From: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
To: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Igor Lubashev <ilubashe@akamai.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jiri Olsa <jolsa@redhat.com>,
Alexey Budankov <alexey.budankov@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
James Morris <jmorris@namei.org>
Subject: Re: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
Date: Wed, 14 Aug 2019 15:48:14 -0300 [thread overview]
Message-ID: <20190814184814.GM9280@kernel.org> (raw)
In-Reply-To: <CANLsYkxZE0CQJKQ-bFi=zFV5vTCbL2v76+x1fmCpqNruqWiFXg@mail.gmail.com>
Em Wed, Aug 14, 2019 at 12:04:33PM -0600, Mathieu Poirier escreveu:
> On Wed, 7 Aug 2019 at 08:44, Igor Lubashev <ilubashe@akamai.com> wrote:
> >
> > Kernel is using CAP_SYSLOG capability instead of uid==0 and euid==0 when
> > checking kptr_restrict. Make perf do the same.
> >
> > Also, the kernel is a more restrictive than "no restrictions" in case of
> > kptr_restrict==0, so add the same logic to perf.
> >
> > Signed-off-by: Igor Lubashev <ilubashe@akamai.com>
> > ---
> > tools/perf/util/symbol.c | 15 +++++++++++----
> > 1 file changed, 11 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> > index 173f3378aaa0..046271103499 100644
> > --- a/tools/perf/util/symbol.c
> > +++ b/tools/perf/util/symbol.c
> > @@ -4,6 +4,7 @@
> > #include <stdlib.h>
> > #include <stdio.h>
> > #include <string.h>
> > +#include <linux/capability.h>
> > #include <linux/kernel.h>
> > #include <linux/mman.h>
> > #include <linux/time64.h>
> > @@ -15,8 +16,10 @@
> > #include <inttypes.h>
> > #include "annotate.h"
> > #include "build-id.h"
> > +#include "cap.h"
> > #include "util.h"
> > #include "debug.h"
> > +#include "event.h"
> > #include "machine.h"
> > #include "map.h"
> > #include "symbol.h"
> > @@ -890,7 +893,11 @@ bool symbol__restricted_filename(const char *filename,
> > {
> > bool restricted = false;
> >
> > - if (symbol_conf.kptr_restrict) {
> > + /* Per kernel/kallsyms.c:
> > + * we also restrict when perf_event_paranoid > 1 w/o CAP_SYSLOG
> > + */
> > + if (symbol_conf.kptr_restrict ||
> > + (perf_event_paranoid() > 1 && !perf_cap__capable(CAP_SYSLOG))) {
> > char *r = realpath(filename, NULL);
> >
>
> # echo 0 > /proc/sys/kernel/kptr_restrict
> # ./tools/perf/perf record -e instructions:k uname
> perf: Segmentation fault
> Obtained 10 stack frames.
> ./tools/perf/perf(sighandler_dump_stack+0x44) [0x55af9e5da5d4]
> /lib/x86_64-linux-gnu/libc.so.6(+0x3ef20) [0x7fd31efb6f20]
> ./tools/perf/perf(perf_event__synthesize_kernel_mmap+0xa7) [0x55af9e590337]
> ./tools/perf/perf(+0x1cf5be) [0x55af9e50c5be]
> ./tools/perf/perf(cmd_record+0x1022) [0x55af9e50dff2]
> ./tools/perf/perf(+0x23f98d) [0x55af9e57c98d]
> ./tools/perf/perf(+0x23fc9e) [0x55af9e57cc9e]
> ./tools/perf/perf(main+0x369) [0x55af9e4f6bc9]
> /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe7) [0x7fd31ef99b97]
> ./tools/perf/perf(_start+0x2a) [0x55af9e4f704a]
> Segmentation fault
>
> I can reproduce this on both x86 and ARM64.
I don't see this with these two csets removed:
7ff5b5911144 perf symbols: Use CAP_SYSLOG with kptr_restrict checks
d7604b66102e perf tools: Use CAP_SYS_ADMIN with perf_event_paranoid checks
Which were the ones I guessed were related to the problem you reported,
so they are out of my ongoing perf/core pull request to Ingo/Thomas, now
trying with these applied and your instructions...
- Arnaldo
next prev parent reply other threads:[~2019-08-14 18:48 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 14:44 [PATCH v3 0/4] perf: Use capabilities instead of uid and euid Igor Lubashev
2019-08-07 14:44 ` [PATCH v3 1/4] perf: Add capability-related utilities Igor Lubashev
2019-08-12 19:43 ` Arnaldo Carvalho de Melo
2019-08-15 9:24 ` [tip:perf/core] tools build: Add capability-related feature detection tip-bot for Igor Lubashev
2019-08-15 9:25 ` [tip:perf/core] perf tools: Add helpers to use capabilities if present tip-bot for Igor Lubashev
2019-08-07 14:44 ` [PATCH v3 2/4] perf: Use CAP_SYS_ADMIN with perf_event_paranoid checks Igor Lubashev
2019-08-12 20:01 ` Arnaldo Carvalho de Melo
2019-08-12 20:15 ` Arnaldo Carvalho de Melo
2019-08-12 22:33 ` Lubashev, Igor
2019-08-13 13:20 ` Arnaldo Carvalho de Melo
2019-08-07 14:44 ` [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks Igor Lubashev
2019-08-14 18:04 ` Mathieu Poirier
2019-08-14 18:48 ` Arnaldo Carvalho de Melo [this message]
2019-08-14 18:52 ` Arnaldo Carvalho de Melo
2019-08-14 20:02 ` Lubashev, Igor
2019-08-15 15:01 ` Mathieu Poirier
2019-08-15 20:16 ` Mathieu Poirier
2019-08-15 21:42 ` Arnaldo Carvalho de Melo
2019-08-19 16:51 ` Mathieu Poirier
2019-08-19 22:22 ` Lubashev, Igor
2019-08-20 16:57 ` Mathieu Poirier
2019-08-20 17:13 ` Arnaldo Carvalho de Melo
2019-08-27 1:58 ` Lubashev, Igor
2019-08-15 22:27 ` Lubashev, Igor
2019-08-07 14:44 ` [PATCH v3 4/4] perf: Use CAP_SYS_ADMIN instead of euid==0 with ftrace Igor Lubashev
2019-08-12 20:22 ` Arnaldo Carvalho de Melo
2019-08-12 20:27 ` Arnaldo Carvalho de Melo
2019-08-12 20:29 ` Arnaldo Carvalho de Melo
2019-08-12 21:42 ` Mathieu Poirier
2019-08-13 13:23 ` Arnaldo Carvalho de Melo
2019-08-13 16:35 ` Mathieu Poirier
2019-08-15 9:27 ` [tip:perf/core] perf ftrace: Use CAP_SYS_ADMIN instead of euid==0 tip-bot for Igor Lubashev
2019-08-12 9:13 ` [PATCH v3 0/4] perf: Use capabilities instead of uid and euid Jiri Olsa
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