[v7,01/12] capabilities: introduce CAP_PERFMON to kernel and user space
diff mbox series

Message ID f56fbb5c-1477-44d5-7346-85a1ca0869dc@linux.intel.com
State New
Headers show
Series
  • Introduce CAP_PERFMON to secure system performance monitoring and observability
Related show

Commit Message

Alexey Budankov Feb. 17, 2020, 8:06 a.m. UTC
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(-)

Comments

Stephen Smalley Feb. 18, 2020, 6:22 p.m. UTC | #1
On 2/17/20 3:06 AM, Alexey Budankov wrote:
> 
> 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>

Acked-by: Stephen Smalley <sds@tycho.nsa.gov>

[...]
James Morris Feb. 18, 2020, 7:21 p.m. UTC | #2
On Mon, 17 Feb 2020, Alexey Budankov wrote:

> 
> 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.


Acked-by: James Morris <jamorris@linux.microsoft.com>
Alexey Budankov Feb. 19, 2020, 7:54 a.m. UTC | #3
On 18.02.2020 22:21, James Morris wrote:
> On Mon, 17 Feb 2020, Alexey Budankov wrote:
> 
>>
>> 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.
> 
> 
> Acked-by: James Morris <jamorris@linux.microsoft.com>

Thanks James! 
I appreciate your involvement and collaboration 
w.r.t to the whole patch set.

Gratefully,
Alexey

Patch
diff mbox series

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