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
18 struct 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
em_text_match(struct sk_buff * skb,struct tcf_ematch * m,struct tcf_pkt_info * info)28 static 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 unsigned char *ptr;
33 int from, to;
34
35 ptr = tcf_get_base_ptr(skb, tm->from_layer);
36 if (!ptr)
37 return 0;
38 from = ptr - skb->data;
39 from += tm->from_offset;
40
41 ptr = tcf_get_base_ptr(skb, tm->to_layer);
42 if (!ptr)
43 return 0;
44 to = ptr - skb->data;
45 to += tm->to_offset;
46
47 return skb_find_text(skb, from, to, tm->config) != UINT_MAX;
48 }
49
em_text_change(struct net * net,void * data,int len,struct tcf_ematch * m)50 static int em_text_change(struct net *net, void *data, int len,
51 struct tcf_ematch *m)
52 {
53 struct text_match *tm;
54 struct tcf_em_text *conf = data;
55 struct ts_config *ts_conf;
56 int flags = 0;
57
58 if (len < sizeof(*conf) || len < (sizeof(*conf) + conf->pattern_len))
59 return -EINVAL;
60
61 if (conf->from_layer > conf->to_layer)
62 return -EINVAL;
63
64 if (conf->from_layer == conf->to_layer &&
65 conf->from_offset > conf->to_offset)
66 return -EINVAL;
67
68 retry:
69 ts_conf = textsearch_prepare(conf->algo, (u8 *) conf + sizeof(*conf),
70 conf->pattern_len, GFP_KERNEL, flags);
71
72 if (flags & TS_AUTOLOAD)
73 rtnl_lock();
74
75 if (IS_ERR(ts_conf)) {
76 if (PTR_ERR(ts_conf) == -ENOENT && !(flags & TS_AUTOLOAD)) {
77 rtnl_unlock();
78 flags |= TS_AUTOLOAD;
79 goto retry;
80 } else
81 return PTR_ERR(ts_conf);
82 } else if (flags & TS_AUTOLOAD) {
83 textsearch_destroy(ts_conf);
84 return -EAGAIN;
85 }
86
87 tm = kmalloc(sizeof(*tm), GFP_KERNEL);
88 if (tm == NULL) {
89 textsearch_destroy(ts_conf);
90 return -ENOBUFS;
91 }
92
93 tm->from_offset = conf->from_offset;
94 tm->to_offset = conf->to_offset;
95 tm->from_layer = conf->from_layer;
96 tm->to_layer = conf->to_layer;
97 tm->config = ts_conf;
98
99 m->datalen = sizeof(*tm);
100 m->data = (unsigned long) tm;
101
102 return 0;
103 }
104
em_text_destroy(struct tcf_ematch * m)105 static void em_text_destroy(struct tcf_ematch *m)
106 {
107 if (EM_TEXT_PRIV(m) && EM_TEXT_PRIV(m)->config) {
108 textsearch_destroy(EM_TEXT_PRIV(m)->config);
109 kfree(EM_TEXT_PRIV(m));
110 }
111 }
112
em_text_dump(struct sk_buff * skb,struct tcf_ematch * m)113 static int em_text_dump(struct sk_buff *skb, struct tcf_ematch *m)
114 {
115 struct text_match *tm = EM_TEXT_PRIV(m);
116 struct tcf_em_text conf;
117
118 strscpy(conf.algo, tm->config->ops->name);
119 conf.from_offset = tm->from_offset;
120 conf.to_offset = tm->to_offset;
121 conf.from_layer = tm->from_layer;
122 conf.to_layer = tm->to_layer;
123 conf.pattern_len = textsearch_get_pattern_len(tm->config);
124 conf.pad = 0;
125
126 if (nla_put_nohdr(skb, sizeof(conf), &conf) < 0)
127 goto nla_put_failure;
128 if (nla_append(skb, conf.pattern_len,
129 textsearch_get_pattern(tm->config)) < 0)
130 goto nla_put_failure;
131 return 0;
132
133 nla_put_failure:
134 return -1;
135 }
136
137 static struct tcf_ematch_ops em_text_ops = {
138 .kind = TCF_EM_TEXT,
139 .change = em_text_change,
140 .match = em_text_match,
141 .destroy = em_text_destroy,
142 .dump = em_text_dump,
143 .owner = THIS_MODULE,
144 .link = LIST_HEAD_INIT(em_text_ops.link)
145 };
146
init_em_text(void)147 static int __init init_em_text(void)
148 {
149 return tcf_em_register(&em_text_ops);
150 }
151
exit_em_text(void)152 static void __exit exit_em_text(void)
153 {
154 tcf_em_unregister(&em_text_ops);
155 }
156
157 MODULE_DESCRIPTION("ematch classifier for embedded text in skbs");
158 MODULE_LICENSE("GPL");
159
160 module_init(init_em_text);
161 module_exit(exit_em_text);
162
163 MODULE_ALIAS_TCF_EMATCH(TCF_EM_TEXT);
164