562 lines
14 KiB
C
562 lines
14 KiB
C
/* Copyright (c) 2011-2015 PLUMgrid, http://plumgrid.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/bpf.h>
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#include <linux/filter.h>
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#include <linux/uaccess.h>
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#include <linux/ctype.h>
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#include "trace.h"
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/**
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* trace_call_bpf - invoke BPF program
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* @prog: BPF program
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* @ctx: opaque context pointer
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*
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* kprobe handlers execute BPF programs via this helper.
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* Can be used from static tracepoints in the future.
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*
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* Return: BPF programs always return an integer which is interpreted by
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* kprobe handler as:
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* 0 - return from kprobe (event is filtered out)
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* 1 - store kprobe event into ring buffer
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* Other values are reserved and currently alias to 1
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*/
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unsigned int trace_call_bpf(struct bpf_prog *prog, void *ctx)
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{
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unsigned int ret;
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if (in_nmi()) /* not supported yet */
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return 1;
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preempt_disable();
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if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
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/*
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* since some bpf program is already running on this cpu,
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* don't call into another bpf program (same or different)
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* and don't send kprobe event into ring-buffer,
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* so return zero here
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*/
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ret = 0;
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goto out;
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}
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rcu_read_lock();
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ret = BPF_PROG_RUN(prog, ctx);
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rcu_read_unlock();
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out:
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__this_cpu_dec(bpf_prog_active);
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preempt_enable();
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return ret;
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}
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EXPORT_SYMBOL_GPL(trace_call_bpf);
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static u64 bpf_probe_read(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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{
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void *dst = (void *) (long) r1;
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int ret, size = (int) r2;
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void *unsafe_ptr = (void *) (long) r3;
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ret = probe_kernel_read(dst, unsafe_ptr, size);
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if (unlikely(ret < 0))
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memset(dst, 0, size);
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return ret;
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}
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static const struct bpf_func_proto bpf_probe_read_proto = {
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.func = bpf_probe_read,
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.gpl_only = true,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_RAW_STACK,
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.arg2_type = ARG_CONST_STACK_SIZE,
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.arg3_type = ARG_ANYTHING,
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};
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static u64 bpf_probe_write_user(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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{
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void *unsafe_ptr = (void *) (long) r1;
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void *src = (void *) (long) r2;
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int size = (int) r3;
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/*
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* Ensure we're in user context which is safe for the helper to
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* run. This helper has no business in a kthread.
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*
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* access_ok() should prevent writing to non-user memory, but in
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* some situations (nommu, temporary switch, etc) access_ok() does
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* not provide enough validation, hence the check on KERNEL_DS.
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*/
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if (unlikely(in_interrupt() ||
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current->flags & (PF_KTHREAD | PF_EXITING)))
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return -EPERM;
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if (unlikely(segment_eq(get_fs(), KERNEL_DS)))
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return -EPERM;
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if (!access_ok(VERIFY_WRITE, unsafe_ptr, size))
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return -EPERM;
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return probe_kernel_write(unsafe_ptr, src, size);
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}
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static const struct bpf_func_proto bpf_probe_write_user_proto = {
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.func = bpf_probe_write_user,
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.gpl_only = true,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_ANYTHING,
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.arg2_type = ARG_PTR_TO_STACK,
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.arg3_type = ARG_CONST_STACK_SIZE,
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};
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static const struct bpf_func_proto *bpf_get_probe_write_proto(void)
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{
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pr_warn_ratelimited("%s[%d] is installing a program with bpf_probe_write_user helper that may corrupt user memory!",
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current->comm, task_pid_nr(current));
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return &bpf_probe_write_user_proto;
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}
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/*
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* limited trace_printk()
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* only %d %u %x %ld %lu %lx %lld %llu %llx %p %s conversion specifiers allowed
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*/
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static u64 bpf_trace_printk(u64 r1, u64 fmt_size, u64 r3, u64 r4, u64 r5)
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{
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char *fmt = (char *) (long) r1;
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bool str_seen = false;
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int mod[3] = {};
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int fmt_cnt = 0;
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u64 unsafe_addr;
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char buf[64];
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int i;
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/*
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* bpf_check()->check_func_arg()->check_stack_boundary()
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* guarantees that fmt points to bpf program stack,
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* fmt_size bytes of it were initialized and fmt_size > 0
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*/
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if (fmt[--fmt_size] != 0)
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return -EINVAL;
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/* check format string for allowed specifiers */
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for (i = 0; i < fmt_size; i++) {
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if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i]))
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return -EINVAL;
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if (fmt[i] != '%')
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continue;
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if (fmt_cnt >= 3)
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return -EINVAL;
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/* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */
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i++;
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if (fmt[i] == 'l') {
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mod[fmt_cnt]++;
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i++;
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} else if (fmt[i] == 'p' || fmt[i] == 's') {
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mod[fmt_cnt]++;
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i++;
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if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0)
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return -EINVAL;
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fmt_cnt++;
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if (fmt[i - 1] == 's') {
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if (str_seen)
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/* allow only one '%s' per fmt string */
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return -EINVAL;
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str_seen = true;
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switch (fmt_cnt) {
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case 1:
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unsafe_addr = r3;
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r3 = (long) buf;
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break;
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case 2:
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unsafe_addr = r4;
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r4 = (long) buf;
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break;
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case 3:
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unsafe_addr = r5;
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r5 = (long) buf;
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break;
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}
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buf[0] = 0;
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strncpy_from_unsafe(buf,
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(void *) (long) unsafe_addr,
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sizeof(buf));
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}
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continue;
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}
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if (fmt[i] == 'l') {
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mod[fmt_cnt]++;
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i++;
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}
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if (fmt[i] != 'd' && fmt[i] != 'u' && fmt[i] != 'x')
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return -EINVAL;
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fmt_cnt++;
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}
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return __trace_printk(1/* fake ip will not be printed */, fmt,
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mod[0] == 2 ? r3 : mod[0] == 1 ? (long) r3 : (u32) r3,
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mod[1] == 2 ? r4 : mod[1] == 1 ? (long) r4 : (u32) r4,
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mod[2] == 2 ? r5 : mod[2] == 1 ? (long) r5 : (u32) r5);
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}
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static const struct bpf_func_proto bpf_trace_printk_proto = {
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.func = bpf_trace_printk,
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.gpl_only = true,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_STACK,
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.arg2_type = ARG_CONST_STACK_SIZE,
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};
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const struct bpf_func_proto *bpf_get_trace_printk_proto(void)
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{
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/*
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* this program might be calling bpf_trace_printk,
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* so allocate per-cpu printk buffers
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*/
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trace_printk_init_buffers();
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return &bpf_trace_printk_proto;
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}
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static u64 bpf_perf_event_read(u64 r1, u64 flags, u64 r3, u64 r4, u64 r5)
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{
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struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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unsigned int cpu = smp_processor_id();
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u64 index = flags & BPF_F_INDEX_MASK;
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struct bpf_event_entry *ee;
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struct perf_event *event;
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if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
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return -EINVAL;
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if (index == BPF_F_CURRENT_CPU)
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index = cpu;
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if (unlikely(index >= array->map.max_entries))
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return -E2BIG;
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ee = READ_ONCE(array->ptrs[index]);
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if (!ee)
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return -ENOENT;
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event = ee->event;
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if (unlikely(event->attr.type != PERF_TYPE_HARDWARE &&
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event->attr.type != PERF_TYPE_RAW))
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return -EINVAL;
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/* make sure event is local and doesn't have pmu::count */
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if (unlikely(event->oncpu != cpu || event->pmu->count))
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return -EINVAL;
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/*
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* we don't know if the function is run successfully by the
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* return value. It can be judged in other places, such as
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* eBPF programs.
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*/
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return perf_event_read_local(event);
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}
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static const struct bpf_func_proto bpf_perf_event_read_proto = {
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.func = bpf_perf_event_read,
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.gpl_only = true,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_CONST_MAP_PTR,
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.arg2_type = ARG_ANYTHING,
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};
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static __always_inline u64
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__bpf_perf_event_output(struct pt_regs *regs, struct bpf_map *map,
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u64 flags, struct perf_raw_record *raw)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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unsigned int cpu = smp_processor_id();
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u64 index = flags & BPF_F_INDEX_MASK;
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struct perf_sample_data sample_data;
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struct bpf_event_entry *ee;
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struct perf_event *event;
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if (index == BPF_F_CURRENT_CPU)
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index = cpu;
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if (unlikely(index >= array->map.max_entries))
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return -E2BIG;
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ee = READ_ONCE(array->ptrs[index]);
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if (!ee)
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return -ENOENT;
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event = ee->event;
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if (unlikely(event->attr.type != PERF_TYPE_SOFTWARE ||
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event->attr.config != PERF_COUNT_SW_BPF_OUTPUT))
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return -EINVAL;
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if (unlikely(event->oncpu != cpu))
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return -EOPNOTSUPP;
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perf_sample_data_init(&sample_data, 0, 0);
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sample_data.raw = raw;
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perf_event_output(event, &sample_data, regs);
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return 0;
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}
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static u64 bpf_perf_event_output(u64 r1, u64 r2, u64 flags, u64 r4, u64 size)
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{
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struct pt_regs *regs = (struct pt_regs *)(long) r1;
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struct bpf_map *map = (struct bpf_map *)(long) r2;
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void *data = (void *)(long) r4;
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struct perf_raw_record raw = {
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.frag = {
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.size = size,
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.data = data,
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},
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};
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if (unlikely(flags & ~(BPF_F_INDEX_MASK)))
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return -EINVAL;
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return __bpf_perf_event_output(regs, map, flags, &raw);
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}
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static const struct bpf_func_proto bpf_perf_event_output_proto = {
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.func = bpf_perf_event_output,
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.gpl_only = true,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_PTR_TO_CTX,
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.arg2_type = ARG_CONST_MAP_PTR,
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.arg3_type = ARG_ANYTHING,
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.arg4_type = ARG_PTR_TO_STACK,
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.arg5_type = ARG_CONST_STACK_SIZE,
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};
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static DEFINE_PER_CPU(struct pt_regs, bpf_pt_regs);
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u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
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void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy)
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{
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struct pt_regs *regs = this_cpu_ptr(&bpf_pt_regs);
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struct perf_raw_frag frag = {
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.copy = ctx_copy,
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.size = ctx_size,
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.data = ctx,
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};
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struct perf_raw_record raw = {
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.frag = {
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{
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.next = ctx_size ? &frag : NULL,
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},
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.size = meta_size,
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.data = meta,
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},
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};
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perf_fetch_caller_regs(regs);
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return __bpf_perf_event_output(regs, map, flags, &raw);
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}
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static u64 bpf_get_current_task(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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{
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return (long) current;
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}
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static const struct bpf_func_proto bpf_get_current_task_proto = {
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.func = bpf_get_current_task,
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.gpl_only = true,
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.ret_type = RET_INTEGER,
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};
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static u64 bpf_current_task_under_cgroup(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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{
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struct bpf_map *map = (struct bpf_map *)(long)r1;
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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struct cgroup *cgrp;
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u32 idx = (u32)r2;
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if (unlikely(in_interrupt()))
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return -EINVAL;
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if (unlikely(idx >= array->map.max_entries))
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return -E2BIG;
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cgrp = READ_ONCE(array->ptrs[idx]);
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if (unlikely(!cgrp))
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return -EAGAIN;
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return task_under_cgroup_hierarchy(current, cgrp);
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}
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static const struct bpf_func_proto bpf_current_task_under_cgroup_proto = {
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.func = bpf_current_task_under_cgroup,
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.gpl_only = false,
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.ret_type = RET_INTEGER,
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.arg1_type = ARG_CONST_MAP_PTR,
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.arg2_type = ARG_ANYTHING,
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};
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static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id)
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{
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switch (func_id) {
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case BPF_FUNC_map_lookup_elem:
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return &bpf_map_lookup_elem_proto;
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case BPF_FUNC_map_update_elem:
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return &bpf_map_update_elem_proto;
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case BPF_FUNC_map_delete_elem:
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return &bpf_map_delete_elem_proto;
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case BPF_FUNC_probe_read:
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return &bpf_probe_read_proto;
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case BPF_FUNC_ktime_get_ns:
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return &bpf_ktime_get_ns_proto;
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case BPF_FUNC_tail_call:
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return &bpf_tail_call_proto;
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case BPF_FUNC_get_current_pid_tgid:
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return &bpf_get_current_pid_tgid_proto;
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case BPF_FUNC_get_current_task:
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return &bpf_get_current_task_proto;
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case BPF_FUNC_get_current_uid_gid:
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return &bpf_get_current_uid_gid_proto;
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case BPF_FUNC_get_current_comm:
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return &bpf_get_current_comm_proto;
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case BPF_FUNC_trace_printk:
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return bpf_get_trace_printk_proto();
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case BPF_FUNC_get_smp_processor_id:
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return &bpf_get_smp_processor_id_proto;
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case BPF_FUNC_perf_event_read:
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return &bpf_perf_event_read_proto;
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case BPF_FUNC_probe_write_user:
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return bpf_get_probe_write_proto();
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case BPF_FUNC_current_task_under_cgroup:
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return &bpf_current_task_under_cgroup_proto;
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case BPF_FUNC_get_prandom_u32:
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return &bpf_get_prandom_u32_proto;
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default:
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return NULL;
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}
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}
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static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id)
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{
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switch (func_id) {
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case BPF_FUNC_perf_event_output:
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return &bpf_perf_event_output_proto;
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case BPF_FUNC_get_stackid:
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return &bpf_get_stackid_proto;
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default:
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return tracing_func_proto(func_id);
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}
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}
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/* bpf+kprobe programs can access fields of 'struct pt_regs' */
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static bool kprobe_prog_is_valid_access(int off, int size, enum bpf_access_type type,
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enum bpf_reg_type *reg_type)
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{
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if (off < 0 || off >= sizeof(struct pt_regs))
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return false;
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if (type != BPF_READ)
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return false;
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if (off % size != 0)
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return false;
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return true;
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}
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static const struct bpf_verifier_ops kprobe_prog_ops = {
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.get_func_proto = kprobe_prog_func_proto,
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.is_valid_access = kprobe_prog_is_valid_access,
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};
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static struct bpf_prog_type_list kprobe_tl = {
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.ops = &kprobe_prog_ops,
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.type = BPF_PROG_TYPE_KPROBE,
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};
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static u64 bpf_perf_event_output_tp(u64 r1, u64 r2, u64 index, u64 r4, u64 size)
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{
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/*
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* r1 points to perf tracepoint buffer where first 8 bytes are hidden
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* from bpf program and contain a pointer to 'struct pt_regs'. Fetch it
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* from there and call the same bpf_perf_event_output() helper
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*/
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u64 ctx = *(long *)(uintptr_t)r1;
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return bpf_perf_event_output(ctx, r2, index, r4, size);
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}
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static const struct bpf_func_proto bpf_perf_event_output_proto_tp = {
|
|
.func = bpf_perf_event_output_tp,
|
|
.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 u64 bpf_get_stackid_tp(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
|
|
{
|
|
u64 ctx = *(long *)(uintptr_t)r1;
|
|
|
|
return bpf_get_stackid(ctx, r2, r3, r4, r5);
|
|
}
|
|
|
|
static const struct bpf_func_proto bpf_get_stackid_proto_tp = {
|
|
.func = bpf_get_stackid_tp,
|
|
.gpl_only = true,
|
|
.ret_type = RET_INTEGER,
|
|
.arg1_type = ARG_PTR_TO_CTX,
|
|
.arg2_type = ARG_CONST_MAP_PTR,
|
|
.arg3_type = ARG_ANYTHING,
|
|
};
|
|
|
|
static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)
|
|
{
|
|
switch (func_id) {
|
|
case BPF_FUNC_perf_event_output:
|
|
return &bpf_perf_event_output_proto_tp;
|
|
case BPF_FUNC_get_stackid:
|
|
return &bpf_get_stackid_proto_tp;
|
|
default:
|
|
return tracing_func_proto(func_id);
|
|
}
|
|
}
|
|
|
|
static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type,
|
|
enum bpf_reg_type *reg_type)
|
|
{
|
|
if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE)
|
|
return false;
|
|
if (type != BPF_READ)
|
|
return false;
|
|
if (off % size != 0)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
static const struct bpf_verifier_ops tracepoint_prog_ops = {
|
|
.get_func_proto = tp_prog_func_proto,
|
|
.is_valid_access = tp_prog_is_valid_access,
|
|
};
|
|
|
|
static struct bpf_prog_type_list tracepoint_tl = {
|
|
.ops = &tracepoint_prog_ops,
|
|
.type = BPF_PROG_TYPE_TRACEPOINT,
|
|
};
|
|
|
|
static int __init register_kprobe_prog_ops(void)
|
|
{
|
|
bpf_register_prog_type(&kprobe_tl);
|
|
bpf_register_prog_type(&tracepoint_tl);
|
|
return 0;
|
|
}
|
|
late_initcall(register_kprobe_prog_ops);
|