linux-kernel - Re: [PATCH] tracing/x86: Update syscall trace events to handle new x86 syscall func names

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 17 Apr 2018 12:39:27 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Dominik Brodowski <linux@...inikbrodowski.net>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: [PATCH] tracing/x86: Update syscall trace events to handle new
 x86 syscall func names

On Tue, 17 Apr 2018 18:10:29 +0200
Dominik Brodowski <linux@...inikbrodowski.net> wrote:


> > Because the x86 system calls had "__x86_" appended to the "sys" for the  
> 
> __x64 actually.

Heh, I constantly make that mistake.

Hmm, OK, I need to look at this a bit more. If this is x64, then
there's probably syscalls (on 32 bit), that don't have that. It should
probably include more checks. Something like:

  return !strcmp(sym + 9, name + 3) || !strcmp(sym + 3, name + 3);


> 
> > names, they do not match the default compare algorithm. As this was a
> > problem for power pc, the algorithm can be overwritten by the architecture.
> > The solution is to have x86 have its own algorithm to do the compare and
> > this brings back the system call trace events.  
> 
> this lets me wonder *which* syscall "function" should be included in this
> directory. Is it really the stub (__x64_sys_waitid, for example), or better
> the sign-extending C function (__se_sys_waitid) which then calls an
> internal helper (__do_sys_waitid). An additional advantage:
> __se_sys_waitid would be available on x86 and, AFAICS, on all other archs.

It should include anything that uses the "SYSCALL_DEFINE#()" macros.

> 
> > Reported-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> > Fixes: d5a00528b58c ("syscalls/core, syscalls/x86: Rename struct pt_regs-based sys_*() to __x64_sys_*()")
> > Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
> > ---
> >  arch/x86/include/asm/ftrace.h | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> > 
> > diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
> > index 09ad88572746..c30b3fac20ae 100644
> > --- a/arch/x86/include/asm/ftrace.h
> > +++ b/arch/x86/include/asm/ftrace.h
> > @@ -31,6 +31,16 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
> >  	return addr;
> >  }
> >  
> > +#define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
> > +static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
> > +{
> > +	/*
> > +	 * Compare the symbol name with the system call name. Skip the
> > +	 * "__x64_sys" prefix.
> > +	 */
> > +	return !strcmp(sym + 9, name + 3);
> > +}  
> 
> What are the first three chars you skip for *name?

"sys_"

-- Steve

> 
> Thanks,
> 	Dominik