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flow_dissector: implements flow dissector BPF hook

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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:
Petar Penkov
2018-09-14 07:46:18 -07:00
committed by Alexei Starovoitov
parent 1edb6e035e
commit d58e468b11
10 changed files with 291 additions and 3 deletions
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8
kernel/bpf/syscall.c
View File

@@ -1615,6 +1615,9 @@ static int bpf_prog_attach(const union bpf_attr *attr)
case BPF_LIRC_MODE2:
ptype = BPF_PROG_TYPE_LIRC_MODE2;
break;
case BPF_FLOW_DISSECTOR:
ptype = BPF_PROG_TYPE_FLOW_DISSECTOR;
break;
default:
return -EINVAL;
}
@@ -1636,6 +1639,9 @@ static int bpf_prog_attach(const union bpf_attr *attr)
case BPF_PROG_TYPE_LIRC_MODE2:
ret = lirc_prog_attach(attr, prog);
break;
case BPF_PROG_TYPE_FLOW_DISSECTOR:
ret = skb_flow_dissector_bpf_prog_attach(attr, prog);
break;
default:
ret = cgroup_bpf_prog_attach(attr, ptype, prog);
}
@@ -1688,6 +1694,8 @@ static int bpf_prog_detach(const union bpf_attr *attr)
return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, NULL);
case BPF_LIRC_MODE2:
return lirc_prog_detach(attr);
case BPF_FLOW_DISSECTOR:
return skb_flow_dissector_bpf_prog_detach(attr);
default:
return -EINVAL;
}

32
kernel/bpf/verifier.c
View File

@@ -261,6 +261,7 @@ static const char * const reg_type_str[] = {
[PTR_TO_PACKET] = "pkt",
[PTR_TO_PACKET_META] = "pkt_meta",
[PTR_TO_PACKET_END] = "pkt_end",
[PTR_TO_FLOW_KEYS] = "flow_keys",
};
static char slot_type_char[] = {
@@ -965,6 +966,7 @@ static bool is_spillable_regtype(enum bpf_reg_type type)
case PTR_TO_PACKET:
case PTR_TO_PACKET_META:
case PTR_TO_PACKET_END:
case PTR_TO_FLOW_KEYS:
case CONST_PTR_TO_MAP:
return true;
default:
@@ -1238,6 +1240,7 @@ static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
case BPF_PROG_TYPE_LWT_XMIT:
case BPF_PROG_TYPE_SK_SKB:
case BPF_PROG_TYPE_SK_MSG:
case BPF_PROG_TYPE_FLOW_DISSECTOR:
if (meta)
return meta->pkt_access;
@@ -1321,6 +1324,18 @@ static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off,
return -EACCES;
}
static int check_flow_keys_access(struct bpf_verifier_env *env, int off,
int size)
{
if (size < 0 || off < 0 ||
(u64)off + size > sizeof(struct bpf_flow_keys)) {
verbose(env, "invalid access to flow keys off=%d size=%d\n",
off, size);
return -EACCES;
}
return 0;
}
static bool __is_pointer_value(bool allow_ptr_leaks,
const struct bpf_reg_state *reg)
{
@@ -1422,6 +1437,9 @@ static int check_ptr_alignment(struct bpf_verifier_env *env,
* right in front, treat it the very same way.
*/
return check_pkt_ptr_alignment(env, reg, off, size, strict);
case PTR_TO_FLOW_KEYS:
pointer_desc = "flow keys ";
break;
case PTR_TO_MAP_VALUE:
pointer_desc = "value ";
break;
@@ -1692,6 +1710,17 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn
err = check_packet_access(env, regno, off, size, false);
if (!err && t == BPF_READ && value_regno >= 0)
mark_reg_unknown(env, regs, value_regno);
} else if (reg->type == PTR_TO_FLOW_KEYS) {
if (t == BPF_WRITE && value_regno >= 0 &&
is_pointer_value(env, value_regno)) {
verbose(env, "R%d leaks addr into flow keys\n",
value_regno);
return -EACCES;
}
err = check_flow_keys_access(env, off, size);
if (!err && t == BPF_READ && value_regno >= 0)
mark_reg_unknown(env, regs, value_regno);
} else {
verbose(env, "R%d invalid mem access '%s'\n", regno,
reg_type_str[reg->type]);
@@ -1839,6 +1868,8 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
case PTR_TO_PACKET_META:
return check_packet_access(env, regno, reg->off, access_size,
zero_size_allowed);
case PTR_TO_FLOW_KEYS:
return check_flow_keys_access(env, reg->off, access_size);
case PTR_TO_MAP_VALUE:
return check_map_access(env, regno, reg->off, access_size,
zero_size_allowed);
@@ -4366,6 +4397,7 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
case PTR_TO_CTX:
case CONST_PTR_TO_MAP:
case PTR_TO_PACKET_END:
case PTR_TO_FLOW_KEYS:
/* Only valid matches are exact, which memcmp() above
* would have accepted
*/