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Added mremap tracing and fixed a bug in MemoryLimitListener #43

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Merged
merged 2 commits into from
Feb 10, 2024
Merged

Added mremap tracing and fixed a bug in MemoryLimitListener #43

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0f457bb
Added "Memory limit exceeded" error checking when allocatiing memory …
mikimasn Feb 6, 2024
65c5a25
Fixed a bug that caused a Memory Limit Exceeded error when trying to …
mikimasn Feb 7, 2024
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75 changes: 53 additions & 22 deletions src/limits/MemoryLimitListener.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -8,9 +8,16 @@
#include "seccomp/action/ActionTrace.h"
#include "seccomp/filter/LibSeccompFilter.h"

#include <sys/mman.h>
#include <sys/resource.h>
#include <sys/time.h>

#ifndef MREMAP_DONTUNMAP
// Due to this flag being introduced in Linux 5.7 there are many system which do
// not define it
#define MREMAP_DONTUNMAP 4
#endif

#include <csignal>
#include <cstdint>
#include <fstream>
Expand Down Expand Up @@ -40,33 +47,57 @@ MemoryLimitListener::MemoryLimitListener(uint64_t memoryLimitKb)
if (!vmPeakValid_) {
return tracer::TraceAction::CONTINUE;
}

uint64_t memoryUsage = getMemoryUsageKb() +
tracee.getSyscallArgument(1) / 1024;
memoryPeakKb_ = std::max(memoryPeakKb_, memoryUsage);
outputBuilder_->setMemoryPeak(memoryPeakKb_);
logger::debug(
"Memory usage after mmap ",
VAR(memoryUsage),
", ",
VAR(memoryPeakKb_));

if (memoryUsage > memoryLimitKb_) {
outputBuilder_->setKillReason(
printer::OutputBuilder::KillReason::MLE,
"memory limit exceeded");
logger::debug(
"Limit ",
VAR(memoryLimitKb_),
" exceeded, killing tracee");
return tracer::TraceAction::KILL;
}
return tracer::TraceAction::CONTINUE;
return handleMemoryAllocation(
tracee.getSyscallArgument(1) / 1024);
}),
Arg(0) == 0 && Arg(1) > MEMORY_LIMIT_MARGIN / 2));
}
syscallRules_.emplace_back(seccomp::SeccompRule(
"mremap",
seccomp::action::ActionTrace([this](tracer::Tracee& tracee) {
TRACE();
uint64_t old_size = tracee.getSyscallArgument(1);
uint64_t new_size = tracee.getSyscallArgument(2);
uint64_t flags = tracee.getSyscallArgument(3);
if (!vmPeakValid_) {
return tracer::TraceAction::CONTINUE;
}
bool doesntUnmap =
(flags & MREMAP_DONTUNMAP) == MREMAP_DONTUNMAP;
// Allow user to shrink its memory
if (!doesntUnmap && old_size >= new_size) {
return tracer::TraceAction::CONTINUE;
}
uint64_t newMemoryAllocated = new_size;
// Do not count already allocated memory
if (!doesntUnmap)
newMemoryAllocated -= old_size;
newMemoryAllocated /= 1024;
return handleMemoryAllocation(newMemoryAllocated);
}),
Arg(2) > MEMORY_LIMIT_MARGIN / 2));
}
tracer::TraceAction MemoryLimitListener::handleMemoryAllocation(
uint64_t allocatedMemoryKb) {
uint64_t memoryUsage = getMemoryUsageKb() + allocatedMemoryKb;
memoryPeakKb_ = std::max(memoryPeakKb_, memoryUsage);
outputBuilder_->setMemoryPeak(memoryPeakKb_);
logger::debug(
"Memory usage after allocation ",
VAR(memoryUsage),
", ",
VAR(memoryPeakKb_));

if (memoryLimitKb_ > 0 && memoryUsage > memoryLimitKb_) {
outputBuilder_->setKillReason(
printer::OutputBuilder::KillReason::MLE,
"memory limit exceeded");
logger::debug(
"Limit ", VAR(memoryLimitKb_), " exceeded, killing tracee");
return tracer::TraceAction::KILL;
}
return tracer::TraceAction::CONTINUE;
}
void MemoryLimitListener::onPostForkChild() {
TRACE();

Expand Down
1 change: 1 addition & 0 deletions src/limits/MemoryLimitListener.h
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@ class MemoryLimitListener
pid_t childPid_;

std::vector<seccomp::SeccompRule> syscallRules_;
tracer::TraceAction handleMemoryAllocation(uint64_t allocatedMemoryKb);
};

} // namespace limits
Expand Down