RE: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
On Tue, August 20, 2019 at 1:14 PM Arnaldo Carvalho de Melo wrote: > > Arnaldo, once we decide what the right fix is, I am happy to post the > update (options 1, 1+2) as a patch series. > > I think you should get the checks for ref_reloc_sym in place so as to make the > code overall more robust, and also go on continuing to make the checks in > tools/perf/ to match what is checked on the other side of the mirror, i.e. by > the kernel, so from a quick read, please put first the robustness patches > (check ref_reloc_sym) do your other suggestions and update the warnings, > then refresh the two patches that still are not in my perf/core branch: > > [acme@quaco perf]$ git rebase perf/core > First, rewinding head to replay your work on top of it... > Applying: perf tools: Use CAP_SYS_ADMIN with perf_event_paranoid checks > Applying: perf symbols: Use CAP_SYSLOG with kptr_restrict checks > [acme@quaco perf]$ > > I've pushed out perf/cap, so you can go from there as it is rebased on my > current perf/core. > > Then test all these cases: with/without libcap, with euid==0 and different > than zero, with capabilities, etc, patch by patch so that we don't break > bisection nor regress, All done. I've posted the update as a new follow-up series: https://lkml.kernel.org/lkml/1566869956-7154-1-git-send-email-iluba...@akamai.com/ rebased on your perf/core. I've tested 336 permutations (see the new cover). In particular, I was able to reproduce the crash on perf/cap and confirm that no permutation can cause such crashes for any of the patches in the series. > Thanks and keep up the good work! > > - Arnaldo - Igor
Re: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
Em Mon, Aug 19, 2019 at 10:22:07PM +, Lubashev, Igor escreveu: > On Mon, August 19, 2019 at 12:51 PM Mathieu Poirier > wrote: > > On Thu, 15 Aug 2019 at 15:42, Arnaldo Carvalho de Melo > > wrote: > > Things are working properly on your perf/cap branch. I tested with on both > > x86 and ARM. > Mathieu, you are probably testing with euid==0. If you were to test > with euid!=0 but with CAP_SYSLOG and no libcap (and kptr_restrict=0, > perf_event_paranoid=2), you would likely hit the bug that you > identified in __perf_event__synthesize_kermel_mmap(). > See > https://lkml.kernel.org/lkml/930a59730c0d495f8c5acf4f99048...@usma1ex-dag1mb6.msg.corp.akamai.com > for the fix (Option 1 only or Options 1+2). > > Arnaldo, once we decide what the right fix is, I am happy to post the update > (options 1, 1+2) as a patch series. I think you should get the checks for ref_reloc_sym in place so as to make the code overall more robust, and also go on continuing to make the checks in tools/perf/ to match what is checked on the other side of the mirror, i.e. by the kernel, so from a quick read, please put first the robustness patches (check ref_reloc_sym) do your other suggestions and update the warnings, then refresh the two patches that still are not in my perf/core branch: [acme@quaco perf]$ git rebase perf/core First, rewinding head to replay your work on top of it... Applying: perf tools: Use CAP_SYS_ADMIN with perf_event_paranoid checks Applying: perf symbols: Use CAP_SYSLOG with kptr_restrict checks [acme@quaco perf]$ I've pushed out perf/cap, so you can go from there as it is rebased on my current perf/core. Then test all these cases: with/without libcap, with euid==0 and different than zero, with capabilities, etc, patch by patch so that we don't break bisection nor regress, Thanks and keep up the good work! - Arnaldo > - Igor > > > > > > I am not sure how this can be fixed. I counted a total of 19 > > > > instances where kmap->ref_reloc_sym->XYZ is called, only 2 of wich > > > > care to check if kmap->ref_reloc_sym is valid before proceeding. As > > > > such I must hope that in the 17 other cases, kmap->ref_reloc_sym is > > > > guaranteed to be valid. If I am correct then all we need is to > > > > check for a valid pointer in _perf_event__synthesize_kernel_mmap(). > > > > Otherwise it will be a little harder. > > > > > > > > Mathieu > -- - Arnaldo
Re: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
On Mon, 19 Aug 2019 at 16:22, Lubashev, Igor wrote: > > On Mon, August 19, 2019 at 12:51 PM Mathieu Poirier > wrote: > > On Thu, 15 Aug 2019 at 15:42, Arnaldo Carvalho de Melo > > wrote: > > > > > > Em Thu, Aug 15, 2019 at 02:16:48PM -0600, Mathieu Poirier escreveu: > > > > On Wed, 14 Aug 2019 at 14:02, Lubashev, Igor > > wrote: > > > > > > > > > > > On Wed, August 14, 2019 at 2:52 PM Arnaldo Carvalho de Melo > > wrote: > > > > > > Em Wed, Aug 14, 2019 at 03:48:14PM -0300, Arnaldo Carvalho de > > > > > > Melo > > > > > > escreveu: > > > > > > > Em Wed, Aug 14, 2019 at 12:04:33PM -0600, Mathieu Poirier > > escreveu: > > > > > > > > # 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... > > > > > > > > > > > > Can't repro: > > > > > > > > > > > > [root@quaco ~]# cat /proc/sys/kernel/kptr_restrict > > > > > > 0 > > > > > > [root@quaco ~]# perf record -e instructions:k uname Linux [ perf > > record: > > > > > > Woken up 1 times to write data ] [ perf record: Captured and > > > > > > wrote 0.024 MB perf.data (1 samples) ] [root@quaco ~]# echo 1 > > > > > > > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e > > > > > > instructions:k uname Linux [ perf record: Woken up 1 times to write > > data ] [ perf record: > > > > > > Captured and wrote 0.024 MB perf.data (1 samples) ] [root@quaco > > > > > > ~]# echo > > > > > > 0 > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record > > > > > > -e instructions:k uname Linux [ perf record: Woken up 1 times to > > > > > > write data ] [ perf record: Captured and wrote 0.024 MB > > > > > > perf.data (1 samples) ] [root@quaco ~]# > > > > > > > > > > > > [acme@quaco perf]$ git log --oneline --author Lubashev tools/ > > > > > > 7ff5b5911144 (HEAD -> perf/cap, acme.korg/tmp.perf/cap, > > > > > > acme.korg/perf/cap) perf symbols: Use CAP_SYSLOG with > > > > > > kptr_restrict checks d7604b66102e perf tools: Use CAP_SYS_ADMIN > > > > > > with perf_event_paranoid checks c766f3df635d perf ftrace: Use > > > > > > CAP_SYS_ADMIN instead of euid==0 c22e150e3afa perf tools: Add > > > > > > helpers to use capabilities if present > > > > > > 74d5f3d06f70 tools build: Add capability-related feature > > > > > > detection perf version 5.3.rc4.g7ff5b5911144 [acme@quaco perf]$ > > > > > > > > > > I got an ARM64 cloud VM, but I cannot reproduce. > > > > > # cat /proc/sys/kernel/kptr_restrict > > > > > 0 > > > > > > > > > > Perf trace works fine (does not die): > > > > > # ./perf trace -a > > > > > > > > > > Here is my setup: > > > > > Repo: git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git > > > > > Branch: tmp.perf/cap > > > > > Commit: 7ff5b5911 "perf symbols: Use CAP_SYSLOG with kptr_restrict > > checks" > > > > > gcc --version: gcc (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1) 7.4.0 > > > > > uname -a: Linux arm-4-par-1 4.9.93-mainline-rev1 #1 SMP Tue Apr 10 > > > > > 09:54:46 UTC 2018 aarch64 aarch64 aarch64 GNU/Linux lsb_release > > > > > -a: Ubuntu 18.04.3 LTS > > > > > > > > > > Auto-detecting system features: > > > > > ... dwarf: [ on ] > > > > > ...dwarf_getlocations: [ on ] > > > > > ... glibc: [ on ] > > > > > ... gtk2: [ on ] > > > > > ... libaudit: [ on ] > > > > > ...libbfd: [ on ] > > > > > ...libcap: [ on ] > > > > > ...libelf: [ on ] > > > > > ...
RE: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
On Mon, August 19, 2019 at 12:51 PM Mathieu Poirier wrote: > On Thu, 15 Aug 2019 at 15:42, Arnaldo Carvalho de Melo > wrote: > > > > Em Thu, Aug 15, 2019 at 02:16:48PM -0600, Mathieu Poirier escreveu: > > > On Wed, 14 Aug 2019 at 14:02, Lubashev, Igor > wrote: > > > > > > > > > On Wed, August 14, 2019 at 2:52 PM Arnaldo Carvalho de Melo > wrote: > > > > > Em Wed, Aug 14, 2019 at 03:48:14PM -0300, Arnaldo Carvalho de > > > > > Melo > > > > > escreveu: > > > > > > Em Wed, Aug 14, 2019 at 12:04:33PM -0600, Mathieu Poirier > escreveu: > > > > > > > # 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... > > > > > > > > > > Can't repro: > > > > > > > > > > [root@quaco ~]# cat /proc/sys/kernel/kptr_restrict > > > > > 0 > > > > > [root@quaco ~]# perf record -e instructions:k uname Linux [ perf > record: > > > > > Woken up 1 times to write data ] [ perf record: Captured and > > > > > wrote 0.024 MB perf.data (1 samples) ] [root@quaco ~]# echo 1 > > > > > > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e > > > > > instructions:k uname Linux [ perf record: Woken up 1 times to write > data ] [ perf record: > > > > > Captured and wrote 0.024 MB perf.data (1 samples) ] [root@quaco > > > > > ~]# echo > > > > > 0 > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record > > > > > -e instructions:k uname Linux [ perf record: Woken up 1 times to > > > > > write data ] [ perf record: Captured and wrote 0.024 MB > > > > > perf.data (1 samples) ] [root@quaco ~]# > > > > > > > > > > [acme@quaco perf]$ git log --oneline --author Lubashev tools/ > > > > > 7ff5b5911144 (HEAD -> perf/cap, acme.korg/tmp.perf/cap, > > > > > acme.korg/perf/cap) perf symbols: Use CAP_SYSLOG with > > > > > kptr_restrict checks d7604b66102e perf tools: Use CAP_SYS_ADMIN > > > > > with perf_event_paranoid checks c766f3df635d perf ftrace: Use > > > > > CAP_SYS_ADMIN instead of euid==0 c22e150e3afa perf tools: Add > > > > > helpers to use capabilities if present > > > > > 74d5f3d06f70 tools build: Add capability-related feature > > > > > detection perf version 5.3.rc4.g7ff5b5911144 [acme@quaco perf]$ > > > > > > > > I got an ARM64 cloud VM, but I cannot reproduce. > > > > # cat /proc/sys/kernel/kptr_restrict > > > > 0 > > > > > > > > Perf trace works fine (does not die): > > > > # ./perf trace -a > > > > > > > > Here is my setup: > > > > Repo: git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git > > > > Branch: tmp.perf/cap > > > > Commit: 7ff5b5911 "perf symbols: Use CAP_SYSLOG with kptr_restrict > checks" > > > > gcc --version: gcc (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1) 7.4.0 > > > > uname -a: Linux arm-4-par-1 4.9.93-mainline-rev1 #1 SMP Tue Apr 10 > > > > 09:54:46 UTC 2018 aarch64 aarch64 aarch64 GNU/Linux lsb_release > > > > -a: Ubuntu 18.04.3 LTS > > > > > > > > Auto-detecting system features: > > > > ... dwarf: [ on ] > > > > ...dwarf_getlocations: [ on ] > > > > ... glibc: [ on ] > > > > ... gtk2: [ on ] > > > > ... libaudit: [ on ] > > > > ...libbfd: [ on ] > > > > ...libcap: [ on ] > > > > ...libelf: [ on ] > > > > ... libnuma: [ on ] > > > > ...numa_num_possible_cpus: [ on ] > > > > ... libperl: [ on ] > > > > ... libpython: [ on ] > > > > ... libcrypto: [ on ] > > > > ...
Re: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
On Thu, 15 Aug 2019 at 15:42, Arnaldo Carvalho de Melo wrote: > > Em Thu, Aug 15, 2019 at 02:16:48PM -0600, Mathieu Poirier escreveu: > > On Wed, 14 Aug 2019 at 14:02, Lubashev, Igor wrote: > > > > > > > On Wed, August 14, 2019 at 2:52 PM Arnaldo Carvalho de Melo > > > > wrote: > > > > Em Wed, Aug 14, 2019 at 03:48:14PM -0300, Arnaldo Carvalho de Melo > > > > escreveu: > > > > > Em Wed, Aug 14, 2019 at 12:04:33PM -0600, Mathieu Poirier escreveu: > > > > > > # 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... > > > > > > > > Can't repro: > > > > > > > > [root@quaco ~]# cat /proc/sys/kernel/kptr_restrict > > > > 0 > > > > [root@quaco ~]# perf record -e instructions:k uname Linux [ perf record: > > > > Woken up 1 times to write data ] [ perf record: Captured and wrote > > > > 0.024 MB > > > > perf.data (1 samples) ] [root@quaco ~]# echo 1 > > > > > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e > > > > instructions:k > > > > uname Linux [ perf record: Woken up 1 times to write data ] [ perf > > > > record: > > > > Captured and wrote 0.024 MB perf.data (1 samples) ] [root@quaco ~]# echo > > > > 0 > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e > > > > instructions:k uname Linux [ perf record: Woken up 1 times to write > > > > data ] [ > > > > perf record: Captured and wrote 0.024 MB perf.data (1 samples) ] > > > > [root@quaco ~]# > > > > > > > > [acme@quaco perf]$ git log --oneline --author Lubashev tools/ > > > > 7ff5b5911144 (HEAD -> perf/cap, acme.korg/tmp.perf/cap, > > > > acme.korg/perf/cap) perf symbols: Use CAP_SYSLOG with kptr_restrict > > > > checks d7604b66102e perf tools: Use CAP_SYS_ADMIN with > > > > perf_event_paranoid checks c766f3df635d perf ftrace: Use CAP_SYS_ADMIN > > > > instead of euid==0 c22e150e3afa perf tools: Add helpers to use > > > > capabilities if > > > > present > > > > 74d5f3d06f70 tools build: Add capability-related feature detection perf > > > > version 5.3.rc4.g7ff5b5911144 [acme@quaco perf]$ > > > > > > I got an ARM64 cloud VM, but I cannot reproduce. > > > # cat /proc/sys/kernel/kptr_restrict > > > 0 > > > > > > Perf trace works fine (does not die): > > > # ./perf trace -a > > > > > > Here is my setup: > > > Repo: git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git > > > Branch: tmp.perf/cap > > > Commit: 7ff5b5911 "perf symbols: Use CAP_SYSLOG with kptr_restrict checks" > > > gcc --version: gcc (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1) 7.4.0 > > > uname -a: Linux arm-4-par-1 4.9.93-mainline-rev1 #1 SMP Tue Apr 10 > > > 09:54:46 UTC 2018 aarch64 aarch64 aarch64 GNU/Linux > > > lsb_release -a: Ubuntu 18.04.3 LTS > > > > > > Auto-detecting system features: > > > ... dwarf: [ on ] > > > ...dwarf_getlocations: [ on ] > > > ... glibc: [ on ] > > > ... gtk2: [ on ] > > > ... libaudit: [ on ] > > > ...libbfd: [ on ] > > > ...libcap: [ on ] > > > ...libelf: [ on ] > > > ... libnuma: [ on ] > > > ...numa_num_possible_cpus: [ on ] > > > ... libperl: [ on ] > > > ... libpython: [ on ] > > > ... libcrypto: [ on ] > > > ... libunwind: [ on ] > > > ...libdw-dwarf-unwind: [ on ] > > > ... zlib: [ on ] > > > ... lzma: [ on ] > > > ... get_cpuid: [ OFF ] > > > ...
RE: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
On Thu, August 15, 2019 at 4:17 PM Mathieu Poirier
wrote:
> On Wed, 14 Aug 2019 at 14:02, Lubashev, Igor
> wrote:
> >
> > > On Wed, August 14, 2019 at 2:52 PM Arnaldo Carvalho de Melo
> wrote:
> > > Em Wed, Aug 14, 2019 at 03:48:14PM -0300, Arnaldo Carvalho de Melo
> > > escreveu:
> > > > Em Wed, Aug 14, 2019 at 12:04:33PM -0600, Mathieu Poirier escreveu:
> > > > > # 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...
SNIP
> I isolated the problem to libcap-dev - if it is not installed a segmentation
> fault
> will occur. Since this set is about using capabilities it is obvious that not
> having it on a system should fail a trace session, but it should not crash it.
>
> If libcap-dev is not installed function symbol__restricted_filename() will
> return true, which in turn will prevent symbol_name to be set in
> machine__get_running_kernel_start(). That prevents function
> map__set_kallsyms_ref_reloc_sym() from being called in
> machine__create_kernel_maps(), resulting in kmap->ref_reloc_sym being
> NULL in _perf_event__synthesize_kernel_mmap() and a segmentation fault.
Thank you, great find.
> I am not sure how this can be fixed. I counted a total of 19 instances where
> kmap->ref_reloc_sym->XYZ is called, only 2 of wich care to check if kmap-
> >ref_reloc_sym is valid before proceeding. As such I must hope that in the
> 17 other cases, kmap->ref_reloc_sym is guaranteed to be valid. If I am
> correct then all we need is to check for a valid pointer in
> _perf_event__synthesize_kernel_mmap().
> Otherwise it will be a little harder.
I also see 19 instances in 5 files, but by my inspection all cases but one are
ok (the code checks for NULL earlier in the function or in a helper function).
The not ok case is __perf_event__synthesize_kermel_mmap(), which simply checks
symbol_conf.kptr_restrict.
Option 1 =
Fix __perf_event__synthesize_kermel_mmap(). This probably should be done
regardless.
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index f440fdc3e953..b84f5f3c9651 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -913,11 +913,13 @@ static int __perf_event__synthesize_kernel_mmap(struct
perf_tool *tool,
int err;
union perf_event *event;
- if (symbol_conf.kptr_restrict)
- return -1;
if (map == NULL)
return -1;
+ kmap = map__kmap(map);
+ if (!kmap->ref_reloc_sym)
+ return -1;
+
/*
* We should get this from /sys/kernel/sections/.text, but till that is
* available use this, and after it is use this as a fallback for older
@@ -940,7 +942,6 @@ static int __perf_event__synthesize_kernel_mmap(struct
perf_tool *tool,
event->header.misc = PERF_RECORD_MISC_GUEST_KERNEL;
}
- kmap = map__kmap(map);
size = snprintf(event->mmap.filename, sizeof(event->mmap.filename),
"%s%s", machine->mmap_name, kmap->ref_reloc_sym->name)
+ 1;
size = PERF_ALIGN(size, sizeof(u64));
--
Option 2 =
Move the new perf_event_paranoid() check from symbol__restricted_filename() to
symbol__read_kptr_restrict().
Other than the use above, kptr_restrict is only used for printing warnings.
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 7409d2facd5b..035f2e75728c 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -898,11 +898,7 @@ bool symbol__restricted_filename(const char *filename,
{
bool restricted = false;
- /* Per kernel/kallsyms.c:
-* we also restrict when perf_event_paranoid > 1 w/o CAP_
Re: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
Em Thu, Aug 15, 2019 at 02:16:48PM -0600, Mathieu Poirier escreveu: > On Wed, 14 Aug 2019 at 14:02, Lubashev, Igor wrote: > > > > > On Wed, August 14, 2019 at 2:52 PM Arnaldo Carvalho de Melo > > > wrote: > > > Em Wed, Aug 14, 2019 at 03:48:14PM -0300, Arnaldo Carvalho de Melo > > > escreveu: > > > > Em Wed, Aug 14, 2019 at 12:04:33PM -0600, Mathieu Poirier escreveu: > > > > > # 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... > > > > > > Can't repro: > > > > > > [root@quaco ~]# cat /proc/sys/kernel/kptr_restrict > > > 0 > > > [root@quaco ~]# perf record -e instructions:k uname Linux [ perf record: > > > Woken up 1 times to write data ] [ perf record: Captured and wrote 0.024 > > > MB > > > perf.data (1 samples) ] [root@quaco ~]# echo 1 > > > > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e > > > instructions:k > > > uname Linux [ perf record: Woken up 1 times to write data ] [ perf record: > > > Captured and wrote 0.024 MB perf.data (1 samples) ] [root@quaco ~]# echo > > > 0 > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e > > > instructions:k uname Linux [ perf record: Woken up 1 times to write data > > > ] [ > > > perf record: Captured and wrote 0.024 MB perf.data (1 samples) ] > > > [root@quaco ~]# > > > > > > [acme@quaco perf]$ git log --oneline --author Lubashev tools/ > > > 7ff5b5911144 (HEAD -> perf/cap, acme.korg/tmp.perf/cap, > > > acme.korg/perf/cap) perf symbols: Use CAP_SYSLOG with kptr_restrict > > > checks d7604b66102e perf tools: Use CAP_SYS_ADMIN with > > > perf_event_paranoid checks c766f3df635d perf ftrace: Use CAP_SYS_ADMIN > > > instead of euid==0 c22e150e3afa perf tools: Add helpers to use > > > capabilities if > > > present > > > 74d5f3d06f70 tools build: Add capability-related feature detection perf > > > version 5.3.rc4.g7ff5b5911144 [acme@quaco perf]$ > > > > I got an ARM64 cloud VM, but I cannot reproduce. > > # cat /proc/sys/kernel/kptr_restrict > > 0 > > > > Perf trace works fine (does not die): > > # ./perf trace -a > > > > Here is my setup: > > Repo: git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git > > Branch: tmp.perf/cap > > Commit: 7ff5b5911 "perf symbols: Use CAP_SYSLOG with kptr_restrict checks" > > gcc --version: gcc (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1) 7.4.0 > > uname -a: Linux arm-4-par-1 4.9.93-mainline-rev1 #1 SMP Tue Apr 10 09:54:46 > > UTC 2018 aarch64 aarch64 aarch64 GNU/Linux > > lsb_release -a: Ubuntu 18.04.3 LTS > > > > Auto-detecting system features: > > ... dwarf: [ on ] > > ...dwarf_getlocations: [ on ] > > ... glibc: [ on ] > > ... gtk2: [ on ] > > ... libaudit: [ on ] > > ...libbfd: [ on ] > > ...libcap: [ on ] > > ...libelf: [ on ] > > ... libnuma: [ on ] > > ...numa_num_possible_cpus: [ on ] > > ... libperl: [ on ] > > ... libpython: [ on ] > > ... libcrypto: [ on ] > > ... libunwind: [ on ] > > ...libdw-dwarf-unwind: [ on ] > > ... zlib: [ on ] > > ... lzma: [ on ] > > ... get_cpuid: [ OFF ] > > ... bpf: [ on ] > > ...libaio: [ on ] > > ... libzstd: [ on ] > > ...disassembler-four-args: [ on ] > > > > I also could not reproduce on x86: > > lsb_release -a: Ubuntu 18.04.1 LTS > > gcc --version: gcc (Ubuntu 7.4.0-1ub
Re: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
On Wed, 14 Aug 2019 at 14:02, Lubashev, Igor wrote: > > > On Wed, August 14, 2019 at 2:52 PM Arnaldo Carvalho de Melo > > wrote: > > Em Wed, Aug 14, 2019 at 03:48:14PM -0300, Arnaldo Carvalho de Melo > > escreveu: > > > Em Wed, Aug 14, 2019 at 12:04:33PM -0600, Mathieu Poirier escreveu: > > > > # 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... > > > > Can't repro: > > > > [root@quaco ~]# cat /proc/sys/kernel/kptr_restrict > > 0 > > [root@quaco ~]# perf record -e instructions:k uname Linux [ perf record: > > Woken up 1 times to write data ] [ perf record: Captured and wrote 0.024 MB > > perf.data (1 samples) ] [root@quaco ~]# echo 1 > > > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e instructions:k > > uname Linux [ perf record: Woken up 1 times to write data ] [ perf record: > > Captured and wrote 0.024 MB perf.data (1 samples) ] [root@quaco ~]# echo > > 0 > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e > > instructions:k uname Linux [ perf record: Woken up 1 times to write data ] [ > > perf record: Captured and wrote 0.024 MB perf.data (1 samples) ] > > [root@quaco ~]# > > > > [acme@quaco perf]$ git log --oneline --author Lubashev tools/ > > 7ff5b5911144 (HEAD -> perf/cap, acme.korg/tmp.perf/cap, > > acme.korg/perf/cap) perf symbols: Use CAP_SYSLOG with kptr_restrict > > checks d7604b66102e perf tools: Use CAP_SYS_ADMIN with > > perf_event_paranoid checks c766f3df635d perf ftrace: Use CAP_SYS_ADMIN > > instead of euid==0 c22e150e3afa perf tools: Add helpers to use capabilities > > if > > present > > 74d5f3d06f70 tools build: Add capability-related feature detection perf > > version 5.3.rc4.g7ff5b5911144 [acme@quaco perf]$ > > I got an ARM64 cloud VM, but I cannot reproduce. > # cat /proc/sys/kernel/kptr_restrict > 0 > > Perf trace works fine (does not die): > # ./perf trace -a > > Here is my setup: > Repo: git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git > Branch: tmp.perf/cap > Commit: 7ff5b5911 "perf symbols: Use CAP_SYSLOG with kptr_restrict checks" > gcc --version: gcc (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1) 7.4.0 > uname -a: Linux arm-4-par-1 4.9.93-mainline-rev1 #1 SMP Tue Apr 10 09:54:46 > UTC 2018 aarch64 aarch64 aarch64 GNU/Linux > lsb_release -a: Ubuntu 18.04.3 LTS > > Auto-detecting system features: > ... dwarf: [ on ] > ...dwarf_getlocations: [ on ] > ... glibc: [ on ] > ... gtk2: [ on ] > ... libaudit: [ on ] > ...libbfd: [ on ] > ...libcap: [ on ] > ...libelf: [ on ] > ... libnuma: [ on ] > ...numa_num_possible_cpus: [ on ] > ... libperl: [ on ] > ... libpython: [ on ] > ... libcrypto: [ on ] > ... libunwind: [ on ] > ...libdw-dwarf-unwind: [ on ] > ... zlib: [ on ] > ... lzma: [ on ] > ... get_cpuid: [ OFF ] > ... bpf: [ on ] > ...libaio: [ on ] > ... libzstd: [ on ] > ...disassembler-four-args: [ on ] > > I also could not reproduce on x86: > lsb_release -a: Ubuntu 18.04.1 LTS > gcc --version: gcc (Ubuntu 7.4.0-1ubuntu1~18.04aka10.0.0) 7.4.0 > uname -r: 4.4.0-154-generic I isolated the problem to libcap-dev - if it is not installed a segmentation fault will occur. Since this set is about using capabilities it is obvious that not having it on a system should fail a trace session, but it should not crash it.
Re: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
On Wed, 14 Aug 2019 at 14:02, Lubashev, Igor wrote: > > > On Wed, August 14, 2019 at 2:52 PM Arnaldo Carvalho de Melo > > wrote: > > Em Wed, Aug 14, 2019 at 03:48:14PM -0300, Arnaldo Carvalho de Melo > > escreveu: > > > Em Wed, Aug 14, 2019 at 12:04:33PM -0600, Mathieu Poirier escreveu: > > > > # 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... > > > > Can't repro: > > > > [root@quaco ~]# cat /proc/sys/kernel/kptr_restrict > > 0 > > [root@quaco ~]# perf record -e instructions:k uname Linux [ perf record: > > Woken up 1 times to write data ] [ perf record: Captured and wrote 0.024 MB > > perf.data (1 samples) ] [root@quaco ~]# echo 1 > > > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e instructions:k > > uname Linux [ perf record: Woken up 1 times to write data ] [ perf record: > > Captured and wrote 0.024 MB perf.data (1 samples) ] [root@quaco ~]# echo > > 0 > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e > > instructions:k uname Linux [ perf record: Woken up 1 times to write data ] [ > > perf record: Captured and wrote 0.024 MB perf.data (1 samples) ] > > [root@quaco ~]# > > > > [acme@quaco perf]$ git log --oneline --author Lubashev tools/ > > 7ff5b5911144 (HEAD -> perf/cap, acme.korg/tmp.perf/cap, > > acme.korg/perf/cap) perf symbols: Use CAP_SYSLOG with kptr_restrict > > checks d7604b66102e perf tools: Use CAP_SYS_ADMIN with > > perf_event_paranoid checks c766f3df635d perf ftrace: Use CAP_SYS_ADMIN > > instead of euid==0 c22e150e3afa perf tools: Add helpers to use capabilities > > if > > present > > 74d5f3d06f70 tools build: Add capability-related feature detection perf > > version 5.3.rc4.g7ff5b5911144 [acme@quaco perf]$ > > I got an ARM64 cloud VM, but I cannot reproduce. > # cat /proc/sys/kernel/kptr_restrict > 0 > > Perf trace works fine (does not die): > # ./perf trace -a > > Here is my setup: > Repo: git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git > Branch: tmp.perf/cap > Commit: 7ff5b5911 "perf symbols: Use CAP_SYSLOG with kptr_restrict checks" > gcc --version: gcc (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1) 7.4.0 > uname -a: Linux arm-4-par-1 4.9.93-mainline-rev1 #1 SMP Tue Apr 10 09:54:46 > UTC 2018 aarch64 aarch64 aarch64 GNU/Linux > lsb_release -a: Ubuntu 18.04.3 LTS > > Auto-detecting system features: > ... dwarf: [ on ] > ...dwarf_getlocations: [ on ] > ... glibc: [ on ] > ... gtk2: [ on ] > ... libaudit: [ on ] > ...libbfd: [ on ] > ...libcap: [ on ] > ...libelf: [ on ] > ... libnuma: [ on ] > ...numa_num_possible_cpus: [ on ] > ... libperl: [ on ] > ... libpython: [ on ] > ... libcrypto: [ on ] > ... libunwind: [ on ] > ...libdw-dwarf-unwind: [ on ] > ... zlib: [ on ] > ... lzma: [ on ] > ... get_cpuid: [ OFF ] > ... bpf: [ on ] > ...libaio: [ on ] > ... libzstd: [ on ] > ...disassembler-four-args: [ on ] Thank you for posting your configuration. I will see where things are different with mine. > > I also could not reproduce on x86: > lsb_release -a: Ubuntu 18.04.1 LTS > gcc --version: gcc (Ubuntu 7.4.0-1ubuntu1~18.04aka10.0.0) 7.4.0 > uname -r: 4.4.0-154-generic
RE: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
> On Wed, August 14, 2019 at 2:52 PM Arnaldo Carvalho de Melo > wrote: > Em Wed, Aug 14, 2019 at 03:48:14PM -0300, Arnaldo Carvalho de Melo > escreveu: > > Em Wed, Aug 14, 2019 at 12:04:33PM -0600, Mathieu Poirier escreveu: > > > # 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... > > Can't repro: > > [root@quaco ~]# cat /proc/sys/kernel/kptr_restrict > 0 > [root@quaco ~]# perf record -e instructions:k uname Linux [ perf record: > Woken up 1 times to write data ] [ perf record: Captured and wrote 0.024 MB > perf.data (1 samples) ] [root@quaco ~]# echo 1 > > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e instructions:k > uname Linux [ perf record: Woken up 1 times to write data ] [ perf record: > Captured and wrote 0.024 MB perf.data (1 samples) ] [root@quaco ~]# echo > 0 > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e > instructions:k uname Linux [ perf record: Woken up 1 times to write data ] [ > perf record: Captured and wrote 0.024 MB perf.data (1 samples) ] > [root@quaco ~]# > > [acme@quaco perf]$ git log --oneline --author Lubashev tools/ > 7ff5b5911144 (HEAD -> perf/cap, acme.korg/tmp.perf/cap, > acme.korg/perf/cap) perf symbols: Use CAP_SYSLOG with kptr_restrict > checks d7604b66102e perf tools: Use CAP_SYS_ADMIN with > perf_event_paranoid checks c766f3df635d perf ftrace: Use CAP_SYS_ADMIN > instead of euid==0 c22e150e3afa perf tools: Add helpers to use capabilities if > present > 74d5f3d06f70 tools build: Add capability-related feature detection perf > version 5.3.rc4.g7ff5b5911144 [acme@quaco perf]$ I got an ARM64 cloud VM, but I cannot reproduce. # cat /proc/sys/kernel/kptr_restrict 0 Perf trace works fine (does not die): # ./perf trace -a Here is my setup: Repo: git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git Branch: tmp.perf/cap Commit: 7ff5b5911 "perf symbols: Use CAP_SYSLOG with kptr_restrict checks" gcc --version: gcc (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1) 7.4.0 uname -a: Linux arm-4-par-1 4.9.93-mainline-rev1 #1 SMP Tue Apr 10 09:54:46 UTC 2018 aarch64 aarch64 aarch64 GNU/Linux lsb_release -a: Ubuntu 18.04.3 LTS Auto-detecting system features: ... dwarf: [ on ] ...dwarf_getlocations: [ on ] ... glibc: [ on ] ... gtk2: [ on ] ... libaudit: [ on ] ...libbfd: [ on ] ...libcap: [ on ] ...libelf: [ on ] ... libnuma: [ on ] ...numa_num_possible_cpus: [ on ] ... libperl: [ on ] ... libpython: [ on ] ... libcrypto: [ on ] ... libunwind: [ on ] ...libdw-dwarf-unwind: [ on ] ... zlib: [ on ] ... lzma: [ on ] ... get_cpuid: [ OFF ] ... bpf: [ on ] ...libaio: [ on ] ... libzstd: [ on ] ...disassembler-four-args: [ on ] I also could not reproduce on x86: lsb_release -a: Ubuntu 18.04.1 LTS gcc --version: gcc (Ubuntu 7.4.0-1ubuntu1~18.04aka10.0.0) 7.4.0 uname -r: 4.4.0-154-generic
Re: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
Em Wed, Aug 14, 2019 at 03:48:14PM -0300, Arnaldo Carvalho de Melo escreveu: > Em Wed, Aug 14, 2019 at 12:04:33PM -0600, Mathieu Poirier escreveu: > > # 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... Can't repro: [root@quaco ~]# cat /proc/sys/kernel/kptr_restrict 0 [root@quaco ~]# perf record -e instructions:k uname Linux [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.024 MB perf.data (1 samples) ] [root@quaco ~]# echo 1 > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e instructions:k uname Linux [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.024 MB perf.data (1 samples) ] [root@quaco ~]# echo 0 > /proc/sys/kernel/kptr_restrict [root@quaco ~]# perf record -e instructions:k uname Linux [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.024 MB perf.data (1 samples) ] [root@quaco ~]# [acme@quaco perf]$ git log --oneline --author Lubashev tools/ 7ff5b5911144 (HEAD -> perf/cap, acme.korg/tmp.perf/cap, acme.korg/perf/cap) perf symbols: Use CAP_SYSLOG with kptr_restrict checks d7604b66102e perf tools: Use CAP_SYS_ADMIN with perf_event_paranoid checks c766f3df635d perf ftrace: Use CAP_SYS_ADMIN instead of euid==0 c22e150e3afa perf tools: Add helpers to use capabilities if present 74d5f3d06f70 tools build: Add capability-related feature detection perf version 5.3.rc4.g7ff5b5911144 [acme@quaco perf]$ - Arnaldo
Re: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
Em Wed, Aug 14, 2019 at 12:04:33PM -0600, Mathieu Poirier escreveu:
> On Wed, 7 Aug 2019 at 08:44, Igor Lubashev 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
> > ---
> > 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
> > #include
> > #include
> > +#include
> > #include
> > #include
> > #include
> > @@ -15,8 +16,10 @@
> > #include
> > #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
Re: [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
On Wed, 7 Aug 2019 at 08:44, Igor Lubashev 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
> ---
> 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
> #include
> #include
> +#include
> #include
> #include
> #include
> @@ -15,8 +16,10 @@
> #include
> #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.
> if (r != NULL) {
> @@ -2190,9 +2197,9 @@ static bool symbol__read_kptr_restrict(void)
> char line[8];
>
> if (fgets(line, sizeof(line), fp) != NULL)
> - value = ((geteuid() != 0) || (getuid() != 0)) ?
> - (atoi(line) != 0) :
> - (atoi(line) == 2);
> + value = perf_cap__capable(CAP_SYSLOG) ?
> + (atoi(line) >= 2) :
> + (atoi(line) != 0);
>
> fclose(fp);
> }
> --
> 2.7.4
>
