1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * net/sched/em_text.c	Textsearch ematch
4 *
5 * Authors:	Thomas Graf <tgraf@suug.ch>
6 */
7
8#include <linux/slab.h>
9#include <linux/module.h>
10#include <linux/types.h>
11#include <linux/kernel.h>
12#include <linux/string.h>
13#include <linux/skbuff.h>
14#include <linux/textsearch.h>
15#include <linux/tc_ematch/tc_em_text.h>
16#include <net/pkt_cls.h>
17
18struct text_match {
19	u16			from_offset;
20	u16			to_offset;
21	u8			from_layer;
22	u8			to_layer;
23	struct ts_config	*config;
24};
25
26#define EM_TEXT_PRIV(m) ((struct text_match *) (m)->data)
27
28static int em_text_match(struct sk_buff *skb, struct tcf_ematch *m,
29			 struct tcf_pkt_info *info)
30{
31	struct text_match *tm = EM_TEXT_PRIV(m);
32	int from, to;
33
34	from = tcf_get_base_ptr(skb, tm->from_layer) - skb->data;
35	from += tm->from_offset;
36
37	to = tcf_get_base_ptr(skb, tm->to_layer) - skb->data;
38	to += tm->to_offset;
39
40	return skb_find_text(skb, from, to, tm->config) != UINT_MAX;
41}
42
43static int em_text_change(struct net *net, void *data, int len,
44			  struct tcf_ematch *m)
45{
46	struct text_match *tm;
47	struct tcf_em_text *conf = data;
48	struct ts_config *ts_conf;
49	int flags = 0;
50
51	if (len < sizeof(*conf) || len < (sizeof(*conf) + conf->pattern_len))
52		return -EINVAL;
53
54	if (conf->from_layer > conf->to_layer)
55		return -EINVAL;
56
57	if (conf->from_layer == conf->to_layer &&
58	    conf->from_offset > conf->to_offset)
59		return -EINVAL;
60
61retry:
62	ts_conf = textsearch_prepare(conf->algo, (u8 *) conf + sizeof(*conf),
63				     conf->pattern_len, GFP_KERNEL, flags);
64
65	if (flags & TS_AUTOLOAD)
66		rtnl_lock();
67
68	if (IS_ERR(ts_conf)) {
69		if (PTR_ERR(ts_conf) == -ENOENT && !(flags & TS_AUTOLOAD)) {
70			rtnl_unlock();
71			flags |= TS_AUTOLOAD;
72			goto retry;
73		} else
74			return PTR_ERR(ts_conf);
75	} else if (flags & TS_AUTOLOAD) {
76		textsearch_destroy(ts_conf);
77		return -EAGAIN;
78	}
79
80	tm = kmalloc(sizeof(*tm), GFP_KERNEL);
81	if (tm == NULL) {
82		textsearch_destroy(ts_conf);
83		return -ENOBUFS;
84	}
85
86	tm->from_offset = conf->from_offset;
87	tm->to_offset   = conf->to_offset;
88	tm->from_layer  = conf->from_layer;
89	tm->to_layer    = conf->to_layer;
90	tm->config      = ts_conf;
91
92	m->datalen = sizeof(*tm);
93	m->data = (unsigned long) tm;
94
95	return 0;
96}
97
98static void em_text_destroy(struct tcf_ematch *m)
99{
100	if (EM_TEXT_PRIV(m) && EM_TEXT_PRIV(m)->config) {
101		textsearch_destroy(EM_TEXT_PRIV(m)->config);
102		kfree(EM_TEXT_PRIV(m));
103	}
104}
105
106static int em_text_dump(struct sk_buff *skb, struct tcf_ematch *m)
107{
108	struct text_match *tm = EM_TEXT_PRIV(m);
109	struct tcf_em_text conf;
110
111	strncpy(conf.algo, tm->config->ops->name, sizeof(conf.algo) - 1);
112	conf.from_offset = tm->from_offset;
113	conf.to_offset = tm->to_offset;
114	conf.from_layer = tm->from_layer;
115	conf.to_layer = tm->to_layer;
116	conf.pattern_len = textsearch_get_pattern_len(tm->config);
117	conf.pad = 0;
118
119	if (nla_put_nohdr(skb, sizeof(conf), &conf) < 0)
120		goto nla_put_failure;
121	if (nla_append(skb, conf.pattern_len,
122		       textsearch_get_pattern(tm->config)) < 0)
123		goto nla_put_failure;
124	return 0;
125
126nla_put_failure:
127	return -1;
128}
129
130static struct tcf_ematch_ops em_text_ops = {
131	.kind	  = TCF_EM_TEXT,
132	.change	  = em_text_change,
133	.match	  = em_text_match,
134	.destroy  = em_text_destroy,
135	.dump	  = em_text_dump,
136	.owner	  = THIS_MODULE,
137	.link	  = LIST_HEAD_INIT(em_text_ops.link)
138};
139
140static int __init init_em_text(void)
141{
142	return tcf_em_register(&em_text_ops);
143}
144
145static void __exit exit_em_text(void)
146{
147	tcf_em_unregister(&em_text_ops);
148}
149
150MODULE_DESCRIPTION("ematch classifier for embedded text in skbs");
151MODULE_LICENSE("GPL");
152
153module_init(init_em_text);
154module_exit(exit_em_text);
155
156MODULE_ALIAS_TCF_EMATCH(TCF_EM_TEXT);
157