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Merge branch 'Do not limit cb_flags when creating child sk'

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Martin KaFai says:

====================
This set fixes an issue that the bpf_skops_init_child() unnecessarily
limited the child sk from inheriting all bpf_sock_ops_cb_flags
of the listen sk.  It also adds a test to check that.
====================

Tested-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2020-10-02 11:34:48 -07:00
commit 440c5752a3
6 changed files with 22 additions and 40 deletions
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33
include/net/tcp.h
View File

@ -2228,34 +2228,6 @@ int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
#endif /* CONFIG_NET_SOCK_MSG */
#ifdef CONFIG_CGROUP_BPF
/* Copy the listen sk's HDR_OPT_CB flags to its child.
*
* During 3-Way-HandShake, the synack is usually sent from
* the listen sk with the HDR_OPT_CB flags set so that
* bpf-prog will be called to write the BPF hdr option.
*
* In fastopen, the child sk is used to send synack instead
* of the listen sk. Thus, inheriting the HDR_OPT_CB flags
* from the listen sk gives the bpf-prog a chance to write
* BPF hdr option in the synack pkt during fastopen.
*
* Both fastopen and non-fastopen child will inherit the
* HDR_OPT_CB flags to keep the bpf-prog having a consistent
* behavior when deciding to clear this cb flags (or not)
* during the PASSIVE_ESTABLISHED_CB.
*
* In the future, other cb flags could be inherited here also.
*/
static inline void bpf_skops_init_child(const struct sock *sk,
struct sock *child)
{
tcp_sk(child)->bpf_sock_ops_cb_flags =
tcp_sk(sk)->bpf_sock_ops_cb_flags &
(BPF_SOCK_OPS_PARSE_ALL_HDR_OPT_CB_FLAG |
BPF_SOCK_OPS_PARSE_UNKNOWN_HDR_OPT_CB_FLAG |
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG);
}
static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
struct sk_buff *skb,
unsigned int end_offset)
@ -2264,11 +2236,6 @@ static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
skops->skb_data_end = skb->data + end_offset;
}
#else
static inline void bpf_skops_init_child(const struct sock *sk,
struct sock *child)
{
}
static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
struct sk_buff *skb,
unsigned int end_offset)

1
net/ipv4/tcp_minisocks.c
View File

@ -548,7 +548,6 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
newtp->fastopen_req = NULL;
RCU_INIT_POINTER(newtp->fastopen_rsk, NULL);
bpf_skops_init_child(sk, newsk);
tcp_bpf_clone(sk, newsk);
__TCP_INC_STATS(sock_net(sk), TCP_MIB_PASSIVEOPENS);

12
tools/testing/selftests/bpf/prog_tests/tcp_hdr_options.c
View File

@ -264,9 +264,19 @@ static int check_error_linum(const struct sk_fds *sk_fds)
static void check_hdr_and_close_fds(struct sk_fds *sk_fds)
{
const __u32 expected_inherit_cb_flags =
BPF_SOCK_OPS_PARSE_UNKNOWN_HDR_OPT_CB_FLAG |
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG |
BPF_SOCK_OPS_STATE_CB_FLAG;
if (sk_fds_shutdown(sk_fds))
goto check_linum;
if (CHECK(expected_inherit_cb_flags != skel->bss->inherit_cb_flags,
"Unexpected inherit_cb_flags", "0x%x != 0x%x\n",
skel->bss->inherit_cb_flags, expected_inherit_cb_flags))
goto check_linum;
if (check_hdr_stg(&exp_passive_hdr_stg, sk_fds->passive_fd,
"passive_hdr_stg"))
goto check_linum;
@ -321,6 +331,8 @@ static void reset_test(void)
memset(&skel->bss->active_estab_in, 0, optsize);
memset(&skel->bss->active_fin_in, 0, optsize);
skel->bss->inherit_cb_flags = 0;
skel->data->test_kind = TCPOPT_EXP;
skel->data->test_magic = 0xeB9F;

4
tools/testing/selftests/bpf/progs/test_misc_tcp_hdr_options.c
View File

@ -304,10 +304,10 @@ int misc_estab(struct bpf_sock_ops *skops)
passive_lport_n = __bpf_htons(passive_lport_h);
bpf_setsockopt(skops, SOL_TCP, TCP_SAVE_SYN,
&true_val, sizeof(true_val));
set_hdr_cb_flags(skops);
set_hdr_cb_flags(skops, 0);
break;
case BPF_SOCK_OPS_TCP_CONNECT_CB:
set_hdr_cb_flags(skops);
set_hdr_cb_flags(skops, 0);
break;
case BPF_SOCK_OPS_PARSE_HDR_OPT_CB:
return handle_parse_hdr(skops);

7
tools/testing/selftests/bpf/progs/test_tcp_hdr_options.c
View File

@ -21,6 +21,7 @@
__u8 test_kind = TCPOPT_EXP;
__u16 test_magic = 0xeB9F;
__u32 inherit_cb_flags = 0;
struct bpf_test_option passive_synack_out = {};
struct bpf_test_option passive_fin_out = {};
@ -467,6 +468,8 @@ static int handle_passive_estab(struct bpf_sock_ops *skops)
struct tcphdr *th;
int err;
inherit_cb_flags = skops->bpf_sock_ops_cb_flags;
err = load_option(skops, &passive_estab_in, true);
if (err == -ENOENT) {
/* saved_syn is not found. It was in syncookie mode.
@ -600,10 +603,10 @@ int estab(struct bpf_sock_ops *skops)
case BPF_SOCK_OPS_TCP_LISTEN_CB:
bpf_setsockopt(skops, SOL_TCP, TCP_SAVE_SYN,
&true_val, sizeof(true_val));
set_hdr_cb_flags(skops);
set_hdr_cb_flags(skops, BPF_SOCK_OPS_STATE_CB_FLAG);
break;
case BPF_SOCK_OPS_TCP_CONNECT_CB:
set_hdr_cb_flags(skops);
set_hdr_cb_flags(skops, 0);
break;
case BPF_SOCK_OPS_PARSE_HDR_OPT_CB:
return handle_parse_hdr(skops);

5
tools/testing/selftests/bpf/test_tcp_hdr_options.h
View File

@ -110,12 +110,13 @@ static inline void clear_hdr_cb_flags(struct bpf_sock_ops *skops)
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG));
}
static inline void set_hdr_cb_flags(struct bpf_sock_ops *skops)
static inline void set_hdr_cb_flags(struct bpf_sock_ops *skops, __u32 extra)
{
bpf_sock_ops_cb_flags_set(skops,
skops->bpf_sock_ops_cb_flags |
BPF_SOCK_OPS_PARSE_UNKNOWN_HDR_OPT_CB_FLAG |
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG);
BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG |
extra);
}
static inline void
clear_parse_all_hdr_cb_flags(struct bpf_sock_ops *skops)