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platform_system_core/logd/LogAudit.cpp
Jeff Vander Stoep 54c7a5f1e7 LogAudit: remove dynamic rate limiter 
Select a low rate-limit to cut down on logspam and resulting
performance regressions.

Functionally reverts 247d682fe1
(logd: sepolicy dynamic rate limiting) and sets a static low
rate-limit. Before 247d682f, the limit was statically set to 20.
247d682f continued to support 20, but if sustained dropped the limit
to 5. This revert leaves us at 5 so as not to impact performance.

Test: /data/nativetest/logd-unit-tests/logd-unit-tests \
    --gtest_filter=logd.sepolicy_rate_limiter
    [  PASSED  ] 1 test.
Bug: 71538411
Change-Id: I6c92f4ba825cc24beb8f1f1b79258fa8097c837b
2018-01-03 12:52:58 -08:00

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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <ctype.h>
#include <endian.h>
#include <errno.h>
#include <limits.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/uio.h>
#include <syslog.h>
#include <fstream>
#include <sstream>
#include <android-base/macros.h>
#include <log/log_properties.h>
#include <private/android_filesystem_config.h>
#include <private/android_logger.h>
#include "LogAudit.h"
#include "LogBuffer.h"
#include "LogKlog.h"
#include "LogReader.h"
#include "LogUtils.h"
#include "libaudit.h"
#define KMSG_PRIORITY(PRI) \
'<', '0' + LOG_MAKEPRI(LOG_AUTH, LOG_PRI(PRI)) / 10, \
'0' + LOG_MAKEPRI(LOG_AUTH, LOG_PRI(PRI)) % 10, '>'
LogAudit::LogAudit(LogBuffer* buf, LogReader* reader, int fdDmesg)
: SocketListener(getLogSocket(), false),
logbuf(buf),
reader(reader),
fdDmesg(fdDmesg),
main(__android_logger_property_get_bool("ro.logd.auditd.main",
BOOL_DEFAULT_TRUE)),
events(__android_logger_property_get_bool("ro.logd.auditd.events",
BOOL_DEFAULT_TRUE)),
initialized(false) {
static const char auditd_message[] = { KMSG_PRIORITY(LOG_INFO),
'l',
'o',
'g',
'd',
'.',
'a',
'u',
'd',
'i',
't',
'd',
':',
' ',
's',
't',
'a',
'r',
't',
'\n' };
write(fdDmesg, auditd_message, sizeof(auditd_message));
}
bool LogAudit::onDataAvailable(SocketClient* cli) {
if (!initialized) {
prctl(PR_SET_NAME, "logd.auditd");
initialized = true;
}
struct audit_message rep;
rep.nlh.nlmsg_type = 0;
rep.nlh.nlmsg_len = 0;
rep.data[0] = '\0';
if (audit_get_reply(cli->getSocket(), &rep, GET_REPLY_BLOCKING, 0) < 0) {
SLOGE("Failed on audit_get_reply with error: %s", strerror(errno));
return false;
}
logPrint("type=%d %.*s", rep.nlh.nlmsg_type, rep.nlh.nlmsg_len, rep.data);
return true;
}
static inline bool hasMetadata(char* str, int str_len) {
// need to check and see if str already contains bug metadata from
// possibility of stuttering if log audit crashes and then reloads kernel
// messages. Kernel denials that contain metadata will either end in
// "b/[0-9]+$" or "b/[0-9]+ duplicate messages suppressed$" which will put
// a '/' character at either 9 or 39 indices away from the end of the str.
return str_len >= 39 &&
(str[str_len - 9] == '/' || str[str_len - 39] == '/');
}
std::map<std::string, std::string> LogAudit::populateDenialMap() {
std::ifstream bug_file("/system/etc/selinux/selinux_denial_metadata");
std::string line;
// allocate a map for the static map pointer in logParse to keep track of,
// this function only runs once
std::map<std::string, std::string> denial_to_bug;
if (bug_file.good()) {
std::string scontext;
std::string tcontext;
std::string tclass;
std::string bug_num;
while (std::getline(bug_file, line)) {
std::stringstream split_line(line);
split_line >> scontext >> tcontext >> tclass >> bug_num;
denial_to_bug.emplace(scontext + tcontext + tclass, bug_num);
}
}
return denial_to_bug;
}
std::string LogAudit::denialParse(const std::string& denial, char terminator,
const std::string& search_term) {
size_t start_index = denial.find(search_term);
if (start_index != std::string::npos) {
start_index += search_term.length();
return denial.substr(
start_index, denial.find(terminator, start_index) - start_index);
}
return "";
}
void LogAudit::logParse(const std::string& string, std::string* bug_num) {
if (!__android_log_is_debuggable()) {
bug_num->assign("");
return;
}
static std::map<std::string, std::string> denial_to_bug =
populateDenialMap();
std::string scontext = denialParse(string, ':', "scontext=u:object_r:");
std::string tcontext = denialParse(string, ':', "tcontext=u:object_r:");
std::string tclass = denialParse(string, ' ', "tclass=");
if (scontext.empty()) {
scontext = denialParse(string, ':', "scontext=u:r:");
}
if (tcontext.empty()) {
tcontext = denialParse(string, ':', "tcontext=u:r:");
}
auto search = denial_to_bug.find(scontext + tcontext + tclass);
if (search != denial_to_bug.end()) {
bug_num->assign(" b/" + search->second);
} else {
bug_num->assign("");
}
}
int LogAudit::logPrint(const char* fmt, ...) {
if (fmt == NULL) {
return -EINVAL;
}
va_list args;
char* str = NULL;
va_start(args, fmt);
int rc = vasprintf(&str, fmt, args);
va_end(args);
if (rc < 0) {
return rc;
}
char* cp;
// Work around kernels missing
// https://github.com/torvalds/linux/commit/b8f89caafeb55fba75b74bea25adc4e4cd91be67
// Such kernels improperly add newlines inside audit messages.
while ((cp = strchr(str, '\n'))) {
*cp = ' ';
}
while ((cp = strstr(str, " "))) {
memmove(cp, cp + 1, strlen(cp + 1) + 1);
}
bool info = strstr(str, " permissive=1") || strstr(str, " policy loaded ");
static std::string bug_metadata;
if ((fdDmesg >= 0) && initialized) {
struct iovec iov[4];
static const char log_info[] = { KMSG_PRIORITY(LOG_INFO) };
static const char log_warning[] = { KMSG_PRIORITY(LOG_WARNING) };
static const char newline[] = "\n";
// Dedupe messages, checking for identical messages starting with avc:
static unsigned count;
static char* last_str;
static bool last_info;
if (last_str != NULL) {
static const char avc[] = "): avc: ";
char* avcl = strstr(last_str, avc);
bool skip = false;
if (avcl) {
char* avcr = strstr(str, avc);
skip = avcr &&
!fastcmp<strcmp>(avcl + strlen(avc), avcr + strlen(avc));
if (skip) {
++count;
free(last_str);
last_str = strdup(str);
last_info = info;
}
}
if (!skip) {
static const char resume[] = " duplicate messages suppressed\n";
iov[0].iov_base = last_info ? const_cast<char*>(log_info)
: const_cast<char*>(log_warning);
iov[0].iov_len =
last_info ? sizeof(log_info) : sizeof(log_warning);
iov[1].iov_base = last_str;
iov[1].iov_len = strlen(last_str);
iov[2].iov_base = const_cast<char*>(bug_metadata.c_str());
iov[2].iov_len = bug_metadata.length();
if (count > 1) {
iov[3].iov_base = const_cast<char*>(resume);
iov[3].iov_len = strlen(resume);
} else {
iov[3].iov_base = const_cast<char*>(newline);
iov[3].iov_len = strlen(newline);
}
writev(fdDmesg, iov, arraysize(iov));
free(last_str);
last_str = NULL;
}
}
if (last_str == NULL) {
count = 0;
last_str = strdup(str);
last_info = info;
}
if (count == 0) {
logParse(str, &bug_metadata);
iov[0].iov_base = info ? const_cast<char*>(log_info)
: const_cast<char*>(log_warning);
iov[0].iov_len = info ? sizeof(log_info) : sizeof(log_warning);
iov[1].iov_base = str;
iov[1].iov_len = strlen(str);
iov[2].iov_base = const_cast<char*>(bug_metadata.c_str());
iov[2].iov_len = bug_metadata.length();
iov[3].iov_base = const_cast<char*>(newline);
iov[3].iov_len = strlen(newline);
writev(fdDmesg, iov, arraysize(iov));
}
}
if (!main && !events) {
free(str);
return 0;
}
pid_t pid = getpid();
pid_t tid = gettid();
uid_t uid = AID_LOGD;
log_time now;
static const char audit_str[] = " audit(";
char* timeptr = strstr(str, audit_str);
if (timeptr &&
((cp = now.strptime(timeptr + sizeof(audit_str) - 1, "%s.%q"))) &&
(*cp == ':')) {
memcpy(timeptr + sizeof(audit_str) - 1, "0.0", 3);
memmove(timeptr + sizeof(audit_str) - 1 + 3, cp, strlen(cp) + 1);
if (!isMonotonic()) {
if (android::isMonotonic(now)) {
LogKlog::convertMonotonicToReal(now);
}
} else {
if (!android::isMonotonic(now)) {
LogKlog::convertRealToMonotonic(now);
}
}
} else if (isMonotonic()) {
now = log_time(CLOCK_MONOTONIC);
} else {
now = log_time(CLOCK_REALTIME);
}
static const char pid_str[] = " pid=";
char* pidptr = strstr(str, pid_str);
if (pidptr && isdigit(pidptr[sizeof(pid_str) - 1])) {
cp = pidptr + sizeof(pid_str) - 1;
pid = 0;
while (isdigit(*cp)) {
pid = (pid * 10) + (*cp - '0');
++cp;
}
tid = pid;
logbuf->wrlock();
uid = logbuf->pidToUid(pid);
logbuf->unlock();
memmove(pidptr, cp, strlen(cp) + 1);
}
// log to events
size_t str_len = strnlen(str, LOGGER_ENTRY_MAX_PAYLOAD);
if (((fdDmesg < 0) || !initialized) && !hasMetadata(str, str_len))
logParse(str, &bug_metadata);
str_len = (str_len + bug_metadata.length() <= LOGGER_ENTRY_MAX_PAYLOAD)
? str_len + bug_metadata.length()
: LOGGER_ENTRY_MAX_PAYLOAD;
size_t message_len = str_len + sizeof(android_log_event_string_t);
log_mask_t notify = 0;
if (events) { // begin scope for event buffer
uint32_t buffer[(message_len + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
android_log_event_string_t* event =
reinterpret_cast<android_log_event_string_t*>(buffer);
event->header.tag = htole32(AUDITD_LOG_TAG);
event->type = EVENT_TYPE_STRING;
event->length = htole32(message_len);
memcpy(event->data, str, str_len - bug_metadata.length());
memcpy(event->data + str_len - bug_metadata.length(),
bug_metadata.c_str(), bug_metadata.length());
rc = logbuf->log(
LOG_ID_EVENTS, now, uid, pid, tid, reinterpret_cast<char*>(event),
(message_len <= USHRT_MAX) ? (unsigned short)message_len
: USHRT_MAX);
if (rc >= 0) {
notify |= 1 << LOG_ID_EVENTS;
}
// end scope for event buffer
}
// log to main
static const char comm_str[] = " comm=\"";
const char* comm = strstr(str, comm_str);
const char* estr = str + strlen(str);
const char* commfree = NULL;
if (comm) {
estr = comm;
comm += sizeof(comm_str) - 1;
} else if (pid == getpid()) {
pid = tid;
comm = "auditd";
} else {
logbuf->wrlock();
comm = commfree = logbuf->pidToName(pid);
logbuf->unlock();
if (!comm) {
comm = "unknown";
}
}
const char* ecomm = strchr(comm, '"');
if (ecomm) {
++ecomm;
str_len = ecomm - comm;
} else {
str_len = strlen(comm) + 1;
ecomm = "";
}
size_t prefix_len = estr - str;
if (prefix_len > LOGGER_ENTRY_MAX_PAYLOAD) {
prefix_len = LOGGER_ENTRY_MAX_PAYLOAD;
}
size_t suffix_len = strnlen(ecomm, LOGGER_ENTRY_MAX_PAYLOAD - prefix_len);
message_len = str_len + prefix_len + suffix_len + bug_metadata.length() + 2;
if (main) { // begin scope for main buffer
char newstr[message_len];
*newstr = info ? ANDROID_LOG_INFO : ANDROID_LOG_WARN;
strlcpy(newstr + 1, comm, str_len);
strncpy(newstr + 1 + str_len, str, prefix_len);
strncpy(newstr + 1 + str_len + prefix_len, ecomm, suffix_len);
strncpy(newstr + 1 + str_len + prefix_len + suffix_len,
bug_metadata.c_str(), bug_metadata.length());
rc = logbuf->log(LOG_ID_MAIN, now, uid, pid, tid, newstr,
(message_len <= USHRT_MAX) ? (unsigned short)message_len
: USHRT_MAX);
if (rc >= 0) {
notify |= 1 << LOG_ID_MAIN;
}
// end scope for main buffer
}
free(const_cast<char*>(commfree));
free(str);
if (notify) {
reader->notifyNewLog(notify);
if (rc < 0) {
rc = message_len;
}
}
return rc;
}
int LogAudit::log(char* buf, size_t len) {
char* audit = strstr(buf, " audit(");
if (!audit || (audit >= &buf[len])) {
return 0;
}
*audit = '\0';
int rc;
char* type = strstr(buf, "type=");
if (type && (type < &buf[len])) {
rc = logPrint("%s %s", type, audit + 1);
} else {
rc = logPrint("%s", audit + 1);
}
*audit = ' ';
return rc;
}
int LogAudit::getLogSocket() {
int fd = audit_open();
if (fd < 0) {
return fd;
}
if (audit_setup(fd, getpid()) < 0) {
audit_close(fd);
fd = -1;
}
return fd;
}
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