Revert "logd: validate and fill in socket credentials"

We don't want to fake socket credentials if they were not provided by
the kernel.  If there is a bug preventing us from reading the
credentials then it must be solved directly.

Test: logd, liblog unit tests
Test: boot and ensure overflow uid doesn't show up

This reverts commit c4e4823b00.

Change-Id: I683129a8a214637635f163ae25c39bb8a47cd50f

logd/LogBuffer.h

@@ -159,12 +159,7 @@ class LogBuffer : public LogBufferInterface {
     const char* pidToName(pid_t pid) {
         return stats.pidToName(pid);
     }
-    virtual uid_t pidToUid(pid_t pid) override {
-        return stats.pidToUid(pid);
-    }
-    virtual pid_t tidToPid(pid_t tid) override {
-        return stats.tidToPid(tid);
-    }
+    uid_t pidToUid(pid_t pid) { return stats.pidToUid(pid); }
     const char* uidToName(uid_t uid) {
         return stats.uidToName(uid);
     }

logd/LogBufferInterface.cpp

@@ -15,15 +15,7 @@
  */
 
 #include "LogBufferInterface.h"
-#include "LogUtils.h"
 
 LogBufferInterface::LogBufferInterface() {
 }
-LogBufferInterface::~LogBufferInterface() {
-}
-uid_t LogBufferInterface::pidToUid(pid_t pid) {
-    return android::pidToUid(pid);
-}
-pid_t LogBufferInterface::tidToPid(pid_t tid) {
-    return android::tidToPid(tid);
-}
+LogBufferInterface::~LogBufferInterface() {}

logd/LogBufferInterface.h

@@ -33,9 +33,6 @@ class LogBufferInterface {
     virtual int log(log_id_t log_id, log_time realtime, uid_t uid, pid_t pid,
                     pid_t tid, const char* msg, uint16_t len) = 0;
 
-    virtual uid_t pidToUid(pid_t pid);
-    virtual pid_t tidToPid(pid_t tid);
-
    private:
     DISALLOW_COPY_AND_ASSIGN(LogBufferInterface);
 };

logd/LogListener.cpp

@@ -14,9 +14,7 @@
  * limitations under the License.
  */
 
-#include <ctype.h>
 #include <limits.h>
-#include <stdio.h>
 #include <sys/cdefs.h>
 #include <sys/prctl.h>
 #include <sys/socket.h>
@@ -78,11 +76,8 @@ bool LogListener::onDataAvailable(SocketClient* cli) {
         cmsg = CMSG_NXTHDR(&hdr, cmsg);
     }
 
-    struct ucred fake_cred;
     if (cred == nullptr) {
-        cred = &fake_cred;
-        cred->pid = 0;
-        cred->uid = DEFAULT_OVERFLOWUID;
+        return false;
     }
 
     if (cred->uid == AID_LOGD) {
@@ -106,27 +101,6 @@ bool LogListener::onDataAvailable(SocketClient* cli) {
         return false;
     }
 
-    // Check credential validity, acquire corrected details if not supplied.
-    if (cred->pid == 0) {
-        cred->pid = logbuf ? logbuf->tidToPid(header->tid)
-                           : android::tidToPid(header->tid);
-        if (cred->pid == getpid()) {
-            // We expect that /proc/<tid>/ is accessible to self even without
-            // readproc group, so that we will always drop messages that come
-            // from any of our logd threads and their library calls.
-            return false;  // ignore self
-        }
-    }
-    if (cred->uid == DEFAULT_OVERFLOWUID) {
-        uid_t uid =
-            logbuf ? logbuf->pidToUid(cred->pid) : android::pidToUid(cred->pid);
-        if (uid == AID_LOGD) {
-            uid = logbuf ? logbuf->pidToUid(header->tid)
-                         : android::pidToUid(cred->pid);
-        }
-        if (uid != AID_LOGD) cred->uid = uid;
-    }
-
     char* msg = ((char*)buffer) + sizeof(android_log_header_t);
     n -= sizeof(android_log_header_t);
 

logd/LogListener.h

@@ -20,16 +20,6 @@
 #include <sysutils/SocketListener.h>
 #include "LogReader.h"
 
-// DEFAULT_OVERFLOWUID is defined in linux/highuid.h, which is not part of
-// the uapi headers for userspace to use.  This value is filled in on the
-// out-of-band socket credentials if the OS fails to find one available.
-// One of the causes of this is if SO_PASSCRED is set, all the packets before
-// that point will have this value.  We also use it in a fake credential if
-// no socket credentials are supplied.
-#ifndef DEFAULT_OVERFLOWUID
-#define DEFAULT_OVERFLOWUID 65534
-#endif
-
 class LogListener : public SocketListener {
     LogBufferInterface* logbuf;
     LogReader* reader;

logd/LogStatistics.cpp

@@ -837,35 +837,12 @@ uid_t pidToUid(pid_t pid) {
     }
     return AID_LOGD;  // associate this with the logger
 }
-
-pid_t tidToPid(pid_t tid) {
-    char buffer[512];
-    snprintf(buffer, sizeof(buffer), "/proc/%u/status", tid);
-    FILE* fp = fopen(buffer, "r");
-    if (fp) {
-        while (fgets(buffer, sizeof(buffer), fp)) {
-            int pid = tid;
-            char space = 0;
-            if ((sscanf(buffer, "Tgid: %d%c", &pid, &space) == 2) &&
-                isspace(space)) {
-                fclose(fp);
-                return pid;
-            }
-        }
-        fclose(fp);
-    }
-    return tid;
-}
 }
 
 uid_t LogStatistics::pidToUid(pid_t pid) {
     return pidTable.add(pid)->second.getUid();
 }
 
-pid_t LogStatistics::tidToPid(pid_t tid) {
-    return tidTable.add(tid)->second.getPid();
-}
-
 // caller must free character string
 const char* LogStatistics::pidToName(pid_t pid) const {
     // An inconvenient truth ... getName() can alter the object

logd/LogStatistics.h

@@ -306,6 +306,10 @@ struct UidEntry : public EntryBaseDropped {
     std::string format(const LogStatistics& stat, log_id_t id) const;
 };
 
+namespace android {
+uid_t pidToUid(pid_t pid);
+}
+
 struct PidEntry : public EntryBaseDropped {
     const pid_t pid;
     uid_t uid;
@@ -385,13 +389,6 @@ struct TidEntry : public EntryBaseDropped {
           uid(android::pidToUid(tid)),
           name(android::tidToName(tid)) {
     }
-    TidEntry(pid_t tid)
-        : EntryBaseDropped(),
-          tid(tid),
-          pid(android::tidToPid(tid)),
-          uid(android::pidToUid(tid)),
-          name(android::tidToName(tid)) {
-    }
     explicit TidEntry(const LogBufferElement* element)
         : EntryBaseDropped(element),
           tid(element->getTid()),
@@ -787,7 +784,6 @@ class LogStatistics {
     // helper (must be locked directly or implicitly by mLogElementsLock)
     const char* pidToName(pid_t pid) const;
     uid_t pidToUid(pid_t pid);
-    pid_t tidToPid(pid_t tid);
     const char* uidToName(uid_t uid) const;
 };
 

logd/LogUtils.h

@@ -38,8 +38,6 @@ size_t sizesTotal();
 // Caller must own and free returned value
 char* pidToName(pid_t pid);
 char* tidToName(pid_t tid);
-uid_t pidToUid(pid_t pid);
-pid_t tidToPid(pid_t tid);
 
 // Furnished in LogTags.cpp. Thread safe.
 const char* tagToName(uint32_t tag);