Skip to content

Commit

Permalink
[NETFILTER]: nf_conntrack_sip: adjust dptr and datalen after packet m…
Browse files Browse the repository at this point in the history 
…angling

After mangling the packet, the pointer to the data and the length of the data
portion may change and need to be adjusted.

Use double data pointers and a pointer to the length everywhere and add a
helper function to the NAT helper for performing the adjustments.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
  • Loading branch information
Patrick McHardy authored and David S. Miller committed Mar 26, 2008
1 parent b1ec488 commit 2a6cfb2
Show file tree
Hide file tree
Showing 3 changed files with 60 additions and 51 deletions.
6 changes: 4 additions & 2 deletions include/linux/netfilter/nf_conntrack_sip.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -24,11 +24,13 @@ enum sip_header_pos {
extern unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb,
enum ip_conntrack_info ctinfo,
struct nf_conn *ct,
const char **dptr);
const char **dptr,
unsigned int *datalen);
extern unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb,
enum ip_conntrack_info ctinfo,
struct nf_conntrack_expect *exp,
const char *dptr);
const char **dptr,
unsigned int *datalen);

extern int ct_sip_get_info(const struct nf_conn *ct, const char *dptr,
size_t dlen, unsigned int *matchoff,
Expand Down
91 changes: 48 additions & 43 deletions net/ipv4/netfilter/nf_nat_sip.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -60,15 +60,35 @@ static void addr_map_init(const struct nf_conn *ct, struct addr_map *map)
}
}

static unsigned int mangle_packet(struct sk_buff *skb,
const char **dptr, unsigned int *datalen,
unsigned int matchoff, unsigned int matchlen,
const char *buffer, unsigned int buflen)
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);

if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, matchoff, matchlen,
buffer, buflen))
return 0;

/* Reload data pointer and adjust datalen value */
*dptr = skb->data + ip_hdrlen(skb) + sizeof(struct udphdr);
*datalen += buflen - matchlen;
return 1;
}

static int map_sip_addr(struct sk_buff *skb, enum ip_conntrack_info ctinfo,
struct nf_conn *ct, const char **dptr, size_t dlen,
struct nf_conn *ct,
const char **dptr, unsigned int *datalen,
enum sip_header_pos pos, struct addr_map *map)
{
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
unsigned int matchlen, matchoff, addrlen;
char *addr;

if (ct_sip_get_info(ct, *dptr, dlen, &matchoff, &matchlen, pos) <= 0)
if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff, &matchlen,
pos) <= 0)
return 1;

if ((matchlen == map->addr[dir].srciplen ||
Expand All @@ -84,26 +104,19 @@ static int map_sip_addr(struct sk_buff *skb, enum ip_conntrack_info ctinfo,
} else
return 1;

if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo,
matchoff, matchlen, addr, addrlen))
return 0;
*dptr = skb->data + ip_hdrlen(skb) + sizeof(struct udphdr);
return 1;

return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
addr, addrlen);
}

static unsigned int ip_nat_sip(struct sk_buff *skb,
enum ip_conntrack_info ctinfo,
struct nf_conn *ct,
const char **dptr)
const char **dptr, unsigned int *datalen)
{
enum sip_header_pos pos;
struct addr_map map;
int dataoff, datalen;

dataoff = ip_hdrlen(skb) + sizeof(struct udphdr);
datalen = skb->len - dataoff;
if (datalen < sizeof("SIP/2.0") - 1)
if (*datalen < sizeof("SIP/2.0") - 1)
return NF_ACCEPT;

addr_map_init(ct, &map);
Expand All @@ -115,7 +128,7 @@ static unsigned int ip_nat_sip(struct sk_buff *skb,
* The "userinfo" and "@" components of the SIP URI MUST NOT
* be present.
*/
if (datalen >= sizeof("REGISTER") - 1 &&
if (*datalen >= sizeof("REGISTER") - 1 &&
strncmp(*dptr, "REGISTER", sizeof("REGISTER") - 1) == 0)
pos = POS_REG_REQ_URI;
else
Expand All @@ -136,51 +149,45 @@ static unsigned int ip_nat_sip(struct sk_buff *skb,
static unsigned int mangle_sip_packet(struct sk_buff *skb,
enum ip_conntrack_info ctinfo,
struct nf_conn *ct,
const char **dptr, size_t dlen,
const char **dptr, unsigned int *datalen,
char *buffer, int bufflen,
enum sip_header_pos pos)
{
unsigned int matchlen, matchoff;

if (ct_sip_get_info(ct, *dptr, dlen, &matchoff, &matchlen, pos) <= 0)
return 0;

if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo,
matchoff, matchlen, buffer, bufflen))
if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff, &matchlen,
pos) <= 0)
return 0;

/* We need to reload this. Thanks Patrick. */
*dptr = skb->data + ip_hdrlen(skb) + sizeof(struct udphdr);
return 1;
return mangle_packet(skb, dptr, datalen, matchoff, matchlen,
buffer, bufflen);
}

static int mangle_content_len(struct sk_buff *skb,
enum ip_conntrack_info ctinfo,
struct nf_conn *ct,
const char *dptr)
const char **dptr, unsigned int *datalen)
{
unsigned int dataoff, matchoff, matchlen;
unsigned int matchoff, matchlen;
char buffer[sizeof("65536")];
int bufflen;

dataoff = ip_hdrlen(skb) + sizeof(struct udphdr);

/* Get actual SDP length */
if (ct_sip_get_info(ct, dptr, skb->len - dataoff, &matchoff,
if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff,
&matchlen, POS_SDP_HEADER) > 0) {

/* since ct_sip_get_info() give us a pointer passing 'v='
we need to add 2 bytes in this count. */
int c_len = skb->len - dataoff - matchoff + 2;
int c_len = *datalen - matchoff + 2;

/* Now, update SDP length */
if (ct_sip_get_info(ct, dptr, skb->len - dataoff, &matchoff,
if (ct_sip_get_info(ct, *dptr, *datalen, &matchoff,
&matchlen, POS_CONTENT) > 0) {

bufflen = sprintf(buffer, "%u", c_len);
return nf_nat_mangle_udp_packet(skb, ct, ctinfo,
matchoff, matchlen,
buffer, bufflen);
return mangle_packet(skb, dptr, datalen,
matchoff, matchlen,
buffer, bufflen);
}
}
return 0;
Expand All @@ -190,30 +197,28 @@ static unsigned int mangle_sdp(struct sk_buff *skb,
enum ip_conntrack_info ctinfo,
struct nf_conn *ct,
__be32 newip, u_int16_t port,
const char *dptr)
const char **dptr, unsigned int *datalen)
{
char buffer[sizeof("nnn.nnn.nnn.nnn")];
unsigned int dataoff, bufflen;

dataoff = ip_hdrlen(skb) + sizeof(struct udphdr);
unsigned int bufflen;

/* Mangle owner and contact info. */
bufflen = sprintf(buffer, "%u.%u.%u.%u", NIPQUAD(newip));
if (!mangle_sip_packet(skb, ctinfo, ct, &dptr, skb->len - dataoff,
if (!mangle_sip_packet(skb, ctinfo, ct, dptr, datalen,
buffer, bufflen, POS_OWNER_IP4))
return 0;

if (!mangle_sip_packet(skb, ctinfo, ct, &dptr, skb->len - dataoff,
if (!mangle_sip_packet(skb, ctinfo, ct, dptr, datalen,
buffer, bufflen, POS_CONNECTION_IP4))
return 0;

/* Mangle media port. */
bufflen = sprintf(buffer, "%u", port);
if (!mangle_sip_packet(skb, ctinfo, ct, &dptr, skb->len - dataoff,
if (!mangle_sip_packet(skb, ctinfo, ct, dptr, datalen,
buffer, bufflen, POS_MEDIA))
return 0;

return mangle_content_len(skb, ctinfo, ct, dptr);
return mangle_content_len(skb, ctinfo, ct, dptr, datalen);
}

static void ip_nat_sdp_expect(struct nf_conn *ct,
Expand Down Expand Up @@ -242,7 +247,7 @@ static void ip_nat_sdp_expect(struct nf_conn *ct,
static unsigned int ip_nat_sdp(struct sk_buff *skb,
enum ip_conntrack_info ctinfo,
struct nf_conntrack_expect *exp,
const char *dptr)
const char **dptr, unsigned int *datalen)
{
struct nf_conn *ct = exp->master;
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
Expand Down Expand Up @@ -275,7 +280,7 @@ static unsigned int ip_nat_sdp(struct sk_buff *skb,
if (port == 0)
return NF_DROP;

if (!mangle_sdp(skb, ctinfo, ct, newip, port, dptr)) {
if (!mangle_sdp(skb, ctinfo, ct, newip, port, dptr, datalen)) {
nf_ct_unexpect_related(exp);
return NF_DROP;
}
Expand Down
14 changes: 8 additions & 6 deletions net/netfilter/nf_conntrack_sip.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -39,13 +39,15 @@ MODULE_PARM_DESC(sip_timeout, "timeout for the master SIP session");
unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb,
enum ip_conntrack_info ctinfo,
struct nf_conn *ct,
const char **dptr) __read_mostly;
const char **dptr,
unsigned int *datalen) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_sip_hook);

unsigned int (*nf_nat_sdp_hook)(struct sk_buff *skb,
enum ip_conntrack_info ctinfo,
struct nf_conntrack_expect *exp,
const char *dptr) __read_mostly;
const char **dptr,
unsigned int *datalen) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_sdp_hook);

static int digits_len(const struct nf_conn *, const char *, const char *, int *);
Expand Down Expand Up @@ -369,7 +371,7 @@ static int set_expected_rtp(struct sk_buff *skb,
enum ip_conntrack_info ctinfo,
union nf_inet_addr *addr,
__be16 port,
const char *dptr)
const char **dptr, unsigned int *datalen)
{
struct nf_conntrack_expect *exp;
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
Expand All @@ -386,7 +388,7 @@ static int set_expected_rtp(struct sk_buff *skb,

nf_nat_sdp = rcu_dereference(nf_nat_sdp_hook);
if (nf_nat_sdp && ct->status & IPS_NAT_MASK)
ret = nf_nat_sdp(skb, ctinfo, exp, dptr);
ret = nf_nat_sdp(skb, ctinfo, exp, dptr, datalen);
else {
if (nf_ct_expect_related(exp) != 0)
ret = NF_DROP;
Expand Down Expand Up @@ -429,7 +431,7 @@ static int sip_help(struct sk_buff *skb,

nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
if (nf_nat_sip && ct->status & IPS_NAT_MASK) {
if (!nf_nat_sip(skb, ctinfo, ct, &dptr)) {
if (!nf_nat_sip(skb, ctinfo, ct, &dptr, &datalen)) {
ret = NF_DROP;
goto out;
}
Expand Down Expand Up @@ -466,7 +468,7 @@ static int sip_help(struct sk_buff *skb,
goto out;
}
ret = set_expected_rtp(skb, ct, ctinfo, &addr,
htons(port), dptr);
htons(port), &dptr, &datalen);
}
}
out:
Expand Down

0 comments on commit 2a6cfb2

Please sign in to comment.