diff options
Diffstat (limited to 'daemons/ipa-slapi-plugins/ipa-otp-counter/ipa_otp_counter.c')
-rw-r--r-- | daemons/ipa-slapi-plugins/ipa-otp-counter/ipa_otp_counter.c | 454 |
1 files changed, 454 insertions, 0 deletions
diff --git a/daemons/ipa-slapi-plugins/ipa-otp-counter/ipa_otp_counter.c b/daemons/ipa-slapi-plugins/ipa-otp-counter/ipa_otp_counter.c new file mode 100644 index 000000000..24ef9e240 --- /dev/null +++ b/daemons/ipa-slapi-plugins/ipa-otp-counter/ipa_otp_counter.c @@ -0,0 +1,454 @@ +/** BEGIN COPYRIGHT BLOCK + * This program 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. + * + * This program 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/>. + * + * Additional permission under GPLv3 section 7: + * + * In the following paragraph, "GPL" means the GNU General Public + * License, version 3 or any later version, and "Non-GPL Code" means + * code that is governed neither by the GPL nor a license + * compatible with the GPL. + * + * You may link the code of this Program with Non-GPL Code and convey + * linked combinations including the two, provided that such Non-GPL + * Code only links to the code of this Program through those well + * defined interfaces identified in the file named EXCEPTION found in + * the source code files (the "Approved Interfaces"). The files of + * Non-GPL Code may instantiate templates or use macros or inline + * functions from the Approved Interfaces without causing the resulting + * work to be covered by the GPL. Only the copyright holders of this + * Program may make changes or additions to the list of Approved + * Interfaces. + * + * Authors: + * Nathaniel McCallum <npmccallum@redhat.com> + * + * Copyright (C) 2014 Red Hat, Inc. + * All rights reserved. + * END COPYRIGHT BLOCK **/ + +/** + * The purpose of this plugin is to ensure that counter/watermark values: + * 1. Have atomic operations. + * 2. Never go backwards. + * 3. Never get deleted. + */ + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif + +#include "berval.h" +#include "ldapmod.h" + +#include <limits.h> + +#include <plstr.h> + +#define COUNTER_UNSET LLONG_MIN + +static void *plugin_id; + +static long long +get_counter(Slapi_Entry *entry, const char *attr) +{ + Slapi_Attr *sattr = NULL; + + if (slapi_entry_attr_find(entry, attr, &sattr) == 0) + return slapi_entry_attr_get_longlong(entry, attr); + + return COUNTER_UNSET; +} + +/** + * Determines the name of the counter or watermark attribute based + * upon the objectClass of the entry. + * + * If no match is found, this function returns NULL indicating that + * this entry is not a known token type. + */ +static const char * +find_counter_name(Slapi_Entry *entry) +{ + static struct { + const char *clss; + const char *attr; + } table[] = { + { "ipatokenHOTP", "ipatokenHOTPcounter" }, + { "ipatokenTOTP", "ipatokenTOTPwatermark" }, + { NULL, NULL } + }; + + const char *attr = NULL; + char **clsses = NULL; + + clsses = slapi_entry_attr_get_charray(entry, "objectClass"); + if (clsses == NULL) + return NULL; + + for (size_t i = 0; attr == NULL && clsses[i] != NULL; i++) { + for (size_t j = 0; attr == NULL && table[j].clss != NULL; j++) { + if (PL_strcasecmp(table[j].clss, clsses[i]) == 0) + attr = table[j].attr; + } + } + + slapi_ch_array_free(clsses); + return attr; +} + +/** + * Normalizes the input values of counter/watermark modifications. + * + * 1. All INCREMENT and REPLACE operations need to be replace by + * equivalent DELETE/ADD combination operations. This ensures + * atomicity. + * + * 2. Any incoming DELETE operations need to be sanity checked. + * + * If no value is specified, the current counter value is added + * to the operation. Without this, we cannot guarantee that the + * operation will not causes a decrement. + * + * This function returns the size of the new LDAPMod* array or zero + * if there are no counter/watermark operations. + */ +static size_t +normalize_input(LDAPMod ***mods, const char *attr, long long ctr) +{ + LDAPMod **tmp; + size_t o; /* Counts the number of operations. */ + size_t c; /* Counts the number of counter operations. */ + size_t e; /* Counts the number of expansions. */ + + /* Get the size of the mods when all expansions are performed. */ + for (o = c = e = 0; (*mods)[o] != NULL; o++) { + if (PL_strcasecmp((*mods)[o]->mod_type, attr) != 0) + continue; + + switch ((*mods)[o]->mod_op & LDAP_MOD_OP) { + case LDAP_MOD_REPLACE: + case LDAP_MOD_INCREMENT: + e++; + default: + c++; + } + } + + if (c == 0) + return 0; + + /* Filter the modify operations. */ + tmp = (LDAPMod **) slapi_ch_calloc(o + e + 1, sizeof(LDAPMod*)); + for (size_t i = 0, j = 0; (*mods)[i] != NULL; tmp[j++] = (*mods)[i++]) { + LDAPMod *mod = (*mods)[i]; + + if (PL_strcasecmp(mod->mod_type, attr) != 0) + continue; + + /* This is not strictly needed, but simplifies the code. */ + ldapmod_convert_bvalues(mod); + + switch (mod->mod_op & LDAP_MOD_OP) { + case LDAP_MOD_DELETE: + /* Normalize input: if an empty array is allocated, free it. */ + if (mod->mod_bvalues != NULL && mod->mod_bvalues[0] == NULL) + bervals_free(&mod->mod_bvalues); + + if (mod->mod_bvalues == NULL) + mod->mod_bvalues = bervals_new_longlong(ctr); + + ctr = COUNTER_UNSET; + break; + + case LDAP_MOD_INCREMENT: + if (ctr != COUNTER_UNSET) + tmp[j++] = ldapmod_new_longlong(LDAP_MOD_DELETE, attr, ctr); + + ctr += ldapmod_get_value(mod, 1); + + bervals_free(&mod->mod_bvalues); + mod->mod_op = LDAP_MOD_ADD | LDAP_MOD_BVALUES; + mod->mod_bvalues = bervals_new_longlong(ctr); + break; + + case LDAP_MOD_REPLACE: + if (ctr != COUNTER_UNSET) + tmp[j++] = ldapmod_new_longlong(LDAP_MOD_DELETE, attr, ctr); + + mod->mod_op = LDAP_MOD_ADD | LDAP_MOD_BVALUES; + + /* Fall through. */ + + case LDAP_MOD_ADD: + ctr = ldapmod_get_value(mod, 0); + break; + } + } + + slapi_ch_free((void **) mods); + *mods = tmp; + return o + e; +} + +/** + * Simulates how the specified mods will impact the counter. + */ +static bool +simulate(LDAPMod **mods, const char *attr, long long ctr, long long *out) +{ + bool success = true; + + for (size_t i = 0; mods[i] != NULL; i++) { + if (PL_strcasecmp(mods[i]->mod_type, attr) != 0) + continue; + + switch (mods[i]->mod_op & LDAP_MOD_OP) { + case LDAP_MOD_DELETE: + if (ctr == COUNTER_UNSET) + success = false; + + ctr = COUNTER_UNSET; + break; + + case LDAP_MOD_INCREMENT: + if (ctr == COUNTER_UNSET) + success = false; + + ctr = ldapmod_get_value(mods[i], ctr + 1); + break; + + case LDAP_MOD_ADD: + if (ctr != COUNTER_UNSET) + success = false; + + /* Fall through. */ + + case LDAP_MOD_REPLACE: + ctr = ldapmod_get_value(mods[i], 0); + break; + } + } + + *out = ctr; + return success; +} + +/** + * Modifies input to ensure correct counter behavior. + * + * For non-replication operations, we change all REPLACE and INCREMENT + * operations into DELETE/ADD pair operations. We also sanity check + * incoming DELETE operations. If the request would cause the counter to + * decrement or delete, fail the operation. + * + * For replication operations, if the transaction would decrement the + * counter, delete it or modify it to the same value, we remove all mods + * related to the counter and let the replication request continue. In + * the first two cases, this enforces correct behavior. In the last case, + * this reduces write contention on the counter when a replica-set-wide + * authentication collision has occurred. + */ +static int +preop_mod(Slapi_PBlock *pb) +{ + Slapi_Entry *epre = NULL; + const char *attr = NULL; + LDAPMod **mods = NULL; + char *msg = NULL; + long long cpost; + long long cpre; + int repl = 0; + int rc = 0; + + rc |= slapi_pblock_get(pb, SLAPI_IS_REPLICATED_OPERATION, &repl); + rc |= slapi_pblock_get(pb, SLAPI_ENTRY_PRE_OP, &epre); + rc |= slapi_pblock_get(pb, SLAPI_MODIFY_MODS, &mods); + if (rc != 0 || epre == NULL || mods == NULL) + return 0; + + attr = find_counter_name(epre); + if (attr == NULL) + return 0; /* Not a token. */ + + cpre = get_counter(epre, attr); + + if (repl == 0) { + if (normalize_input(&mods, attr, cpre) != 0) + slapi_pblock_set(pb, SLAPI_MODIFY_MODS, mods); + } + + if (!simulate(mods, attr, cpre, &cpost) && repl == 0) { + msg = slapi_ch_smprintf("Invalid operation sequence on %s", attr); + goto error; + } + + if (cpost < cpre) { + if (repl == 0) { + msg = slapi_ch_smprintf("Will not %s %s", + cpost == COUNTER_UNSET ? "delete" : "decrement", attr); + goto error; + } + + /* Remove counter attribute modifications. */ + for (size_t i = 0, j = 0 ; ; i++, j++) { + mods[j] = mods[i]; + if (mods[j] == NULL) + break; + + if (PL_strcasecmp(mods[j]->mod_type, attr) == 0) + ldapmod_free(&mods[j--]); + } + } + + return 0; + +error: + rc = LDAP_UNWILLING_TO_PERFORM; + slapi_send_ldap_result(pb, rc, NULL, msg, 0, NULL); + slapi_pblock_set(pb, SLAPI_RESULT_CODE, &rc); + + slapi_ch_free_string(&msg); + return rc; +} + +static void +writeback(Slapi_Entry *entry, const char *attr, + long long cold, long long cnew) +{ + Slapi_PBlock *pb = NULL; + char dbuf[32]; + char abuf[32]; + + LDAPMod *mods[] = { + &(LDAPMod) { + LDAP_MOD_DELETE, (char *) attr, + .mod_values = (char *[]) { dbuf, NULL } + }, + &(LDAPMod) { + LDAP_MOD_ADD, (char *) attr, + .mod_values = (char *[]) { abuf, NULL } + }, + NULL + }; + + snprintf(dbuf, sizeof(dbuf), "%lld", cold); + snprintf(abuf, sizeof(abuf), "%lld", cnew); + + pb = slapi_pblock_new(); + slapi_modify_internal_set_pb(pb, slapi_entry_get_dn_const(entry), + mods, NULL, NULL, plugin_id, 0); + slapi_modify_internal_pb(pb); + slapi_pblock_destroy(pb); +} + +/** + * Ensures replications receive the highest value seen. + * + * A replication request that arrives at the server may be internally + * discarded, even if it has a higher counter value, because of a lower + * CSN. However, we always want to record the highest value seen. + * + * We solve this problem by checking the value of the replication request + * against the value of the entry after the replication. If the replication + * request contained a higher value than what the entry contains, we create + * a new modification to bump up the counter to the highest value. + * + * This check is only for replication operations. + */ +static int +postop_mod(Slapi_PBlock *pb) +{ + Slapi_Entry *epost = NULL; + Slapi_Entry *epre = NULL; + const char *attr = NULL; + LDAPMod **mods = NULL; + long long cpost; + long long cpre; + long long csim; + int repl = 0; + int rc = 0; + + rc |= slapi_pblock_get(pb, SLAPI_IS_REPLICATED_OPERATION, &repl); + rc |= slapi_pblock_get(pb, SLAPI_ENTRY_POST_OP, &epost); + rc |= slapi_pblock_get(pb, SLAPI_ENTRY_PRE_OP, &epre); + rc |= slapi_pblock_get(pb, SLAPI_MODIFY_MODS, &mods); + if (rc != 0 || epost == NULL || epre == NULL || mods == NULL) + return 0; + + if (repl == 0) + return 0; + + attr = find_counter_name(epost); + if (attr == NULL) + return 0; /* Not a token. */ + + cpost = get_counter(epost, attr); + cpre = get_counter(epre, attr); + + if (simulate(mods, attr, cpre, &csim) && csim > cpost) + writeback(epost, attr, cpost, csim); + + return 0; +} + +static int +preop_init(Slapi_PBlock *pb) +{ + return slapi_pblock_set(pb, SLAPI_PLUGIN_BE_PRE_MODIFY_FN, preop_mod); +} + +static int +postop_init(Slapi_PBlock *pb) +{ + return slapi_pblock_set(pb, SLAPI_PLUGIN_BE_POST_MODIFY_FN, postop_mod); +} + +static int +start_fn(Slapi_PBlock *pb) +{ + return 0; +} + +static int +close_fn(Slapi_PBlock *pb) +{ + return 0; +} + +int +ipa_otp_counter_init(Slapi_PBlock *pb) +{ + static const Slapi_PluginDesc desc = { + "ipa-otp-counter", + "FreeIPA", + "FreeIPA/1.0", + "Ensure proper OTP token counter operation" + }; + + int ret = 0; + + ret |= slapi_pblock_get(pb, SLAPI_PLUGIN_IDENTITY, &plugin_id); + ret |= slapi_pblock_set(pb, SLAPI_PLUGIN_VERSION, SLAPI_PLUGIN_VERSION_01); + ret |= slapi_pblock_set(pb, SLAPI_PLUGIN_DESCRIPTION, (void *) &desc); + ret |= slapi_pblock_set(pb, SLAPI_PLUGIN_START_FN, start_fn); + ret |= slapi_pblock_set(pb, SLAPI_PLUGIN_CLOSE_FN, close_fn); + ret |= slapi_register_plugin("bepreoperation", 1, __func__, preop_init, + "ipa-otp-counter bepreoperation", NULL, + plugin_id); + ret |= slapi_register_plugin("bepostoperation", 1, __func__, postop_init, + "ipa-otp-counter bepostoperation", NULL, + plugin_id); + + return ret; +} |