[mirror_ubuntu-bionic-kernel.git] / net / ipv6 / netfilter / ip6t_frag.c

/* Kernel module to match FRAG parameters. */

/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ipv6.h>
#include <linux/types.h>
#include <net/checksum.h>
#include <net/ipv6.h>

#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_frag.h>

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("IPv6 FRAG match");
MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");

#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif

/* Returns 1 if the id is matched by the range, 0 otherwise */
static inline int
id_match(u_int32_t min, u_int32_t max, u_int32_t id, int invert)
{
       int r=0;
       DEBUGP("frag id_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',
              min,id,max);
       r=(id >= min && id <= max) ^ invert;
       DEBUGP(" result %s\n",r? "PASS" : "FAILED");
       return r;
}

static int
match(const struct sk_buff *skb,
      const struct net_device *in,
      const struct net_device *out,
      const void *matchinfo,
      int offset,
      unsigned int protoff,
      int *hotdrop)
{
       struct frag_hdr _frag, *fh = NULL;
       const struct ip6t_frag *fraginfo = matchinfo;
       unsigned int temp;
       int len;
       u8 nexthdr;
       unsigned int ptr;
       unsigned int hdrlen = 0;

       /* type of the 1st exthdr */
       nexthdr = skb->nh.ipv6h->nexthdr;
       /* pointer to the 1st exthdr */
       ptr = sizeof(struct ipv6hdr);
       /* available length */
       len = skb->len - ptr;
       temp = 0;

        while (ip6t_ext_hdr(nexthdr)) {
               struct ipv6_opt_hdr _hdr, *hp;

              DEBUGP("ipv6_frag header iteration \n");

              /* Is there enough space for the next ext header? */
                if (len < (int)sizeof(struct ipv6_opt_hdr))
                        return 0;
              /* No more exthdr -> evaluate */
                if (nexthdr == NEXTHDR_NONE) {
                     break;
              }
              /* ESP -> evaluate */
                if (nexthdr == NEXTHDR_ESP) {
                     break;
              }

	      hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
	      BUG_ON(hp == NULL);

              /* Calculate the header length */
                if (nexthdr == NEXTHDR_FRAGMENT) {
                        hdrlen = 8;
                } else if (nexthdr == NEXTHDR_AUTH)
                        hdrlen = (hp->hdrlen+2)<<2;
                else
                        hdrlen = ipv6_optlen(hp);

              /* FRAG -> evaluate */
                if (nexthdr == NEXTHDR_FRAGMENT) {
                     temp |= MASK_FRAGMENT;
                     break;
              }


              /* set the flag */
              switch (nexthdr){
                     case NEXTHDR_HOP:
                     case NEXTHDR_ROUTING:
                     case NEXTHDR_FRAGMENT:
                     case NEXTHDR_AUTH:
                     case NEXTHDR_DEST:
                            break;
                     default:
                            DEBUGP("ipv6_frag match: unknown nextheader %u\n",nexthdr);
                            return 0;
                            break;
              }

                nexthdr = hp->nexthdr;
                len -= hdrlen;
                ptr += hdrlen;
		if ( ptr > skb->len ) {
			DEBUGP("ipv6_frag: new pointer too large! \n");
			break;
		}
        }

       /* FRAG header not found */
       if ( temp != MASK_FRAGMENT ) return 0;

       if (len < sizeof(struct frag_hdr)){
	       *hotdrop = 1;
       		return 0;
       }

       fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag);
       BUG_ON(fh == NULL);

       DEBUGP("INFO %04X ", fh->frag_off);
       DEBUGP("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7);
       DEBUGP("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6);
       DEBUGP("MF %04X ", fh->frag_off & htons(IP6_MF));
       DEBUGP("ID %u %08X\n", ntohl(fh->identification),
	      ntohl(fh->identification));

       DEBUGP("IPv6 FRAG id %02X ",
       		(id_match(fraginfo->ids[0], fraginfo->ids[1],
                           ntohl(fh->identification),
                           !!(fraginfo->invflags & IP6T_FRAG_INV_IDS))));
       DEBUGP("res %02X %02X%04X %02X ", 
       		(fraginfo->flags & IP6T_FRAG_RES), fh->reserved,
		ntohs(fh->frag_off) & 0x6,
       		!((fraginfo->flags & IP6T_FRAG_RES)
			&& (fh->reserved || (ntohs(fh->frag_off) & 0x06))));
       DEBUGP("first %02X %02X %02X ", 
       		(fraginfo->flags & IP6T_FRAG_FST),
		ntohs(fh->frag_off) & ~0x7,
       		!((fraginfo->flags & IP6T_FRAG_FST)
			&& (ntohs(fh->frag_off) & ~0x7)));
       DEBUGP("mf %02X %02X %02X ", 
       		(fraginfo->flags & IP6T_FRAG_MF),
		ntohs(fh->frag_off) & IP6_MF,
       		!((fraginfo->flags & IP6T_FRAG_MF)
			&& !((ntohs(fh->frag_off) & IP6_MF))));
       DEBUGP("last %02X %02X %02X\n", 
       		(fraginfo->flags & IP6T_FRAG_NMF),
		ntohs(fh->frag_off) & IP6_MF,
       		!((fraginfo->flags & IP6T_FRAG_NMF)
			&& (ntohs(fh->frag_off) & IP6_MF)));

       return (fh != NULL)
       		&&
       		(id_match(fraginfo->ids[0], fraginfo->ids[1],
			  ntohl(fh->identification),
                           !!(fraginfo->invflags & IP6T_FRAG_INV_IDS)))
		&&
		!((fraginfo->flags & IP6T_FRAG_RES)
			&& (fh->reserved || (ntohs(fh->frag_off) & 0x6)))
		&&
		!((fraginfo->flags & IP6T_FRAG_FST)
			&& (ntohs(fh->frag_off) & ~0x7))
		&&
		!((fraginfo->flags & IP6T_FRAG_MF)
			&& !(ntohs(fh->frag_off) & IP6_MF))
		&&
		!((fraginfo->flags & IP6T_FRAG_NMF)
			&& (ntohs(fh->frag_off) & IP6_MF));
}

/* Called when user tries to insert an entry of this type. */
static int
checkentry(const char *tablename,
          const struct ip6t_ip6 *ip,
          void *matchinfo,
          unsigned int matchinfosize,
          unsigned int hook_mask)
{
       const struct ip6t_frag *fraginfo = matchinfo;

       if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_frag))) {
              DEBUGP("ip6t_frag: matchsize %u != %u\n",
                      matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_frag)));
              return 0;
       }
       if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
              DEBUGP("ip6t_frag: unknown flags %X\n",
                      fraginfo->invflags);
              return 0;
       }

       return 1;
}

static struct ip6t_match frag_match = {
	.name		= "frag",
	.match		= &match,
	.checkentry	= &checkentry,
	.me		= THIS_MODULE,
};

static int __init init(void)
{
       return ip6t_register_match(&frag_match);
}

static void __exit cleanup(void)
{
       ip6t_unregister_match(&frag_match);
}

module_init(init);
module_exit(cleanup);
Commit	Line	Data
1da177e4 LT	1	/* Kernel module to match FRAG parameters. */
	2
	3	/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License version 2 as
	7	* published by the Free Software Foundation.
	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/skbuff.h>
	12	#include <linux/ipv6.h>
	13	#include <linux/types.h>
	14	#include <net/checksum.h>
	15	#include <net/ipv6.h>
	16
	17	#include <linux/netfilter_ipv6/ip6_tables.h>
	18	#include <linux/netfilter_ipv6/ip6t_frag.h>
	19
	20	MODULE_LICENSE("GPL");
	21	MODULE_DESCRIPTION("IPv6 FRAG match");
	22	MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
	23
	24	#if 0
	25	#define DEBUGP printk
	26	#else
	27	#define DEBUGP(format, args...)
	28	#endif
	29
	30	/* Returns 1 if the id is matched by the range, 0 otherwise */
	31	static inline int
	32	id_match(u_int32_t min, u_int32_t max, u_int32_t id, int invert)
	33	{
	34	int r=0;
	35	DEBUGP("frag id_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',
	36	min,id,max);
	37	r=(id >= min && id <= max) ^ invert;
	38	DEBUGP(" result %s\n",r? "PASS" : "FAILED");
	39	return r;
	40	}
	41
	42	static int
	43	match(const struct sk_buff *skb,
	44	const struct net_device *in,
	45	const struct net_device *out,
	46	const void *matchinfo,
	47	int offset,
	48	unsigned int protoff,
	49	int *hotdrop)
	50	{
	51	struct frag_hdr _frag, *fh = NULL;
	52	const struct ip6t_frag *fraginfo = matchinfo;
	53	unsigned int temp;
	54	int len;
	55	u8 nexthdr;
	56	unsigned int ptr;
	57	unsigned int hdrlen = 0;
	58
	59	/* type of the 1st exthdr */
	60	nexthdr = skb->nh.ipv6h->nexthdr;
	61	/* pointer to the 1st exthdr */
	62	ptr = sizeof(struct ipv6hdr);
	63	/* available length */
	64	len = skb->len - ptr;
65	temp = 0;
66
67	while (ip6t_ext_hdr(nexthdr)) {
68	struct ipv6_opt_hdr _hdr, *hp;
69
70	DEBUGP("ipv6_frag header iteration \n");
71
72	/* Is there enough space for the next ext header? */
73	if (len < (int)sizeof(struct ipv6_opt_hdr))
74	return 0;
75	/* No more exthdr -> evaluate */
76	if (nexthdr == NEXTHDR_NONE) {
77	break;
78	}
79	/* ESP -> evaluate */
80	if (nexthdr == NEXTHDR_ESP) {
81	break;
82	}
83
84	hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
85	BUG_ON(hp == NULL);
86
87	/* Calculate the header length */
88	if (nexthdr == NEXTHDR_FRAGMENT) {
89	hdrlen = 8;
90	} else if (nexthdr == NEXTHDR_AUTH)
91	hdrlen = (hp->hdrlen+2)<<2;
92	else
93	hdrlen = ipv6_optlen(hp);
94
95	/* FRAG -> evaluate */
96	if (nexthdr == NEXTHDR_FRAGMENT) {
97	temp \|= MASK_FRAGMENT;
98	break;
99	}
100
101
102	/* set the flag */
103	switch (nexthdr){
104	case NEXTHDR_HOP:
105	case NEXTHDR_ROUTING:
106	case NEXTHDR_FRAGMENT:
107	case NEXTHDR_AUTH:
108	case NEXTHDR_DEST:
109	break;
110	default:
111	DEBUGP("ipv6_frag match: unknown nextheader %u\n",nexthdr);
112	return 0;
113	break;
114	}
115
116	nexthdr = hp->nexthdr;
117	len -= hdrlen;
118	ptr += hdrlen;
119	if ( ptr > skb->len ) {
120	DEBUGP("ipv6_frag: new pointer too large! \n");
121	break;
122	}
123	}
124
125	/* FRAG header not found */
126	if ( temp != MASK_FRAGMENT ) return 0;
127
128	if (len < sizeof(struct frag_hdr)){
129	*hotdrop = 1;
130	return 0;
131	}
132
133	fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag);
134	BUG_ON(fh == NULL);
135
136	DEBUGP("INFO %04X ", fh->frag_off);
137	DEBUGP("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7);
138	DEBUGP("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6);
139	DEBUGP("MF %04X ", fh->frag_off & htons(IP6_MF));
140	DEBUGP("ID %u %08X\n", ntohl(fh->identification),
141	ntohl(fh->identification));
142
143	DEBUGP("IPv6 FRAG id %02X ",
144	(id_match(fraginfo->ids[0], fraginfo->ids[1],
145	ntohl(fh->identification),
146	!!(fraginfo->invflags & IP6T_FRAG_INV_IDS))));
147	DEBUGP("res %02X %02X%04X %02X ",
148	(fraginfo->flags & IP6T_FRAG_RES), fh->reserved,
149	ntohs(fh->frag_off) & 0x6,
150	!((fraginfo->flags & IP6T_FRAG_RES)
151	&& (fh->reserved \|\| (ntohs(fh->frag_off) & 0x06))));
152	DEBUGP("first %02X %02X %02X ",
153	(fraginfo->flags & IP6T_FRAG_FST),
154	ntohs(fh->frag_off) & ~0x7,
155	!((fraginfo->flags & IP6T_FRAG_FST)
156	&& (ntohs(fh->frag_off) & ~0x7)));
157	DEBUGP("mf %02X %02X %02X ",
158	(fraginfo->flags & IP6T_FRAG_MF),
159	ntohs(fh->frag_off) & IP6_MF,
160	!((fraginfo->flags & IP6T_FRAG_MF)
161	&& !((ntohs(fh->frag_off) & IP6_MF))));
162	DEBUGP("last %02X %02X %02X\n",
163	(fraginfo->flags & IP6T_FRAG_NMF),
164	ntohs(fh->frag_off) & IP6_MF,
165	!((fraginfo->flags & IP6T_FRAG_NMF)
166	&& (ntohs(fh->frag_off) & IP6_MF)));
167
168	return (fh != NULL)
169	&&
170	(id_match(fraginfo->ids[0], fraginfo->ids[1],
171	ntohl(fh->identification),
172	!!(fraginfo->invflags & IP6T_FRAG_INV_IDS)))
173	&&
174	!((fraginfo->flags & IP6T_FRAG_RES)
175	&& (fh->reserved \|\| (ntohs(fh->frag_off) & 0x6)))
176	&&
177	!((fraginfo->flags & IP6T_FRAG_FST)
178	&& (ntohs(fh->frag_off) & ~0x7))
179	&&
180	!((fraginfo->flags & IP6T_FRAG_MF)
181	&& !(ntohs(fh->frag_off) & IP6_MF))
182	&&
183	!((fraginfo->flags & IP6T_FRAG_NMF)
184	&& (ntohs(fh->frag_off) & IP6_MF));
185	}
186
187	/* Called when user tries to insert an entry of this type. */
188	static int
189	checkentry(const char *tablename,
190	const struct ip6t_ip6 *ip,
191	void *matchinfo,
192	unsigned int matchinfosize,
193	unsigned int hook_mask)
194	{
195	const struct ip6t_frag *fraginfo = matchinfo;
196
197	if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_frag))) {
198	DEBUGP("ip6t_frag: matchsize %u != %u\n",
199	matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_frag)));
200	return 0;
201	}
202	if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
203	DEBUGP("ip6t_frag: unknown flags %X\n",
204	fraginfo->invflags);
205	return 0;
206	}
207
208	return 1;
209	}
210
211	static struct ip6t_match frag_match = {
212	.name = "frag",
213	.match = &match,
214	.checkentry = &checkentry,
215	.me = THIS_MODULE,
216	};
217
218	static int __init init(void)
219	{
220	return ip6t_register_match(&frag_match);
221	}
222
223	static void __exit cleanup(void)
224	{
225	ip6t_unregister_match(&frag_match);
226	}
227
228	module_init(init);
229	module_exit(cleanup);