| Message ID | c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Introduce CAP_PERFMON to secure system performance monitoring and observability | expand |
Hi, Is there anything else I could do in order to move the changes forward or is something still missing from this patch set? Could you please share you mind? Thanks, Alexey On 17.02.2020 11:02, Alexey Budankov wrote: > > Currently access to perf_events, i915_perf and other performance > monitoring and observability subsystems of the kernel is open only for > a privileged process [1] with CAP_SYS_ADMIN capability enabled in the > process effective set [2]. > > This patch set introduces CAP_PERFMON capability designed to secure > system performance monitoring and observability operations so that > CAP_PERFMON would assist CAP_SYS_ADMIN capability in its governing role > for performance monitoring and observability subsystems of the kernel. > > CAP_PERFMON intends to harden system security and integrity during > performance monitoring and observability operations by decreasing attack > surface that is available to a CAP_SYS_ADMIN privileged process [2]. > Providing the access to performance monitoring and observability > operations under CAP_PERFMON capability singly, without the rest of > CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials > and makes the operation more secure. Thus, CAP_PERFMON implements the > principal of least privilege for performance monitoring and > observability operations (POSIX IEEE 1003.1e: 2.2.2.39 principle of > least privilege: A security design principle that states that a process > or program be granted only those privileges (e.g., capabilities) > necessary to accomplish its legitimate function, and only for the time > that such privileges are actually required) > > CAP_PERFMON intends to meet the demand to secure system performance > monitoring and observability operations for adoption in security > sensitive, restricted, multiuser production environments (e.g. HPC > clusters, cloud and virtual compute environments), where root or > CAP_SYS_ADMIN credentials are not available to mass users of a system, > and securely unblock accessibility of system performance monitoring and > observability operations beyond root and CAP_SYS_ADMIN use cases. > > CAP_PERFMON intends to take over CAP_SYS_ADMIN credentials related to > system performance monitoring and observability operations and balance > amount of CAP_SYS_ADMIN credentials following the recommendations in > the capabilities man page [2] for CAP_SYS_ADMIN: "Note: this capability > is overloaded; see Notes to kernel developers, below." For backward > compatibility reasons access to system performance monitoring and > observability subsystems of the kernel remains open for CAP_SYS_ADMIN > privileged processes but CAP_SYS_ADMIN capability usage for secure > system performance monitoring and observability operations is > discouraged with respect to the designed CAP_PERFMON capability. > > Possible alternative solution to this system security hardening, > capabilities balancing task of making performance monitoring and > observability operations more secure and accessible could be to use > the existing CAP_SYS_PTRACE capability to govern system performance > monitoring and observability subsystems. However CAP_SYS_PTRACE > capability still provides users with more credentials than are > required for secure performance monitoring and observability > operations and this excess is avoided by the designed CAP_PERFMON. > > Although software running under CAP_PERFMON can not ensure avoidance of > related hardware issues, the software can still mitigate those issues > following the official hardware issues mitigation procedure [3]. The > bugs in the software itself can be fixed following the standard kernel > development process [4] to maintain and harden security of system > performance monitoring and observability operations. Finally, the patch > set is shaped in the way that simplifies backtracking procedure of > possible induced issues [5] as much as possible. > > The patch set is for tip perf/core repository: > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip perf/core > sha1: fdb64822443ec9fb8c3a74b598a74790ae8d2e22 > > --- > Changes in v7: > - updated and extended kernel.rst and perf-security.rst documentation > files with the information about CAP_PERFMON capability and its use cases > - documented the case of double audit logging of CAP_PERFMON and CAP_SYS_ADMIN > capabilities on a SELinux enabled system > Changes in v6: > - avoided noaudit checks in perfmon_capable() to explicitly advertise > CAP_PERFMON usage thru audit logs to secure system performance > monitoring and observability > Changes in v5: > - renamed CAP_SYS_PERFMON to CAP_PERFMON > - extended perfmon_capable() with noaudit checks > Changes in v4: > - converted perfmon_capable() into an inline function > - made perf_events kprobes, uprobes, hw breakpoints and namespaces data > available to CAP_SYS_PERFMON privileged processes > - applied perfmon_capable() to drivers/perf and drivers/oprofile > - extended __cmd_ftrace() with support of CAP_SYS_PERFMON > Changes in v3: > - implemented perfmon_capable() macros aggregating required capabilities > checks > Changes in v2: > - made perf_events trace points available to CAP_SYS_PERFMON privileged > processes > - made perf_event_paranoid_check() treat CAP_SYS_PERFMON equally to > CAP_SYS_ADMIN > - applied CAP_SYS_PERFMON to i915_perf, bpf_trace, powerpc and parisc > system performance monitoring and observability related subsystems > > --- > Alexey Budankov (12): > capabilities: introduce CAP_PERFMON to kernel and user space > perf/core: open access to the core for CAP_PERFMON privileged process > perf/core: open access to probes for CAP_PERFMON privileged process > perf tool: extend Perf tool with CAP_PERFMON capability support > drm/i915/perf: open access for CAP_PERFMON privileged process > trace/bpf_trace: open access for CAP_PERFMON privileged process > powerpc/perf: open access for CAP_PERFMON privileged process > parisc/perf: open access for CAP_PERFMON privileged process > drivers/perf: open access for CAP_PERFMON privileged process > drivers/oprofile: open access for CAP_PERFMON privileged process > doc/admin-guide: update perf-security.rst with CAP_PERFMON information > doc/admin-guide: update kernel.rst with CAP_PERFMON information > > Documentation/admin-guide/perf-security.rst | 65 +++++++++++++-------- > Documentation/admin-guide/sysctl/kernel.rst | 16 +++-- > arch/parisc/kernel/perf.c | 2 +- > arch/powerpc/perf/imc-pmu.c | 4 +- > drivers/gpu/drm/i915/i915_perf.c | 13 ++--- > drivers/oprofile/event_buffer.c | 2 +- > drivers/perf/arm_spe_pmu.c | 4 +- > include/linux/capability.h | 4 ++ > include/linux/perf_event.h | 6 +- > include/uapi/linux/capability.h | 8 ++- > kernel/events/core.c | 6 +- > kernel/trace/bpf_trace.c | 2 +- > security/selinux/include/classmap.h | 4 +- > tools/perf/builtin-ftrace.c | 5 +- > tools/perf/design.txt | 3 +- > tools/perf/util/cap.h | 4 ++ > tools/perf/util/evsel.c | 10 ++-- > tools/perf/util/util.c | 1 + > 18 files changed, 98 insertions(+), 61 deletions(-) > > --- > Validation (Intel Skylake, 8 cores, Fedora 29, 5.5.0-rc3+, x86_64): > > libcap library [6], [7], [8] and Perf tool can be used to apply > CAP_PERFMON capability for secure system performance monitoring and > observability beyond the scope permitted by the system wide > perf_event_paranoid kernel setting [9] and below are the steps for > evaluation: > > - patch, build and boot the kernel > - patch, build Perf tool e.g. to /home/user/perf > ... > # git clone git://git.kernel.org/pub/scm/libs/libcap/libcap.git libcap > # pushd libcap > # patch libcap/include/uapi/linux/capabilities.h with [PATCH 1] > # make > # pushd progs > # ./setcap "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" /home/user/perf > # ./setcap -v "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" /home/user/perf > /home/user/perf: OK > # ./getcap /home/user/perf > /home/user/perf = cap_sys_ptrace,cap_syslog,cap_perfmon+ep > # echo 2 > /proc/sys/kernel/perf_event_paranoid > # cat /proc/sys/kernel/perf_event_paranoid > 2 > ... > $ /home/user/perf top > ... works as expected ... > $ cat /proc/`pidof perf`/status > Name: perf > Umask: 0002 > State: S (sleeping) > Tgid: 2958 > Ngid: 0 > Pid: 2958 > PPid: 9847 > TracerPid: 0 > Uid: 500 500 500 500 > Gid: 500 500 500 500 > FDSize: 256 > ... > CapInh: 0000000000000000 > CapPrm: 0000004400080000 > CapEff: 0000004400080000 => 01000100 00000000 00001000 00000000 00000000 > cap_perfmon,cap_sys_ptrace,cap_syslog > CapBnd: 0000007fffffffff > CapAmb: 0000000000000000 > NoNewPrivs: 0 > Seccomp: 0 > Speculation_Store_Bypass: thread vulnerable > Cpus_allowed: ff > Cpus_allowed_list: 0-7 > ... > > Usage of cap_perfmon effectively avoids unused credentials excess: > > - with cap_sys_admin: > CapEff: 0000007fffffffff => 01111111 11111111 11111111 11111111 11111111 > > - with cap_perfmon: > CapEff: 0000004400080000 => 01000100 00000000 00001000 00000000 00000000 > 38 34 19 > perfmon syslog sys_ptrace > > --- > [1] https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html > [2] http://man7.org/linux/man-pages/man7/capabilities.7.html > [3] https://www.kernel.org/doc/html/latest/process/embargoed-hardware-issues.html > [4] https://www.kernel.org/doc/html/latest/admin-guide/security-bugs.html > [5] https://www.kernel.org/doc/html/latest/process/management-style.html#decisions > [6] http://man7.org/linux/man-pages/man8/setcap.8.html > [7] https://git.kernel.org/pub/scm/libs/libcap/libcap.git > [8] https://sites.google.com/site/fullycapable/, posix_1003.1e-990310.pdf > [9] http://man7.org/linux/man-pages/man2/perf_event_open.2.html >
Thanks, this looks good to me, in keeping with the CAP_SYSLOG break. Acked-by: Serge E. Hallyn <serge@hallyn.com> for the set. James/Ingo/Peter, if noone has remaining objections, whose branch should these go in through? thanks, -serge On Tue, Feb 25, 2020 at 12:55:54PM +0300, Alexey Budankov wrote: > > Hi, > > Is there anything else I could do in order to move the changes forward > or is something still missing from this patch set? > Could you please share you mind? > > Thanks, > Alexey > > On 17.02.2020 11:02, Alexey Budankov wrote: > > > > Currently access to perf_events, i915_perf and other performance > > monitoring and observability subsystems of the kernel is open only for > > a privileged process [1] with CAP_SYS_ADMIN capability enabled in the > > process effective set [2]. > > > > This patch set introduces CAP_PERFMON capability designed to secure > > system performance monitoring and observability operations so that > > CAP_PERFMON would assist CAP_SYS_ADMIN capability in its governing role > > for performance monitoring and observability subsystems of the kernel. > > > > CAP_PERFMON intends to harden system security and integrity during > > performance monitoring and observability operations by decreasing attack > > surface that is available to a CAP_SYS_ADMIN privileged process [2]. > > Providing the access to performance monitoring and observability > > operations under CAP_PERFMON capability singly, without the rest of > > CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials > > and makes the operation more secure. Thus, CAP_PERFMON implements the > > principal of least privilege for performance monitoring and > > observability operations (POSIX IEEE 1003.1e: 2.2.2.39 principle of > > least privilege: A security design principle that states that a process > > or program be granted only those privileges (e.g., capabilities) > > necessary to accomplish its legitimate function, and only for the time > > that such privileges are actually required) > > > > CAP_PERFMON intends to meet the demand to secure system performance > > monitoring and observability operations for adoption in security > > sensitive, restricted, multiuser production environments (e.g. HPC > > clusters, cloud and virtual compute environments), where root or > > CAP_SYS_ADMIN credentials are not available to mass users of a system, > > and securely unblock accessibility of system performance monitoring and > > observability operations beyond root and CAP_SYS_ADMIN use cases. > > > > CAP_PERFMON intends to take over CAP_SYS_ADMIN credentials related to > > system performance monitoring and observability operations and balance > > amount of CAP_SYS_ADMIN credentials following the recommendations in > > the capabilities man page [2] for CAP_SYS_ADMIN: "Note: this capability > > is overloaded; see Notes to kernel developers, below." For backward > > compatibility reasons access to system performance monitoring and > > observability subsystems of the kernel remains open for CAP_SYS_ADMIN > > privileged processes but CAP_SYS_ADMIN capability usage for secure > > system performance monitoring and observability operations is > > discouraged with respect to the designed CAP_PERFMON capability. > > > > Possible alternative solution to this system security hardening, > > capabilities balancing task of making performance monitoring and > > observability operations more secure and accessible could be to use > > the existing CAP_SYS_PTRACE capability to govern system performance > > monitoring and observability subsystems. However CAP_SYS_PTRACE > > capability still provides users with more credentials than are > > required for secure performance monitoring and observability > > operations and this excess is avoided by the designed CAP_PERFMON. > > > > Although software running under CAP_PERFMON can not ensure avoidance of > > related hardware issues, the software can still mitigate those issues > > following the official hardware issues mitigation procedure [3]. The > > bugs in the software itself can be fixed following the standard kernel > > development process [4] to maintain and harden security of system > > performance monitoring and observability operations. Finally, the patch > > set is shaped in the way that simplifies backtracking procedure of > > possible induced issues [5] as much as possible. > > > > The patch set is for tip perf/core repository: > > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip perf/core > > sha1: fdb64822443ec9fb8c3a74b598a74790ae8d2e22 > > > > --- > > Changes in v7: > > - updated and extended kernel.rst and perf-security.rst documentation > > files with the information about CAP_PERFMON capability and its use cases > > - documented the case of double audit logging of CAP_PERFMON and CAP_SYS_ADMIN > > capabilities on a SELinux enabled system > > Changes in v6: > > - avoided noaudit checks in perfmon_capable() to explicitly advertise > > CAP_PERFMON usage thru audit logs to secure system performance > > monitoring and observability > > Changes in v5: > > - renamed CAP_SYS_PERFMON to CAP_PERFMON > > - extended perfmon_capable() with noaudit checks > > Changes in v4: > > - converted perfmon_capable() into an inline function > > - made perf_events kprobes, uprobes, hw breakpoints and namespaces data > > available to CAP_SYS_PERFMON privileged processes > > - applied perfmon_capable() to drivers/perf and drivers/oprofile > > - extended __cmd_ftrace() with support of CAP_SYS_PERFMON > > Changes in v3: > > - implemented perfmon_capable() macros aggregating required capabilities > > checks > > Changes in v2: > > - made perf_events trace points available to CAP_SYS_PERFMON privileged > > processes > > - made perf_event_paranoid_check() treat CAP_SYS_PERFMON equally to > > CAP_SYS_ADMIN > > - applied CAP_SYS_PERFMON to i915_perf, bpf_trace, powerpc and parisc > > system performance monitoring and observability related subsystems > > > > --- > > Alexey Budankov (12): > > capabilities: introduce CAP_PERFMON to kernel and user space > > perf/core: open access to the core for CAP_PERFMON privileged process > > perf/core: open access to probes for CAP_PERFMON privileged process > > perf tool: extend Perf tool with CAP_PERFMON capability support > > drm/i915/perf: open access for CAP_PERFMON privileged process > > trace/bpf_trace: open access for CAP_PERFMON privileged process > > powerpc/perf: open access for CAP_PERFMON privileged process > > parisc/perf: open access for CAP_PERFMON privileged process > > drivers/perf: open access for CAP_PERFMON privileged process > > drivers/oprofile: open access for CAP_PERFMON privileged process > > doc/admin-guide: update perf-security.rst with CAP_PERFMON information > > doc/admin-guide: update kernel.rst with CAP_PERFMON information > > > > Documentation/admin-guide/perf-security.rst | 65 +++++++++++++-------- > > Documentation/admin-guide/sysctl/kernel.rst | 16 +++-- > > arch/parisc/kernel/perf.c | 2 +- > > arch/powerpc/perf/imc-pmu.c | 4 +- > > drivers/gpu/drm/i915/i915_perf.c | 13 ++--- > > drivers/oprofile/event_buffer.c | 2 +- > > drivers/perf/arm_spe_pmu.c | 4 +- > > include/linux/capability.h | 4 ++ > > include/linux/perf_event.h | 6 +- > > include/uapi/linux/capability.h | 8 ++- > > kernel/events/core.c | 6 +- > > kernel/trace/bpf_trace.c | 2 +- > > security/selinux/include/classmap.h | 4 +- > > tools/perf/builtin-ftrace.c | 5 +- > > tools/perf/design.txt | 3 +- > > tools/perf/util/cap.h | 4 ++ > > tools/perf/util/evsel.c | 10 ++-- > > tools/perf/util/util.c | 1 + > > 18 files changed, 98 insertions(+), 61 deletions(-) > > > > --- > > Validation (Intel Skylake, 8 cores, Fedora 29, 5.5.0-rc3+, x86_64): > > > > libcap library [6], [7], [8] and Perf tool can be used to apply > > CAP_PERFMON capability for secure system performance monitoring and > > observability beyond the scope permitted by the system wide > > perf_event_paranoid kernel setting [9] and below are the steps for > > evaluation: > > > > - patch, build and boot the kernel > > - patch, build Perf tool e.g. to /home/user/perf > > ... > > # git clone git://git.kernel.org/pub/scm/libs/libcap/libcap.git libcap > > # pushd libcap > > # patch libcap/include/uapi/linux/capabilities.h with [PATCH 1] > > # make > > # pushd progs > > # ./setcap "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" /home/user/perf > > # ./setcap -v "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" /home/user/perf > > /home/user/perf: OK > > # ./getcap /home/user/perf > > /home/user/perf = cap_sys_ptrace,cap_syslog,cap_perfmon+ep > > # echo 2 > /proc/sys/kernel/perf_event_paranoid > > # cat /proc/sys/kernel/perf_event_paranoid > > 2 > > ... > > $ /home/user/perf top > > ... works as expected ... > > $ cat /proc/`pidof perf`/status > > Name: perf > > Umask: 0002 > > State: S (sleeping) > > Tgid: 2958 > > Ngid: 0 > > Pid: 2958 > > PPid: 9847 > > TracerPid: 0 > > Uid: 500 500 500 500 > > Gid: 500 500 500 500 > > FDSize: 256 > > ... > > CapInh: 0000000000000000 > > CapPrm: 0000004400080000 > > CapEff: 0000004400080000 => 01000100 00000000 00001000 00000000 00000000 > > cap_perfmon,cap_sys_ptrace,cap_syslog > > CapBnd: 0000007fffffffff > > CapAmb: 0000000000000000 > > NoNewPrivs: 0 > > Seccomp: 0 > > Speculation_Store_Bypass: thread vulnerable > > Cpus_allowed: ff > > Cpus_allowed_list: 0-7 > > ... > > > > Usage of cap_perfmon effectively avoids unused credentials excess: > > > > - with cap_sys_admin: > > CapEff: 0000007fffffffff => 01111111 11111111 11111111 11111111 11111111 > > > > - with cap_perfmon: > > CapEff: 0000004400080000 => 01000100 00000000 00001000 00000000 00000000 > > 38 34 19 > > perfmon syslog sys_ptrace > > > > --- > > [1] https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html > > [2] http://man7.org/linux/man-pages/man7/capabilities.7.html > > [3] https://www.kernel.org/doc/html/latest/process/embargoed-hardware-issues.html > > [4] https://www.kernel.org/doc/html/latest/admin-guide/security-bugs.html > > [5] https://www.kernel.org/doc/html/latest/process/management-style.html#decisions > > [6] http://man7.org/linux/man-pages/man8/setcap.8.html > > [7] https://git.kernel.org/pub/scm/libs/libcap/libcap.git > > [8] https://sites.google.com/site/fullycapable/, posix_1003.1e-990310.pdf > > [9] http://man7.org/linux/man-pages/man2/perf_event_open.2.html > > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
On Sun, 1 Mar 2020, Serge Hallyn wrote: > Thanks, this looks good to me, in keeping with the CAP_SYSLOG break. > > Acked-by: Serge E. Hallyn <serge@hallyn.com> > > for the set. > > James/Ingo/Peter, if noone has remaining objections, whose branch > should these go in through? > > thanks, I was assuming via the perf tree, but I am happy to take them. > -serge > > On Tue, Feb 25, 2020 at 12:55:54PM +0300, Alexey Budankov wrote: > > > > Hi, > > > > Is there anything else I could do in order to move the changes forward > > or is something still missing from this patch set? > > Could you please share you mind? > > > > Thanks, > > Alexey > > > > On 17.02.2020 11:02, Alexey Budankov wrote: > > > > > > Currently access to perf_events, i915_perf and other performance > > > monitoring and observability subsystems of the kernel is open only for > > > a privileged process [1] with CAP_SYS_ADMIN capability enabled in the > > > process effective set [2]. > > > > > > This patch set introduces CAP_PERFMON capability designed to secure > > > system performance monitoring and observability operations so that > > > CAP_PERFMON would assist CAP_SYS_ADMIN capability in its governing role > > > for performance monitoring and observability subsystems of the kernel. > > > > > > CAP_PERFMON intends to harden system security and integrity during > > > performance monitoring and observability operations by decreasing attack > > > surface that is available to a CAP_SYS_ADMIN privileged process [2]. > > > Providing the access to performance monitoring and observability > > > operations under CAP_PERFMON capability singly, without the rest of > > > CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials > > > and makes the operation more secure. Thus, CAP_PERFMON implements the > > > principal of least privilege for performance monitoring and > > > observability operations (POSIX IEEE 1003.1e: 2.2.2.39 principle of > > > least privilege: A security design principle that states that a process > > > or program be granted only those privileges (e.g., capabilities) > > > necessary to accomplish its legitimate function, and only for the time > > > that such privileges are actually required) > > > > > > CAP_PERFMON intends to meet the demand to secure system performance > > > monitoring and observability operations for adoption in security > > > sensitive, restricted, multiuser production environments (e.g. HPC > > > clusters, cloud and virtual compute environments), where root or > > > CAP_SYS_ADMIN credentials are not available to mass users of a system, > > > and securely unblock accessibility of system performance monitoring and > > > observability operations beyond root and CAP_SYS_ADMIN use cases. > > > > > > CAP_PERFMON intends to take over CAP_SYS_ADMIN credentials related to > > > system performance monitoring and observability operations and balance > > > amount of CAP_SYS_ADMIN credentials following the recommendations in > > > the capabilities man page [2] for CAP_SYS_ADMIN: "Note: this capability > > > is overloaded; see Notes to kernel developers, below." For backward > > > compatibility reasons access to system performance monitoring and > > > observability subsystems of the kernel remains open for CAP_SYS_ADMIN > > > privileged processes but CAP_SYS_ADMIN capability usage for secure > > > system performance monitoring and observability operations is > > > discouraged with respect to the designed CAP_PERFMON capability. > > > > > > Possible alternative solution to this system security hardening, > > > capabilities balancing task of making performance monitoring and > > > observability operations more secure and accessible could be to use > > > the existing CAP_SYS_PTRACE capability to govern system performance > > > monitoring and observability subsystems. However CAP_SYS_PTRACE > > > capability still provides users with more credentials than are > > > required for secure performance monitoring and observability > > > operations and this excess is avoided by the designed CAP_PERFMON. > > > > > > Although software running under CAP_PERFMON can not ensure avoidance of > > > related hardware issues, the software can still mitigate those issues > > > following the official hardware issues mitigation procedure [3]. The > > > bugs in the software itself can be fixed following the standard kernel > > > development process [4] to maintain and harden security of system > > > performance monitoring and observability operations. Finally, the patch > > > set is shaped in the way that simplifies backtracking procedure of > > > possible induced issues [5] as much as possible. > > > > > > The patch set is for tip perf/core repository: > > > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip perf/core > > > sha1: fdb64822443ec9fb8c3a74b598a74790ae8d2e22 > > > > > > --- > > > Changes in v7: > > > - updated and extended kernel.rst and perf-security.rst documentation > > > files with the information about CAP_PERFMON capability and its use cases > > > - documented the case of double audit logging of CAP_PERFMON and CAP_SYS_ADMIN > > > capabilities on a SELinux enabled system > > > Changes in v6: > > > - avoided noaudit checks in perfmon_capable() to explicitly advertise > > > CAP_PERFMON usage thru audit logs to secure system performance > > > monitoring and observability > > > Changes in v5: > > > - renamed CAP_SYS_PERFMON to CAP_PERFMON > > > - extended perfmon_capable() with noaudit checks > > > Changes in v4: > > > - converted perfmon_capable() into an inline function > > > - made perf_events kprobes, uprobes, hw breakpoints and namespaces data > > > available to CAP_SYS_PERFMON privileged processes > > > - applied perfmon_capable() to drivers/perf and drivers/oprofile > > > - extended __cmd_ftrace() with support of CAP_SYS_PERFMON > > > Changes in v3: > > > - implemented perfmon_capable() macros aggregating required capabilities > > > checks > > > Changes in v2: > > > - made perf_events trace points available to CAP_SYS_PERFMON privileged > > > processes > > > - made perf_event_paranoid_check() treat CAP_SYS_PERFMON equally to > > > CAP_SYS_ADMIN > > > - applied CAP_SYS_PERFMON to i915_perf, bpf_trace, powerpc and parisc > > > system performance monitoring and observability related subsystems > > > > > > --- > > > Alexey Budankov (12): > > > capabilities: introduce CAP_PERFMON to kernel and user space > > > perf/core: open access to the core for CAP_PERFMON privileged process > > > perf/core: open access to probes for CAP_PERFMON privileged process > > > perf tool: extend Perf tool with CAP_PERFMON capability support > > > drm/i915/perf: open access for CAP_PERFMON privileged process > > > trace/bpf_trace: open access for CAP_PERFMON privileged process > > > powerpc/perf: open access for CAP_PERFMON privileged process > > > parisc/perf: open access for CAP_PERFMON privileged process > > > drivers/perf: open access for CAP_PERFMON privileged process > > > drivers/oprofile: open access for CAP_PERFMON privileged process > > > doc/admin-guide: update perf-security.rst with CAP_PERFMON information > > > doc/admin-guide: update kernel.rst with CAP_PERFMON information > > > > > > Documentation/admin-guide/perf-security.rst | 65 +++++++++++++-------- > > > Documentation/admin-guide/sysctl/kernel.rst | 16 +++-- > > > arch/parisc/kernel/perf.c | 2 +- > > > arch/powerpc/perf/imc-pmu.c | 4 +- > > > drivers/gpu/drm/i915/i915_perf.c | 13 ++--- > > > drivers/oprofile/event_buffer.c | 2 +- > > > drivers/perf/arm_spe_pmu.c | 4 +- > > > include/linux/capability.h | 4 ++ > > > include/linux/perf_event.h | 6 +- > > > include/uapi/linux/capability.h | 8 ++- > > > kernel/events/core.c | 6 +- > > > kernel/trace/bpf_trace.c | 2 +- > > > security/selinux/include/classmap.h | 4 +- > > > tools/perf/builtin-ftrace.c | 5 +- > > > tools/perf/design.txt | 3 +- > > > tools/perf/util/cap.h | 4 ++ > > > tools/perf/util/evsel.c | 10 ++-- > > > tools/perf/util/util.c | 1 + > > > 18 files changed, 98 insertions(+), 61 deletions(-) > > > > > > --- > > > Validation (Intel Skylake, 8 cores, Fedora 29, 5.5.0-rc3+, x86_64): > > > > > > libcap library [6], [7], [8] and Perf tool can be used to apply > > > CAP_PERFMON capability for secure system performance monitoring and > > > observability beyond the scope permitted by the system wide > > > perf_event_paranoid kernel setting [9] and below are the steps for > > > evaluation: > > > > > > - patch, build and boot the kernel > > > - patch, build Perf tool e.g. to /home/user/perf > > > ... > > > # git clone git://git.kernel.org/pub/scm/libs/libcap/libcap.git libcap > > > # pushd libcap > > > # patch libcap/include/uapi/linux/capabilities.h with [PATCH 1] > > > # make > > > # pushd progs > > > # ./setcap "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" /home/user/perf > > > # ./setcap -v "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" /home/user/perf > > > /home/user/perf: OK > > > # ./getcap /home/user/perf > > > /home/user/perf = cap_sys_ptrace,cap_syslog,cap_perfmon+ep > > > # echo 2 > /proc/sys/kernel/perf_event_paranoid > > > # cat /proc/sys/kernel/perf_event_paranoid > > > 2 > > > ... > > > $ /home/user/perf top > > > ... works as expected ... > > > $ cat /proc/`pidof perf`/status > > > Name: perf > > > Umask: 0002 > > > State: S (sleeping) > > > Tgid: 2958 > > > Ngid: 0 > > > Pid: 2958 > > > PPid: 9847 > > > TracerPid: 0 > > > Uid: 500 500 500 500 > > > Gid: 500 500 500 500 > > > FDSize: 256 > > > ... > > > CapInh: 0000000000000000 > > > CapPrm: 0000004400080000 > > > CapEff: 0000004400080000 => 01000100 00000000 00001000 00000000 00000000 > > > cap_perfmon,cap_sys_ptrace,cap_syslog > > > CapBnd: 0000007fffffffff > > > CapAmb: 0000000000000000 > > > NoNewPrivs: 0 > > > Seccomp: 0 > > > Speculation_Store_Bypass: thread vulnerable > > > Cpus_allowed: ff > > > Cpus_allowed_list: 0-7 > > > ... > > > > > > Usage of cap_perfmon effectively avoids unused credentials excess: > > > > > > - with cap_sys_admin: > > > CapEff: 0000007fffffffff => 01111111 11111111 11111111 11111111 11111111 > > > > > > - with cap_perfmon: > > > CapEff: 0000004400080000 => 01000100 00000000 00001000 00000000 00000000 > > > 38 34 19 > > > perfmon syslog sys_ptrace > > > > > > --- > > > [1] https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html > > > [2] http://man7.org/linux/man-pages/man7/capabilities.7.html > > > [3] https://www.kernel.org/doc/html/latest/process/embargoed-hardware-issues.html > > > [4] https://www.kernel.org/doc/html/latest/admin-guide/security-bugs.html > > > [5] https://www.kernel.org/doc/html/latest/process/management-style.html#decisions > > > [6] http://man7.org/linux/man-pages/man8/setcap.8.html > > > [7] https://git.kernel.org/pub/scm/libs/libcap/libcap.git > > > [8] https://sites.google.com/site/fullycapable/, posix_1003.1e-990310.pdf > > > [9] http://man7.org/linux/man-pages/man2/perf_event_open.2.html > > > > > _______________________________________________ > > Intel-gfx mailing list > > Intel-gfx@lists.freedesktop.org > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx >
On Sun, 1 Mar 2020, Serge Hallyn wrote: > Thanks, this looks good to me, in keeping with the CAP_SYSLOG break. > > Acked-by: Serge E. Hallyn <serge@hallyn.com> > > for the set. > > James/Ingo/Peter, if noone has remaining objections, whose branch > should these go in through? > > thanks, > -serge > > On Tue, Feb 25, 2020 at 12:55:54PM +0300, Alexey Budankov wrote: > > > > Hi, > > > > Is there anything else I could do in order to move the changes forward > > or is something still missing from this patch set? > > Could you please share you mind? Alexey, It seems some of the previous Acks are not included in this patchset, e.g. https://lkml.org/lkml/2020/1/22/655 Every patch needs a Reviewed-by or Acked-by from maintainers of the code being changed. You have enough from the security folk, but I can't see any included from the perf folk.
Currently access to perf_events, i915_perf and other performance monitoring and observability subsystems of the kernel is open only for a privileged process [1] with CAP_SYS_ADMIN capability enabled in the process effective set [2]. This patch set introduces CAP_PERFMON capability designed to secure system performance monitoring and observability operations so that CAP_PERFMON would assist CAP_SYS_ADMIN capability in its governing role for performance monitoring and observability subsystems of the kernel. CAP_PERFMON intends to harden system security and integrity during performance monitoring and observability operations by decreasing attack surface that is available to a CAP_SYS_ADMIN privileged process [2]. Providing the access to performance monitoring and observability operations under CAP_PERFMON capability singly, without the rest of CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials and makes the operation more secure. Thus, CAP_PERFMON implements the principal of least privilege for performance monitoring and observability operations (POSIX IEEE 1003.1e: 2.2.2.39 principle of least privilege: A security design principle that states that a process or program be granted only those privileges (e.g., capabilities) necessary to accomplish its legitimate function, and only for the time that such privileges are actually required) CAP_PERFMON intends to meet the demand to secure system performance monitoring and observability operations for adoption in security sensitive, restricted, multiuser production environments (e.g. HPC clusters, cloud and virtual compute environments), where root or CAP_SYS_ADMIN credentials are not available to mass users of a system, and securely unblock accessibility of system performance monitoring and observability operations beyond root and CAP_SYS_ADMIN use cases. CAP_PERFMON intends to take over CAP_SYS_ADMIN credentials related to system performance monitoring and observability operations and balance amount of CAP_SYS_ADMIN credentials following the recommendations in the capabilities man page [2] for CAP_SYS_ADMIN: "Note: this capability is overloaded; see Notes to kernel developers, below." For backward compatibility reasons access to system performance monitoring and observability subsystems of the kernel remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN capability usage for secure system performance monitoring and observability operations is discouraged with respect to the designed CAP_PERFMON capability. Possible alternative solution to this system security hardening, capabilities balancing task of making performance monitoring and observability operations more secure and accessible could be to use the existing CAP_SYS_PTRACE capability to govern system performance monitoring and observability subsystems. However CAP_SYS_PTRACE capability still provides users with more credentials than are required for secure performance monitoring and observability operations and this excess is avoided by the designed CAP_PERFMON. Although software running under CAP_PERFMON can not ensure avoidance of related hardware issues, the software can still mitigate those issues following the official hardware issues mitigation procedure [3]. The bugs in the software itself can be fixed following the standard kernel development process [4] to maintain and harden security of system performance monitoring and observability operations. Finally, the patch set is shaped in the way that simplifies backtracking procedure of possible induced issues [5] as much as possible. The patch set is for tip perf/core repository: git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip perf/core sha1: fdb64822443ec9fb8c3a74b598a74790ae8d2e22 --- Changes in v7: - updated and extended kernel.rst and perf-security.rst documentation files with the information about CAP_PERFMON capability and its use cases - documented the case of double audit logging of CAP_PERFMON and CAP_SYS_ADMIN capabilities on a SELinux enabled system Changes in v6: - avoided noaudit checks in perfmon_capable() to explicitly advertise CAP_PERFMON usage thru audit logs to secure system performance monitoring and observability Changes in v5: - renamed CAP_SYS_PERFMON to CAP_PERFMON - extended perfmon_capable() with noaudit checks Changes in v4: - converted perfmon_capable() into an inline function - made perf_events kprobes, uprobes, hw breakpoints and namespaces data available to CAP_SYS_PERFMON privileged processes - applied perfmon_capable() to drivers/perf and drivers/oprofile - extended __cmd_ftrace() with support of CAP_SYS_PERFMON Changes in v3: - implemented perfmon_capable() macros aggregating required capabilities checks Changes in v2: - made perf_events trace points available to CAP_SYS_PERFMON privileged processes - made perf_event_paranoid_check() treat CAP_SYS_PERFMON equally to CAP_SYS_ADMIN - applied CAP_SYS_PERFMON to i915_perf, bpf_trace, powerpc and parisc system performance monitoring and observability related subsystems --- Alexey Budankov (12): capabilities: introduce CAP_PERFMON to kernel and user space perf/core: open access to the core for CAP_PERFMON privileged process perf/core: open access to probes for CAP_PERFMON privileged process perf tool: extend Perf tool with CAP_PERFMON capability support drm/i915/perf: open access for CAP_PERFMON privileged process trace/bpf_trace: open access for CAP_PERFMON privileged process powerpc/perf: open access for CAP_PERFMON privileged process parisc/perf: open access for CAP_PERFMON privileged process drivers/perf: open access for CAP_PERFMON privileged process drivers/oprofile: open access for CAP_PERFMON privileged process doc/admin-guide: update perf-security.rst with CAP_PERFMON information doc/admin-guide: update kernel.rst with CAP_PERFMON information Documentation/admin-guide/perf-security.rst | 65 +++++++++++++-------- Documentation/admin-guide/sysctl/kernel.rst | 16 +++-- arch/parisc/kernel/perf.c | 2 +- arch/powerpc/perf/imc-pmu.c | 4 +- drivers/gpu/drm/i915/i915_perf.c | 13 ++--- drivers/oprofile/event_buffer.c | 2 +- drivers/perf/arm_spe_pmu.c | 4 +- include/linux/capability.h | 4 ++ include/linux/perf_event.h | 6 +- include/uapi/linux/capability.h | 8 ++- kernel/events/core.c | 6 +- kernel/trace/bpf_trace.c | 2 +- security/selinux/include/classmap.h | 4 +- tools/perf/builtin-ftrace.c | 5 +- tools/perf/design.txt | 3 +- tools/perf/util/cap.h | 4 ++ tools/perf/util/evsel.c | 10 ++-- tools/perf/util/util.c | 1 + 18 files changed, 98 insertions(+), 61 deletions(-) --- Validation (Intel Skylake, 8 cores, Fedora 29, 5.5.0-rc3+, x86_64): libcap library [6], [7], [8] and Perf tool can be used to apply CAP_PERFMON capability for secure system performance monitoring and observability beyond the scope permitted by the system wide perf_event_paranoid kernel setting [9] and below are the steps for evaluation: - patch, build and boot the kernel - patch, build Perf tool e.g. to /home/user/perf ... # git clone git://git.kernel.org/pub/scm/libs/libcap/libcap.git libcap # pushd libcap # patch libcap/include/uapi/linux/capabilities.h with [PATCH 1] # make # pushd progs # ./setcap "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" /home/user/perf # ./setcap -v "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" /home/user/perf /home/user/perf: OK # ./getcap /home/user/perf /home/user/perf = cap_sys_ptrace,cap_syslog,cap_perfmon+ep # echo 2 > /proc/sys/kernel/perf_event_paranoid # cat /proc/sys/kernel/perf_event_paranoid 2 ... $ /home/user/perf top ... works as expected ... $ cat /proc/`pidof perf`/status Name: perf Umask: 0002 State: S (sleeping) Tgid: 2958 Ngid: 0 Pid: 2958 PPid: 9847 TracerPid: 0 Uid: 500 500 500 500 Gid: 500 500 500 500 FDSize: 256 ... CapInh: 0000000000000000 CapPrm: 0000004400080000 CapEff: 0000004400080000 => 01000100 00000000 00001000 00000000 00000000 cap_perfmon,cap_sys_ptrace,cap_syslog CapBnd: 0000007fffffffff CapAmb: 0000000000000000 NoNewPrivs: 0 Seccomp: 0 Speculation_Store_Bypass: thread vulnerable Cpus_allowed: ff Cpus_allowed_list: 0-7 ... Usage of cap_perfmon effectively avoids unused credentials excess: - with cap_sys_admin: CapEff: 0000007fffffffff => 01111111 11111111 11111111 11111111 11111111 - with cap_perfmon: CapEff: 0000004400080000 => 01000100 00000000 00001000 00000000 00000000 38 34 19 perfmon syslog sys_ptrace --- [1] https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html [2] http://man7.org/linux/man-pages/man7/capabilities.7.html [3] https://www.kernel.org/doc/html/latest/process/embargoed-hardware-issues.html [4] https://www.kernel.org/doc/html/latest/admin-guide/security-bugs.html [5] https://www.kernel.org/doc/html/latest/process/management-style.html#decisions [6] http://man7.org/linux/man-pages/man8/setcap.8.html [7] https://git.kernel.org/pub/scm/libs/libcap/libcap.git [8] https://sites.google.com/site/fullycapable/, posix_1003.1e-990310.pdf [9] http://man7.org/linux/man-pages/man2/perf_event_open.2.html