logd: selinux auditd initial commit

Initial commit for an audit daemon that writes kernel audit
messages to the Android logger. The daemon searches dmesg
for all lines that contain "audit" and writes them. Then
receiving the messages from the netlink socket.

It also formats the messages so they are compatable with
ausearch (type=<t> <m> format)

Modified: Mark Salyzyn <[email protected]>

- do not start auditd
- merge into logd, stripping unnecessary file logging.
- Convert headers and code to support C++
- Fix bugs in libaudit
- squash timestamp (replace with 0.0) due to duplication
- squash pid due to duplication
- squash comm due to duplication

Change-Id: I421bcf33e7e670d596628b1b5c7c25536ce2d3fe

logd/Android.mk

@@ -19,7 +19,9 @@ LOCAL_SRC_FILES := \
     LogBufferElement.cpp \
     LogTimes.cpp \
     LogStatistics.cpp \
-    LogWhiteBlackList.cpp
+    LogWhiteBlackList.cpp \
+    libaudit.c \
+    LogAudit.cpp
 
 LOCAL_SHARED_LIBRARIES := \
     libsysutils \

logd/LogAudit.cpp

@@ -0,0 +1,184 @@
+/*
+ * Copyright (C) 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 <ctype.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <sys/klog.h>
+
+#include "libaudit.h"
+#include "LogAudit.h"
+
+LogAudit::LogAudit(LogBuffer *buf, LogReader *reader)
+        : SocketListener(getLogSocket(), false)
+        , logbuf(buf)
+        , reader(reader) {
+    logDmsg();
+}
+
+bool LogAudit::onDataAvailable(SocketClient *cli) {
+    struct audit_message rep;
+
+    if (audit_get_reply(cli->getSocket(), &rep, GET_REPLY_BLOCKING, 0) < 0) {
+        SLOGE("Failed on audit_get_reply with error: %s", strerror(errno));
+        return false;
+    }
+
+    logPrint("type=%d %.*s", rep.nlh.nlmsg_type, rep.nlh.nlmsg_len, rep.data);
+
+    return true;
+}
+
+#define AUDIT_LOG_ID   LOG_ID_MAIN
+#define AUDIT_LOG_PRIO ANDROID_LOG_WARN
+
+int LogAudit::logPrint(const char *fmt, ...) {
+    if (fmt == NULL) {
+        return -EINVAL;
+    }
+
+    va_list args;
+
+    char *str = NULL;
+    va_start(args, fmt);
+    int rc = vasprintf(&str, fmt, args);
+    va_end(args);
+
+    if (rc < 0) {
+        return rc;
+    }
+
+    pid_t pid = getpid();
+    pid_t tid = gettid();
+    uid_t uid = getuid();
+    log_time now;
+
+    static const char audit_str[] = " audit(";
+    char *timeptr = strstr(str, audit_str);
+    char *cp;
+    if (timeptr
+            && ((cp = now.strptime(timeptr + sizeof(audit_str) - 1, "%s.%q")))
+            && (*cp == ':')) {
+        memcpy(timeptr + sizeof(audit_str) - 1, "0.0", 3);
+        strcpy(timeptr + sizeof(audit_str) - 1 + 3, cp);
+    } else {
+        now.strptime("", ""); // side effect of setting CLOCK_REALTIME
+    }
+
+    static const char pid_str[] = " pid=";
+    char *pidptr = strstr(str, pid_str);
+    if (pidptr && isdigit(pidptr[sizeof(pid_str) - 1])) {
+        cp = pidptr + sizeof(pid_str) - 1;
+        pid = 0;
+        while (isdigit(*cp)) {
+            pid = (pid * 10) + (*cp - '0');
+            ++cp;
+        }
+        tid = pid;
+        uid = logbuf->pidToUid(pid);
+        strcpy(pidptr, cp);
+    }
+
+    static const char comm_str[] = " comm=\"";
+    char *comm = strstr(str, comm_str);
+    if (comm) {
+        cp = comm;
+        comm += sizeof(comm_str) - 1;
+        char *ecomm = strchr(comm, '"');
+        if (ecomm) {
+            *ecomm = '\0';
+        }
+        comm = strdup(comm);
+        if (ecomm) {
+            strcpy(cp, ecomm + 1);
+        }
+    } else if (pid == getpid()) {
+        pid = tid;
+        comm = strdup("auditd");
+    } else if (!(comm = logbuf->pidToName(pid))) {
+        comm = strdup("unknown");
+    }
+
+    size_t l = strlen(comm) + 1;
+    size_t n = l + strlen(str) + 2;
+
+    char *newstr = reinterpret_cast<char *>(malloc(n));
+    if (!newstr) {
+        free(comm);
+        free(str);
+        return -ENOMEM;
+    }
+
+    *newstr = AUDIT_LOG_PRIO;
+    strcpy(newstr + 1, comm);
+    free(comm);
+    strcpy(newstr + 1 + l, str);
+    free(str);
+
+    unsigned short len = n; // cap to internal maximum
+    if (len != n) {
+        len = -1;
+    }
+    logbuf->log(AUDIT_LOG_ID, now, uid, pid, tid, newstr, len);
+    reader->notifyNewLog();
+
+    free(newstr);
+
+    return rc;
+}
+
+void LogAudit::logDmsg() {
+    int len = klogctl(KLOG_SIZE_BUFFER, NULL, 0);
+    if (len <= 0) {
+        return;
+    }
+
+    len++;
+    char buf[len];
+
+    int rc = klogctl(KLOG_READ_ALL, buf, len);
+
+    buf[len - 1] = '\0';
+
+    for(char *tok = buf; (rc >= 0) && ((tok = strtok(tok, "\r\n"))); tok = NULL) {
+        char *audit = strstr(tok, " audit(");
+        if (!audit) {
+            continue;
+        }
+
+        *audit++ = '\0';
+
+        char *type = strstr(tok, "type=");
+        if (type) {
+            rc = logPrint("%s %s", type, audit);
+        } else {
+            rc = logPrint("%s", audit);
+        }
+    }
+}
+
+int LogAudit::getLogSocket() {
+    int fd = audit_open();
+    if (fd < 0) {
+        return fd;
+    }
+    if (audit_set_pid(fd, getpid(), WAIT_YES) < 0) {
+        audit_close(fd);
+        fd = -1;
+    }
+    return fd;
+}

logd/LogAudit.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 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.
+ */
+
+#ifndef _LOGD_LOG_AUDIT_H__
+#define _LOGD_LOG_AUDIT_H__
+
+#include <sysutils/SocketListener.h>
+#include "LogReader.h"
+
+class LogAudit : public SocketListener {
+    LogBuffer *logbuf;
+    LogReader *reader;
+
+public:
+    LogAudit(LogBuffer *buf, LogReader *reader);
+
+protected:
+    virtual bool onDataAvailable(SocketClient *cli);
+
+private:
+    static int getLogSocket();
+    void logDmsg();
+    int logPrint(const char *fmt, ...)
+        __attribute__ ((__format__ (__printf__, 2, 3)));
+};
+
+#endif

logd/README.auditd

@@ -0,0 +1,17 @@
+Auditd Daemon
+
+The audit daemon is a simplified version of its desktop
+counterpart designed to gather the audit logs from the
+audit kernel subsystem. The audit subsystem of the kernel
+includes Linux Security Modules (LSM) messages as well.
+
+To enable the audit subsystem, you must add this to your
+kernel config:
+CONFIG_AUDIT=y
+
+To enable a LSM, you must consult that LSM's documentation, the
+example below is for SELinux:
+CONFIG_SECURITY_SELINUX=y
+
+This does not include possible dependencies that may need to be
+satisfied for that particular LSM.