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Merge pull request #2688 from ziollek/lmdb_single_env

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LMDB - fix integration, restoring ability of use lmdb with nginx-modsecurity
This commit is contained in:
martinhsv 2022-04-29 13:08:39 -04:00 committed by GitHub
commit 83c302e6ab
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2 changed files with 88 additions and 23 deletions
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65
src/collection/backend/lmdb.cc
View File

@ -22,6 +22,8 @@
#include <string>
#include <memory>
#include <pthread.h>
#include "modsecurity/variable_value.h"
#include "src/utils/regex.h"
#include "src/variables/variable.h"
@ -36,22 +38,17 @@ namespace backend {
#ifdef WITH_LMDB
LMDB::LMDB(std::string name) :
Collection(name), m_env(NULL) {
MDB_txn *txn;
mdb_env_create(&m_env);
mdb_env_open(m_env, "./modsec-shared-collections",
MDB_WRITEMAP | MDB_NOSUBDIR, 0664);
mdb_txn_begin(m_env, NULL, 0, &txn);
mdb_dbi_open(txn, NULL, MDB_CREATE | MDB_DUPSORT, &m_dbi);
mdb_txn_commit(txn);
Collection(name), m_env(NULL), isOpen(false) {}
int LMDB::txn_begin(unsigned int flags, MDB_txn **ret) {
if (!isOpen) {
m_env = MDBEnvProvider::GetInstance().GetEnv();
m_dbi = *(MDBEnvProvider::GetInstance().GetDBI());
isOpen = true;
}
return mdb_txn_begin(m_env, NULL, flags, ret);
}
LMDB::~LMDB() {
mdb_env_close(m_env);
}
void LMDB::string2val(const std::string& str, MDB_val *val) {
val->mv_size = sizeof(char)*(str.size());
val->mv_data = const_cast<char *>(str.c_str());
@ -159,7 +156,7 @@ std::unique_ptr<std::string> LMDB::resolveFirst(const std::string& var) {
string2val(var, &mdb_key);
rc = mdb_txn_begin(m_env, NULL, MDB_RDONLY, &txn);
rc = txn_begin(MDB_RDONLY, &txn);
lmdb_debug(rc, "txn", "resolveFirst");
if (rc != 0) {
goto end_txn;
@ -192,7 +189,7 @@ bool LMDB::storeOrUpdateFirst(const std::string &key,
string2val(key, &mdb_key);
string2val(value, &mdb_value);
rc = mdb_txn_begin(m_env, NULL, 0, &txn);
rc = txn_begin(0, &txn);
lmdb_debug(rc, "txn", "storeOrUpdateFirst");
if (rc != 0) {
goto end_txn;
@ -240,7 +237,7 @@ void LMDB::resolveSingleMatch(const std::string& var,
MDB_val mdb_value_ret;
MDB_cursor *cursor;
rc = mdb_txn_begin(m_env, NULL, MDB_RDONLY, &txn);
rc = txn_begin(MDB_RDONLY, &txn);
lmdb_debug(rc, "txn", "resolveSingleMatch");
if (rc != 0) {
goto end_txn;
@ -271,7 +268,7 @@ void LMDB::store(std::string key, std::string value) {
int rc;
MDB_stat mst;
rc = mdb_txn_begin(m_env, NULL, 0, &txn);
rc = txn_begin(0, &txn);
lmdb_debug(rc, "txn", "store");
if (rc != 0) {
goto end_txn;
@ -310,7 +307,7 @@ bool LMDB::updateFirst(const std::string &key,
MDB_val mdb_value;
MDB_val mdb_value_ret;
rc = mdb_txn_begin(m_env, NULL, 0, &txn);
rc = txn_begin(0, &txn);
lmdb_debug(rc, "txn", "updateFirst");
if (rc != 0) {
goto end_txn;
@ -364,7 +361,7 @@ void LMDB::del(const std::string& key) {
MDB_val mdb_value_ret;
MDB_stat mst;
rc = mdb_txn_begin(m_env, NULL, 0, &txn);
rc = txn_begin(0, &txn);
lmdb_debug(rc, "txn", "del");
if (rc != 0) {
goto end_txn;
@ -411,7 +408,7 @@ void LMDB::resolveMultiMatches(const std::string& var,
size_t keySize = var.size();
MDB_cursor *cursor;
rc = mdb_txn_begin(m_env, NULL, MDB_RDONLY, &txn);
rc = txn_begin(MDB_RDONLY, &txn);
lmdb_debug(rc, "txn", "resolveMultiMatches");
if (rc != 0) {
goto end_txn;
@ -465,7 +462,7 @@ void LMDB::resolveRegularExpression(const std::string& var,
Utils::Regex r(var, true);
rc = mdb_txn_begin(m_env, NULL, MDB_RDONLY, &txn);
rc = txn_begin(MDB_RDONLY, &txn);
lmdb_debug(rc, "txn", "resolveRegularExpression");
if (rc != 0) {
goto end_txn;
@ -503,6 +500,30 @@ end_txn:
return;
}
MDBEnvProvider::MDBEnvProvider() : m_env(NULL) {
MDB_txn *txn;
mdb_env_create(&m_env);
mdb_env_open(m_env, "./modsec-shared-collections",
MDB_WRITEMAP | MDB_NOSUBDIR, 0664);
mdb_txn_begin(m_env, NULL, 0, &txn);
mdb_dbi_open(txn, NULL, MDB_CREATE | MDB_DUPSORT, &m_dbi);
mdb_txn_commit(txn);
}
MDB_env* MDBEnvProvider::GetEnv() {
return m_env;
}
MDB_dbi* MDBEnvProvider::GetDBI() {
return &m_dbi;
}
MDBEnvProvider::~MDBEnvProvider() {
mdb_dbi_close(m_env, m_dbi);
mdb_env_close(m_env);
}
#endif
} // namespace backend

46
src/collection/backend/lmdb.h
View File

@ -48,11 +48,53 @@ namespace modsecurity {
namespace collection {
namespace backend {
/**
* The MDBEnvProvider class defines the `GetInstance` method that serves as an
* alternative to constructor and lets clients access the same instance of this
* class over and over. Its used to provide single MDB_env instance for each collection
* that uses lmdb to store and retrieve data. That approach satisfies lmdb requirement:
*
* "LMDB uses POSIX locks on files, and these locks have issues if one process opens
* a file multiple times. Because of this, do not mdb_env_open() a file multiple
* times from a single process."
*
* Creation of MDB_env is delayed to moment when first transaction is opened.
* This approach prevents passing env object to forked processes.
* In that way next lmdb requirement be satisfied:
*
* "Use an MDB_env* in the process which opened it, without fork()ing."
*/
class MDBEnvProvider {
public:
MDBEnvProvider(MDBEnvProvider &other) = delete;
void operator=(const MDBEnvProvider &) = delete;
/**
* This is the static method that controls the access to the singleton
* instance. On the first run, it creates a singleton object and places it
* into the static field. On subsequent runs, it returns the client existing
* object stored in the static field (Meyers Singleton implementation).
*/
static MDBEnvProvider& GetInstance() {
static MDBEnvProvider instance;
return instance;
}
MDB_env* GetEnv();
MDB_dbi* GetDBI();
~MDBEnvProvider();
private:
MDB_env *m_env;
MDB_dbi m_dbi;
MDBEnvProvider();
};
class LMDB :
public Collection {
public:
explicit LMDB(std::string name);
~LMDB();
void store(std::string key, std::string value) override;
bool storeOrUpdateFirst(const std::string &key,
@ -75,11 +117,13 @@ class LMDB :
variables::KeyExclusions &ke) override;
private:
int txn_begin(unsigned int flags, MDB_txn **ret);
void string2val(const std::string& str, MDB_val *val);
void inline lmdb_debug(int rc, std::string op, std::string scope);
MDB_env *m_env;
MDB_dbi m_dbi;
bool isOpen;
};
} // namespace backend