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gre: Move utility functions to common headers
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Several of the GRE functions defined in net/ipv4/ip_gre.c are usable
for IPv6 GRE implementation (that is they are protocol agnostic).

These include:
  - GRE flag handling functions are move to gre.h
  - GRE build_header is moved to gre.h and renamed gre_build_header
  - parse_gre_header is moved to gre_demux.c and renamed gre_parse_header
  - iptunnel_pull_header is taken out of gre_parse_header. This is now
    done by caller. The header length is returned from gre_parse_header
    in an int* argument.

Signed-off-by: Tom Herbert <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@tomratbert @davem330
tomratbert authored and davem330 committed May 2, 2016
1 parent 0d3c703 commit 95f5c64
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Showing 3 changed files with 144 additions and 129 deletions.
60 changes: 60 additions & 0 deletions include/net/gre.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -25,4 +25,64 @@ int gre_del_protocol(const struct gre_protocol *proto, u8 version);

struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
u8 name_assign_type);
int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
bool *csum_err, int *hdr_len);

static inline int gre_calc_hlen(__be16 o_flags)
{
int addend = 4;

if (o_flags & TUNNEL_CSUM)
addend += 4;
if (o_flags & TUNNEL_KEY)
addend += 4;
if (o_flags & TUNNEL_SEQ)
addend += 4;
return addend;
}

static inline __be16 gre_flags_to_tnl_flags(__be16 flags)
{
__be16 tflags = 0;

if (flags & GRE_CSUM)
tflags |= TUNNEL_CSUM;
if (flags & GRE_ROUTING)
tflags |= TUNNEL_ROUTING;
if (flags & GRE_KEY)
tflags |= TUNNEL_KEY;
if (flags & GRE_SEQ)
tflags |= TUNNEL_SEQ;
if (flags & GRE_STRICT)
tflags |= TUNNEL_STRICT;
if (flags & GRE_REC)
tflags |= TUNNEL_REC;
if (flags & GRE_VERSION)
tflags |= TUNNEL_VERSION;

return tflags;
}

static inline __be16 gre_tnl_flags_to_gre_flags(__be16 tflags)
{
__be16 flags = 0;

if (tflags & TUNNEL_CSUM)
flags |= GRE_CSUM;
if (tflags & TUNNEL_ROUTING)
flags |= GRE_ROUTING;
if (tflags & TUNNEL_KEY)
flags |= GRE_KEY;
if (tflags & TUNNEL_SEQ)
flags |= GRE_SEQ;
if (tflags & TUNNEL_STRICT)
flags |= GRE_STRICT;
if (tflags & TUNNEL_REC)
flags |= GRE_REC;
if (tflags & TUNNEL_VERSION)
flags |= GRE_VERSION;

return flags;
}

#endif
64 changes: 64 additions & 0 deletions net/ipv4/gre_demux.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,70 @@ int gre_del_protocol(const struct gre_protocol *proto, u8 version)
}
EXPORT_SYMBOL_GPL(gre_del_protocol);

int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
bool *csum_err, int *ret_hdr_len)
{
const struct gre_base_hdr *greh;
__be32 *options;
int hdr_len;

if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
return -EINVAL;

greh = (struct gre_base_hdr *)skb_transport_header(skb);
if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
return -EINVAL;

tpi->flags = gre_flags_to_tnl_flags(greh->flags);
hdr_len = gre_calc_hlen(tpi->flags);

if (!pskb_may_pull(skb, hdr_len))
return -EINVAL;

greh = (struct gre_base_hdr *)skb_transport_header(skb);
tpi->proto = greh->protocol;

options = (__be32 *)(greh + 1);
if (greh->flags & GRE_CSUM) {
if (skb_checksum_simple_validate(skb)) {
*csum_err = true;
return -EINVAL;
}

skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
null_compute_pseudo);
options++;
}

if (greh->flags & GRE_KEY) {
tpi->key = *options;
options++;
} else {
tpi->key = 0;
}
if (unlikely(greh->flags & GRE_SEQ)) {
tpi->seq = *options;
options++;
} else {
tpi->seq = 0;
}
/* WCCP version 1 and 2 protocol decoding.
* - Change protocol to IP
* - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
*/
if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
tpi->proto = htons(ETH_P_IP);
if ((*(u8 *)options & 0xF0) != 0x40) {
hdr_len += 4;
if (!pskb_may_pull(skb, hdr_len))
return -EINVAL;
}
}
*ret_hdr_len = hdr_len;
return 0;
}
EXPORT_SYMBOL(gre_parse_header);

static int gre_rcv(struct sk_buff *skb)
{
const struct gre_protocol *proto;
Expand Down
149 changes: 20 additions & 129 deletions net/ipv4/ip_gre.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -122,125 +122,6 @@ static int ipgre_tunnel_init(struct net_device *dev);
static int ipgre_net_id __read_mostly;
static int gre_tap_net_id __read_mostly;

static int ip_gre_calc_hlen(__be16 o_flags)
{
int addend = 4;

if (o_flags & TUNNEL_CSUM)
addend += 4;
if (o_flags & TUNNEL_KEY)
addend += 4;
if (o_flags & TUNNEL_SEQ)
addend += 4;
return addend;
}

static __be16 gre_flags_to_tnl_flags(__be16 flags)
{
__be16 tflags = 0;

if (flags & GRE_CSUM)
tflags |= TUNNEL_CSUM;
if (flags & GRE_ROUTING)
tflags |= TUNNEL_ROUTING;
if (flags & GRE_KEY)
tflags |= TUNNEL_KEY;
if (flags & GRE_SEQ)
tflags |= TUNNEL_SEQ;
if (flags & GRE_STRICT)
tflags |= TUNNEL_STRICT;
if (flags & GRE_REC)
tflags |= TUNNEL_REC;
if (flags & GRE_VERSION)
tflags |= TUNNEL_VERSION;

return tflags;
}

static __be16 tnl_flags_to_gre_flags(__be16 tflags)
{
__be16 flags = 0;

if (tflags & TUNNEL_CSUM)
flags |= GRE_CSUM;
if (tflags & TUNNEL_ROUTING)
flags |= GRE_ROUTING;
if (tflags & TUNNEL_KEY)
flags |= GRE_KEY;
if (tflags & TUNNEL_SEQ)
flags |= GRE_SEQ;
if (tflags & TUNNEL_STRICT)
flags |= GRE_STRICT;
if (tflags & TUNNEL_REC)
flags |= GRE_REC;
if (tflags & TUNNEL_VERSION)
flags |= GRE_VERSION;

return flags;
}

static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
bool *csum_err)
{
const struct gre_base_hdr *greh;
__be32 *options;
int hdr_len;

if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr))))
return -EINVAL;

greh = (struct gre_base_hdr *)skb_transport_header(skb);
if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
return -EINVAL;

tpi->flags = gre_flags_to_tnl_flags(greh->flags);
hdr_len = ip_gre_calc_hlen(tpi->flags);

if (!pskb_may_pull(skb, hdr_len))
return -EINVAL;

greh = (struct gre_base_hdr *)skb_transport_header(skb);
tpi->proto = greh->protocol;

options = (__be32 *)(greh + 1);
if (greh->flags & GRE_CSUM) {
if (skb_checksum_simple_validate(skb)) {
*csum_err = true;
return -EINVAL;
}

skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
null_compute_pseudo);
options++;
}

if (greh->flags & GRE_KEY) {
tpi->key = *options;
options++;
} else {
tpi->key = 0;
}
if (unlikely(greh->flags & GRE_SEQ)) {
tpi->seq = *options;
options++;
} else {
tpi->seq = 0;
}
/* WCCP version 1 and 2 protocol decoding.
* - Change protocol to IP
* - When dealing with WCCPv2, Skip extra 4 bytes in GRE header
*/
if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) {
tpi->proto = htons(ETH_P_IP);
if ((*(u8 *)options & 0xF0) != 0x40) {
hdr_len += 4;
if (!pskb_may_pull(skb, hdr_len))
return -EINVAL;
}
}
return iptunnel_pull_header(skb, hdr_len, tpi->proto, false);
}

static void ipgre_err(struct sk_buff *skb, u32 info,
const struct tnl_ptk_info *tpi)
{
Expand Down Expand Up @@ -340,12 +221,16 @@ static void gre_err(struct sk_buff *skb, u32 info)
const int code = icmp_hdr(skb)->code;
struct tnl_ptk_info tpi;
bool csum_err = false;
int hdr_len;

if (parse_gre_header(skb, &tpi, &csum_err)) {
if (gre_parse_header(skb, &tpi, &csum_err, &hdr_len)) {
if (!csum_err) /* ignore csum errors. */
return;
}

if (iptunnel_pull_header(skb, hdr_len, tpi.proto, false))
return;

if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
ipv4_update_pmtu(skb, dev_net(skb->dev), info,
skb->dev->ifindex, 0, IPPROTO_GRE, 0);
Expand Down Expand Up @@ -419,6 +304,7 @@ static int gre_rcv(struct sk_buff *skb)
{
struct tnl_ptk_info tpi;
bool csum_err = false;
int hdr_len;

#ifdef CONFIG_NET_IPGRE_BROADCAST
if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
Expand All @@ -428,7 +314,10 @@ static int gre_rcv(struct sk_buff *skb)
}
#endif

if (parse_gre_header(skb, &tpi, &csum_err) < 0)
if (gre_parse_header(skb, &tpi, &csum_err, &hdr_len) < 0)
goto drop;

if (iptunnel_pull_header(skb, hdr_len, tpi.proto, false))
goto drop;

if (ipgre_rcv(skb, &tpi) == PACKET_RCVD)
Expand Down Expand Up @@ -460,7 +349,7 @@ static void build_header(struct sk_buff *skb, int hdr_len, __be16 flags,

skb_reset_transport_header(skb);
greh = (struct gre_base_hdr *)skb->data;
greh->flags = tnl_flags_to_gre_flags(flags);
greh->flags = gre_tnl_flags_to_gre_flags(flags);
greh->protocol = proto;

if (flags & (TUNNEL_KEY | TUNNEL_CSUM | TUNNEL_SEQ)) {
Expand Down Expand Up @@ -552,7 +441,7 @@ static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev)
fl.saddr);
}

tunnel_hlen = ip_gre_calc_hlen(key->tun_flags);
tunnel_hlen = gre_calc_hlen(key->tun_flags);

min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
+ tunnel_hlen + sizeof(struct iphdr);
Expand Down Expand Up @@ -694,8 +583,8 @@ static int ipgre_tunnel_ioctl(struct net_device *dev,
if (err)
return err;

p.i_flags = tnl_flags_to_gre_flags(p.i_flags);
p.o_flags = tnl_flags_to_gre_flags(p.o_flags);
p.i_flags = gre_tnl_flags_to_gre_flags(p.i_flags);
p.o_flags = gre_tnl_flags_to_gre_flags(p.o_flags);

if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
return -EFAULT;
Expand Down Expand Up @@ -739,7 +628,7 @@ static int ipgre_header(struct sk_buff *skb, struct net_device *dev,

iph = (struct iphdr *)skb_push(skb, t->hlen + sizeof(*iph));
greh = (struct gre_base_hdr *)(iph+1);
greh->flags = tnl_flags_to_gre_flags(t->parms.o_flags);
greh->flags = gre_tnl_flags_to_gre_flags(t->parms.o_flags);
greh->protocol = htons(type);

memcpy(iph, &t->parms.iph, sizeof(struct iphdr));
Expand Down Expand Up @@ -840,7 +729,7 @@ static void __gre_tunnel_init(struct net_device *dev)
int t_hlen;

tunnel = netdev_priv(dev);
tunnel->tun_hlen = ip_gre_calc_hlen(tunnel->parms.o_flags);
tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);
tunnel->parms.iph.protocol = IPPROTO_GRE;

tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen;
Expand Down Expand Up @@ -1155,8 +1044,10 @@ static int ipgre_fill_info(struct sk_buff *skb, const struct net_device *dev)
struct ip_tunnel_parm *p = &t->parms;

if (nla_put_u32(skb, IFLA_GRE_LINK, p->link) ||
nla_put_be16(skb, IFLA_GRE_IFLAGS, tnl_flags_to_gre_flags(p->i_flags)) ||
nla_put_be16(skb, IFLA_GRE_OFLAGS, tnl_flags_to_gre_flags(p->o_flags)) ||
nla_put_be16(skb, IFLA_GRE_IFLAGS,
gre_tnl_flags_to_gre_flags(p->i_flags)) ||
nla_put_be16(skb, IFLA_GRE_OFLAGS,
gre_tnl_flags_to_gre_flags(p->o_flags)) ||
nla_put_be32(skb, IFLA_GRE_IKEY, p->i_key) ||
nla_put_be32(skb, IFLA_GRE_OKEY, p->o_key) ||
nla_put_in_addr(skb, IFLA_GRE_LOCAL, p->iph.saddr) ||
Expand Down

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