Re: [PATCH v3 1/7] capabilities: introduce CAP_SYS_PERFMON to kernel and user space
From: Stephen Smalley <hidden>
Date: 2019-12-17 15:02:51
Also in:
bpf, intel-gfx, linux-perf-users, linux-security-module, lkml, selinux
On 12/16/19 2:58 PM, Alexey Budankov wrote:
quoted hunk ↗ jump to hunk
Introduce CAP_SYS_PERFMON capability devoted to secure system performance monitoring and observability so that CAP_SYS_PERFMON would assist CAP_SYS_ADMIN capability in its governing role for perf_events, i915_perf and other subsystems of the kernel. CAP_SYS_PERFMON intends to harden system security and integrity during system performance monitoring and observability by decreasing attack surface that is available to CAP_SYS_ADMIN privileged processes. CAP_SYS_PERFMON intends to take over CAP_SYS_ADMIN credentials related to system performance monitoring and observability and balance amount of CAP_SYS_ADMIN credentials in accordance with the recommendations provided in the man page for CAP_SYS_ADMIN [1]: "Note: this capability is overloaded; see Notes to kernel developers, below." [1] http://man7.org/linux/man-pages/man7/capabilities.7.html Signed-off-by: Alexey Budankov <redacted> --- include/linux/capability.h | 1 + include/uapi/linux/capability.h | 8 +++++++- security/selinux/include/classmap.h | 4 ++-- 3 files changed, 10 insertions(+), 3 deletions(-)diff --git a/include/linux/capability.h b/include/linux/capability.h index ecce0f43c73a..6342502c4c2a 100644 --- a/include/linux/capability.h +++ b/include/linux/capability.h@@ -251,6 +251,7 @@ 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); +#define perfmon_capable() (capable(CAP_SYS_PERFMON) || capable(CAP_SYS_ADMIN))
I think making it a static inline bool function instead of a macro would be preferred? Otherwise, Acked-by: Stephen Smalley <redacted>
quoted hunk ↗ jump to hunk
/* 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 240fdb9a60f6..98e03cc76c7c 100644 --- a/include/uapi/linux/capability.h +++ b/include/uapi/linux/capability.h@@ -366,8 +366,14 @@ 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_SYS_PERFMON 38 -#define CAP_LAST_CAP CAP_AUDIT_READ +#define CAP_LAST_CAP CAP_SYS_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 7db24855e12d..bae602c623b0 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", "sys_perfmon" -#if CAP_LAST_CAP > CAP_AUDIT_READ +#if CAP_LAST_CAP > CAP_SYS_PERFMON #error New capability defined, please update COMMON_CAP2_PERMS. #endif