1 /* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 */
7 #include <linux/skbuff.h>
8 #include <linux/netdevice.h>
9 #include <linux/version.h>
10 #include <uapi/linux/bpf.h>
11 #include <bpf/bpf_helpers.h>
12 #include <bpf/bpf_tracing.h>
13 #include "trace_common.h"
14
15 struct {
16 __uint(type, BPF_MAP_TYPE_HASH);
17 __type(key, long);
18 __type(value, long);
19 __uint(max_entries, 1024);
20 } my_map SEC(".maps");
21
22 /* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
23 * example will no longer be meaningful
24 */
25 SEC("kprobe/kfree_skb")
bpf_prog2(struct pt_regs * ctx)26 int bpf_prog2(struct pt_regs *ctx)
27 {
28 long loc = 0;
29 long init_val = 1;
30 long *value;
31
32 /* read ip of kfree_skb caller.
33 * non-portable version of __builtin_return_address(0)
34 */
35 BPF_KPROBE_READ_RET_IP(loc, ctx);
36
37 value = bpf_map_lookup_elem(&my_map, &loc);
38 if (value)
39 *value += 1;
40 else
41 bpf_map_update_elem(&my_map, &loc, &init_val, BPF_ANY);
42 return 0;
43 }
44
log2(unsigned int v)45 static unsigned int log2(unsigned int v)
46 {
47 unsigned int r;
48 unsigned int shift;
49
50 r = (v > 0xFFFF) << 4; v >>= r;
51 shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
52 shift = (v > 0xF) << 2; v >>= shift; r |= shift;
53 shift = (v > 0x3) << 1; v >>= shift; r |= shift;
54 r |= (v >> 1);
55 return r;
56 }
57
log2l(unsigned long v)58 static unsigned int log2l(unsigned long v)
59 {
60 unsigned int hi = v >> 32;
61 if (hi)
62 return log2(hi) + 32;
63 else
64 return log2(v);
65 }
66
67 struct hist_key {
68 char comm[16];
69 u64 pid_tgid;
70 u64 uid_gid;
71 u64 index;
72 };
73
74 struct {
75 __uint(type, BPF_MAP_TYPE_PERCPU_HASH);
76 __uint(key_size, sizeof(struct hist_key));
77 __uint(value_size, sizeof(long));
78 __uint(max_entries, 1024);
79 } my_hist_map SEC(".maps");
80
SYSCALL(sys_write)81 SEC("kprobe/" SYSCALL(sys_write))
82 int bpf_prog3(struct pt_regs *ctx)
83 {
84 long write_size = PT_REGS_PARM3(ctx);
85 long init_val = 1;
86 long *value;
87 struct hist_key key;
88
89 key.index = log2l(write_size);
90 key.pid_tgid = bpf_get_current_pid_tgid();
91 key.uid_gid = bpf_get_current_uid_gid();
92 bpf_get_current_comm(&key.comm, sizeof(key.comm));
93
94 value = bpf_map_lookup_elem(&my_hist_map, &key);
95 if (value)
96 __sync_fetch_and_add(value, 1);
97 else
98 bpf_map_update_elem(&my_hist_map, &key, &init_val, BPF_ANY);
99 return 0;
100 }
101 char _license[] SEC("license") = "GPL";
102 u32 _version SEC("version") = LINUX_VERSION_CODE;
103