Fix Linux lldb local and remote debugging to respect the flag to disable ASLR.

[tfiala]

Summary

This change addresses the following bug:
http://llvm.org/bugs/show_bug.cgi?id=20658.

Ed Maste - please have a look at the (no-op) change to FreeBSD ProcessMonitor. I changed the interface that TOT local Linux and local FreeBSD debugging share in ProcessMonitor to pass in a const ref to the ProcessLaunchInfo structure when we launch a new process for debugging. (I did not build it on FreeBSD - my VM is not reachable on the weekend - but I did tweak the FreeBSD ProcessMonitor to accept the new arg).

I'll do a follow-up patch to add an --enable-aslr flag. Since everything does disable ASLR by default (the flag is always set), I'm not actually finding a way to enable ASLR with the current command setup. (--disable-aslr=False/false/0/no don't work as --disable-aslr isn't expected to take an argument). The net result is instead of always having ASLR stay in the default state, it will now always be disabled on Linux until I make that follow-up change AFAICT.

[tfiala]

This change also adds the Plugins/Process/FreeBSD files to the Xcode project.

[chandlerc]

Looks good to me.

source/Plugins/Process/Linux/NativeProcessLinux.cpp

96–98

The comment here doesn't make much sense in a file which unconditionally #includes <linux/unistd.h> and <sys/personality.h>. This file can only be compiled on a Linux host or with a Linux SDK kicking around.

I think you can just use the enums from <sys/personality.h>. They aren't weird or surprising even if their documentation is limited.

[tfiala]

The defined flags were meant to prevent issues we've hit when
cross-compiling for ARM simulators where the cross-compilers occasionally
are missing some values. But I didn't actually hit that so fair enough, I
can remove it until we know it's an issue.

I just need a buddy build on FreeBSD (or I can watch their buildbot).

[chandlerc]

Personally, I would just watch the build bots. Their entire purpose is to
expose problems on other hosts.

[emaste]

Looks fine, and now that we have a FreeBSD bot on the official buildmaster it's easy to keep top of the results.

lldb.xcodeproj/project.pbxproj

955

Thanks Todd - I'm playing around with the Xcode build now and just noticed this today.

[tfiala]

Ok cool, I'll get this in after removing the dupe of the system flag.

[tfiala]

Thanks Todd - I'm playing around with the Xcode build now and just noticed this today.

My pleasure, Ed!

[tfiala]

Closed by this commit:

svn commit
Sending lldb.xcodeproj/project.pbxproj
Sending source/Plugins/Process/FreeBSD/ProcessMonitor.cpp
Sending source/Plugins/Process/FreeBSD/ProcessMonitor.h
Sending source/Plugins/Process/Linux/NativeProcessLinux.cpp
Sending source/Plugins/Process/Linux/NativeProcessLinux.h
Sending source/Plugins/Process/Linux/ProcessMonitor.cpp
Sending source/Plugins/Process/Linux/ProcessMonitor.h
Sending source/Plugins/Process/POSIX/ProcessPOSIX.cpp
Transmitting file data ........
Committed revision 215822.

lldb.xcodeproj/project.pbxproj

     236124A31986B4E2004EFC37 /* Socket.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = Socket.cpp; sourceTree = "<group>"; };
     236124A61986B50E004EFC37 /* IoObject.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = IoObject.h; path = include/lldb/Host/IoObject.h; sourceTree = "<group>"; };
     236124A71986B50E004EFC37 /* Socket.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = Socket.h; path = include/lldb/Host/Socket.h; sourceTree = "<group>"; };
+    23AB052D199FF639003B8084 /* FreeBSDThread.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = FreeBSDThread.cpp; sourceTree = "<group>"; };
+    23AB052E199FF639003B8084 /* FreeBSDThread.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = FreeBSDThread.h; sourceTree = "<group>"; };
+    23AB052F199FF639003B8084 /* ProcessFreeBSD.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = ProcessFreeBSD.cpp; sourceTree = "<group>"; };
+    23AB0530199FF639003B8084 /* ProcessFreeBSD.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = ProcessFreeBSD.h; sourceTree = "<group>"; };
+    23AB0531199FF639003B8084 /* ProcessMonitor.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = ProcessMonitor.cpp; sourceTree = "<group>"; };
+    23AB0532199FF639003B8084 /* ProcessMonitor.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = ProcessMonitor.h; sourceTree = "<group>"; };
     23DDF224196C3EE600BB8417 /* CommandOptionValidators.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = CommandOptionValidators.cpp; path = source/Interpreter/CommandOptionValidators.cpp; sourceTree = "<group>"; };
     23EDE3301926839700F6A132 /* NativeRegisterContext.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; name = NativeRegisterContext.cpp; path = source/Target/NativeRegisterContext.cpp; sourceTree = "<group>"; };
     23EDE3311926843600F6A132 /* NativeRegisterContext.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = NativeRegisterContext.h; path = include/lldb/Target/NativeRegisterContext.h; sourceTree = "<group>"; };

       path = source/Host/linux;
       sourceTree = "<group>";
     };
+    23AB0526199FF5D3003B8084 /* FreeBSD */ = {
+      isa = PBXGroup;
+      children = (
+        23AB052E199FF639003B8084 /* FreeBSDThread.h */,
+        23AB052D199FF639003B8084 /* FreeBSDThread.cpp */,
+        23AB0530199FF639003B8084 /* ProcessFreeBSD.h */,
+        23AB052F199FF639003B8084 /* ProcessFreeBSD.cpp */,
+        23AB0532199FF639003B8084 /* ProcessMonitor.h */,
+        23AB0531199FF639003B8084 /* ProcessMonitor.cpp */,
+      );
+      path = FreeBSD;
+      sourceTree = "<group>";
+    };
     260C897110F57C5600BB2B04 /* Plugins */ = {
       isa = PBXGroup;
       children = (

       isa = PBXGroup;
       children = (
         26BC179F18C7F4CB00D2196D /* elf-core */,
+        23AB0526199FF5D3003B8084 /* FreeBSD */,
         4CEE62F71145F1C70064CF93 /* GDB Remote */,
         233B008B196106E90090E598 /* Linux */,
         2642FBA713D003B400ED6808 /* MacOSX-Kernel */,

source/Plugins/Process/FreeBSD/ProcessMonitor.h

                    const char *stdout_path,
                    const char *stderr_path,
                    const char *working_dir,
+                   const lldb_private::ProcessLaunchInfo &launch_info,
                    lldb_private::Error &error);
 
     ProcessMonitor(ProcessPOSIX *process,

source/Plugins/Process/FreeBSD/ProcessMonitor.cpp

                                const char *stdout_path,
                                const char *stderr_path,
                                const char *working_dir,
+                               const lldb_private::ProcessLaunchInfo & /* launch_info */,
                                lldb_private::Error &error)
     : m_process(static_cast<ProcessFreeBSD *>(process)),
       m_operation_thread(LLDB_INVALID_HOST_THREAD),

source/Plugins/Process/Linux/NativeProcessLinux.h

                     const char *stdin_path,
                     const char *stdout_path,
                     const char *stderr_path,
-                    const char *working_dir);
+                    const char *working_dir,
+                    const lldb_private::ProcessLaunchInfo &launch_info);
 
             ~LaunchArgs();
 

             const char *m_stdout_path;      // Redirect stdout or NULL.
             const char *m_stderr_path;      // Redirect stderr or NULL.
             const char *m_working_dir;      // Working directory or NULL.
+            const lldb_private::ProcessLaunchInfo &m_launch_info;
         };
 
         struct AttachArgs : OperationArgs

             const char *stdout_path,
             const char *stderr_path,
             const char *working_dir,
+            const lldb_private::ProcessLaunchInfo &launch_info,
             Error &error);
 
         /// Attaches to an existing process.  Forms the

source/Plugins/Process/Linux/NativeProcessLinux.cpp

 #include <stdint.h>
 #include <unistd.h>
 #include <linux/unistd.h>
+#include <sys/personality.h>
 #include <sys/ptrace.h>
 #include <sys/socket.h>
 #include <sys/syscall.h>

   #define ARCH_GET_GS 0x1004
 #endif
 
+// Define personality-related custom flag here so cross compilers and others always have the flag.
+#define LLDB_PERSONALITY_ADDR_NO_RANDOMIZE     0x00040000
+#define LLDB_PERSONALITY_GET_CURRENT_SETTINGS  0xffffffff
 
 // Support hardware breakpoints in case it has not been defined
 #ifndef TRAP_HWBKPT

                                        const char *stdin_path,
                                        const char *stdout_path,
                                        const char *stderr_path,
-                                       const char *working_dir)
+                                       const char *working_dir,
+                                       const lldb_private::ProcessLaunchInfo &launch_info)
     : OperationArgs(monitor),
       m_module(module),
       m_argv(argv),

       m_stdin_path(stdin_path),
       m_stdout_path(stdout_path),
       m_stderr_path(stderr_path),
-      m_working_dir(working_dir) { }
+      m_working_dir(working_dir),
+      m_launch_info(launch_info)
+{
+}
 
 NativeProcessLinux::LaunchArgs::~LaunchArgs()
 { }

             stdout_path,
             stderr_path,
             working_dir,
+            launch_info,
             error);
 
     if (error.Fail ())

     const char *stdout_path,
     const char *stderr_path,
     const char *working_dir,
+    const lldb_private::ProcessLaunchInfo &launch_info,
     lldb_private::Error &error)
 {
     if (module)

         new LaunchArgs(
             this, module, argv, envp,
             stdin_path, stdout_path, stderr_path,
-            working_dir));
+            working_dir, launch_info));
 
     sem_init(&m_operation_pending, 0, 0);
     sem_init(&m_operation_done, 0, 0);

 bool
 NativeProcessLinux::Launch(LaunchArgs *args)
 {
+    assert (args && "null args");
+    if (!args)
+        return false;
+
     NativeProcessLinux *monitor = args->m_monitor;
     assert (monitor && "monitor is NULL");
     if (!monitor)

           if (0 != ::chdir(working_dir))
               exit(eChdirFailed);
 
+        // Disable ASLR if requested.
+        if (args->m_launch_info.GetFlags ().Test (lldb::eLaunchFlagDisableASLR))
+        {
+            const int old_personality = personality (LLDB_PERSONALITY_GET_CURRENT_SETTINGS);
+            if (old_personality == -1)
+            {
+                if (log)
+                    log->Printf ("NativeProcessLinux::%s retrieval of Linux personality () failed: %s. Cannot disable ASLR.", __FUNCTION__, strerror (errno));
+            }
+            else
+            {
+                const int new_personality = personality (LLDB_PERSONALITY_ADDR_NO_RANDOMIZE | old_personality);
+                if (new_personality == -1)
+                {
+                    if (log)
+                        log->Printf ("NativeProcessLinux::%s setting of Linux personality () to disable ASLR failed, ignoring: %s", __FUNCTION__, strerror (errno));
+
+                }
+                else
+                {
+                    if (log)
+                        log->Printf ("NativeProcessLinux::%s disbling ASLR: SUCCESS", __FUNCTION__);
+
+                }
+            }
+        }
+
         // Execute.  We should never return.
         execve(argv[0],
                const_cast<char *const *>(argv),

source/Plugins/Process/Linux/ProcessMonitor.h

                    const char *stdout_path,
                    const char *stderr_path,
                    const char *working_dir,
+                   const lldb_private::ProcessLaunchInfo &launch_info,
                    lldb_private::Error &error);
 
     ProcessMonitor(ProcessPOSIX *process,

                    const char *stdin_path,
                    const char *stdout_path,
                    const char *stderr_path,
-                   const char *working_dir);
+                   const char *working_dir,
+                   const lldb_private::ProcessLaunchInfo &launch_info);
 
         ~LaunchArgs();
 

         const char *m_stdout_path;      // Redirect stdout or NULL.
         const char *m_stderr_path;      // Redirect stderr or NULL.
         const char *m_working_dir;      // Working directory or NULL.
+        const lldb_private::ProcessLaunchInfo &m_launch_info;
     };
 
     void

source/Plugins/Process/Linux/ProcessMonitor.cpp

 #include <string.h>
 #include <stdint.h>
 #include <unistd.h>
+#include <sys/personality.h>
 #include <sys/ptrace.h>
 #include <sys/socket.h>
 #include <sys/syscall.h>

   #define ARCH_GET_GS 0x1004
 #endif
 
+// Define personality-related custom flag here so cross compilers and others always have the flag.
+#define LLDB_PERSONALITY_ADDR_NO_RANDOMIZE     0x00040000
+#define LLDB_PERSONALITY_GET_CURRENT_SETTINGS  0xffffffff
 
 // Support hardware breakpoints in case it has not been defined
 #ifndef TRAP_HWBKPT

                                        const char *stdin_path,
                                        const char *stdout_path,
                                        const char *stderr_path,
-                                       const char *working_dir)
+                                       const char *working_dir,
+                                       const lldb_private::ProcessLaunchInfo &launch_info)
     : OperationArgs(monitor),
       m_module(module),
       m_argv(argv),

       m_stdin_path(stdin_path),
       m_stdout_path(stdout_path),
       m_stderr_path(stderr_path),
-      m_working_dir(working_dir) { }
+      m_working_dir(working_dir),
+      m_launch_info(launch_info)
+{
+}
 
 ProcessMonitor::LaunchArgs::~LaunchArgs()
 { }

                                const char *stdout_path,
                                const char *stderr_path,
                                const char *working_dir,
+                               const lldb_private::ProcessLaunchInfo &launch_info,
                                lldb_private::Error &error)
     : m_process(static_cast<ProcessLinux *>(process)),
       m_operation_thread(LLDB_INVALID_HOST_THREAD),

 {
     std::unique_ptr<LaunchArgs> args(new LaunchArgs(this, module, argv, envp,
                                      stdin_path, stdout_path, stderr_path,
-                                     working_dir));
+                                     working_dir, launch_info));
 
     sem_init(&m_operation_pending, 0, 0);
     sem_init(&m_operation_done, 0, 0);

 bool
 ProcessMonitor::Launch(LaunchArgs *args)
 {
+    assert (args && "null args");
+    if (!args)
+        return false;
+
     ProcessMonitor *monitor = args->m_monitor;
     ProcessLinux &process = monitor->GetProcess();
     const char **argv = args->m_argv;

           if (0 != ::chdir(working_dir))
               exit(eChdirFailed);
 
+        // Disable ASLR if requested.
+        if (args->m_launch_info.GetFlags ().Test (lldb::eLaunchFlagDisableASLR))
+        {
+            const int old_personality = personality (LLDB_PERSONALITY_GET_CURRENT_SETTINGS);
+            if (old_personality == -1)
+            {
+                if (log)
+                    log->Printf ("ProcessMonitor::%s retrieval of Linux personality () failed: %s. Cannot disable ASLR.", __FUNCTION__, strerror (errno));
+            }
+            else
+            {
+                const int new_personality = personality (LLDB_PERSONALITY_ADDR_NO_RANDOMIZE | old_personality);
+                if (new_personality == -1)
+                {
+                    if (log)
+                        log->Printf ("ProcessMonitor::%s setting of Linux personality () to disable ASLR failed, ignoring: %s", __FUNCTION__, strerror (errno));
+
+                }
+                else
+                {
+                    if (log)
+                        log->Printf ("ProcessMonitor::%s disbling ASLR: SUCCESS", __FUNCTION__);
+
+                }
+            }
+        }
+
         // Execute.  We should never return.
         execve(argv[0],
                const_cast<char *const *>(argv),

source/Plugins/Process/POSIX/ProcessPOSIX.cpp

                                     stdout_path, 
                                     stderr_path,
                                     working_dir,
+                                    launch_info,
                                     error);
 
     m_module = module;