flow_dissector: implements flow dissector BPF hook
Adds a hook for programs of type BPF_PROG_TYPE_FLOW_DISSECTOR and attach type BPF_FLOW_DISSECTOR that is executed in the flow dissector path. The BPF program is per-network namespace. Signed-off-by: Petar Penkov <ppenkov@google.com> Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
parent
1edb6e035e
commit
d58e468b11
@ -212,6 +212,7 @@ enum bpf_reg_type {
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PTR_TO_PACKET_META, /* skb->data - meta_len */
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PTR_TO_PACKET, /* reg points to skb->data */
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PTR_TO_PACKET_END, /* skb->data + headlen */
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PTR_TO_FLOW_KEYS, /* reg points to bpf_flow_keys */
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};
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/* The information passed from prog-specific *_is_valid_access
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@ -32,6 +32,7 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_LIRC_MODE2, lirc_mode2)
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#ifdef CONFIG_INET
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BPF_PROG_TYPE(BPF_PROG_TYPE_SK_REUSEPORT, sk_reuseport)
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#endif
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BPF_PROG_TYPE(BPF_PROG_TYPE_FLOW_DISSECTOR, flow_dissector)
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BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
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BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)
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@ -243,6 +243,8 @@ struct scatterlist;
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struct pipe_inode_info;
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struct iov_iter;
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struct napi_struct;
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struct bpf_prog;
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union bpf_attr;
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#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
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struct nf_conntrack {
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@ -1192,6 +1194,11 @@ void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
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const struct flow_dissector_key *key,
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unsigned int key_count);
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int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
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struct bpf_prog *prog);
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int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr);
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bool __skb_flow_dissect(const struct sk_buff *skb,
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struct flow_dissector *flow_dissector,
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void *target_container,
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@ -43,6 +43,7 @@ struct ctl_table_header;
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struct net_generic;
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struct uevent_sock;
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struct netns_ipvs;
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struct bpf_prog;
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#define NETDEV_HASHBITS 8
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@ -145,6 +146,8 @@ struct net {
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#endif
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struct net_generic __rcu *gen;
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struct bpf_prog __rcu *flow_dissector_prog;
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/* Note : following structs are cache line aligned */
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#ifdef CONFIG_XFRM
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struct netns_xfrm xfrm;
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@ -19,6 +19,7 @@ struct Qdisc_ops;
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struct qdisc_walker;
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struct tcf_walker;
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struct module;
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struct bpf_flow_keys;
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typedef int tc_setup_cb_t(enum tc_setup_type type,
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void *type_data, void *cb_priv);
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@ -307,9 +308,14 @@ struct tcf_proto {
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};
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struct qdisc_skb_cb {
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union {
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struct {
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unsigned int pkt_len;
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u16 slave_dev_queue_mapping;
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u16 tc_classid;
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};
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struct bpf_flow_keys *flow_keys;
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};
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#define QDISC_CB_PRIV_LEN 20
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unsigned char data[QDISC_CB_PRIV_LEN];
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};
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@ -152,6 +152,7 @@ enum bpf_prog_type {
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BPF_PROG_TYPE_LWT_SEG6LOCAL,
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BPF_PROG_TYPE_LIRC_MODE2,
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BPF_PROG_TYPE_SK_REUSEPORT,
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BPF_PROG_TYPE_FLOW_DISSECTOR,
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};
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enum bpf_attach_type {
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@ -172,6 +173,7 @@ enum bpf_attach_type {
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BPF_CGROUP_UDP4_SENDMSG,
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BPF_CGROUP_UDP6_SENDMSG,
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BPF_LIRC_MODE2,
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BPF_FLOW_DISSECTOR,
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__MAX_BPF_ATTACH_TYPE
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};
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@ -2333,6 +2335,7 @@ struct __sk_buff {
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/* ... here. */
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__u32 data_meta;
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struct bpf_flow_keys *flow_keys;
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};
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struct bpf_tunnel_key {
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@ -2778,4 +2781,27 @@ enum bpf_task_fd_type {
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BPF_FD_TYPE_URETPROBE, /* filename + offset */
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};
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struct bpf_flow_keys {
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__u16 nhoff;
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__u16 thoff;
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__u16 addr_proto; /* ETH_P_* of valid addrs */
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__u8 is_frag;
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__u8 is_first_frag;
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__u8 is_encap;
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__u8 ip_proto;
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__be16 n_proto;
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__be16 sport;
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__be16 dport;
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union {
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struct {
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__be32 ipv4_src;
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__be32 ipv4_dst;
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};
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struct {
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__u32 ipv6_src[4]; /* in6_addr; network order */
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__u32 ipv6_dst[4]; /* in6_addr; network order */
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};
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};
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};
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#endif /* _UAPI__LINUX_BPF_H__ */
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@ -1615,6 +1615,9 @@ static int bpf_prog_attach(const union bpf_attr *attr)
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case BPF_LIRC_MODE2:
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ptype = BPF_PROG_TYPE_LIRC_MODE2;
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break;
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case BPF_FLOW_DISSECTOR:
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ptype = BPF_PROG_TYPE_FLOW_DISSECTOR;
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break;
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default:
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return -EINVAL;
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}
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@ -1636,6 +1639,9 @@ static int bpf_prog_attach(const union bpf_attr *attr)
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case BPF_PROG_TYPE_LIRC_MODE2:
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ret = lirc_prog_attach(attr, prog);
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break;
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case BPF_PROG_TYPE_FLOW_DISSECTOR:
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ret = skb_flow_dissector_bpf_prog_attach(attr, prog);
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break;
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default:
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ret = cgroup_bpf_prog_attach(attr, ptype, prog);
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}
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@ -1688,6 +1694,8 @@ static int bpf_prog_detach(const union bpf_attr *attr)
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return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, NULL);
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case BPF_LIRC_MODE2:
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return lirc_prog_detach(attr);
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case BPF_FLOW_DISSECTOR:
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return skb_flow_dissector_bpf_prog_detach(attr);
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default:
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return -EINVAL;
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}
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@ -261,6 +261,7 @@ static const char * const reg_type_str[] = {
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[PTR_TO_PACKET] = "pkt",
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[PTR_TO_PACKET_META] = "pkt_meta",
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[PTR_TO_PACKET_END] = "pkt_end",
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[PTR_TO_FLOW_KEYS] = "flow_keys",
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};
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static char slot_type_char[] = {
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@ -965,6 +966,7 @@ static bool is_spillable_regtype(enum bpf_reg_type type)
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case PTR_TO_PACKET:
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case PTR_TO_PACKET_META:
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case PTR_TO_PACKET_END:
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case PTR_TO_FLOW_KEYS:
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case CONST_PTR_TO_MAP:
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return true;
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default:
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@ -1238,6 +1240,7 @@ static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
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case BPF_PROG_TYPE_LWT_XMIT:
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case BPF_PROG_TYPE_SK_SKB:
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case BPF_PROG_TYPE_SK_MSG:
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case BPF_PROG_TYPE_FLOW_DISSECTOR:
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if (meta)
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return meta->pkt_access;
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@ -1321,6 +1324,18 @@ static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off,
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return -EACCES;
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}
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static int check_flow_keys_access(struct bpf_verifier_env *env, int off,
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int size)
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{
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if (size < 0 || off < 0 ||
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(u64)off + size > sizeof(struct bpf_flow_keys)) {
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verbose(env, "invalid access to flow keys off=%d size=%d\n",
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off, size);
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return -EACCES;
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}
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return 0;
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}
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static bool __is_pointer_value(bool allow_ptr_leaks,
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const struct bpf_reg_state *reg)
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{
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@ -1422,6 +1437,9 @@ static int check_ptr_alignment(struct bpf_verifier_env *env,
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* right in front, treat it the very same way.
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*/
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return check_pkt_ptr_alignment(env, reg, off, size, strict);
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case PTR_TO_FLOW_KEYS:
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pointer_desc = "flow keys ";
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break;
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case PTR_TO_MAP_VALUE:
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pointer_desc = "value ";
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break;
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@ -1692,6 +1710,17 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
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err = check_packet_access(env, regno, off, size, false);
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if (!err && t == BPF_READ && value_regno >= 0)
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mark_reg_unknown(env, regs, value_regno);
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} else if (reg->type == PTR_TO_FLOW_KEYS) {
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if (t == BPF_WRITE && value_regno >= 0 &&
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is_pointer_value(env, value_regno)) {
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verbose(env, "R%d leaks addr into flow keys\n",
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value_regno);
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return -EACCES;
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}
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err = check_flow_keys_access(env, off, size);
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if (!err && t == BPF_READ && value_regno >= 0)
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mark_reg_unknown(env, regs, value_regno);
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} else {
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verbose(env, "R%d invalid mem access '%s'\n", regno,
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reg_type_str[reg->type]);
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@ -1839,6 +1868,8 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
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case PTR_TO_PACKET_META:
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return check_packet_access(env, regno, reg->off, access_size,
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zero_size_allowed);
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case PTR_TO_FLOW_KEYS:
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return check_flow_keys_access(env, reg->off, access_size);
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case PTR_TO_MAP_VALUE:
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return check_map_access(env, regno, reg->off, access_size,
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zero_size_allowed);
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@ -4366,6 +4397,7 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
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case PTR_TO_CTX:
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case CONST_PTR_TO_MAP:
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case PTR_TO_PACKET_END:
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case PTR_TO_FLOW_KEYS:
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/* Only valid matches are exact, which memcmp() above
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* would have accepted
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*/
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@ -5123,6 +5123,17 @@ sk_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
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}
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}
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static const struct bpf_func_proto *
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flow_dissector_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
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{
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switch (func_id) {
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case BPF_FUNC_skb_load_bytes:
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return &bpf_skb_load_bytes_proto;
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default:
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return bpf_base_func_proto(func_id);
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}
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}
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static const struct bpf_func_proto *
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lwt_out_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
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{
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@ -5241,6 +5252,10 @@ static bool bpf_skb_is_valid_access(int off, int size, enum bpf_access_type type
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if (size != size_default)
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return false;
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break;
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case bpf_ctx_range(struct __sk_buff, flow_keys):
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if (size != sizeof(struct bpf_flow_keys *))
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return false;
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break;
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default:
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/* Only narrow read access allowed for now. */
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if (type == BPF_WRITE) {
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@ -5266,6 +5281,7 @@ static bool sk_filter_is_valid_access(int off, int size,
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case bpf_ctx_range(struct __sk_buff, data):
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case bpf_ctx_range(struct __sk_buff, data_meta):
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case bpf_ctx_range(struct __sk_buff, data_end):
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case bpf_ctx_range(struct __sk_buff, flow_keys):
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case bpf_ctx_range_till(struct __sk_buff, family, local_port):
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return false;
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}
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@ -5291,6 +5307,7 @@ static bool lwt_is_valid_access(int off, int size,
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case bpf_ctx_range(struct __sk_buff, tc_classid):
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case bpf_ctx_range_till(struct __sk_buff, family, local_port):
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case bpf_ctx_range(struct __sk_buff, data_meta):
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case bpf_ctx_range(struct __sk_buff, flow_keys):
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return false;
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}
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@ -5501,6 +5518,7 @@ static bool tc_cls_act_is_valid_access(int off, int size,
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case bpf_ctx_range(struct __sk_buff, data_end):
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info->reg_type = PTR_TO_PACKET_END;
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break;
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case bpf_ctx_range(struct __sk_buff, flow_keys):
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case bpf_ctx_range_till(struct __sk_buff, family, local_port):
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return false;
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}
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@ -5702,6 +5720,7 @@ static bool sk_skb_is_valid_access(int off, int size,
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switch (off) {
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case bpf_ctx_range(struct __sk_buff, tc_classid):
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case bpf_ctx_range(struct __sk_buff, data_meta):
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case bpf_ctx_range(struct __sk_buff, flow_keys):
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return false;
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}
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@ -5761,6 +5780,39 @@ static bool sk_msg_is_valid_access(int off, int size,
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return true;
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}
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static bool flow_dissector_is_valid_access(int off, int size,
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enum bpf_access_type type,
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const struct bpf_prog *prog,
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struct bpf_insn_access_aux *info)
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{
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if (type == BPF_WRITE) {
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switch (off) {
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case bpf_ctx_range_till(struct __sk_buff, cb[0], cb[4]):
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break;
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default:
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return false;
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}
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}
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switch (off) {
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case bpf_ctx_range(struct __sk_buff, data):
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info->reg_type = PTR_TO_PACKET;
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break;
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case bpf_ctx_range(struct __sk_buff, data_end):
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info->reg_type = PTR_TO_PACKET_END;
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break;
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case bpf_ctx_range(struct __sk_buff, flow_keys):
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info->reg_type = PTR_TO_FLOW_KEYS;
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break;
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case bpf_ctx_range(struct __sk_buff, tc_classid):
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case bpf_ctx_range(struct __sk_buff, data_meta):
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case bpf_ctx_range_till(struct __sk_buff, family, local_port):
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return false;
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}
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return bpf_skb_is_valid_access(off, size, type, prog, info);
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}
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static u32 bpf_convert_ctx_access(enum bpf_access_type type,
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const struct bpf_insn *si,
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struct bpf_insn *insn_buf,
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@ -6055,6 +6107,15 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type,
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bpf_target_off(struct sock_common,
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skc_num, 2, target_size));
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break;
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case offsetof(struct __sk_buff, flow_keys):
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off = si->off;
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off -= offsetof(struct __sk_buff, flow_keys);
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off += offsetof(struct sk_buff, cb);
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off += offsetof(struct qdisc_skb_cb, flow_keys);
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*insn++ = BPF_LDX_MEM(BPF_SIZEOF(void *), si->dst_reg,
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si->src_reg, off);
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break;
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}
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return insn - insn_buf;
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@ -7018,6 +7079,15 @@ const struct bpf_verifier_ops sk_msg_verifier_ops = {
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const struct bpf_prog_ops sk_msg_prog_ops = {
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};
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const struct bpf_verifier_ops flow_dissector_verifier_ops = {
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.get_func_proto = flow_dissector_func_proto,
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.is_valid_access = flow_dissector_is_valid_access,
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.convert_ctx_access = bpf_convert_ctx_access,
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};
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const struct bpf_prog_ops flow_dissector_prog_ops = {
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};
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int sk_detach_filter(struct sock *sk)
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{
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int ret = -ENOENT;
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@ -25,6 +25,9 @@
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#include <net/flow_dissector.h>
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#include <scsi/fc/fc_fcoe.h>
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#include <uapi/linux/batadv_packet.h>
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#include <linux/bpf.h>
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static DEFINE_MUTEX(flow_dissector_mutex);
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static void dissector_set_key(struct flow_dissector *flow_dissector,
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enum flow_dissector_key_id key_id)
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@ -62,6 +65,44 @@ void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
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}
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EXPORT_SYMBOL(skb_flow_dissector_init);
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int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
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struct bpf_prog *prog)
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{
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struct bpf_prog *attached;
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struct net *net;
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net = current->nsproxy->net_ns;
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mutex_lock(&flow_dissector_mutex);
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attached = rcu_dereference_protected(net->flow_dissector_prog,
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lockdep_is_held(&flow_dissector_mutex));
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if (attached) {
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/* Only one BPF program can be attached at a time */
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mutex_unlock(&flow_dissector_mutex);
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return -EEXIST;
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}
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rcu_assign_pointer(net->flow_dissector_prog, prog);
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mutex_unlock(&flow_dissector_mutex);
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return 0;
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}
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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;
|
||||
}
|
||||
bpf_prog_put(attached);
|
||||
RCU_INIT_POINTER(net->flow_dissector_prog, NULL);
|
||||
mutex_unlock(&flow_dissector_mutex);
|
||||
return 0;
|
||||
}
|
||||
/**
|
||||
* skb_flow_get_be16 - extract be16 entity
|
||||
* @skb: sk_buff to extract from
|
||||
@ -588,6 +629,60 @@ static bool skb_flow_dissect_allowed(int *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_control *key_control;
|
||||
struct flow_dissector_key_basic *key_basic;
|
||||
struct flow_dissector_key_addrs *key_addrs;
|
||||
struct flow_dissector_key_ports *key_ports;
|
||||
|
||||
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);
|
||||
key_ports->src = flow_keys->sport;
|
||||
key_ports->dst = flow_keys->dport;
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* __skb_flow_dissect - extract the flow_keys struct and return it
|
||||
* @skb: sk_buff to extract the flow from, can be NULL if the rest are specified
|
||||
@ -619,6 +714,7 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
|
||||
struct flow_dissector_key_vlan *key_vlan;
|
||||
enum flow_dissect_ret fdret;
|
||||
enum flow_dissector_key_id dissector_vlan = FLOW_DISSECTOR_KEY_MAX;
|
||||
struct bpf_prog *attached;
|
||||
int num_hdrs = 0;
|
||||
u8 ip_proto = 0;
|
||||
bool ret;
|
||||
@ -658,6 +754,44 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
|
||||
FLOW_DISSECTOR_KEY_BASIC,
|
||||
target_container);
|
||||
|
||||
rcu_read_lock();
|
||||
attached = skb ? rcu_dereference(dev_net(skb->dev)->flow_dissector_prog)
|
||||
: NULL;
|
||||
if (attached) {
|
||||
/* Note that even though the const qualifier is discarded
|
||||
* throughout the execution of the BPF program, all changes(the
|
||||
* control block) are reverted after the BPF program returns.
|
||||
* Therefore, __skb_flow_dissect does not alter the skb.
|
||||
*/
|
||||
struct bpf_flow_keys flow_keys = {};
|
||||
struct bpf_skb_data_end cb_saved;
|
||||
struct bpf_skb_data_end *cb;
|
||||
u32 result;
|
||||
|
||||
cb = (struct bpf_skb_data_end *)skb->cb;
|
||||
|
||||
/* Save Control Block */
|
||||
memcpy(&cb_saved, cb, sizeof(cb_saved));
|
||||
memset(cb, 0, sizeof(cb_saved));
|
||||
|
||||
/* Pass parameters to the BPF program */
|
||||
cb->qdisc_cb.flow_keys = &flow_keys;
|
||||
flow_keys.nhoff = nhoff;
|
||||
|
||||
bpf_compute_data_pointers((struct sk_buff *)skb);
|
||||
result = BPF_PROG_RUN(attached, skb);
|
||||
|
||||
/* Restore state */
|
||||
memcpy(cb, &cb_saved, sizeof(cb_saved));
|
||||
|
||||
__skb_flow_bpf_to_target(&flow_keys, flow_dissector,
|
||||
target_container);
|
||||
key_control->thoff = min_t(u16, key_control->thoff, skb->len);
|
||||
rcu_read_unlock();
|
||||
return result == BPF_OK;
|
||||
}
|
||||
rcu_read_unlock();
|
||||
|
||||
if (dissector_uses_key(flow_dissector,
|
||||
FLOW_DISSECTOR_KEY_ETH_ADDRS)) {
|
||||
struct ethhdr *eth = eth_hdr(skb);
|
||||
|
Loading…
Reference in New Issue
Block a user