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Merge pull request #293 from carrerasdarren-cell/unotify-atomic-reports

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unotify: write reports privately and atomically
This commit is contained in:
Robert Swiecki
2026-08-26 20:19:16 +02:00
parent 1a13dc98fa 3ecde9562a
commit 8dd3a7343f
1 changed files with 40 additions and 2 deletions
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42
unotify/stats.cc
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@@ -1,11 +1,15 @@
#include "unotify/stats.h"
#include <errno.h>
#include <fcntl.h>
#include <google/protobuf/text_format.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <map>
#include <mutex>
#include <vector>
#include "logs.h"
#include "util.h"
@@ -17,6 +21,41 @@ static std::mutex stats_mu;
* Uses std::map which requires SyscallRecord to have operator<. */
static std::map<SyscallRecord, size_t> stats;
/* Reports can contain traced argv and environment data. Write privately and replace the
* destination instead of following it. */
static bool writeReportAtomically(const std::string& path, const std::string& report) {
std::string tmp_template = path + ".tmp.XXXXXX";
std::vector<char> tmp_path(tmp_template.begin(), tmp_template.end());
tmp_path.push_back('\0');
int fd = mkostemp(tmp_path.data(), O_CLOEXEC);
if (fd == -1) {
return false;
}
if (!util::writeToFd(fd, report.data(), report.size())) {
int saved_errno = errno != 0 ? errno : EIO;
close(fd);
unlink(tmp_path.data());
errno = saved_errno;
return false;
}
if (close(fd) == -1) {
int saved_errno = errno;
unlink(tmp_path.data());
errno = saved_errno;
return false;
}
if (rename(tmp_path.data(), path.c_str()) == -1) {
int saved_errno = errno;
unlink(tmp_path.data());
errno = saved_errno;
return false;
}
return true;
}
void addStat(const SyscallRecord& rec) {
std::lock_guard<std::mutex> lock(stats_mu);
stats[rec]++;
@@ -178,8 +217,7 @@ void printStats(nsj_t* nsj) {
LOG_I("unotify report:\n%s", text_report.c_str());
if (!nsj->njc.seccomp_unotify_report().empty()) {
if (!util::writeBufToFile(nsj->njc.seccomp_unotify_report().c_str(),
text_report.data(), text_report.size(), O_CREAT | O_WRONLY | O_TRUNC)) {
if (!writeReportAtomically(nsj->njc.seccomp_unotify_report(), text_report)) {
PLOG_W("Failed to write unotify report to %s",
nsj->njc.seccomp_unotify_report().c_str());
}