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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.
*/
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <private/android_filesystem_config.h>
#include "LogCommand.h"
LogCommand::LogCommand(const char *cmd)
: FrameworkCommand(cmd) {
}
// gets a list of supplementary group IDs associated with
// the socket peer. This is implemented by opening
// /proc/PID/status and look for the "Group:" line.
//
// This function introduces races especially since status
// can change 'shape' while reading, the net result is err
// on lack of permission.
//
// Race-free alternative is to introduce pairs of sockets
// and threads for each command and reading, one each that
// has open permissions, and one that has restricted
// permissions.
static bool groupIsLog(char *buf) {
char *ptr;
static const char ws[] = " \n";
bool ret = false;
for (buf = strtok_r(buf, ws, &ptr); buf; buf = strtok_r(NULL, ws, &ptr)) {
errno = 0;
gid_t Gid = strtol(buf, NULL, 10);
if (errno != 0) {
return false;
}
if (Gid == AID_LOG) {
ret = true;
}
}
return ret;
}
bool clientHasLogCredentials(SocketClient * cli) {
uid_t uid = cli->getUid();
if (uid == AID_ROOT) {
return true;
}
gid_t gid = cli->getGid();
if ((gid == AID_ROOT) || (gid == AID_SYSTEM) || (gid == AID_LOG)) {
return true;
}
// FYI We will typically be here for 'adb logcat'
bool ret = false;
char filename[1024];
snprintf(filename, sizeof(filename), "/proc/%d/status", cli->getPid());
FILE *file = fopen(filename, "r");
if (!file) {
return ret;
}
bool foundGid = false;
bool foundUid = false;
char line[1024];
while (fgets(line, sizeof(line), file)) {
static const char groups_string[] = "Groups:\t";
static const char uid_string[] = "Uid:\t";
static const char gid_string[] = "Gid:\t";
if (strncmp(groups_string, line, strlen(groups_string)) == 0) {
ret = groupIsLog(line + strlen(groups_string));
if (!ret) {
break;
}
} else if (strncmp(uid_string, line, strlen(uid_string)) == 0) {
uid_t u[4] = { (uid_t) -1, (uid_t) -1, (uid_t) -1, (uid_t) -1};
sscanf(line + strlen(uid_string), "%u\t%u\t%u\t%u",
&u[0], &u[1], &u[2], &u[3]);
// Protect against PID reuse by checking that the UID is the same
if ((uid != u[0]) || (uid != u[1]) || (uid != u[2]) || (uid != u[3])) {
ret = false;
break;
}
foundUid = true;
} else if (strncmp(gid_string, line, strlen(gid_string)) == 0) {
gid_t g[4] = { (gid_t) -1, (gid_t) -1, (gid_t) -1, (gid_t) -1};
sscanf(line + strlen(gid_string), "%u\t%u\t%u\t%u",
&g[0], &g[1], &g[2], &g[3]);
// Protect against PID reuse by checking that the GID is the same
if ((gid != g[0]) || (gid != g[1]) || (gid != g[2]) || (gid != g[3])) {
ret = false;
break;
}
foundGid = true;
}
}
fclose(file);
if (!foundGid || !foundUid) {
ret = false;
}
return ret;
}
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