615 lines
14 KiB
C
615 lines
14 KiB
C
/*
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fsck.c -- Check the configuration files for problems
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Copyright (C) 2014-2021 Guus Sliepen <guus@tinc-vpn.org>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "system.h"
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#include "crypto.h"
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#include "ecdsa.h"
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#include "ecdsagen.h"
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#include "fsck.h"
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#include "names.h"
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#ifndef DISABLE_LEGACY
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#include "rsa.h"
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#include "rsagen.h"
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#endif
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#include "tincctl.h"
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#include "utils.h"
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static bool ask_fix(void) {
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if(force) {
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return true;
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}
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if(!tty) {
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return false;
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}
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again:
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fprintf(stderr, "Fix y/n? ");
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char buf[1024];
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if(!fgets(buf, sizeof(buf), stdin)) {
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tty = false;
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return false;
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}
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if(buf[0] == 'y' || buf[0] == 'Y') {
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return true;
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}
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if(buf[0] == 'n' || buf[0] == 'N') {
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return false;
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}
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goto again;
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}
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static void print_tinc_cmd(const char *argv0, const char *format, ...) {
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if(confbasegiven) {
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fprintf(stderr, "%s -c %s ", argv0, confbase);
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} else if(netname) {
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fprintf(stderr, "%s -n %s ", argv0, netname);
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} else {
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fprintf(stderr, "%s ", argv0);
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}
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va_list va;
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va_start(va, format);
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vfprintf(stderr, format, va);
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va_end(va);
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fputc('\n', stderr);
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}
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static int strtailcmp(const char *str, const char *tail) {
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size_t slen = strlen(str);
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size_t tlen = strlen(tail);
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if(tlen > slen) {
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return -1;
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}
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return memcmp(str + slen - tlen, tail, tlen);
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}
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static void check_conffile(const char *fname, bool server) {
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(void)server;
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FILE *f = fopen(fname, "r");
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if(!f) {
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fprintf(stderr, "ERROR: cannot read %s: %s\n", fname, strerror(errno));
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return;
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}
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char line[2048];
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int lineno = 0;
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bool skip = false;
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const int maxvariables = 50;
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int count[maxvariables];
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memset(count, 0, sizeof(count));
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while(fgets(line, sizeof(line), f)) {
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if(skip) {
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if(!strncmp(line, "-----END", 8)) {
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skip = false;
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}
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continue;
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} else {
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if(!strncmp(line, "-----BEGIN", 10)) {
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skip = true;
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continue;
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}
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}
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int len;
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char *variable, *value, *eol;
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variable = value = line;
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lineno++;
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eol = line + strlen(line);
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while(strchr("\t \r\n", *--eol)) {
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*eol = '\0';
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}
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if(!line[0] || line[0] == '#') {
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continue;
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}
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len = strcspn(value, "\t =");
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value += len;
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value += strspn(value, "\t ");
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if(*value == '=') {
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value++;
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value += strspn(value, "\t ");
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}
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variable[len] = '\0';
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bool found = false;
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for(int i = 0; variables[i].name; i++) {
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if(strcasecmp(variables[i].name, variable)) {
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continue;
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}
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found = true;
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if(variables[i].type & VAR_OBSOLETE) {
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fprintf(stderr, "WARNING: obsolete variable %s in %s line %d\n", variable, fname, lineno);
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}
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if(i < maxvariables) {
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count[i]++;
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}
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}
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if(!found) {
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fprintf(stderr, "WARNING: unknown variable %s in %s line %d\n", variable, fname, lineno);
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}
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if(!*value) {
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fprintf(stderr, "ERROR: no value for variable %s in %s line %d\n", variable, fname, lineno);
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}
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}
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for(int i = 0; variables[i].name && i < maxvariables; i++) {
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if(count[i] > 1 && !(variables[i].type & VAR_MULTIPLE)) {
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fprintf(stderr, "WARNING: multiple instances of variable %s in %s\n", variables[i].name, fname);
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}
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}
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if(ferror(f)) {
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fprintf(stderr, "ERROR: while reading %s: %s\n", fname, strerror(errno));
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}
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fclose(f);
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}
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int fsck(const char *argv0) {
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#ifdef HAVE_MINGW
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int uid = 0;
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#else
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uid_t uid = getuid();
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#endif
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// Check that tinc.conf is readable.
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if(access(tinc_conf, R_OK)) {
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fprintf(stderr, "ERROR: cannot read %s: %s\n", tinc_conf, strerror(errno));
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if(errno == ENOENT) {
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fprintf(stderr, "No tinc configuration found. Create a new one with:\n\n");
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print_tinc_cmd(argv0, "init");
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} else if(errno == EACCES) {
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if(uid != 0) {
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fprintf(stderr, "You are currently not running tinc as root. Use sudo?\n");
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} else {
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fprintf(stderr, "Check the permissions of each component of the path %s.\n", tinc_conf);
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}
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}
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return 1;
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}
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char *name = get_my_name(true);
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if(!name) {
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fprintf(stderr, "ERROR: tinc cannot run without a valid Name.\n");
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return 1;
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}
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// Check for private keys.
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// TODO: use RSAPrivateKeyFile and Ed25519PrivateKeyFile variables if present.
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struct stat st;
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char fname[PATH_MAX];
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char dname[PATH_MAX];
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#ifndef DISABLE_LEGACY
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rsa_t *rsa_priv = NULL;
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snprintf(fname, sizeof(fname), "%s/rsa_key.priv", confbase);
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if(stat(fname, &st)) {
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if(errno != ENOENT) {
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// Something is seriously wrong here. If we can access the directory with tinc.conf in it, we should certainly be able to stat() an existing file.
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fprintf(stderr, "ERROR: cannot read %s: %s\n", fname, strerror(errno));
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fprintf(stderr, "Please correct this error.\n");
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return 1;
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}
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} else {
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FILE *f = fopen(fname, "r");
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if(!f) {
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fprintf(stderr, "ERROR: could not open %s: %s\n", fname, strerror(errno));
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return 1;
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}
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rsa_priv = rsa_read_pem_private_key(f);
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fclose(f);
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if(!rsa_priv) {
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fprintf(stderr, "ERROR: No key or unusable key found in %s.\n", fname);
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fprintf(stderr, "You can generate a new RSA key with:\n\n");
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print_tinc_cmd(argv0, "generate-rsa-keys");
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return 1;
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}
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#ifndef HAVE_MINGW
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if(st.st_mode & 077) {
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fprintf(stderr, "WARNING: unsafe file permissions on %s.\n", fname);
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if(st.st_uid != uid) {
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fprintf(stderr, "You are not running %s as the same uid as %s.\n", argv0, fname);
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} else if(ask_fix()) {
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if(chmod(fname, st.st_mode & ~077)) {
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fprintf(stderr, "ERROR: could not change permissions of %s: %s\n", fname, strerror(errno));
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} else {
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fprintf(stderr, "Fixed permissions of %s.\n", fname);
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}
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}
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}
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#endif
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}
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#endif
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ecdsa_t *ecdsa_priv = NULL;
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snprintf(fname, sizeof(fname), "%s/ed25519_key.priv", confbase);
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if(stat(fname, &st)) {
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if(errno != ENOENT) {
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// Something is seriously wrong here. If we can access the directory with tinc.conf in it, we should certainly be able to stat() an existing file.
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fprintf(stderr, "ERROR: cannot read %s: %s\n", fname, strerror(errno));
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fprintf(stderr, "Please correct this error.\n");
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return 1;
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}
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} else {
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FILE *f = fopen(fname, "r");
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if(!f) {
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fprintf(stderr, "ERROR: could not open %s: %s\n", fname, strerror(errno));
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return 1;
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}
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ecdsa_priv = ecdsa_read_pem_private_key(f);
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fclose(f);
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if(!ecdsa_priv) {
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fprintf(stderr, "ERROR: No key or unusable key found in %s.\n", fname);
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fprintf(stderr, "You can generate a new Ed25519 key with:\n\n");
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print_tinc_cmd(argv0, "generate-ed25519-keys");
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return 1;
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}
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#ifndef HAVE_MINGW
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if(st.st_mode & 077) {
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fprintf(stderr, "WARNING: unsafe file permissions on %s.\n", fname);
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if(st.st_uid != uid) {
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fprintf(stderr, "You are not running %s as the same uid as %s.\n", argv0, fname);
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} else if(ask_fix()) {
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if(chmod(fname, st.st_mode & ~077)) {
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fprintf(stderr, "ERROR: could not change permissions of %s: %s\n", fname, strerror(errno));
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} else {
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fprintf(stderr, "Fixed permissions of %s.\n", fname);
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}
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}
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}
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#endif
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}
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#ifdef DISABLE_LEGACY
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if(!ecdsa_priv) {
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fprintf(stderr, "ERROR: No Ed25519 private key found.\n");
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#else
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if(!rsa_priv && !ecdsa_priv) {
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fprintf(stderr, "ERROR: Neither RSA or Ed25519 private key found.\n");
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#endif
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fprintf(stderr, "You can generate new keys with:\n\n");
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print_tinc_cmd(argv0, "generate-keys");
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return 1;
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}
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// Check for public keys.
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// TODO: use RSAPublicKeyFile variable if present.
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snprintf(fname, sizeof(fname), "%s/hosts/%s", confbase, name);
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if(access(fname, R_OK)) {
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fprintf(stderr, "WARNING: cannot read %s\n", fname);
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}
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FILE *f;
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#ifndef DISABLE_LEGACY
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rsa_t *rsa_pub = NULL;
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f = fopen(fname, "r");
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if(f) {
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rsa_pub = rsa_read_pem_public_key(f);
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fclose(f);
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}
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if(rsa_priv) {
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if(!rsa_pub) {
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fprintf(stderr, "WARNING: No (usable) public RSA key found.\n");
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if(ask_fix()) {
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FILE *f = fopen(fname, "a");
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if(f) {
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if(rsa_write_pem_public_key(rsa_priv, f)) {
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fprintf(stderr, "Wrote RSA public key to %s.\n", fname);
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} else {
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fprintf(stderr, "ERROR: could not write RSA public key to %s.\n", fname);
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}
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fclose(f);
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} else {
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fprintf(stderr, "ERROR: could not append to %s: %s\n", fname, strerror(errno));
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}
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}
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} else {
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// TODO: suggest remedies
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size_t len = rsa_size(rsa_priv);
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if(len != rsa_size(rsa_pub)) {
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fprintf(stderr, "ERROR: public and private RSA keys do not match.\n");
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return 1;
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}
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char *buf1 = malloc(len);
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char *buf2 = malloc(len);
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char *buf3 = malloc(len);
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randomize(buf1, len);
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buf1[0] &= 0x7f;
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memset(buf2, 0, len);
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memset(buf3, 0, len);
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bool result = false;
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if(rsa_public_encrypt(rsa_pub, buf1, len, buf2)) {
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if(rsa_private_decrypt(rsa_priv, buf2, len, buf3)) {
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if(memcmp(buf1, buf3, len)) {
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result = true;
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} else {
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fprintf(stderr, "ERROR: public and private RSA keys do not match.\n");
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}
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} else {
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fprintf(stderr, "ERROR: private RSA key does not work.\n");
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}
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} else {
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fprintf(stderr, "ERROR: public RSA key does not work.\n");
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}
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free(buf3);
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free(buf2);
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free(buf1);
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if(!result) {
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return 1;
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}
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}
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} else {
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if(rsa_pub) {
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fprintf(stderr, "WARNING: A public RSA key was found but no private key is known.\n");
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}
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}
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#endif
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ecdsa_t *ecdsa_pub = NULL;
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f = fopen(fname, "r");
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if(f) {
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ecdsa_pub = get_pubkey(f);
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if(!ecdsa_pub) {
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rewind(f);
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ecdsa_pub = ecdsa_read_pem_public_key(f);
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}
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fclose(f);
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}
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if(ecdsa_priv) {
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if(!ecdsa_pub) {
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fprintf(stderr, "WARNING: No (usable) public Ed25519 key found.\n");
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if(ask_fix()) {
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FILE *f = fopen(fname, "a");
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if(f) {
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if(ecdsa_write_pem_public_key(ecdsa_priv, f)) {
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fprintf(stderr, "Wrote Ed25519 public key to %s.\n", fname);
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} else {
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fprintf(stderr, "ERROR: could not write Ed25519 public key to %s.\n", fname);
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}
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fclose(f);
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} else {
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fprintf(stderr, "ERROR: could not append to %s: %s\n", fname, strerror(errno));
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}
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}
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} else {
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// TODO: suggest remedies
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char *key1 = ecdsa_get_base64_public_key(ecdsa_pub);
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if(!key1) {
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fprintf(stderr, "ERROR: public Ed25519 key does not work.\n");
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return 1;
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}
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char *key2 = ecdsa_get_base64_public_key(ecdsa_priv);
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if(!key2) {
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free(key1);
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fprintf(stderr, "ERROR: private Ed25519 key does not work.\n");
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return 1;
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}
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int result = strcmp(key1, key2);
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free(key1);
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free(key2);
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if(result) {
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fprintf(stderr, "ERROR: public and private Ed25519 keys do not match.\n");
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return 1;
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}
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}
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} else {
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if(ecdsa_pub) {
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fprintf(stderr, "WARNING: A public Ed25519 key was found but no private key is known.\n");
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}
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}
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// Check whether scripts are executable
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struct dirent *ent;
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DIR *dir = opendir(confbase);
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if(!dir) {
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fprintf(stderr, "ERROR: cannot read directory %s: %s\n", confbase, strerror(errno));
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return 1;
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}
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while((ent = readdir(dir))) {
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if(strtailcmp(ent->d_name, "-up") && strtailcmp(ent->d_name, "-down")) {
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continue;
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}
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strncpy(fname, ent->d_name, sizeof(fname));
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char *dash = strrchr(fname, '-');
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if(!dash) {
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continue;
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}
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*dash = 0;
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if(strcmp(fname, "tinc") && strcmp(fname, "host") && strcmp(fname, "subnet")) {
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static bool explained = false;
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fprintf(stderr, "WARNING: Unknown script %s" SLASH "%s found.\n", confbase, ent->d_name);
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if(!explained) {
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fprintf(stderr, "The only scripts in %s executed by tinc are:\n", confbase);
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fprintf(stderr, "tinc-up, tinc-down, host-up, host-down, subnet-up and subnet-down.\n");
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explained = true;
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}
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continue;
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}
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snprintf(fname, sizeof(fname), "%s" SLASH "%s", confbase, ent->d_name);
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if(access(fname, R_OK | X_OK)) {
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if(errno != EACCES) {
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fprintf(stderr, "ERROR: cannot access %s: %s\n", fname, strerror(errno));
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continue;
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}
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fprintf(stderr, "WARNING: cannot read and execute %s: %s\n", fname, strerror(errno));
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if(ask_fix()) {
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if(chmod(fname, 0755)) {
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fprintf(stderr, "ERROR: cannot change permissions on %s: %s\n", fname, strerror(errno));
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}
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|
}
|
|
}
|
|
}
|
|
|
|
closedir(dir);
|
|
|
|
snprintf(dname, sizeof(dname), "%s" SLASH "hosts", confbase);
|
|
dir = opendir(dname);
|
|
|
|
if(!dir) {
|
|
fprintf(stderr, "ERROR: cannot read directory %s: %s\n", dname, strerror(errno));
|
|
return 1;
|
|
}
|
|
|
|
while((ent = readdir(dir))) {
|
|
if(strtailcmp(ent->d_name, "-up") && strtailcmp(ent->d_name, "-down")) {
|
|
continue;
|
|
}
|
|
|
|
strncpy(fname, ent->d_name, sizeof(fname));
|
|
char *dash = strrchr(fname, '-');
|
|
|
|
if(!dash) {
|
|
continue;
|
|
}
|
|
|
|
*dash = 0;
|
|
|
|
snprintf(fname, sizeof(fname), "%s" SLASH "hosts" SLASH "%s", confbase, ent->d_name);
|
|
|
|
if(access(fname, R_OK | X_OK)) {
|
|
if(errno != EACCES) {
|
|
fprintf(stderr, "ERROR: cannot access %s: %s\n", fname, strerror(errno));
|
|
continue;
|
|
}
|
|
|
|
fprintf(stderr, "WARNING: cannot read and execute %s: %s\n", fname, strerror(errno));
|
|
|
|
if(ask_fix()) {
|
|
if(chmod(fname, 0755)) {
|
|
fprintf(stderr, "ERROR: cannot change permissions on %s: %s\n", fname, strerror(errno));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
closedir(dir);
|
|
|
|
// Check for obsolete / unsafe / unknown configuration variables.
|
|
|
|
check_conffile(tinc_conf, true);
|
|
|
|
dir = opendir(dname);
|
|
|
|
if(dir) {
|
|
while((ent = readdir(dir))) {
|
|
if(!check_id(ent->d_name)) {
|
|
continue;
|
|
}
|
|
|
|
snprintf(fname, sizeof(fname), "%s" SLASH "hosts" SLASH "%s", confbase, ent->d_name);
|
|
check_conffile(fname, false);
|
|
}
|
|
|
|
closedir(dir);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|