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platform_system_core/liblog/logger_write.c

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/*
* Copyright (C) 2007-2016 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 <errno.h>
#include <stdatomic.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#ifdef __BIONIC__
#include <android/set_abort_message.h>
#endif
#include <log/event_tag_map.h>
#include <private/android_filesystem_config.h>
#include <private/android_logger.h>
#include "config_write.h"
#include "log_portability.h"
#include "logger.h"
#define LOG_BUF_SIZE 1024
static int __write_to_log_init(log_id_t, struct iovec *vec, size_t nr);
static int (*write_to_log)(log_id_t, struct iovec *vec, size_t nr) = __write_to_log_init;
/*
* This is used by the C++ code to decide if it should write logs through
* the C code. Basically, if /dev/socket/logd is available, we're running in
* the simulator rather than a desktop tool and want to use the device.
*/
static enum {
kLogUninitialized, kLogNotAvailable, kLogAvailable
} g_log_status = kLogUninitialized;
static int check_log_uid_permissions()
{
#if defined(__ANDROID__)
uid_t uid = __android_log_uid();
/* Matches clientHasLogCredentials() in logd */
if ((uid != AID_SYSTEM) && (uid != AID_ROOT) && (uid != AID_LOG)) {
uid = geteuid();
if ((uid != AID_SYSTEM) && (uid != AID_ROOT) && (uid != AID_LOG)) {
gid_t gid = getgid();
if ((gid != AID_SYSTEM) &&
(gid != AID_ROOT) &&
(gid != AID_LOG)) {
gid = getegid();
if ((gid != AID_SYSTEM) &&
(gid != AID_ROOT) &&
(gid != AID_LOG)) {
int num_groups;
gid_t *groups;
num_groups = getgroups(0, NULL);
if (num_groups <= 0) {
return -EPERM;
}
groups = calloc(num_groups, sizeof(gid_t));
if (!groups) {
return -ENOMEM;
}
num_groups = getgroups(num_groups, groups);
while (num_groups > 0) {
if (groups[num_groups - 1] == AID_LOG) {
break;
}
--num_groups;
}
free(groups);
if (num_groups <= 0) {
return -EPERM;
}
}
}
}
}
#endif
return 0;
}
static void __android_log_cache_available(
struct android_log_transport_write *node)
{
size_t i;
if (node->logMask) {
return;
}
for (i = LOG_ID_MIN; i < LOG_ID_MAX; ++i) {
if (node->write &&
(i != LOG_ID_KERNEL) &&
((i != LOG_ID_SECURITY) ||
(check_log_uid_permissions() == 0)) &&
(!node->available || ((*node->available)(i) >= 0))) {
node->logMask |= 1 << i;
}
}
}
LIBLOG_ABI_PUBLIC int __android_log_dev_available()
{
struct android_log_transport_write *node;
if (list_empty(&__android_log_transport_write)) {
return kLogUninitialized;
}
write_transport_for_each(node, &__android_log_transport_write) {
__android_log_cache_available(node);
if (node->logMask) {
return kLogAvailable;
}
}
return kLogNotAvailable;
}
#if defined(__ANDROID__)
static atomic_uintptr_t tagMap;
#endif
/*
* Release any logger resources. A new log write will immediately re-acquire.
*/
LIBLOG_ABI_PUBLIC void __android_log_close()
{
struct android_log_transport_write *transport;
#if defined(__ANDROID__)
EventTagMap *m;
#endif
__android_log_lock();
write_to_log = __write_to_log_init;
/*
* Threads that are actively writing at this point are not held back
* by a lock and are at risk of dropping the messages with a return code
* -EBADF. Prefer to return error code than add the overhead of a lock to
* each log writing call to guarantee delivery. In addition, anyone
* calling this is doing so to release the logging resources and shut down,
* for them to do so with outstanding log requests in other threads is a
* disengenuous use of this function.
*/
write_transport_for_each(transport, &__android_log_persist_write) {
if (transport->close) {
(*transport->close)();
}
}
write_transport_for_each(transport, &__android_log_transport_write) {
if (transport->close) {
(*transport->close)();
}
}
#if defined(__ANDROID__)
/*
* Additional risk here somewhat mitigated by immediately unlock flushing
* the processor cache. The multi-threaded race that we choose to accept,
* to minimize locking, is an atomic_load in a writer picking up a value
* just prior to entering this routine. There will be an use after free.
*
* Again, anyone calling this is doing so to release the logging resources
* is most probably going to quiesce then shut down; or to restart after
* a fork so the risk should be non-existent. For this reason we
* choose a mitigation stance for efficiency instead of incuring the cost
* of a lock for every log write.
*/
m = (EventTagMap *)atomic_exchange(&tagMap, (uintptr_t)0);
#endif
__android_log_unlock();
#if defined(__ANDROID__)
if (m != (EventTagMap *)(uintptr_t)-1LL) android_closeEventTagMap(m);
#endif
}
/* log_init_lock assumed */
static int __write_to_log_initialize()
{
struct android_log_transport_write *transport;
struct listnode *n;
int i = 0, ret = 0;
__android_log_config_write();
write_transport_for_each_safe(transport, n, &__android_log_transport_write) {
__android_log_cache_available(transport);
if (!transport->logMask) {
list_remove(&transport->node);
continue;
}
if (!transport->open || ((*transport->open)() < 0)) {
if (transport->close) {
(*transport->close)();
}
list_remove(&transport->node);
continue;
}
++ret;
}
write_transport_for_each_safe(transport, n, &__android_log_persist_write) {
__android_log_cache_available(transport);
if (!transport->logMask) {
list_remove(&transport->node);
continue;
}
if (!transport->open || ((*transport->open)() < 0)) {
if (transport->close) {
(*transport->close)();
}
list_remove(&transport->node);
continue;
}
++i;
}
if (!ret && !i) {
return -ENODEV;
}
return ret;
}
/*
* Extract a 4-byte value from a byte stream. le32toh open coded
*/
static inline uint32_t get4LE(const uint8_t* src)
{
return src[0] | (src[1] << 8) | (src[2] << 16) | (src[3] << 24);
}
static int __write_to_log_daemon(log_id_t log_id, struct iovec *vec, size_t nr)
{
struct android_log_transport_write *node;
int ret;
struct timespec ts;
size_t len, i;
for (len = i = 0; i < nr; ++i) {
len += vec[i].iov_len;
}
if (!len) {
return -EINVAL;
}
#if defined(__ANDROID__)
clock_gettime(android_log_clockid(), &ts);
if (log_id == LOG_ID_SECURITY) {
if (vec[0].iov_len < 4) {
return -EINVAL;
}
ret = check_log_uid_permissions();
if (ret < 0) {
return ret;
}
if (!__android_log_security()) {
/* If only we could reset downstream logd counter */
return -EPERM;
}
} else if (log_id == LOG_ID_EVENTS) {
const char *tag;
size_t len;
EventTagMap *m, *f;
if (vec[0].iov_len < 4) {
return -EINVAL;
}
tag = NULL;
len = 0;
f = NULL;
m = (EventTagMap *)atomic_load(&tagMap);
if (!m) {
ret = __android_log_trylock();
m = (EventTagMap *)atomic_load(&tagMap); /* trylock flush cache */
if (!m) {
m = android_openEventTagMap(NULL);
if (ret) { /* trylock failed, use local copy, mark for close */
f = m;
} else {
if (!m) { /* One chance to open map file */
m = (EventTagMap *)(uintptr_t)-1LL;
}
atomic_store(&tagMap, (uintptr_t)m);
}
}
if (!ret) { /* trylock succeeded, unlock */
__android_log_unlock();
}
}
if (m && (m != (EventTagMap *)(uintptr_t)-1LL)) {
tag = android_lookupEventTag_len(m, &len, get4LE(vec[0].iov_base));
}
ret = __android_log_is_loggable_len(ANDROID_LOG_INFO,
tag, len,
ANDROID_LOG_VERBOSE);
if (f) { /* local copy marked for close */
android_closeEventTagMap(f);
}
if (!ret) {
return -EPERM;
}
} else {
/* Validate the incoming tag, tag content can not split across iovec */
char prio = ANDROID_LOG_VERBOSE;
const char *tag = vec[0].iov_base;
size_t len = vec[0].iov_len;
if (!tag) {
len = 0;
}
if (len > 0) {
prio = *tag;
if (len > 1) {
--len;
++tag;
} else {
len = vec[1].iov_len;
tag = ((const char *)vec[1].iov_base);
if (!tag) {
len = 0;
}
}
}
/* tag must be nul terminated */
if (strnlen(tag, len) >= len) {
tag = NULL;
}
if (!__android_log_is_loggable_len(prio,
tag, len - 1,
ANDROID_LOG_VERBOSE)) {
return -EPERM;
}
}
#else
/* simulate clock_gettime(CLOCK_REALTIME, &ts); */
{
struct timeval tv;
gettimeofday(&tv, NULL);
ts.tv_sec = tv.tv_sec;
ts.tv_nsec = tv.tv_usec * 1000;
}
#endif
ret = 0;
i = 1 << log_id;
write_transport_for_each(node, &__android_log_transport_write) {
if (node->logMask & i) {
ssize_t retval;
retval = (*node->write)(log_id, &ts, vec, nr);
if (ret >= 0) {
ret = retval;
}
}
}
write_transport_for_each(node, &__android_log_persist_write) {
if (node->logMask & i) {
(void)(*node->write)(log_id, &ts, vec, nr);
}
}
return ret;
}
static int __write_to_log_init(log_id_t log_id, struct iovec *vec, size_t nr)
{
__android_log_lock();
if (write_to_log == __write_to_log_init) {
int ret;
ret = __write_to_log_initialize();
if (ret < 0) {
__android_log_unlock();
if (!list_empty(&__android_log_persist_write)) {
__write_to_log_daemon(log_id, vec, nr);
}
return ret;
}
write_to_log = __write_to_log_daemon;
}
__android_log_unlock();
return write_to_log(log_id, vec, nr);
}
LIBLOG_ABI_PUBLIC int __android_log_write(int prio, const char *tag,
const char *msg)
{
return __android_log_buf_write(LOG_ID_MAIN, prio, tag, msg);
}
LIBLOG_ABI_PUBLIC int __android_log_buf_write(int bufID, int prio,
const char *tag, const char *msg)
{
struct iovec vec[3];
char tmp_tag[32];
if (!tag)
tag = "";
/* XXX: This needs to go! */
if ((bufID != LOG_ID_RADIO) &&
(!strcmp(tag, "HTC_RIL") ||
!strncmp(tag, "RIL", 3) || /* Any log tag with "RIL" as the prefix */
!strncmp(tag, "IMS", 3) || /* Any log tag with "IMS" as the prefix */
!strcmp(tag, "AT") ||
!strcmp(tag, "GSM") ||
!strcmp(tag, "STK") ||
!strcmp(tag, "CDMA") ||
!strcmp(tag, "PHONE") ||
!strcmp(tag, "SMS"))) {
bufID = LOG_ID_RADIO;
/* Inform third party apps/ril/radio.. to use Rlog or RLOG */
snprintf(tmp_tag, sizeof(tmp_tag), "use-Rlog/RLOG-%s", tag);
tag = tmp_tag;
}
#if __BIONIC__
if (prio == ANDROID_LOG_FATAL) {
android_set_abort_message(msg);
}
#endif
vec[0].iov_base = (unsigned char *)&prio;
vec[0].iov_len = 1;
vec[1].iov_base = (void *)tag;
vec[1].iov_len = strlen(tag) + 1;
vec[2].iov_base = (void *)msg;
vec[2].iov_len = strlen(msg) + 1;
return write_to_log(bufID, vec, 3);
}
LIBLOG_ABI_PUBLIC int __android_log_vprint(int prio, const char *tag,
const char *fmt, va_list ap)
{
char buf[LOG_BUF_SIZE];
vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
return __android_log_write(prio, tag, buf);
}
LIBLOG_ABI_PUBLIC int __android_log_print(int prio, const char *tag,
const char *fmt, ...)
{
va_list ap;
char buf[LOG_BUF_SIZE];
va_start(ap, fmt);
vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
va_end(ap);
return __android_log_write(prio, tag, buf);
}
LIBLOG_ABI_PUBLIC int __android_log_buf_print(int bufID, int prio,
const char *tag,
const char *fmt, ...)
{
va_list ap;
char buf[LOG_BUF_SIZE];
va_start(ap, fmt);
vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
va_end(ap);
return __android_log_buf_write(bufID, prio, tag, buf);
}
LIBLOG_ABI_PUBLIC void __android_log_assert(const char *cond, const char *tag,
const char *fmt, ...)
{
char buf[LOG_BUF_SIZE];
if (fmt) {
va_list ap;
va_start(ap, fmt);
vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
va_end(ap);
} else {
/* Msg not provided, log condition. N.B. Do not use cond directly as
* format string as it could contain spurious '%' syntax (e.g.
* "%d" in "blocks%devs == 0").
*/
if (cond)
snprintf(buf, LOG_BUF_SIZE, "Assertion failed: %s", cond);
else
strcpy(buf, "Unspecified assertion failed");
}
__android_log_write(ANDROID_LOG_FATAL, tag, buf);
abort(); /* abort so we have a chance to debug the situation */
/* NOTREACHED */
}
LIBLOG_ABI_PUBLIC int __android_log_bwrite(int32_t tag,
const void *payload, size_t len)
{
struct iovec vec[2];
vec[0].iov_base = &tag;
vec[0].iov_len = sizeof(tag);
vec[1].iov_base = (void*)payload;
vec[1].iov_len = len;
return write_to_log(LOG_ID_EVENTS, vec, 2);
}
LIBLOG_ABI_PUBLIC int __android_log_security_bwrite(int32_t tag,
const void *payload,
size_t len)
{
struct iovec vec[2];
vec[0].iov_base = &tag;
vec[0].iov_len = sizeof(tag);
vec[1].iov_base = (void*)payload;
vec[1].iov_len = len;
return write_to_log(LOG_ID_SECURITY, vec, 2);
}
/*
* Like __android_log_bwrite, but takes the type as well. Doesn't work
* for the general case where we're generating lists of stuff, but very
* handy if we just want to dump an integer into the log.
*/
LIBLOG_ABI_PUBLIC int __android_log_btwrite(int32_t tag, char type,
const void *payload, size_t len)
{
struct iovec vec[3];
vec[0].iov_base = &tag;
vec[0].iov_len = sizeof(tag);
vec[1].iov_base = &type;
vec[1].iov_len = sizeof(type);
vec[2].iov_base = (void*)payload;
vec[2].iov_len = len;
return write_to_log(LOG_ID_EVENTS, vec, 3);
}
/*
* Like __android_log_bwrite, but used for writing strings to the
* event log.
*/
LIBLOG_ABI_PUBLIC int __android_log_bswrite(int32_t tag, const char *payload)
{
struct iovec vec[4];
char type = EVENT_TYPE_STRING;
uint32_t len = strlen(payload);
vec[0].iov_base = &tag;
vec[0].iov_len = sizeof(tag);
vec[1].iov_base = &type;
vec[1].iov_len = sizeof(type);
vec[2].iov_base = &len;
vec[2].iov_len = sizeof(len);
vec[3].iov_base = (void*)payload;
vec[3].iov_len = len;
return write_to_log(LOG_ID_EVENTS, vec, 4);
}
/*
* Like __android_log_security_bwrite, but used for writing strings to the
* security log.
*/
LIBLOG_ABI_PUBLIC int __android_log_security_bswrite(int32_t tag,
const char *payload)
{
struct iovec vec[4];
char type = EVENT_TYPE_STRING;
uint32_t len = strlen(payload);
vec[0].iov_base = &tag;
vec[0].iov_len = sizeof(tag);
vec[1].iov_base = &type;
vec[1].iov_len = sizeof(type);
vec[2].iov_base = &len;
vec[2].iov_len = sizeof(len);
vec[3].iov_base = (void*)payload;
vec[3].iov_len = len;
return write_to_log(LOG_ID_SECURITY, vec, 4);
}
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