This patch white list some tcp cong helper functions, tcp_slow_start()
and tcp_cong_avoid_ai(). They are allowed to be directly called by
the bpf-tcp-cc program.
A few tcp cc implementation functions are also white listed.
A potential use case is the bpf-tcp-cc implementation may only
want to override a subset of a tcp_congestion_ops. For others,
the bpf-tcp-cc can directly call the kernel counter parts instead of
re-implementing (or copy-and-pasting) them to the bpf program.
They will only be available to the bpf-tcp-cc typed program.
The white listed functions are not bounded to a fixed ABI contract.
When any of them has changed, the bpf-tcp-cc program has to be changed
like any in-tree/out-of-tree kernel tcp-cc implementations do also.
Signed-off-by: Martin KaFai Lau <kafai@xxxxxx>
---
net/ipv4/bpf_tcp_ca.c | 41 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 41 insertions(+)
diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c
index d520e61649c8..ed6e6b5b762b 100644
--- a/net/ipv4/bpf_tcp_ca.c
+++ b/net/ipv4/bpf_tcp_ca.c
@@ -5,6 +5,7 @@
#include <linux/bpf_verifier.h>
#include <linux/bpf.h>
#include <linux/btf.h>
+#include <linux/btf_ids.h>
#include <linux/filter.h>
#include <net/tcp.h>
#include <net/bpf_sk_storage.h>
@@ -178,10 +179,50 @@ bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id,
}
}
+BTF_SET_START(bpf_tcp_ca_kfunc_ids)
+BTF_ID(func, tcp_reno_ssthresh)
+BTF_ID(func, tcp_reno_cong_avoid)
+BTF_ID(func, tcp_reno_undo_cwnd)
+BTF_ID(func, tcp_slow_start)
+BTF_ID(func, tcp_cong_avoid_ai)
+#if IS_BUILTIN(CONFIG_TCP_CONG_CUBIC)
+BTF_ID(func, cubictcp_init)
+BTF_ID(func, cubictcp_recalc_ssthresh)
+BTF_ID(func, cubictcp_cong_avoid)
+BTF_ID(func, cubictcp_state)
+BTF_ID(func, cubictcp_cwnd_event)
+BTF_ID(func, cubictcp_acked)
+#endif
+#if IS_BUILTIN(CONFIG_TCP_CONG_DCTCP)
+BTF_ID(func, dctcp_init)
+BTF_ID(func, dctcp_update_alpha)
+BTF_ID(func, dctcp_cwnd_event)
+BTF_ID(func, dctcp_ssthresh)
+BTF_ID(func, dctcp_cwnd_undo)
+BTF_ID(func, dctcp_state)
+#endif
+#if IS_BUILTIN(CONFIG_TCP_CONG_BBR)
+BTF_ID(func, bbr_init)
+BTF_ID(func, bbr_main)
+BTF_ID(func, bbr_sndbuf_expand)
+BTF_ID(func, bbr_undo_cwnd)
+BTF_ID(func, bbr_cwnd_even),
+BTF_ID(func, bbr_ssthresh)
+BTF_ID(func, bbr_min_tso_segs)
+BTF_ID(func, bbr_set_state)
+#endif
+BTF_SET_END(bpf_tcp_ca_kfunc_ids)
+
+static bool bpf_tcp_ca_check_kern_func_call(u32 kfunc_btf_id)
+{
+ return btf_id_set_contains(&bpf_tcp_ca_kfunc_ids, kfunc_btf_id);
+}
+
static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = {
.get_func_proto = bpf_tcp_ca_get_func_proto,
.is_valid_access = bpf_tcp_ca_is_valid_access,
.btf_struct_access = bpf_tcp_ca_btf_struct_access,
+ .check_kern_func_call = bpf_tcp_ca_check_kern_func_call,
};
static int bpf_tcp_ca_init_member(const struct btf_type *t,
--
2.30.2
