From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4EF54BA46 for ; Tue, 7 Mar 2023 18:10:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C759EC433EF; Tue, 7 Mar 2023 18:10:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678212644; bh=Od0/u2N5OZSIc5LZ756uAyP/R1uteBASlcbwcJHfmaw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hLGC/kAoBUZ9mcw1O97Yt1vMp7xC7robanZiYps4GQOr1s9mDE4skEc1Min9SaQgR AkNwsQFw1GAsE9ZxTVuVHDjTpnQPnU7VtQxbVVc3i3WSpSbvXdV6/feaZXMXNZ7gw+ qVw0HoTSZbZ8HWf9zMSiihMcwrr/rJXNgHqVN4tI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Andrii Nakryiko , Daniel Borkmann , Stanislav Fomichev , Sasha Levin Subject: [PATCH 6.1 251/885] bpf: Fix global subprog context argument resolution logic Date: Tue, 7 Mar 2023 17:53:05 +0100 Message-Id: <20230307170012.907207266@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307170001.594919529@linuxfoundation.org> References: <20230307170001.594919529@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Andrii Nakryiko [ Upstream commit d384dce281ed1b504fae2e279507827638d56fa3 ] KPROBE program's user-facing context type is defined as typedef bpf_user_pt_regs_t. This leads to a problem when trying to passing kprobe/uprobe/usdt context argument into global subprog, as kernel always strip away mods and typedefs of user-supplied type, but takes expected type from bpf_ctx_convert as is, which causes mismatch. Current way to work around this is to define a fake struct with the same name as expected typedef: struct bpf_user_pt_regs_t {}; __noinline my_global_subprog(struct bpf_user_pt_regs_t *ctx) { ... } This patch fixes the issue by resolving expected type, if it's not a struct. It still leaves the above work-around working for backwards compatibility. Fixes: 91cc1a99740e ("bpf: Annotate context types") Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Stanislav Fomichev Link: https://lore.kernel.org/bpf/20230216045954.3002473-2-andrii@kernel.org Signed-off-by: Sasha Levin --- kernel/bpf/btf.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index a7c2f0c3fc19c..7fcbe5d002070 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -5131,6 +5131,7 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, if (!ctx_struct) /* should not happen */ return NULL; +again: ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_struct->name_off); if (!ctx_tname) { /* should not happen */ @@ -5144,8 +5145,16 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf, * int socket_filter_bpf_prog(struct __sk_buff *skb) * { // no fields of skb are ever used } */ - if (strcmp(ctx_tname, tname)) - return NULL; + if (strcmp(ctx_tname, tname)) { + /* bpf_user_pt_regs_t is a typedef, so resolve it to + * underlying struct and check name again + */ + if (!btf_type_is_modifier(ctx_struct)) + return NULL; + while (btf_type_is_modifier(ctx_struct)) + ctx_struct = btf_type_by_id(btf_vmlinux, ctx_struct->type); + goto again; + } return ctx_type; } -- 2.39.2