255 lines
8.6 KiB
Diff
255 lines
8.6 KiB
Diff
commit 2f9046fb059e94fe254c9a4ff5bcd52182069e44
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Author: Stefan Liebler <stli@linux.ibm.com>
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Date: Wed Sep 18 12:40:00 2019 +0200
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Add UNSUPPORTED check in elf/tst-pldd.
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The testcase forks a child process and runs pldd with PID of
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this child. On systems where /proc/sys/kernel/yama/ptrace_scope
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differs from zero, pldd will fail with
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/usr/bin/pldd: cannot attach to process 3: Operation not permitted
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This patch checks if ptrace_scope exists, is zero "classic ptrace permissions"
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or one "restricted ptrace". If ptrace_scope exists and has a higher
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restriction, then the test is marked as UNSUPPORTED.
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The case "restricted ptrace" is handled by rearranging the processes involved
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during the test. Now we have the following process tree:
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-parent: do_test (performs output checks)
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--subprocess 1: pldd_process (becomes pldd via execve)
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---subprocess 2: target_process (ptraced via pldd)
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ChangeLog:
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* elf/tst-pldd.c (do_test): Add UNSUPPORTED check.
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Rearrange subprocesses.
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(pldd_process): New function.
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* support/Makefile (libsupport-routines): Add support_ptrace.
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* support/xptrace.h: New file.
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* support/support_ptrace.c: Likewise.
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Conflicts:
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elf/tst-pldd.c
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(Original backport uses spaces instead of tabs.)
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diff --git a/elf/tst-pldd.c b/elf/tst-pldd.c
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index e2de31282a131166..f381cb0fa7e6b93d 100644
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--- a/elf/tst-pldd.c
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+++ b/elf/tst-pldd.c
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@@ -30,6 +30,11 @@
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#include <support/capture_subprocess.h>
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#include <support/check.h>
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#include <support/support.h>
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+#include <support/xptrace.h>
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+#include <support/xunistd.h>
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+#include <sys/mman.h>
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+#include <errno.h>
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+#include <signal.h>
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static void
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target_process (void *arg)
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@@ -37,6 +42,34 @@ target_process (void *arg)
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pause ();
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}
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+static void
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+pldd_process (void *arg)
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+{
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+ pid_t *target_pid_ptr = (pid_t *) arg;
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+
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+ /* Create a copy of current test to check with pldd. As the
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+ target_process is a child of this pldd_process, pldd is also able
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+ to attach to target_process if YAMA is configured to 1 =
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+ "restricted ptrace". */
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+ struct support_subprocess target = support_subprocess (target_process, NULL);
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+
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+ /* Store the pid of target-process as do_test needs it in order to
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+ e.g. terminate it at end of the test. */
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+ *target_pid_ptr = target.pid;
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+
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+ /* Three digits per byte plus null terminator. */
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+ char pid[3 * sizeof (uint32_t) + 1];
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+ snprintf (pid, array_length (pid), "%d", target.pid);
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+
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+ char *prog = xasprintf ("%s/pldd", support_bindir_prefix);
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+
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+ /* Run pldd and use the pid of target_process as argument. */
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+ execve (prog, (char *const []) { (char *) prog, pid, NULL },
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+ (char *const []) { NULL });
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+
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+ FAIL_EXIT1 ("Returned from execve: errno=%d=%m\n", errno);
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+}
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+
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/* The test runs in a container because pldd does not support tracing
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a binary started by the loader iself (as with testrun.sh). */
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@@ -52,25 +85,22 @@ in_str_list (const char *libname, const char *const strlist[])
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static int
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do_test (void)
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{
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- /* Create a copy of current test to check with pldd. */
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- struct support_subprocess target = support_subprocess (target_process, NULL);
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-
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- /* Run 'pldd' on test subprocess. */
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- struct support_capture_subprocess pldd;
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+ /* Check if our subprocess can be debugged with ptrace. */
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{
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- /* Three digits per byte plus null terminator. */
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- char pid[3 * sizeof (uint32_t) + 1];
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- snprintf (pid, array_length (pid), "%d", target.pid);
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-
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- char *prog = xasprintf ("%s/pldd", support_bindir_prefix);
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-
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- pldd = support_capture_subprogram (prog,
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- (char *const []) { (char *) prog, pid, NULL });
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+ int ptrace_scope = support_ptrace_scope ();
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+ if (ptrace_scope >= 2)
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+ FAIL_UNSUPPORTED ("/proc/sys/kernel/yama/ptrace_scope >= 2");
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+ }
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- support_capture_subprocess_check (&pldd, "pldd", 0, sc_allow_stdout);
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+ pid_t *target_pid_ptr = (pid_t *) xmmap (NULL, sizeof (pid_t),
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+ PROT_READ | PROT_WRITE,
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+ MAP_SHARED | MAP_ANONYMOUS, -1);
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- free (prog);
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- }
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+ /* Run 'pldd' on test subprocess which will be created in pldd_process.
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+ The pid of the subprocess will be written to target_pid_ptr. */
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+ struct support_capture_subprocess pldd;
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+ pldd = support_capture_subprocess (pldd_process, target_pid_ptr);
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+ support_capture_subprocess_check (&pldd, "pldd", 0, sc_allow_stdout);
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/* Check 'pldd' output. The test is expected to be linked against only
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loader and libc. */
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@@ -85,15 +115,15 @@ do_test (void)
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/* First line is in the form of <pid>: <full path of executable> */
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TEST_COMPARE (fscanf (out, "%u: " STRINPUT (512), &pid, buffer), 2);
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- TEST_COMPARE (pid, target.pid);
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+ TEST_COMPARE (pid, *target_pid_ptr);
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TEST_COMPARE (strcmp (basename (buffer), "tst-pldd"), 0);
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/* It expects only one loader and libc loaded by the program. */
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bool interpreter_found = false, libc_found = false;
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while (fgets (buffer, array_length (buffer), out) != NULL)
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{
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- /* Ignore vDSO. */
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- if (buffer[0] != '/')
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+ /* Ignore vDSO. */
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+ if (buffer[0] != '/')
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continue;
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/* Remove newline so baseline (buffer) can compare against the
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@@ -128,7 +158,9 @@ do_test (void)
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}
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support_capture_subprocess_free (&pldd);
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- support_process_terminate (&target);
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+ if (kill (*target_pid_ptr, SIGKILL) != 0)
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+ FAIL_EXIT1 ("Unable to kill target_process: errno=%d=%m\n", errno);
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+ xmunmap (target_pid_ptr, sizeof (pid_t));
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return 0;
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}
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diff --git a/support/Makefile b/support/Makefile
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index 65b16299573af1ed..79d03bd6bfe02540 100644
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--- a/support/Makefile
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+++ b/support/Makefile
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@@ -58,6 +58,7 @@ libsupport-routines = \
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support_format_hostent \
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support_format_netent \
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support_isolate_in_subprocess \
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+ support_ptrace \
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support_openpty \
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support_paths \
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support_quote_blob \
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diff --git a/support/support_ptrace.c b/support/support_ptrace.c
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new file mode 100644
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index 0000000000000000..616b08cff33022ef
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--- /dev/null
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+++ b/support/support_ptrace.c
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@@ -0,0 +1,44 @@
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+/* Support functions handling ptrace_scope.
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+ Copyright (C) 2019 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <support/check.h>
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+#include <support/xstdio.h>
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+#include <support/xptrace.h>
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+#include <sys/prctl.h>
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+
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+int
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+support_ptrace_scope (void)
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+{
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+ int ptrace_scope = -1;
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+
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+#ifdef __linux__
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+ /* YAMA may be not enabled. Otherwise it contains a value from 0 to 3:
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+ - 0 classic ptrace permissions
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+ - 1 restricted ptrace
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+ - 2 admin-only attach
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+ - 3 no attach */
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+ FILE *f = fopen ("/proc/sys/kernel/yama/ptrace_scope", "r");
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+ if (f != NULL)
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+ {
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+ TEST_COMPARE (fscanf (f, "%d", &ptrace_scope), 1);
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+ xfclose (f);
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+ }
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+#endif
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+
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+ return ptrace_scope;
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+}
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diff --git a/support/xptrace.h b/support/xptrace.h
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new file mode 100644
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index 0000000000000000..7af892680578fffd
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--- /dev/null
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+++ b/support/xptrace.h
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@@ -0,0 +1,32 @@
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+/* Support functions handling ptrace_scope.
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+ Copyright (C) 2019 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#ifndef SUPPORT_PTRACE_H
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+#define SUPPORT_PTRACE_H
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+
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+#include <sys/cdefs.h>
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+
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+__BEGIN_DECLS
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+
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+/* Return the current YAMA mode set on the machine (0 to 3) or -1
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+ if YAMA is not supported. */
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+int support_ptrace_scope (void);
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+
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+__END_DECLS
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+
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+#endif
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