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    1 /*
    2  *  Project   : tin - a Usenet reader
    3  *  Module    : pgp.c
    4  *  Author    : Steven J. Madsen
    5  *  Created   : 1995-05-12
    6  *  Updated   : 2021-02-27
    7  *  Notes     : PGP support
    8  *
    9  * Copyright (c) 1995-2022 Steven J. Madsen <steve@erinet.com>
   10  * All rights reserved.
   11  *
   12  * Redistribution and use in source and binary forms, with or without
   13  * modification, are permitted provided that the following conditions
   14  * are met:
   15  *
   16  * 1. Redistributions of source code must retain the above copyright notice,
   17  *    this list of conditions and the following disclaimer.
   18  *
   19  * 2. Redistributions in binary form must reproduce the above copyright
   20  *    notice, this list of conditions and the following disclaimer in the
   21  *    documentation and/or other materials provided with the distribution.
   22  *
   23  * 3. Neither the name of the copyright holder nor the names of its
   24  *    contributors may be used to endorse or promote products derived from
   25  *    this software without specific prior written permission.
   26  *
   27  * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   28  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   30  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
   31  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   32  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   33  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   34  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   35  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   36  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   37  * POSSIBILITY OF SUCH DAMAGE.
   38  */
   39 
   40 
   41 #ifndef TIN_H
   42 #   include "tin.h"
   43 #endif /* !TIN_H */
   44 
   45 #ifdef HAVE_PGP_GPG
   46 #   ifndef TCURSES_H
   47 #       include "tcurses.h"
   48 #   endif /* !TCURSES_H */
   49 
   50 
   51 /*
   52  * The first two args are typically the PGP command name and then $PGPOPTS
   53  * NB: The '1' variations on DO_{SIGN,BOTH} are used when local-user name is
   54  * used and are valid only when signing
   55  */
   56 #   if defined(HAVE_PGP) /* pgp-2 */
   57 #       define PGPNAME      PATH_PGP
   58 #       define PGPDIR       ".pgp"
   59 #       define PGP_PUBRING  "pubring.pgp"
   60 #       define CHECK_SIGN   "%s %s -f <%s %s"
   61 #       define ADD_KEY      "%s %s -ka %s"
   62 #       define APPEND_KEY   "%s %s -kxa %s %s", PGPNAME, pgpopts, buf, keyfile
   63 #       define DO_ENCRYPT   "%s %s -ate %s %s", PGPNAME, pgpopts, pt, mailto
   64 #       define DO_SIGN      "%s %s -ats %s %s", PGPNAME, pgpopts, pt, mailto
   65 #       define DO_SIGN1     "%s %s -ats %s %s -u %s", PGPNAME, pgpopts, pt, mailto, mailfrom
   66 #       define DO_BOTH      "%s %s -ates %s %s", PGPNAME, pgpopts, pt, mailto
   67 #       define DO_BOTH1     "%s %s -ates %s %s -u %s", PGPNAME, pgpopts, pt, mailto, mailfrom
   68 #   endif /* HAVE_PGP */
   69 
   70 #   if defined(HAVE_PGPK) /* pgp-5 */
   71 #       define PGPNAME      "pgp"   /* FIXME: this is AFAIK not PATH_PGPK */
   72 #       define PGPDIR       ".pgp"
   73 #       define PGP_PUBRING  "pubring.pkr"
   74 #       define CHECK_SIGN   "%sv %s -f <%s %s"
   75 #       define ADD_KEY      "%sk %s -a %s"
   76 #       define APPEND_KEY   "%sk %s -xa %s -o %s", PGPNAME, pgpopts, keyfile, buf
   77 #       define DO_ENCRYPT   "%se %s -at %s %s", PGPNAME, pgpopts, pt, mailto
   78 #       define DO_SIGN      "%ss %s -at %s %s", PGPNAME, pgpopts, pt, mailto
   79 #       define DO_SIGN1     "%ss %s -at %s %s -u %s", PGPNAME, pgpopts, pt, mailto, mailfrom
   80 #       define DO_BOTH      "%se %s -ats %s %s", PGPNAME, pgpopts, pt, mailto
   81 #       define DO_BOTH1     "%se %s -ats %s %s -u %s", PGPNAME, pgpopts, pt, mailto, mailfrom
   82 #   endif /* HAVE_PGPK */
   83 
   84 #   if defined(HAVE_GPG) /* gpg */
   85 #       define PGPNAME      PATH_GPG
   86 #       define PGPDIR       ".gnupg"
   87 #       define PGP_PUBRING  "pubring.gpg"
   88 #       if 0 /* gpg 1.4.11 doesn't like this */
   89 #           define CHECK_SIGN   "%s %s --no-batch --decrypt <%s %s"
   90 #       else
   91 #           define CHECK_SIGN   "%s %s < %s %s"
   92 #       endif /* 0 */
   93 #       define ADD_KEY      "%s %s --no-batch --import %s"
   94 #       define APPEND_KEY   "%s %s --no-batch --armor --output %s --export %s", PGPNAME, pgpopts, keyfile, buf
   95 #       define DO_ENCRYPT   \
   96 "%s %s --textmode --armor --no-batch --output %s.asc --recipient %s --encrypt %s", \
   97 PGPNAME, pgpopts, pt, mailto, pt
   98 #       define DO_SIGN      \
   99 "%s %s --textmode --armor --no-batch --output %s.asc --escape-from --clearsign %s", \
  100 PGPNAME, pgpopts, pt, pt
  101 #       define DO_SIGN1     \
  102 "%s %s --textmode --armor --no-batch --local-user %s --output %s.asc --escape-from --clearsign %s", \
  103 PGPNAME, pgpopts, mailfrom, pt, pt
  104 #       define DO_BOTH      \
  105 "%s %s --textmode --armor --no-batch --output %s.asc --recipient %s --sign --encrypt %s", \
  106 PGPNAME, pgpopts, pt, mailto, pt
  107 #       define DO_BOTH1     \
  108 "%s %s --textmode --armor --no-batch --output %s.asc --recipient %s --local-user %s --sign --encrypt %s", \
  109 PGPNAME, pgpopts, pt, mailto, mailfrom, pt
  110 #   endif /* HAVE_GPG */
  111 
  112 /* RFC 4880 6.2 */
  113 #   define PGP_SIG_TAG "-----BEGIN PGP SIGNED MESSAGE-----\n"
  114 #   define PGP_KEY_TAG "-----BEGIN PGP PUBLIC KEY BLOCK-----\n"
  115 
  116 #   define HEADERS  "tin-%ld.h"
  117 #   ifdef HAVE_LONG_FILE_NAMES
  118 #       define PLAINTEXT    "tin-%ld.pt"
  119 #       define CIPHERTEXT   "tin-%ld.pt.asc"
  120 #       define KEYFILE      "tin-%ld.k.asc"
  121 #   else
  122 #       define PLAINTEXT    "tn-%ld.p"
  123 #       define CIPHERTEXT   "tn-%ld.p.asc"
  124 #       define KEYFILE      "tn-%ld.k.asc"
  125 #   endif /* HAVE_LONG_FILE_NAMES */
  126 
  127 
  128 /*
  129  * local prototypes
  130  */
  131 static t_bool pgp_available(void);
  132 static void do_pgp(t_function what, const char *file, const char *mail_to);
  133 static void join_files(const char *file);
  134 static void pgp_append_public_key(char *file);
  135 static void split_file(const char *file);
  136 
  137 static char pgp_data[PATH_LEN];
  138 static char hdr[PATH_LEN], pt[PATH_LEN], ct[PATH_LEN];
  139 static const char *pgpopts = "";
  140 
  141 
  142 void
  143 init_pgp(
  144     void)
  145 {
  146     char *ptr;
  147 
  148     pgpopts = get_val("PGPOPTS", "");
  149 
  150 #   ifdef HAVE_GPG
  151     if ((ptr = getenv("GNUPGHOME")) != NULL)
  152         my_strncpy(pgp_data, ptr, sizeof(pgp_data) - 1);
  153     else
  154 #   endif /* HAVE_GPG */
  155     {
  156         if ((ptr = getenv("PGPPATH")) != NULL)
  157             my_strncpy(pgp_data, ptr, sizeof(pgp_data) - 1);
  158         else
  159             joinpath(pgp_data, sizeof(pgp_data), homedir, PGPDIR);
  160     }
  161 }
  162 
  163 
  164 /*
  165  * Write the header file then the ciphertext file to the art file
  166  * This function is void, no way to return errs
  167  */
  168 static void
  169 join_files(
  170     const char *file)
  171 {
  172     FILE *art, *header, *text;
  173 
  174     if ((header = fopen(hdr, "r")) != NULL) {
  175         if ((text = fopen(ct, "r")) != NULL) {
  176             if ((art = fopen(file, "w")) != NULL) {
  177                 if (copy_fp(header, art))
  178                     copy_fp(text, art);
  179                 fclose(art);
  180             }
  181             fclose(text);
  182         }
  183         fclose(header);
  184     }
  185 
  186     unlink(hdr);
  187     unlink(pt);
  188     unlink(ct);
  189 }
  190 
  191 
  192 /*
  193  * Split the file parameter into a header file 'hdr' and a plaintext
  194  * file 'pt'
  195  */
  196 static void
  197 split_file(
  198     const char *file)
  199 {
  200     FILE *art, *header, *plaintext;
  201     char buf[LEN];
  202     char tmp[PATH_LEN];
  203     mode_t mask;
  204 
  205     snprintf(tmp, sizeof(tmp), HEADERS, (long) process_id);
  206     joinpath(hdr, sizeof(hdr), TMPDIR, tmp);
  207     snprintf(tmp, sizeof(tmp), PLAINTEXT, (long) process_id);
  208     joinpath(pt, sizeof(pt), TMPDIR, tmp);
  209     snprintf(tmp, sizeof(tmp), CIPHERTEXT, (long) process_id);
  210     joinpath(ct, sizeof(ct), TMPDIR, tmp);
  211 
  212     if ((art = fopen(file, "r")) == NULL)
  213         return;
  214 
  215     mask = umask((mode_t) (S_IRWXO|S_IRWXG));
  216 
  217     if ((header = fopen(hdr, "w")) == NULL)
  218         goto err_art;
  219 
  220     if ((plaintext = fopen(pt, "w")) == NULL)
  221         goto err_hdr;
  222 
  223     if (fgets(buf, LEN, art) != NULL) {         /* Copy the hdr up to and including the \n */
  224         while (strcmp(buf, "\n")) {
  225             fputs(buf, header);
  226             fgets(buf, LEN, art);
  227         }
  228         fputs(buf, header);
  229         copy_fp(art, plaintext);
  230     }
  231 
  232     fclose(plaintext);
  233 err_hdr:
  234     fclose(header);
  235 err_art:
  236     fclose(art);
  237     umask(mask);
  238 }
  239 
  240 
  241 static void
  242 do_pgp(
  243     t_function what,
  244     const char *file,
  245     const char *mail_to)
  246 {
  247     char cmd[LEN];
  248     char mailfrom[LEN];
  249     const char *mailto = BlankIfNull(mail_to);
  250 
  251     mailfrom[0] = '\0';
  252 
  253     split_file(file);
  254 
  255     /*
  256      * <mailfrom> is valid only when signing and a local address exists
  257      */
  258     if ((CURR_GROUP.attribute->from) != NULL)
  259         strip_name(CURR_GROUP.attribute->from, mailfrom);
  260 
  261     switch (what) {
  262         case PGP_KEY_SIGN:
  263             if (strlen(mailfrom))
  264                 sh_format(cmd, sizeof(cmd), DO_SIGN1);
  265             else
  266                 sh_format(cmd, sizeof(cmd), DO_SIGN);
  267             invoke_cmd(cmd);
  268             break;
  269 
  270         case PGP_KEY_ENCRYPT_SIGN:
  271             if (strlen(mailfrom))
  272                 sh_format(cmd, sizeof(cmd), DO_BOTH1);
  273             else
  274                 sh_format(cmd, sizeof(cmd), DO_BOTH);
  275             invoke_cmd(cmd);
  276             break;
  277 
  278         case PGP_KEY_ENCRYPT:
  279             sh_format(cmd, sizeof(cmd), DO_ENCRYPT);
  280             invoke_cmd(cmd);
  281             break;
  282 
  283         default:
  284             break;
  285     }
  286 
  287     join_files(file);
  288 }
  289 
  290 
  291 static void
  292 pgp_append_public_key(
  293     char *file)
  294 {
  295     FILE *fp, *key;
  296     char cmd[LEN], buf[LEN];
  297     char keyfile[PATH_LEN], tmp[PATH_LEN];
  298 
  299     if ((CURR_GROUP.attribute->from) != NULL && strlen(CURR_GROUP.attribute->from))
  300         strip_name(CURR_GROUP.attribute->from, buf);
  301     else
  302         snprintf(buf, sizeof(buf), "%s@%s", userid, BlankIfNull(get_host_name()));
  303 
  304     snprintf(tmp, sizeof(tmp), KEYFILE, (long) process_id);
  305     joinpath(keyfile, sizeof(keyfile), TMPDIR, tmp);
  306 
  307 /*
  308  * TODO: I'm guessing the pgp append key command creates 'keyfile' and that
  309  * we should remove it
  310  */
  311     sh_format(cmd, sizeof(cmd), APPEND_KEY);
  312     if (invoke_cmd(cmd)) {
  313         if ((fp = fopen(file, "a")) != NULL) {
  314             if ((key = fopen(keyfile, "r")) != NULL) {
  315                 fputc('\n', fp);            /* Add a blank line */
  316                 copy_fp(key, fp);           /* and copy in the key */
  317                 fclose(key);
  318             }
  319             fclose(fp);
  320         }
  321         unlink(keyfile);
  322     }
  323 }
  324 
  325 
  326 /*
  327  * Simply check for existence of keyring file
  328  */
  329 static t_bool
  330 pgp_available(
  331     void)
  332 {
  333     FILE *fp;
  334     char keyring[PATH_LEN];
  335 
  336     joinpath(keyring, sizeof(keyring), pgp_data, PGP_PUBRING);
  337     if ((fp = fopen(keyring, "r")) == NULL) {
  338         wait_message(2, _(txt_pgp_not_avail), keyring);
  339         return FALSE;
  340     }
  341 
  342     fclose(fp);
  343     return TRUE;
  344 }
  345 
  346 
  347 void
  348 invoke_pgp_mail(
  349     const char *nam,
  350     char *mail_to)
  351 {
  352     char keyboth[MAXKEYLEN], keyencrypt[MAXKEYLEN], keyquit[MAXKEYLEN];
  353     char keysign[MAXKEYLEN];
  354     t_function func, default_func = PGP_KEY_SIGN;
  355 
  356     if (!pgp_available())
  357         return;
  358 
  359     func = prompt_slk_response(default_func, pgp_mail_keys, _(txt_pgp_mail),
  360             PrintFuncKey(keyencrypt, PGP_KEY_ENCRYPT, pgp_mail_keys),
  361             PrintFuncKey(keysign, PGP_KEY_SIGN, pgp_mail_keys),
  362             PrintFuncKey(keyboth, PGP_KEY_ENCRYPT_SIGN, pgp_mail_keys),
  363             PrintFuncKey(keyquit, GLOBAL_QUIT, pgp_mail_keys));
  364     switch (func) {
  365         case PGP_KEY_SIGN:
  366 #   ifdef HAVE_PGPK
  367             ClearScreen();
  368             MoveCursor(cLINES - 7, 0);
  369 #   endif /* HAVE_PGPK */
  370             do_pgp(func, nam, NULL);
  371             break;
  372 
  373         case PGP_KEY_ENCRYPT_SIGN:
  374 #   ifdef HAVE_PGPK
  375             ClearScreen();
  376             MoveCursor(cLINES - 7, 0);
  377 #   endif /* HAVE_PGPK */
  378             do_pgp(func, nam, mail_to);
  379             break;
  380 
  381         case PGP_KEY_ENCRYPT:
  382             do_pgp(func, nam, mail_to);
  383             break;
  384 
  385         case GLOBAL_ABORT:
  386         case GLOBAL_QUIT:
  387         default:
  388             break;
  389     }
  390 }
  391 
  392 
  393 void
  394 invoke_pgp_news(
  395     char *artfile)
  396 {
  397     char keyinclude[MAXKEYLEN], keyquit[MAXKEYLEN], keysign[MAXKEYLEN];
  398     t_function func, default_func = PGP_KEY_SIGN;
  399 
  400     if (!pgp_available())
  401         return;
  402 
  403     func = prompt_slk_response(default_func, pgp_news_keys, _(txt_pgp_news),
  404                 PrintFuncKey(keysign, PGP_KEY_SIGN, pgp_news_keys),
  405                 PrintFuncKey(keyinclude, PGP_INCLUDE_KEY, pgp_news_keys),
  406                 PrintFuncKey(keyquit, GLOBAL_QUIT, pgp_news_keys));
  407     switch (func) {
  408         case GLOBAL_ABORT:
  409         case GLOBAL_QUIT:
  410             break;
  411 
  412         case PGP_KEY_SIGN:
  413 #   ifdef HAVE_PGPK
  414             info_message(" ");
  415             MoveCursor(cLINES - 7, 0);
  416             my_printf("\n");
  417 #   endif /* HAVE_PGPK */
  418             do_pgp(func, artfile, NULL);
  419             break;
  420 
  421         case PGP_INCLUDE_KEY:
  422 #   ifdef HAVE_PGPK
  423             info_message(" ");
  424             MoveCursor(cLINES - 7, 0);
  425             my_printf("\n");
  426 #   endif /* HAVE_PGPK */
  427             do_pgp(PGP_KEY_SIGN, artfile, NULL);
  428             pgp_append_public_key(artfile);
  429             break;
  430 
  431         default:
  432             break;
  433     }
  434 }
  435 
  436 
  437 t_bool
  438 pgp_check_article(
  439     t_openartinfo *artinfo)
  440 {
  441     FILE *art;
  442     char artfile[PATH_LEN], buf[LEN], cmd[LEN];
  443     t_bool pgp_signed = FALSE;
  444     t_bool pgp_key = FALSE;
  445 
  446     if (!pgp_available())
  447         return FALSE;
  448 
  449     joinpath(artfile, sizeof(artfile), homedir, TIN_ARTICLE_NAME);
  450 #   ifdef APPEND_PID
  451     snprintf(artfile + strlen(artfile), sizeof(artfile) - strlen(artfile), ".%ld", (long) process_id);
  452 #   endif /* APPEND_PID */
  453     if ((art = fopen(artfile, "w")) == NULL) {
  454         info_message(_(txt_cannot_open), artfile);
  455         return FALSE;
  456     }
  457     /* -> start of body */
  458     if (fseek(artinfo->raw, artinfo->hdr.ext->offset, SEEK_SET) != 0) {
  459         fclose(art);
  460         return FALSE;
  461     }
  462 
  463     if (fgets(buf, LEN, artinfo->raw) != NULL) {        /* Copy the body whilst looking for SIG/KEY tags */
  464         while (!feof(artinfo->raw)) {
  465             if (!pgp_signed && !strcmp(buf, PGP_SIG_TAG))
  466                 pgp_signed = TRUE;
  467             if (!pgp_key && !strcmp(buf, PGP_KEY_TAG))
  468                 pgp_key = TRUE;
  469             fputs(buf, art);
  470             fgets(buf, LEN, artinfo->raw);
  471         }
  472     }
  473     fclose(art);
  474 
  475     if (!(pgp_signed || pgp_key)) {
  476         info_message(_(txt_pgp_nothing));
  477         return FALSE;
  478     }
  479     ClearScreen();
  480 
  481     if (pgp_signed) {
  482         Raw(FALSE);
  483 
  484         /*
  485          * We don't use sh_format here else the redirection get misquoted
  486          */
  487         snprintf(cmd, sizeof(cmd), CHECK_SIGN, PGPNAME, pgpopts, artfile, REDIRECT_PGP_OUTPUT);
  488         invoke_cmd(cmd);
  489         my_printf("\n");
  490         Raw(TRUE);
  491     }
  492 #   ifndef USE_CURSES
  493     EndWin();
  494     Raw(FALSE);
  495 #   endif /* !USE_CURSES */
  496     prompt_continue();
  497 #   ifndef USE_CURSES
  498     Raw(TRUE);
  499     InitWin();
  500 #   endif /* !USE_CURSES */
  501     if (pgp_key) {
  502         if (prompt_yn(_(txt_pgp_add), FALSE) == 1) {
  503             Raw(FALSE);
  504 
  505             sh_format(cmd, sizeof(cmd), ADD_KEY, PGPNAME, pgpopts, artfile);
  506             invoke_cmd(cmd);
  507             my_printf("\n");
  508             Raw(TRUE);
  509         }
  510     }
  511 
  512     unlink(artfile);
  513     return TRUE;
  514 }
  515 #endif /* HAVE_PGP_GPG */