diff options
Diffstat (limited to 'agent/trustlist.c')
| -rw-r--r-- | agent/trustlist.c | 763 |
1 files changed, 763 insertions, 0 deletions
diff --git a/agent/trustlist.c b/agent/trustlist.c new file mode 100644 index 0000000..be5406b --- /dev/null +++ b/agent/trustlist.c @@ -0,0 +1,763 @@ +/* trustlist.c - Maintain the list of trusted keys + * Copyright (C) 2002, 2004, 2006, 2007, 2009 Free Software Foundation, Inc. + * + * This file is part of GnuPG. + * + * GnuPG 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 3 of the License, or + * (at your option) any later version. + * + * GnuPG 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, see <http://www.gnu.org/licenses/>. + */ + +#include <config.h> +#include <errno.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <ctype.h> +#include <assert.h> +#include <unistd.h> +#include <sys/stat.h> +#include <pth.h> + +#include "agent.h" +#include <assuan.h> /* fixme: need a way to avoid assuan calls here */ +#include "i18n.h" +#include "estream.h" + + +/* A structure to store the information from the trust file. */ +struct trustitem_s +{ + struct + { + int disabled:1; /* This entry is disabled. */ + int for_pgp:1; /* Set by '*' or 'P' as first flag. */ + int for_smime:1; /* Set by '*' or 'S' as first flag. */ + int relax:1; /* Relax checking of root certificate + constraints. */ + int cm:1; /* Use chain model for validation. */ + } flags; + unsigned char fpr[20]; /* The binary fingerprint. */ +}; +typedef struct trustitem_s trustitem_t; + +/* Malloced table and its allocated size with all trust items. */ +static trustitem_t *trusttable; +static size_t trusttablesize; +/* A mutex used to protect the table. */ +static pth_mutex_t trusttable_lock; + + + +static const char headerblurb[] = +"# This is the list of trusted keys. Comment lines, like this one, as\n" +"# well as empty lines are ignored. Lines have a length limit but this\n" +"# is not a serious limitation as the format of the entries is fixed and\n" +"# checked by gpg-agent. A non-comment line starts with optional white\n" +"# space, followed by the SHA-1 fingerpint in hex, followed by a flag\n" +"# which may be one of 'P', 'S' or '*' and optionally followed by a list of\n" +"# other flags. The fingerprint may be prefixed with a '!' to mark the\n" +"# key as not trusted. You should give the gpg-agent a HUP or run the\n" +"# command \"gpgconf --reload gpg-agent\" after changing this file.\n" +"\n\n" +"# Include the default trust list\n" +"include-default\n" +"\n"; + + +/* This function must be called once to initialize this module. This + has to be done before a second thread is spawned. We can't do the + static initialization because Pth emulation code might not be able + to do a static init; in particular, it is not possible for W32. */ +void +initialize_module_trustlist (void) +{ + static int initialized; + + if (!initialized) + { + if (!pth_mutex_init (&trusttable_lock)) + log_fatal ("error initializing mutex: %s\n", strerror (errno)); + initialized = 1; + } +} + + + + +static void +lock_trusttable (void) +{ + if (!pth_mutex_acquire (&trusttable_lock, 0, NULL)) + log_fatal ("failed to acquire mutex in %s\n", __FILE__); +} + +static void +unlock_trusttable (void) +{ + if (!pth_mutex_release (&trusttable_lock)) + log_fatal ("failed to release mutex in %s\n", __FILE__); +} + + + +static gpg_error_t +read_one_trustfile (const char *fname, int allow_include, + trustitem_t **addr_of_table, + size_t *addr_of_tablesize, + int *addr_of_tableidx) +{ + gpg_error_t err = 0; + FILE *fp; + int n, c; + char *p, line[256]; + trustitem_t *table, *ti; + int tableidx; + size_t tablesize; + int lnr = 0; + + table = *addr_of_table; + tablesize = *addr_of_tablesize; + tableidx = *addr_of_tableidx; + + fp = fopen (fname, "r"); + if (!fp) + { + err = gpg_error_from_syserror (); + log_error (_("error opening `%s': %s\n"), fname, gpg_strerror (err)); + goto leave; + } + + while (fgets (line, DIM(line)-1, fp)) + { + lnr++; + + if (!*line || line[strlen(line)-1] != '\n') + { + /* Eat until end of line. */ + while ( (c=getc (fp)) != EOF && c != '\n') + ; + err = gpg_error (*line? GPG_ERR_LINE_TOO_LONG + : GPG_ERR_INCOMPLETE_LINE); + log_error (_("file `%s', line %d: %s\n"), + fname, lnr, gpg_strerror (err)); + continue; + } + line[strlen(line)-1] = 0; /* Chop the LF. */ + + /* Allow for empty lines and spaces */ + for (p=line; spacep (p); p++) + ; + if (!*p || *p == '#') + continue; + + if (!strncmp (p, "include-default", 15) + && (!p[15] || spacep (p+15))) + { + char *etcname; + gpg_error_t err2; + + if (!allow_include) + { + log_error (_("statement \"%s\" ignored in `%s', line %d\n"), + "include-default", fname, lnr); + continue; + } + /* fixme: Should check for trailing garbage. */ + + etcname = make_filename (gnupg_sysconfdir (), "trustlist.txt", NULL); + if ( !strcmp (etcname, fname) ) /* Same file. */ + log_info (_("statement \"%s\" ignored in `%s', line %d\n"), + "include-default", fname, lnr); + else if ( access (etcname, F_OK) && errno == ENOENT ) + { + /* A non existent system trustlist is not an error. + Just print a note. */ + log_info (_("system trustlist `%s' not available\n"), etcname); + } + else + { + err2 = read_one_trustfile (etcname, 0, + &table, &tablesize, &tableidx); + if (err2) + err = err2; + } + xfree (etcname); + + continue; + } + + if (tableidx == tablesize) /* Need more space. */ + { + trustitem_t *tmp; + size_t tmplen; + + tmplen = tablesize + 20; + tmp = xtryrealloc (table, tmplen * sizeof *table); + if (!tmp) + { + err = gpg_error_from_syserror (); + goto leave; + } + table = tmp; + tablesize = tmplen; + } + + ti = table + tableidx; + + memset (&ti->flags, 0, sizeof ti->flags); + if (*p == '!') + { + ti->flags.disabled = 1; + p++; + while (spacep (p)) + p++; + } + + n = hexcolon2bin (p, ti->fpr, 20); + if (n < 0) + { + log_error (_("bad fingerprint in `%s', line %d\n"), fname, lnr); + err = gpg_error (GPG_ERR_BAD_DATA); + continue; + } + p += n; + for (; spacep (p); p++) + ; + + /* Process the first flag which needs to be the first for + backward compatibility. */ + if (!*p || *p == '*' ) + { + ti->flags.for_smime = 1; + ti->flags.for_pgp = 1; + } + else if ( *p == 'P' || *p == 'p') + { + ti->flags.for_pgp = 1; + } + else if ( *p == 'S' || *p == 's') + { + ti->flags.for_smime = 1; + } + else + { + log_error (_("invalid keyflag in `%s', line %d\n"), fname, lnr); + err = gpg_error (GPG_ERR_BAD_DATA); + continue; + } + p++; + if ( *p && !spacep (p) ) + { + log_error (_("invalid keyflag in `%s', line %d\n"), fname, lnr); + err = gpg_error (GPG_ERR_BAD_DATA); + continue; + } + + /* Now check for more key-value pairs of the form NAME[=VALUE]. */ + while (*p) + { + for (; spacep (p); p++) + ; + if (!*p) + break; + n = strcspn (p, "= \t"); + if (p[n] == '=') + { + log_error ("assigning a value to a flag is not yet supported; " + "in `%s', line %d\n", fname, lnr); + err = gpg_error (GPG_ERR_BAD_DATA); + p++; + } + else if (n == 5 && !memcmp (p, "relax", 5)) + ti->flags.relax = 1; + else if (n == 2 && !memcmp (p, "cm", 2)) + ti->flags.cm = 1; + else + log_error ("flag `%.*s' in `%s', line %d ignored\n", + n, p, fname, lnr); + p += n; + } + tableidx++; + } + if ( !err && !feof (fp) ) + { + err = gpg_error_from_syserror (); + log_error (_("error reading `%s', line %d: %s\n"), + fname, lnr, gpg_strerror (err)); + } + + leave: + if (fp) + fclose (fp); + *addr_of_table = table; + *addr_of_tablesize = tablesize; + *addr_of_tableidx = tableidx; + return err; +} + + +/* Read the trust files and update the global table on success. */ +static gpg_error_t +read_trustfiles (void) +{ + gpg_error_t err; + trustitem_t *table, *ti; + int tableidx; + size_t tablesize; + char *fname; + int allow_include = 1; + + tablesize = 20; + table = xtrycalloc (tablesize, sizeof *table); + if (!table) + return gpg_error_from_syserror (); + tableidx = 0; + + fname = make_filename (opt.homedir, "trustlist.txt", NULL); + if ( access (fname, F_OK) ) + { + if ( errno == ENOENT ) + ; /* Silently ignore a non-existing trustfile. */ + else + { + err = gpg_error_from_syserror (); + log_error (_("error opening `%s': %s\n"), fname, gpg_strerror (err)); + } + xfree (fname); + fname = make_filename (gnupg_sysconfdir (), "trustlist.txt", NULL); + allow_include = 0; + } + err = read_one_trustfile (fname, allow_include, + &table, &tablesize, &tableidx); + xfree (fname); + + if (err) + { + xfree (table); + if (gpg_err_code (err) == GPG_ERR_ENOENT) + { + /* Take a missing trustlist as an empty one. */ + lock_trusttable (); + xfree (trusttable); + trusttable = NULL; + trusttablesize = 0; + unlock_trusttable (); + err = 0; + } + return err; + } + + /* Fixme: we should drop duplicates and sort the table. */ + ti = xtryrealloc (table, (tableidx?tableidx:1) * sizeof *table); + if (!ti) + { + err = gpg_error_from_syserror (); + xfree (table); + return err; + } + + lock_trusttable (); + xfree (trusttable); + trusttable = ti; + trusttablesize = tableidx; + unlock_trusttable (); + return 0; +} + + + +/* Check whether the given fpr is in our trustdb. We expect FPR to be + an all uppercase hexstring of 40 characters. */ +gpg_error_t +agent_istrusted (ctrl_t ctrl, const char *fpr, int *r_disabled) +{ + gpg_error_t err; + trustitem_t *ti; + size_t len; + unsigned char fprbin[20]; + + if (r_disabled) + *r_disabled = 0; + + if ( hexcolon2bin (fpr, fprbin, 20) < 0 ) + return gpg_error (GPG_ERR_INV_VALUE); + + if (!trusttable) + { + err = read_trustfiles (); + if (err) + { + log_error (_("error reading list of trusted root certificates\n")); + return err; + } + } + + if (trusttable) + { + for (ti=trusttable, len = trusttablesize; len; ti++, len--) + if (!memcmp (ti->fpr, fprbin, 20)) + { + if (ti->flags.disabled && r_disabled) + *r_disabled = 1; + + if (ti->flags.relax) + { + err = agent_write_status (ctrl, + "TRUSTLISTFLAG", "relax", + NULL); + if (err) + return err; + } + else if (ti->flags.cm) + { + err = agent_write_status (ctrl, + "TRUSTLISTFLAG", "cm", + NULL); + if (err) + return err; + } + return ti->flags.disabled? gpg_error (GPG_ERR_NOT_TRUSTED) : 0; + } + } + return gpg_error (GPG_ERR_NOT_TRUSTED); +} + + +/* Write all trust entries to FP. */ +gpg_error_t +agent_listtrusted (void *assuan_context) +{ + trustitem_t *ti; + char key[51]; + gpg_error_t err; + size_t len; + + if (!trusttable) + { + err = read_trustfiles (); + if (err) + { + log_error (_("error reading list of trusted root certificates\n")); + return err; + } + } + + if (trusttable) + { + /* We need to lock the table because the scheduler may interrupt + assuan_send_data and an other thread may then re-read the table. */ + lock_trusttable (); + for (ti=trusttable, len = trusttablesize; len; ti++, len--) + { + if (ti->flags.disabled) + continue; + bin2hex (ti->fpr, 20, key); + key[40] = ' '; + key[41] = ((ti->flags.for_smime && ti->flags.for_pgp)? '*' + : ti->flags.for_smime? 'S': ti->flags.for_pgp? 'P':' '); + key[42] = '\n'; + assuan_send_data (assuan_context, key, 43); + assuan_send_data (assuan_context, NULL, 0); /* flush */ + } + unlock_trusttable (); + } + + return 0; +} + + +/* Create a copy of string with colons inserted after each two bytes. + Caller needs to release the string. In case of a memory failure, + NULL is returned. */ +static char * +insert_colons (const char *string) +{ + char *buffer, *p; + size_t n = strlen (string); + size_t nnew = n + (n+1)/2; + + p = buffer = xtrymalloc ( nnew + 1 ); + if (!buffer) + return NULL; + while (*string) + { + *p++ = *string++; + if (*string) + { + *p++ = *string++; + if (*string) + *p++ = ':'; + } + } + *p = 0; + assert (strlen (buffer) <= nnew); + + return buffer; +} + + +/* To pretty print DNs in the Pinentry, we replace slashes by + REPLSTRING. The caller needs to free the returned string. NULL is + returned on error with ERRNO set. */ +static char * +reformat_name (const char *name, const char *replstring) +{ + const char *s; + char *newname; + char *d; + size_t count; + size_t replstringlen = strlen (replstring); + + /* If the name does not start with a slash it is not a preformatted + DN and thus we don't bother to reformat it. */ + if (*name != '/') + return xtrystrdup (name); + + /* Count the names. Note that a slash contained in a DN part is + expected to be C style escaped and thus the slashes we see here + are the actual part delimiters. */ + for (s=name+1, count=0; *s; s++) + if (*s == '/') + count++; + newname = xtrymalloc (strlen (name) + count*replstringlen + 1); + if (!newname) + return NULL; + for (s=name+1, d=newname; *s; s++) + if (*s == '/') + d = stpcpy (d, replstring); + else + *d++ = *s; + *d = 0; + return newname; +} + + +/* Insert the given fpr into our trustdb. We expect FPR to be an all + uppercase hexstring of 40 characters. FLAG is either 'P' or 'C'. + This function does first check whether that key has already been put + into the trustdb and returns success in this case. Before a FPR + actually gets inserted, the user is asked by means of the Pinentry + whether this is actual want he wants to do. */ +gpg_error_t +agent_marktrusted (ctrl_t ctrl, const char *name, const char *fpr, int flag) +{ + gpg_error_t err = 0; + char *desc; + char *fname; + estream_t fp; + char *fprformatted; + char *nameformatted; + int is_disabled; + int yes_i_trust; + + /* Check whether we are at all allowed to modify the trustlist. + This is useful so that the trustlist may be a symlink to a global + trustlist with only admin priviliges to modify it. Of course + this is not a secure way of denying access, but it avoids the + usual clicking on an Okay button most users are used to. */ + fname = make_filename (opt.homedir, "trustlist.txt", NULL); + if ( access (fname, W_OK) && errno != ENOENT) + { + xfree (fname); + return gpg_error (GPG_ERR_EPERM); + } + xfree (fname); + + if (!agent_istrusted (ctrl, fpr, &is_disabled)) + { + return 0; /* We already got this fingerprint. Silently return + success. */ + } + + /* This feature must explicitly been enabled. */ + if (!opt.allow_mark_trusted) + return gpg_error (GPG_ERR_NOT_SUPPORTED); + + if (is_disabled) + { + /* There is an disabled entry in the trustlist. Return an error + so that the user won't be asked again for that one. Changing + this flag with the integrated marktrusted feature is and will + not be made possible. */ + return gpg_error (GPG_ERR_NOT_TRUSTED); + } + + + /* Insert a new one. */ + nameformatted = reformat_name (name, "%0A "); + if (!nameformatted) + return gpg_error_from_syserror (); + + /* First a general question whether this is trusted. */ + desc = xtryasprintf ( + /* TRANSLATORS: This prompt is shown by the Pinentry + and has one special property: A "%%0A" is used by + Pinentry to insert a line break. The double + percent sign is actually needed because it is also + a printf format string. If you need to insert a + plain % sign, you need to encode it as "%%25". The + "%s" gets replaced by the name as stored in the + certificate. */ + _("Do you ultimately trust%%0A" + " \"%s\"%%0A" + "to correctly certify user certificates?"), + nameformatted); + if (!desc) + { + xfree (nameformatted); + return out_of_core (); + } + err = agent_get_confirmation (ctrl, desc, _("Yes"), _("No"), 1); + xfree (desc); + if (!err) + yes_i_trust = 1; + else if (gpg_err_code (err) == GPG_ERR_NOT_CONFIRMED) + yes_i_trust = 0; + else + { + xfree (nameformatted); + return err; + } + + + fprformatted = insert_colons (fpr); + if (!fprformatted) + { + xfree (nameformatted); + return out_of_core (); + } + + /* If the user trusts this certificate he has to verify the + fingerprint of course. */ + if (yes_i_trust) + { + desc = xtryasprintf + ( + /* TRANSLATORS: This prompt is shown by the Pinentry and has + one special property: A "%%0A" is used by Pinentry to + insert a line break. The double percent sign is actually + needed because it is also a printf format string. If you + need to insert a plain % sign, you need to encode it as + "%%25". The second "%s" gets replaced by a hexdecimal + fingerprint string whereas the first one receives the name + as stored in the certificate. */ + _("Please verify that the certificate identified as:%%0A" + " \"%s\"%%0A" + "has the fingerprint:%%0A" + " %s"), nameformatted, fprformatted); + if (!desc) + { + xfree (fprformatted); + xfree (nameformatted); + return out_of_core (); + } + + /* TRANSLATORS: "Correct" is the label of a button and intended + to be hit if the fingerprint matches the one of the CA. The + other button is "the default "Cancel" of the Pinentry. */ + err = agent_get_confirmation (ctrl, desc, _("Correct"), _("Wrong"), 1); + xfree (desc); + if (gpg_err_code (err) == GPG_ERR_NOT_CONFIRMED) + yes_i_trust = 0; + else if (err) + { + xfree (fprformatted); + xfree (nameformatted); + return err; + } + } + + + /* Now check again to avoid duplicates. We take the lock to make + sure that nobody else plays with our file and force a reread. */ + lock_trusttable (); + agent_reload_trustlist (); + if (!agent_istrusted (ctrl, fpr, &is_disabled) || is_disabled) + { + unlock_trusttable (); + xfree (fprformatted); + xfree (nameformatted); + return is_disabled? gpg_error (GPG_ERR_NOT_TRUSTED) : 0; + } + + fname = make_filename (opt.homedir, "trustlist.txt", NULL); + if ( access (fname, F_OK) && errno == ENOENT) + { + fp = es_fopen (fname, "wx"); + if (!fp) + { + err = gpg_error_from_syserror (); + log_error ("can't create `%s': %s\n", fname, gpg_strerror (err)); + xfree (fname); + unlock_trusttable (); + xfree (fprformatted); + xfree (nameformatted); + return err; + } + es_fputs (headerblurb, fp); + es_fclose (fp); + } + fp = es_fopen (fname, "a+"); + if (!fp) + { + err = gpg_error_from_syserror (); + log_error ("can't open `%s': %s\n", fname, gpg_strerror (err)); + xfree (fname); + unlock_trusttable (); + xfree (fprformatted); + xfree (nameformatted); + return err; + } + + /* Append the key. */ + es_fputs ("\n# ", fp); + xfree (nameformatted); + nameformatted = reformat_name (name, "\n# "); + if (!nameformatted || strchr (name, '\n')) + { + /* Note that there should never be a LF in NAME but we better + play safe and print a sanitized version in this case. */ + es_write_sanitized (fp, name, strlen (name), NULL, NULL); + } + else + es_fputs (nameformatted, fp); + es_fprintf (fp, "\n%s%s %c\n", yes_i_trust?"":"!", fprformatted, flag); + if (es_ferror (fp)) + err = gpg_error_from_syserror (); + + if (es_fclose (fp)) + err = gpg_error_from_syserror (); + + agent_reload_trustlist (); + xfree (fname); + unlock_trusttable (); + xfree (fprformatted); + xfree (nameformatted); + return err; +} + + +/* This function may be called to force reloading of the + trustlist. */ +void +agent_reload_trustlist (void) +{ + /* All we need to do is to delete the trusttable. At the next + access it will get re-read. */ + lock_trusttable (); + xfree (trusttable); + trusttable = NULL; + trusttablesize = 0; + unlock_trusttable (); + bump_key_eventcounter (); +} |