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platform_system_core/liblog/pmsg_reader.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 <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <private/android_filesystem_config.h>
#include <private/android_logger.h>
#include "config_read.h"
#include "logger.h"
static int pmsgAvailable(log_id_t logId);
static int pmsgVersion(struct android_log_logger* logger,
struct android_log_transport_context* transp);
static int pmsgRead(struct android_log_logger_list* logger_list,
struct android_log_transport_context* transp,
struct log_msg* log_msg);
static void pmsgClose(struct android_log_logger_list* logger_list,
struct android_log_transport_context* transp);
static int pmsgClear(struct android_log_logger* logger,
struct android_log_transport_context* transp);
LIBLOG_HIDDEN struct android_log_transport_read pmsgLoggerRead = {
.node = { &pmsgLoggerRead.node, &pmsgLoggerRead.node },
.name = "pmsg",
.available = pmsgAvailable,
.version = pmsgVersion,
.read = pmsgRead,
.poll = NULL,
.close = pmsgClose,
.clear = pmsgClear,
.setSize = NULL,
.getSize = NULL,
.getReadableSize = NULL,
.getPrune = NULL,
.setPrune = NULL,
.getStats = NULL,
};
static int pmsgAvailable(log_id_t logId) {
if (logId > LOG_ID_SECURITY) {
return -EINVAL;
}
if (access("/dev/pmsg0", W_OK) == 0) {
return 0;
}
return -EBADF;
}
/* Determine the credentials of the caller */
static bool uid_has_log_permission(uid_t uid) {
return (uid == AID_SYSTEM) || (uid == AID_LOG) || (uid == AID_ROOT) ||
(uid == AID_LOGD);
}
static uid_t get_best_effective_uid() {
uid_t euid;
uid_t uid;
gid_t gid;
ssize_t i;
static uid_t last_uid = (uid_t)-1;
if (last_uid != (uid_t)-1) {
return last_uid;
}
uid = __android_log_uid();
if (uid_has_log_permission(uid)) {
return last_uid = uid;
}
euid = geteuid();
if (uid_has_log_permission(euid)) {
return last_uid = euid;
}
gid = getgid();
if (uid_has_log_permission(gid)) {
return last_uid = gid;
}
gid = getegid();
if (uid_has_log_permission(gid)) {
return last_uid = gid;
}
i = getgroups((size_t)0, NULL);
if (i > 0) {
gid_t list[i];
getgroups(i, list);
while (--i >= 0) {
if (uid_has_log_permission(list[i])) {
return last_uid = list[i];
}
}
}
return last_uid = uid;
}
static int pmsgClear(struct android_log_logger* logger __unused,
struct android_log_transport_context* transp __unused) {
if (uid_has_log_permission(get_best_effective_uid())) {
return unlink("/sys/fs/pstore/pmsg-ramoops-0");
}
errno = EPERM;
return -1;
}
/*
* returns the logger version
*/
static int pmsgVersion(struct android_log_logger* logger __unused,
struct android_log_transport_context* transp __unused) {
return 4;
}
static int pmsgRead(struct android_log_logger_list* logger_list,
struct android_log_transport_context* transp,
struct log_msg* log_msg) {
ssize_t ret;
off_t current, next;
uid_t uid;
struct android_log_logger* logger;
struct __attribute__((__packed__)) {
android_pmsg_log_header_t p;
android_log_header_t l;
uint8_t prio;
} buf;
static uint8_t preread_count;
bool is_system;
memset(log_msg, 0, sizeof(*log_msg));
if (atomic_load(&transp->context.fd) <= 0) {
int i, fd = open("/sys/fs/pstore/pmsg-ramoops-0", O_RDONLY | O_CLOEXEC);
if (fd < 0) {
return -errno;
}
if (fd == 0) { /* Argggg */
fd = open("/sys/fs/pstore/pmsg-ramoops-0", O_RDONLY | O_CLOEXEC);
close(0);
if (fd < 0) {
return -errno;
}
}
i = atomic_exchange(&transp->context.fd, fd);
if ((i > 0) && (i != fd)) {
close(i);
}
preread_count = 0;
}
while (1) {
int fd;
if (preread_count < sizeof(buf)) {
fd = atomic_load(&transp->context.fd);
if (fd <= 0) {
return -EBADF;
}
ret = TEMP_FAILURE_RETRY(
read(fd, &buf.p.magic + preread_count, sizeof(buf) - preread_count));
if (ret < 0) {
return -errno;
}
preread_count += ret;
}
if (preread_count != sizeof(buf)) {
return preread_count ? -EIO : -EAGAIN;
}
if ((buf.p.magic != LOGGER_MAGIC) || (buf.p.len <= sizeof(buf)) ||
(buf.p.len > (sizeof(buf) + LOGGER_ENTRY_MAX_PAYLOAD)) ||
(buf.l.id >= LOG_ID_MAX) || (buf.l.realtime.tv_nsec >= NS_PER_SEC) ||
((buf.l.id != LOG_ID_EVENTS) && (buf.l.id != LOG_ID_SECURITY) &&
((buf.prio == ANDROID_LOG_UNKNOWN) ||
(buf.prio == ANDROID_LOG_DEFAULT) ||
(buf.prio >= ANDROID_LOG_SILENT)))) {
do {
memmove(&buf.p.magic, &buf.p.magic + 1, --preread_count);
} while (preread_count && (buf.p.magic != LOGGER_MAGIC));
continue;
}
preread_count = 0;
if ((transp->logMask & (1 << buf.l.id)) &&
((!logger_list->start.tv_sec && !logger_list->start.tv_nsec) ||
((logger_list->start.tv_sec <= buf.l.realtime.tv_sec) &&
((logger_list->start.tv_sec != buf.l.realtime.tv_sec) ||
(logger_list->start.tv_nsec <= buf.l.realtime.tv_nsec)))) &&
(!logger_list->pid || (logger_list->pid == buf.p.pid))) {
uid = get_best_effective_uid();
is_system = uid_has_log_permission(uid);
if (is_system || (uid == buf.p.uid)) {
char* msg = is_system ? log_msg->entry_v4.msg : log_msg->entry_v3.msg;
*msg = buf.prio;
fd = atomic_load(&transp->context.fd);
if (fd <= 0) {
return -EBADF;
}
ret = TEMP_FAILURE_RETRY(
read(fd, msg + sizeof(buf.prio), buf.p.len - sizeof(buf)));
if (ret < 0) {
return -errno;
}
if (ret != (ssize_t)(buf.p.len - sizeof(buf))) {
return -EIO;
}
log_msg->entry_v4.len = buf.p.len - sizeof(buf) + sizeof(buf.prio);
log_msg->entry_v4.hdr_size =
is_system ? sizeof(log_msg->entry_v4) : sizeof(log_msg->entry_v3);
log_msg->entry_v4.pid = buf.p.pid;
log_msg->entry_v4.tid = buf.l.tid;
log_msg->entry_v4.sec = buf.l.realtime.tv_sec;
log_msg->entry_v4.nsec = buf.l.realtime.tv_nsec;
log_msg->entry_v4.lid = buf.l.id;
if (is_system) {
log_msg->entry_v4.uid = buf.p.uid;
}
return ret + sizeof(buf.prio) + log_msg->entry_v4.hdr_size;
}
}
fd = atomic_load(&transp->context.fd);
if (fd <= 0) {
return -EBADF;
}
current = TEMP_FAILURE_RETRY(lseek(fd, (off_t)0, SEEK_CUR));
if (current < 0) {
return -errno;
}
fd = atomic_load(&transp->context.fd);
if (fd <= 0) {
return -EBADF;
}
next = TEMP_FAILURE_RETRY(
lseek(fd, (off_t)(buf.p.len - sizeof(buf)), SEEK_CUR));
if (next < 0) {
return -errno;
}
if ((next - current) != (ssize_t)(buf.p.len - sizeof(buf))) {
return -EIO;
}
}
}
static void pmsgClose(struct android_log_logger_list* logger_list __unused,
struct android_log_transport_context* transp) {
int fd = atomic_exchange(&transp->context.fd, 0);
if (fd > 0) {
close(fd);
}
}
LIBLOG_ABI_PRIVATE ssize_t
__android_log_pmsg_file_read(log_id_t logId, char prio, const char* prefix,
__android_log_pmsg_file_read_fn fn, void* arg) {
ssize_t ret;
struct android_log_logger_list logger_list;
struct android_log_transport_context transp;
struct content {
struct listnode node;
union {
struct logger_entry_v4 entry;
struct logger_entry_v4 entry_v4;
struct logger_entry_v3 entry_v3;
struct logger_entry_v2 entry_v2;
struct logger_entry entry_v1;
};
} * content;
struct names {
struct listnode node;
struct listnode content;
log_id_t id;
char prio;
char name[];
} * names;
struct listnode name_list;
struct listnode *node, *n;
size_t len, prefix_len;
if (!fn) {
return -EINVAL;
}
/* Add just enough clues in logger_list and transp to make API function */
memset(&logger_list, 0, sizeof(logger_list));
memset(&transp, 0, sizeof(transp));
logger_list.mode =
ANDROID_LOG_PSTORE | ANDROID_LOG_NONBLOCK | ANDROID_LOG_RDONLY;
transp.logMask = (unsigned)-1;
if (logId != LOG_ID_ANY) {
transp.logMask = (1 << logId);
}
transp.logMask &=
~((1 << LOG_ID_KERNEL) | (1 << LOG_ID_EVENTS) | (1 << LOG_ID_SECURITY));
if (!transp.logMask) {
return -EINVAL;
}
/* Initialize name list */
list_init(&name_list);
ret = SSIZE_MAX;
/* Validate incoming prefix, shift until it contains only 0 or 1 : or / */
prefix_len = 0;
if (prefix) {
const char *prev = NULL, *last = NULL, *cp = prefix;
while ((cp = strpbrk(cp, "/:"))) {
prev = last;
last = cp;
cp = cp + 1;
}
if (prev) {
prefix = prev + 1;
}
prefix_len = strlen(prefix);
}
/* Read the file content */
while (pmsgRead(&logger_list, &transp, &transp.logMsg) > 0) {
char* cp;
size_t hdr_size = transp.logMsg.entry.hdr_size
? transp.logMsg.entry.hdr_size
: sizeof(transp.logMsg.entry_v1);
char* msg = (char*)&transp.logMsg + hdr_size;
char* split = NULL;
if ((hdr_size < sizeof(transp.logMsg.entry_v1)) ||
(hdr_size > sizeof(transp.logMsg.entry))) {
continue;
}
/* Check for invalid sequence number */
if ((transp.logMsg.entry.nsec % ANDROID_LOG_PMSG_FILE_SEQUENCE) ||
((transp.logMsg.entry.nsec / ANDROID_LOG_PMSG_FILE_SEQUENCE) >=
ANDROID_LOG_PMSG_FILE_MAX_SEQUENCE)) {
continue;
}
/* Determine if it has <dirbase>:<filebase> format for tag */
len = transp.logMsg.entry.len - sizeof(prio);
for (cp = msg + sizeof(prio); *cp && isprint(*cp) && !isspace(*cp) && --len;
++cp) {
if (*cp == ':') {
if (split) {
break;
}
split = cp;
}
}
if (*cp || !split) {
continue;
}
/* Filters */
if (prefix_len && strncmp(msg + sizeof(prio), prefix, prefix_len)) {
size_t offset;
/*
* Allow : to be a synonym for /
* Things we do dealing with const char * and do not alloc
*/
split = strchr(prefix, ':');
if (split) {
continue;
}
split = strchr(prefix, '/');
if (!split) {
continue;
}
offset = split - prefix;
if ((msg[offset + sizeof(prio)] != ':') ||
strncmp(msg + sizeof(prio), prefix, offset)) {
continue;
}
++offset;
if ((prefix_len > offset) && strncmp(&msg[offset + sizeof(prio)],
split + 1, prefix_len - offset)) {
continue;
}
}
if ((prio != ANDROID_LOG_ANY) && (*msg < prio)) {
continue;
}
/* check if there is an existing entry */
list_for_each(node, &name_list) {
names = node_to_item(node, struct names, node);
if (!strcmp(names->name, msg + sizeof(prio)) &&
(names->id == transp.logMsg.entry.lid) && (names->prio == *msg)) {
break;
}
}
/* We do not have an existing entry, create and add one */
if (node == &name_list) {
static const char numbers[] = "0123456789";
unsigned long long nl;
len = strlen(msg + sizeof(prio)) + 1;
names = calloc(1, sizeof(*names) + len);
if (!names) {
ret = -ENOMEM;
break;
}
strcpy(names->name, msg + sizeof(prio));
names->id = transp.logMsg.entry.lid;
names->prio = *msg;
list_init(&names->content);
/*
* Insert in reverse numeric _then_ alpha sorted order as
* representative of log rotation:
*
* log.10
* klog.10
* . . .
* log.2
* klog.2
* log.1
* klog.1
* log
* klog
*
* thus when we present the content, we are provided the oldest
* first, which when 'refreshed' could spill off the end of the
* pmsg FIFO but retaining the newest data for last with best
* chances to survive.
*/
nl = 0;
cp = strpbrk(names->name, numbers);
if (cp) {
nl = strtoull(cp, NULL, 10);
}
list_for_each_reverse(node, &name_list) {
struct names* a_name = node_to_item(node, struct names, node);
const char* r = a_name->name;
int compare = 0;
unsigned long long nr = 0;
cp = strpbrk(r, numbers);
if (cp) {
nr = strtoull(cp, NULL, 10);
}
if (nr != nl) {
compare = (nl > nr) ? 1 : -1;
}
if (compare == 0) {
compare = strcmp(names->name, r);
}
if (compare <= 0) {
break;
}
}
list_add_head(node, &names->node);
}
/* Remove any file fragments that match our sequence number */
list_for_each_safe(node, n, &names->content) {
content = node_to_item(node, struct content, node);
if (transp.logMsg.entry.nsec == content->entry.nsec) {
list_remove(&content->node);
free(content);
}
}
/* Add content */
content =
calloc(1, sizeof(content->node) + hdr_size + transp.logMsg.entry.len);
if (!content) {
ret = -ENOMEM;
break;
}
memcpy(&content->entry, &transp.logMsg.entry,
hdr_size + transp.logMsg.entry.len);
/* Insert in sequence number sorted order, to ease reconstruction */
list_for_each_reverse(node, &names->content) {
if ((node_to_item(node, struct content, node))->entry.nsec <
transp.logMsg.entry.nsec) {
break;
}
}
list_add_head(node, &content->node);
}
pmsgClose(&logger_list, &transp);
/* Progress through all the collected files */
list_for_each_safe(node, n, &name_list) {
struct listnode *content_node, *m;
char* buf;
size_t sequence, tag_len;
names = node_to_item(node, struct names, node);
/* Construct content into a linear buffer */
buf = NULL;
len = 0;
sequence = 0;
tag_len = strlen(names->name) + sizeof(char); /* tag + nul */
list_for_each_safe(content_node, m, &names->content) {
ssize_t add_len;
content = node_to_item(content_node, struct content, node);
add_len = content->entry.len - tag_len - sizeof(prio);
if (add_len <= 0) {
list_remove(content_node);
free(content);
continue;
}
if (!buf) {
buf = malloc(sizeof(char));
if (!buf) {
ret = -ENOMEM;
list_remove(content_node);
free(content);
continue;
}
*buf = '\0';
}
/* Missing sequence numbers */
while (sequence < content->entry.nsec) {
/* plus space for enforced nul */
buf = realloc(buf, len + sizeof(char) + sizeof(char));
if (!buf) {
break;
}
buf[len] = '\f'; /* Mark missing content with a form feed */
buf[++len] = '\0';
sequence += ANDROID_LOG_PMSG_FILE_SEQUENCE;
}
if (!buf) {
ret = -ENOMEM;
list_remove(content_node);
free(content);
continue;
}
/* plus space for enforced nul */
buf = realloc(buf, len + add_len + sizeof(char));
if (!buf) {
ret = -ENOMEM;
list_remove(content_node);
free(content);
continue;
}
memcpy(buf + len,
(char*)&content->entry + content->entry.hdr_size + tag_len +
sizeof(prio),
add_len);
len += add_len;
buf[len] = '\0'; /* enforce trailing hidden nul */
sequence = content->entry.nsec + ANDROID_LOG_PMSG_FILE_SEQUENCE;
list_remove(content_node);
free(content);
}
if (buf) {
if (len) {
/* Buffer contains enforced trailing nul just beyond length */
ssize_t r;
*strchr(names->name, ':') = '/'; /* Convert back to filename */
r = (*fn)(names->id, names->prio, names->name, buf, len, arg);
if ((ret >= 0) && (r > 0)) {
if (ret == SSIZE_MAX) {
ret = r;
} else {
ret += r;
}
} else if (r < ret) {
ret = r;
}
}
free(buf);
}
list_remove(node);
free(names);
}
return (ret == SSIZE_MAX) ? -ENOENT : ret;
}
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