131 lines
3.8 KiB
C++
131 lines
3.8 KiB
C++
/*
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* Copyright (C) 2012-2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <private/android_filesystem_config.h>
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#include "LogCommand.h"
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LogCommand::LogCommand(const char *cmd) : FrameworkCommand(cmd) {
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}
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// gets a list of supplementary group IDs associated with
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// the socket peer. This is implemented by opening
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// /proc/PID/status and look for the "Group:" line.
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//
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// This function introduces races especially since status
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// can change 'shape' while reading, the net result is err
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// on lack of permission.
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//
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// Race-free alternative is to introduce pairs of sockets
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// and threads for each command and reading, one each that
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// has open permissions, and one that has restricted
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// permissions.
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static bool groupIsLog(char *buf) {
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char *ptr;
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static const char ws[] = " \n";
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bool ret = false;
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for (buf = strtok_r(buf, ws, &ptr); buf; buf = strtok_r(NULL, ws, &ptr)) {
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errno = 0;
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gid_t Gid = strtol(buf, NULL, 10);
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if (errno != 0) {
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return false;
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}
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if (Gid == AID_LOG) {
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ret = true;
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}
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}
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return ret;
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}
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bool clientHasLogCredentials(SocketClient * cli) {
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uid_t uid = cli->getUid();
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if (uid == AID_ROOT) {
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return true;
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}
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gid_t gid = cli->getGid();
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if ((gid == AID_ROOT) || (gid == AID_SYSTEM) || (gid == AID_LOG)) {
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return true;
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}
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// FYI We will typically be here for 'adb logcat'
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bool ret = false;
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char filename[1024];
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snprintf(filename, sizeof(filename), "/proc/%d/status", cli->getPid());
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FILE *file = fopen(filename, "r");
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if (!file) {
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return ret;
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}
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bool foundGid = false;
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bool foundUid = false;
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char line[1024];
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while (fgets(line, sizeof(line), file)) {
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static const char groups_string[] = "Groups:\t";
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static const char uid_string[] = "Uid:\t";
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static const char gid_string[] = "Gid:\t";
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if (strncmp(groups_string, line, strlen(groups_string)) == 0) {
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ret = groupIsLog(line + strlen(groups_string));
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if (!ret) {
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break;
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}
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} else if (strncmp(uid_string, line, strlen(uid_string)) == 0) {
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uid_t u[4] = { (uid_t) -1, (uid_t) -1, (uid_t) -1, (uid_t) -1};
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sscanf(line + strlen(uid_string), "%u\t%u\t%u\t%u",
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&u[0], &u[1], &u[2], &u[3]);
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// Protect against PID reuse by checking that the UID is the same
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if ((uid != u[0]) || (uid != u[1]) || (uid != u[2]) || (uid != u[3])) {
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ret = false;
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break;
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}
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foundUid = true;
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} else if (strncmp(gid_string, line, strlen(gid_string)) == 0) {
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gid_t g[4] = { (gid_t) -1, (gid_t) -1, (gid_t) -1, (gid_t) -1};
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sscanf(line + strlen(gid_string), "%u\t%u\t%u\t%u",
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&g[0], &g[1], &g[2], &g[3]);
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// Protect against PID reuse by checking that the GID is the same
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if ((gid != g[0]) || (gid != g[1]) || (gid != g[2]) || (gid != g[3])) {
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ret = false;
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break;
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}
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foundGid = true;
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}
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}
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fclose(file);
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if (!foundGid || !foundUid) {
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ret = false;
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}
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return ret;
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}
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