intro, sl);
- *col += sl;
- l -= sl;
- intro = NULL; /* only want this once */
- }
-
- if (payload)
- {
- size_t sl = Ustrlen(payload);
- size_t chomp = *col+sl < 77 ? sl : 78-*col;
-
- str = string_catn(str, payload, chomp);
- *col += chomp;
- payload += chomp;
- l -= chomp-1;
- }
-
- /* the while precondition tells us it didn't fit. */
- str = pdkim_hdr_cont(str, col);
- }
-
-if (*col + l > 78)
- {
- str = pdkim_hdr_cont(str, col);
- pad = NULL;
- }
-
-if (pad)
- {
- str = string_catn(str, US" ", 1);
- *col += 1;
- pad = NULL;
- }
-
-if (intro)
- {
- size_t sl = Ustrlen(intro);
-
- str = string_catn(str, intro, sl);
- *col += sl;
- l -= sl;
- intro = NULL;
- }
-
-if (payload)
- {
- size_t sl = Ustrlen(payload);
-
- str = string_catn(str, payload, sl);
- *col += sl;
- }
-
-return str;
-}
-
-
-/* -------------------------------------------------------------------------- */
-
-/* Signing: create signature header
-*/
-static uschar *
-pdkim_create_header(pdkim_signature * sig, BOOL final)
-{
-uschar * base64_bh;
-uschar * base64_b;
-int col = 0;
-gstring * hdr;
-gstring * canon_all;
-
-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, US"DKIM-Signature: v="PDKIM_SIGNATURE_VERSION);
-col = hdr->ptr;
-
-/* Required and static bits */
-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. */
- {
- uschar * n = string_copy(sig->headernames);
- uschar * i = US"h=";
- uschar * s = US";";
-
- while (*n)
- {
- uschar * c = Ustrchr(n, ':');
-
- if (c) *c ='\0';
-
- if (!i)
- hdr = pdkim_headcat(&col, hdr, NULL, NULL, US":");
-
- hdr = pdkim_headcat(&col, hdr, s, i, n);
-
- if (!c)
- break;
-
- n = c+1;
- s = NULL;
- i = NULL;
- }
- }
-
-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, 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, US";", US"t=", minibuf);
-}
-
-if (sig->expires > 0)
- {
- uschar minibuf[20];
-
- snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->expires);
- hdr = pdkim_headcat(&col, hdr, US";", US"x=", minibuf);
- }
-
-if (sig->bodylength >= 0)
- {
- uschar minibuf[20];
-
- snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->bodylength);
- hdr = pdkim_headcat(&col, hdr, US";", US"l=", minibuf);
- }
-
-/* Preliminary or final version? */
-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, 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"");
- }
-
-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("PDKIM: unexpected pubkey len %lu\n", 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,
- const uschar ** errstr)
-{
-uschar * dns_txt_name, * dns_txt_reply;
-pdkim_pubkey * p;
-
-/* Fetch public key for signing domain, from DNS */
-
-dns_txt_name = string_sprintf("%s._domainkey.%s.", sig->selector, sig->domain);
-
-if ( !(dns_txt_reply = ctx->dns_txt_callback(dns_txt_name))
- || dns_txt_reply[0] == '\0'
- )
- {
- sig->verify_status = PDKIM_VERIFY_INVALID;
- sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE;
- return NULL;
- }
-
-DEBUG(D_acl)
- {
- debug_printf(
- "PDKIM >> 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(CUS dns_txt_reply))
- || (Ustrcmp(p->srvtype, "*") != 0 && Ustrcmp(p->srvtype, "email") != 0)
- )
- {
- sig->verify_status = PDKIM_VERIFY_INVALID;
- sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD;
-
- DEBUG(D_acl)
- {
- if (p)
- debug_printf(" Invalid public key service type '%s'\n", p->srvtype);
- else
- debug_printf(" Error while parsing public key record\n");
- debug_printf(
- "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
- }
- return NULL;
- }
-
-DEBUG(D_acl) debug_printf(
- "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
-
-/* Import public key */
-
-/* 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)
- {
- for(int i = 0; i < nelem(pdkim_keytypes); i++)
- if (Ustrcmp(p->keytype, pdkim_keytypes[i]) == 0)
- { sig->keytype = i; goto k_ok; }
- 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;
- }
-k_ok:
-
-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)))
- {
- 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;
-}
-
-
-/* -------------------------------------------------------------------------- */
-
-DLLEXPORT int
-pdkim_feed_finish(pdkim_ctx * ctx, pdkim_signature ** return_signatures,
- const uschar ** err)
-{
-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 '<CR><LF>' */
-if (ctx->cur_header && ctx->cur_header->ptr > 0)
- {
- 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");
-
-/* Build (and/or evaluate) body hash. Do this even if no DKIM sigs, in case we
-have a hash to do for ARC. */
-
-pdkim_finish_bodyhash(ctx);
-
-if (!ctx->sig)
- {
- DEBUG(D_acl) debug_printf("PDKIM: no signatures\n");
- *return_signatures = NULL;
- return PDKIM_OK;
- }
-
-for (pdkim_signature * sig = ctx->sig; sig; sig = sig->next)
- {
- hctx hhash_ctx;
- uschar * sig_hdr = US"";
- blob hhash;
- gstring * hdata = NULL;
- es_ctx sctx;
-
- if ( !(ctx->flags & PDKIM_MODE_SIGN)
- && sig->verify_status == PDKIM_VERIFY_FAIL)
- {
- DEBUG(D_acl)
- debug_printf("PDKIM: [%s] abandoning this signature\n", sig->domain);
- continue;
- }
-
- /*XXX The hash of the headers is needed for GCrypt (for which we can do RSA
- suging 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,
- "PDKIM: hash setup error, possibly nonhandled hashtype");
- break;
- }
-
- if (ctx->flags & PDKIM_MODE_SIGN)
- DEBUG(D_acl) debug_printf(
- "PDKIM >> Headers to be signed: >>>>>>>>>>>>\n"
- " %s\n",
- sig->sign_headers);
-
- DEBUG(D_acl) debug_printf(
- "PDKIM >> 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
- go, construct a list of the header's names to use for the h= parameter.
- Then append to that list any remaining header names for which there was no
- header to sign. */
-
- if (ctx->flags & PDKIM_MODE_SIGN)
- {
- gstring * g = NULL;
- const uschar * l;
- uschar * s;
- int sep = 0;
-
- /* Import private key, including the keytype which we need for building
- the signature header */
-
-/*XXX extend for non-RSA algos */
- 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)
- {
- /* Collect header names (Note: colon presence is guaranteed here) */
- g = string_append_listele_n(g, ':', rh, Ustrchr(rh, ':') - rh);
-
- 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) */
- /*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 == '+') /* 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);
- }
-
- /* VERIFICATION ----------------------------------------------------------- */
- /* When verifying, walk through the header name list in the h= parameter and
- add the headers to the hash in that order. */
- else
- {
- uschar * p = sig->headernames;
- uschar * q;
-
- if (p)
- {
- /* clear tags */
- for (pdkim_stringlist * hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
- hdrs->tag = 0;
-
- p = string_copy(p);
- while(1)
- {
- if ((q = Ustrchr(p, ':')))
- *q = '\0';
-
- /*XXX walk the list of headers in same order as received. */
- 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)] == ':'
- )
- {
- /* cook header for relaxed canon, or just copy it for simple */
-
- uschar * rh = sig->canon_headers == PDKIM_CANON_RELAXED
- ? pdkim_relax_header(hdrs->value, TRUE)
- : string_copy(CUS hdrs->value);
-
- /* Feed header to the hash algorithm */
- exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
-
- DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh));
- hdrs->tag = 1;
- break;
- }
-
- if (!q) break;
- p = q+1;
- }
-
- sig_hdr = string_copy(sig->rawsig_no_b_val);
- }
- }
-
- DEBUG(D_acl) debug_printf(
- "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
-
- DEBUG(D_acl)
- {
- debug_printf(
- "PDKIM >> Signed DKIM-Signature header, pre-canonicalized >>>>>>>>>>>>>\n");
- pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr));
- debug_printf(
- "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
- }
-
- /* Relax header if necessary */
- if (sig->canon_headers == PDKIM_CANON_RELAXED)
- sig_hdr = pdkim_relax_header(sig_hdr, FALSE);
-
- DEBUG(D_acl)
- {
- debug_printf("PDKIM >> Signed DKIM-Signature header, canonicalized (%-7s) >>>>>>>\n",
- pdkim_canons[sig->canon_headers]);
- pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr));
- debug_printf(
- "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
- }
-
- /* Finalize header hash */
- exim_sha_update(&hhash_ctx, CUS sig_hdr, Ustrlen(sig_hdr));
- exim_sha_finish(&hhash_ctx, &hhash);
-
- DEBUG(D_acl)
- {
- debug_printf("PDKIM [%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 signing library cannot do
- incremental) */
- if (ctx->flags & PDKIM_MODE_SIGN)
- hdata = exim_dkim_data_append(hdata, US sig_hdr);
-
- /* SIGNING ---------------------------------------------------------------- */
- if (ctx->flags & PDKIM_MODE_SIGN)
- {
- hashmethod hm = sig->keytype == KEYTYPE_ED25519
-#if defined(SIGN_OPENSSL)
- ? HASH_NULL
-#else
- ? HASH_SHA2_512
-#endif
- : pdkim_hashes[sig->hashtype].exim_hashmethod;
-
-#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 (sig->keytype != KEYTYPE_ED25519)
-#endif
- {
- hhash.data = hdata->s;
- hhash.len = hdata->ptr;
- }
-
- if ((*err = exim_dkim_sign(&sctx, hm, &hhash, &sig->sighash)))
- {
- 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->sighash.data, sig->sighash.len);
- }
-
- sig->signature_header = pdkim_create_header(sig, TRUE);
- }
-
- /* VERIFICATION ----------------------------------------------------------- */
- else
- {
- ev_ctx vctx;
- 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->sighash.data
- && sig->keytype >= 0
- && sig->hashtype >= 0
- && sig->version
- ) )
- {
- sig->verify_status = PDKIM_VERIFY_INVALID;
- sig->verify_ext_status = PDKIM_VERIFY_INVALID_SIGNATURE_ERROR;
-
- DEBUG(D_acl) debug_printf(
- " Error in DKIM-Signature header: tags missing or invalid (%s)\n"
- "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\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;
- }
-
- /* Make sure sig uses supported DKIM version (only v1) */
- if (sig->version != 1)
- {
- sig->verify_status = PDKIM_VERIFY_INVALID;
- sig->verify_ext_status = PDKIM_VERIFY_INVALID_DKIM_VERSION;
-
- DEBUG(D_acl) debug_printf(
- " Error in DKIM-Signature header: unsupported DKIM version\n"
- "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
- goto NEXT_VERIFY;
- }
-
- DEBUG(D_acl)
- {
- debug_printf( "PDKIM [%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, "PDKIM: %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 ((*err = exim_dkim_verify(&vctx, hm, &hhash, &sig->sighash)))
- {
- 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;
- }
-
-
- /* 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;
- }
-
-NEXT_VERIFY:
-
- DEBUG(D_acl)
- {
- debug_printf("PDKIM [%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));
- else
- debug_printf("\n");
- }
- }
- }
-
-/* If requested, set return pointer to signature(s) */
-if (return_signatures)
- *return_signatures = ctx->sig;
-
-return ctx->flags & PDKIM_MODE_SIGN || verify_pass
- ? PDKIM_OK : PDKIM_FAIL;
-}
-
-
-/* -------------------------------------------------------------------------- */
-
-DLLEXPORT pdkim_ctx *
-pdkim_init_verify(uschar * (*dns_txt_callback)(uschar *), BOOL dot_stuffing)
-{
-pdkim_ctx * ctx;
-
-ctx = store_get(sizeof(pdkim_ctx));
-memset(ctx, 0, sizeof(pdkim_ctx));
-
-if (dot_stuffing) ctx->flags = PDKIM_DOT_TERM;
-ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN);
-ctx->dns_txt_callback = dns_txt_callback;
-
-return ctx;
-}
-
-
-/* -------------------------------------------------------------------------- */
-
-DLLEXPORT pdkim_signature *
-pdkim_init_sign(pdkim_ctx * ctx,
- uschar * domain, uschar * selector, uschar * privkey,
- uschar * hashname, const uschar ** errstr)
-{
-int hashtype;
-pdkim_signature * sig;
-
-if (!domain || !selector || !privkey)
- return NULL;
-
-/* Allocate & init one signature struct */
-
-sig = store_get(sizeof(pdkim_signature));
-memset(sig, 0, sizeof(pdkim_signature));
-
-sig->bodylength = -1;
-
-sig->domain = string_copy(US domain);
-sig->selector = string_copy(US selector);
-sig->privkey = string_copy(US privkey);
-sig->keytype = -1;
-
-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,
- "PDKIM: 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, errstr))
- debug_printf("WARNING: bad dkim key in dns\n");
- debug_printf("PDKIM (finished checking verify key)<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
- }
-return sig;
-}
-
-
-/* -------------------------------------------------------------------------- */
-
-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)
-{
-if (identity)
- sig->identity = string_copy(US identity);
-
-sig->sign_headers = string_copy(sign_headers
- ? US sign_headers : US PDKIM_DEFAULT_SIGN_HEADERS);
-
-sig->canon_headers = canon_headers;
-sig->canon_body = canon_body;
-sig->bodylength = bodylength;
-sig->created = created;
-sig->expires = expires;
-
-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;
-
-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("PDKIM: using existing bodyhash %d/%d/%ld\n",
- hashtype, canon_method, bodylength);
- return b;
- }
-
-DEBUG(D_receive) debug_printf("PDKIM: new bodyhash %d/%d/%ld\n",
- hashtype, canon_method, bodylength);
-b = store_get(sizeof(pdkim_bodyhash));
-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("PDKIM: 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)(uschar *))
-{
-memset(ctx, 0, sizeof(pdkim_ctx));
-ctx->flags = dot_stuffed ? PDKIM_MODE_SIGN | PDKIM_DOT_TERM : PDKIM_MODE_SIGN;
-ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN);
-DEBUG(D_acl) ctx->dns_txt_callback = dns_txt_callback;
-}
-
-
-void
-pdkim_init(void)
-{
-exim_dkim_init();
-}
-
-
-
-#endif /*DISABLE_DKIM*/
git://git.exim.org / exim.git / blobdiff