From 824c58fb1090ae5e502284400682e30841280a87 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 12 Feb 2024 15:32:19 -0800 Subject: bpf: handle bpf_user_pt_regs_t typedef explicitly for PTR_TO_CTX global arg Expected canonical argument type for global function arguments representing PTR_TO_CTX is `bpf_user_pt_regs_t *ctx`. This currently works on s390x by accident because kernel resolves such typedef to underlying struct (which is anonymous on s390x), and erroneously accepting it as expected context type. We are fixing this problem next, which would break s390x arch, so we need to handle `bpf_user_pt_regs_t` case explicitly for KPROBE programs. Fixes: 91cc1a99740e ("bpf: Annotate context types") Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240212233221.2575350-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/btf.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 405f95722905..26dc0876e426 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -5702,6 +5702,21 @@ bool btf_is_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, const char *tname, *ctx_tname; t = btf_type_by_id(btf, t->type); + + /* KPROBE programs allow bpf_user_pt_regs_t typedef, which we need to + * check before we skip all the typedef below. + */ + if (prog_type == BPF_PROG_TYPE_KPROBE) { + while (btf_type_is_modifier(t) && !btf_type_is_typedef(t)) + t = btf_type_by_id(btf, t->type); + + if (btf_type_is_typedef(t)) { + tname = btf_name_by_offset(btf, t->name_off); + if (tname && strcmp(tname, "bpf_user_pt_regs_t") == 0) + return true; + } + } + while (btf_type_is_modifier(t)) t = btf_type_by_id(btf, t->type); if (!btf_type_is_struct(t)) { -- cgit