[PATCH] Provide a simple backtrace in the samba AD DC also
Jeremy Allison
jra at samba.org
Tue Apr 10 20:59:43 UTC 2018
On Tue, Apr 10, 2018 at 05:00:32PM +1200, Andrew Bartlett via samba-technical wrote:
> smbd has for a long time been able to produce a simple internal
> backtrace.
>
> This patch allows 'samba' to do the same, by bringing that code into
> lib/util. An un-used IRIX mode, lost since the move to waf, was
> removed to allow this to happen. (That mode used become_root()).
>
> This is important because gdb_backtrace as a panic action is not
> compatible with gitlab CI, so without this we have no way to tell where
> the fault is.
>
> The cstyle.py failures are all in the moved code:
>
> ad84ecfd836 s3-lib: Remove support for libexc for IRIX backtraces
> 2469ab654a3 lib/util: Log PANIC before calling pacic action just like
> s3
> 212ae4db4bb lib/util: Move log_stack_trace() to common code
> :lib/util/fault.c:
> 178 Comment line does not have * aligned with top
> 179 Comment line does not have * aligned with top
> 180 Comment line does not have * aligned with top
> 181 Garbage before * in comment line
> 181 Comment is 3+ lines but is not formatted as block comment
> 197 Preprocessor statement in function body
> 201 Comment is 3+ lines but is not formatted as block comment
> 227 Space before close parenthesis
> 234 Space after cast operator (or inline if/while body)
> 242 Space after cast operator (or inline if/while body)
> 252 Preprocessor statement in function body
> 273 Preprocessor statement in function body
> 275 Preprocessor statement in function body
> 19dba766ad6 lib/util: Call log_stack_trace() in smb_panic_default()
>
> Please review and push,
LGTM - RB+ and pushed with the minor change of DEBUG(0, -> DBG_ERR(
to match updated coding standards.
Cheers,
Jeremy
> Andrew Bartlett
> https://samba.org/~abartlet/
> Authentication Developer, Samba Team https://samba.org
> Samba Development and Support, Catalyst IT
> https://catalyst.net.nz/services/samba
>
>
>
> From ad84ecfd836f07bbfe050fe203d352490c85decc Mon Sep 17 00:00:00 2001
> From: Andrew Bartlett <abartlet at samba.org>
> Date: Tue, 10 Apr 2018 15:54:10 +1200
> Subject: [PATCH 1/4] s3-lib: Remove support for libexc for IRIX backtraces
>
> IRIX is long dead, and this code needs become_root() which is not in
> the top level code.
>
> Additionally, the check for libexc never made it into waf, so this
> has been dead code since Samba 4.1.
>
> Signed-off-by: Andrew Bartlett <abartlet at samba.org>
> ---
> source3/lib/util.c | 42 ------------------------------------------
> source3/wscript | 2 +-
> 2 files changed, 1 insertion(+), 43 deletions(-)
>
> diff --git a/source3/lib/util.c b/source3/lib/util.c
> index ae9fe71c974..98c47b3df9f 100644
> --- a/source3/lib/util.c
> +++ b/source3/lib/util.c
> @@ -852,10 +852,6 @@ void smb_panic_s3(const char *why)
> #include <execinfo.h>
> #endif
>
> -#ifdef HAVE_LIBEXC_H
> -#include <libexc.h>
> -#endif
> -
> void log_stack_trace(void)
> {
> #ifdef HAVE_LIBUNWIND
> @@ -934,44 +930,6 @@ libunwind_failed:
> /* Leak the backtrace_strings, rather than risk what free() might do */
> }
>
> -#elif HAVE_LIBEXC
> -
> - /* The IRIX libexc library provides an API for unwinding the stack. See
> - * libexc(3) for details. Apparantly trace_back_stack leaks memory, but
> - * since we are about to abort anyway, it hardly matters.
> - */
> -
> -#define NAMESIZE 32 /* Arbitrary */
> -
> - __uint64_t addrs[BACKTRACE_STACK_SIZE];
> - char * names[BACKTRACE_STACK_SIZE];
> - char namebuf[BACKTRACE_STACK_SIZE * NAMESIZE];
> -
> - int i;
> - int levels;
> -
> - ZERO_ARRAY(addrs);
> - ZERO_ARRAY(names);
> - ZERO_ARRAY(namebuf);
> -
> - /* We need to be root so we can open our /proc entry to walk
> - * our stack. It also helps when we want to dump core.
> - */
> - become_root();
> -
> - for (i = 0; i < BACKTRACE_STACK_SIZE; i++) {
> - names[i] = namebuf + (i * NAMESIZE);
> - }
> -
> - levels = trace_back_stack(0, addrs, names,
> - BACKTRACE_STACK_SIZE, NAMESIZE - 1);
> -
> - DEBUG(0, ("BACKTRACE: %d stack frames:\n", levels));
> - for (i = 0; i < levels; i++) {
> - DEBUGADD(0, (" #%d 0x%llx %s\n", i, addrs[i], names[i]));
> - }
> -#undef NAMESIZE
> -
> #else
> DEBUG(0, ("unable to produce a stack trace on this platform\n"));
> #endif
> diff --git a/source3/wscript b/source3/wscript
> index 826877d3dfd..8d658b2f53e 100644
> --- a/source3/wscript
> +++ b/source3/wscript
> @@ -96,7 +96,7 @@ def configure(conf):
> # We crash without vfs_default
> required_static_modules.extend(TO_LIST('vfs_default'))
>
> - conf.CHECK_HEADERS('execinfo.h libexc.h libunwind.h netdb.h')
> + conf.CHECK_HEADERS('execinfo.h libunwind.h netdb.h')
> conf.CHECK_HEADERS('linux/falloc.h linux/ioctl.h')
>
> conf.CHECK_FUNCS('getcwd fchown chmod fchmod mknod')
> --
> 2.11.0
>
>
> From 2469ab654a3c39099ec6423acb5927182849a3b1 Mon Sep 17 00:00:00 2001
> From: Andrew Bartlett <abartlet at samba.org>
> Date: Tue, 10 Apr 2018 16:06:12 +1200
> Subject: [PATCH 2/4] lib/util: Log PANIC before calling pacic action just like
> s3
>
> This is like the changes made in s3 by
> 4fa555980070d78b39711ef21d77628d26055bc2
>
> Signed-off-by: Andrew Bartlett <abartlet at samba.org>
> ---
> lib/util/fault.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/lib/util/fault.c b/lib/util/fault.c
> index 54d84711742..887c7d6c238 100644
> --- a/lib/util/fault.c
> +++ b/lib/util/fault.c
> @@ -123,6 +123,9 @@ _PUBLIC_ const char *panic_action = NULL;
> static void smb_panic_default(const char *why) _NORETURN_;
> static void smb_panic_default(const char *why)
> {
> + DEBUG(0,("PANIC (pid %llu): %s\n",
> + (unsigned long long)getpid(), why));
> +
> #if defined(HAVE_PRCTL) && defined(PR_SET_PTRACER)
> /*
> * Make sure all children can attach a debugger.
> @@ -148,7 +151,6 @@ static void smb_panic_default(const char *why)
> WEXITSTATUS(result)));
> }
> }
> - DEBUG(0,("PANIC: %s\n", why));
>
> #ifdef SIGABRT
> CatchSignal(SIGABRT, SIG_DFL);
> --
> 2.11.0
>
>
> From 212ae4db4bb433de5e3a70fcb797c6dc21f4d795 Mon Sep 17 00:00:00 2001
> From: Andrew Bartlett <abartlet at samba.org>
> Date: Tue, 10 Apr 2018 16:35:07 +1200
> Subject: [PATCH 3/4] lib/util: Move log_stack_trace() to common code
>
> Signed-off-by: Andrew Bartlett <abartlet at samba.org>
> ---
> lib/util/fault.c | 104 +++++++++++++++++++++++++++++++++++++++++++++
> lib/util/fault.h | 1 +
> lib/util/wscript_configure | 1 +
> source3/include/local.h | 3 --
> source3/include/proto.h | 1 -
> source3/lib/util.c | 97 ------------------------------------------
> source3/wscript | 2 +-
> 7 files changed, 107 insertions(+), 102 deletions(-)
>
> diff --git a/lib/util/fault.c b/lib/util/fault.c
> index 887c7d6c238..af06c9484db 100644
> --- a/lib/util/fault.c
> +++ b/lib/util/fault.c
> @@ -3,6 +3,7 @@
> Critical Fault handling
> Copyright (C) Andrew Tridgell 1992-1998
> Copyright (C) Tim Prouty 2009
> + Copyright (C) James Peach 2006
>
> This program is free software; you can redistribute it and/or modify
> it under the terms of the GNU General Public License as published by
> @@ -170,3 +171,106 @@ _PUBLIC_ void smb_panic(const char *why)
> }
> smb_panic_default(why);
> }
> +
> +
> +
> +/*******************************************************************
> + Print a backtrace of the stack to the debug log. This function
> + DELIBERATELY LEAKS MEMORY. The expectation is that you should
> + exit shortly after calling it.
> +********************************************************************/
> +
> +/* Buffer size to use when printing backtraces */
> +#define BACKTRACE_STACK_SIZE 64
> +
> +
> +#ifdef HAVE_LIBUNWIND_H
> +#include <libunwind.h>
> +#endif
> +
> +#ifdef HAVE_EXECINFO_H
> +#include <execinfo.h>
> +#endif
> +
> +void log_stack_trace(void)
> +{
> +#ifdef HAVE_LIBUNWIND
> + /* Try to use libunwind before any other technique since on ia64
> + * libunwind correctly walks the stack in more circumstances than
> + * backtrace.
> + */
> + unw_cursor_t cursor;
> + unw_context_t uc;
> + unsigned i = 0;
> +
> + char procname[256];
> + unw_word_t ip, sp, off;
> +
> + procname[sizeof(procname) - 1] = '\0';
> +
> + if (unw_getcontext(&uc) != 0) {
> + goto libunwind_failed;
> + }
> +
> + if (unw_init_local(&cursor, &uc) != 0) {
> + goto libunwind_failed;
> + }
> +
> + DEBUG(0, ("BACKTRACE:\n"));
> +
> + do {
> + ip = sp = 0;
> + unw_get_reg(&cursor, UNW_REG_IP, &ip);
> + unw_get_reg(&cursor, UNW_REG_SP, &sp);
> +
> + switch (unw_get_proc_name(&cursor,
> + procname, sizeof(procname) - 1, &off) ) {
> + case 0:
> + /* Name found. */
> + case -UNW_ENOMEM:
> + /* Name truncated. */
> + DEBUGADD(0, (" #%u %s + %#llx [ip=%#llx] [sp=%#llx]\n",
> + i, procname, (long long)off,
> + (long long)ip, (long long) sp));
> + break;
> + default:
> + /* case -UNW_ENOINFO: */
> + /* case -UNW_EUNSPEC: */
> + /* No symbol name found. */
> + DEBUGADD(0, (" #%u %s [ip=%#llx] [sp=%#llx]\n",
> + i, "<unknown symbol>",
> + (long long)ip, (long long) sp));
> + }
> + ++i;
> + } while (unw_step(&cursor) > 0);
> +
> + return;
> +
> +libunwind_failed:
> + DEBUG(0, ("unable to produce a stack trace with libunwind\n"));
> +
> +#elif HAVE_BACKTRACE_SYMBOLS
> + void *backtrace_stack[BACKTRACE_STACK_SIZE];
> + size_t backtrace_size;
> + char **backtrace_strings;
> +
> + /* get the backtrace (stack frames) */
> + backtrace_size = backtrace(backtrace_stack,BACKTRACE_STACK_SIZE);
> + backtrace_strings = backtrace_symbols(backtrace_stack, backtrace_size);
> +
> + DEBUG(0, ("BACKTRACE: %lu stack frames:\n",
> + (unsigned long)backtrace_size));
> +
> + if (backtrace_strings) {
> + int i;
> +
> + for (i = 0; i < backtrace_size; i++)
> + DEBUGADD(0, (" #%u %s\n", i, backtrace_strings[i]));
> +
> + /* Leak the backtrace_strings, rather than risk what free() might do */
> + }
> +
> +#else
> + DEBUG(0, ("unable to produce a stack trace on this platform\n"));
> +#endif
> +}
> diff --git a/lib/util/fault.h b/lib/util/fault.h
> index 0ac6cb9ceb5..dfa339b7650 100644
> --- a/lib/util/fault.h
> +++ b/lib/util/fault.h
> @@ -53,5 +53,6 @@ void fault_setup(void);
> void fault_setup_disable(void);
> _NORETURN_ void smb_panic(const char *reason);
>
> +void log_stack_trace(void);
>
> #endif /* _SAMBA_FAULT_H_ */
> diff --git a/lib/util/wscript_configure b/lib/util/wscript_configure
> index 8e5a59c8480..2a8dbef699b 100644
> --- a/lib/util/wscript_configure
> +++ b/lib/util/wscript_configure
> @@ -6,6 +6,7 @@ if Options.options.disable_fault_handling:
>
> # backtrace could be in libexecinfo or in libc
> conf.CHECK_FUNCS_IN('backtrace backtrace_symbols', 'execinfo', checklibc=True, headers='execinfo.h')
> +conf.CHECK_HEADERS('execinfo.h libunwind.h')
>
> conf.CHECK_STRUCTURE_MEMBER('struct statvfs', 'f_frsize', define='HAVE_FRSIZE', headers='sys/statvfs.h')
>
> diff --git a/source3/include/local.h b/source3/include/local.h
> index 7f97d4ece9c..c2be1ff3b7f 100644
> --- a/source3/include/local.h
> +++ b/source3/include/local.h
> @@ -172,9 +172,6 @@
> /* Number in seconds for winbindd to wait for the mutex. Make this 2 * smbd wait time. */
> #define WINBIND_SERVER_MUTEX_WAIT_TIME (( ((NUM_CLI_AUTH_CONNECT_RETRIES) * ((CLI_AUTH_TIMEOUT)/1000)) + 5)*2)
>
> -/* Buffer size to use when printing backtraces */
> -#define BACKTRACE_STACK_SIZE 64
> -
> /* size of listen() backlog in smbd */
> #define SMBD_LISTEN_BACKLOG 50
>
> diff --git a/source3/include/proto.h b/source3/include/proto.h
> index fa87407ff24..2bc5ab2f532 100644
> --- a/source3/include/proto.h
> +++ b/source3/include/proto.h
> @@ -356,7 +356,6 @@ char *gidtoname(gid_t gid);
> uid_t nametouid(const char *name);
> gid_t nametogid(const char *name);
> void smb_panic_s3(const char *why);
> -void log_stack_trace(void);
> const char *readdirname(DIR *p);
> bool is_in_path(const char *name, name_compare_entry *namelist, bool case_sensitive);
> void set_namearray(name_compare_entry **ppname_array, const char *namelist);
> diff --git a/source3/lib/util.c b/source3/lib/util.c
> index 98c47b3df9f..5f786f95d3e 100644
> --- a/source3/lib/util.c
> +++ b/source3/lib/util.c
> @@ -839,103 +839,6 @@ void smb_panic_s3(const char *why)
> }
>
> /*******************************************************************
> - Print a backtrace of the stack to the debug log. This function
> - DELIBERATELY LEAKS MEMORY. The expectation is that you should
> - exit shortly after calling it.
> -********************************************************************/
> -
> -#ifdef HAVE_LIBUNWIND_H
> -#include <libunwind.h>
> -#endif
> -
> -#ifdef HAVE_EXECINFO_H
> -#include <execinfo.h>
> -#endif
> -
> -void log_stack_trace(void)
> -{
> -#ifdef HAVE_LIBUNWIND
> - /* Try to use libunwind before any other technique since on ia64
> - * libunwind correctly walks the stack in more circumstances than
> - * backtrace.
> - */
> - unw_cursor_t cursor;
> - unw_context_t uc;
> - unsigned i = 0;
> -
> - char procname[256];
> - unw_word_t ip, sp, off;
> -
> - procname[sizeof(procname) - 1] = '\0';
> -
> - if (unw_getcontext(&uc) != 0) {
> - goto libunwind_failed;
> - }
> -
> - if (unw_init_local(&cursor, &uc) != 0) {
> - goto libunwind_failed;
> - }
> -
> - DEBUG(0, ("BACKTRACE:\n"));
> -
> - do {
> - ip = sp = 0;
> - unw_get_reg(&cursor, UNW_REG_IP, &ip);
> - unw_get_reg(&cursor, UNW_REG_SP, &sp);
> -
> - switch (unw_get_proc_name(&cursor,
> - procname, sizeof(procname) - 1, &off) ) {
> - case 0:
> - /* Name found. */
> - case -UNW_ENOMEM:
> - /* Name truncated. */
> - DEBUGADD(0, (" #%u %s + %#llx [ip=%#llx] [sp=%#llx]\n",
> - i, procname, (long long)off,
> - (long long)ip, (long long) sp));
> - break;
> - default:
> - /* case -UNW_ENOINFO: */
> - /* case -UNW_EUNSPEC: */
> - /* No symbol name found. */
> - DEBUGADD(0, (" #%u %s [ip=%#llx] [sp=%#llx]\n",
> - i, "<unknown symbol>",
> - (long long)ip, (long long) sp));
> - }
> - ++i;
> - } while (unw_step(&cursor) > 0);
> -
> - return;
> -
> -libunwind_failed:
> - DEBUG(0, ("unable to produce a stack trace with libunwind\n"));
> -
> -#elif HAVE_BACKTRACE_SYMBOLS
> - void *backtrace_stack[BACKTRACE_STACK_SIZE];
> - size_t backtrace_size;
> - char **backtrace_strings;
> -
> - /* get the backtrace (stack frames) */
> - backtrace_size = backtrace(backtrace_stack,BACKTRACE_STACK_SIZE);
> - backtrace_strings = backtrace_symbols(backtrace_stack, backtrace_size);
> -
> - DEBUG(0, ("BACKTRACE: %lu stack frames:\n",
> - (unsigned long)backtrace_size));
> -
> - if (backtrace_strings) {
> - int i;
> -
> - for (i = 0; i < backtrace_size; i++)
> - DEBUGADD(0, (" #%u %s\n", i, backtrace_strings[i]));
> -
> - /* Leak the backtrace_strings, rather than risk what free() might do */
> - }
> -
> -#else
> - DEBUG(0, ("unable to produce a stack trace on this platform\n"));
> -#endif
> -}
> -
> -/*******************************************************************
> A readdir wrapper which just returns the file name.
> ********************************************************************/
>
> diff --git a/source3/wscript b/source3/wscript
> index 8d658b2f53e..ab64e80214e 100644
> --- a/source3/wscript
> +++ b/source3/wscript
> @@ -96,7 +96,7 @@ def configure(conf):
> # We crash without vfs_default
> required_static_modules.extend(TO_LIST('vfs_default'))
>
> - conf.CHECK_HEADERS('execinfo.h libunwind.h netdb.h')
> + conf.CHECK_HEADERS('netdb.h')
> conf.CHECK_HEADERS('linux/falloc.h linux/ioctl.h')
>
> conf.CHECK_FUNCS('getcwd fchown chmod fchmod mknod')
> --
> 2.11.0
>
>
> From 19dba766ad65916fe329db77f6bdd8dc59d882a2 Mon Sep 17 00:00:00 2001
> From: Andrew Bartlett <abartlet at samba.org>
> Date: Tue, 10 Apr 2018 16:37:45 +1200
> Subject: [PATCH 4/4] lib/util: Call log_stack_trace() in smb_panic_default()
>
> This matches the AD DC with the behaviour in smbd.
>
> Signed-off-by: Andrew Bartlett <abartlet at samba.org>
> ---
> lib/util/fault.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/lib/util/fault.c b/lib/util/fault.c
> index af06c9484db..77415e1134d 100644
> --- a/lib/util/fault.c
> +++ b/lib/util/fault.c
> @@ -126,6 +126,7 @@ static void smb_panic_default(const char *why)
> {
> DEBUG(0,("PANIC (pid %llu): %s\n",
> (unsigned long long)getpid(), why));
> + log_stack_trace();
>
> #if defined(HAVE_PRCTL) && defined(PR_SET_PTRACER)
> /*
> --
> 2.11.0
>
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