/* * Copyright (C) 2007 Red Hat, Inc. * * This library 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 library 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 library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * Authors: * Mark McLoughlin */ #include #include "iptables.h" #include #include #include #include #include #include #include #include #include #include #include #include #include "internal.h" #define qemudLog(level, msg...) fprintf(stderr, msg) enum { ADD = 0, REMOVE }; enum { WITH_ERRORS = 0, NO_ERRORS }; typedef struct { char *rule; char **argv; int flipflop; } iptRule; typedef struct { char *table; char *chain; int nrules; iptRule *rules; #ifdef IPTABLES_DIR char dir[PATH_MAX]; char path[PATH_MAX]; #endif /* IPTABLES_DIR */ } iptRules; struct _iptablesContext { iptRules *input_filter; iptRules *forward_filter; iptRules *nat_postrouting; }; #ifdef IPTABLES_DIR static int writeRules(const char *path, const iptRules *rules, int nrules) { char tmp[PATH_MAX]; FILE *f; int istmp; int i; if (nrules == 0 && unlink(path) == 0) return 0; if (snprintf(tmp, PATH_MAX, "%s.new", path) >= PATH_MAX) return EINVAL; istmp = 1; if (!(f = fopen(tmp, "w"))) { istmp = 0; if (!(f = fopen(path, "w"))) return errno; } for (i = 0; i < nrules; i++) { if (fputs(rules[i].rule, f) == EOF || fputc('\n', f) == EOF) { fclose(f); if (istmp) unlink(tmp); return errno; } } fclose(f); if (istmp && rename(tmp, path) < 0) { unlink(tmp); return errno; } if (istmp) unlink(tmp); return 0; } static int ensureDir(const char *path) { struct stat st; char parent[PATH_MAX]; char *p; int err; if (stat(path, &st) >= 0) return 0; strncpy(parent, path, PATH_MAX); parent[PATH_MAX - 1] = '\0'; if (!(p = strrchr(parent, '/'))) return EINVAL; if (p == parent) return EPERM; *p = '\0'; if ((err = ensureDir(parent))) return err; if (mkdir(path, 0700) < 0 && errno != EEXIST) return errno; return 0; } static int buildDir(const char *table, char *path, int maxlen) { if (snprintf(path, maxlen, IPTABLES_DIR "/%s", table) >= maxlen) return EINVAL; else return 0; } static int buildPath(const char *table, const char *chain, char *path, int maxlen) { if (snprintf(path, maxlen, IPTABLES_DIR "/%s/%s.chain", table, chain) >= maxlen) return EINVAL; else return 0; } #endif /* IPTABLES_DIR */ static void iptRuleFree(iptRule *rule) { if (rule->rule) free(rule->rule); rule->rule = NULL; if (rule->argv) { int i = 0; while (rule->argv[i]) free(rule->argv[i++]); free(rule->argv); rule->argv = NULL; } } static int iptRulesAppend(iptRules *rules, char *rule, char **argv, int flipflop) { iptRule *r; if (!(r = (iptRule *)realloc(rules->rules, sizeof(iptRule) * (rules->nrules+1)))) { int i = 0; while (argv[i]) free(argv[i++]); free(argv); return ENOMEM; } rules->rules = r; rules->rules[rules->nrules].rule = rule; rules->rules[rules->nrules].argv = argv; rules->rules[rules->nrules].flipflop = flipflop; rules->nrules++; #ifdef IPTABLES_DIR { int err; if ((err = ensureDir(rules->dir))) return err; if ((err = writeRules(rules->path, rules->rules, rules->nrules))) return err; } #endif /* IPTABLES_DIR */ return 0; } static int iptRulesRemove(iptRules *rules, char *rule) { int i; for (i = 0; i < rules->nrules; i++) if (!strcmp(rules->rules[i].rule, rule)) break; if (i >= rules->nrules) return EINVAL; iptRuleFree(&rules->rules[i]); memmove(&rules->rules[i], &rules->rules[i+1], (rules->nrules - i - 1) * sizeof (iptRule)); rules->nrules--; #ifdef IPTABLES_DIR { int err; if ((err = writeRules(rules->path, rules->rules, rules->nrules))) return err; } #endif /* IPTABLES_DIR */ return 0; } static void iptRulesFree(iptRules *rules) { int i; if (rules->table) { free(rules->table); rules->table = NULL; } if (rules->chain) { free(rules->chain); rules->chain = NULL; } if (rules->rules) { for (i = 0; i < rules->nrules; i++) iptRuleFree(&rules->rules[i]); free(rules->rules); rules->rules = NULL; rules->nrules = 0; } #ifdef IPTABLES_DIR rules->dir[0] = '\0'; rules->path[0] = '\0'; #endif /* IPTABLES_DIR */ free(rules); } static iptRules * iptRulesNew(const char *table, const char *chain) { iptRules *rules; if (!(rules = (iptRules *)calloc(1, sizeof (iptRules)))) return NULL; if (!(rules->table = strdup(table))) goto error; if (!(rules->chain = strdup(chain))) goto error; rules->rules = NULL; rules->nrules = 0; #ifdef IPTABLES_DIR if (buildDir(table, rules->dir, sizeof(rules->dir))) goto error; if (buildPath(table, chain, rules->path, sizeof(rules->path))) goto error; #endif /* IPTABLES_DIR */ return rules; error: iptRulesFree(rules); return NULL; } static int iptablesSpawn(int errors, char * const *argv) { pid_t pid, ret; int status; int null = -1; if (errors == NO_ERRORS && (null = open(_PATH_DEVNULL, O_RDONLY)) < 0) return errno; pid = fork(); if (pid == -1) { if (errors == NO_ERRORS) close(null); return errno; } if (pid == 0) { /* child */ if (errors == NO_ERRORS) { dup2(null, STDIN_FILENO); dup2(null, STDOUT_FILENO); dup2(null, STDERR_FILENO); close(null); } execvp(argv[0], argv); _exit (1); } if (errors == NO_ERRORS) close(null); while ((ret = waitpid(pid, &status, 0) == -1) && errno == EINTR); if (ret == -1) return errno; if (errors == NO_ERRORS) return 0; else return (WIFEXITED(status) && WEXITSTATUS(status) == 0) ? 0 : EINVAL; } static int iptablesAddRemoveChain(iptRules *rules, int action) { char **argv; int retval = ENOMEM; int n; n = 1 + /* /sbin/iptables */ 2 + /* --table foo */ 2; /* --new-chain bar */ if (!(argv = (char **)calloc(n + 1, sizeof(char *)))) goto error; n = 0; if (!(argv[n++] = strdup(IPTABLES_PATH))) goto error; if (!(argv[n++] = strdup("--table"))) goto error; if (!(argv[n++] = strdup(rules->table))) goto error; if (!(argv[n++] = strdup(action == ADD ? "--new-chain" : "--delete-chain"))) goto error; if (!(argv[n++] = strdup(rules->chain))) goto error; retval = iptablesSpawn(NO_ERRORS, argv); error: if (argv) { n = 0; while (argv[n]) free(argv[n++]); free(argv); } return retval; } static int iptablesAddRemoveRule(iptRules *rules, int action, const char *arg, ...) { va_list args; int retval = ENOMEM; char **argv; char *rule = NULL, *p; const char *s; int n, rulelen, flipflop; n = 1 + /* /sbin/iptables */ 2 + /* --table foo */ 2 + /* --insert bar */ 1; /* arg */ rulelen = strlen(arg) + 1; va_start(args, arg); while ((s = va_arg(args, const char *))) { n++; rulelen += strlen(s) + 1; } va_end(args); if (!(argv = (char **)calloc(n + 1, sizeof(char *)))) goto error; if (!(rule = (char *)malloc(rulelen))) goto error; n = 0; if (!(argv[n++] = strdup(IPTABLES_PATH))) goto error; if (!(argv[n++] = strdup("--table"))) goto error; if (!(argv[n++] = strdup(rules->table))) goto error; flipflop = n; if (!(argv[n++] = strdup(action == ADD ? "--insert" : "--delete"))) goto error; if (!(argv[n++] = strdup(rules->chain))) goto error; if (!(argv[n++] = strdup(arg))) goto error; p = strcpy(rule, arg); p += strlen(arg); va_start(args, arg); while ((s = va_arg(args, const char *))) { if (!(argv[n++] = strdup(s))) goto error; *(p++) = ' '; strcpy(p, s); p += strlen(s); } va_end(args); *p = '\0'; if (action == ADD && (retval = iptablesAddRemoveChain(rules, action))) goto error; if ((retval = iptablesSpawn(WITH_ERRORS, argv))) goto error; if (action == REMOVE && (retval = iptablesAddRemoveChain(rules, action))) goto error; if (action == ADD) { retval = iptRulesAppend(rules, rule, argv, flipflop); rule = NULL; argv = NULL; } else { retval = iptRulesRemove(rules, rule); } error: if (rule) free(rule); if (argv) { n = 0; while (argv[n]) free(argv[n++]); free(argv); } return retval; } /** * iptablesContextNew: * * Create a new IPtable context * * Returns a pointer to the new structure or NULL in case of error */ iptablesContext * iptablesContextNew(void) { iptablesContext *ctx; if (!(ctx = (iptablesContext *) calloc(1, sizeof (iptablesContext)))) return NULL; if (!(ctx->input_filter = iptRulesNew("filter", IPTABLES_PREFIX "INPUT"))) goto error; if (!(ctx->forward_filter = iptRulesNew("filter", IPTABLES_PREFIX "FORWARD"))) goto error; if (!(ctx->nat_postrouting = iptRulesNew("nat", IPTABLES_PREFIX "POSTROUTING"))) goto error; return ctx; error: iptablesContextFree(ctx); return NULL; } /** * iptablesContextFree: * @ctx: pointer to the IP table context * * Free the ressources associated with an IP table context */ void iptablesContextFree(iptablesContext *ctx) { if (ctx->input_filter) iptRulesFree(ctx->input_filter); if (ctx->forward_filter) iptRulesFree(ctx->forward_filter); if (ctx->nat_postrouting) iptRulesFree(ctx->nat_postrouting); free(ctx); } static void iptRulesReload(iptRules *rules) { int i; int retval; for (i = 0; i < rules->nrules; i++) { iptRule *rule = &rules->rules[i]; char *orig; orig = rule->argv[rule->flipflop]; rule->argv[rule->flipflop] = (char *) "--delete"; if ((retval = iptablesSpawn(WITH_ERRORS, rule->argv))) qemudLog(QEMUD_WARN, "Failed to remove iptables rule '%s' from chain '%s' in table '%s': %s", rule->rule, rules->chain, rules->table, strerror(errno)); rule->argv[rule->flipflop] = orig; } if ((retval = iptablesAddRemoveChain(rules, REMOVE)) || (retval = iptablesAddRemoveChain(rules, ADD))) qemudLog(QEMUD_WARN, "Failed to re-create chain '%s' in table '%s': %s", rules->chain, rules->table, strerror(retval)); for (i = 0; i < rules->nrules; i++) if ((retval = iptablesSpawn(WITH_ERRORS, rules->rules[i].argv))) qemudLog(QEMUD_WARN, "Failed to add iptables rule '%s' to chain '%s' in table '%s': %s", rules->rules[i].rule, rules->chain, rules->table, strerror(retval)); } /** * iptablesReloadRules: * @ctx: pointer to the IP table context * * Reloads all the IP table rules associated to a context */ void iptablesReloadRules(iptablesContext *ctx) { iptRulesReload(ctx->input_filter); iptRulesReload(ctx->forward_filter); iptRulesReload(ctx->nat_postrouting); } static int iptablesInput(iptablesContext *ctx, const char *iface, int port, int action, int tcp) { char portstr[32]; snprintf(portstr, sizeof(portstr), "%d", port); portstr[sizeof(portstr) - 1] = '\0'; return iptablesAddRemoveRule(ctx->input_filter, action, "--in-interface", iface, "--protocol", tcp ? "tcp" : "udp", "--destination-port", portstr, "--jump", "ACCEPT", NULL); } /** * iptablesAddTcpInput: * @ctx: pointer to the IP table context * @iface: the interface name * @port: the TCP port to add * * Add an input to the IP table allowing access to the given @port on * the given @iface interface for TCP packets * * Returns 0 in case of success or an error code in case of error */ int iptablesAddTcpInput(iptablesContext *ctx, const char *iface, int port) { return iptablesInput(ctx, iface, port, ADD, 1); } /** * iptablesRemoveTcpInput: * @ctx: pointer to the IP table context * @iface: the interface name * @port: the TCP port to remove * * Removes an input from the IP table, hence forbiding access to the given * @port on the given @iface interface for TCP packets * * Returns 0 in case of success or an error code in case of error */ int iptablesRemoveTcpInput(iptablesContext *ctx, const char *iface, int port) { return iptablesInput(ctx, iface, port, REMOVE, 1); } /** * iptablesAddUdpInput: * @ctx: pointer to the IP table context * @iface: the interface name * @port: the UDP port to add * * Add an input to the IP table allowing access to the given @port on * the given @iface interface for UDP packets * * Returns 0 in case of success or an error code in case of error */ int iptablesAddUdpInput(iptablesContext *ctx, const char *iface, int port) { return iptablesInput(ctx, iface, port, ADD, 0); } /** * iptablesRemoveUdpInput: * @ctx: pointer to the IP table context * @iface: the interface name * @port: the UDP port to remove * * Removes an input from the IP table, hence forbiding access to the given * @port on the given @iface interface for UDP packets * * Returns 0 in case of success or an error code in case of error */ int iptablesRemoveUdpInput(iptablesContext *ctx, const char *iface, int port) { return iptablesInput(ctx, iface, port, REMOVE, 0); } /* Allow all traffic coming from the bridge, with a valid network address * to proceed to WAN */ static int iptablesForwardAllowOut(iptablesContext *ctx, const char *network, const char *iface, const char *physdev, int action) { if (physdev && physdev[0]) { return iptablesAddRemoveRule(ctx->forward_filter, action, "--source", network, "--in-interface", iface, "--out-interface", physdev, "--jump", "ACCEPT", NULL); } else { return iptablesAddRemoveRule(ctx->forward_filter, action, "--source", network, "--in-interface", iface, "--jump", "ACCEPT", NULL); } } /** * iptablesAddForwardAllowOut: * @ctx: pointer to the IP table context * @network: the source network name * @iface: the source interface name * @physdev: the physical output device * * Add a rule to the IP table context to allow the traffic for the * network @network via interface @iface to be forwarded to * @physdev device. This allow the outbound traffic on a bridge. * * Returns 0 in case of success or an error code otherwise */ int iptablesAddForwardAllowOut(iptablesContext *ctx, const char *network, const char *iface, const char *physdev) { return iptablesForwardAllowOut(ctx, network, iface, physdev, ADD); } /** * iptablesRemoveForwardAllowOut: * @ctx: pointer to the IP table context * @network: the source network name * @iface: the source interface name * @physdev: the physical output device * * Remove a rule from the IP table context hence forbidding forwarding * of the traffic for the network @network via interface @iface * to the @physdev device output. This stops the outbound traffic on a bridge. * * Returns 0 in case of success or an error code otherwise */ int iptablesRemoveForwardAllowOut(iptablesContext *ctx, const char *network, const char *iface, const char *physdev) { return iptablesForwardAllowOut(ctx, network, iface, physdev, REMOVE); } /* Allow all traffic destined to the bridge, with a valid network address * and associated with an existing connection */ static int iptablesForwardAllowIn(iptablesContext *ctx, const char *network, const char *iface, const char *physdev, int action) { if (physdev && physdev[0]) { return iptablesAddRemoveRule(ctx->forward_filter, action, "--destination", network, "--in-interface", physdev, "--out-interface", iface, "--match", "state", "--state", "ESTABLISHED,RELATED", "--jump", "ACCEPT", NULL); } else { return iptablesAddRemoveRule(ctx->forward_filter, action, "--destination", network, "--out-interface", iface, "--match", "state", "--state", "ESTABLISHED,RELATED", "--jump", "ACCEPT", NULL); } } /** * iptablesAddForwardAllowIn: * @ctx: pointer to the IP table context * @network: the source network name * @iface: the output interface name * @physdev: the physical input device or NULL * * Add rules to the IP table context to allow the traffic for the * network @network on @physdev device to be forwarded to * interface @iface. This allow the inbound traffic on a bridge. * * Returns 0 in case of success or an error code otherwise */ int iptablesAddForwardAllowIn(iptablesContext *ctx, const char *network, const char *iface, const char *physdev) { return iptablesForwardAllowIn(ctx, network, iface, physdev, ADD); } /** * iptablesRemoveForwardAllowIn: * @ctx: pointer to the IP table context * @network: the source network name * @iface: the output interface name * @physdev: the physical input device or NULL * * Remove rules from the IP table context hence forbidding the traffic for * network @network on @physdev device to be forwarded to * interface @iface. This stops the inbound traffic on a bridge. * * Returns 0 in case of success or an error code otherwise */ int iptablesRemoveForwardAllowIn(iptablesContext *ctx, const char *network, const char *iface, const char *physdev) { return iptablesForwardAllowIn(ctx, network, iface, physdev, REMOVE); } /* Allow all traffic between guests on the same bridge, * with a valid network address */ static int iptablesForwardAllowCross(iptablesContext *ctx, const char *iface, int action) { return iptablesAddRemoveRule(ctx->forward_filter, action, "--in-interface", iface, "--out-interface", iface, "--jump", "ACCEPT", NULL); } /** * iptablesAddForwardAllowCross: * @ctx: pointer to the IP table context * @iface: the input/output interface name * * Add rules to the IP table context to allow traffic to cross that * interface. It allows all traffic between guests on the same bridge * represented by that interface. * * Returns 0 in case of success or an error code otherwise */ int iptablesAddForwardAllowCross(iptablesContext *ctx, const char *iface) { return iptablesForwardAllowCross(ctx, iface, ADD); } /** * iptablesRemoveForwardAllowCross: * @ctx: pointer to the IP table context * @iface: the input/output interface name * * Remove rules to the IP table context to block traffic to cross that * interface. It forbids traffic between guests on the same bridge * represented by that interface. * * Returns 0 in case of success or an error code otherwise */ int iptablesRemoveForwardAllowCross(iptablesContext *ctx, const char *iface) { return iptablesForwardAllowCross(ctx, iface, REMOVE); } /* Drop all traffic trying to forward from the bridge. * ie the bridge is the in interface */ static int iptablesForwardRejectOut(iptablesContext *ctx, const char *iface, int action) { return iptablesAddRemoveRule(ctx->forward_filter, action, "--in-interface", iface, "--jump", "REJECT", NULL); } /** * iptablesAddForwardRejectOut: * @ctx: pointer to the IP table context * @iface: the output interface name * * Add rules to the IP table context to forbid all traffic to that * interface. It forbids forwarding from the bridge to that interface. * * Returns 0 in case of success or an error code otherwise */ int iptablesAddForwardRejectOut(iptablesContext *ctx, const char *iface) { return iptablesForwardRejectOut(ctx, iface, ADD); } /** * iptablesRemoveForwardRejectOut: * @ctx: pointer to the IP table context * @iface: the output interface name * * Remove rules from the IP table context forbidding all traffic to that * interface. It reallow forwarding from the bridge to that interface. * * Returns 0 in case of success or an error code otherwise */ int iptablesRemoveForwardRejectOut(iptablesContext *ctx, const char *iface) { return iptablesForwardRejectOut(ctx, iface, REMOVE); } /* Drop all traffic trying to forward to the bridge. * ie the bridge is the out interface */ static int iptablesForwardRejectIn(iptablesContext *ctx, const char *iface, int action) { return iptablesAddRemoveRule(ctx->forward_filter, action, "--out-interface", iface, "--jump", "REJECT", NULL); } /** * iptablesAddForwardRejectIn: * @ctx: pointer to the IP table context * @iface: the input interface name * * Add rules to the IP table context to forbid all traffic from that * interface. It forbids forwarding from that interface to the bridge. * * Returns 0 in case of success or an error code otherwise */ int iptablesAddForwardRejectIn(iptablesContext *ctx, const char *iface) { return iptablesForwardRejectIn(ctx, iface, ADD); } /** * iptablesRemoveForwardRejectIn: * @ctx: pointer to the IP table context * @iface: the input interface name * * Remove rules from the IP table context forbidding all traffic from that * interface. It allows forwarding from that interface to the bridge. * * Returns 0 in case of success or an error code otherwise */ int iptablesRemoveForwardRejectIn(iptablesContext *ctx, const char *iface) { return iptablesForwardRejectIn(ctx, iface, REMOVE); } /* Masquerade all traffic coming from the network associated * with the bridge */ static int iptablesForwardMasquerade(iptablesContext *ctx, const char *network, const char *physdev, int action) { if (physdev && physdev[0]) { return iptablesAddRemoveRule(ctx->nat_postrouting, action, "--source", network, "--out-interface", physdev, "--jump", "MASQUERADE", NULL); } else { return iptablesAddRemoveRule(ctx->nat_postrouting, action, "--source", network, "--jump", "MASQUERADE", NULL); } } /** * iptablesAddForwardMasquerade: * @ctx: pointer to the IP table context * @network: the source network name * @physdev: the physical input device or NULL * * Add rules to the IP table context to allow masquerading * network @network on @physdev. This allow the bridge to * masquerade for that network (on @physdev). * * Returns 0 in case of success or an error code otherwise */ int iptablesAddForwardMasquerade(iptablesContext *ctx, const char *network, const char *physdev) { return iptablesForwardMasquerade(ctx, network, physdev, ADD); } /** * iptablesRemoveForwardMasquerade: * @ctx: pointer to the IP table context * @network: the source network name * @physdev: the physical input device or NULL * * Remove rules from the IP table context to stop masquerading * network @network on @physdev. This stops the bridge from * masquerading for that network (on @physdev). * * Returns 0 in case of success or an error code otherwise */ int iptablesRemoveForwardMasquerade(iptablesContext *ctx, const char *network, const char *physdev) { return iptablesForwardMasquerade(ctx, network, physdev, REMOVE); } /* * Local variables: * indent-tabs-mode: nil * c-indent-level: 4 * c-basic-offset: 4 * tab-width: 4 * End: */