Changeset 273240 in webkit

Timestamp:

Feb 22, 2021 4:27:44 AM (3 years ago)

Author:

Philippe Normand

Message:

[Flatpak SDK] gdb unusable in sandbox
​https://bugs.webkit.org/show_bug.cgi?id=222247

Reviewed by Žan Doberšek.

This patch adds support for unix signals disabling in developer builds, for the Flatpak SDK
runtime. Currently SIGINT, SIGHUP and SIGTERM will be ignored by the flatpak and bwrap
processes when they're running gdb in the sandbox runtime. This allows for nicer interactive
debugging sessions where Ctrl-C is actually handled by gdb.

• PlatformGTK.cmake:
• PlatformWPE.cmake:
• flatpak/CMakeLists.txt: Added.
• flatpak/flatpakutils.py:

(nullcontext):
(disable_signals):
(WebkitFlatpak.execute_command):
(WebkitFlatpak.run_in_sandbox):

• flatpak/sigaction-disabler.c: Added.

(real_sigaction):
(sigaction):

• flatpak/webkit-bwrap:

Location:

trunk/Tools

Files:

• ChangeLog (modified) (1 diff)
• PlatformGTK.cmake (modified) (1 diff)
• PlatformWPE.cmake (modified) (1 diff)
• flatpak/CMakeLists.txt (added)
• flatpak/flatpakutils.py (modified) (5 diffs)
• flatpak/sigaction-disabler.c (added)
• flatpak/webkit-bwrap (modified) (1 diff)

trunk/Tools/ChangeLog

@@ +1 @@
+2021-02-22  Philippe Normand  <pnormand@igalia.com>
+
+        [Flatpak SDK] gdb unusable in sandbox
+        https://bugs.webkit.org/show_bug.cgi?id=222247
+
+        Reviewed by Žan Doberšek.
+
+        This patch adds support for unix signals disabling in developer builds, for the Flatpak SDK
+        runtime. Currently SIGINT, SIGHUP and SIGTERM will be ignored by the flatpak and bwrap
+        processes when they're running gdb in the sandbox runtime. This allows for nicer interactive
+        debugging sessions where Ctrl-C is actually handled by gdb.
+
+        * PlatformGTK.cmake:
+        * PlatformWPE.cmake:
+        * flatpak/CMakeLists.txt: Added.
+        * flatpak/flatpakutils.py:
+        (nullcontext):
+        (disable_signals):
+        (WebkitFlatpak.execute_command):
+        (WebkitFlatpak.run_in_sandbox):
+        * flatpak/sigaction-disabler.c: Added.
+        (real_sigaction):
+        (sigaction):
+        * flatpak/webkit-bwrap:
+
 2021-02-22  Philippe Normand  <pnormand@igalia.com>
 

trunk/Tools/PlatformGTK.cmake

@@ -3 +3 @@
     add_subdirectory(WebKitTestRunner)
     add_subdirectory(ImageDiff)
+    add_subdirectory(flatpak)
 
     if (ENABLE_API_TESTS)

trunk/Tools/PlatformWPE.cmake

@@ -7 +7 @@
     add_subdirectory(TestRunnerShared)
     add_subdirectory(WebKitTestRunner)
+    add_subdirectory(flatpak)
 
     if (ENABLE_API_TESTS)

trunk/Tools/flatpak/flatpakutils.py

@@ -51 +51 @@
     from urllib2 import urlopen
 
+try:
+    from contextlib import nullcontext
+except ImportError:
+    @contextmanager
+    def nullcontext(enter_result=None):
+        yield enter_result
+
 FLATPAK_REQUIRED_VERSION = "1.4.4"
 
@@ -390 +397 @@
 
 @contextmanager
-def disable_signals(signals=[signal.SIGINT]):
+def disable_signals(signals=[signal.SIGINT, signal.SIGTERM, signal.SIGHUP]):
     old_signal_handlers = []
 
     for disabled_signal in signals:
-        old_signal_handlers.append((disabled_signal, signal.getsignal(disabled_signal)))
+        handler = signal.getsignal(disabled_signal)
+        if handler:
+            old_signal_handlers.append((disabled_signal, handler))
         signal.signal(disabled_signal, signal.SIG_IGN)
 
@@ -518 +527 @@
         self.sccache_scheduler = DEFAULT_SCCACHE_SCHEDULER
 
-    def execute_command(self, args, stdout=None, stderr=None, env=None):
+    def execute_command(self, args, stdout=None, stderr=None, env=None, keep_signals=True):
+        if keep_signals:
+            ctx_manager = nullcontext()
+        else:
+            ctx_manager = disable_signals()
         _log.debug('Running: %s\n' % ' '.join(string_utils.decode(arg) for arg in args))
         result = 0
-        try:
-            result = subprocess.check_call(args, stdout=stdout, stderr=stderr, env=env)
-        except subprocess.CalledProcessError as err:
-            if self.verbose:
-                cmd = ' '.join(string_utils.decode(arg) for arg in err.cmd)
-                message = "'%s' returned a non-zero exit code." % cmd
-                if stderr:
-                    with open(stderr.name, 'r') as stderrf:
-                        message += " Stderr: %s" % stderrf.read()
-                Console.error_message(message)
-            return err.returncode
+        with ctx_manager:
+            try:
+                result = subprocess.check_call(args, stdout=stdout, stderr=stderr, env=env)
+            except subprocess.CalledProcessError as err:
+                if self.verbose:
+                    cmd = ' '.join(string_utils.decode(arg) for arg in err.cmd)
+                    message = "'%s' returned a non-zero exit code." % cmd
+                    if stderr:
+                        with open(stderr.name, 'r') as stderrf:
+                            message += " Stderr: %s" % stderrf.read()
+                    Console.error_message(message)
+                return err.returncode
         return result
 
@@ -884 +898 @@
         flatpak_env["LANG"] = "en_US.UTF-8"
 
+        keep_signals = args[0] != "gdb"
+        if not keep_signals:
+            module_path = os.path.join(self.build_path, "lib", "libsigaction-disabler.so")
+            # Enable module in bwrap child processes.
+            extra_flatpak_args.append("--env=WEBKIT_FLATPAK_LD_PRELOAD=%s" % module_path)
+            # Enable module in `flatpak run`.
+            flatpak_env["LD_PRELOAD"] = module_path
+
         flatpak_command += extra_flatpak_args + ['--command=%s' % args[0], "org.webkit.Sdk"] + args[1:]
 
@@ -897 +919 @@
 
         try:
-            return self.execute_command(flatpak_command, stdout=stdout, env=flatpak_env)
+            return self.execute_command(flatpak_command, stdout=stdout, env=flatpak_env, keep_signals=keep_signals)
         except KeyboardInterrupt:
             return 0

trunk/Tools/flatpak/webkit-bwrap

@@ -111 +111 @@
     bwrap_args.extend(("--setenv", "PATH", "/usr/bin:/usr/lib/sdk/rust-stable/bin/"))
 
+    if environ.get("WEBKIT_FLATPAK_LD_PRELOAD"):
+        os.environ["LD_PRELOAD"] = environ["WEBKIT_FLATPAK_LD_PRELOAD"]
+
     command_line = ' '.join(map(shlex.quote, itertools.chain(bwrap_args, args)))