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 2A17733D6D8 for ; Wed, 18 Mar 2026 11:45:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773834349; cv=none; b=RbCTohi4yk6JyxKiEHkOPnNlHbaJeDlZZ2WefJX1f7L7QwqNITpyXNdgRwPoFRmztWVofqWH6Y+dAZH9RI7/kLp3VNSNWQndzR4bFoKppA6z5UbWfQ7GD6Z91Lc2S2tpjW+DPQlWjXnWVuBB3NSe32iDKup6fQLk/5NSRN8zArk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773834349; c=relaxed/simple; bh=cIluydrtyEjaIeM9IwO/I9477yuicTaZiy8Y6g4noCU=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=LgNOsBi+DamL9cb82mKVMKIVsKLOa/FP/K0DBkQAOxjpjxvdJxcqyFF4PvROxvphnMmNDGFGTsk+QQ880AqwDdgkMBbM9gSswjGaGsMfQ4ZvoWxwrwU3l3K1LkynwHdvG5l5QKhBkWDzbejXMpvMRMkTaLCWGiGLeuTLqLaYKTM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=J5ofoITu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="J5ofoITu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E647C19421; Wed, 18 Mar 2026 11:45:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773834348; bh=cIluydrtyEjaIeM9IwO/I9477yuicTaZiy8Y6g4noCU=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=J5ofoITuSkNn3JqDapPqmqfzKeHWHMVjXLtVqOylDdKpnkTZ0TKUgGdWXWrsSmFcG fixPAzXhql0KFpgrvxO8xwj63NZr59eHpveUsGHB0qargwSJGL5bWj5ZpXXwne95dx NM5mF6hrDPp6PmoCSzxZt9Zu3rdJxx71Zc41IxERUpLVR9kIWj9XSG/3rYVHz4Bx2x MzTI9Fv1NYYScYFDDEiUTXegvwB3OaEniW/O3dmQaib3B0phQslfiZ1jnQYx5cl5cy Mo6nV37y9JoEJaYXsVr8CSKSFlu45kQZQIyevdjNHhhrmzVc5TOzNPDHSn09HqVGZe 0X5MaaydN9MJA== From: Puranjay Mohan To: Kumar Kartikeya Dwivedi , bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Eduard Zingerman , Tejun Heo , Dan Schatzberg , kkd@meta.com, kernel-team@meta.com Subject: Re: [PATCH bpf-next v3 0/3] Allow variable offsets for syscall PTR_TO_CTX In-Reply-To: <20260318103526.2590079-1-memxor@gmail.com> References: <20260318103526.2590079-1-memxor@gmail.com> Date: Wed, 18 Mar 2026 11:45:28 +0000 Message-ID: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Kumar Kartikeya Dwivedi writes: > Enable pointer modification with variable offsets accumulated in the > register for PTR_TO_CTX for syscall programs where it won't be > rewritten, and the context is user-supplied and checked against the max > offset. See patches for details. Fixed offset support landed in [0]. > > By combining this set with [0], examples like the one below should > succeed verification now. > > SEC("syscall") > int prog(void *ctx) { > int *arr = ctx; > int i; > > bpf_for(i, 0, 100) > arr[i] *= i; > > return 0; > } > > [0]: https://lore.kernel.org/bpf/20260227005725.1247305-1-memxor@gmail.com > > Changelog: > ---------- > v2 -> v3 > v2: https://lore.kernel.org/bpf/20260318075133.1031781-1-memxor@gmail.com > > * Prevent arg_type for KF_ARG_PTR_TO_CTX from applying to other cases > due to preceding fallthrough. (Gemini/Sashiko) > > v1 -> v2 > v1: https://lore.kernel.org/bpf/20260317111850.2107846-2-memxor@gmail.com > > * Harden check_func_arg_reg_off check with ARG_PTR_TO_CTX. > * Add tests for unmodified ctx into tail calls. > * Squash unmodified ctx change into base commit. > * Add Reviewed-by's from Emil. > > Kumar Kartikeya Dwivedi (3): > bpf: Support variable offsets for syscall PTR_TO_CTX > selftests/bpf: Add syscall ctx variable offset tests > selftests/bpf: Test modified syscall ctx for ARG_PTR_TO_CTX > > kernel/bpf/verifier.c | 67 ++-- > .../selftests/bpf/prog_tests/verifier.c | 34 +- > .../selftests/bpf/progs/verifier_ctx.c | 356 +++++++++++++++--- > .../bpf/progs/verifier_global_subprogs.c | 95 ++++- > .../selftests/bpf/test_kmods/bpf_testmod.c | 2 +- > 5 files changed, 462 insertions(+), 92 deletions(-) > > > base-commit: 77378dabb50f593c756d393d8eacb0b91b758863 > -- > 2.52.0 Acked-by: Puranjay Mohan Thanks, Puranjay