From e42ac14180554fa23a3312d4f921dc4ea7972fb7 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Mon, 22 Jul 2024 11:30:45 -0700 Subject: bpf: Check unsupported ops from the bpf_struct_ops's cfi_stubs The bpf_tcp_ca struct_ops currently uses a "u32 unsupported_ops[]" array to track which ops is not supported. After cfi_stubs had been added, the function pointer in cfi_stubs is also NULL for the unsupported ops. Thus, the "u32 unsupported_ops[]" becomes redundant. This observation was originally brought up in the bpf/cfi discussion: https://lore.kernel.org/bpf/CAADnVQJoEkdjyCEJRPASjBw1QGsKYrF33QdMGc1RZa9b88bAEA@mail.gmail.com/ The recent bpf qdisc patch (https://lore.kernel.org/bpf/20240714175130.4051012-6-amery.hung@bytedance.com/) also needs to specify quite many unsupported ops. It is a good time to clean it up. This patch removes the need of "u32 unsupported_ops[]" and tests for null-ness in the cfi_stubs instead. Testing the cfi_stubs is done in a new function bpf_struct_ops_supported(). The verifier will call bpf_struct_ops_supported() when loading the struct_ops program. The ".check_member" is removed from the bpf_tcp_ca in this patch. ".check_member" could still be useful for other subsytems to enforce other restrictions (e.g. sched_ext checks for prog->sleepable). To keep the same error return, ENOTSUPP is used. Cc: Amery Hung Signed-off-by: Martin KaFai Lau Link: https://lore.kernel.org/r/20240722183049.2254692-2-martin.lau@linux.dev Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko --- net/ipv4/bpf_tcp_ca.c | 26 -------------------------- 1 file changed, 26 deletions(-) (limited to 'net/ipv4') diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c index 3f88d0961e5b..554804774628 100644 --- a/net/ipv4/bpf_tcp_ca.c +++ b/net/ipv4/bpf_tcp_ca.c @@ -14,10 +14,6 @@ /* "extern" is to avoid sparse warning. It is only used in bpf_struct_ops.c. */ static struct bpf_struct_ops bpf_tcp_congestion_ops; -static u32 unsupported_ops[] = { - offsetof(struct tcp_congestion_ops, get_info), -}; - static const struct btf_type *tcp_sock_type; static u32 tcp_sock_id, sock_id; static const struct btf_type *tcp_congestion_ops_type; @@ -45,18 +41,6 @@ static int bpf_tcp_ca_init(struct btf *btf) return 0; } -static bool is_unsupported(u32 member_offset) -{ - unsigned int i; - - for (i = 0; i < ARRAY_SIZE(unsupported_ops); i++) { - if (member_offset == unsupported_ops[i]) - return true; - } - - return false; -} - static bool bpf_tcp_ca_is_valid_access(int off, int size, enum bpf_access_type type, const struct bpf_prog *prog, @@ -251,15 +235,6 @@ static int bpf_tcp_ca_init_member(const struct btf_type *t, return 0; } -static int bpf_tcp_ca_check_member(const struct btf_type *t, - const struct btf_member *member, - const struct bpf_prog *prog) -{ - if (is_unsupported(__btf_member_bit_offset(t, member) / 8)) - return -ENOTSUPP; - return 0; -} - static int bpf_tcp_ca_reg(void *kdata, struct bpf_link *link) { return tcp_register_congestion_control(kdata); @@ -354,7 +329,6 @@ static struct bpf_struct_ops bpf_tcp_congestion_ops = { .reg = bpf_tcp_ca_reg, .unreg = bpf_tcp_ca_unreg, .update = bpf_tcp_ca_update, - .check_member = bpf_tcp_ca_check_member, .init_member = bpf_tcp_ca_init_member, .init = bpf_tcp_ca_init, .validate = bpf_tcp_ca_validate, -- cgit v1.2.3