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http://sourceware.org/ml/gdb-patches/2012-03/msg00171.html
Subject: [patch 3/3] attach-fail-reasons: SELinux deny_ptrace
Hi,
and here is the last bit for new SELinux 'deny_ptrace':
https://bugzilla.redhat.com/show_bug.cgi?id=786878
As even PTRACE_TRACEME fails in such case it needs to install hook for even
that event.
Thanks,
Jan
gdb/
2012-03-06 Jan Kratochvil <jan.kratochvil@redhat.com>
* common/linux-ptrace.c [HAVE_SELINUX_SELINUX_H]: include
selinux/selinux.h.
(linux_ptrace_attach_warnings): Call linux_ptrace_create_warnings.
(linux_ptrace_create_warnings): New.
* common/linux-ptrace.h (linux_ptrace_create_warnings): New declaration.
* config.in: Regenerate.
* configure: Regenerate.
* configure.ac: Check selinux/selinux.h and the selinux library.
* inf-ptrace.c (inf_ptrace_me): Check the ptrace result.
* linux-nat.c (linux_nat_create_inferior): New variable ex. Wrap
to_create_inferior into TRY_CATCH, call linux_ptrace_create_warnings.
gdb/gdbserver/
* config.in: Regenerate.
* configure: Regenerate.
* configure.ac: Check selinux/selinux.h and the selinux library.
* linux-low.c (linux_traceme): New function.
(linux_create_inferior, linux_tracefork_child): Call it instead of
direct ptrace.
Index: gdb-7.5.50.20130215/gdb/common/linux-ptrace.c
===================================================================
--- gdb-7.5.50.20130215.orig/gdb/common/linux-ptrace.c 2013-01-08 20:38:51.000000000 +0100
+++ gdb-7.5.50.20130215/gdb/common/linux-ptrace.c 2013-02-15 22:38:05.782456279 +0100
@@ -29,6 +29,10 @@
#include "gdb_assert.h"
#include "gdb_wait.h"
+#ifdef HAVE_SELINUX_SELINUX_H
+# include <selinux/selinux.h>
+#endif /* HAVE_SELINUX_SELINUX_H */
+
/* Find all possible reasons we could fail to attach PID and append these
newline terminated reason strings to initialized BUFFER. '\0' termination
of BUFFER must be done by the caller. */
@@ -48,6 +52,8 @@ linux_ptrace_attach_warnings (pid_t pid,
buffer_xml_printf (buffer, _("warning: process %d is a zombie "
"- the process has already terminated\n"),
(int) pid);
+
+ linux_ptrace_create_warnings (buffer);
}
#if defined __i386__ || defined __x86_64__
@@ -243,3 +249,19 @@ linux_ptrace_init_warnings (void)
linux_ptrace_test_ret_to_nx ();
}
+
+/* Print all possible reasons we could fail to create a traced process. */
+
+void
+linux_ptrace_create_warnings (struct buffer *buffer)
+{
+#ifdef HAVE_LIBSELINUX
+ /* -1 is returned for errors, 0 if it has no effect, 1 if PTRACE_ATTACH is
+ forbidden. */
+ if (security_get_boolean_active ("deny_ptrace") == 1)
+ buffer_xml_printf (buffer,
+ _("the SELinux boolean 'deny_ptrace' is enabled, "
+ "you can disable this process attach protection by: "
+ "(gdb) shell sudo setsebool deny_ptrace=0"));
+#endif /* HAVE_LIBSELINUX */
+}
Index: gdb-7.5.50.20130215/gdb/common/linux-ptrace.h
===================================================================
--- gdb-7.5.50.20130215.orig/gdb/common/linux-ptrace.h 2013-01-01 07:32:54.000000000 +0100
+++ gdb-7.5.50.20130215/gdb/common/linux-ptrace.h 2013-02-15 22:38:05.782456279 +0100
@@ -69,5 +69,6 @@ struct buffer;
extern void linux_ptrace_attach_warnings (pid_t pid, struct buffer *buffer);
extern void linux_ptrace_init_warnings (void);
+extern void linux_ptrace_create_warnings (struct buffer *buffer);
#endif /* COMMON_LINUX_PTRACE_H */
Index: gdb-7.5.50.20130215/gdb/configure.ac
===================================================================
--- gdb-7.5.50.20130215.orig/gdb/configure.ac 2013-02-15 22:37:57.000000000 +0100
+++ gdb-7.5.50.20130215/gdb/configure.ac 2013-02-15 22:38:05.783456281 +0100
@@ -2068,6 +2068,10 @@ then
[Define if you support the personality syscall.])
fi
+dnl Check security_get_boolean_active availability.
+AC_CHECK_HEADERS(selinux/selinux.h)
+AC_CHECK_LIB(selinux, security_get_boolean_active)
+
dnl Handle optional features that can be enabled.
# Support for --with-sysroot is a copy of GDB_AC_WITH_DIR,
Index: gdb-7.5.50.20130215/gdb/gdbserver/configure.ac
===================================================================
--- gdb-7.5.50.20130215.orig/gdb/gdbserver/configure.ac 2013-01-01 07:33:00.000000000 +0100
+++ gdb-7.5.50.20130215/gdb/gdbserver/configure.ac 2013-02-15 22:38:05.783456281 +0100
@@ -451,6 +451,10 @@ if $want_ipa ; then
fi
fi
+dnl Check security_get_boolean_active availability.
+AC_CHECK_HEADERS(selinux/selinux.h)
+AC_CHECK_LIB(selinux, security_get_boolean_active)
+
AC_SUBST(GDBSERVER_DEPFILES)
AC_SUBST(GDBSERVER_LIBS)
AC_SUBST(USE_THREAD_DB)
Index: gdb-7.5.50.20130215/gdb/gdbserver/linux-low.c
===================================================================
--- gdb-7.5.50.20130215.orig/gdb/gdbserver/linux-low.c 2013-02-04 18:47:00.000000000 +0100
+++ gdb-7.5.50.20130215/gdb/gdbserver/linux-low.c 2013-02-15 22:39:54.256591069 +0100
@@ -602,6 +602,29 @@ add_lwp (ptid_t ptid)
return lwp;
}
+/* Execute PTRACE_TRACEME with error checking. */
+
+static void
+linux_traceme (const char *program)
+{
+ int save_errno;
+ struct buffer buffer;
+
+ errno = 0;
+ if (ptrace (PTRACE_TRACEME, 0,
+ (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0) == 0)
+ return;
+
+ save_errno = errno;
+ buffer_init (&buffer);
+ linux_ptrace_create_warnings (&buffer);
+ buffer_grow_str0 (&buffer, "");
+ fprintf (stderr, _("%sCannot trace created process %s: %s.\n"),
+ buffer_finish (&buffer), program, strerror (save_errno));
+ fflush (stderr);
+ _exit (0177);
+}
+
/* Start an inferior process and returns its pid.
ALLARGS is a vector of program-name and args. */
@@ -642,7 +665,7 @@ linux_create_inferior (char *program, ch
if (pid == 0)
{
- ptrace (PTRACE_TRACEME, 0, (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0);
+ linux_traceme (program);
#ifndef __ANDROID__ /* Bionic doesn't use SIGRTMIN the way glibc does. */
signal (__SIGRTMIN + 1, SIG_DFL);
@@ -4587,7 +4610,7 @@ linux_tracefork_grandchild (void *arg)
static int
linux_tracefork_child (void *arg)
{
- ptrace (PTRACE_TRACEME, 0, (PTRACE_ARG3_TYPE) 0, (PTRACE_ARG4_TYPE) 0);
+ linux_traceme ("PTRACE_O_TRACEFORK test");
kill (getpid (), SIGSTOP);
#if !(defined(__UCLIBC__) && defined(HAS_NOMMU))
Index: gdb-7.5.50.20130215/gdb/inf-ptrace.c
===================================================================
--- gdb-7.5.50.20130215.orig/gdb/inf-ptrace.c 2013-01-01 07:32:45.000000000 +0100
+++ gdb-7.5.50.20130215/gdb/inf-ptrace.c 2013-02-15 22:38:05.786456289 +0100
@@ -104,7 +104,15 @@ static void
inf_ptrace_me (void)
{
/* "Trace me, Dr. Memory!" */
+ errno = 0;
ptrace (PT_TRACE_ME, 0, (PTRACE_TYPE_ARG3)0, 0);
+ if (errno != 0)
+ {
+ fprintf_unfiltered (gdb_stderr, _("Cannot create process: %s\n"),
+ safe_strerror (errno));
+ gdb_flush (gdb_stderr);
+ _exit (0177);
+ }
}
/* Start a new inferior Unix child process. EXEC_FILE is the file to
Index: gdb-7.5.50.20130215/gdb/linux-nat.c
===================================================================
--- gdb-7.5.50.20130215.orig/gdb/linux-nat.c 2013-02-15 22:34:44.000000000 +0100
+++ gdb-7.5.50.20130215/gdb/linux-nat.c 2013-02-15 22:38:05.787456291 +0100
@@ -1557,6 +1557,7 @@ linux_nat_create_inferior (struct target
#ifdef HAVE_PERSONALITY
int personality_orig = 0, personality_set = 0;
#endif /* HAVE_PERSONALITY */
+ volatile struct gdb_exception ex;
/* The fork_child mechanism is synchronous and calls target_wait, so
we have to mask the async mode. */
@@ -1581,7 +1582,10 @@ linux_nat_create_inferior (struct target
/* Make sure we report all signals during startup. */
linux_nat_pass_signals (0, NULL);
- linux_ops->to_create_inferior (ops, exec_file, allargs, env, from_tty);
+ TRY_CATCH (ex, RETURN_MASK_ERROR)
+ {
+ linux_ops->to_create_inferior (ops, exec_file, allargs, env, from_tty);
+ }
#ifdef HAVE_PERSONALITY
if (personality_set)
@@ -1593,6 +1597,24 @@ linux_nat_create_inferior (struct target
safe_strerror (errno));
}
#endif /* HAVE_PERSONALITY */
+
+ if (ex.reason < 0)
+ {
+ struct buffer buffer;
+ char *message, *buffer_s;
+
+ message = xstrdup (ex.message);
+ make_cleanup (xfree, message);
+
+ buffer_init (&buffer);
+ linux_ptrace_create_warnings (&buffer);
+
+ buffer_grow_str0 (&buffer, "");
+ buffer_s = buffer_finish (&buffer);
+ make_cleanup (xfree, buffer_s);
+
+ throw_error (ex.error, "%s%s", buffer_s, message);
+ }
}
static void
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