[PATCH 05/60] capabilities: Introduce CAP_PERFMON to kernel and user space

[PATCH 05/60] capabilities: Introduce CAP_PERFMON to kernel and user space

[Arnaldo Carvalho de Melo]

From: Alexey Budankov <alexey.budankov@linux.intel.com>

Introduce the CAP_PERFMON capability designed to secure system
performance monitoring and observability operations so that CAP_PERFMON
can 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 principle 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 applicability and scalability
of system performance monitoring and observability operations beyond 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 capability
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>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/5590d543-82c6-490a-6544-08e6a5517db0@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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
 
-- 
2.21.1

[PATCH 06/60] perf/core: Open access to the core for CAP_PERFMON privileged process

[Arnaldo Carvalho de Melo]

From: Alexey Budankov <alexey.budankov@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 principle 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 the 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>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: linux-man@vger.kernel.org
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/471acaef-bb8a-5ce2-923f-90606b78eef9@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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 9c3e7619c929..87e21681759c 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1305,7 +1305,7 @@ 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);
@@ -1313,7 +1313,7 @@ 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);
@@ -1321,7 +1321,7 @@ 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 bc9b98a9af9a..74025b7b83a0 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11504,7 +11504,7 @@ SYSCALL_DEFINE5(perf_event_open,
 	}
 
 	if (attr.namespaces) {
-		if (!capable(CAP_SYS_ADMIN))
+		if (!perfmon_capable())
 			return -EACCES;
 	}
 
-- 
2.21.1

[PATCH 07/60] perf/core: open access to probes for CAP_PERFMON privileged process

[Arnaldo Carvalho de Melo]

From: Alexey Budankov <alexey.budankov@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 principle 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>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Cc: linux-man@vger.kernel.org
Link: http://lore.kernel.org/lkml/3c129d9a-ba8a-3483-ecc5-ad6c8e7c203f@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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 74025b7b83a0..52951e9e8e1b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9397,7 +9397,7 @@ 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;
 
 	/*
@@ -9457,7 +9457,7 @@ 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;
 
 	/*
-- 
2.21.1

[PATCH 08/60] perf tools: Support CAP_PERFMON capability

[Arnaldo Carvalho de Melo]

From: Alexey Budankov <alexey.budankov@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 operations. Make
perf_event_paranoid_check() and __cmd_ftrace() to be aware of
CAP_PERFMON capability.

CAP_PERFMON implements the principle 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.

Committer testing:

Using a libcap with this patch:

  diff --git a/libcap/include/uapi/linux/capability.h b/libcap/include/uapi/linux/capability.h
  index 78b2fd4c8a95..89b5b0279b60 100644
  --- a/libcap/include/uapi/linux/capability.h
  +++ b/libcap/include/uapi/linux/capability.h
  @@ -366,8 +366,9 @@ struct vfs_ns_cap_data {

   #define CAP_AUDIT_READ       37

  +#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)

Note that using '38' in place of 'cap_perfmon' works to some degree with
an old libcap, its only when cap_get_flag() is called that libcap
performs an error check based on the maximum value known for
capabilities that it will fail.

This makes determining the default of perf_event_attr.exclude_kernel to
fail, as it can't determine if CAP_PERFMON is in place.

Using 'perf top -e cycles' avoids the default check and sets
perf_event_attr.exclude_kernel to 1.

As root, with a libcap supporting CAP_PERFMON:

  # groupadd perf_users
  # adduser perf -g perf_users
  # mkdir ~perf/bin
  # cp ~acme/bin/perf ~perf/bin/
  # chgrp perf_users ~perf/bin/perf
  # setcap "cap_perfmon,cap_sys_ptrace,cap_syslog=ep" ~perf/bin/perf
  # getcap ~perf/bin/perf
  /home/perf/bin/perf = cap_sys_ptrace,cap_syslog,cap_perfmon+ep
  # ls -la ~perf/bin/perf
  -rwxr-xr-x. 1 root perf_users 16968552 Apr  9 13:10 /home/perf/bin/perf

As the 'perf' user in the 'perf_users' group:

  $ perf top -a --stdio
  Error:
  Failed to mmap with 1 (Operation not permitted)
  $

Either add the cap_ipc_lock capability to the perf binary or reduce the
ring buffer size to some smaller value:

  $ perf top -m10 -a --stdio
  rounding mmap pages size to 64K (16 pages)
  Error:
  Failed to mmap with 1 (Operation not permitted)
  $ perf top -m4 -a --stdio
  Error:
  Failed to mmap with 1 (Operation not permitted)
  $ perf top -m2 -a --stdio
   PerfTop: 762 irqs/sec  kernel:49.7%  exact: 100.0% lost: 0/0 drop: 0/0 [4000Hz cycles], (all, 4 CPUs)
  ------------------------------------------------------------------------------------------------------

     9.83%  perf                [.] __symbols__insert
     8.58%  perf                [.] rb_next
     5.91%  [kernel]            [k] module_get_kallsym
     5.66%  [kernel]            [k] kallsyms_expand_symbol.constprop.0
     3.98%  libc-2.29.so        [.] __GI_____strtoull_l_internal
     3.66%  perf                [.] rb_insert_color
     2.34%  [kernel]            [k] vsnprintf
     2.30%  [kernel]            [k] string_nocheck
     2.16%  libc-2.29.so        [.] _IO_getdelim
     2.15%  [kernel]            [k] number
     2.13%  [kernel]            [k] format_decode
     1.58%  libc-2.29.so        [.] _IO_feof
     1.52%  libc-2.29.so        [.] __strcmp_avx2
     1.50%  perf                [.] rb_set_parent_color
     1.47%  libc-2.29.so        [.] __libc_calloc
     1.24%  [kernel]            [k] do_syscall_64
     1.17%  [kernel]            [k] __x86_indirect_thunk_rax

  $ perf record -a sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.552 MB perf.data (74 samples) ]
  $ perf evlist
  cycles
  $ perf evlist -v
  cycles: size: 120, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD, read_format: ID, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1, task: 1, precise_ip: 3, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1
  $ perf report | head -20
  # To display the perf.data header info, please use --header/--header-only options.
  #
  #
  # Total Lost Samples: 0
  #
  # Samples: 74  of event 'cycles'
  # Event count (approx.): 15694834
  #
  # Overhead  Command          Shared Object               Symbol
  # ........  ...............  ..........................  ......................................
  #
      19.62%  perf             [kernel.vmlinux]            [k] strnlen_user
      13.88%  swapper          [kernel.vmlinux]            [k] intel_idle
      13.83%  ksoftirqd/0      [kernel.vmlinux]            [k] pfifo_fast_dequeue
      13.51%  swapper          [kernel.vmlinux]            [k] kmem_cache_free
       6.31%  gnome-shell      [kernel.vmlinux]            [k] kmem_cache_free
       5.66%  kworker/u8:3+ix  [kernel.vmlinux]            [k] delay_tsc
       4.42%  perf             [kernel.vmlinux]            [k] __set_cpus_allowed_ptr
       3.45%  kworker/2:1-eve  [kernel.vmlinux]            [k] shmem_truncate_range
       2.29%  gnome-shell      libgobject-2.0.so.0.6000.7  [.] g_closure_ref
  $

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/a66d5648-2b8e-577e-e1f2-1d56c017ab5e@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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 eb880efbce16..d23db6755f51 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2523,14 +2523,14 @@ 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 d707c9624dd9..37a9492edb3e 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -290,6 +290,7 @@ 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;
 }
 
-- 
2.21.1

[PATCH 09/60] drm/i915/perf: Open access for CAP_PERFMON privileged process

[Arnaldo Carvalho de Melo]

From: Alexey Budankov <alexey.budankov@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 principle 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>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/e3e3292f-f765-ea98-e59c-fbe2db93fd34@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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 551be589d6f4..5fb174931231 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -3433,10 +3433,10 @@ 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;
@@ -3629,9 +3629,8 @@ 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;
 			}
@@ -4052,7 +4051,7 @@ 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;
 	}
@@ -4199,7 +4198,7 @@ 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;
 	}
-- 
2.21.1

[PATCH 10/60] trace/bpf_trace: Open access for CAP_PERFMON privileged process

[Arnaldo Carvalho de Melo]

From: Alexey Budankov <alexey.budankov@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 principle 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>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/c0a0ae47-8b6e-ff3e-416b-3cd1faaf71c0@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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 ca1796747a77..d7d88007dc6d 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1468,7 +1468,7 @@ 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;
-- 
2.21.1

[PATCH 11/60] powerpc/perf: open access for CAP_PERFMON privileged process

[Arnaldo Carvalho de Melo]

From: Alexey Budankov <alexey.budankov@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 principle 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>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/ac98cd9f-b59e-673c-c70d-180b3e7695d2@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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 eb82dda884e5..0edcfd0b491d 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -976,7 +976,7 @@ 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 */
@@ -1412,7 +1412,7 @@ 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 */
-- 
2.21.1

[PATCH 12/60] parisc/perf: open access for CAP_PERFMON privileged process

[Arnaldo Carvalho de Melo]

From: Alexey Budankov <alexey.budankov@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 principle 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>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Helge Deller <deller@gmx.de>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/8cc98809-d35b-de0f-de02-4cf554f3cf62@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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))
-- 
2.21.1

[PATCH 13/60] drivers/perf: Open access for CAP_PERFMON privileged process

[Arnaldo Carvalho de Melo]

From: Alexey Budankov <alexey.budankov@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 principle 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>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Will Deacon <will@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/4ec1d6f7-548c-8d1c-f84a-cebeb9674e4e@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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 b72c04852599..0e0961a2b405 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))))
-- 
2.21.1

[PATCH 14/60] drivers/oprofile: Open access for CAP_PERFMON privileged process

[Arnaldo Carvalho de Melo]

From: Alexey Budankov <alexey.budankov@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 principle 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>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/691f1096-b15f-9b12-50a0-c2b93918149e@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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))
-- 
2.21.1

[PATCH 15/60] doc/admin-guide: Update perf-security.rst with CAP_PERFMON information

[Arnaldo Carvalho de Melo]

From: Alexey Budankov <alexey.budankov@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.

Committer notes:

While testing 'perf top' under cap_perfmon I noticed that it needs
some more capability and Alexey pointed out cap_ipc_lock, as needed by
this kernel chunk:

  kernel/events/core.c: 6101
       if ((locked > lock_limit) && perf_is_paranoid() &&
               !capable(CAP_IPC_LOCK)) {
               ret = -EPERM;
               goto unlock;
       }

So I added it to the documentation, and also mentioned that if the
libcap version doesn't yet supports 'cap_perfmon', its numeric value can
be used instead, i.e. if:

	# setcap "cap_perfmon,cap_ipc_lock,cap_sys_ptrace,cap_syslog=ep" perf

Fails, try:

	# setcap "38,cap_ipc_lock,cap_sys_ptrace,cap_syslog=ep" perf

I also added a paragraph stating that using an unpatched libcap will
fail the check for CAP_PERFMON, as it checks the cap number against a
maximum to see if it is valid, which makes it use as the default the
'cycles:u' event, even tho a cap_perfmon capable perf binary can get
kernel samples, to workaround that just use, e.g.:

  # perf top -e cycles
  # perf record -e cycles

And it will sample kernel and user modes.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/17278551-9399-9ebe-d665-8827016a217d@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 Documentation/admin-guide/perf-security.rst | 86 +++++++++++++++------
 1 file changed, 61 insertions(+), 25 deletions(-)

diff --git a/Documentation/admin-guide/perf-security.rst b/Documentation/admin-guide/perf-security.rst
index 72effa7c23b9..1307b5274a0f 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 are
+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 principle of least
+privilege [13]_ (POSIX 1003.1e: 2.2.2.39) for performance monitoring and
+observability operations in the kernel and provides a secure approach to
+perfomance monitoring and observability in the system.
+
+For backward compatibility reasons the 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 the 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 +122,51 @@ 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
+
+If the libcap installed doesn't yet support "cap_perfmon", use "38" instead,
+i.e.:
+
+::
+
+   # setcap "38,cap_ipc_lock,cap_sys_ptrace,cap_syslog=ep" perf
+
+Note that you may need to have 'cap_ipc_lock' in the mix for tools such as
+'perf top', alternatively use 'perf top -m N', to reduce the memory that
+it uses for the perf ring buffer, see the memory allocation section below.
+
+Using a libcap without support for CAP_PERFMON will make cap_get_flag(caps, 38,
+CAP_EFFECTIVE, &val) fail, which will lead the default event to be 'cycles:u',
+so as a workaround explicitly ask for the 'cycles' event, i.e.:
+
+::
+
+  # perf top -e cycles
+
+To get kernel and user samples with a perf binary with just CAP_PERFMON.
 
 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 +201,7 @@ 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 +262,5 @@ 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>`_
-- 
2.21.1

[PATCH 16/60] doc/admin-guide: update kernel.rst with CAP_PERFMON information

[Arnaldo Carvalho de Melo]

From: Alexey Budankov <alexey.budankov@linux.intel.com>

Update the 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>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/84c32383-14a2-fa35-16b6-f9e59bd37240@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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 39c95c0e13d3..7e4c28dfc9ca 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -730,7 +730,13 @@ 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.
@@ -739,13 +745,13 @@ users (without CAP_SYS_ADMIN).  The default value is 2.
      ``CAP_IPC_LOCK``.
 
 >=0  Disallow ftrace function tracepoint by users without
-     ``CAP_SYS_ADMIN``.
+     ``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``.
 ===  ==================================================================
 
 
-- 
2.21.1