/
npf_ext_rndblock.c
189 lines (165 loc) · 4.89 KB
/
npf_ext_rndblock.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
/*-
* Copyright (c) 2012 The NetBSD Foundation, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* NPF random blocking extension - kernel module.
* This is also a demo extension.
*/
#ifdef _KERNEL
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: npf_ext_rndblock.c,v 1.9 2020/05/30 14:16:56 rmind Exp $");
#include <sys/types.h>
#include <sys/cprng.h>
#include <sys/atomic.h>
#include <sys/module.h>
#include <sys/kmem.h>
#endif
#include "npf_impl.h"
/*
* NPF extension module definition and the identifier.
*/
NPF_EXT_MODULE(npf_ext_rndblock, "");
#define NPFEXT_RNDBLOCK_VER 1
static void * npf_ext_rndblock_id;
#define PERCENTAGE_BASE 10000
/*
* Meta-data structure, containing parameters.
*/
typedef struct {
unsigned int mod;
unsigned long counter;
unsigned int percentage;
} npf_ext_rndblock_t;
/*
* npf_ext_rndblock_ctor: a constructor to parse and store any parameters
* associated with a rule procedure, which is being newly created.
*/
static int
npf_ext_rndblock_ctor(npf_rproc_t *rp, const nvlist_t *params)
{
npf_ext_rndblock_t *meta;
/*
* Allocate and a associate a structure for the parameter
* and our meta-data.
*/
meta = kmem_zalloc(sizeof(npf_ext_rndblock_t), KM_SLEEP);
meta->mod = dnvlist_get_number(params, "mod", 0);
meta->percentage = dnvlist_get_number(params, "percentage", 0);
npf_rproc_assign(rp, meta);
return 0;
}
/*
* npf_ext_rndblock_dtor: a destructor for our rule procedure.
*/
static void
npf_ext_rndblock_dtor(npf_rproc_t *rp, void *meta)
{
/* Free our meta-data, associated with the procedure. */
kmem_free(meta, sizeof(npf_ext_rndblock_t));
}
/*
* npf_ext_rndblock: main routine implementing the extension functionality.
*/
static bool
npf_ext_rndblock(npf_cache_t *npc, void *meta, const npf_match_info_t *mi,
int *decision)
{
npf_ext_rndblock_t *rndblock = meta;
unsigned long c;
/* Skip, if already blocking. */
if (*decision == NPF_DECISION_BLOCK) {
return true;
}
/*
* Sample demo:
*
* Drop the packets according to the given module or percentage.
*
* Rule procedures may be executed concurrently in an SMP system.
* Use atomic operation to increment the counter.
*/
c = atomic_inc_ulong_nv(&rndblock->counter);
if (rndblock->mod) {
if ((c % rndblock->mod) == 0) {
*decision = NPF_DECISION_BLOCK;
}
}
if (rndblock->percentage) {
uint32_t w = cprng_fast32() % PERCENTAGE_BASE;
if (w <= rndblock->percentage) {
*decision = NPF_DECISION_BLOCK;
}
}
return true;
}
__dso_public int
npf_ext_rndblock_init(npf_t *npf)
{
static const npf_ext_ops_t npf_rndblock_ops = {
.version = NPFEXT_RNDBLOCK_VER,
.ctx = NULL,
.ctor = npf_ext_rndblock_ctor,
.dtor = npf_ext_rndblock_dtor,
.proc = npf_ext_rndblock
};
/*
* Initialize the NPF extension. Register the "rndblock" extension
* calls (constructor, destructor, the processing routine, etc).
*/
npf_ext_rndblock_id = npf_ext_register(npf, "rndblock",
&npf_rndblock_ops);
return npf_ext_rndblock_id ? 0 : EEXIST;
}
__dso_public int
npf_ext_rndblock_fini(npf_t *npf)
{
/*
* Remove the rndblock extension. NPF may return an if there
* are active references and it cannot drain them.
*/
return npf_ext_unregister(npf, npf_ext_rndblock_id);
}
#ifdef _KERNEL
/*
* Kernel module interface.
*/
static int
npf_ext_rndblock_modcmd(modcmd_t cmd, void *arg)
{
npf_t *npf = npf_getkernctx();
switch (cmd) {
case MODULE_CMD_INIT:
return npf_ext_rndblock_init(npf);
case MODULE_CMD_FINI:
return npf_ext_rndblock_fini(npf);
case MODULE_CMD_AUTOUNLOAD:
/* Allow auto-unload only if NPF permits it. */
return npf_autounload_p() ? 0 : EBUSY;
default:
return ENOTTY;
}
return 0;
}
#endif