Re: [PATCH] perf tools: Fix mode setting in copyfile_mode_ns()

[Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>]

Em Mon, Oct 07, 2019 at 12:47:47PM +0200, Jiri Olsa escreveu:
> On Mon, Oct 07, 2019 at 10:02:21AM +0300, Adrian Hunter wrote:
> > slow_copyfile() opens the file by name, so "write" permissions must not
> > be removed in copyfile_mode_ns() before calling slow_copyfile().
> > 
> > Example:
> > 
> >  Before:
> >   $ sudo chmod +r /proc/kcore
> >   $ sudo setcap "cap_sys_admin,cap_sys_ptrace,cap_syslog,cap_sys_rawio=ep" tools/perf/perf
> >   $ tools/perf/perf buildid-cache -k /proc/kcore
> >   Couldn't add /proc/kcore
> > 
> >  After:
> >   $ sudo chmod +r /proc/kcore
> >   $ sudo setcap "cap_sys_admin,cap_sys_ptrace,cap_syslog,cap_sys_rawio=ep" tools/perf/perf
> >   $ tools/perf/perf buildid-cache -v -k /proc/kcore
> >   kcore added to build-id cache directory /home/ahunter/.debug/[kernel.kcore]/37e340b1b5a7cf4f57ba8de2bc777359588a957f/2019100709562289
> > 
> > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> 
> Acked-by: Jiri Olsa <jolsa@kernel.org>

Thanks, applied to perf/urgent.

- Arnaldo
 
> thanks,
> jirka
> 
> > ---
> >  tools/perf/util/copyfile.c | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> > 
> > diff --git a/tools/perf/util/copyfile.c b/tools/perf/util/copyfile.c
> > index 3fa0db136667..47e03de7c235 100644
> > --- a/tools/perf/util/copyfile.c
> > +++ b/tools/perf/util/copyfile.c
> > @@ -101,14 +101,16 @@ static int copyfile_mode_ns(const char *from, const char *to, mode_t mode,
> >  	if (tofd < 0)
> >  		goto out;
> >  
> > -	if (fchmod(tofd, mode))
> > -		goto out_close_to;
> > -
> >  	if (st.st_size == 0) { /* /proc? do it slowly... */
> >  		err = slow_copyfile(from, tmp, nsi);
> > +		if (!err && fchmod(tofd, mode))
> > +			err = -1;
> >  		goto out_close_to;
> >  	}
> >  
> > +	if (fchmod(tofd, mode))
> > +		goto out_close_to;
> > +
> >  	nsinfo__mountns_enter(nsi, &nsc);
> >  	fromfd = open(from, O_RDONLY);
> >  	nsinfo__mountns_exit(&nsc);
> > -- 
> > 2.17.1
> > 

-- 

- Arnaldo