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 "vmlinux.h"
8 #include <linux/version.h>
9 #include <bpf/bpf_helpers.h>
10 #include <bpf/bpf_tracing.h>
11 #include <bpf/bpf_core_read.h>
12
13 struct {
14 __uint(type, BPF_MAP_TYPE_HASH);
15 __type(key, long);
16 __type(value, long);
17 __uint(max_entries, 1024);
18 } my_map SEC(".maps");
19
20 /* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
21 * example will no longer be meaningful
22 */
23 SEC("kprobe/kfree_skb_reason")
24 int bpf_prog2(struct pt_regs *ctx)
25 {
26 long loc = 0;
27 long init_val = 1;
28 long *value;
29
30 /* read ip of kfree_skb_reason caller.
31 * non-portable version of __builtin_return_address(0)
32 */
33 BPF_KPROBE_READ_RET_IP(loc, ctx);
34
35 value = bpf_map_lookup_elem(&my_map, &loc);
36 if (value)
37 *value += 1;
38 else
39 bpf_map_update_elem(&my_map, &loc, &init_val, BPF_ANY);
40 return 0;
41 }
42
43 static unsigned int log2(unsigned int v)
44 {
45 unsigned int r;
46 unsigned int shift;
47
48 r = (v > 0xFFFF) << 4; v >>= r;
49 shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
50 shift = (v > 0xF) << 2; v >>= shift; r |= shift;
51 shift = (v > 0x3) << 1; v >>= shift; r |= shift;
52 r |= (v >> 1);
53 return r;
54 }
55
56 static unsigned int log2l(unsigned long v)
57 {
58 unsigned int hi = v >> 32;
59 if (hi)
60 return log2(hi) + 32;
61 else
62 return log2(v);
63 }
64
65 struct hist_key {
66 char comm[16];
67 u64 pid_tgid;
68 u64 uid_gid;
69 u64 index;
70 };
71
72 struct {
73 __uint(type, BPF_MAP_TYPE_PERCPU_HASH);
74 __uint(key_size, sizeof(struct hist_key));
75 __uint(value_size, sizeof(long));
76 __uint(max_entries, 1024);
77 } my_hist_map SEC(".maps");
78
79 SEC("ksyscall/write")
80 int BPF_KSYSCALL(bpf_prog3, unsigned int fd, const char *buf, size_t count)
81 {
82 long init_val = 1;
83 long *value;
84 struct hist_key key;
85
86 key.index = log2l(count);
87 key.pid_tgid = bpf_get_current_pid_tgid();
88 key.uid_gid = bpf_get_current_uid_gid();
89 bpf_get_current_comm(&key.comm, sizeof(key.comm));
90
91 value = bpf_map_lookup_elem(&my_hist_map, &key);
92 if (value)
93 __sync_fetch_and_add(value, 1);
94 else
95 bpf_map_update_elem(&my_hist_map, &key, &init_val, BPF_ANY);
96 return 0;
97 }
98 char _license[] SEC("license") = "GPL";
99 u32 _version SEC("version") = LINUX_VERSION_CODE;
100
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.