From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-173.mta0.migadu.com (out-173.mta0.migadu.com [91.218.175.173]) (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 94F543FFAC9 for ; Mon, 2 Mar 2026 15:05:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772463906; cv=none; b=AuzbGr2wPD3Dn7qNkr5N8/JloGCR58GJSKZsuAi8K1fxXzZh619BJFMYexkXAACXiqQjZg6Nj1aGS9QZfwBciw0VAdMWttnRqKAT1owIuywKAG7MK+4ia8TZkb74DNhzwY4t8j2SZKvUvRG8AVdlSZ8jHO78l/YEXPCFjPVS9/Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772463906; c=relaxed/simple; bh=g8iFQt8PutO9ez9QZhPdi2ZlJazN1/pZxoozXBn3C6Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=baoWRvYuVdbz8UtfwITHZtIHdv0GcoC90jKN9/sUIdOQ8YjInuKCDgkkuJ4gFw28rsk8cQuB5kB0UxH92Q7PHmrBGc0Fx4aI2WdCKFObDh1ffoL9j8lRQtsFYNDHlYLRaNG7UCR2jBNQHYbDBFDLFIlpdsTsGEmlNaoNz9DObUw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=LtiQJZDB; arc=none smtp.client-ip=91.218.175.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="LtiQJZDB" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1772463901; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=P+PWWkwazjgxzegEXu2v7YMpb7U2FHOXq8Nh1mdAOFE=; b=LtiQJZDBVu1SJwdRRouZ70fq6wxNk92yLmHsbbZ+531nmHWqAS5Vuy9FtkOVQq/fEJPjt/ GvdbEkqNLGv0ovEBqlw88Tu+fPMfKPVIqxoGA4h3/LjH9oIJsxylPoQpvVV/rueIIauCIe lilecwkNCo6/TixA2a9GJJoCvK9HMVs= From: Leon Hwang To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan , Feng Yang , Leon Hwang , Menglong Dong , Puranjay Mohan , =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , Pu Lehui , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, netdev@vger.kernel.org, kernel-patches-bot@fb.com Subject: [PATCH bpf-next v2 4/6] bpf: Disallow !call_get_func_ip progs tail-calling call_get_func_ip progs Date: Mon, 2 Mar 2026 23:03:40 +0800 Message-ID: <20260302150342.55709-5-leon.hwang@linux.dev> In-Reply-To: <20260302150342.55709-1-leon.hwang@linux.dev> References: <20260302150342.55709-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Trampoline-based tracing programs that call bpf_get_func_ip() rely on the func IP stored on the stack. Mixing !call_get_func_ip progs with call_get_func_ip progs via tail calls could break this assumption. To address this, reject the combination of !call_get_func_ip progs with call_get_func_ip progs in bpf_map_owner_matches(), which prevents the tail callee from getting a bogus func IP. Also reject call_get_func_ip mismatches during initialization to prevent bypassing the above restriction. Without this check, the above restriction can be bypassed as follows. struct { __uint(type, BPF_MAP_TYPE_PROG_ARRAY); __uint(max_entries, 1); __uint(key_size, sizeof(__u32)); __uint(value_size, sizeof(__u32)); } jmp_table SEC(".maps"); SEC("?fentry") int BPF_PROG(prog_a) { bpf_printk("FUNC IP: 0x%llx\n", bpf_get_func_ip()); bpf_tail_call_static(ctx, &jmp_table, 0); return 0; } SEC("?fentry") int BPF_PROG(prog_b) { bpf_tail_call_static(ctx, &jmp_table, 0); return 0; } The jmp_table is shared between prog_a and prog_b. * Load prog_a first. At this point, owner->call_get_func_ip=true. * Load prog_b next. At this point, prog_b passes the compatibility check. * Add prog_a to jmp_table. * Attach prog_b to a kernel function. When the kernel function runs, prog_a will get a bogus func IP because no func IP is prepared on the trampoline stack. Fixes: 1e37392cccde ("bpf: Enable BPF_TRAMP_F_IP_ARG for trampolines with call_get_func_ip") Signed-off-by: Leon Hwang --- include/linux/bpf.h | 1 + kernel/bpf/core.c | 7 +++++++ 2 files changed, 8 insertions(+) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index dbafed52b2ba..fb978650b169 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -289,6 +289,7 @@ struct bpf_map_owner { u32 xdp_has_frags:1; u32 sleepable:1; u32 kprobe_write_ctx:1; + u32 call_get_func_ip:1; u64 storage_cookie[MAX_BPF_CGROUP_STORAGE_TYPE]; const struct btf_type *attach_func_proto; enum bpf_attach_type expected_attach_type; diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 121a697d4da5..1b88878fe5c5 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2391,6 +2391,7 @@ static void bpf_map_owner_init(struct bpf_map_owner *owner, const struct bpf_pro owner->xdp_has_frags = aux->xdp_has_frags; owner->sleepable = fp->sleepable; owner->kprobe_write_ctx = aux->kprobe_write_ctx; + owner->call_get_func_ip = fp->call_get_func_ip; owner->expected_attach_type = fp->expected_attach_type; owner->attach_func_proto = aux->attach_func_proto; for_each_cgroup_storage_type(i) @@ -2422,11 +2423,17 @@ static bool bpf_map_owner_matches(const struct bpf_map *map, const struct bpf_pr case BPF_MAP_OWNER_MATCH_FOR_INIT: if (owner->kprobe_write_ctx != aux->kprobe_write_ctx) return false; + if (owner->call_get_func_ip != fp->call_get_func_ip) + return false; break; case BPF_MAP_OWNER_MATCH_FOR_UPDATE: if (!owner->kprobe_write_ctx && aux->kprobe_write_ctx) return false; + if (bpf_prog_has_trampoline(fp)) { + if (!owner->call_get_func_ip && fp->call_get_func_ip) + return false; + } break; } -- 2.52.0