diff options
Diffstat (limited to 'tools/wks-receive.c')
| -rw-r--r-- | tools/wks-receive.c | 534 |
1 files changed, 534 insertions, 0 deletions
diff --git a/tools/wks-receive.c b/tools/wks-receive.c new file mode 100644 index 0000000..e5d2ed4 --- /dev/null +++ b/tools/wks-receive.c @@ -0,0 +1,534 @@ +/* wks-receive.c - Receive a WKS mail + * Copyright (C) 2016 g10 Code GmbH + * Copyright (C) 2016 Bundesamt für Sicherheit in der Informationstechnik + * + * This file is part of GnuPG. + * + * This file is free software; you can redistribute it and/or modify + * it under the terms of the GNU Lesser General Public License as + * published by the Free Software Foundation; either version 2.1 of + * the License, or (at your option) any later version. + * + * This file 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 Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public License + * along with this program; if not, see <https://www.gnu.org/licenses/>. + */ + +#include <config.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "../common/util.h" +#include "../common/ccparray.h" +#include "../common/exectool.h" +#include "gpg-wks.h" +#include "rfc822parse.h" +#include "mime-parser.h" + + +/* Limit of acceptable signed data. */ +#define MAX_SIGNEDDATA 10000 + +/* Limit of acceptable signature. */ +#define MAX_SIGNATURE 10000 + +/* Limit of acceptable encrypted data. */ +#define MAX_ENCRYPTED 100000 + +/* Data for a received object. */ +struct receive_ctx_s +{ + mime_parser_t parser; + estream_t encrypted; + estream_t plaintext; + estream_t signeddata; + estream_t signature; + estream_t key_data; + estream_t wkd_data; + unsigned int collect_key_data:1; + unsigned int collect_wkd_data:1; + unsigned int draft_version_2:1; /* This is a draft version 2 request. */ + unsigned int multipart_mixed_seen:1; +}; +typedef struct receive_ctx_s *receive_ctx_t; + + + +static void +decrypt_data_status_cb (void *opaque, const char *keyword, char *args) +{ + receive_ctx_t ctx = opaque; + (void)ctx; + if (DBG_CRYPTO) + log_debug ("gpg status: %s %s\n", keyword, args); +} + + +/* Decrypt the collected data. */ +static void +decrypt_data (receive_ctx_t ctx) +{ + gpg_error_t err; + ccparray_t ccp; + const char **argv; + int c; + + es_rewind (ctx->encrypted); + + if (!ctx->plaintext) + ctx->plaintext = es_fopenmem (0, "w+b"); + if (!ctx->plaintext) + { + err = gpg_error_from_syserror (); + log_error ("error allocating space for plaintext: %s\n", + gpg_strerror (err)); + return; + } + + ccparray_init (&ccp, 0); + + ccparray_put (&ccp, "--no-options"); + /* We limit the output to 64 KiB to avoid DoS using compression + * tricks. A regular client will anyway only send a minimal key; + * that is one w/o key signatures and attribute packets. */ + ccparray_put (&ccp, "--max-output=0x10000"); + ccparray_put (&ccp, "--batch"); + if (opt.verbose) + ccparray_put (&ccp, "--verbose"); + ccparray_put (&ccp, "--always-trust"); + ccparray_put (&ccp, "--decrypt"); + ccparray_put (&ccp, "--"); + + ccparray_put (&ccp, NULL); + argv = ccparray_get (&ccp, NULL); + if (!argv) + { + err = gpg_error_from_syserror (); + goto leave; + } + err = gnupg_exec_tool_stream (opt.gpg_program, argv, ctx->encrypted, + NULL, ctx->plaintext, + decrypt_data_status_cb, ctx); + if (err) + { + log_error ("decryption failed: %s\n", gpg_strerror (err)); + goto leave; + } + + if (DBG_CRYPTO) + { + es_rewind (ctx->plaintext); + log_debug ("plaintext: '"); + while ((c = es_getc (ctx->plaintext)) != EOF) + log_printf ("%c", c); + log_printf ("'\n"); + } + es_rewind (ctx->plaintext); + + leave: + xfree (argv); +} + + +static void +verify_signature_status_cb (void *opaque, const char *keyword, char *args) +{ + receive_ctx_t ctx = opaque; + (void)ctx; + if (DBG_CRYPTO) + log_debug ("gpg status: %s %s\n", keyword, args); +} + +/* Verify the signed data. */ +static void +verify_signature (receive_ctx_t ctx) +{ + gpg_error_t err; + ccparray_t ccp; + const char **argv; + + log_assert (ctx->signeddata); + log_assert (ctx->signature); + es_rewind (ctx->signeddata); + es_rewind (ctx->signature); + + ccparray_init (&ccp, 0); + + ccparray_put (&ccp, "--no-options"); + ccparray_put (&ccp, "--batch"); + if (opt.verbose) + ccparray_put (&ccp, "--verbose"); + ccparray_put (&ccp, "--enable-special-filenames"); + ccparray_put (&ccp, "--status-fd=2"); + ccparray_put (&ccp, "--always-trust"); /* To avoid trustdb checks. */ + ccparray_put (&ccp, "--verify"); + ccparray_put (&ccp, "--"); + ccparray_put (&ccp, "-&@INEXTRA@"); + ccparray_put (&ccp, "-"); + + ccparray_put (&ccp, NULL); + argv = ccparray_get (&ccp, NULL); + if (!argv) + { + err = gpg_error_from_syserror (); + goto leave; + } + err = gnupg_exec_tool_stream (opt.gpg_program, argv, ctx->signeddata, + ctx->signature, NULL, + verify_signature_status_cb, ctx); + if (err) + { + log_error ("verification failed: %s\n", gpg_strerror (err)); + goto leave; + } + + log_debug ("Fixme: Verification result is not used\n"); + + leave: + xfree (argv); +} + + +static gpg_error_t +collect_encrypted (void *cookie, const char *data) +{ + receive_ctx_t ctx = cookie; + + if (!ctx->encrypted) + if (!(ctx->encrypted = es_fopenmem (MAX_ENCRYPTED, "w+b,samethread"))) + return gpg_error_from_syserror (); + if (data) + es_fputs (data, ctx->encrypted); + + if (es_ferror (ctx->encrypted)) + return gpg_error_from_syserror (); + + if (!data) + { + decrypt_data (ctx); + } + + return 0; +} + + +static gpg_error_t +collect_signeddata (void *cookie, const char *data) +{ + receive_ctx_t ctx = cookie; + + if (!ctx->signeddata) + if (!(ctx->signeddata = es_fopenmem (MAX_SIGNEDDATA, "w+b,samethread"))) + return gpg_error_from_syserror (); + if (data) + es_fputs (data, ctx->signeddata); + + if (es_ferror (ctx->signeddata)) + return gpg_error_from_syserror (); + return 0; +} + +static gpg_error_t +collect_signature (void *cookie, const char *data) +{ + receive_ctx_t ctx = cookie; + + if (!ctx->signature) + if (!(ctx->signature = es_fopenmem (MAX_SIGNATURE, "w+b,samethread"))) + return gpg_error_from_syserror (); + if (data) + es_fputs (data, ctx->signature); + + if (es_ferror (ctx->signature)) + return gpg_error_from_syserror (); + + if (!data) + { + verify_signature (ctx); + } + + return 0; +} + + +/* The callback for the transition from header to body. We use it to + * look at some header values. */ +static gpg_error_t +t2body (void *cookie, int level) +{ + receive_ctx_t ctx = cookie; + rfc822parse_t msg; + char *value; + size_t valueoff; + + log_info ("t2body for level %d\n", level); + if (!level) + { + /* This is the outermost header. */ + msg = mime_parser_rfc822parser (ctx->parser); + if (msg) + { + value = rfc822parse_get_field (msg, "Wks-Draft-Version", + -1, &valueoff); + if (value) + { + if (atoi(value+valueoff) >= 2 ) + ctx->draft_version_2 = 1; + free (value); + } + } + } + + return 0; +} + + +static gpg_error_t +new_part (void *cookie, const char *mediatype, const char *mediasubtype) +{ + receive_ctx_t ctx = cookie; + gpg_error_t err = 0; + + ctx->collect_key_data = 0; + ctx->collect_wkd_data = 0; + + if (!strcmp (mediatype, "application") + && !strcmp (mediasubtype, "pgp-keys")) + { + log_info ("new '%s/%s' message part\n", mediatype, mediasubtype); + if (ctx->key_data) + { + log_error ("we already got a key - ignoring this part\n"); + err = gpg_error (GPG_ERR_FALSE); + } + else + { + ctx->key_data = es_fopenmem (0, "w+b"); + if (!ctx->key_data) + { + err = gpg_error_from_syserror (); + log_error ("error allocating space for key: %s\n", + gpg_strerror (err)); + } + else + { + ctx->collect_key_data = 1; + err = gpg_error (GPG_ERR_TRUE); /* We want the part decoded. */ + } + } + } + else if (!strcmp (mediatype, "application") + && !strcmp (mediasubtype, "vnd.gnupg.wks")) + { + log_info ("new '%s/%s' message part\n", mediatype, mediasubtype); + if (ctx->wkd_data) + { + log_error ("we already got a wkd part - ignoring this part\n"); + err = gpg_error (GPG_ERR_FALSE); + } + else + { + ctx->wkd_data = es_fopenmem (0, "w+b"); + if (!ctx->wkd_data) + { + err = gpg_error_from_syserror (); + log_error ("error allocating space for key: %s\n", + gpg_strerror (err)); + } + else + { + ctx->collect_wkd_data = 1; + err = gpg_error (GPG_ERR_TRUE); /* We want the part decoded. */ + } + } + } + else if (!strcmp (mediatype, "multipart") + && !strcmp (mediasubtype, "mixed")) + { + ctx->multipart_mixed_seen = 1; + } + else if (!strcmp (mediatype, "text")) + { + /* Check that we receive a text part only after a + * application/mixed. This is actually a too simple test and we + * should eventually employ a strict MIME structure check. */ + if (!ctx->multipart_mixed_seen) + err = gpg_error (GPG_ERR_UNEXPECTED_MSG); + } + else + { + log_error ("unexpected '%s/%s' message part\n", mediatype, mediasubtype); + err = gpg_error (GPG_ERR_FALSE); /* We do not want the part. */ + } + + return err; +} + + +static gpg_error_t +part_data (void *cookie, const void *data, size_t datalen) +{ + receive_ctx_t ctx = cookie; + + if (data) + { + if (DBG_MIME) + log_debug ("part_data: '%.*s'\n", (int)datalen, (const char*)data); + if (ctx->collect_key_data) + { + if (es_write (ctx->key_data, data, datalen, NULL) + || es_fputs ("\n", ctx->key_data)) + return gpg_error_from_syserror (); + } + if (ctx->collect_wkd_data) + { + if (es_write (ctx->wkd_data, data, datalen, NULL) + || es_fputs ("\n", ctx->wkd_data)) + return gpg_error_from_syserror (); + } + } + else + { + if (DBG_MIME) + log_debug ("part_data: finished\n"); + ctx->collect_key_data = 0; + ctx->collect_wkd_data = 0; + } + return 0; +} + + +/* Receive a WKS mail from FP and process it accordingly. On success + * the RESULT_CB is called with the mediatype and a stream with the + * decrypted data. */ +gpg_error_t +wks_receive (estream_t fp, + gpg_error_t (*result_cb)(void *opaque, + const char *mediatype, + estream_t data, + unsigned int flags), + void *cb_data) +{ + gpg_error_t err; + receive_ctx_t ctx; + mime_parser_t parser; + estream_t plaintext = NULL; + int c; + unsigned int flags = 0; + + ctx = xtrycalloc (1, sizeof *ctx); + if (!ctx) + return gpg_error_from_syserror (); + + err = mime_parser_new (&parser, ctx); + if (err) + goto leave; + if (DBG_PARSER) + mime_parser_set_verbose (parser, 1); + mime_parser_set_t2body (parser, t2body); + mime_parser_set_new_part (parser, new_part); + mime_parser_set_part_data (parser, part_data); + mime_parser_set_collect_encrypted (parser, collect_encrypted); + mime_parser_set_collect_signeddata (parser, collect_signeddata); + mime_parser_set_collect_signature (parser, collect_signature); + + ctx->parser = parser; + + err = mime_parser_parse (parser, fp); + if (err) + goto leave; + + if (ctx->key_data) + log_info ("key data found\n"); + if (ctx->wkd_data) + log_info ("wkd data found\n"); + if (ctx->draft_version_2) + { + log_info ("draft version 2 requested\n"); + flags |= WKS_RECEIVE_DRAFT2; + } + + if (ctx->plaintext) + { + if (opt.verbose) + log_info ("parsing decrypted message\n"); + plaintext = ctx->plaintext; + ctx->plaintext = NULL; + if (ctx->encrypted) + es_rewind (ctx->encrypted); + if (ctx->signeddata) + es_rewind (ctx->signeddata); + if (ctx->signature) + es_rewind (ctx->signature); + err = mime_parser_parse (parser, plaintext); + if (err) + return err; + } + + if (!ctx->key_data && !ctx->wkd_data) + { + log_error ("no suitable data found in the message\n"); + err = gpg_error (GPG_ERR_NO_DATA); + goto leave; + } + + if (ctx->key_data) + { + if (DBG_MIME) + { + es_rewind (ctx->key_data); + log_debug ("Key: '"); + log_printf ("\n"); + while ((c = es_getc (ctx->key_data)) != EOF) + log_printf ("%c", c); + log_printf ("'\n"); + } + if (result_cb) + { + es_rewind (ctx->key_data); + err = result_cb (cb_data, "application/pgp-keys", + ctx->key_data, flags); + if (err) + goto leave; + } + } + if (ctx->wkd_data) + { + if (DBG_MIME) + { + es_rewind (ctx->wkd_data); + log_debug ("WKD: '"); + log_printf ("\n"); + while ((c = es_getc (ctx->wkd_data)) != EOF) + log_printf ("%c", c); + log_printf ("'\n"); + } + if (result_cb) + { + es_rewind (ctx->wkd_data); + err = result_cb (cb_data, "application/vnd.gnupg.wks", + ctx->wkd_data, flags); + if (err) + goto leave; + } + } + + + leave: + es_fclose (plaintext); + mime_parser_release (parser); + ctx->parser = NULL; + es_fclose (ctx->encrypted); + es_fclose (ctx->plaintext); + es_fclose (ctx->signeddata); + es_fclose (ctx->signature); + es_fclose (ctx->key_data); + es_fclose (ctx->wkd_data); + xfree (ctx); + return err; +} |