logd: institute getGroups for socket credentials

Change-Id: Ib8be84d2a3f873e91fb1495df439a498f395c137

logd/CommandListener.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012-2013 The Android Open Source Project
+ * 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.
@@ -24,10 +24,11 @@
 #include <sys/socket.h>
 #include <sys/types.h>
 
-#include <sysutils/SocketClient.h>
 #include <private/android_filesystem_config.h>
+#include <sysutils/SocketClient.h>
 
 #include "CommandListener.h"
+#include "LogCommand.h"
 
 CommandListener::CommandListener(LogBuffer *buf, LogReader * /*reader*/,
                                  LogListener * /*swl*/)
@@ -62,9 +63,7 @@ CommandListener::ClearCmd::ClearCmd(LogBuffer *buf)
 
 int CommandListener::ClearCmd::runCommand(SocketClient *cli,
                                          int argc, char **argv) {
-    if ((cli->getUid() != AID_ROOT)
-            && (cli->getGid() != AID_ROOT)
-            && (cli->getGid() != AID_LOG)) {
+    if (!clientHasLogCredentials(cli)) {
         cli->sendMsg("Permission Denied");
         return 0;
     }
@@ -75,7 +74,7 @@ int CommandListener::ClearCmd::runCommand(SocketClient *cli,
     }
 
     int id = atoi(argv[1]);
-    if ((id < LOG_ID_MIN) || (id >= LOG_ID_MAX)) {
+    if ((id < LOG_ID_MIN) || (LOG_ID_MAX <= id)) {
         cli->sendMsg("Range Error");
         return 0;
     }
@@ -85,7 +84,6 @@ int CommandListener::ClearCmd::runCommand(SocketClient *cli,
     return 0;
 }
 
-
 CommandListener::GetBufSizeCmd::GetBufSizeCmd(LogBuffer *buf)
         : LogCommand("getLogSize")
         , mBuf(*buf)
@@ -99,7 +97,7 @@ int CommandListener::GetBufSizeCmd::runCommand(SocketClient *cli,
     }
 
     int id = atoi(argv[1]);
-    if ((id < LOG_ID_MIN) || (id >= LOG_ID_MAX)) {
+    if ((id < LOG_ID_MIN) || (LOG_ID_MAX <= id)) {
         cli->sendMsg("Range Error");
         return 0;
     }
@@ -124,7 +122,7 @@ int CommandListener::GetBufSizeUsedCmd::runCommand(SocketClient *cli,
     }
 
     int id = atoi(argv[1]);
-    if ((id < LOG_ID_MIN) || (id >= LOG_ID_MAX)) {
+    if ((id < LOG_ID_MIN) || (LOG_ID_MAX <= id)) {
         cli->sendMsg("Range Error");
         return 0;
     }

logd/FlushCommand.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012-2013 The Android Open Source Project
+ * 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.
@@ -15,11 +15,12 @@
  */
 
 #include <stdlib.h>
-#include <private/android_filesystem_config.h>
+
 #include "FlushCommand.h"
 #include "LogBufferElement.h"
-#include "LogTimes.h"
+#include "LogCommand.h"
 #include "LogReader.h"
+#include "LogTimes.h"
 
 FlushCommand::FlushCommand(LogReader &reader,
                            bool nonBlock,
@@ -80,7 +81,5 @@ void FlushCommand::runSocketCommand(SocketClient *client) {
 }
 
 bool FlushCommand::hasReadLogs(SocketClient *client) {
-    return (client->getUid() == AID_ROOT)
-            || (client->getGid() == AID_ROOT)
-            || (client->getGid() == AID_LOG);
+    return clientHasLogCredentials(client);
 }

logd/LogCommand.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012-2013 The Android Open Source Project
+ * 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.
@@ -14,8 +14,117 @@
  * 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_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;
+}

logd/LogCommand.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012-2013 The Android Open Source Project
+ * 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.
@@ -17,6 +17,7 @@
 #ifndef _LOGD_COMMAND_H
 #define _LOGD_COMMAND_H
 
+#include <sysutils/SocketClient.h>
 #include <sysutils/FrameworkCommand.h>
 
 class LogCommand : public FrameworkCommand {
@@ -25,4 +26,6 @@ public:
     virtual ~LogCommand() {}
 };
 
+bool clientHasLogCredentials(SocketClient * cli);
+
 #endif