From patchwork Thu Apr 18 01:07:13 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Edward Liaw X-Patchwork-Id: 13634037 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-pg1-f201.google.com (mail-pg1-f201.google.com [209.85.215.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CAECA4F889 for ; Thu, 18 Apr 2024 01:07:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713402463; cv=none; b=Ud+gx5wuVMdl4Jo7vhPI/CCyi3Omwv29z05GWtc65cPxMPCNzbpe+zD7FnV3Z07o+MxjOWH3gPl0GITlc+DGDn8lLjlR03fML/ZLOtYmyds6XTLV4wbnQfoNTS35zCqia8G/sX7BZRj2JbhHp6kZySdoN3j6y1qlZ4OGeme8TDU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713402463; c=relaxed/simple; bh=Gy+v3kHc6gUJFOVz0cecKLWhrUu0SiEkWzcElEXVN2Y=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=H/obESEkwbgKpy1yWCwMYOnXdH8Gt2TIexuLcNYAcWLPq+gHQDJrIv7/g+Gk/eD10fJ0zb/M05CwMvwDYxUg0k/yHo3huuAXHonADmkJqeUWc5AhNoMsRixFCP9Uq5w1fNEOLbNvNR60EEey8M9LgmNu6KCguLfGmr59jNbaBfQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--edliaw.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=nKy8Ip0E; arc=none smtp.client-ip=209.85.215.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--edliaw.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="nKy8Ip0E" Received: by mail-pg1-f201.google.com with SMTP id 41be03b00d2f7-5e4df21f22dso335255a12.0 for ; Wed, 17 Apr 2024 18:07:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1713402460; x=1714007260; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=Cs92mryat0OzgsnGDmpmqjunv7BtT58JcaK8X9mxrOg=; b=nKy8Ip0EpUHHR27Yj3g3IcfwKxkfDi7O+ooHXdM1g6ytEgen15I5dJR0O/jgjBzoHT fi3d0eiQYrd68/zAlfQcIV52wCh7Y+Lu32OOvI9DDmIk6di1/z9WQzMJFhN8p+nC1z14 nxvXyeQ9iPRYbiM+xmLhwiINykmY1wcSgqmcDllZgId+2JS8J7c7P/A6gah4VPcsq2PN HioRhwgGggI1ZI02IAOJY88wfqER4gdYgA7gHSn0XVkmvIyRU0qVxS8xHPJuE8nGrBYJ vRWxB5iAx24Fdw6adqBKZ/rF9+omauuJHF7Bsz7TUEUoSBCjItdOoQTkL27pPuZde8qv zlMQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1713402460; x=1714007260; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Cs92mryat0OzgsnGDmpmqjunv7BtT58JcaK8X9mxrOg=; b=IdV6Ckiw4Tax7h/6pvPy0toKY2pD4ueRO/p48qbbpO/G2+JpjaEKkc0IscccbQOXeV HmmdSsl2927ebgDr2vH4KrdQfsGzuuat1L1zVyAvaOvyDcnr/neR93YkqfYDTVxikDq0 80vja+Fyh7P5XedmfucFNMTv5uMMs+JkyQtlxGXMGY09VJ6BPpit8Oe3YFMi4iAkakrq zlz25HO57W4NiAXsWmg1+PpWYRSBwNUWGhspLhU2tVeaPqorj2TsVqMFzZpuV4tgUHKX MMcYTupdIouISya4PdKehqc+GfkO3BHns8spjtwkClyzNaNJlH1PeMaqwRctYbuuc+NY ONQw== X-Gm-Message-State: AOJu0Yw6wDCXjAe5ez26+Mv09s03klrUO5i8WHQgAbCpZWF4gATNFa18 MswobYOXEyU77kx7ztG+47o1zv2uQviqNEovKRk7xlapAeRFDSLd/ZAZyUQ1pjFLL6Jd7VfJ+Dh WQA== X-Google-Smtp-Source: AGHT+IHJxc7eNFka5oLm+urHCgHJgtjUp/kG6lLtOsi7pjI5NnoubZUAgtsoYBT/QXLuYw7ioKAL5C8eHnk= X-Received: from edliaw.c.googlers.com ([fda3:e722:ac3:cc00:24:72f4:c0a8:305d]) (user=edliaw job=sendgmr) by 2002:a63:af54:0:b0:5e8:65ae:1142 with SMTP id s20-20020a63af54000000b005e865ae1142mr3079pgo.4.1713402459921; Wed, 17 Apr 2024 18:07:39 -0700 (PDT) Date: Thu, 18 Apr 2024 01:07:13 +0000 In-Reply-To: <20240418010723.3069001-1-edliaw@google.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <16430256912363@kroah.com> <20240418010723.3069001-1-edliaw@google.com> X-Mailer: git-send-email 2.44.0.769.g3c40516874-goog Message-ID: <20240418010723.3069001-5-edliaw@google.com> Subject: [PATCH 5.15.y v2 4/5] bpf: Fix out of bounds access for ringbuf helpers From: Edward Liaw To: stable@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Hao Luo Cc: bpf@vger.kernel.org, kernel-team@android.com, Edward Liaw , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, tr3e.wang@gmail.com X-Patchwork-Delegate: bpf@iogearbox.net From: Daniel Borkmann Both bpf_ringbuf_submit() and bpf_ringbuf_discard() have ARG_PTR_TO_ALLOC_MEM in their bpf_func_proto definition as their first argument. They both expect the result from a prior bpf_ringbuf_reserve() call which has a return type of RET_PTR_TO_ALLOC_MEM_OR_NULL. Meaning, after a NULL check in the code, the verifier will promote the register type in the non-NULL branch to a PTR_TO_MEM and in the NULL branch to a known zero scalar. Generally, pointer arithmetic on PTR_TO_MEM is allowed, so the latter could have an offset. The ARG_PTR_TO_ALLOC_MEM expects a PTR_TO_MEM register type. However, the non- zero result from bpf_ringbuf_reserve() must be fed into either bpf_ringbuf_submit() or bpf_ringbuf_discard() but with the original offset given it will then read out the struct bpf_ringbuf_hdr mapping. The verifier missed to enforce a zero offset, so that out of bounds access can be triggered which could be used to escalate privileges if unprivileged BPF was enabled (disabled by default in kernel). Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it") Reported-by: (SecCoder Security Lab) Signed-off-by: Daniel Borkmann Acked-by: John Fastabend Acked-by: Alexei Starovoitov (cherry picked from commit 64620e0a1e712a778095bd35cbb277dc2259281f) Signed-off-by: Edward Liaw --- kernel/bpf/verifier.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 14813fbebc9f..3dfc45ed428a 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5153,9 +5153,15 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, case PTR_TO_BUF: case PTR_TO_BUF | MEM_RDONLY: case PTR_TO_STACK: + /* Some of the argument types nevertheless require a + * zero register offset. + */ + if (arg_type == ARG_PTR_TO_ALLOC_MEM) + goto force_off_check; break; /* All the rest must be rejected: */ default: +force_off_check: err = __check_ptr_off_reg(env, reg, regno, type == PTR_TO_BTF_ID); if (err < 0)