summaryrefslogtreecommitdiffstats
path: root/net/core
diff options
context:
space:
mode:
authorAndrey Ignatov <rdna@fb.com>2018-05-25 08:55:23 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2018-05-28 17:41:02 +0200
commit1cedee13d25ab118d325f95588c1a084e9317229 (patch)
tree63f5cd82b008d63091bac31168253e3af6a1ba6c /net/core
parent13193b0f392f5a65d0d54185cb95ed5e99c0a5bf (diff)
downloadop-kernel-dev-1cedee13d25ab118d325f95588c1a084e9317229.zip
op-kernel-dev-1cedee13d25ab118d325f95588c1a084e9317229.tar.gz
bpf: Hooks for sys_sendmsg
In addition to already existing BPF hooks for sys_bind and sys_connect, the patch provides new hooks for sys_sendmsg. It leverages existing BPF program type `BPF_PROG_TYPE_CGROUP_SOCK_ADDR` that provides access to socket itlself (properties like family, type, protocol) and user-passed `struct sockaddr *` so that BPF program can override destination IP and port for system calls such as sendto(2) or sendmsg(2) and/or assign source IP to the socket. The hooks are implemented as two new attach types: `BPF_CGROUP_UDP4_SENDMSG` and `BPF_CGROUP_UDP6_SENDMSG` for UDPv4 and UDPv6 correspondingly. UDPv4 and UDPv6 separate attach types for same reason as sys_bind and sys_connect hooks, i.e. to prevent reading from / writing to e.g. user_ip6 fields when user passes sockaddr_in since it'd be out-of-bound. The difference with already existing hooks is sys_sendmsg are implemented only for unconnected UDP. For TCP it doesn't make sense to change user-provided `struct sockaddr *` at sendto(2)/sendmsg(2) time since socket either was already connected and has source/destination set or wasn't connected and call to sendto(2)/sendmsg(2) would lead to ENOTCONN anyway. Connected UDP is already handled by sys_connect hooks that can override source/destination at connect time and use fast-path later, i.e. these hooks don't affect UDP fast-path. Rewriting source IP is implemented differently than that in sys_connect hooks. When sys_sendmsg is used with unconnected UDP it doesn't work to just bind socket to desired local IP address since source IP can be set on per-packet basis by using ancillary data (cmsg(3)). So no matter if socket is bound or not, source IP has to be rewritten on every call to sys_sendmsg. To do so two new fields are added to UAPI `struct bpf_sock_addr`; * `msg_src_ip4` to set source IPv4 for UDPv4; * `msg_src_ip6` to set source IPv6 for UDPv6. Signed-off-by: Andrey Ignatov <rdna@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/filter.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/net/core/filter.c b/net/core/filter.c
index acf1f4f..24e6ce8 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5299,6 +5299,7 @@ static bool sock_addr_is_valid_access(int off, int size,
switch (prog->expected_attach_type) {
case BPF_CGROUP_INET4_BIND:
case BPF_CGROUP_INET4_CONNECT:
+ case BPF_CGROUP_UDP4_SENDMSG:
break;
default:
return false;
@@ -5308,6 +5309,24 @@ static bool sock_addr_is_valid_access(int off, int size,
switch (prog->expected_attach_type) {
case BPF_CGROUP_INET6_BIND:
case BPF_CGROUP_INET6_CONNECT:
+ case BPF_CGROUP_UDP6_SENDMSG:
+ break;
+ default:
+ return false;
+ }
+ break;
+ case bpf_ctx_range(struct bpf_sock_addr, msg_src_ip4):
+ switch (prog->expected_attach_type) {
+ case BPF_CGROUP_UDP4_SENDMSG:
+ break;
+ default:
+ return false;
+ }
+ break;
+ case bpf_ctx_range_till(struct bpf_sock_addr, msg_src_ip6[0],
+ msg_src_ip6[3]):
+ switch (prog->expected_attach_type) {
+ case BPF_CGROUP_UDP6_SENDMSG:
break;
default:
return false;
@@ -5318,6 +5337,9 @@ static bool sock_addr_is_valid_access(int off, int size,
switch (off) {
case bpf_ctx_range(struct bpf_sock_addr, user_ip4):
case bpf_ctx_range_till(struct bpf_sock_addr, user_ip6[0], user_ip6[3]):
+ case bpf_ctx_range(struct bpf_sock_addr, msg_src_ip4):
+ case bpf_ctx_range_till(struct bpf_sock_addr, msg_src_ip6[0],
+ msg_src_ip6[3]):
/* Only narrow read access allowed for now. */
if (type == BPF_READ) {
bpf_ctx_record_field_size(info, size_default);
@@ -6072,6 +6094,23 @@ static u32 sock_addr_convert_ctx_access(enum bpf_access_type type,
*insn++ = BPF_ALU32_IMM(BPF_RSH, si->dst_reg,
SK_FL_PROTO_SHIFT);
break;
+
+ case offsetof(struct bpf_sock_addr, msg_src_ip4):
+ /* Treat t_ctx as struct in_addr for msg_src_ip4. */
+ SOCK_ADDR_LOAD_OR_STORE_NESTED_FIELD_SIZE_OFF(
+ struct bpf_sock_addr_kern, struct in_addr, t_ctx,
+ s_addr, BPF_SIZE(si->code), 0, tmp_reg);
+ break;
+
+ case bpf_ctx_range_till(struct bpf_sock_addr, msg_src_ip6[0],
+ msg_src_ip6[3]):
+ off = si->off;
+ off -= offsetof(struct bpf_sock_addr, msg_src_ip6[0]);
+ /* Treat t_ctx as struct in6_addr for msg_src_ip6. */
+ SOCK_ADDR_LOAD_OR_STORE_NESTED_FIELD_SIZE_OFF(
+ struct bpf_sock_addr_kern, struct in6_addr, t_ctx,
+ s6_addr32[0], BPF_SIZE(si->code), off, tmp_reg);
+ break;
}
return insn - insn_buf;
OpenPOWER on IntegriCloud