/* 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,}; static u64 bpf_ktime_get_ns(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5){	/* NMI safe access to clock monotonic */	return ktime_get_mono_fast_ns();} static const struct bpf_func_proto bpf_ktime_get_ns_proto = {	.func		= bpf_ktime_get_ns,	.gpl_only	= true,	.ret_type	= RET_INTEGER,}; /* * limited trace_printk() * only %d %u %x %ld %lu %lx %lld %llu %llx %p conversion specifiers allowed */static u64 bpf_trace_printk(u64 r1, u64 fmt_size, u64 r3, u64 r4, u64 r5){	char *fmt = (char *) (long) r1;	int mod[3] = {};	int fmt_cnt = 0;	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') {			mod[fmt_cnt]++;			i++;			if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0)				return -EINVAL;			fmt_cnt++;			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,}; 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_trace_printk:		/*		 * this program might be calling bpf_trace_printk,		 * so allocate per-cpu printk buffers		 */		trace_printk_init_buffers(); 		return &bpf_trace_printk_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 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);