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platform_system_core/logd/LogBuffer.cpp
Tom Cherry 64458c79cd logd: always report the UID of a log message 
logd currently only reports the UID of a log message for 'privileged'
readers (those with a uid or gid of root, system, or log).  However,
UIDs are not particularly sensitive.  Much more importantly,
non-privileged readers can only see less messages from their own UID,
so this restriction is essentially a no-op, as those readers will
already know their own uid.

Test: liblog and logd unit tests
Change-Id: I9da7d15eb840ba3200128391e70d618eec79f988
2019-10-16 13:59:26 +00:00

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/*
* Copyright (C) 2012-2014 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.
*/
// for manual checking of stale entries during LogBuffer::erase()
//#define DEBUG_CHECK_FOR_STALE_ENTRIES
#include <ctype.h>
#include <endian.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/cdefs.h>
#include <sys/user.h>
#include <time.h>
#include <unistd.h>
#include <unordered_map>
#include <cutils/properties.h>
#include <private/android_logger.h>
#include "LogBuffer.h"
#include "LogKlog.h"
#include "LogReader.h"
#include "LogUtils.h"
#ifndef __predict_false
#define __predict_false(exp) __builtin_expect((exp) != 0, 0)
#endif
// Default
#define log_buffer_size(id) mMaxSize[id]
const log_time LogBuffer::pruneMargin(3, 0);
void LogBuffer::init() {
log_id_for_each(i) {
mLastSet[i] = false;
mLast[i] = mLogElements.begin();
if (setSize(i, __android_logger_get_buffer_size(i))) {
setSize(i, LOG_BUFFER_MIN_SIZE);
}
}
bool lastMonotonic = monotonic;
monotonic = android_log_clockid() == CLOCK_MONOTONIC;
if (lastMonotonic != monotonic) {
//
// Fixup all timestamps, may not be 100% accurate, but better than
// throwing what we have away when we get 'surprised' by a change.
// In-place element fixup so no need to check reader-lock. Entries
// should already be in timestamp order, but we could end up with a
// few out-of-order entries if new monotonics come in before we
// are notified of the reinit change in status. A Typical example would
// be:
// --------- beginning of system
// 10.494082 184 201 D Cryptfs : Just triggered post_fs_data
// --------- beginning of kernel
// 0.000000 0 0 I : Initializing cgroup subsys
// as the act of mounting /data would trigger persist.logd.timestamp to
// be corrected. 1/30 corner case YMMV.
//
rdlock();
LogBufferElementCollection::iterator it = mLogElements.begin();
while ((it != mLogElements.end())) {
LogBufferElement* e = *it;
if (monotonic) {
if (!android::isMonotonic(e->mRealTime)) {
LogKlog::convertRealToMonotonic(e->mRealTime);
if ((e->mRealTime.tv_nsec % 1000) == 0) {
e->mRealTime.tv_nsec++;
}
}
} else {
if (android::isMonotonic(e->mRealTime)) {
LogKlog::convertMonotonicToReal(e->mRealTime);
if ((e->mRealTime.tv_nsec % 1000) == 0) {
e->mRealTime.tv_nsec++;
}
}
}
++it;
}
unlock();
}
// We may have been triggered by a SIGHUP. Release any sleeping reader
// threads to dump their current content.
//
// NB: this is _not_ performed in the context of a SIGHUP, it is
// performed during startup, and in context of reinit administrative thread
LogTimeEntry::wrlock();
LastLogTimes::iterator times = mTimes.begin();
while (times != mTimes.end()) {
LogTimeEntry* entry = times->get();
entry->triggerReader_Locked();
times++;
}
LogTimeEntry::unlock();
}
LogBuffer::LogBuffer(LastLogTimes* times)
: monotonic(android_log_clockid() == CLOCK_MONOTONIC), mTimes(*times) {
pthread_rwlock_init(&mLogElementsLock, nullptr);
log_id_for_each(i) {
lastLoggedElements[i] = nullptr;
droppedElements[i] = nullptr;
}
init();
}
LogBuffer::~LogBuffer() {
log_id_for_each(i) {
delete lastLoggedElements[i];
delete droppedElements[i];
}
}
enum match_type { DIFFERENT, SAME, SAME_LIBLOG };
static enum match_type identical(LogBufferElement* elem,
LogBufferElement* last) {
// is it mostly identical?
// if (!elem) return DIFFERENT;
ssize_t lenl = elem->getMsgLen();
if (lenl <= 0) return DIFFERENT; // value if this represents a chatty elem
// if (!last) return DIFFERENT;
ssize_t lenr = last->getMsgLen();
if (lenr <= 0) return DIFFERENT; // value if this represents a chatty elem
// if (elem->getLogId() != last->getLogId()) return DIFFERENT;
if (elem->getUid() != last->getUid()) return DIFFERENT;
if (elem->getPid() != last->getPid()) return DIFFERENT;
if (elem->getTid() != last->getTid()) return DIFFERENT;
// last is more than a minute old, stop squashing identical messages
if (elem->getRealTime().nsec() >
(last->getRealTime().nsec() + 60 * NS_PER_SEC))
return DIFFERENT;
// Identical message
const char* msgl = elem->getMsg();
const char* msgr = last->getMsg();
if (lenl == lenr) {
if (!fastcmp<memcmp>(msgl, msgr, lenl)) return SAME;
// liblog tagged messages (content gets summed)
if ((elem->getLogId() == LOG_ID_EVENTS) &&
(lenl == sizeof(android_log_event_int_t)) &&
!fastcmp<memcmp>(msgl, msgr, sizeof(android_log_event_int_t) -
sizeof(int32_t)) &&
(elem->getTag() == LIBLOG_LOG_TAG)) {
return SAME_LIBLOG;
}
}
// audit message (except sequence number) identical?
if (last->isBinary() &&
(lenl > static_cast<ssize_t>(sizeof(android_log_event_string_t))) &&
(lenr > static_cast<ssize_t>(sizeof(android_log_event_string_t)))) {
if (fastcmp<memcmp>(msgl, msgr, sizeof(android_log_event_string_t) -
sizeof(int32_t))) {
return DIFFERENT;
}
msgl += sizeof(android_log_event_string_t);
lenl -= sizeof(android_log_event_string_t);
msgr += sizeof(android_log_event_string_t);
lenr -= sizeof(android_log_event_string_t);
}
static const char avc[] = "): avc: ";
const char* avcl = android::strnstr(msgl, lenl, avc);
if (!avcl) return DIFFERENT;
lenl -= avcl - msgl;
const char* avcr = android::strnstr(msgr, lenr, avc);
if (!avcr) return DIFFERENT;
lenr -= avcr - msgr;
if (lenl != lenr) return DIFFERENT;
if (fastcmp<memcmp>(avcl + strlen(avc), avcr + strlen(avc),
lenl - strlen(avc))) {
return DIFFERENT;
}
return SAME;
}
int LogBuffer::log(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid,
pid_t tid, const char* msg, uint16_t len) {
if (log_id >= LOG_ID_MAX) {
return -EINVAL;
}
// Slip the time by 1 nsec if the incoming lands on xxxxxx000 ns.
// This prevents any chance that an outside source can request an
// exact entry with time specified in ms or us precision.
if ((realtime.tv_nsec % 1000) == 0) ++realtime.tv_nsec;
LogBufferElement* elem =
new LogBufferElement(log_id, realtime, uid, pid, tid, msg, len);
if (log_id != LOG_ID_SECURITY) {
int prio = ANDROID_LOG_INFO;
const char* tag = nullptr;
size_t tag_len = 0;
if (log_id == LOG_ID_EVENTS || log_id == LOG_ID_STATS) {
tag = tagToName(elem->getTag());
if (tag) {
tag_len = strlen(tag);
}
} else {
prio = *msg;
tag = msg + 1;
tag_len = strnlen(tag, len - 1);
}
if (!__android_log_is_loggable_len(prio, tag, tag_len,
ANDROID_LOG_VERBOSE)) {
// Log traffic received to total
wrlock();
stats.addTotal(elem);
unlock();
delete elem;
return -EACCES;
}
}
wrlock();
LogBufferElement* currentLast = lastLoggedElements[log_id];
if (currentLast) {
LogBufferElement* dropped = droppedElements[log_id];
uint16_t count = dropped ? dropped->getDropped() : 0;
//
// State Init
// incoming:
// dropped = nullptr
// currentLast = nullptr;
// elem = incoming message
// outgoing:
// dropped = nullptr -> State 0
// currentLast = copy of elem
// log elem
// State 0
// incoming:
// count = 0
// dropped = nullptr
// currentLast = copy of last message
// elem = incoming message
// outgoing: if match != DIFFERENT
// dropped = copy of first identical message -> State 1
// currentLast = reference to elem
// break: if match == DIFFERENT
// dropped = nullptr -> State 0
// delete copy of last message (incoming currentLast)
// currentLast = copy of elem
// log elem
// State 1
// incoming:
// count = 0
// dropped = copy of first identical message
// currentLast = reference to last held-back incoming
// message
// elem = incoming message
// outgoing: if match == SAME
// delete copy of first identical message (dropped)
// dropped = reference to last held-back incoming
// message set to chatty count of 1 -> State 2
// currentLast = reference to elem
// outgoing: if match == SAME_LIBLOG
// dropped = copy of first identical message -> State 1
// take sum of currentLast and elem
// if sum overflows:
// log currentLast
// currentLast = reference to elem
// else
// delete currentLast
// currentLast = reference to elem, sum liblog.
// break: if match == DIFFERENT
// delete dropped
// dropped = nullptr -> State 0
// log reference to last held-back (currentLast)
// currentLast = copy of elem
// log elem
// State 2
// incoming:
// count = chatty count
// dropped = chatty message holding count
// currentLast = reference to last held-back incoming
// message.
// dropped = chatty message holding count
// elem = incoming message
// outgoing: if match != DIFFERENT
// delete chatty message holding count
// dropped = reference to last held-back incoming
// message, set to chatty count + 1
// currentLast = reference to elem
// break: if match == DIFFERENT
// log dropped (chatty message)
// dropped = nullptr -> State 0
// log reference to last held-back (currentLast)
// currentLast = copy of elem
// log elem
//
enum match_type match = identical(elem, currentLast);
if (match != DIFFERENT) {
if (dropped) {
// Sum up liblog tag messages?
if ((count == 0) /* at Pass 1 */ && (match == SAME_LIBLOG)) {
android_log_event_int_t* event =
reinterpret_cast<android_log_event_int_t*>(
const_cast<char*>(currentLast->getMsg()));
//
// To unit test, differentiate with something like:
// event->header.tag = htole32(CHATTY_LOG_TAG);
// here, then instead of delete currentLast below,
// log(currentLast) to see the incremental sums form.
//
uint32_t swab = event->payload.data;
unsigned long long total = htole32(swab);
event = reinterpret_cast<android_log_event_int_t*>(
const_cast<char*>(elem->getMsg()));
swab = event->payload.data;
lastLoggedElements[LOG_ID_EVENTS] = elem;
total += htole32(swab);
// check for overflow
if (total >= UINT32_MAX) {
log(currentLast);
unlock();
return len;
}
stats.addTotal(currentLast);
delete currentLast;
swab = total;
event->payload.data = htole32(swab);
unlock();
return len;
}
if (count == USHRT_MAX) {
log(dropped);
count = 1;
} else {
delete dropped;
++count;
}
}
if (count) {
stats.addTotal(currentLast);
currentLast->setDropped(count);
}
droppedElements[log_id] = currentLast;
lastLoggedElements[log_id] = elem;
unlock();
return len;
}
if (dropped) { // State 1 or 2
if (count) { // State 2
log(dropped); // report chatty
} else { // State 1
delete dropped;
}
droppedElements[log_id] = nullptr;
log(currentLast); // report last message in the series
} else { // State 0
delete currentLast;
}
}
lastLoggedElements[log_id] = new LogBufferElement(*elem);
log(elem);
unlock();
return len;
}
// assumes LogBuffer::wrlock() held, owns elem, look after garbage collection
void LogBuffer::log(LogBufferElement* elem) {
// cap on how far back we will sort in-place, otherwise append
static uint32_t too_far_back = 5; // five seconds
// Insert elements in time sorted order if possible
// NB: if end is region locked, place element at end of list
LogBufferElementCollection::iterator it = mLogElements.end();
LogBufferElementCollection::iterator last = it;
if (__predict_true(it != mLogElements.begin())) --it;
if (__predict_false(it == mLogElements.begin()) ||
__predict_true((*it)->getRealTime() <= elem->getRealTime()) ||
__predict_false((((*it)->getRealTime().tv_sec - too_far_back) >
elem->getRealTime().tv_sec) &&
(elem->getLogId() != LOG_ID_KERNEL) &&
((*it)->getLogId() != LOG_ID_KERNEL))) {
mLogElements.push_back(elem);
} else {
log_time end(log_time::EPOCH);
bool end_set = false;
bool end_always = false;
LogTimeEntry::rdlock();
LastLogTimes::iterator times = mTimes.begin();
while (times != mTimes.end()) {
LogTimeEntry* entry = times->get();
if (!entry->mNonBlock) {
end_always = true;
break;
}
// it passing mEnd is blocked by the following checks.
if (!end_set || (end <= entry->mEnd)) {
end = entry->mEnd;
end_set = true;
}
times++;
}
if (end_always || (end_set && (end > (*it)->getRealTime()))) {
mLogElements.push_back(elem);
} else {
// should be short as timestamps are localized near end()
do {
last = it;
if (__predict_false(it == mLogElements.begin())) {
break;
}
--it;
} while (((*it)->getRealTime() > elem->getRealTime()) &&
(!end_set || (end <= (*it)->getRealTime())));
mLogElements.insert(last, elem);
}
LogTimeEntry::unlock();
}
stats.add(elem);
maybePrune(elem->getLogId());
}
// Prune at most 10% of the log entries or maxPrune, whichever is less.
//
// LogBuffer::wrlock() must be held when this function is called.
void LogBuffer::maybePrune(log_id_t id) {
size_t sizes = stats.sizes(id);
unsigned long maxSize = log_buffer_size(id);
if (sizes > maxSize) {
size_t sizeOver = sizes - ((maxSize * 9) / 10);
size_t elements = stats.realElements(id);
size_t minElements = elements / 100;
if (minElements < minPrune) {
minElements = minPrune;
}
unsigned long pruneRows = elements * sizeOver / sizes;
if (pruneRows < minElements) {
pruneRows = minElements;
}
if (pruneRows > maxPrune) {
pruneRows = maxPrune;
}
prune(id, pruneRows);
}
}
LogBufferElementCollection::iterator LogBuffer::erase(
LogBufferElementCollection::iterator it, bool coalesce) {
LogBufferElement* element = *it;
log_id_t id = element->getLogId();
// Remove iterator references in the various lists that will become stale
// after the element is erased from the main logging list.
{ // start of scope for found iterator
int key = ((id == LOG_ID_EVENTS) || (id == LOG_ID_SECURITY))
? element->getTag()
: element->getUid();
LogBufferIteratorMap::iterator found = mLastWorst[id].find(key);
if ((found != mLastWorst[id].end()) && (it == found->second)) {
mLastWorst[id].erase(found);
}
}
{ // start of scope for pid found iterator
// element->getUid() may not be AID_SYSTEM for next-best-watermark.
// will not assume id != LOG_ID_EVENTS or LOG_ID_SECURITY for KISS and
// long term code stability, find() check should be fast for those ids.
LogBufferPidIteratorMap::iterator found =
mLastWorstPidOfSystem[id].find(element->getPid());
if ((found != mLastWorstPidOfSystem[id].end()) &&
(it == found->second)) {
mLastWorstPidOfSystem[id].erase(found);
}
}
bool setLast[LOG_ID_MAX];
bool doSetLast = false;
log_id_for_each(i) {
doSetLast |= setLast[i] = mLastSet[i] && (it == mLast[i]);
}
#ifdef DEBUG_CHECK_FOR_STALE_ENTRIES
LogBufferElementCollection::iterator bad = it;
int key = ((id == LOG_ID_EVENTS) || (id == LOG_ID_SECURITY))
? element->getTag()
: element->getUid();
#endif
it = mLogElements.erase(it);
if (doSetLast) {
log_id_for_each(i) {
if (setLast[i]) {
if (__predict_false(it == mLogElements.end())) { // impossible
mLastSet[i] = false;
mLast[i] = mLogElements.begin();
} else {
mLast[i] = it; // push down the road as next-best-watermark
}
}
}
}
#ifdef DEBUG_CHECK_FOR_STALE_ENTRIES
log_id_for_each(i) {
for (auto b : mLastWorst[i]) {
if (bad == b.second) {
android::prdebug("stale mLastWorst[%d] key=%d mykey=%d\n", i,
b.first, key);
}
}
for (auto b : mLastWorstPidOfSystem[i]) {
if (bad == b.second) {
android::prdebug("stale mLastWorstPidOfSystem[%d] pid=%d\n", i,
b.first);
}
}
if (mLastSet[i] && (bad == mLast[i])) {
android::prdebug("stale mLast[%d]\n", i);
mLastSet[i] = false;
mLast[i] = mLogElements.begin();
}
}
#endif
if (coalesce) {
stats.erase(element);
} else {
stats.subtract(element);
}
delete element;
return it;
}
// Define a temporary mechanism to report the last LogBufferElement pointer
// for the specified uid, pid and tid. Used below to help merge-sort when
// pruning for worst UID.
class LogBufferElementKey {
const union {
struct {
uint32_t uid;
uint16_t pid;
uint16_t tid;
} __packed;
uint64_t value;
} __packed;
public:
LogBufferElementKey(uid_t uid, pid_t pid, pid_t tid)
: uid(uid), pid(pid), tid(tid) {
}
explicit LogBufferElementKey(uint64_t key) : value(key) {
}
uint64_t getKey() {
return value;
}
};
class LogBufferElementLast {
typedef std::unordered_map<uint64_t, LogBufferElement*> LogBufferElementMap;
LogBufferElementMap map;
public:
bool coalesce(LogBufferElement* element, uint16_t dropped) {
LogBufferElementKey key(element->getUid(), element->getPid(),
element->getTid());
LogBufferElementMap::iterator it = map.find(key.getKey());
if (it != map.end()) {
LogBufferElement* found = it->second;
uint16_t moreDropped = found->getDropped();
if ((dropped + moreDropped) > USHRT_MAX) {
map.erase(it);
} else {
found->setDropped(dropped + moreDropped);
return true;
}
}
return false;
}
void add(LogBufferElement* element) {
LogBufferElementKey key(element->getUid(), element->getPid(),
element->getTid());
map[key.getKey()] = element;
}
inline void clear() {
map.clear();
}
void clear(LogBufferElement* element) {
log_time current =
element->getRealTime() - log_time(EXPIRE_RATELIMIT, 0);
for (LogBufferElementMap::iterator it = map.begin(); it != map.end();) {
LogBufferElement* mapElement = it->second;
if ((mapElement->getDropped() >= EXPIRE_THRESHOLD) &&
(current > mapElement->getRealTime())) {
it = map.erase(it);
} else {
++it;
}
}
}
};
// Determine if watermark is within pruneMargin + 1s from the end of the list,
// the caller will use this result to set an internal busy flag indicating
// the prune operation could not be completed because a reader is blocking
// the request.
bool LogBuffer::isBusy(log_time watermark) {
LogBufferElementCollection::iterator ei = mLogElements.end();
--ei;
return watermark < ((*ei)->getRealTime() - pruneMargin - log_time(1, 0));
}
// If the selected reader is blocking our pruning progress, decide on
// what kind of mitigation is necessary to unblock the situation.
void LogBuffer::kickMe(LogTimeEntry* me, log_id_t id, unsigned long pruneRows) {
if (stats.sizes(id) > (2 * log_buffer_size(id))) { // +100%
// A misbehaving or slow reader has its connection
// dropped if we hit too much memory pressure.
me->release_Locked();
} else if (me->mTimeout.tv_sec || me->mTimeout.tv_nsec) {
// Allow a blocked WRAP timeout reader to
// trigger and start reporting the log data.
me->triggerReader_Locked();
} else {
// tell slow reader to skip entries to catch up
me->triggerSkip_Locked(id, pruneRows);
}
}
// prune "pruneRows" of type "id" from the buffer.
//
// This garbage collection task is used to expire log entries. It is called to
// remove all logs (clear), all UID logs (unprivileged clear), or every
// 256 or 10% of the total logs (whichever is less) to prune the logs.
//
// First there is a prep phase where we discover the reader region lock that
// acts as a backstop to any pruning activity to stop there and go no further.
//
// There are three major pruning loops that follow. All expire from the oldest
// entries. Since there are multiple log buffers, the Android logging facility
// will appear to drop entries 'in the middle' when looking at multiple log
// sources and buffers. This effect is slightly more prominent when we prune
// the worst offender by logging source. Thus the logs slowly loose content
// and value as you move back in time. This is preferred since chatty sources
// invariably move the logs value down faster as less chatty sources would be
// expired in the noise.
//
// The first loop performs blacklisting and worst offender pruning. Falling
// through when there are no notable worst offenders and have not hit the
// region lock preventing further worst offender pruning. This loop also looks
// after managing the chatty log entries and merging to help provide
// statistical basis for blame. The chatty entries are not a notification of
// how much logs you may have, but instead represent how much logs you would
// have had in a virtual log buffer that is extended to cover all the in-memory
// logs without loss. They last much longer than the represented pruned logs
// since they get multiplied by the gains in the non-chatty log sources.
//
// The second loop get complicated because an algorithm of watermarks and
// history is maintained to reduce the order and keep processing time
// down to a minimum at scale. These algorithms can be costly in the face
// of larger log buffers, or severly limited processing time granted to a
// background task at lowest priority.
//
// This second loop does straight-up expiration from the end of the logs
// (again, remember for the specified log buffer id) but does some whitelist
// preservation. Thus whitelist is a Hail Mary low priority, blacklists and
// spam filtration all take priority. This second loop also checks if a region
// lock is causing us to buffer too much in the logs to help the reader(s),
// and will tell the slowest reader thread to skip log entries, and if
// persistent and hits a further threshold, kill the reader thread.
//
// The third thread is optional, and only gets hit if there was a whitelist
// and more needs to be pruned against the backstop of the region lock.
//
// LogBuffer::wrlock() must be held when this function is called.
//
bool LogBuffer::prune(log_id_t id, unsigned long pruneRows, uid_t caller_uid) {
LogTimeEntry* oldest = nullptr;
bool busy = false;
bool clearAll = pruneRows == ULONG_MAX;
LogTimeEntry::rdlock();
// Region locked?
LastLogTimes::iterator times = mTimes.begin();
while (times != mTimes.end()) {
LogTimeEntry* entry = times->get();
if (entry->isWatching(id) &&
(!oldest || (oldest->mStart > entry->mStart) ||
((oldest->mStart == entry->mStart) &&
(entry->mTimeout.tv_sec || entry->mTimeout.tv_nsec)))) {
oldest = entry;
}
times++;
}
log_time watermark(log_time::tv_sec_max, log_time::tv_nsec_max);
if (oldest) watermark = oldest->mStart - pruneMargin;
LogBufferElementCollection::iterator it;
if (__predict_false(caller_uid != AID_ROOT)) { // unlikely
// Only here if clear all request from non system source, so chatty
// filter logistics is not required.
it = mLastSet[id] ? mLast[id] : mLogElements.begin();
while (it != mLogElements.end()) {
LogBufferElement* element = *it;
if ((element->getLogId() != id) ||
(element->getUid() != caller_uid)) {
++it;
continue;
}
if (!mLastSet[id] || ((*mLast[id])->getLogId() != id)) {
mLast[id] = it;
mLastSet[id] = true;
}
if (oldest && (watermark <= element->getRealTime())) {
busy = isBusy(watermark);
if (busy) kickMe(oldest, id, pruneRows);
break;
}
it = erase(it);
if (--pruneRows == 0) {
break;
}
}
LogTimeEntry::unlock();
return busy;
}
// prune by worst offenders; by blacklist, UID, and by PID of system UID
bool hasBlacklist = (id != LOG_ID_SECURITY) && mPrune.naughty();
while (!clearAll && (pruneRows > 0)) {
// recalculate the worst offender on every batched pass
int worst = -1; // not valid for getUid() or getKey()
size_t worst_sizes = 0;
size_t second_worst_sizes = 0;
pid_t worstPid = 0; // POSIX guarantees PID != 0
if (worstUidEnabledForLogid(id) && mPrune.worstUidEnabled()) {
// Calculate threshold as 12.5% of available storage
size_t threshold = log_buffer_size(id) / 8;
if ((id == LOG_ID_EVENTS) || (id == LOG_ID_SECURITY)) {
stats.sortTags(AID_ROOT, (pid_t)0, 2, id)
.findWorst(worst, worst_sizes, second_worst_sizes,
threshold);
// per-pid filter for AID_SYSTEM sources is too complex
} else {
stats.sort(AID_ROOT, (pid_t)0, 2, id)
.findWorst(worst, worst_sizes, second_worst_sizes,
threshold);
if ((worst == AID_SYSTEM) && mPrune.worstPidOfSystemEnabled()) {
stats.sortPids(worst, (pid_t)0, 2, id)
.findWorst(worstPid, worst_sizes, second_worst_sizes);
}
}
}
// skip if we have neither worst nor naughty filters
if ((worst == -1) && !hasBlacklist) {
break;
}
bool kick = false;
bool leading = true;
it = mLastSet[id] ? mLast[id] : mLogElements.begin();
// Perform at least one mandatory garbage collection cycle in following
// - clear leading chatty tags
// - coalesce chatty tags
// - check age-out of preserved logs
bool gc = pruneRows <= 1;
if (!gc && (worst != -1)) {
{ // begin scope for worst found iterator
LogBufferIteratorMap::iterator found =
mLastWorst[id].find(worst);
if ((found != mLastWorst[id].end()) &&
(found->second != mLogElements.end())) {
leading = false;
it = found->second;
}
}
if (worstPid) { // begin scope for pid worst found iterator
// FYI: worstPid only set if !LOG_ID_EVENTS and
// !LOG_ID_SECURITY, not going to make that assumption ...
LogBufferPidIteratorMap::iterator found =
mLastWorstPidOfSystem[id].find(worstPid);
if ((found != mLastWorstPidOfSystem[id].end()) &&
(found->second != mLogElements.end())) {
leading = false;
it = found->second;
}
}
}
static const timespec too_old = { EXPIRE_HOUR_THRESHOLD * 60 * 60, 0 };
LogBufferElementCollection::iterator lastt;
lastt = mLogElements.end();
--lastt;
LogBufferElementLast last;
while (it != mLogElements.end()) {
LogBufferElement* element = *it;
if (oldest && (watermark <= element->getRealTime())) {
busy = isBusy(watermark);
// Do not let chatty eliding trigger any reader mitigation
break;
}
if (element->getLogId() != id) {
++it;
continue;
}
// below this point element->getLogId() == id
if (leading && (!mLastSet[id] || ((*mLast[id])->getLogId() != id))) {
mLast[id] = it;
mLastSet[id] = true;
}
uint16_t dropped = element->getDropped();
// remove any leading drops
if (leading && dropped) {
it = erase(it);
continue;
}
if (dropped && last.coalesce(element, dropped)) {
it = erase(it, true);
continue;
}
int key = ((id == LOG_ID_EVENTS) || (id == LOG_ID_SECURITY))
? element->getTag()
: element->getUid();
if (hasBlacklist && mPrune.naughty(element)) {
last.clear(element);
it = erase(it);
if (dropped) {
continue;
}
pruneRows--;
if (pruneRows == 0) {
break;
}
if (key == worst) {
kick = true;
if (worst_sizes < second_worst_sizes) {
break;
}
worst_sizes -= element->getMsgLen();
}
continue;
}
if ((element->getRealTime() < ((*lastt)->getRealTime() - too_old)) ||
(element->getRealTime() > (*lastt)->getRealTime())) {
break;
}
if (dropped) {
last.add(element);
if (worstPid &&
((!gc && (element->getPid() == worstPid)) ||
(mLastWorstPidOfSystem[id].find(element->getPid()) ==
mLastWorstPidOfSystem[id].end()))) {
// element->getUid() may not be AID_SYSTEM, next best
// watermark if current one empty. id is not LOG_ID_EVENTS
// or LOG_ID_SECURITY because of worstPid check.
mLastWorstPidOfSystem[id][element->getPid()] = it;
}
if ((!gc && !worstPid && (key == worst)) ||
(mLastWorst[id].find(key) == mLastWorst[id].end())) {
mLastWorst[id][key] = it;
}
++it;
continue;
}
if ((key != worst) ||
(worstPid && (element->getPid() != worstPid))) {
leading = false;
last.clear(element);
++it;
continue;
}
// key == worst below here
// If worstPid set, then element->getPid() == worstPid below here
pruneRows--;
if (pruneRows == 0) {
break;
}
kick = true;
uint16_t len = element->getMsgLen();
// do not create any leading drops
if (leading) {
it = erase(it);
} else {
stats.drop(element);
element->setDropped(1);
if (last.coalesce(element, 1)) {
it = erase(it, true);
} else {
last.add(element);
if (worstPid &&
(!gc || (mLastWorstPidOfSystem[id].find(worstPid) ==
mLastWorstPidOfSystem[id].end()))) {
// element->getUid() may not be AID_SYSTEM, next best
// watermark if current one empty. id is not
// LOG_ID_EVENTS or LOG_ID_SECURITY because of worstPid.
mLastWorstPidOfSystem[id][worstPid] = it;
}
if ((!gc && !worstPid) ||
(mLastWorst[id].find(worst) == mLastWorst[id].end())) {
mLastWorst[id][worst] = it;
}
++it;
}
}
if (worst_sizes < second_worst_sizes) {
break;
}
worst_sizes -= len;
}
last.clear();
if (!kick || !mPrune.worstUidEnabled()) {
break; // the following loop will ask bad clients to skip/drop
}
}
bool whitelist = false;
bool hasWhitelist = (id != LOG_ID_SECURITY) && mPrune.nice() && !clearAll;
it = mLastSet[id] ? mLast[id] : mLogElements.begin();
while ((pruneRows > 0) && (it != mLogElements.end())) {
LogBufferElement* element = *it;
if (element->getLogId() != id) {
it++;
continue;
}
if (!mLastSet[id] || ((*mLast[id])->getLogId() != id)) {
mLast[id] = it;
mLastSet[id] = true;
}
if (oldest && (watermark <= element->getRealTime())) {
busy = isBusy(watermark);
if (!whitelist && busy) kickMe(oldest, id, pruneRows);
break;
}
if (hasWhitelist && !element->getDropped() && mPrune.nice(element)) {
// WhiteListed
whitelist = true;
it++;
continue;
}
it = erase(it);
pruneRows--;
}
// Do not save the whitelist if we are reader range limited
if (whitelist && (pruneRows > 0)) {
it = mLastSet[id] ? mLast[id] : mLogElements.begin();
while ((it != mLogElements.end()) && (pruneRows > 0)) {
LogBufferElement* element = *it;
if (element->getLogId() != id) {
++it;
continue;
}
if (!mLastSet[id] || ((*mLast[id])->getLogId() != id)) {
mLast[id] = it;
mLastSet[id] = true;
}
if (oldest && (watermark <= element->getRealTime())) {
busy = isBusy(watermark);
if (busy) kickMe(oldest, id, pruneRows);
break;
}
it = erase(it);
pruneRows--;
}
}
LogTimeEntry::unlock();
return (pruneRows > 0) && busy;
}
// clear all rows of type "id" from the buffer.
bool LogBuffer::clear(log_id_t id, uid_t uid) {
bool busy = true;
// If it takes more than 4 tries (seconds) to clear, then kill reader(s)
for (int retry = 4;;) {
if (retry == 1) { // last pass
// Check if it is still busy after the sleep, we say prune
// one entry, not another clear run, so we are looking for
// the quick side effect of the return value to tell us if
// we have a _blocked_ reader.
wrlock();
busy = prune(id, 1, uid);
unlock();
// It is still busy, blocked reader(s), lets kill them all!
// otherwise, lets be a good citizen and preserve the slow
// readers and let the clear run (below) deal with determining
// if we are still blocked and return an error code to caller.
if (busy) {
LogTimeEntry::wrlock();
LastLogTimes::iterator times = mTimes.begin();
while (times != mTimes.end()) {
LogTimeEntry* entry = times->get();
// Killer punch
if (entry->isWatching(id)) {
entry->release_Locked();
}
times++;
}
LogTimeEntry::unlock();
}
}
wrlock();
busy = prune(id, ULONG_MAX, uid);
unlock();
if (!busy || !--retry) {
break;
}
sleep(1); // Let reader(s) catch up after notification
}
return busy;
}
// get the used space associated with "id".
unsigned long LogBuffer::getSizeUsed(log_id_t id) {
rdlock();
size_t retval = stats.sizes(id);
unlock();
return retval;
}
// set the total space allocated to "id"
int LogBuffer::setSize(log_id_t id, unsigned long size) {
// Reasonable limits ...
if (!__android_logger_valid_buffer_size(size)) {
return -1;
}
wrlock();
log_buffer_size(id) = size;
unlock();
return 0;
}
// get the total space allocated to "id"
unsigned long LogBuffer::getSize(log_id_t id) {
rdlock();
size_t retval = log_buffer_size(id);
unlock();
return retval;
}
log_time LogBuffer::flushTo(SocketClient* reader, const log_time& start,
pid_t* lastTid, bool privileged, bool security,
int (*filter)(const LogBufferElement* element,
void* arg),
void* arg) {
LogBufferElementCollection::iterator it;
uid_t uid = reader->getUid();
rdlock();
if (start == log_time::EPOCH) {
// client wants to start from the beginning
it = mLogElements.begin();
} else {
// Cap to 300 iterations we look back for out-of-order entries.
size_t count = 300;
// Client wants to start from some specified time. Chances are
// we are better off starting from the end of the time sorted list.
LogBufferElementCollection::iterator last;
for (last = it = mLogElements.end(); it != mLogElements.begin();
/* do nothing */) {
--it;
LogBufferElement* element = *it;
if (element->getRealTime() > start) {
last = it;
} else if (element->getRealTime() == start) {
last = ++it;
break;
} else if (!--count) {
break;
}
}
it = last;
}
log_time curr = start;
LogBufferElement* lastElement = nullptr; // iterator corruption paranoia
static const size_t maxSkip = 4194304; // maximum entries to skip
size_t skip = maxSkip;
for (; it != mLogElements.end(); ++it) {
LogBufferElement* element = *it;
if (!--skip) {
android::prdebug("reader.per: too many elements skipped");
break;
}
if (element == lastElement) {
android::prdebug("reader.per: identical elements");
break;
}
lastElement = element;
if (!privileged && (element->getUid() != uid)) {
continue;
}
if (!security && (element->getLogId() == LOG_ID_SECURITY)) {
continue;
}
// NB: calling out to another object with wrlock() held (safe)
if (filter) {
int ret = (*filter)(element, arg);
if (ret == false) {
continue;
}
if (ret != true) {
break;
}
}
bool sameTid = false;
if (lastTid) {
sameTid = lastTid[element->getLogId()] == element->getTid();
// Dropped (chatty) immediately following a valid log from the
// same source in the same log buffer indicates we have a
// multiple identical squash. chatty that differs source
// is due to spam filter. chatty to chatty of different
// source is also due to spam filter.
lastTid[element->getLogId()] =
(element->getDropped() && !sameTid) ? 0 : element->getTid();
}
unlock();
// range locking in LastLogTimes looks after us
curr = element->flushTo(reader, this, sameTid);
if (curr == element->FLUSH_ERROR) {
return curr;
}
skip = maxSkip;
rdlock();
}
unlock();
return curr;
}
std::string LogBuffer::formatStatistics(uid_t uid, pid_t pid,
unsigned int logMask) {
wrlock();
std::string ret = stats.format(uid, pid, logMask);
unlock();
return ret;
}
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