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/**
* Copyright (C) 2023-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include <elf.h>
#include <link.h>
#include <sys/mman.h>
#include <vector>
#include "mongo/db/initialize_server_global_state.h"
#include "mongo/db/initialize_server_global_state_gen.h"
#include "mongo/logv2/log.h"
#include "mongo/util/hex.h"
#include "mongo/util/pin_code_segments_params_gen.h"
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kControl
namespace mongo {
namespace {
using ElfWEhdr = ElfW(Ehdr);
using ElfWHalf = ElfW(Half);
using ElfWPhdr = ElfW(Phdr);
struct CodeSegment {
void* addr;
size_t memSize;
};
int appendCodeSegments(dl_phdr_info* info, size_t size, void* data) {
auto segments = reinterpret_cast<std::vector<CodeSegment>*>(data);
for (ElfWHalf i = 0; i < info->dlpi_phnum; ++i) {
const ElfWPhdr& phdr(info->dlpi_phdr[i]);
if (phdr.p_type != PT_LOAD) {
// Code segments must be of LOAD type.
continue;
}
if (auto f = phdr.p_flags; f & PF_R && f & PF_X && !(f & PF_W)) {
// Code segments typically have read and execute permissions, but not writable
// permissions. Meanwhile, data segments, which we want to ignore, typically have
// read, write and execute permissions.
continue;
}
segments->push_back(
{reinterpret_cast<void*>(info->dlpi_addr + phdr.p_vaddr), phdr.p_memsz});
}
return 0;
}
std::vector<CodeSegment> getCodeSegments() {
std::vector<CodeSegment> segments;
dl_iterate_phdr(appendCodeSegments, &segments);
return segments;
}
MONGO_INITIALIZER(PinCodeSegments)(InitializerContext*) {
if (!gLockCodeSegmentsInMemory) {
return;
}
LOGV2(7394303, "Pinning code segments");
size_t lockedMemSize = 0;
auto codeSegments = getCodeSegments();
for (auto&& segment : codeSegments) {
if (mlock(segment.addr, segment.memSize) != 0) {
auto ec = lastSystemError();
LOGV2_FATAL(
7394301,
"Failed to lock code segment, ensure system ulimits are properly configured",
"error"_attr = errorMessage(ec),
"address"_attr = unsignedHex(reinterpret_cast<uintptr_t>(segment.addr)),
"memSize"_attr = segment.memSize);
}
lockedMemSize += segment.memSize;
}
LOGV2(7394302,
"Successfully locked code segments into memory",
"numSegments"_attr = codeSegments.size(),
"totalLockedMemSize"_attr = lockedMemSize);
}
} // namespace
} // namespace mongo
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