From 8eefbac3b67756f0dfe9d68741d70015023b5216 Mon Sep 17 00:00:00 2001

From: Martin Milata <mmilata@redhat.com>

Date: Fri, 17 Jul 2015 12:52:49 +0200

Subject: [PATCH] Create core backtrace in unwind hook

Related to #829.

We need to implement #882 in order for this to work. This change

requires (yet unreleased) satyr-0.16.

The feature is turned off by default, you need to pass

--enable-dump-time-unwind to configure in order to enable it.

Signed-off-by: Martin Milata <mmilata@redhat.com>

Conflicts:

	src/hooks/abrt-hook-ccpp.c

---

 configure.ac                        |  12 ++++

 doc/abrt-CCpp.conf.txt              |  18 ++++++

 src/hooks/CCpp.conf                 |  15 +++++

 src/hooks/abrt-hook-ccpp.c          | 108 ++++++++++++++++++++++++------------

 src/hooks/abrt-install-ccpp-hook.in |   4 +-

 5 files changed, 121 insertions(+), 36 deletions(-)

diff --git a/configure.ac b/configure.ac

index 56b8ad8..330dd9c 100644

--- a/configure.ac

+++ b/configure.ac

@@ -232,6 +232,18 @@ AC_ARG_ENABLE([native-unwinder],

 [fi]

+# Perform stack unwind on live/dying process in the core handler?

+

+AC_ARG_ENABLE([dump-time-unwind],

+    AS_HELP_STRING([--enable-dump-time-unwind],

+        [create core stack trace while the crashed process is still in memory (default is no)]),

+    [], [enable_dump_time_unwind=no])

+

+[if test "$enable_native_unwinder" = "yes" -a "$enable_dump_time_unwind" = "yes"]

+[then]

+    AC_DEFINE([ENABLE_DUMP_TIME_UNWIND], [1], [Create core stacktrace while the process is still in memory.])

+[fi]

+

 AC_SUBST(CONF_DIR)

 AC_SUBST(DEFAULT_CONF_DIR)

 AC_SUBST(VAR_RUN)

diff --git a/doc/abrt-CCpp.conf.txt b/doc/abrt-CCpp.conf.txt

index ad3830b..498d53d 100644

--- a/doc/abrt-CCpp.conf.txt

+++ b/doc/abrt-CCpp.conf.txt

@@ -19,12 +19,30 @@ SaveBinaryImage = 'yes' / 'no' ...::

    Useful, for example, when _deleted binary_ segfaults.

    Default is 'no'.

+CreateCoreBacktrace = 'yes' / 'no' ...::

+   When this option is set to 'yes', core backtrace is generated

+   from the memory image of the crashing process. Only the crash

+   thread is present in the backtrace. This feature requires

+   kernel 3.18 or newer, otherwise the core backtrace is not

+   created.

+   Default is 'yes'.

+

+SaveFullCore = 'yes' / 'no' ...::

+   Save full coredump? If set to 'no', coredump won't be saved

+   and you won't be able to report the crash to Bugzilla. Only

+   useful with 'CreateCoreBacktrace' set to 'yes'. Please

+   note that if this option is set to 'no' and MakeCompatCore

+   is set to 'yes', the core is still written to the current

+   directory.

+   Default is 'yes'.

+

 VerboseLog = NUM::

    Used to make the hook more verbose

 SEE ALSO

 --------

 abrt.conf(5)

+abrt-action-generate-core-backtrace(1)

 AUTHORS

 -------

diff --git a/src/hooks/CCpp.conf b/src/hooks/CCpp.conf

index d199116..b1a0a22 100644

--- a/src/hooks/CCpp.conf

+++ b/src/hooks/CCpp.conf

@@ -8,6 +8,21 @@ MakeCompatCore = yes

 # (useful, for example, when _deleted binary_ segfaults)

 SaveBinaryImage = no

+# When this option is set to 'yes', core backtrace is generated

+# from the memory image of the crashing process. Only the crash

+# thread is present in the backtrace. This feature requires

+# kernel 3.18 or newer, otherwise the core backtrace is not

+# created.

+CreateCoreBacktrace = yes

+

+# Save full coredump? If set to 'no', coredump won't be saved

+# and you won't be able to report the crash to Bugzilla. Only

+# useful with CreateCoreBacktrace set to 'yes'. Please

+# note that if this option is set to 'no' and MakeCompatCore

+# is set to 'yes', the core is still written to the current

+# directory.

+SaveFullCore = yes

+

 # Used for debugging the hook

 #VerboseLog = 2

diff --git a/src/hooks/abrt-hook-ccpp.c b/src/hooks/abrt-hook-ccpp.c

index 2dd9ac6..b5f00f6 100644

--- a/src/hooks/abrt-hook-ccpp.c

+++ b/src/hooks/abrt-hook-ccpp.c

@@ -22,6 +22,11 @@

 #include "libabrt.h"

 #include <selinux/selinux.h>

+#ifdef ENABLE_DUMP_TIME_UNWIND

+#include <satyr/abrt.h>

+#include <satyr/utils.h>

+#endif /* ENABLE_DUMP_TIME_UNWIND */

+

 #define  DUMP_SUID_UNSAFE 1

 #define  DUMP_SUID_SAFE 2

@@ -155,13 +160,13 @@ static struct dump_dir *dd;

  * %g - gid

  * %t - UNIX time of dump

  * %e - executable filename

- * %h - hostname

+ * %i - crash thread tid

  * %% - output one "%"

  */

 /* Hook must be installed with exactly the same sequence of %c specifiers.

  * Last one, %h, may be omitted (we can find it out).

  */

-static const char percent_specifiers[] = "%scpugteh";

+static const char percent_specifiers[] = "%scpugtei";

 static char *core_basename = (char*) "core";

 static char* get_executable(pid_t pid, int *fd_p)

@@ -580,6 +585,24 @@ static int create_or_die(const char *filename, int user_core_fd)

     perror_msg_and_die("Can't open '%s'", filename);

 }

+static void create_core_backtrace(pid_t tid, const char *executable, int signal_no, const char *dd_path)

+{

+#ifdef ENABLE_DUMP_TIME_UNWIND

+    if (g_verbose > 1)

+        sr_debug_parser = true;

+

+    char *error_message = NULL;

+    bool success = sr_abrt_create_core_stacktrace_from_core_hook(dd_path, tid, executable,

+                                                                 signal_no, &error_message);

+

+    if (!success)

+    {

+        log("Failed to create core_backtrace: %s", error_message);

+        free(error_message);

+    }

+#endif /* ENABLE_DUMP_TIME_UNWIND */

+}

+

 static int create_user_core(int user_core_fd, pid_t pid, off_t ulimit_c)

 {

     int err = 1;

@@ -619,9 +642,9 @@ int main(int argc, char** argv)

     if (argc < 8)

     {

-        /* percent specifier:         %s   %c              %p  %u  %g  %t   %e          %h */

+        /* percent specifier:         %s   %c              %p  %u  %g  %t   %e          %i */

         /* argv:                  [0] [1]  [2]             [3] [4] [5] [6]  [7]         [8]*/

-        error_msg_and_die("Usage: %s SIGNO CORE_SIZE_LIMIT PID UID GID TIME BINARY_NAME [HOSTNAME]", argv[0]);

+        error_msg_and_die("Usage: %s SIGNO CORE_SIZE_LIMIT PID UID GID TIME BINARY_NAME [TID]", argv[0]);

     }

     /* Not needed on 2.6.30.

@@ -646,6 +669,8 @@ int main(int argc, char** argv)

     /* ... and plugins/CCpp.conf */

     bool setting_MakeCompatCore;

     bool setting_SaveBinaryImage;

+    bool setting_SaveFullCore;

+    bool setting_CreateCoreBacktrace;

     {

         map_string_t *settings = new_map_string();

         load_abrt_plugin_conf_file("CCpp.conf", settings);

@@ -654,6 +679,10 @@ int main(int argc, char** argv)

         setting_MakeCompatCore = value && string_to_bool(value);

         value = get_map_string_item_or_NULL(settings, "SaveBinaryImage");

         setting_SaveBinaryImage = value && string_to_bool(value);

+        value = get_map_string_item_or_NULL(settings, "SaveFullCore");

+        setting_SaveFullCore = value ? string_to_bool(value) : true;

+        value = get_map_string_item_or_NULL(settings, "CreateCoreBacktrace");

+        setting_CreateCoreBacktrace = value ? string_to_bool(value) : true;

         value = get_map_string_item_or_NULL(settings, "VerboseLog");

         if (value)

             g_verbose = xatoi_positive(value);

@@ -686,11 +715,10 @@ int main(int argc, char** argv)

             free(s);

     }

-    struct utsname uts;

-    if (!argv[8]) /* no HOSTNAME? */

+    pid_t tid = 0;

+    if (argv[8])

     {

-        uname(&uts;;

-        argv[8] = uts.nodename;

+        tid = xatoi_positive(argv[8]);

     }

     char path[PATH_MAX];

@@ -906,36 +934,42 @@ int main(int argc, char** argv)

             off_t sz = copyfd_eof(src_fd_binary, dst_fd, COPYFD_SPARSE);

             if (fsync(dst_fd) != 0 || close(dst_fd) != 0 || sz < 0)

             {

-                dd_delete(dd);

-                error_msg_and_die("Error saving '%s'", path);

+                dd_delete(dd); error_msg_and_die("Error saving '%s'", path);

             }

             close(src_fd_binary);

         }

-        strcpy(path + path_len, "/"FILENAME_COREDUMP);

-        int abrt_core_fd = create_or_die(path, user_core_fd);

-

-        /* We write both coredumps at once.

-         * We can't write user coredump first, since it might be truncated

-         * and thus can't be copied and used as abrt coredump;

-         * and if we write abrt coredump first and then copy it as user one,

-         * then we have a race when process exits but coredump does not exist yet:

-         * $ echo -e '#include<signal.h>\nmain(){raise(SIGSEGV);}' | gcc -o test -x c -

-         * $ rm -f core*; ulimit -c unlimited; ./test; ls -l core*

-         * 21631 Segmentation fault (core dumped) ./test

-         * ls: cannot access core*: No such file or directory <=== BAD

-         */

-        off_t core_size = copyfd_sparse(STDIN_FILENO, abrt_core_fd, user_core_fd, ulimit_c);

-

-        close_user_core(user_core_fd, core_size);

-

-        if (fsync(abrt_core_fd) != 0 || close(abrt_core_fd) != 0 || core_size < 0)

+        off_t core_size = 0;

+        if (setting_SaveFullCore)

         {

-            unlink(path);

-            dd_delete(dd);

-            /* copyfd_sparse logs the error including errno string,

-             * but it does not log file name */

-            error_msg_and_die("Error writing '%s'", path);

+            strcpy(path + path_len, "/"FILENAME_COREDUMP);

+            int abrt_core_fd = create_or_die(path, user_core_fd);

+

+            /* We write both coredumps at once.

+             * We can't write user coredump first, since it might be truncated

+             * and thus can't be copied and used as abrt coredump;

+             * and if we write abrt coredump first and then copy it as user one,

+             * then we have a race when process exits but coredump does not exist yet:

+             * $ echo -e '#include<signal.h>\nmain(){raise(SIGSEGV);}' | gcc -o test -x c -

+             * $ rm -f core*; ulimit -c unlimited; ./test; ls -l core*

+             * 21631 Segmentation fault (core dumped) ./test

+             * ls: cannot access core*: No such file or directory <=== BAD

+             */

+            core_size = copyfd_sparse(STDIN_FILENO, abrt_core_fd, user_core_fd, ulimit_c);

+            close_user_core(user_core_fd, core_size);

+            if (fsync(abrt_core_fd) != 0 || close(abrt_core_fd) != 0 || core_size < 0)

+            {

+                unlink(path);

+                dd_delete(dd);

+                /* copyfd_sparse logs the error including errno string,

+                 * but it does not log file name */

+                error_msg_and_die("Error writing '%s'", path);

+            }

+        }

+        else

+        {

+            /* User core is created even if WriteFullCore is off. */

+            create_user_core(user_core_fd, pid, ulimit_c);

         }

 /* Because of #1211835 and #1126850 */

@@ -977,6 +1011,10 @@ int main(int argc, char** argv)

         /* And finally set the right uid and gid */

         dd_reset_ownership(dd);

+        /* Perform crash-time unwind of the guilty thread. */

+        if (tid > 0 && setting_CreateCoreBacktrace)

+            create_core_backtrace(tid, executable, signal_no, dd->dd_dirname);

+

         /* We close dumpdir before we start catering for crash storm case.

          * Otherwise, delete_dump_dir's from other concurrent

          * CCpp's won't be able to delete our dump (their delete_dump_dir

@@ -990,7 +1028,9 @@ int main(int argc, char** argv)

             strcpy(path, newpath);

         free(newpath);

-        log("Saved core dump of pid %lu (%s) to %s (%llu bytes)", (long)pid, executable, path, (long long)core_size);

+        if (core_size > 0)

+            log_notice("Saved core dump of pid %lu (%s) to %s (%llu bytes)",

+                       (long)pid, executable, path, (long long)core_size);

         notify_new_path(path);

diff --git a/src/hooks/abrt-install-ccpp-hook.in b/src/hooks/abrt-install-ccpp-hook.in

index aa01231..d4ed4a5 100755

--- a/src/hooks/abrt-install-ccpp-hook.in

+++ b/src/hooks/abrt-install-ccpp-hook.in

@@ -11,9 +11,9 @@ SAVED_PATTERN_DIR="@VAR_RUN@/abrt"

 SAVED_PATTERN_FILE="@VAR_RUN@/abrt/saved_core_pattern"

 HOOK_BIN="@libexecdir@/abrt-hook-ccpp"

 # Must match percent_specifiers[] order in abrt-hook-ccpp.c:

-PATTERN="|$HOOK_BIN %s %c %p %u %g %t %e"

+PATTERN="|$HOOK_BIN %s %c %p %u %g %t %e %i"

 # Same, but with bogus "executable name" parameter

-PATTERN1="|$HOOK_BIN %s %c %p %u %g %t e"

+PATTERN1="|$HOOK_BIN %s %c %p %u %g %t e %i"

 # core_pipe_limit specifies how many dump_helpers can run at the same time

 # 0 - means unlimited, but it's not guaranteed that /proc/<pid> of crashing

-- 

2.4.3