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 6DD73BA49 for ; Tue, 7 Mar 2023 18:53:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E06A1C433D2; Tue, 7 Mar 2023 18:53:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678215199; bh=KUdxQlmNmo+5hThEmUOW/bmyIPVhpRue6udZs1OevTI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F7wR1yj8CcmYFID/LsPt0I9S4l7UTH/MgjYCPU5eLwu6pUV0dpQaw7mF4Zg9BlXfj uCXeyqa8TLP0Zwfkel9JZ3ZW6yHt0s/C5NLLSJVGRNkgRrPv07VbYQmAdCmz/+kCcs K7m5FPWhBjOWTlibNDx4y/lfsNGLegzEe8/X20tc= 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 5.15 156/567] bpf: Fix global subprog context argument resolution logic Date: Tue, 7 Mar 2023 17:58:12 +0100 Message-Id: <20230307165912.708019076@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307165905.838066027@linuxfoundation.org> References: <20230307165905.838066027@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 0c2fa93bd8d27..1f9369b677fe2 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -4468,6 +4468,7 @@ 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 */ @@ -4481,8 +4482,16 @@ 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