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d19da360ee
linux-next/net/core/flow_dissector.c
David Miller 3d9f773cf2 bpf: Use bpf_prog_run_pin_on_cpu() at simple call sites. 
All of these cases are strictly of the form:

	preempt_disable();
	BPF_PROG_RUN(...);
	preempt_enable();

Replace this with bpf_prog_run_pin_on_cpu() which wraps BPF_PROG_RUN()
with:

	migrate_disable();
	BPF_PROG_RUN(...);
	migrate_enable();

On non RT enabled kernels this maps to preempt_disable/enable() and on RT
enabled kernels this solely prevents migration, which is sufficient as
there is no requirement to prevent reentrancy to any BPF program from a
preempting task. The only requirement is that the program stays on the same
CPU.

Therefore, this is a trivially correct transformation.

The seccomp loop does not need protection over the loop. It only needs
protection per BPF filter program

[ tglx: Converted to bpf_prog_run_pin_on_cpu() ]

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200224145643.691493094@linutronix.de
2020-02-24 16:20:09 -08:00

1843 lines
49 KiB
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// SPDX-License-Identifier: GPL-2.0-only
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/export.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/if_vlan.h>
#include <net/dsa.h>
#include <net/dst_metadata.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/gre.h>
#include <net/pptp.h>
#include <net/tipc.h>
#include <linux/igmp.h>
#include <linux/icmp.h>
#include <linux/sctp.h>
#include <linux/dccp.h>
#include <linux/if_tunnel.h>
#include <linux/if_pppox.h>
#include <linux/ppp_defs.h>
#include <linux/stddef.h>
#include <linux/if_ether.h>
#include <linux/mpls.h>
#include <linux/tcp.h>
#include <net/flow_dissector.h>
#include <scsi/fc/fc_fcoe.h>
#include <uapi/linux/batadv_packet.h>
#include <linux/bpf.h>
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_labels.h>
#endif
static DEFINE_MUTEX(flow_dissector_mutex);
static void dissector_set_key(struct flow_dissector *flow_dissector,
enum flow_dissector_key_id key_id)
{
flow_dissector->used_keys |= (1 << key_id);
}
void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
const struct flow_dissector_key *key,
unsigned int key_count)
{
unsigned int i;
memset(flow_dissector, 0, sizeof(*flow_dissector));
for (i = 0; i < key_count; i++, key++) {
/* User should make sure that every key target offset is withing
* boundaries of unsigned short.
*/
BUG_ON(key->offset > USHRT_MAX);
BUG_ON(dissector_uses_key(flow_dissector,
key->key_id));
dissector_set_key(flow_dissector, key->key_id);
flow_dissector->offset[key->key_id] = key->offset;
}
/* Ensure that the dissector always includes control and basic key.
* That way we are able to avoid handling lack of these in fast path.
*/
BUG_ON(!dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_CONTROL));
BUG_ON(!dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_BASIC));
}
EXPORT_SYMBOL(skb_flow_dissector_init);
int skb_flow_dissector_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
u32 prog_id, prog_cnt = 0, flags = 0;
struct bpf_prog *attached;
struct net *net;
if (attr->query.query_flags)
return -EINVAL;
net = get_net_ns_by_fd(attr->query.target_fd);
if (IS_ERR(net))
return PTR_ERR(net);
rcu_read_lock();
attached = rcu_dereference(net->flow_dissector_prog);
if (attached) {
prog_cnt = 1;
prog_id = attached->aux->id;
}
rcu_read_unlock();
put_net(net);
if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
return -EFAULT;
if (copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt)))
return -EFAULT;
if (!attr->query.prog_cnt || !prog_ids || !prog_cnt)
return 0;
if (copy_to_user(prog_ids, &prog_id, sizeof(u32)))
return -EFAULT;
return 0;
}
int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
struct bpf_prog *prog)
{
struct bpf_prog *attached;
struct net *net;
int ret = 0;
net = current->nsproxy->net_ns;
mutex_lock(&flow_dissector_mutex);
if (net == &init_net) {
/* BPF flow dissector in the root namespace overrides
* any per-net-namespace one. When attaching to root,
* make sure we don't have any BPF program attached
* to the non-root namespaces.
*/
struct net *ns;
for_each_net(ns) {
if (ns == &init_net)
continue;
if (rcu_access_pointer(ns->flow_dissector_prog)) {
ret = -EEXIST;
goto out;
}
}
} else {
/* Make sure root flow dissector is not attached
* when attaching to the non-root namespace.
*/
if (rcu_access_pointer(init_net.flow_dissector_prog)) {
ret = -EEXIST;
goto out;
}
}
attached = rcu_dereference_protected(net->flow_dissector_prog,
lockdep_is_held(&flow_dissector_mutex));
if (attached == prog) {
/* The same program cannot be attached twice */
ret = -EINVAL;
goto out;
}
rcu_assign_pointer(net->flow_dissector_prog, prog);
if (attached)
bpf_prog_put(attached);
out:
mutex_unlock(&flow_dissector_mutex);
return ret;
}
int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr)
{
struct bpf_prog *attached;
struct net *net;
net = current->nsproxy->net_ns;
mutex_lock(&flow_dissector_mutex);
attached = rcu_dereference_protected(net->flow_dissector_prog,
lockdep_is_held(&flow_dissector_mutex));
if (!attached) {
mutex_unlock(&flow_dissector_mutex);
return -ENOENT;
}
RCU_INIT_POINTER(net->flow_dissector_prog, NULL);
bpf_prog_put(attached);
mutex_unlock(&flow_dissector_mutex);
return 0;
}
/**
* __skb_flow_get_ports - extract the upper layer ports and return them
* @skb: sk_buff to extract the ports from
* @thoff: transport header offset
* @ip_proto: protocol for which to get port offset
* @data: raw buffer pointer to the packet, if NULL use skb->data
* @hlen: packet header length, if @data is NULL use skb_headlen(skb)
*
* The function will try to retrieve the ports at offset thoff + poff where poff
* is the protocol port offset returned from proto_ports_offset
*/
__be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
void *data, int hlen)
{
int poff = proto_ports_offset(ip_proto);
if (!data) {
data = skb->data;
hlen = skb_headlen(skb);
}
if (poff >= 0) {
__be32 *ports, _ports;
ports = __skb_header_pointer(skb, thoff + poff,
sizeof(_ports), data, hlen, &_ports);
if (ports)
return *ports;
}
return 0;
}
EXPORT_SYMBOL(__skb_flow_get_ports);
static bool icmp_has_id(u8 type)
{
switch (type) {
case ICMP_ECHO:
case ICMP_ECHOREPLY:
case ICMP_TIMESTAMP:
case ICMP_TIMESTAMPREPLY:
case ICMPV6_ECHO_REQUEST:
case ICMPV6_ECHO_REPLY:
return true;
}
return false;
}
/**
* skb_flow_get_icmp_tci - extract ICMP(6) Type, Code and Identifier fields
* @skb: sk_buff to extract from
* @key_icmp: struct flow_dissector_key_icmp to fill
* @data: raw buffer pointer to the packet
* @thoff: offset to extract at
* @hlen: packet header length
*/
void skb_flow_get_icmp_tci(const struct sk_buff *skb,
struct flow_dissector_key_icmp *key_icmp,
void *data, int thoff, int hlen)
{
struct icmphdr *ih, _ih;
ih = __skb_header_pointer(skb, thoff, sizeof(_ih), data, hlen, &_ih);
if (!ih)
return;
key_icmp->type = ih->type;
key_icmp->code = ih->code;
/* As we use 0 to signal that the Id field is not present,
* avoid confusion with packets without such field
*/
if (icmp_has_id(ih->type))
key_icmp->id = ih->un.echo.id ? : 1;
else
key_icmp->id = 0;
}
EXPORT_SYMBOL(skb_flow_get_icmp_tci);
/* If FLOW_DISSECTOR_KEY_ICMP is set, dissect an ICMP packet
* using skb_flow_get_icmp_tci().
*/
static void __skb_flow_dissect_icmp(const struct sk_buff *skb,
struct flow_dissector *flow_dissector,
void *target_container,
void *data, int thoff, int hlen)
{
struct flow_dissector_key_icmp *key_icmp;
if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ICMP))
return;
key_icmp = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_ICMP,
target_container);
skb_flow_get_icmp_tci(skb, key_icmp, data, thoff, hlen);
}
void skb_flow_dissect_meta(const struct sk_buff *skb,
struct flow_dissector *flow_dissector,
void *target_container)
{
struct flow_dissector_key_meta *meta;
if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_META))
return;
meta = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_META,
target_container);
meta->ingress_ifindex = skb->skb_iif;
}
EXPORT_SYMBOL(skb_flow_dissect_meta);
static void
skb_flow_dissect_set_enc_addr_type(enum flow_dissector_key_id type,
struct flow_dissector *flow_dissector,
void *target_container)
{
struct flow_dissector_key_control *ctrl;
if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_CONTROL))
return;
ctrl = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_CONTROL,
target_container);
ctrl->addr_type = type;
}
void
skb_flow_dissect_ct(const struct sk_buff *skb,
struct flow_dissector *flow_dissector,
void *target_container,
u16 *ctinfo_map,
size_t mapsize)
{
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
struct flow_dissector_key_ct *key;
enum ip_conntrack_info ctinfo;
struct nf_conn_labels *cl;
struct nf_conn *ct;
if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_CT))
return;
ct = nf_ct_get(skb, &ctinfo);
if (!ct)
return;
key = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_CT,
target_container);
if (ctinfo < mapsize)
key->ct_state = ctinfo_map[ctinfo];
#if IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES)
key->ct_zone = ct->zone.id;
#endif
#if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)
key->ct_mark = ct->mark;
#endif
cl = nf_ct_labels_find(ct);
if (cl)
memcpy(key->ct_labels, cl->bits, sizeof(key->ct_labels));
#endif /* CONFIG_NF_CONNTRACK */
}
EXPORT_SYMBOL(skb_flow_dissect_ct);
void
skb_flow_dissect_tunnel_info(const struct sk_buff *skb,
struct flow_dissector *flow_dissector,
void *target_container)
{
struct ip_tunnel_info *info;
struct ip_tunnel_key *key;
/* A quick check to see if there might be something to do. */
if (!dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_KEYID) &&
!dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS) &&
!dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_IPV6_ADDRS) &&
!dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_CONTROL) &&
!dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_PORTS) &&
!dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_IP) &&
!dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_OPTS))
return;
info = skb_tunnel_info(skb);
if (!info)
return;
key = &info->key;
switch (ip_tunnel_info_af(info)) {
case AF_INET:
skb_flow_dissect_set_enc_addr_type(FLOW_DISSECTOR_KEY_IPV4_ADDRS,
flow_dissector,
target_container);
if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS)) {
struct flow_dissector_key_ipv4_addrs *ipv4;
ipv4 = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS,
target_container);
ipv4->src = key->u.ipv4.src;
ipv4->dst = key->u.ipv4.dst;
}
break;
case AF_INET6:
skb_flow_dissect_set_enc_addr_type(FLOW_DISSECTOR_KEY_IPV6_ADDRS,
flow_dissector,
target_container);
if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_IPV6_ADDRS)) {
struct flow_dissector_key_ipv6_addrs *ipv6;
ipv6 = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_IPV6_ADDRS,
target_container);
ipv6->src = key->u.ipv6.src;
ipv6->dst = key->u.ipv6.dst;
}
break;
}
if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_KEYID)) {
struct flow_dissector_key_keyid *keyid;
keyid = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_KEYID,
target_container);
keyid->keyid = tunnel_id_to_key32(key->tun_id);
}
if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_PORTS)) {
struct flow_dissector_key_ports *tp;
tp = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_PORTS,
target_container);
tp->src = key->tp_src;
tp->dst = key->tp_dst;
}
if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_IP)) {
struct flow_dissector_key_ip *ip;
ip = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_IP,
target_container);
ip->tos = key->tos;
ip->ttl = key->ttl;
}
if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_OPTS)) {
struct flow_dissector_key_enc_opts *enc_opt;
enc_opt = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_ENC_OPTS,
target_container);
if (info->options_len) {
enc_opt->len = info->options_len;
ip_tunnel_info_opts_get(enc_opt->data, info);
enc_opt->dst_opt_type = info->key.tun_flags &
TUNNEL_OPTIONS_PRESENT;
}
}
}
EXPORT_SYMBOL(skb_flow_dissect_tunnel_info);
static enum flow_dissect_ret
__skb_flow_dissect_mpls(const struct sk_buff *skb,
struct flow_dissector *flow_dissector,
void *target_container, void *data, int nhoff, int hlen)
{
struct flow_dissector_key_keyid *key_keyid;
struct mpls_label *hdr, _hdr[2];
u32 entry, label;
if (!dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_MPLS_ENTROPY) &&
!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_MPLS))
return FLOW_DISSECT_RET_OUT_GOOD;
hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data,
hlen, &_hdr);
if (!hdr)
return FLOW_DISSECT_RET_OUT_BAD;
entry = ntohl(hdr[0].entry);
label = (entry & MPLS_LS_LABEL_MASK) >> MPLS_LS_LABEL_SHIFT;
if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_MPLS)) {
struct flow_dissector_key_mpls *key_mpls;
key_mpls = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_MPLS,
target_container);
key_mpls->mpls_label = label;
key_mpls->mpls_ttl = (entry & MPLS_LS_TTL_MASK)
>> MPLS_LS_TTL_SHIFT;
key_mpls->mpls_tc = (entry & MPLS_LS_TC_MASK)
>> MPLS_LS_TC_SHIFT;
key_mpls->mpls_bos = (entry & MPLS_LS_S_MASK)
>> MPLS_LS_S_SHIFT;
}
if (label == MPLS_LABEL_ENTROPY) {
key_keyid = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_MPLS_ENTROPY,
target_container);
key_keyid->keyid = hdr[1].entry & htonl(MPLS_LS_LABEL_MASK);
}
return FLOW_DISSECT_RET_OUT_GOOD;
}
static enum flow_dissect_ret
__skb_flow_dissect_arp(const struct sk_buff *skb,
struct flow_dissector *flow_dissector,
void *target_container, void *data, int nhoff, int hlen)
{
struct flow_dissector_key_arp *key_arp;
struct {
unsigned char ar_sha[ETH_ALEN];
unsigned char ar_sip[4];
unsigned char ar_tha[ETH_ALEN];
unsigned char ar_tip[4];
} *arp_eth, _arp_eth;
const struct arphdr *arp;
struct arphdr _arp;
if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ARP))
return FLOW_DISSECT_RET_OUT_GOOD;
arp = __skb_header_pointer(skb, nhoff, sizeof(_arp), data,
hlen, &_arp);
if (!arp)
return FLOW_DISSECT_RET_OUT_BAD;
if (arp->ar_hrd != htons(ARPHRD_ETHER) ||
arp->ar_pro != htons(ETH_P_IP) ||
arp->ar_hln != ETH_ALEN ||
arp->ar_pln != 4 ||
(arp->ar_op != htons(ARPOP_REPLY) &&
arp->ar_op != htons(ARPOP_REQUEST)))
return FLOW_DISSECT_RET_OUT_BAD;
arp_eth = __skb_header_pointer(skb, nhoff + sizeof(_arp),
sizeof(_arp_eth), data,
hlen, &_arp_eth);
if (!arp_eth)
return FLOW_DISSECT_RET_OUT_BAD;
key_arp = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_ARP,
target_container);
memcpy(&key_arp->sip, arp_eth->ar_sip, sizeof(key_arp->sip));
memcpy(&key_arp->tip, arp_eth->ar_tip, sizeof(key_arp->tip));
/* Only store the lower byte of the opcode;
* this covers ARPOP_REPLY and ARPOP_REQUEST.
*/
key_arp->op = ntohs(arp->ar_op) & 0xff;
ether_addr_copy(key_arp->sha, arp_eth->ar_sha);
ether_addr_copy(key_arp->tha, arp_eth->ar_tha);
return FLOW_DISSECT_RET_OUT_GOOD;
}
static enum flow_dissect_ret
__skb_flow_dissect_gre(const struct sk_buff *skb,
struct flow_dissector_key_control *key_control,
struct flow_dissector *flow_dissector,
void *target_container, void *data,
__be16 *p_proto, int *p_nhoff, int *p_hlen,
unsigned int flags)
{
struct flow_dissector_key_keyid *key_keyid;
struct gre_base_hdr *hdr, _hdr;
int offset = 0;
u16 gre_ver;
hdr = __skb_header_pointer(skb, *p_nhoff, sizeof(_hdr),
data, *p_hlen, &_hdr);
if (!hdr)
return FLOW_DISSECT_RET_OUT_BAD;
/* Only look inside GRE without routing */
if (hdr->flags & GRE_ROUTING)
return FLOW_DISSECT_RET_OUT_GOOD;
/* Only look inside GRE for version 0 and 1 */
gre_ver = ntohs(hdr->flags & GRE_VERSION);
if (gre_ver > 1)
return FLOW_DISSECT_RET_OUT_GOOD;
*p_proto = hdr->protocol;
if (gre_ver) {
/* Version1 must be PPTP, and check the flags */
if (!(*p_proto == GRE_PROTO_PPP && (hdr->flags & GRE_KEY)))
return FLOW_DISSECT_RET_OUT_GOOD;
}
offset += sizeof(struct gre_base_hdr);
if (hdr->flags & GRE_CSUM)
offset += sizeof_field(struct gre_full_hdr, csum) +
sizeof_field(struct gre_full_hdr, reserved1);
if (hdr->flags & GRE_KEY) {
const __be32 *keyid;
__be32 _keyid;
keyid = __skb_header_pointer(skb, *p_nhoff + offset,
sizeof(_keyid),
data, *p_hlen, &_keyid);
if (!keyid)
return FLOW_DISSECT_RET_OUT_BAD;
if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_GRE_KEYID)) {
key_keyid = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_GRE_KEYID,
target_container);
if (gre_ver == 0)
key_keyid->keyid = *keyid;
else
key_keyid->keyid = *keyid & GRE_PPTP_KEY_MASK;
}
offset += sizeof_field(struct gre_full_hdr, key);
}
if (hdr->flags & GRE_SEQ)
offset += sizeof_field(struct pptp_gre_header, seq);
if (gre_ver == 0) {
if (*p_proto == htons(ETH_P_TEB)) {
const struct ethhdr *eth;
struct ethhdr _eth;
eth = __skb_header_pointer(skb, *p_nhoff + offset,
sizeof(_eth),
data, *p_hlen, &_eth);
if (!eth)
return FLOW_DISSECT_RET_OUT_BAD;
*p_proto = eth->h_proto;
offset += sizeof(*eth);
/* Cap headers that we access via pointers at the
* end of the Ethernet header as our maximum alignment
* at that point is only 2 bytes.
*/
if (NET_IP_ALIGN)
*p_hlen = *p_nhoff + offset;
}
} else { /* version 1, must be PPTP */
u8 _ppp_hdr[PPP_HDRLEN];
u8 *ppp_hdr;
if (hdr->flags & GRE_ACK)
offset += sizeof_field(struct pptp_gre_header, ack);
ppp_hdr = __skb_header_pointer(skb, *p_nhoff + offset,
sizeof(_ppp_hdr),
data, *p_hlen, _ppp_hdr);
if (!ppp_hdr)
return FLOW_DISSECT_RET_OUT_BAD;
switch (PPP_PROTOCOL(ppp_hdr)) {
case PPP_IP:
*p_proto = htons(ETH_P_IP);
break;
case PPP_IPV6:
*p_proto = htons(ETH_P_IPV6);
break;
default:
/* Could probably catch some more like MPLS */
break;
}
offset += PPP_HDRLEN;
}
*p_nhoff += offset;
key_control->flags |= FLOW_DIS_ENCAPSULATION;
if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP)
return FLOW_DISSECT_RET_OUT_GOOD;
return FLOW_DISSECT_RET_PROTO_AGAIN;
}
/**
* __skb_flow_dissect_batadv() - dissect batman-adv header
* @skb: sk_buff to with the batman-adv header
* @key_control: flow dissectors control key
* @data: raw buffer pointer to the packet, if NULL use skb->data
* @p_proto: pointer used to update the protocol to process next
* @p_nhoff: pointer used to update inner network header offset
* @hlen: packet header length
* @flags: any combination of FLOW_DISSECTOR_F_*
*
* ETH_P_BATMAN packets are tried to be dissected. Only
* &struct batadv_unicast packets are actually processed because they contain an
* inner ethernet header and are usually followed by actual network header. This
* allows the flow dissector to continue processing the packet.
*
* Return: FLOW_DISSECT_RET_PROTO_AGAIN when &struct batadv_unicast was found,
* FLOW_DISSECT_RET_OUT_GOOD when dissector should stop after encapsulation,
* otherwise FLOW_DISSECT_RET_OUT_BAD
*/
static enum flow_dissect_ret
__skb_flow_dissect_batadv(const struct sk_buff *skb,
struct flow_dissector_key_control *key_control,
void *data, __be16 *p_proto, int *p_nhoff, int hlen,
unsigned int flags)
{
struct {
struct batadv_unicast_packet batadv_unicast;
struct ethhdr eth;
} *hdr, _hdr;
hdr = __skb_header_pointer(skb, *p_nhoff, sizeof(_hdr), data, hlen,
&_hdr);
if (!hdr)
return FLOW_DISSECT_RET_OUT_BAD;
if (hdr->batadv_unicast.version != BATADV_COMPAT_VERSION)
return FLOW_DISSECT_RET_OUT_BAD;
if (hdr->batadv_unicast.packet_type != BATADV_UNICAST)
return FLOW_DISSECT_RET_OUT_BAD;
*p_proto = hdr->eth.h_proto;
*p_nhoff += sizeof(*hdr);
key_control->flags |= FLOW_DIS_ENCAPSULATION;
if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP)
return FLOW_DISSECT_RET_OUT_GOOD;
return FLOW_DISSECT_RET_PROTO_AGAIN;
}
static void
__skb_flow_dissect_tcp(const struct sk_buff *skb,
struct flow_dissector *flow_dissector,
void *target_container, void *data, int thoff, int hlen)
{
struct flow_dissector_key_tcp *key_tcp;
struct tcphdr *th, _th;
if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_TCP))
return;
th = __skb_header_pointer(skb, thoff, sizeof(_th), data, hlen, &_th);
if (!th)
return;
if (unlikely(__tcp_hdrlen(th) < sizeof(_th)))
return;
key_tcp = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_TCP,
target_container);
key_tcp->flags = (*(__be16 *) &tcp_flag_word(th) & htons(0x0FFF));
}
static void
__skb_flow_dissect_ports(const struct sk_buff *skb,
struct flow_dissector *flow_dissector,
void *target_container, void *data, int nhoff,
u8 ip_proto, int hlen)
{
enum flow_dissector_key_id dissector_ports = FLOW_DISSECTOR_KEY_MAX;
struct flow_dissector_key_ports *key_ports;
if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_PORTS))
dissector_ports = FLOW_DISSECTOR_KEY_PORTS;
else if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_PORTS_RANGE))
dissector_ports = FLOW_DISSECTOR_KEY_PORTS_RANGE;
if (dissector_ports == FLOW_DISSECTOR_KEY_MAX)
return;
key_ports = skb_flow_dissector_target(flow_dissector,
dissector_ports,
target_container);
key_ports->ports = __skb_flow_get_ports(skb, nhoff, ip_proto,
data, hlen);
}
static void
__skb_flow_dissect_ipv4(const struct sk_buff *skb,
struct flow_dissector *flow_dissector,
void *target_container, void *data, const struct iphdr *iph)
{
struct flow_dissector_key_ip *key_ip;
if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_IP))
return;
key_ip = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_IP,
target_container);
key_ip->tos = iph->tos;
key_ip->ttl = iph->ttl;
}
static void
__skb_flow_dissect_ipv6(const struct sk_buff *skb,
struct flow_dissector *flow_dissector,
void *target_container, void *data, const struct ipv6hdr *iph)
{
struct flow_dissector_key_ip *key_ip;
if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_IP))
return;
key_ip = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_IP,
target_container);
key_ip->tos = ipv6_get_dsfield(iph);
key_ip->ttl = iph->hop_limit;
}
/* Maximum number of protocol headers that can be parsed in
* __skb_flow_dissect
*/
#define MAX_FLOW_DISSECT_HDRS 15
static bool skb_flow_dissect_allowed(int *num_hdrs)
{
++*num_hdrs;
return (*num_hdrs <= MAX_FLOW_DISSECT_HDRS);
}
static void __skb_flow_bpf_to_target(const struct bpf_flow_keys *flow_keys,
struct flow_dissector *flow_dissector,
void *target_container)
{
struct flow_dissector_key_ports *key_ports = NULL;
struct flow_dissector_key_control *key_control;
struct flow_dissector_key_basic *key_basic;
struct flow_dissector_key_addrs *key_addrs;
struct flow_dissector_key_tags *key_tags;
key_control = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_CONTROL,
target_container);
key_control->thoff = flow_keys->thoff;
if (flow_keys->is_frag)
key_control->flags |= FLOW_DIS_IS_FRAGMENT;
if (flow_keys->is_first_frag)
key_control->flags |= FLOW_DIS_FIRST_FRAG;
if (flow_keys->is_encap)
key_control->flags |= FLOW_DIS_ENCAPSULATION;
key_basic = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_BASIC,
target_container);
key_basic->n_proto = flow_keys->n_proto;
key_basic->ip_proto = flow_keys->ip_proto;
if (flow_keys->addr_proto == ETH_P_IP &&
dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_IPV4_ADDRS)) {
key_addrs = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_IPV4_ADDRS,
target_container);
key_addrs->v4addrs.src = flow_keys->ipv4_src;
key_addrs->v4addrs.dst = flow_keys->ipv4_dst;
key_control->addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
} else if (flow_keys->addr_proto == ETH_P_IPV6 &&
dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_IPV6_ADDRS)) {
key_addrs = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_IPV6_ADDRS,
target_container);
memcpy(&key_addrs->v6addrs, &flow_keys->ipv6_src,
sizeof(key_addrs->v6addrs));
key_control->addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
}
if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_PORTS))
key_ports = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_PORTS,
target_container);
else if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_PORTS_RANGE))
key_ports = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_PORTS_RANGE,
target_container);
if (key_ports) {
key_ports->src = flow_keys->sport;
key_ports->dst = flow_keys->dport;
}
if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_FLOW_LABEL)) {
key_tags = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_FLOW_LABEL,
target_container);
key_tags->flow_label = ntohl(flow_keys->flow_label);
}
}
bool bpf_flow_dissect(struct bpf_prog *prog, struct bpf_flow_dissector *ctx,
__be16 proto, int nhoff, int hlen, unsigned int flags)
{
struct bpf_flow_keys *flow_keys = ctx->flow_keys;
u32 result;
/* Pass parameters to the BPF program */
memset(flow_keys, 0, sizeof(*flow_keys));
flow_keys->n_proto = proto;
flow_keys->nhoff = nhoff;
flow_keys->thoff = flow_keys->nhoff;
BUILD_BUG_ON((int)BPF_FLOW_DISSECTOR_F_PARSE_1ST_FRAG !=
(int)FLOW_DISSECTOR_F_PARSE_1ST_FRAG);
BUILD_BUG_ON((int)BPF_FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL !=
(int)FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL);
BUILD_BUG_ON((int)BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP !=
(int)FLOW_DISSECTOR_F_STOP_AT_ENCAP);
flow_keys->flags = flags;
result = bpf_prog_run_pin_on_cpu(prog, ctx);
flow_keys->nhoff = clamp_t(u16, flow_keys->nhoff, nhoff, hlen);
flow_keys->thoff = clamp_t(u16, flow_keys->thoff,
flow_keys->nhoff, hlen);
return result == BPF_OK;
}
/**
* __skb_flow_dissect - extract the flow_keys struct and return it
* @net: associated network namespace, derived from @skb if NULL
* @skb: sk_buff to extract the flow from, can be NULL if the rest are specified
* @flow_dissector: list of keys to dissect
* @target_container: target structure to put dissected values into
* @data: raw buffer pointer to the packet, if NULL use skb->data
* @proto: protocol for which to get the flow, if @data is NULL use skb->protocol
* @nhoff: network header offset, if @data is NULL use skb_network_offset(skb)
* @hlen: packet header length, if @data is NULL use skb_headlen(skb)
* @flags: flags that control the dissection process, e.g.
* FLOW_DISSECTOR_F_STOP_AT_ENCAP.
*
* The function will try to retrieve individual keys into target specified
* by flow_dissector from either the skbuff or a raw buffer specified by the
* rest parameters.
*
* Caller must take care of zeroing target container memory.
*/
bool __skb_flow_dissect(const struct net *net,
const struct sk_buff *skb,
struct flow_dissector *flow_dissector,
void *target_container,
void *data, __be16 proto, int nhoff, int hlen,
unsigned int flags)
{
struct flow_dissector_key_control *key_control;
struct flow_dissector_key_basic *key_basic;
struct flow_dissector_key_addrs *key_addrs;
struct flow_dissector_key_tags *key_tags;
struct flow_dissector_key_vlan *key_vlan;
struct bpf_prog *attached = NULL;
enum flow_dissect_ret fdret;
enum flow_dissector_key_id dissector_vlan = FLOW_DISSECTOR_KEY_MAX;
int num_hdrs = 0;
u8 ip_proto = 0;
bool ret;
if (!data) {
data = skb->data;
proto = skb_vlan_tag_present(skb) ?
skb->vlan_proto : skb->protocol;
nhoff = skb_network_offset(skb);
hlen = skb_headlen(skb);
#if IS_ENABLED(CONFIG_NET_DSA)
if (unlikely(skb->dev && netdev_uses_dsa(skb->dev) &&
proto == htons(ETH_P_XDSA))) {
const struct dsa_device_ops *ops;
int offset = 0;
ops = skb->dev->dsa_ptr->tag_ops;
if (ops->flow_dissect &&
!ops->flow_dissect(skb, &proto, &offset)) {
hlen -= offset;
nhoff += offset;
}
}
#endif
}
/* It is ensured by skb_flow_dissector_init() that control key will
* be always present.
*/
key_control = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_CONTROL,
target_container);
/* It is ensured by skb_flow_dissector_init() that basic key will
* be always present.
*/
key_basic = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_BASIC,
target_container);
if (skb) {
if (!net) {
if (skb->dev)
net = dev_net(skb->dev);
else if (skb->sk)
net = sock_net(skb->sk);
}
}
WARN_ON_ONCE(!net);
if (net) {
rcu_read_lock();
attached = rcu_dereference(init_net.flow_dissector_prog);
if (!attached)
attached = rcu_dereference(net->flow_dissector_prog);
if (attached) {
struct bpf_flow_keys flow_keys;
struct bpf_flow_dissector ctx = {
.flow_keys = &flow_keys,
.data = data,
.data_end = data + hlen,
};
__be16 n_proto = proto;
if (skb) {
ctx.skb = skb;
/* we can't use 'proto' in the skb case
* because it might be set to skb->vlan_proto
* which has been pulled from the data
*/
n_proto = skb->protocol;
}
ret = bpf_flow_dissect(attached, &ctx, n_proto, nhoff,
hlen, flags);
__skb_flow_bpf_to_target(&flow_keys, flow_dissector,
target_container);
rcu_read_unlock();
return ret;
}
rcu_read_unlock();
}
if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_ETH_ADDRS)) {
struct ethhdr *eth = eth_hdr(skb);
struct flow_dissector_key_eth_addrs *key_eth_addrs;
key_eth_addrs = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_ETH_ADDRS,
target_container);
memcpy(key_eth_addrs, &eth->h_dest, sizeof(*key_eth_addrs));
}
proto_again:
fdret = FLOW_DISSECT_RET_CONTINUE;
switch (proto) {
case htons(ETH_P_IP): {
const struct iphdr *iph;
struct iphdr _iph;
iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph);
if (!iph || iph->ihl < 5) {
fdret = FLOW_DISSECT_RET_OUT_BAD;
break;
}
nhoff += iph->ihl * 4;
ip_proto = iph->protocol;
if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_IPV4_ADDRS)) {
key_addrs = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_IPV4_ADDRS,
target_container);
memcpy(&key_addrs->v4addrs, &iph->saddr,
sizeof(key_addrs->v4addrs));
key_control->addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
}
if (ip_is_fragment(iph)) {
key_control->flags |= FLOW_DIS_IS_FRAGMENT;
if (iph->frag_off & htons(IP_OFFSET)) {
fdret = FLOW_DISSECT_RET_OUT_GOOD;
break;
} else {
key_control->flags |= FLOW_DIS_FIRST_FRAG;
if (!(flags &
FLOW_DISSECTOR_F_PARSE_1ST_FRAG)) {
fdret = FLOW_DISSECT_RET_OUT_GOOD;
break;
}
}
}
__skb_flow_dissect_ipv4(skb, flow_dissector,
target_container, data, iph);
break;
}
case htons(ETH_P_IPV6): {
const struct ipv6hdr *iph;
struct ipv6hdr _iph;
iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph);
if (!iph) {
fdret = FLOW_DISSECT_RET_OUT_BAD;
break;
}
ip_proto = iph->nexthdr;
nhoff += sizeof(struct ipv6hdr);
if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_IPV6_ADDRS)) {
key_addrs = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_IPV6_ADDRS,
target_container);
memcpy(&key_addrs->v6addrs, &iph->saddr,
sizeof(key_addrs->v6addrs));
key_control->addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
}
if ((dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_FLOW_LABEL) ||
(flags & FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL)) &&
ip6_flowlabel(iph)) {
__be32 flow_label = ip6_flowlabel(iph);
if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_FLOW_LABEL)) {
key_tags = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_FLOW_LABEL,
target_container);
key_tags->flow_label = ntohl(flow_label);
}
if (flags & FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL) {
fdret = FLOW_DISSECT_RET_OUT_GOOD;
break;
}
}
__skb_flow_dissect_ipv6(skb, flow_dissector,
target_container, data, iph);
break;
}
case htons(ETH_P_8021AD):
case htons(ETH_P_8021Q): {
const struct vlan_hdr *vlan = NULL;
struct vlan_hdr _vlan;
__be16 saved_vlan_tpid = proto;
if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX &&
skb && skb_vlan_tag_present(skb)) {
proto = skb->protocol;
} else {
vlan = __skb_header_pointer(skb, nhoff, sizeof(_vlan),
data, hlen, &_vlan);
if (!vlan) {
fdret = FLOW_DISSECT_RET_OUT_BAD;
break;
}
proto = vlan->h_vlan_encapsulated_proto;
nhoff += sizeof(*vlan);
}
if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX) {
dissector_vlan = FLOW_DISSECTOR_KEY_VLAN;
} else if (dissector_vlan == FLOW_DISSECTOR_KEY_VLAN) {
dissector_vlan = FLOW_DISSECTOR_KEY_CVLAN;
} else {
fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
break;
}
if (dissector_uses_key(flow_dissector, dissector_vlan)) {
key_vlan = skb_flow_dissector_target(flow_dissector,
dissector_vlan,
target_container);
if (!vlan) {
key_vlan->vlan_id = skb_vlan_tag_get_id(skb);
key_vlan->vlan_priority = skb_vlan_tag_get_prio(skb);
} else {
key_vlan->vlan_id = ntohs(vlan->h_vlan_TCI) &
VLAN_VID_MASK;
key_vlan->vlan_priority =
(ntohs(vlan->h_vlan_TCI) &
VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
}
key_vlan->vlan_tpid = saved_vlan_tpid;
}
fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
break;
}
case htons(ETH_P_PPP_SES): {
struct {
struct pppoe_hdr hdr;
__be16 proto;
} *hdr, _hdr;
hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr);
if (!hdr) {
fdret = FLOW_DISSECT_RET_OUT_BAD;
break;
}
proto = hdr->proto;
nhoff += PPPOE_SES_HLEN;
switch (proto) {
case htons(PPP_IP):
proto = htons(ETH_P_IP);
fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
break;
case htons(PPP_IPV6):
proto = htons(ETH_P_IPV6);
fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
break;
default:
fdret = FLOW_DISSECT_RET_OUT_BAD;
break;
}
break;
}
case htons(ETH_P_TIPC): {
struct tipc_basic_hdr *hdr, _hdr;
hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr),
data, hlen, &_hdr);
if (!hdr) {
fdret = FLOW_DISSECT_RET_OUT_BAD;
break;
}
if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_TIPC)) {
key_addrs = skb_flow_dissector_target(flow_dissector,
FLOW_DISSECTOR_KEY_TIPC,
target_container);
key_addrs->tipckey.key = tipc_hdr_rps_key(hdr);
key_control->addr_type = FLOW_DISSECTOR_KEY_TIPC;
}
fdret = FLOW_DISSECT_RET_OUT_GOOD;
break;
}
case htons(ETH_P_MPLS_UC):
case htons(ETH_P_MPLS_MC):
fdret = __skb_flow_dissect_mpls(skb, flow_dissector,
target_container, data,
nhoff, hlen);
break;
case htons(ETH_P_FCOE):
if ((hlen - nhoff) < FCOE_HEADER_LEN) {
fdret = FLOW_DISSECT_RET_OUT_BAD;
break;
}
nhoff += FCOE_HEADER_LEN;
fdret = FLOW_DISSECT_RET_OUT_GOOD;
break;
case htons(ETH_P_ARP):
case htons(ETH_P_RARP):
fdret = __skb_flow_dissect_arp(skb, flow_dissector,
target_container, data,
nhoff, hlen);
break;
case htons(ETH_P_BATMAN):
fdret = __skb_flow_dissect_batadv(skb, key_control, data,
&proto, &nhoff, hlen, flags);
break;
default:
fdret = FLOW_DISSECT_RET_OUT_BAD;
break;
}
/* Process result of proto processing */
switch (fdret) {
case FLOW_DISSECT_RET_OUT_GOOD:
goto out_good;
case FLOW_DISSECT_RET_PROTO_AGAIN:
if (skb_flow_dissect_allowed(&num_hdrs))
goto proto_again;
goto out_good;
case FLOW_DISSECT_RET_CONTINUE:
case FLOW_DISSECT_RET_IPPROTO_AGAIN:
break;
case FLOW_DISSECT_RET_OUT_BAD:
default:
goto out_bad;
}
ip_proto_again:
fdret = FLOW_DISSECT_RET_CONTINUE;
switch (ip_proto) {
case IPPROTO_GRE:
fdret = __skb_flow_dissect_gre(skb, key_control, flow_dissector,
target_container, data,
&proto, &nhoff, &hlen, flags);
break;
case NEXTHDR_HOP:
case NEXTHDR_ROUTING:
case NEXTHDR_DEST: {
u8 _opthdr[2], *opthdr;
if (proto != htons(ETH_P_IPV6))
break;
opthdr = __skb_header_pointer(skb, nhoff, sizeof(_opthdr),
data, hlen, &_opthdr);
if (!opthdr) {
fdret = FLOW_DISSECT_RET_OUT_BAD;
break;
}
ip_proto = opthdr[0];
nhoff += (opthdr[1] + 1) << 3;
fdret = FLOW_DISSECT_RET_IPPROTO_AGAIN;
break;
}
case NEXTHDR_FRAGMENT: {
struct frag_hdr _fh, *fh;
if (proto != htons(ETH_P_IPV6))
break;
fh = __skb_header_pointer(skb, nhoff, sizeof(_fh),
data, hlen, &_fh);
if (!fh) {
fdret = FLOW_DISSECT_RET_OUT_BAD;
break;
}
key_control->flags |= FLOW_DIS_IS_FRAGMENT;
nhoff += sizeof(_fh);
ip_proto = fh->nexthdr;
if (!(fh->frag_off & htons(IP6_OFFSET))) {
key_control->flags |= FLOW_DIS_FIRST_FRAG;
if (flags & FLOW_DISSECTOR_F_PARSE_1ST_FRAG) {
fdret = FLOW_DISSECT_RET_IPPROTO_AGAIN;
break;
}
}
fdret = FLOW_DISSECT_RET_OUT_GOOD;
break;
}
case IPPROTO_IPIP:
proto = htons(ETH_P_IP);
key_control->flags |= FLOW_DIS_ENCAPSULATION;
if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP) {
fdret = FLOW_DISSECT_RET_OUT_GOOD;
break;
}
fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
break;
case IPPROTO_IPV6:
proto = htons(ETH_P_IPV6);
key_control->flags |= FLOW_DIS_ENCAPSULATION;
if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP) {
fdret = FLOW_DISSECT_RET_OUT_GOOD;
break;
}
fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
break;
case IPPROTO_MPLS:
proto = htons(ETH_P_MPLS_UC);
fdret = FLOW_DISSECT_RET_PROTO_AGAIN;
break;
case IPPROTO_TCP:
__skb_flow_dissect_tcp(skb, flow_dissector, target_container,
data, nhoff, hlen);
break;
case IPPROTO_ICMP:
case IPPROTO_ICMPV6:
__skb_flow_dissect_icmp(skb, flow_dissector, target_container,
data, nhoff, hlen);
break;
default:
break;
}
if (!(key_control->flags & FLOW_DIS_IS_FRAGMENT))
__skb_flow_dissect_ports(skb, flow_dissector, target_container,
data, nhoff, ip_proto, hlen);
/* Process result of IP proto processing */
switch (fdret) {
case FLOW_DISSECT_RET_PROTO_AGAIN:
if (skb_flow_dissect_allowed(&num_hdrs))
goto proto_again;
break;
case FLOW_DISSECT_RET_IPPROTO_AGAIN:
if (skb_flow_dissect_allowed(&num_hdrs))
goto ip_proto_again;
break;
case FLOW_DISSECT_RET_OUT_GOOD:
case FLOW_DISSECT_RET_CONTINUE:
break;
case FLOW_DISSECT_RET_OUT_BAD:
default:
goto out_bad;
}
out_good:
ret = true;
out:
key_control->thoff = min_t(u16, nhoff, skb ? skb->len : hlen);
key_basic->n_proto = proto;
key_basic->ip_proto = ip_proto;
return ret;
out_bad:
ret = false;
goto out;
}
EXPORT_SYMBOL(__skb_flow_dissect);
static siphash_key_t hashrnd __read_mostly;
static __always_inline void __flow_hash_secret_init(void)
{
net_get_random_once(&hashrnd, sizeof(hashrnd));
}
static const void *flow_keys_hash_start(const struct flow_keys *flow)
{
BUILD_BUG_ON(FLOW_KEYS_HASH_OFFSET % SIPHASH_ALIGNMENT);
return &flow->FLOW_KEYS_HASH_START_FIELD;
}
static inline size_t flow_keys_hash_length(const struct flow_keys *flow)
{
size_t diff = FLOW_KEYS_HASH_OFFSET + sizeof(flow->addrs);
BUILD_BUG_ON((sizeof(*flow) - FLOW_KEYS_HASH_OFFSET) % sizeof(u32));
switch (flow->control.addr_type) {
case FLOW_DISSECTOR_KEY_IPV4_ADDRS:
diff -= sizeof(flow->addrs.v4addrs);
break;
case FLOW_DISSECTOR_KEY_IPV6_ADDRS:
diff -= sizeof(flow->addrs.v6addrs);
break;
case FLOW_DISSECTOR_KEY_TIPC:
diff -= sizeof(flow->addrs.tipckey);
break;
}
return sizeof(*flow) - diff;
}
__be32 flow_get_u32_src(const struct flow_keys *flow)
{
switch (flow->control.addr_type) {
case FLOW_DISSECTOR_KEY_IPV4_ADDRS:
return flow->addrs.v4addrs.src;
case FLOW_DISSECTOR_KEY_IPV6_ADDRS:
return (__force __be32)ipv6_addr_hash(
&flow->addrs.v6addrs.src);
case FLOW_DISSECTOR_KEY_TIPC:
return flow->addrs.tipckey.key;
default:
return 0;
}
}
EXPORT_SYMBOL(flow_get_u32_src);
__be32 flow_get_u32_dst(const struct flow_keys *flow)
{
switch (flow->control.addr_type) {
case FLOW_DISSECTOR_KEY_IPV4_ADDRS:
return flow->addrs.v4addrs.dst;
case FLOW_DISSECTOR_KEY_IPV6_ADDRS:
return (__force __be32)ipv6_addr_hash(
&flow->addrs.v6addrs.dst);
default:
return 0;
}
}
EXPORT_SYMBOL(flow_get_u32_dst);
/* Sort the source and destination IP (and the ports if the IP are the same),
* to have consistent hash within the two directions
*/
static inline void __flow_hash_consistentify(struct flow_keys *keys)
{
int addr_diff, i;
switch (keys->control.addr_type) {
case FLOW_DISSECTOR_KEY_IPV4_ADDRS:
addr_diff = (__force u32)keys->addrs.v4addrs.dst -
(__force u32)keys->addrs.v4addrs.src;
if ((addr_diff < 0) ||
(addr_diff == 0 &&
((__force u16)keys->ports.dst <
(__force u16)keys->ports.src))) {
swap(keys->addrs.v4addrs.src, keys->addrs.v4addrs.dst);
swap(keys->ports.src, keys->ports.dst);
}
break;
case FLOW_DISSECTOR_KEY_IPV6_ADDRS:
addr_diff = memcmp(&keys->addrs.v6addrs.dst,
&keys->addrs.v6addrs.src,
sizeof(keys->addrs.v6addrs.dst));
if ((addr_diff < 0) ||
(addr_diff == 0 &&
((__force u16)keys->ports.dst <
(__force u16)keys->ports.src))) {
for (i = 0; i < 4; i++)
swap(keys->addrs.v6addrs.src.s6_addr32[i],
keys->addrs.v6addrs.dst.s6_addr32[i]);
swap(keys->ports.src, keys->ports.dst);
}
break;
}
}
static inline u32 __flow_hash_from_keys(struct flow_keys *keys,
const siphash_key_t *keyval)
{
u32 hash;
__flow_hash_consistentify(keys);
hash = siphash(flow_keys_hash_start(keys),
flow_keys_hash_length(keys), keyval);
if (!hash)
hash = 1;
return hash;
}
u32 flow_hash_from_keys(struct flow_keys *keys)
{
__flow_hash_secret_init();
return __flow_hash_from_keys(keys, &hashrnd);
}
EXPORT_SYMBOL(flow_hash_from_keys);
static inline u32 ___skb_get_hash(const struct sk_buff *skb,
struct flow_keys *keys,
const siphash_key_t *keyval)
{
skb_flow_dissect_flow_keys(skb, keys,
FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL);
return __flow_hash_from_keys(keys, keyval);
}
struct _flow_keys_digest_data {
__be16 n_proto;
u8 ip_proto;
u8 padding;
__be32 ports;
__be32 src;
__be32 dst;
};
void make_flow_keys_digest(struct flow_keys_digest *digest,
const struct flow_keys *flow)
{
struct _flow_keys_digest_data *data =
(struct _flow_keys_digest_data *)digest;
BUILD_BUG_ON(sizeof(*data) > sizeof(*digest));
memset(digest, 0, sizeof(*digest));
data->n_proto = flow->basic.n_proto;
data->ip_proto = flow->basic.ip_proto;
data->ports = flow->ports.ports;
data->src = flow->addrs.v4addrs.src;
data->dst = flow->addrs.v4addrs.dst;
}
EXPORT_SYMBOL(make_flow_keys_digest);
static struct flow_dissector flow_keys_dissector_symmetric __read_mostly;
u32 __skb_get_hash_symmetric(const struct sk_buff *skb)
{
struct flow_keys keys;
__flow_hash_secret_init();
memset(&keys, 0, sizeof(keys));
__skb_flow_dissect(NULL, skb, &flow_keys_dissector_symmetric,
&keys, NULL, 0, 0, 0,
FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL);
return __flow_hash_from_keys(&keys, &hashrnd);
}
EXPORT_SYMBOL_GPL(__skb_get_hash_symmetric);
/**
* __skb_get_hash: calculate a flow hash
* @skb: sk_buff to calculate flow hash from
*
* This function calculates a flow hash based on src/dst addresses
* and src/dst port numbers. Sets hash in skb to non-zero hash value
* on success, zero indicates no valid hash. Also, sets l4_hash in skb
* if hash is a canonical 4-tuple hash over transport ports.
*/
void __skb_get_hash(struct sk_buff *skb)
{
struct flow_keys keys;
u32 hash;
__flow_hash_secret_init();
hash = ___skb_get_hash(skb, &keys, &hashrnd);
__skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys));
}
EXPORT_SYMBOL(__skb_get_hash);
__u32 skb_get_hash_perturb(const struct sk_buff *skb,
const siphash_key_t *perturb)
{
struct flow_keys keys;
return ___skb_get_hash(skb, &keys, perturb);
}
EXPORT_SYMBOL(skb_get_hash_perturb);
u32 __skb_get_poff(const struct sk_buff *skb, void *data,
const struct flow_keys_basic *keys, int hlen)
{
u32 poff = keys->control.thoff;
/* skip L4 headers for fragments after the first */
if ((keys->control.flags & FLOW_DIS_IS_FRAGMENT) &&
!(keys->control.flags & FLOW_DIS_FIRST_FRAG))
return poff;
switch (keys->basic.ip_proto) {
case IPPROTO_TCP: {
/* access doff as u8 to avoid unaligned access */
const u8 *doff;
u8 _doff;
doff = __skb_header_pointer(skb, poff + 12, sizeof(_doff),
data, hlen, &_doff);
if (!doff)
return poff;
poff += max_t(u32, sizeof(struct tcphdr), (*doff & 0xF0) >> 2);
break;
}
case IPPROTO_UDP:
case IPPROTO_UDPLITE:
poff += sizeof(struct udphdr);
break;
/* For the rest, we do not really care about header
* extensions at this point for now.
*/
case IPPROTO_ICMP:
poff += sizeof(struct icmphdr);
break;
case IPPROTO_ICMPV6:
poff += sizeof(struct icmp6hdr);
break;
case IPPROTO_IGMP:
poff += sizeof(struct igmphdr);
break;
case IPPROTO_DCCP:
poff += sizeof(struct dccp_hdr);
break;
case IPPROTO_SCTP:
poff += sizeof(struct sctphdr);
break;
}
return poff;
}
/**
* skb_get_poff - get the offset to the payload
* @skb: sk_buff to get the payload offset from
*
* The function will get the offset to the payload as far as it could
* be dissected. The main user is currently BPF, so that we can dynamically
* truncate packets without needing to push actual payload to the user
* space and can analyze headers only, instead.
*/
u32 skb_get_poff(const struct sk_buff *skb)
{
struct flow_keys_basic keys;
if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys,
NULL, 0, 0, 0, 0))
return 0;
return __skb_get_poff(skb, skb->data, &keys, skb_headlen(skb));
}
__u32 __get_hash_from_flowi6(const struct flowi6 *fl6, struct flow_keys *keys)
{
memset(keys, 0, sizeof(*keys));
memcpy(&keys->addrs.v6addrs.src, &fl6->saddr,
sizeof(keys->addrs.v6addrs.src));
memcpy(&keys->addrs.v6addrs.dst, &fl6->daddr,
sizeof(keys->addrs.v6addrs.dst));
keys->control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
keys->ports.src = fl6->fl6_sport;
keys->ports.dst = fl6->fl6_dport;
keys->keyid.keyid = fl6->fl6_gre_key;
keys->tags.flow_label = (__force u32)flowi6_get_flowlabel(fl6);
keys->basic.ip_proto = fl6->flowi6_proto;
return flow_hash_from_keys(keys);
}
EXPORT_SYMBOL(__get_hash_from_flowi6);
static const struct flow_dissector_key flow_keys_dissector_keys[] = {
{
.key_id = FLOW_DISSECTOR_KEY_CONTROL,
.offset = offsetof(struct flow_keys, control),
},
{
.key_id = FLOW_DISSECTOR_KEY_BASIC,
.offset = offsetof(struct flow_keys, basic),
},
{
.key_id = FLOW_DISSECTOR_KEY_IPV4_ADDRS,
.offset = offsetof(struct flow_keys, addrs.v4addrs),
},
{
.key_id = FLOW_DISSECTOR_KEY_IPV6_ADDRS,
.offset = offsetof(struct flow_keys, addrs.v6addrs),
},
{
.key_id = FLOW_DISSECTOR_KEY_TIPC,
.offset = offsetof(struct flow_keys, addrs.tipckey),
},
{
.key_id = FLOW_DISSECTOR_KEY_PORTS,
.offset = offsetof(struct flow_keys, ports),
},
{
.key_id = FLOW_DISSECTOR_KEY_VLAN,
.offset = offsetof(struct flow_keys, vlan),
},
{
.key_id = FLOW_DISSECTOR_KEY_FLOW_LABEL,
.offset = offsetof(struct flow_keys, tags),
},
{
.key_id = FLOW_DISSECTOR_KEY_GRE_KEYID,
.offset = offsetof(struct flow_keys, keyid),
},
};
static const struct flow_dissector_key flow_keys_dissector_symmetric_keys[] = {
{
.key_id = FLOW_DISSECTOR_KEY_CONTROL,
.offset = offsetof(struct flow_keys, control),
},
{
.key_id = FLOW_DISSECTOR_KEY_BASIC,
.offset = offsetof(struct flow_keys, basic),
},
{
.key_id = FLOW_DISSECTOR_KEY_IPV4_ADDRS,
.offset = offsetof(struct flow_keys, addrs.v4addrs),
},
{
.key_id = FLOW_DISSECTOR_KEY_IPV6_ADDRS,
.offset = offsetof(struct flow_keys, addrs.v6addrs),
},
{
.key_id = FLOW_DISSECTOR_KEY_PORTS,
.offset = offsetof(struct flow_keys, ports),
},
};
static const struct flow_dissector_key flow_keys_basic_dissector_keys[] = {
{
.key_id = FLOW_DISSECTOR_KEY_CONTROL,
.offset = offsetof(struct flow_keys, control),
},
{
.key_id = FLOW_DISSECTOR_KEY_BASIC,
.offset = offsetof(struct flow_keys, basic),
},
};
struct flow_dissector flow_keys_dissector __read_mostly;
EXPORT_SYMBOL(flow_keys_dissector);
struct flow_dissector flow_keys_basic_dissector __read_mostly;
EXPORT_SYMBOL(flow_keys_basic_dissector);
static int __init init_default_flow_dissectors(void)
{
skb_flow_dissector_init(&flow_keys_dissector,
flow_keys_dissector_keys,
ARRAY_SIZE(flow_keys_dissector_keys));
skb_flow_dissector_init(&flow_keys_dissector_symmetric,
flow_keys_dissector_symmetric_keys,
ARRAY_SIZE(flow_keys_dissector_symmetric_keys));
skb_flow_dissector_init(&flow_keys_basic_dissector,
flow_keys_basic_dissector_keys,
ARRAY_SIZE(flow_keys_basic_dissector_keys));
return 0;
}
core_initcall(init_default_flow_dissectors);
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