kernel/trace/bpf_trace.c - linux - Git at Google

 /* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of version 2 of the GNU General Public
  * License as published by the Free Software Foundation.
  */
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/bpf.h>
 #include <linux/filter.h>
 #include <linux/uaccess.h>
 #include <linux/ctype.h>
 #include "trace.h"

 static DEFINE_PER_CPU(int, bpf_prog_active);

 /**
  * trace_call_bpf - invoke BPF program
  * @prog: BPF program
  * @ctx: opaque context pointer
  *
  * kprobe handlers execute BPF programs via this helper.
  * Can be used from static tracepoints in the future.
  *
  * Return: BPF programs always return an integer which is interpreted by
  * kprobe handler as:
  * 0 - return from kprobe (event is filtered out)
  * 1 - store kprobe event into ring buffer
  * Other values are reserved and currently alias to 1
  */
 unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx)
 {
 	unsigned int ret;

 	if (in_nmi()) /* not supported yet */
 		return 1;

 	preempt_disable();

 	if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
 		/*
 		 * since some bpf program is already running on this cpu,
 		 * don't call into another bpf program (same or different)
 		 * and don't send kprobe event into ring-buffer,
 		 * so return zero here
 		 */
 		ret = 0;
 		goto out;
 	}

 	rcu_read_lock();
 	ret = BPF_PROG_RUN(prog, ctx);
 	rcu_read_unlock();

  out:
 	__this_cpu_dec(bpf_prog_active);
 	preempt_enable();

 	return ret;
 }
 EXPORT_SYMBOL_GPL(trace_call_bpf);

 static u64 bpf_probe_read(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
 {
 	void *dst = (void *) (long) r1;
 	int size = (int) r2;
 	void *unsafe_ptr = (void *) (long) r3;

 	return probe_kernel_read(dst, unsafe_ptr, size);
 }

 static const struct bpf_func_proto bpf_probe_read_proto = {
 	.func		= bpf_probe_read,
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_STACK,
 	.arg2_type	= ARG_CONST_STACK_SIZE,
 	.arg3_type	= ARG_ANYTHING,
 };

 /*
  * limited trace_printk()
  * only %d %u %x %ld %lu %lx %lld %llu %llx %p %s conversion specifiers allowed
  */
 static u64 bpf_trace_printk(u64 r1, u64 fmt_size, u64 r3, u64 r4, u64 r5)
 {
 	char *fmt = (char *) (long) r1;
 	bool str_seen = false;
 	int mod[3] = {};
 	int fmt_cnt = 0;
 	u64 unsafe_addr;
 	char buf[64];
 	int i;

 	/*
 	 * bpf_check()->check_func_arg()->check_stack_boundary()
 	 * guarantees that fmt points to bpf program stack,
 	 * fmt_size bytes of it were initialized and fmt_size > 0
 	 */
 	if (fmt[--fmt_size] != 0)
 		return -EINVAL;

 	/* check format string for allowed specifiers */
 	for (i = 0; i < fmt_size; i++) {
 		if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i]))
 			return -EINVAL;

 		if (fmt[i] != '%')
 			continue;

 		if (fmt_cnt >= 3)
 			return -EINVAL;

 		/* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */
 		i++;
 		if (fmt[i] == 'l') {
 			mod[fmt_cnt]++;
 			i++;
 		} else if (fmt[i] == 'p' || fmt[i] == 's') {
 			mod[fmt_cnt]++;
 			i++;
 			if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0)
 				return -EINVAL;
 			fmt_cnt++;
 			if (fmt[i - 1] == 's') {
 				if (str_seen)
 					/* allow only one '%s' per fmt string */
 					return -EINVAL;
 				str_seen = true;

 				switch (fmt_cnt) {
 				case 1:
 					unsafe_addr = r3;
 					r3 = (long) buf;
 					break;
 				case 2:
 					unsafe_addr = r4;
 					r4 = (long) buf;
 					break;
 				case 3:
 					unsafe_addr = r5;
 					r5 = (long) buf;
 					break;
 				}
 				buf[0] = 0;
 				strncpy_from_unsafe(buf,
 						    (void *) (long) unsafe_addr,
 						    sizeof(buf));
 			}
 			continue;
 		}

 		if (fmt[i] == 'l') {
 			mod[fmt_cnt]++;
 			i++;
 		}

 		if (fmt[i] != 'd' && fmt[i] != 'u' && fmt[i] != 'x')
 			return -EINVAL;
 		fmt_cnt++;
 	}

 	return __trace_printk(1/* fake ip will not be printed */, fmt,
 			      mod[0] == 2 ? r3 : mod[0] == 1 ? (long) r3 : (u32) r3,
 			      mod[1] == 2 ? r4 : mod[1] == 1 ? (long) r4 : (u32) r4,
 			      mod[2] == 2 ? r5 : mod[2] == 1 ? (long) r5 : (u32) r5);
 }

 static const struct bpf_func_proto bpf_trace_printk_proto = {
 	.func		= bpf_trace_printk,
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_STACK,
 	.arg2_type	= ARG_CONST_STACK_SIZE,
 };

 const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
 {
 	/*
 	 * this program might be calling bpf_trace_printk,
 	 * so allocate per-cpu printk buffers
 	 */
 	trace_printk_init_buffers();

 	return &bpf_trace_printk_proto;
 }

 static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
 {
 	struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
 	struct bpf_array *array = container_of(map, struct bpf_array, map);
 	struct perf_event *event;

 	if (unlikely(index >= array->map.max_entries))
 		return -E2BIG;

 	event = (struct perf_event *)array->ptrs[index];
 	if (!event)
 		return -ENOENT;

 	/* make sure event is local and doesn't have pmu::count */
 	if (event->oncpu != smp_processor_id() ||
 	    event->pmu->count)
 		return -EINVAL;

 	/*
 	 * we don't know if the function is run successfully by the
 	 * return value. It can be judged in other places, such as
 	 * eBPF programs.
 	 */
 	return perf_event_read_local(event);
 }

 static const struct bpf_func_proto bpf_perf_event_read_proto = {
 	.func		= bpf_perf_event_read,
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_CONST_MAP_PTR,
 	.arg2_type	= ARG_ANYTHING,
 };

 static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 index, u64 r4, u64 size)
 {
 	struct pt_regs *regs = (struct pt_regs *) (long) r1;
 	struct bpf_map *map = (struct bpf_map *) (long) r2;
 	struct bpf_array *array = container_of(map, struct bpf_array, map);
 	void *data = (void *) (long) r4;
 	struct perf_sample_data sample_data;
 	struct perf_event *event;
 	struct perf_raw_record raw = {
 		.size = size,
 		.data = data,
 	};

 	if (unlikely(index >= array->map.max_entries))
 		return -E2BIG;

 	event = (struct perf_event *)array->ptrs[index];
 	if (unlikely(!event))
 		return -ENOENT;

 	if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
 		     event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
 		return -EINVAL;

 	if (unlikely(event->oncpu != smp_processor_id()))
 		return -EOPNOTSUPP;

 	perf_sample_data_init(&sample_data, 0, 0);
 	sample_data.raw = &raw;
 	perf_event_output(event, &sample_data, regs);
 	return 0;
 }

 static const struct bpf_func_proto bpf_perf_event_output_proto = {
 	.func		= bpf_perf_event_output,
 	.gpl_only	= true,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
 	.arg4_type	= ARG_PTR_TO_STACK,
 	.arg5_type	= ARG_CONST_STACK_SIZE,
 };

 static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
 {
 	switch (func_id) {
 	case BPF_FUNC_map_lookup_elem:
 		return &bpf_map_lookup_elem_proto;
 	case BPF_FUNC_map_update_elem:
 		return &bpf_map_update_elem_proto;
 	case BPF_FUNC_map_delete_elem:
 		return &bpf_map_delete_elem_proto;
 	case BPF_FUNC_probe_read:
 		return &bpf_probe_read_proto;
 	case BPF_FUNC_ktime_get_ns:
 		return &bpf_ktime_get_ns_proto;
 	case BPF_FUNC_tail_call:
 		return &bpf_tail_call_proto;
 	case BPF_FUNC_get_current_pid_tgid:
 		return &bpf_get_current_pid_tgid_proto;
 	case BPF_FUNC_get_current_uid_gid:
 		return &bpf_get_current_uid_gid_proto;
 	case BPF_FUNC_get_current_comm:
 		return &bpf_get_current_comm_proto;
 	case BPF_FUNC_trace_printk:
 		return bpf_get_trace_printk_proto();
 	case BPF_FUNC_get_smp_processor_id:
 		return &bpf_get_smp_processor_id_proto;
 	case BPF_FUNC_perf_event_read:
 		return &bpf_perf_event_read_proto;
 	case BPF_FUNC_perf_event_output:
 		return &bpf_perf_event_output_proto;
 	default:
 		return NULL;
 	}
 }

 /* bpf+kprobe programs can access fields of 'struct pt_regs' */
 static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type)
 {
 	/* check bounds */
 	if (off < 0 || off >= sizeof(struct pt_regs))
 		return false;

 	/* only read is allowed */
 	if (type != BPF_READ)
 		return false;

 	/* disallow misaligned access */
 	if (off % size != 0)
 		return false;

 	return true;
 }

 static const struct bpf_verifier_ops kprobe_prog_ops = {
 	.get_func_proto  = kprobe_prog_func_proto,
 	.is_valid_access = kprobe_prog_is_valid_access,
 };

 static struct bpf_prog_type_list kprobe_tl = {
 	.ops	= &kprobe_prog_ops,
 	.type	= BPF_PROG_TYPE_KPROBE,
 };

 static int __init register_kprobe_prog_ops(void)
 {
 	bpf_register_prog_type(&kprobe_tl);
 	return 0;
 }
 late_initcall(register_kprobe_prog_ops);
	/* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of version 2 of the GNU General Public
	* License as published by the Free Software Foundation.
	*/
	#include <linux/kernel.h>
	#include <linux/types.h>
	#include <linux/slab.h>
	#include <linux/bpf.h>
	#include <linux/filter.h>
	#include <linux/uaccess.h>
	#include <linux/ctype.h>
	#include "trace.h"

	static DEFINE_PER_CPU(int, bpf_prog_active);

	/**
	* trace_call_bpf - invoke BPF program
	* @prog: BPF program
	* @ctx: opaque context pointer
	*
	* kprobe handlers execute BPF programs via this helper.
	* Can be used from static tracepoints in the future.
	*
	* Return: BPF programs always return an integer which is interpreted by
	* kprobe handler as:
	* 0 - return from kprobe (event is filtered out)
	* 1 - store kprobe event into ring buffer
	* Other values are reserved and currently alias to 1
	*/
	unsigned int trace_call_bpf(struct bpf_prog prog, void ctx)
	{
	unsigned int ret;

	if (in_nmi()) /* not supported yet */
	return 1;

	preempt_disable();

	if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
	/*
	* since some bpf program is already running on this cpu,
	* don't call into another bpf program (same or different)
	* and don't send kprobe event into ring-buffer,
	* so return zero here
	*/
	ret = 0;
	goto out;
	}

	rcu_read_lock();
	ret = BPF_PROG_RUN(prog, ctx);
	rcu_read_unlock();

	out:
	__this_cpu_dec(bpf_prog_active);
	preempt_enable();

	return ret;
	}
	EXPORT_SYMBOL_GPL(trace_call_bpf);

	static u64 bpf_probe_read(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
	{
	void dst = (void ) (long) r1;
	int size = (int) r2;
	void unsafe_ptr = (void ) (long) r3;

	return probe_kernel_read(dst, unsafe_ptr, size);
	}

	static const struct bpf_func_proto bpf_probe_read_proto = {
	.func = bpf_probe_read,
	.gpl_only = true,
	.ret_type = RET_INTEGER,
	.arg1_type = ARG_PTR_TO_STACK,
	.arg2_type = ARG_CONST_STACK_SIZE,
	.arg3_type = ARG_ANYTHING,
	};

	/*
	* limited trace_printk()
	* only %d %u %x %ld %lu %lx %lld %llu %llx %p %s conversion specifiers allowed
	*/
	static u64 bpf_trace_printk(u64 r1, u64 fmt_size, u64 r3, u64 r4, u64 r5)
	{
	char fmt = (char ) (long) r1;
	bool str_seen = false;
	int mod[3] = {};
	int fmt_cnt = 0;
	u64 unsafe_addr;
	char buf[64];
	int i;

	/*
	* bpf_check()->check_func_arg()->check_stack_boundary()
	* guarantees that fmt points to bpf program stack,
	* fmt_size bytes of it were initialized and fmt_size > 0
	*/
	if (fmt[--fmt_size] != 0)
	return -EINVAL;

	/* check format string for allowed specifiers */
	for (i = 0; i < fmt_size; i++) {
	if ((!isprint(fmt[i]) && !isspace(fmt[i])) \|\| !isascii(fmt[i]))
	return -EINVAL;

	if (fmt[i] != '%')
	continue;

	if (fmt_cnt >= 3)
	return -EINVAL;

	/* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */
	i++;
	if (fmt[i] == 'l') {
	mod[fmt_cnt]++;
	i++;
	} else if (fmt[i] == 'p' \|\| fmt[i] == 's') {
	mod[fmt_cnt]++;
	i++;
	if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0)
	return -EINVAL;
	fmt_cnt++;
	if (fmt[i - 1] == 's') {
	if (str_seen)
	/* allow only one '%s' per fmt string */
	return -EINVAL;
	str_seen = true;

	switch (fmt_cnt) {
	case 1:
	unsafe_addr = r3;
	r3 = (long) buf;
	break;
	case 2:
	unsafe_addr = r4;
	r4 = (long) buf;
	break;
	case 3:
	unsafe_addr = r5;
	r5 = (long) buf;
	break;
	}
	buf[0] = 0;
	strncpy_from_unsafe(buf,
	(void *) (long) unsafe_addr,
	sizeof(buf));
	}
	continue;
	}

	if (fmt[i] == 'l') {
	mod[fmt_cnt]++;
	i++;
	}

	if (fmt[i] != 'd' && fmt[i] != 'u' && fmt[i] != 'x')
	return -EINVAL;
	fmt_cnt++;
	}

	return __trace_printk(1/* fake ip will not be printed */, fmt,
	mod[0] == 2 ? r3 : mod[0] == 1 ? (long) r3 : (u32) r3,
	mod[1] == 2 ? r4 : mod[1] == 1 ? (long) r4 : (u32) r4,
	mod[2] == 2 ? r5 : mod[2] == 1 ? (long) r5 : (u32) r5);
	}

	static const struct bpf_func_proto bpf_trace_printk_proto = {
	.func = bpf_trace_printk,
	.gpl_only = true,
	.ret_type = RET_INTEGER,
	.arg1_type = ARG_PTR_TO_STACK,
	.arg2_type = ARG_CONST_STACK_SIZE,
	};

	const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
	{
	/*
	* this program might be calling bpf_trace_printk,
	* so allocate per-cpu printk buffers
	*/
	trace_printk_init_buffers();

	return &bpf_trace_printk_proto;
	}

	static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5)
	{
	struct bpf_map map = (struct bpf_map ) (unsigned long) r1;
	struct bpf_array *array = container_of(map, struct bpf_array, map);
	struct perf_event *event;

	if (unlikely(index >= array->map.max_entries))
	return -E2BIG;

	event = (struct perf_event *)array->ptrs[index];
	if (!event)
	return -ENOENT;

	/* make sure event is local and doesn't have pmu::count */
	if (event->oncpu != smp_processor_id() \|\|
	event->pmu->count)
	return -EINVAL;

	/*
	* we don't know if the function is run successfully by the
	* return value. It can be judged in other places, such as
	* eBPF programs.
	*/
	return perf_event_read_local(event);
	}

	static const struct bpf_func_proto bpf_perf_event_read_proto = {
	.func = bpf_perf_event_read,
	.gpl_only = true,
	.ret_type = RET_INTEGER,
	.arg1_type = ARG_CONST_MAP_PTR,
	.arg2_type = ARG_ANYTHING,
	};

	static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 index, u64 r4, u64 size)
	{
	struct pt_regs regs = (struct pt_regs ) (long) r1;
	struct bpf_map map = (struct bpf_map ) (long) r2;
	struct bpf_array *array = container_of(map, struct bpf_array, map);
	void data = (void ) (long) r4;
	struct perf_sample_data sample_data;
	struct perf_event *event;
	struct perf_raw_record raw = {
	.size = size,
	.data = data,
	};

	if (unlikely(index >= array->map.max_entries))
	return -E2BIG;

	event = (struct perf_event *)array->ptrs[index];
	if (unlikely(!event))
	return -ENOENT;

	if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE \|\|
	event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
	return -EINVAL;

	if (unlikely(event->oncpu != smp_processor_id()))
	return -EOPNOTSUPP;

	perf_sample_data_init(&sample_data, 0, 0);
	sample_data.raw = &raw;
	perf_event_output(event, &sample_data, regs);
	return 0;
	}

	static const struct bpf_func_proto bpf_perf_event_output_proto = {
	.func = bpf_perf_event_output,
	.gpl_only = true,
	.ret_type = RET_INTEGER,
	.arg1_type = ARG_PTR_TO_CTX,
	.arg2_type = ARG_CONST_MAP_PTR,
	.arg3_type = ARG_ANYTHING,
	.arg4_type = ARG_PTR_TO_STACK,
	.arg5_type = ARG_CONST_STACK_SIZE,
	};

	static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
	{
	switch (func_id) {
	case BPF_FUNC_map_lookup_elem:
	return &bpf_map_lookup_elem_proto;
	case BPF_FUNC_map_update_elem:
	return &bpf_map_update_elem_proto;
	case BPF_FUNC_map_delete_elem:
	return &bpf_map_delete_elem_proto;
	case BPF_FUNC_probe_read:
	return &bpf_probe_read_proto;
	case BPF_FUNC_ktime_get_ns:
	return &bpf_ktime_get_ns_proto;
	case BPF_FUNC_tail_call:
	return &bpf_tail_call_proto;
	case BPF_FUNC_get_current_pid_tgid:
	return &bpf_get_current_pid_tgid_proto;
	case BPF_FUNC_get_current_uid_gid:
	return &bpf_get_current_uid_gid_proto;
	case BPF_FUNC_get_current_comm:
	return &bpf_get_current_comm_proto;
	case BPF_FUNC_trace_printk:
	return bpf_get_trace_printk_proto();
	case BPF_FUNC_get_smp_processor_id:
	return &bpf_get_smp_processor_id_proto;
	case BPF_FUNC_perf_event_read:
	return &bpf_perf_event_read_proto;
	case BPF_FUNC_perf_event_output:
	return &bpf_perf_event_output_proto;
	default:
	return NULL;
	}
	}

	/* bpf+kprobe programs can access fields of 'struct pt_regs' */
	static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type)
	{
	/* check bounds */
	if (off < 0 \|\| off >= sizeof(struct pt_regs))
	return false;

	/* only read is allowed */
	if (type != BPF_READ)
	return false;

	/* disallow misaligned access */
	if (off % size != 0)
	return false;

	return true;
	}

	static const struct bpf_verifier_ops kprobe_prog_ops = {
	.get_func_proto = kprobe_prog_func_proto,
	.is_valid_access = kprobe_prog_is_valid_access,
	};

	static struct bpf_prog_type_list kprobe_tl = {
	.ops = &kprobe_prog_ops,
	.type = BPF_PROG_TYPE_KPROBE,
	};

	static int __init register_kprobe_prog_ops(void)
	{
	bpf_register_prog_type(&kprobe_tl);
	return 0;
	}
	late_initcall(register_kprobe_prog_ops);