BACKPORT: perf_event: Add support for LSM and SELinux checks

arch/powerpc/perf/core-book3s.c

@@ -96,7 +96,7 @@ static inline unsigned long perf_ip_adjust(struct pt_regs *regs)
 {
 	return 0;
 }
-static inline void perf_get_data_addr(struct pt_regs *regs, u64 *addrp) { }
+static inline void perf_get_data_addr(struct perf_event *event, struct pt_regs *regs, u64 *addrp) { }
 static inline u32 perf_get_misc_flags(struct pt_regs *regs)
 {
 	return 0;
@@ -127,7 +127,7 @@ static unsigned long ebb_switch_in(bool ebb, struct cpu_hw_events *cpuhw)
 static inline void power_pmu_bhrb_enable(struct perf_event *event) {}
 static inline void power_pmu_bhrb_disable(struct perf_event *event) {}
 static void power_pmu_sched_task(struct perf_event_context *ctx, bool sched_in) {}
-static inline void power_pmu_bhrb_read(struct cpu_hw_events *cpuhw) {}
+static inline void power_pmu_bhrb_read(struct perf_event *event, struct cpu_hw_events *cpuhw) {}
 static void pmao_restore_workaround(bool ebb) { }
 #endif /* CONFIG_PPC32 */
 
@@ -179,7 +179,7 @@ static inline unsigned long perf_ip_adjust(struct pt_regs *regs)
  * pointed to by SIAR; this is indicated by the [POWER6_]MMCRA_SDSYNC, the
  * [POWER7P_]MMCRA_SDAR_VALID bit in MMCRA, or the SDAR_VALID bit in SIER.
  */
-static inline void perf_get_data_addr(struct pt_regs *regs, u64 *addrp)
+static inline void perf_get_data_addr(struct perf_event *event, struct pt_regs *regs, u64 *addrp)
 {
 	unsigned long mmcra = regs->dsisr;
 	bool sdar_valid;
@@ -204,8 +204,7 @@ static inline void perf_get_data_addr(struct pt_regs *regs, u64 *addrp)
 	if (!(mmcra & MMCRA_SAMPLE_ENABLE) || sdar_valid)
 		*addrp = mfspr(SPRN_SDAR);
 
-	if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN) &&
-		is_kernel_addr(mfspr(SPRN_SDAR)))
+	if (is_kernel_addr(mfspr(SPRN_SDAR)) && perf_allow_kernel(&event->attr) != 0)
 		*addrp = 0;
 }
 
@@ -444,7 +443,7 @@ static __u64 power_pmu_bhrb_to(u64 addr)
 }
 
 /* Processing BHRB entries */
-static void power_pmu_bhrb_read(struct cpu_hw_events *cpuhw)
+static void power_pmu_bhrb_read(struct perf_event *event, struct cpu_hw_events *cpuhw)
 {
 	u64 val;
 	u64 addr;
@@ -472,8 +471,7 @@ static void power_pmu_bhrb_read(struct cpu_hw_events *cpuhw)
 			 * exporting it to userspace (avoid exposure of regions
 			 * where we could have speculative execution)
 			 */
-			if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN) &&
-				is_kernel_addr(addr))
+			if (is_kernel_addr(addr) && perf_allow_kernel(&event->attr) != 0)
 				continue;
 
 			/* Branches are read most recent first (ie. mfbhrb 0 is
@@ -2096,12 +2094,12 @@ static void record_and_restart(struct perf_event *event, unsigned long val,
 
 		if (event->attr.sample_type &
 		    (PERF_SAMPLE_ADDR | PERF_SAMPLE_PHYS_ADDR))
-			perf_get_data_addr(regs, &data.addr);
+			perf_get_data_addr(event, regs, &data.addr);
 
 		if (event->attr.sample_type & PERF_SAMPLE_BRANCH_STACK) {
 			struct cpu_hw_events *cpuhw;
 			cpuhw = this_cpu_ptr(&cpu_hw_events);
-			power_pmu_bhrb_read(cpuhw);
+			power_pmu_bhrb_read(event, cpuhw);
 			data.br_stack = &cpuhw->bhrb_stack;
 		}
 

arch/x86/events/intel/bts.c

@@ -555,9 +555,11 @@ static int bts_event_init(struct perf_event *event)
 	 * Note that the default paranoia setting permits unprivileged
 	 * users to profile the kernel.
 	 */
-	if (event->attr.exclude_kernel && perf_paranoid_kernel() &&
-	    !capable(CAP_SYS_ADMIN))
-		return -EACCES;
+	if (event->attr.exclude_kernel) {
+		ret = perf_allow_kernel(&event->attr);
+		if (ret)
+			return ret;
+	}
 
 	if (x86_add_exclusive(x86_lbr_exclusive_bts))
 		return -EBUSY;

arch/x86/events/intel/core.c

@@ -3315,8 +3315,9 @@ static int intel_pmu_hw_config(struct perf_event *event)
 	if (x86_pmu.version < 3)
 		return -EINVAL;
 
-	if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
-		return -EACCES;
+	ret = perf_allow_cpu(&event->attr);
+	if (ret)
+		return ret;
 
 	event->hw.config |= ARCH_PERFMON_EVENTSEL_ANY;
 

arch/x86/events/intel/p4.c

@@ -776,8 +776,9 @@ static int p4_validate_raw_event(struct perf_event *event)
 	 * the user needs special permissions to be able to use it
 	 */
 	if (p4_ht_active() && p4_event_bind_map[v].shared) {
-		if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
-			return -EACCES;
+		v = perf_allow_cpu(&event->attr);
+		if (v)
+			return v;
 	}
 
 	/* ESCR EventMask bits may be invalid */

include/linux/lsm_hooks.h

@@ -1818,6 +1818,14 @@ union security_list_options {
 	void (*bpf_prog_free_security)(struct bpf_prog_aux *aux);
 #endif /* CONFIG_BPF_SYSCALL */
 	int (*locked_down)(enum lockdown_reason what);
+#ifdef CONFIG_PERF_EVENTS
+	int (*perf_event_open)(struct perf_event_attr *attr, int type);
+	int (*perf_event_alloc)(struct perf_event *event);
+	void (*perf_event_free)(struct perf_event *event);
+	int (*perf_event_read)(struct perf_event *event);
+	int (*perf_event_write)(struct perf_event *event);
+
+#endif
 };
 
 struct security_hook_heads {
@@ -2060,6 +2068,13 @@ struct security_hook_heads {
 	struct hlist_head bpf_prog_free_security;
 #endif /* CONFIG_BPF_SYSCALL */
 	struct hlist_head locked_down;
+#ifdef CONFIG_PERF_EVENTS
+	struct hlist_head perf_event_open;
+	struct hlist_head perf_event_alloc;
+	struct hlist_head perf_event_free;
+	struct hlist_head perf_event_read;
+	struct hlist_head perf_event_write;
+#endif
 } __randomize_layout;
 
 /*

include/linux/perf_event.h

@@ -56,6 +56,7 @@ struct perf_guest_info_callbacks {
 #include <linux/perf_regs.h>
 #include <linux/cgroup.h>
 #include <linux/refcount.h>
+#include <linux/security.h>
 #include <asm/local.h>
 
 struct perf_callchain_entry {
@@ -721,6 +722,9 @@ struct perf_event {
 	struct perf_cgroup		*cgrp; /* cgroup event is attach to */
 #endif
 
+#ifdef CONFIG_SECURITY
+	void *security;
+#endif
 	struct list_head		sb_list;
 #endif /* CONFIG_PERF_EVENTS */
 };
@@ -1241,24 +1245,46 @@ extern int perf_cpu_time_max_percent_handler(struct ctl_table *table, int write,
 int perf_event_max_stack_handler(struct ctl_table *table, int write,
 				 void __user *buffer, size_t *lenp, loff_t *ppos);
 
+/* Access to perf_event_open(2) syscall. */
+#define PERF_SECURITY_OPEN		0
+
+/* Finer grained perf_event_open(2) access control. */
+#define PERF_SECURITY_CPU		1
+#define PERF_SECURITY_KERNEL		2
+#define PERF_SECURITY_TRACEPOINT	3
+
 static inline bool perf_paranoid_any(void)
 {
 	return sysctl_perf_event_paranoid > 2;
 }
 
-static inline bool perf_paranoid_tracepoint_raw(void)
+static inline int perf_is_paranoid(void)
 {
 	return sysctl_perf_event_paranoid > -1;
 }
 
-static inline bool perf_paranoid_cpu(void)
+static inline int perf_allow_kernel(struct perf_event_attr *attr)
 {
-	return sysctl_perf_event_paranoid > 0;
+	if (sysctl_perf_event_paranoid > 1 && !capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	return security_perf_event_open(attr, PERF_SECURITY_KERNEL);
 }
 
-static inline bool perf_paranoid_kernel(void)
+static inline int perf_allow_cpu(struct perf_event_attr *attr)
 {
-	return sysctl_perf_event_paranoid > 1;
+	if (sysctl_perf_event_paranoid > 0 && !capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	return security_perf_event_open(attr, PERF_SECURITY_CPU);
+}
+
+static inline int perf_allow_tracepoint(struct perf_event_attr *attr)
+{
+	if (sysctl_perf_event_paranoid > -1 && !capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	return security_perf_event_open(attr, PERF_SECURITY_TRACEPOINT);
 }
 
 extern void perf_event_init(void);

include/linux/security.h

@@ -1897,4 +1897,42 @@ static inline void security_bpf_prog_free(struct bpf_prog_aux *aux)
 #endif /* CONFIG_SECURITY */
 #endif /* CONFIG_BPF_SYSCALL */
 
+#ifdef CONFIG_PERF_EVENTS
+struct perf_event_attr;
+struct perf_event;
+
+#ifdef CONFIG_SECURITY
+extern int security_perf_event_open(struct perf_event_attr *attr, int type);
+extern int security_perf_event_alloc(struct perf_event *event);
+extern void security_perf_event_free(struct perf_event *event);
+extern int security_perf_event_read(struct perf_event *event);
+extern int security_perf_event_write(struct perf_event *event);
+#else
+static inline int security_perf_event_open(struct perf_event_attr *attr,
+					   int type)
+{
+	return 0;
+}
+
+static inline int security_perf_event_alloc(struct perf_event *event)
+{
+	return 0;
+}
+
+static inline void security_perf_event_free(struct perf_event *event)
+{
+}
+
+static inline int security_perf_event_read(struct perf_event *event)
+{
+	return 0;
+}
+
+static inline int security_perf_event_write(struct perf_event *event)
+{
+	return 0;
+}
+#endif /* CONFIG_SECURITY */
+#endif /* CONFIG_PERF_EVENTS */
+
 #endif /* ! __LINUX_SECURITY_H */

kernel/events/core.c

@@ -4248,8 +4248,9 @@ find_get_context(struct pmu *pmu, struct task_struct *task,
 
 	if (!task) {
 		/* Must be root to operate on a CPU event: */
-		if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
-			return ERR_PTR(-EACCES);
+		err = perf_allow_cpu(&event->attr);
+		if (err)
+			return ERR_PTR(err);
 
 		cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
 		ctx = &cpuctx->ctx;
@@ -4558,6 +4559,8 @@ static void _free_event(struct perf_event *event)
 
 	unaccount_event(event);
 
+	security_perf_event_free(event);
+
 	if (event->rb) {
 		/*
 		 * Can happen when we close an event with re-directed output.
@@ -5011,6 +5014,10 @@ perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 	struct perf_event_context *ctx;
 	int ret;
 
+	ret = security_perf_event_read(event);
+	if (ret)
+		return ret;
+
 	ctx = perf_event_ctx_lock(event);
 	ret = __perf_read(event, buf, count);
 	perf_event_ctx_unlock(event, ctx);
@@ -5275,6 +5282,11 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	struct perf_event_context *ctx;
 	long ret;
 
+	/* Treat ioctl like writes as it is likely a mutating operation. */
+	ret = security_perf_event_write(event);
+	if (ret)
+		return ret;
+
 	ctx = perf_event_ctx_lock(event);
 	ret = _perf_ioctl(event, cmd, arg);
 	perf_event_ctx_unlock(event, ctx);
@@ -5739,6 +5751,10 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 	if (!(vma->vm_flags & VM_SHARED))
 		return -EINVAL;
 
+	ret = security_perf_event_read(event);
+	if (ret)
+		return ret;
+
 	vma_size = vma->vm_end - vma->vm_start;
 
 	if (vma->vm_pgoff == 0) {
@@ -5872,7 +5888,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 	lock_limit >>= PAGE_SHIFT;
 	locked = atomic64_read(&vma->vm_mm->pinned_vm) + extra;
 
-	if ((locked > lock_limit) && perf_paranoid_tracepoint_raw() &&
+	if ((locked > lock_limit) && perf_is_paranoid() &&
 		!capable(CAP_IPC_LOCK)) {
 		ret = -EPERM;
 		goto unlock;
@@ -10623,11 +10639,20 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 		}
 	}
 
+	err = security_perf_event_alloc(event);
+	if (err)
+		goto err_callchain_buffer;
+
 	/* symmetric to unaccount_event() in _free_event() */
 	account_event(event);
 
 	return event;
 
+err_callchain_buffer:
+	if (!event->parent) {
+		if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
+			put_callchain_buffers();
+	}
 err_addr_filters:
 	kfree(event->addr_filter_ranges);
 
@@ -10716,9 +10741,11 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
 			attr->branch_sample_type = mask;
 		}
 		/* privileged levels capture (kernel, hv): check permissions */
-		if ((mask & PERF_SAMPLE_BRANCH_PERM_PLM)
-		    && perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
-			return -EACCES;
+		if (mask & PERF_SAMPLE_BRANCH_PERM_PLM) {
+			ret = perf_allow_kernel(attr);
+			if (ret)
+				return ret;
+		}
 	}
 
 	if (attr->sample_type & PERF_SAMPLE_REGS_USER) {
@@ -10933,13 +10960,19 @@ int ksys_perf_event_open(struct perf_event_attr __user * attr_uptr, pid_t pid,
 	if (perf_paranoid_any() && !capable(CAP_SYS_ADMIN))
 		return -EACCES;
 
+	/* Do we allow access to perf_event_open(2) ? */
+	err = security_perf_event_open(&attr, PERF_SECURITY_OPEN);
+	if (err)
+		return err;
+
 	err = perf_copy_attr(attr_uptr, &attr);
 	if (err)
 		return err;
 
 	if (!attr.exclude_kernel) {
-		if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
-			return -EACCES;
+		err = perf_allow_kernel(&attr);
+		if (err)
+			return err;
 	}
 
 	if (attr.namespaces) {
@@ -10956,9 +10989,11 @@ int ksys_perf_event_open(struct perf_event_attr __user * attr_uptr, pid_t pid,
 	}
 
 	/* Only privileged users can get physical addresses */
-	if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR) &&
-	    perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
-		return -EACCES;
+	if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR)) {
+		err = perf_allow_kernel(&attr);
+		if (err)
+			return err;
+	}
 
 	err = security_locked_down(LOCKDOWN_PERF);
 	if (err && (attr.sample_type & PERF_SAMPLE_REGS_INTR))