* [PATCH v7 12/12] doc/admin-guide: update kernel.rst with CAP_PERFMON information
From: Alexey Budankov @ 2020-02-17 8:13 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>
Update kernel.rst documentation file with the information
related to usage of CAP_PERFMON capability to secure performance
monitoring and observability operations in system.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
Documentation/admin-guide/sysctl/kernel.rst | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index def074807cee..b06ae9389809 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -720,20 +720,26 @@ perf_event_paranoid:
====================
Controls use of the performance events system by unprivileged
-users (without CAP_SYS_ADMIN). The default value is 2.
+users (without CAP_PERFMON). The default value is 2.
+
+For backward compatibility reasons access to system performance
+monitoring and observability remains open for CAP_SYS_ADMIN
+privileged processes but CAP_SYS_ADMIN usage for secure system
+performance monitoring and observability operations is discouraged
+with respect to CAP_PERFMON use cases.
=== ==================================================================
-1 Allow use of (almost) all events by all users
Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
->=0 Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN
+>=0 Disallow ftrace function tracepoint by users without CAP_PERFMON
- Disallow raw tracepoint access by users without CAP_SYS_ADMIN
+ Disallow raw tracepoint access by users without CAP_PERFMON
->=1 Disallow CPU event access by users without CAP_SYS_ADMIN
+>=1 Disallow CPU event access by users without CAP_PERFMON
->=2 Disallow kernel profiling by users without CAP_SYS_ADMIN
+>=2 Disallow kernel profiling by users without CAP_PERFMON
=== ==================================================================
--
2.20.1
^ permalink raw reply related
* [PATCH v7 11/12] doc/admin-guide: update perf-security.rst with CAP_PERFMON information
From: Alexey Budankov @ 2020-02-17 8:12 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>
Update perf-security.rst documentation file with the information
related to usage of CAP_PERFMON capability to secure performance
monitoring and observability operations in system.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
Documentation/admin-guide/perf-security.rst | 65 +++++++++++++--------
1 file changed, 40 insertions(+), 25 deletions(-)
diff --git a/Documentation/admin-guide/perf-security.rst b/Documentation/admin-guide/perf-security.rst
index 72effa7c23b9..81202d46a1ae 100644
--- a/Documentation/admin-guide/perf-security.rst
+++ b/Documentation/admin-guide/perf-security.rst
@@ -1,6 +1,6 @@
.. _perf_security:
-Perf Events and tool security
+Perf events and tool security
=============================
Overview
@@ -42,11 +42,11 @@ categories:
Data that belong to the fourth category can potentially contain
sensitive process data. If PMUs in some monitoring modes capture values
of execution context registers or data from process memory then access
-to such monitoring capabilities requires to be ordered and secured
-properly. So, perf_events/Perf performance monitoring is the subject for
-security access control management [5]_ .
+to such monitoring modes requires to be ordered and secured properly.
+So, perf_events performance monitoring and observability operations is
+the subject for security access control management [5]_ .
-perf_events/Perf access control
+perf_events access control
-------------------------------
To perform security checks, the Linux implementation splits processes
@@ -66,11 +66,25 @@ into distinct units, known as capabilities [6]_ , which can be
independently enabled and disabled on per-thread basis for processes and
files of unprivileged users.
-Unprivileged processes with enabled CAP_SYS_ADMIN capability are treated
+Unprivileged processes with enabled CAP_PERFMON capability are treated
as privileged processes with respect to perf_events performance
-monitoring and bypass *scope* permissions checks in the kernel.
-
-Unprivileged processes using perf_events system call API is also subject
+monitoring and observability operations, thus, bypass *scope* permissions
+checks in the kernel. CAP_PERFMON implements the principal of least
+privilege [13]_ (POSIX 1003.1e: 2.2.2.39) for performance monitoring and
+observability operations in the kernel and provides secure approach to
+perfomance monitoring and observability in the system.
+
+For backward compatibility reasons access to perf_events monitoring and
+observability operations is also open for CAP_SYS_ADMIN privileged
+processes but CAP_SYS_ADMIN usage for secure monitoring and observability
+use cases is discouraged with respect to CAP_PERFMON capability.
+If system audit records [14]_ for a process using perf_events system call
+API contain denial records of acquiring both CAP_PERFMON and CAP_SYS_ADMIN
+capabilities then providing the process with CAP_PERFMON capability singly
+is recommended as the preferred secure approach to resolve double access
+denial logging related to usage of performance monitoring and observability.
+
+Unprivileged processes using perf_events system call are also subject
for PTRACE_MODE_READ_REALCREDS ptrace access mode check [7]_ , whose
outcome determines whether monitoring is permitted. So unprivileged
processes provided with CAP_SYS_PTRACE capability are effectively
@@ -82,14 +96,14 @@ performance analysis of monitored processes or a system. For example,
CAP_SYSLOG capability permits reading kernel space memory addresses from
/proc/kallsyms file.
-perf_events/Perf privileged users
+Privileged Perf users groups
---------------------------------
Mechanisms of capabilities, privileged capability-dumb files [6]_ and
-file system ACLs [10]_ can be used to create a dedicated group of
-perf_events/Perf privileged users who are permitted to execute
-performance monitoring without scope limits. The following steps can be
-taken to create such a group of privileged Perf users.
+file system ACLs [10]_ can be used to create dedicated groups of
+privileged Perf users who are permitted to execute performance monitoring
+and observability without scope limits. The following steps can be
+taken to create such groups of privileged Perf users.
1. Create perf_users group of privileged Perf users, assign perf_users
group to Perf tool executable and limit access to the executable for
@@ -108,30 +122,30 @@ taken to create such a group of privileged Perf users.
-rwxr-x--- 2 root perf_users 11M Oct 19 15:12 perf
2. Assign the required capabilities to the Perf tool executable file and
- enable members of perf_users group with performance monitoring
+ enable members of perf_users group with monitoring and observability
privileges [6]_ :
::
- # setcap "cap_sys_admin,cap_sys_ptrace,cap_syslog=ep" perf
- # setcap -v "cap_sys_admin,cap_sys_ptrace,cap_syslog=ep" perf
+ # setcap "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" perf
+ # setcap -v "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" perf
perf: OK
# getcap perf
- perf = cap_sys_ptrace,cap_sys_admin,cap_syslog+ep
+ perf = cap_sys_ptrace,cap_syslog,cap_perfmon+ep
As a result, members of perf_users group are capable of conducting
-performance monitoring by using functionality of the configured Perf
-tool executable that, when executes, passes perf_events subsystem scope
-checks.
+performance monitoring and observability by using functionality of the
+configured Perf tool executable that, when executes, passes perf_events
+subsystem scope checks.
This specific access control management is only available to superuser
or root running processes with CAP_SETPCAP, CAP_SETFCAP [6]_
capabilities.
-perf_events/Perf unprivileged users
+Unprivileged users
-----------------------------------
-perf_events/Perf *scope* and *access* control for unprivileged processes
+perf_events *scope* and *access* control for unprivileged processes
is governed by perf_event_paranoid [2]_ setting:
-1:
@@ -166,7 +180,7 @@ is governed by perf_event_paranoid [2]_ setting:
perf_event_mlock_kb locking limit is imposed but ignored for
unprivileged processes with CAP_IPC_LOCK capability.
-perf_events/Perf resource control
+Resource control
---------------------------------
Open file descriptors
@@ -227,4 +241,5 @@ Bibliography
.. [10] `<http://man7.org/linux/man-pages/man5/acl.5.html>`_
.. [11] `<http://man7.org/linux/man-pages/man2/getrlimit.2.html>`_
.. [12] `<http://man7.org/linux/man-pages/man5/limits.conf.5.html>`_
-
+.. [13] `<https://sites.google.com/site/fullycapable>`_
+.. [14] `<http://man7.org/linux/man-pages/man8/auditd.8.html>`_
--
2.20.1
^ permalink raw reply related
* [PATCH v7 10/12] drivers/oprofile: open access for CAP_PERFMON privileged process
From: Alexey Budankov @ 2020-02-17 8:12 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>
Open access to monitoring for CAP_PERFMON privileged process.
Providing the access under CAP_PERFMON capability singly, without
the rest of CAP_SYS_ADMIN credentials, excludes chances to misuse
the credentials and makes operation more secure.
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)
For backward compatibility reasons access to the monitoring remains
open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage
for secure monitoring is discouraged with respect to CAP_PERFMON
capability.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
drivers/oprofile/event_buffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/oprofile/event_buffer.c b/drivers/oprofile/event_buffer.c
index 12ea4a4ad607..6c9edc8bbc95 100644
--- a/drivers/oprofile/event_buffer.c
+++ b/drivers/oprofile/event_buffer.c
@@ -113,7 +113,7 @@ static int event_buffer_open(struct inode *inode, struct file *file)
{
int err = -EPERM;
- if (!capable(CAP_SYS_ADMIN))
+ if (!perfmon_capable())
return -EPERM;
if (test_and_set_bit_lock(0, &buffer_opened))
--
2.20.1
^ permalink raw reply related
* [PATCH v7 09/12] drivers/perf: open access for CAP_PERFMON privileged process
From: Alexey Budankov @ 2020-02-17 8:11 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>
Open access to monitoring for CAP_PERFMON privileged process.
Providing the access under CAP_PERFMON capability singly, without
the rest of CAP_SYS_ADMIN credentials, excludes chances to misuse
the credentials and makes operation more secure.
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)
For backward compatibility reasons access to the monitoring remains
open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage
for secure monitoring is discouraged with respect to CAP_PERFMON
capability.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
drivers/perf/arm_spe_pmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
index 4e4984a55cd1..5dff81bc3324 100644
--- a/drivers/perf/arm_spe_pmu.c
+++ b/drivers/perf/arm_spe_pmu.c
@@ -274,7 +274,7 @@ static u64 arm_spe_event_to_pmscr(struct perf_event *event)
if (!attr->exclude_kernel)
reg |= BIT(SYS_PMSCR_EL1_E1SPE_SHIFT);
- if (IS_ENABLED(CONFIG_PID_IN_CONTEXTIDR) && capable(CAP_SYS_ADMIN))
+ if (IS_ENABLED(CONFIG_PID_IN_CONTEXTIDR) && perfmon_capable())
reg |= BIT(SYS_PMSCR_EL1_CX_SHIFT);
return reg;
@@ -700,7 +700,7 @@ static int arm_spe_pmu_event_init(struct perf_event *event)
return -EOPNOTSUPP;
reg = arm_spe_event_to_pmscr(event);
- if (!capable(CAP_SYS_ADMIN) &&
+ if (!perfmon_capable() &&
(reg & (BIT(SYS_PMSCR_EL1_PA_SHIFT) |
BIT(SYS_PMSCR_EL1_CX_SHIFT) |
BIT(SYS_PMSCR_EL1_PCT_SHIFT))))
--
2.20.1
^ permalink raw reply related
* [PATCH v7 08/12] parisc/perf: open access for CAP_PERFMON privileged process
From: Alexey Budankov @ 2020-02-17 8:10 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>
Open access to monitoring for CAP_PERFMON privileged process.
Providing the access under CAP_PERFMON capability singly, without
the rest of CAP_SYS_ADMIN credentials, excludes chances to misuse
the credentials and makes operation more secure.
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)
For backward compatibility reasons access to the monitoring remains
open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage
for secure monitoring is discouraged with respect to CAP_PERFMON
capability.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
arch/parisc/kernel/perf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/parisc/kernel/perf.c b/arch/parisc/kernel/perf.c
index e1a8fee3ad49..d46b6709ec56 100644
--- a/arch/parisc/kernel/perf.c
+++ b/arch/parisc/kernel/perf.c
@@ -300,7 +300,7 @@ static ssize_t perf_write(struct file *file, const char __user *buf,
else
return -EFAULT;
- if (!capable(CAP_SYS_ADMIN))
+ if (!perfmon_capable())
return -EACCES;
if (count != sizeof(uint32_t))
--
2.20.1
^ permalink raw reply related
* [PATCH v7 07/12] powerpc/perf: open access for CAP_PERFMON privileged process
From: Alexey Budankov @ 2020-02-17 8:10 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>
Open access to monitoring for CAP_PERFMON privileged process.
Providing the access under CAP_PERFMON capability singly, without
the rest of CAP_SYS_ADMIN credentials, excludes chances to misuse
the credentials and makes operation more secure.
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)
For backward compatibility reasons access to the monitoring remains
open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN usage
for secure monitoring is discouraged with respect to CAP_PERFMON
capability.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
arch/powerpc/perf/imc-pmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
index cb50a9e1fd2d..e837717492e4 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -898,7 +898,7 @@ static int thread_imc_event_init(struct perf_event *event)
if (event->attr.type != event->pmu->type)
return -ENOENT;
- if (!capable(CAP_SYS_ADMIN))
+ if (!perfmon_capable())
return -EACCES;
/* Sampling not supported */
@@ -1307,7 +1307,7 @@ static int trace_imc_event_init(struct perf_event *event)
if (event->attr.type != event->pmu->type)
return -ENOENT;
- if (!capable(CAP_SYS_ADMIN))
+ if (!perfmon_capable())
return -EACCES;
/* Return if this is a couting event */
--
2.20.1
^ permalink raw reply related
* [PATCH v7 06/12] trace/bpf_trace: open access for CAP_PERFMON privileged process
From: Alexey Budankov @ 2020-02-17 8:09 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>
Open access to bpf_trace monitoring for CAP_PERFMON privileged process.
Providing the access under CAP_PERFMON capability singly, without the
rest of CAP_SYS_ADMIN credentials, excludes chances to misuse the
credentials and makes operation more secure.
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)
For backward compatibility reasons access to bpf_trace monitoring
remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN
usage for secure bpf_trace monitoring is discouraged with respect to
CAP_PERFMON capability.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
kernel/trace/bpf_trace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 19e793aa441a..70e8249eebe5 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1416,7 +1416,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)
u32 *ids, prog_cnt, ids_len;
int ret;
- if (!capable(CAP_SYS_ADMIN))
+ if (!perfmon_capable())
return -EPERM;
if (event->attr.type != PERF_TYPE_TRACEPOINT)
return -EINVAL;
--
2.20.1
^ permalink raw reply related
* [PATCH v7 05/12] drm/i915/perf: open access for CAP_PERFMON privileged process
From: Alexey Budankov @ 2020-02-17 8:08 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>
Open access to i915_perf monitoring for CAP_PERFMON privileged process.
Providing the access under CAP_PERFMON capability singly, without the
rest of CAP_SYS_ADMIN credentials, excludes chances to misuse the
credentials and makes operation more secure.
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)
For backward compatibility reasons access to i915_events subsystem
remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN
usage for secure i915_events monitoring is discouraged with respect to
CAP_PERFMON capability.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
drivers/gpu/drm/i915/i915_perf.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 0f556d80ba36..a3f32bd0aa47 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -3378,10 +3378,10 @@ i915_perf_open_ioctl_locked(struct i915_perf *perf,
/* Similar to perf's kernel.perf_paranoid_cpu sysctl option
* we check a dev.i915.perf_stream_paranoid sysctl option
* to determine if it's ok to access system wide OA counters
- * without CAP_SYS_ADMIN privileges.
+ * without CAP_PERFMON or CAP_SYS_ADMIN privileges.
*/
if (privileged_op &&
- i915_perf_stream_paranoid && !capable(CAP_SYS_ADMIN)) {
+ i915_perf_stream_paranoid && !perfmon_capable()) {
DRM_DEBUG("Insufficient privileges to open i915 perf stream\n");
ret = -EACCES;
goto err_ctx;
@@ -3574,9 +3574,8 @@ static int read_properties_unlocked(struct i915_perf *perf,
} else
oa_freq_hz = 0;
- if (oa_freq_hz > i915_oa_max_sample_rate &&
- !capable(CAP_SYS_ADMIN)) {
- DRM_DEBUG("OA exponent would exceed the max sampling frequency (sysctl dev.i915.oa_max_sample_rate) %uHz without root privileges\n",
+ if (oa_freq_hz > i915_oa_max_sample_rate && !perfmon_capable()) {
+ DRM_DEBUG("OA exponent would exceed the max sampling frequency (sysctl dev.i915.oa_max_sample_rate) %uHz without CAP_PERFMON or CAP_SYS_ADMIN privileges\n",
i915_oa_max_sample_rate);
return -EACCES;
}
@@ -3997,7 +3996,7 @@ int i915_perf_add_config_ioctl(struct drm_device *dev, void *data,
return -EINVAL;
}
- if (i915_perf_stream_paranoid && !capable(CAP_SYS_ADMIN)) {
+ if (i915_perf_stream_paranoid && !perfmon_capable()) {
DRM_DEBUG("Insufficient privileges to add i915 OA config\n");
return -EACCES;
}
@@ -4144,7 +4143,7 @@ int i915_perf_remove_config_ioctl(struct drm_device *dev, void *data,
return -ENOTSUPP;
}
- if (i915_perf_stream_paranoid && !capable(CAP_SYS_ADMIN)) {
+ if (i915_perf_stream_paranoid && !perfmon_capable()) {
DRM_DEBUG("Insufficient privileges to remove i915 OA config\n");
return -EACCES;
}
--
2.20.1
^ permalink raw reply related
* [PATCH v7 04/12] perf tool: extend Perf tool with CAP_PERFMON capability support
From: Alexey Budankov @ 2020-02-17 8:08 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>
Extend error messages to mention CAP_PERFMON capability as an option
to substitute CAP_SYS_ADMIN capability for secure system performance
monitoring and observability. Make perf_event_paranoid_check() and
__cmd_ftrace() to be aware of CAP_PERFMON capability.
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)
For backward compatibility reasons access to perf_events subsystem
remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN
usage for secure perf_events monitoring is discouraged with respect to
CAP_PERFMON capability.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
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 +
5 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index d5adc417a4ca..55eda54240fb 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -284,10 +284,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
.events = POLLIN,
};
- if (!perf_cap__capable(CAP_SYS_ADMIN)) {
+ if (!(perf_cap__capable(CAP_PERFMON) ||
+ perf_cap__capable(CAP_SYS_ADMIN))) {
pr_err("ftrace only works for %s!\n",
#ifdef HAVE_LIBCAP_SUPPORT
- "users with the SYS_ADMIN capability"
+ "users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
#else
"root"
#endif
diff --git a/tools/perf/design.txt b/tools/perf/design.txt
index 0453ba26cdbd..a42fab308ff6 100644
--- a/tools/perf/design.txt
+++ b/tools/perf/design.txt
@@ -258,7 +258,8 @@ gets schedule to. Per task counters can be created by any user, for
their own tasks.
A 'pid == -1' and 'cpu == x' counter is a per CPU counter that counts
-all events on CPU-x. Per CPU counters need CAP_SYS_ADMIN privilege.
+all events on CPU-x. Per CPU counters need CAP_PERFMON or CAP_SYS_ADMIN
+privilege.
The 'flags' parameter is currently unused and must be zero.
diff --git a/tools/perf/util/cap.h b/tools/perf/util/cap.h
index 051dc590ceee..ae52878c0b2e 100644
--- a/tools/perf/util/cap.h
+++ b/tools/perf/util/cap.h
@@ -29,4 +29,8 @@ static inline bool perf_cap__capable(int cap __maybe_unused)
#define CAP_SYSLOG 34
#endif
+#ifndef CAP_PERFMON
+#define CAP_PERFMON 38
+#endif
+
#endif /* __PERF_CAP_H */
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index c8dc4450884c..da57d1d4c601 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2493,14 +2493,14 @@ int perf_evsel__open_strerror(struct evsel *evsel, struct target *target,
"You may not have permission to collect %sstats.\n\n"
"Consider tweaking /proc/sys/kernel/perf_event_paranoid,\n"
"which controls use of the performance events system by\n"
- "unprivileged users (without CAP_SYS_ADMIN).\n\n"
+ "unprivileged users (without CAP_PERFMON or CAP_SYS_ADMIN).\n\n"
"The current value is %d:\n\n"
" -1: Allow use of (almost) all events by all users\n"
" Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK\n"
- ">= 0: Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN\n"
- " Disallow raw tracepoint access by users without CAP_SYS_ADMIN\n"
- ">= 1: Disallow CPU event access by users without CAP_SYS_ADMIN\n"
- ">= 2: Disallow kernel profiling by users without CAP_SYS_ADMIN\n\n"
+ ">= 0: Disallow ftrace function tracepoint by users without CAP_PERFMON or CAP_SYS_ADMIN\n"
+ " Disallow raw tracepoint access by users without CAP_SYS_PERFMON or CAP_SYS_ADMIN\n"
+ ">= 1: Disallow CPU event access by users without CAP_PERFMON or CAP_SYS_ADMIN\n"
+ ">= 2: Disallow kernel profiling by users without CAP_PERFMON or CAP_SYS_ADMIN\n\n"
"To make this setting permanent, edit /etc/sysctl.conf too, e.g.:\n\n"
" kernel.perf_event_paranoid = -1\n" ,
target->system_wide ? "system-wide " : "",
diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 969ae560dad9..51cf3071db74 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -272,6 +272,7 @@ int perf_event_paranoid(void)
bool perf_event_paranoid_check(int max_level)
{
return perf_cap__capable(CAP_SYS_ADMIN) ||
+ perf_cap__capable(CAP_PERFMON) ||
perf_event_paranoid() <= max_level;
}
--
2.20.1
^ permalink raw reply related
* [PATCH v7 03/12] perf/core: open access to probes for CAP_PERFMON privileged process
From: Alexey Budankov @ 2020-02-17 8:07 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>
Open access to monitoring via kprobes and uprobes and eBPF tracing for
CAP_PERFMON privileged process. Providing the access under CAP_PERFMON
capability singly, without the rest of CAP_SYS_ADMIN credentials,
excludes chances to misuse the credentials and makes operation more
secure.
perf kprobes and uprobes are used by ftrace and eBPF. perf probe uses
ftrace to define new kprobe events, and those events are treated as
tracepoint events. eBPF defines new probes via perf_event_open interface
and then the probes are used in eBPF tracing.
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)
For backward compatibility reasons access to perf_events subsystem
remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN
usage for secure perf_events monitoring is discouraged with respect to
CAP_PERFMON capability.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
kernel/events/core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 46464367c47a..4564caa2c527 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9107,7 +9107,7 @@ static int perf_kprobe_event_init(struct perf_event *event)
if (event->attr.type != perf_kprobe.type)
return -ENOENT;
- if (!capable(CAP_SYS_ADMIN))
+ if (!perfmon_capable())
return -EACCES;
/*
@@ -9167,7 +9167,7 @@ static int perf_uprobe_event_init(struct perf_event *event)
if (event->attr.type != perf_uprobe.type)
return -ENOENT;
- if (!capable(CAP_SYS_ADMIN))
+ if (!perfmon_capable())
return -EACCES;
/*
--
2.20.1
^ permalink raw reply related
* [PATCH v7 02/12] perf/core: open access to the core for CAP_PERFMON privileged process
From: Alexey Budankov @ 2020-02-17 8:06 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>
Open access to monitoring of kernel code, cpus, tracepoints and
namespaces data for a CAP_PERFMON privileged process. Providing the
access under CAP_PERFMON capability singly, without the rest of
CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials
and makes operation more secure.
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)
For backward compatibility reasons access to perf_events subsystem
remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN
usage for secure perf_events monitoring is discouraged with respect to
CAP_PERFMON capability.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
include/linux/perf_event.h | 6 +++---
kernel/events/core.c | 2 +-
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 68e21e828893..5cbfc06c56b3 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1297,7 +1297,7 @@ static inline int perf_is_paranoid(void)
static inline int perf_allow_kernel(struct perf_event_attr *attr)
{
- if (sysctl_perf_event_paranoid > 1 && !capable(CAP_SYS_ADMIN))
+ if (sysctl_perf_event_paranoid > 1 && !perfmon_capable())
return -EACCES;
return security_perf_event_open(attr, PERF_SECURITY_KERNEL);
@@ -1305,7 +1305,7 @@ static inline int perf_allow_kernel(struct perf_event_attr *attr)
static inline int perf_allow_cpu(struct perf_event_attr *attr)
{
- if (sysctl_perf_event_paranoid > 0 && !capable(CAP_SYS_ADMIN))
+ if (sysctl_perf_event_paranoid > 0 && !perfmon_capable())
return -EACCES;
return security_perf_event_open(attr, PERF_SECURITY_CPU);
@@ -1313,7 +1313,7 @@ static inline int perf_allow_cpu(struct perf_event_attr *attr)
static inline int perf_allow_tracepoint(struct perf_event_attr *attr)
{
- if (sysctl_perf_event_paranoid > -1 && !capable(CAP_SYS_ADMIN))
+ if (sysctl_perf_event_paranoid > -1 && !perfmon_capable())
return -EPERM;
return security_perf_event_open(attr, PERF_SECURITY_TRACEPOINT);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 3f1f77de7247..46464367c47a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11205,7 +11205,7 @@ SYSCALL_DEFINE5(perf_event_open,
}
if (attr.namespaces) {
- if (!capable(CAP_SYS_ADMIN))
+ if (!perfmon_capable())
return -EACCES;
}
--
2.20.1
^ permalink raw reply related
* [PATCH v7 01/12] capabilities: introduce CAP_PERFMON to kernel and user space
From: Alexey Budankov @ 2020-02-17 8:06 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>
Introduce 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.
CAP_PERFMON hardens 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 system 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 meets 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 unblocks accessibility
of system performance monitoring and observability operations beyond
the root and CAP_SYS_ADMIN use cases.
CAP_PERFMON takes over CAP_SYS_ADMIN credentials related to system
performance monitoring and observability operations and balances amount
of CAP_SYS_ADMIN credentials following the recommendations in the
capabilities man page [1] 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 usage for secure system
performance monitoring and observability operations is discouraged with
respect to the designed CAP_PERFMON capability.
Although the software running under CAP_PERFMON can not ensure avoidance
of related hardware issues, the software can still mitigate these issues
following the official hardware issues mitigation procedure [2].
The bugs in the software itself can be fixed following the standard
kernel development process [3] to maintain and harden security of system
performance monitoring and observability operations.
[1] http://man7.org/linux/man-pages/man7/capabilities.7.html
[2] https://www.kernel.org/doc/html/latest/process/embargoed-hardware-issues.html
[3] https://www.kernel.org/doc/html/latest/admin-guide/security-bugs.html
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
include/linux/capability.h | 4 ++++
include/uapi/linux/capability.h | 8 +++++++-
security/selinux/include/classmap.h | 4 ++--
3 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/include/linux/capability.h b/include/linux/capability.h
index ecce0f43c73a..027d7e4a853b 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -251,6 +251,10 @@ extern bool privileged_wrt_inode_uidgid(struct user_namespace *ns, const struct
extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap);
extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
extern bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns);
+static inline bool perfmon_capable(void)
+{
+ return capable(CAP_PERFMON) || capable(CAP_SYS_ADMIN);
+}
/* audit system wants to get cap info from files as well */
extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps);
diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h
index 272dc69fa080..e58c9636741b 100644
--- a/include/uapi/linux/capability.h
+++ b/include/uapi/linux/capability.h
@@ -367,8 +367,14 @@ struct vfs_ns_cap_data {
#define CAP_AUDIT_READ 37
+/*
+ * Allow system performance and observability privileged operations
+ * using perf_events, i915_perf and other kernel subsystems
+ */
+
+#define CAP_PERFMON 38
-#define CAP_LAST_CAP CAP_AUDIT_READ
+#define CAP_LAST_CAP CAP_PERFMON
#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
index 986f3ac14282..d233ab3f1533 100644
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -27,9 +27,9 @@
"audit_control", "setfcap"
#define COMMON_CAP2_PERMS "mac_override", "mac_admin", "syslog", \
- "wake_alarm", "block_suspend", "audit_read"
+ "wake_alarm", "block_suspend", "audit_read", "perfmon"
-#if CAP_LAST_CAP > CAP_AUDIT_READ
+#if CAP_LAST_CAP > CAP_PERFMON
#error New capability defined, please update COMMON_CAP2_PERMS.
#endif
--
2.20.1
^ permalink raw reply related
* [PATCH v7 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability
From: Alexey Budankov @ 2020-02-17 8:02 UTC (permalink / raw)
To: James Morris, Serge Hallyn, Stephen Smalley, Peter Zijlstra,
Arnaldo Carvalho de Melo, Ingo Molnar,
joonas.lahtinen@linux.intel.com, Alexei Starovoitov, Will Deacon,
Paul Mackerras, Helge Deller, Thomas Gleixner
Cc: linux-man, Andi Kleen, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, selinux@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, intel-gfx@lists.freedesktop.org,
Igor Lubashev, linux-kernel, Stephane Eranian,
linux-security-module@vger.kernel.org, oprofile-list, Jiri Olsa,
linux-arm-kernel
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
^ permalink raw reply
* Re: [PATCH] KVM: PPC: Book3S HV: Treat unrecognized TM instructions as illegal
From: Segher Boessenkool @ 2020-02-17 7:37 UTC (permalink / raw)
To: Michael Neuling; +Cc: linuxppc-dev, kvm-ppc, Gustavo Romero
In-Reply-To: <1752a0c735a455c5d3ca09209f5a52748c8f7116.camel@neuling.org>
On Mon, Feb 17, 2020 at 05:23:07PM +1100, Michael Neuling wrote:
> > > Hence, we should NOP this, not generate an illegal.
> >
> > It is not a reserved bit.
> >
> > The IMC entry for it matches op1=011111 op2=1////01110 presumably, which
> > catches all TM instructions and nothing else (bits 0..5 and bits 21..30).
> > That does not look at bit 31, the softpatch handler has to deal with this.
> >
> > Some TM insns have bit 31 as 1 and some have it as /. All instructions
> > with a "." in the mnemonic have bit 31 is 1, all other have it reserved.
> > The tables in appendices D, E, F show tend. and tsr. as having it
> > reserved, which contradicts the individual instruction description (and
> > does not make much sense). (Only tcheck has /, everything else has 1;
> > everything else has a mnemonic with a dot, and does write CR0 always).
>
> Wow, interesting.
>
> P8 seems to be treating 31 as a reserved bit (with the table definition rather
> than the individual instruction description). I'm inclined to match P8 even
> though it's inconsistent with the dot mnemonic as you say.
"The POWER8 core ignores the state of reserved bits in the instructions
(denoted by “///” in the instruction definition) and executes the
instruction normally. Software should set these bits to ‘0’ per the
Power ISA." (p8 UM, 3.1.1.3; same in the p9 UM).
Segher
^ permalink raw reply
* Re: [PATCH 2/5] mm/vma: Make vma_is_accessible() available for general use
From: Geert Uytterhoeven @ 2020-02-17 7:36 UTC (permalink / raw)
To: Anshuman Khandual
Cc: Rich Felker, Linux-sh list, Peter Zijlstra, Dave Hansen,
linux-mips, Linux MM, Guo Ren, Yoshinori Sato, Ingo Molnar,
Mel Gorman, Steven Rostedt, linux-m68k, Andy Lutomirski,
Thomas Gleixner, Paul Burton, Linux Kernel Mailing List,
Ralf Baechle, Paul Mackerras, Andrew Morton, linuxppc-dev
In-Reply-To: <1581915833-21984-3-git-send-email-anshuman.khandual@arm.com>
On Mon, Feb 17, 2020 at 6:04 AM Anshuman Khandual
<anshuman.khandual@arm.com> wrote:
> Lets move vma_is_accessible() helper to include/linux/mm.h which makes it
> available for general use. While here, this replaces all remaining open
> encodings for VMA access check with vma_is_accessible().
>
> Cc: Guo Ren <guoren@kernel.org>
> Cc: Geert Uytterhoeven <geert@linux-m68k.org
> Cc: Ralf Baechle <ralf@linux-mips.org>
> Cc: Paul Burton <paulburton@kernel.org>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
> Cc: Rich Felker <dalias@libc.org>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-m68k@lists.linux-m68k.org
> Cc: linux-mips@vger.kernel.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-sh@vger.kernel.org
> Cc: linux-mm@kvack.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> arch/m68k/mm/fault.c | 2 +-
For m68k:
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply
* Re: [RFC PATCH v2 00/12] Reduce ifdef mess in ptrace
From: Christophe Leroy @ 2020-02-17 6:49 UTC (permalink / raw)
To: mikey; +Cc: Paul Mackerras, linuxppc-dev, linux-kernel
In-Reply-To: <cover.1561735587.git.christophe.leroy@c-s.fr>
Hi Mikey,
Le 28/06/2019 à 17:47, Christophe Leroy a écrit :
> The purpose of this series is to reduce the amount of #ifdefs
> in ptrace.c
>
Any feedback on this series which aims at fixing the issue you opened at
https://github.com/linuxppc/issues/issues/128 ?
Thanks
Christophe
> This is a first try. Most of it is done, there are still some #ifdefs that
> could go away.
>
> Please comment and tell whether it is worth continuing in that direction.
>
> v2:
> - Fixed several build failures. Now builts cleanly on kisskb, see http://kisskb.ellerman.id.au/kisskb/head/840e53cf913d6096dd60181a085f102c85d6e526/
> - Droped last patch which is not related to ptrace and can be applies independently.
>
> Christophe Leroy (12):
> powerpc: move ptrace into a subdirectory.
> powerpc/ptrace: drop unnecessary #ifdefs CONFIG_PPC64
> powerpc/ptrace: drop PARAMETER_SAVE_AREA_OFFSET
> powerpc/ptrace: split out VSX related functions.
> powerpc/ptrace: split out ALTIVEC related functions.
> powerpc/ptrace: split out SPE related functions.
> powerpc/ptrace: split out TRANSACTIONAL_MEM related functions.
> powerpc/ptrace: move register viewing functions out of ptrace.c
> powerpc/ptrace: split out ADV_DEBUG_REGS related functions.
> powerpc/ptrace: create ptrace_get_debugreg()
> powerpc/ptrace: create ppc_gethwdinfo()
> powerpc/ptrace: move ptrace_triggered() into hw_breakpoint.c
>
> arch/powerpc/include/asm/ptrace.h | 9 +-
> arch/powerpc/include/uapi/asm/ptrace.h | 12 +-
> arch/powerpc/kernel/Makefile | 7 +-
> arch/powerpc/kernel/hw_breakpoint.c | 16 +
> arch/powerpc/kernel/ptrace.c | 3402 ---------------------------
> arch/powerpc/kernel/ptrace/Makefile | 20 +
> arch/powerpc/kernel/ptrace/ptrace-adv.c | 511 ++++
> arch/powerpc/kernel/ptrace/ptrace-altivec.c | 151 ++
> arch/powerpc/kernel/ptrace/ptrace-decl.h | 184 ++
> arch/powerpc/kernel/ptrace/ptrace-noadv.c | 291 +++
> arch/powerpc/kernel/ptrace/ptrace-novsx.c | 83 +
> arch/powerpc/kernel/ptrace/ptrace-spe.c | 92 +
> arch/powerpc/kernel/ptrace/ptrace-tm.c | 879 +++++++
> arch/powerpc/kernel/ptrace/ptrace-view.c | 953 ++++++++
> arch/powerpc/kernel/ptrace/ptrace-vsx.c | 177 ++
> arch/powerpc/kernel/ptrace/ptrace.c | 430 ++++
> arch/powerpc/kernel/{ => ptrace}/ptrace32.c | 0
> 17 files changed, 3798 insertions(+), 3419 deletions(-)
> delete mode 100644 arch/powerpc/kernel/ptrace.c
> create mode 100644 arch/powerpc/kernel/ptrace/Makefile
> create mode 100644 arch/powerpc/kernel/ptrace/ptrace-adv.c
> create mode 100644 arch/powerpc/kernel/ptrace/ptrace-altivec.c
> create mode 100644 arch/powerpc/kernel/ptrace/ptrace-decl.h
> create mode 100644 arch/powerpc/kernel/ptrace/ptrace-noadv.c
> create mode 100644 arch/powerpc/kernel/ptrace/ptrace-novsx.c
> create mode 100644 arch/powerpc/kernel/ptrace/ptrace-spe.c
> create mode 100644 arch/powerpc/kernel/ptrace/ptrace-tm.c
> create mode 100644 arch/powerpc/kernel/ptrace/ptrace-view.c
> create mode 100644 arch/powerpc/kernel/ptrace/ptrace-vsx.c
> create mode 100644 arch/powerpc/kernel/ptrace/ptrace.c
> rename arch/powerpc/kernel/{ => ptrace}/ptrace32.c (100%)
>
^ permalink raw reply
* Re: [PATCH v7 4/4] powerpc: Book3S 64-bit "heavyweight" KASAN support
From: Christophe Leroy @ 2020-02-17 6:45 UTC (permalink / raw)
To: Michael Neuling, Daniel Axtens, linux-kernel, linux-mm,
linuxppc-dev, kasan-dev, aneesh.kumar, bsingharora
In-Reply-To: <66bd9d8eb682cda2d22bea0fd4035ea8e0a3c1fb.camel@neuling.org>
Le 17/02/2020 à 00:08, Michael Neuling a écrit :
> Daniel.
>
> Can you start this commit message with a simple description of what you are
> actually doing? This reads like you've been on a long journey to Mordor and
> back, which as a reader of this patch in the long distant future, I don't care
> about. I just want to know what you're implementing.
>
> Also I'm struggling to review this as I don't know what software or hardware
> mechanisms you are using to perform sanitisation.
KASAN is standard, it's simply using GCC ASAN in kernel mode, ie kernel
is built with -fsanitize=kernel-address
(https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html)
You have more details there:
https://www.kernel.org/doc/html/latest/dev-tools/kasan.html
Christophe
^ permalink raw reply
* Re: [PATCH] powerpc/chrp: Fix enter_rtas() with CONFIG_VMAP_STACK
From: Christophe Leroy @ 2020-02-17 6:40 UTC (permalink / raw)
To: Michael Neuling, Benjamin Herrenschmidt, Paul Mackerras,
Michael Ellerman
Cc: linuxppc-dev, linux-kernel
In-Reply-To: <04cdd26307a1eaebeacc039b207db92e0b6820bb.camel@neuling.org>
Le 16/02/2020 à 23:40, Michael Neuling a écrit :
> On Fri, 2020-02-14 at 08:33 +0000, Christophe Leroy wrote:
>> With CONFIG_VMAP_STACK, data MMU has to be enabled
>> to read data on the stack.
>
> Can you describe what goes wrong without this? Some oops message? rtas blows up?
> Get corrupt data?
Larry reported a machine check. Or in fact, he reported a Oops in
kprobe_handler(), that Oops being a bug in kprobe_handle() triggered by
this machine check.
By converting a VM address to a phys-like address as if is was linear
mem, you get in the dark. Either there is some physical memory at that
address and you corrupt it. Or there is none and you get a machine check.
>
> Also can you say what you're actually doing (ie turning on MSR[DR])
Euh ... I'm saying that data MMU has to be enabled, so I'm enabling it.
>
>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> ---
>> arch/powerpc/kernel/entry_32.S | 9 +++++++--
>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
>> index 0713daa651d9..bc056d906b51 100644
>> --- a/arch/powerpc/kernel/entry_32.S
>> +++ b/arch/powerpc/kernel/entry_32.S
>> @@ -1354,12 +1354,17 @@ _GLOBAL(enter_rtas)
>> mtspr SPRN_SRR0,r8
>> mtspr SPRN_SRR1,r9
>> RFI
>> -1: tophys(r9,r1)
>> +1: tophys_novmstack r9, r1
>> +#ifdef CONFIG_VMAP_STACK
>> + li r0, MSR_KERNEL & ~MSR_IR /* can take DTLB miss */
>
> You're potentially turning on more than MSR DR here. This should be clear in the
> commit message.
Am I ?
At the time of the RFI just above, SRR1 contains the value of r9 which
has been set 2 lines before to MSR_KERNEL & ~(MSR_IR|MSR_DR).
What should be clear in the commit message ?
>
>> + mtmsr r0
>> + isync
>> +#endif
>> lwz r8,INT_FRAME_SIZE+4(r9) /* get return address */
>> lwz r9,8(r9) /* original msr value */
>> addi r1,r1,INT_FRAME_SIZE
>> li r0,0
>> - tophys(r7, r2)
>> + tophys_novmstack r7, r2
>> stw r0, THREAD + RTAS_SP(r7)
>> mtspr SPRN_SRR0,r8
>> mtspr SPRN_SRR1,r9
Christophe
^ permalink raw reply
* Re: [PATCH 1/1] powerpc/cputable: Remove unnecessary copy of cpu_spec->oprofile_type
From: Christophe Leroy @ 2020-02-17 6:31 UTC (permalink / raw)
To: Leonardo Bras, Benjamin Herrenschmidt, Paul Mackerras,
Michael Ellerman, Greg Kroah-Hartman, Thomas Gleixner, desnesn
Cc: linuxppc-dev, linux-kernel
In-Reply-To: <20200215053637.280880-1-leonardo@linux.ibm.com>
Le 15/02/2020 à 06:36, Leonardo Bras a écrit :
> Before checking for cpu_type == NULL, this same copy happens, so doing
> it here will just write the same value to the t->oprofile_type
> again.
>
> Remove the repeated copy, as it is unnecessary.
>
> Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com>
> ---
> arch/powerpc/kernel/cputable.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
> index e745abc5457a..5a87ec96582f 100644
> --- a/arch/powerpc/kernel/cputable.c
> +++ b/arch/powerpc/kernel/cputable.c
> @@ -2197,7 +2197,6 @@ static struct cpu_spec * __init setup_cpu_spec(unsigned long offset,
> */
> if (old.oprofile_cpu_type != NULL) {
> t->oprofile_cpu_type = old.oprofile_cpu_type;
> - t->oprofile_type = old.oprofile_type;
> }
The action being reduced to a single line, the { } should be removed.
Christophe
^ permalink raw reply
* Re: [PATCH v2 00/13] mm: remove __ARCH_HAS_5LEVEL_HACK
From: Mike Rapoport @ 2020-02-17 6:23 UTC (permalink / raw)
To: Russell King - ARM Linux admin
Cc: Rich Felker, linux-ia64, Geert Uytterhoeven, linux-sh, linux-mm,
Paul Mackerras, linux-hexagon, Will Deacon, kvmarm, Jonas Bonn,
linux-arch, Brian Cain, Marc Zyngier, Ley Foon Tan, Mike Rapoport,
Catalin Marinas, Julien Thierry, uclinux-h8-devel, Fenghua Yu,
Arnd Bergmann, Suzuki K Poulose, kvm-ppc, Stefan Kristiansson,
openrisc, Stafford Horne, Guan Xuetao, linux-arm-kernel,
Tony Luck, Yoshinori Sato, linux-kernel, James Morse, nios2-dev,
Andrew Morton, linuxppc-dev
In-Reply-To: <20200216082230.GV25745@shell.armlinux.org.uk>
On Sun, Feb 16, 2020 at 08:22:30AM +0000, Russell King - ARM Linux admin wrote:
> On Sun, Feb 16, 2020 at 10:18:30AM +0200, Mike Rapoport wrote:
> > From: Mike Rapoport <rppt@linux.ibm.com>
> >
> > Hi,
> >
> > These patches convert several architectures to use page table folding and
> > remove __ARCH_HAS_5LEVEL_HACK along with include/asm-generic/5level-fixup.h.
> >
> > The changes are mostly about mechanical replacement of pgd accessors with p4d
> > ones and the addition of higher levels to page table traversals.
> >
> > All the patches were sent separately to the respective arch lists and
> > maintainers hence the "v2" prefix.
>
> You fail to explain why this change which adds 488 additional lines of
> code is desirable.
Right, I should have been more explicit about it.
As Christophe mentioned in his reply, removing 'HACK' and 'fixup' is an
improvement.
Another thing is that when all architectures behave the same it opens
opportunities for cleaning up repeating definitions of page table
manipulation primitives.
> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
> According to speedtest.net: 11.9Mbps down 500kbps up
--
Sincerely yours,
Mike.
^ permalink raw reply
* Re: [PATCH] KVM: PPC: Book3S HV: Treat unrecognized TM instructions as illegal
From: Michael Neuling @ 2020-02-17 6:23 UTC (permalink / raw)
To: Segher Boessenkool; +Cc: linuxppc-dev, kvm-ppc, Gustavo Romero
In-Reply-To: <20200217055712.GS22482@gate.crashing.org>
On Sun, 2020-02-16 at 23:57 -0600, Segher Boessenkool wrote:
> On Mon, Feb 17, 2020 at 12:07:31PM +1100, Michael Neuling wrote:
> > On Thu, 2020-02-13 at 10:15 -0500, Gustavo Romero wrote:
> > > On P9 DD2.2 due to a CPU defect some TM instructions need to be emulated
> > > by
> > > KVM. This is handled at first by the hardware raising a softpatch
> > > interrupt
> > > when certain TM instructions that need KVM assistance are executed in the
> > > guest. Some TM instructions, although not defined in the Power ISA, might
> > > raise a softpatch interrupt. For instance, 'tresume.' instruction as
> > > defined in the ISA must have bit 31 set (1), but an instruction that
> > > matches 'tresume.' OP and XO opcodes but has bit 31 not set (0), like
> > > 0x7cfe9ddc, also raises a softpatch interrupt, for example, if a code
> > > like the following is executed in the guest it will raise a softpatch
> > > interrupt just like a 'tresume.' when the TM facility is enabled:
> > >
> > > int main() { asm("tabort. 0; .long 0x7cfe9ddc;"); }
> > > and then treats the executed instruction as 'nop' whilst it should
> > > actually
> > > be treated as an illegal instruction since it's not defined by the ISA.
> >
> > The ISA has this:
> >
> > 1.3.3 Reserved Fields, Reserved Values, and Reserved SPRs
> >
> > Reserved fields in instructions are ignored by the pro-
> > cessor.
> >
> > Hence the hardware will ignore reserved bits. For example executing your
> > little
> > program on P8 just exits normally with 0x7cfe9ddc being executed as a NOP.
> >
> > Hence, we should NOP this, not generate an illegal.
>
> It is not a reserved bit.
>
> The IMC entry for it matches op1=011111 op2=1////01110 presumably, which
> catches all TM instructions and nothing else (bits 0..5 and bits 21..30).
> That does not look at bit 31, the softpatch handler has to deal with this.
>
> Some TM insns have bit 31 as 1 and some have it as /. All instructions
> with a "." in the mnemonic have bit 31 is 1, all other have it reserved.
> The tables in appendices D, E, F show tend. and tsr. as having it
> reserved, which contradicts the individual instruction description (and
> does not make much sense). (Only tcheck has /, everything else has 1;
> everything else has a mnemonic with a dot, and does write CR0 always).
Wow, interesting.
P8 seems to be treating 31 as a reserved bit (with the table definition rather
than the individual instruction description). I'm inclined to match P8 even
though it's inconsistent with the dot mnemonic as you say.
Mikey
^ permalink raw reply
* Re: [PATCH] KVM: PPC: Book3S HV: Treat unrecognized TM instructions as illegal
From: Segher Boessenkool @ 2020-02-17 5:57 UTC (permalink / raw)
To: Michael Neuling; +Cc: linuxppc-dev, kvm-ppc, Gustavo Romero
In-Reply-To: <29b136e15c2f04f783b54ec98552d1a6009234db.camel@neuling.org>
On Mon, Feb 17, 2020 at 12:07:31PM +1100, Michael Neuling wrote:
> On Thu, 2020-02-13 at 10:15 -0500, Gustavo Romero wrote:
> > On P9 DD2.2 due to a CPU defect some TM instructions need to be emulated by
> > KVM. This is handled at first by the hardware raising a softpatch interrupt
> > when certain TM instructions that need KVM assistance are executed in the
> > guest. Some TM instructions, although not defined in the Power ISA, might
> > raise a softpatch interrupt. For instance, 'tresume.' instruction as
> > defined in the ISA must have bit 31 set (1), but an instruction that
> > matches 'tresume.' OP and XO opcodes but has bit 31 not set (0), like
> > 0x7cfe9ddc, also raises a softpatch interrupt, for example, if a code
> > like the following is executed in the guest it will raise a softpatch
> > interrupt just like a 'tresume.' when the TM facility is enabled:
> >
> > int main() { asm("tabort. 0; .long 0x7cfe9ddc;"); }
> > and then treats the executed instruction as 'nop' whilst it should actually
> > be treated as an illegal instruction since it's not defined by the ISA.
>
> The ISA has this:
>
> 1.3.3 Reserved Fields, Reserved Values, and Reserved SPRs
>
> Reserved fields in instructions are ignored by the pro-
> cessor.
>
> Hence the hardware will ignore reserved bits. For example executing your little
> program on P8 just exits normally with 0x7cfe9ddc being executed as a NOP.
>
> Hence, we should NOP this, not generate an illegal.
It is not a reserved bit.
The IMC entry for it matches op1=011111 op2=1////01110 presumably, which
catches all TM instructions and nothing else (bits 0..5 and bits 21..30).
That does not look at bit 31, the softpatch handler has to deal with this.
Some TM insns have bit 31 as 1 and some have it as /. All instructions
with a "." in the mnemonic have bit 31 is 1, all other have it reserved.
The tables in appendices D, E, F show tend. and tsr. as having it
reserved, which contradicts the individual instruction description (and
does not make much sense). (Only tcheck has /, everything else has 1;
everything else has a mnemonic with a dot, and does write CR0 always).
Segher
^ permalink raw reply
* [PATCH 3/5] mm/vma: Replace all remaining open encodings with is_vm_hugetlb_page()
From: Anshuman Khandual @ 2020-02-17 5:03 UTC (permalink / raw)
To: linux-mm, linux-kernel
Cc: kvm-ppc, Aneesh Kumar K.V, linux-arch, Arnd Bergmann,
Anshuman Khandual, Peter Zijlstra, linuxppc-dev, Nick Piggin,
Arnaldo Carvalho de Melo, Ingo Molnar, Alexander Viro,
linux-fsdevel, Andrew Morton, Will Deacon
In-Reply-To: <1581915833-21984-1-git-send-email-anshuman.khandual@arm.com>
This replaces all remaining open encodings with is_vm_hugetlb_page().
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Will Deacon <will@kernel.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
arch/powerpc/kvm/e500_mmu_host.c | 2 +-
fs/binfmt_elf.c | 2 +-
include/asm-generic/tlb.h | 2 +-
kernel/events/core.c | 3 ++-
4 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index 425d13806645..3922575a1c31 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -422,7 +422,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
break;
}
} else if (vma && hva >= vma->vm_start &&
- (vma->vm_flags & VM_HUGETLB)) {
+ (is_vm_hugetlb_page(vma))) {
unsigned long psize = vma_kernel_pagesize(vma);
tsize = (gtlbe->mas1 & MAS1_TSIZE_MASK) >>
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index f4713ea76e82..6bc97ede10ba 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1317,7 +1317,7 @@ static unsigned long vma_dump_size(struct vm_area_struct *vma,
}
/* Hugetlb memory check */
- if (vma->vm_flags & VM_HUGETLB) {
+ if (is_vm_hugetlb_page(vma)) {
if ((vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_SHARED))
goto whole;
if (!(vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_PRIVATE))
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index f391f6b500b4..d42c236d4965 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -398,7 +398,7 @@ tlb_update_vma_flags(struct mmu_gather *tlb, struct vm_area_struct *vma)
* We rely on tlb_end_vma() to issue a flush, such that when we reset
* these values the batch is empty.
*/
- tlb->vma_huge = !!(vma->vm_flags & VM_HUGETLB);
+ tlb->vma_huge = is_vm_hugetlb_page(vma);
tlb->vma_exec = !!(vma->vm_flags & VM_EXEC);
}
diff --git a/kernel/events/core.c b/kernel/events/core.c
index e453589da97c..eb0ee3c5f322 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -28,6 +28,7 @@
#include <linux/export.h>
#include <linux/vmalloc.h>
#include <linux/hardirq.h>
+#include <linux/hugetlb_inline.h>
#include <linux/rculist.h>
#include <linux/uaccess.h>
#include <linux/syscalls.h>
@@ -7693,7 +7694,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
flags |= MAP_EXECUTABLE;
if (vma->vm_flags & VM_LOCKED)
flags |= MAP_LOCKED;
- if (vma->vm_flags & VM_HUGETLB)
+ if (is_vm_hugetlb_page(vma))
flags |= MAP_HUGETLB;
if (file) {
--
2.20.1
^ permalink raw reply related
* [PATCH 2/5] mm/vma: Make vma_is_accessible() available for general use
From: Anshuman Khandual @ 2020-02-17 5:03 UTC (permalink / raw)
To: linux-mm, linux-kernel
Cc: Rich Felker, linux-sh, Peter Zijlstra, Dave Hansen, Guo Ren,
Yoshinori Sato, Ingo Molnar, Geert Uytterhoeven, Mel Gorman,
Anshuman Khandual, Steven Rostedt, linux-m68k, Andy Lutomirski,
Thomas Gleixner, Paul Burton, linux-mips, Ralf Baechle,
Paul Mackerras, Andrew Morton, linuxppc-dev
In-Reply-To: <1581915833-21984-1-git-send-email-anshuman.khandual@arm.com>
Lets move vma_is_accessible() helper to include/linux/mm.h which makes it
available for general use. While here, this replaces all remaining open
encodings for VMA access check with vma_is_accessible().
Cc: Guo Ren <guoren@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: linux-kernel@vger.kernel.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-mips@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-sh@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
arch/csky/mm/fault.c | 2 +-
arch/m68k/mm/fault.c | 2 +-
arch/mips/mm/fault.c | 2 +-
arch/powerpc/mm/fault.c | 2 +-
arch/sh/mm/fault.c | 2 +-
arch/x86/mm/fault.c | 2 +-
include/linux/mm.h | 5 +++++
kernel/sched/fair.c | 2 +-
mm/gup.c | 2 +-
mm/memory.c | 5 -----
mm/mempolicy.c | 3 +--
11 files changed, 14 insertions(+), 15 deletions(-)
diff --git a/arch/csky/mm/fault.c b/arch/csky/mm/fault.c
index f76618b630f9..4b3511b8298d 100644
--- a/arch/csky/mm/fault.c
+++ b/arch/csky/mm/fault.c
@@ -137,7 +137,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
} else {
- if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
+ if (!vma_is_accessible(vma))
goto bad_area;
}
diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
index e9b1d7585b43..d5131ec5d923 100644
--- a/arch/m68k/mm/fault.c
+++ b/arch/m68k/mm/fault.c
@@ -125,7 +125,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
case 1: /* read, present */
goto acc_err;
case 0: /* read, not present */
- if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
+ if (!vma_is_accessible(vma))
goto acc_err;
}
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index 1e8d00793784..5b9f947bfa32 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -142,7 +142,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
goto bad_area;
}
} else {
- if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
+ if (!vma_is_accessible(vma))
goto bad_area;
}
}
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 8db0507619e2..71a3658c516b 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -314,7 +314,7 @@ static bool access_error(bool is_write, bool is_exec,
return false;
}
- if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
+ if (unlikely(!vma_is_accessible(vma)))
return true;
/*
* We should ideally do the vma pkey access check here. But in the
diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 5f51456f4fc7..a8c4253f37d7 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -355,7 +355,7 @@ static inline int access_error(int error_code, struct vm_area_struct *vma)
return 1;
/* read, not present: */
- if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
+ if (unlikely(!vma_is_accessible(vma)))
return 1;
return 0;
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index fa4ea09593ab..c461eaab0306 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1200,7 +1200,7 @@ access_error(unsigned long error_code, struct vm_area_struct *vma)
return 1;
/* read, not present: */
- if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
+ if (unlikely(!vma_is_accessible(vma)))
return 1;
return 0;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 52269e56c514..b0e53ef13ff1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -541,6 +541,11 @@ static inline bool vma_is_anonymous(struct vm_area_struct *vma)
return !vma->vm_ops;
}
+static inline bool vma_is_accessible(struct vm_area_struct *vma)
+{
+ return vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC);
+}
+
#ifdef CONFIG_SHMEM
/*
* The vma_is_shmem is not inline because it is used only by slow
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index fe4e0d775375..6ce54d57dd09 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2573,7 +2573,7 @@ static void task_numa_work(struct callback_head *work)
* Skip inaccessible VMAs to avoid any confusion between
* PROT_NONE and NUMA hinting ptes
*/
- if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
+ if (!vma_is_accessible(vma))
continue;
do {
diff --git a/mm/gup.c b/mm/gup.c
index 1b521e0ac1de..c8ffe2e61f03 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1171,7 +1171,7 @@ long populate_vma_page_range(struct vm_area_struct *vma,
* We want mlock to succeed for regions that have any permissions
* other than PROT_NONE.
*/
- if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
+ if (vma_is_accessible(vma))
gup_flags |= FOLL_FORCE;
/*
diff --git a/mm/memory.c b/mm/memory.c
index 0bccc622e482..2f07747612b7 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3942,11 +3942,6 @@ static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
return VM_FAULT_FALLBACK;
}
-static inline bool vma_is_accessible(struct vm_area_struct *vma)
-{
- return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
-}
-
static vm_fault_t create_huge_pud(struct vm_fault *vmf)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 977c641f78cf..91c1ad6ab8ea 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -649,8 +649,7 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
if (flags & MPOL_MF_LAZY) {
/* Similar to task_numa_work, skip inaccessible VMAs */
- if (!is_vm_hugetlb_page(vma) &&
- (vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)) &&
+ if (!is_vm_hugetlb_page(vma) && vma_is_accessible(vma) &&
!(vma->vm_flags & VM_MIXEDMAP))
change_prot_numa(vma, start, endvma);
return 1;
--
2.20.1
^ permalink raw reply related
* [PATCH 0/5] mm/vma: Use available wrappers when possible
From: Anshuman Khandual @ 2020-02-17 5:03 UTC (permalink / raw)
To: linux-mm, linux-kernel
Cc: linux-arch, linux-sh, Anshuman Khandual, linux-mips, kvm-ppc,
linux-m68k, linux-fsdevel, linuxppc-dev
Apart from adding a VMA flag readable name for trace purpose, this series
does some open encoding replacements with availabe VMA specific wrappers.
This skips VM_HUGETLB check in vma_migratable() as its already being done
with another patch (https://patchwork.kernel.org/patch/11347831/) which
is yet to be merged.
This series applies on 5.6-rc2. This has been build tested on multiple
platforms, though boot and runtime testing was limited to arm64 and x86.
Cc: linux-kernel@vger.kernel.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-mips@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-sh@vger.kernel.org
Cc: kvm-ppc@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Anshuman Khandual (5):
mm/vma: Add missing VMA flag readable name for VM_SYNC
mm/vma: Make vma_is_accessible() available for general use
mm/vma: Replace all remaining open encodings with is_vm_hugetlb_page()
mm/vma: Replace all remaining open encodings with vma_set_anonymous()
mm/vma: Replace all remaining open encodings with vma_is_anonymous()
arch/csky/mm/fault.c | 2 +-
arch/m68k/mm/fault.c | 2 +-
arch/mips/mm/fault.c | 2 +-
arch/powerpc/kvm/e500_mmu_host.c | 2 +-
arch/powerpc/mm/fault.c | 2 +-
arch/sh/mm/fault.c | 2 +-
arch/x86/mm/fault.c | 2 +-
drivers/misc/mic/scif/scif_mmap.c | 2 +-
fs/binfmt_elf.c | 2 +-
include/asm-generic/tlb.h | 2 +-
include/linux/mm.h | 5 +++++
include/trace/events/mmflags.h | 1 +
kernel/events/core.c | 3 ++-
kernel/sched/fair.c | 2 +-
mm/gup.c | 5 +++--
mm/memory.c | 5 -----
mm/mempolicy.c | 3 +--
17 files changed, 23 insertions(+), 21 deletions(-)
--
2.20.1
^ permalink raw reply
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