From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f45.google.com (mail-wm1-f45.google.com [209.85.128.45]) (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 D333B3ECBEE for ; Mon, 25 May 2026 16:19:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.45 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779725966; cv=none; b=i0dTvQiMwNyVjOUg7iwUglkpfc595lpd2O6xM/EAc2CpHzAP8e5n23qd7obYwGnlyWT/1AtJ52ElZ9WpyeIfM9pbwexvEFkCydtdtbyPV1M9Dd2xd6bkCpE5xwwmXl5l2Lvd8l2lRxPTP69CRWWmkQ4zFMTpZiWj0mOizVl25ek= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779725966; c=relaxed/simple; bh=6ATTepTt/W1eTfJKlZcOEC7miXlLa4M2ScAL84EJqWk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gXUhZHWLHk2/u/by+xDb4WlrlZInXUlvpMgBQKosWOnGB2pdueiDOAPQRSnf4WQkhTBL2QKbBx73supZErMuSdzXRb7rArKDXZvCFsZdGzv33LA7Ikd2sIxmhO6r+BCvLgqeIYTsOZxheAgezpoadRf+BIV1dKI9jNYquSNLtl4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=dr4TZWgD; arc=none smtp.client-ip=209.85.128.45 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="dr4TZWgD" Received: by mail-wm1-f45.google.com with SMTP id 5b1f17b1804b1-48fde648a71so63301355e9.0 for ; Mon, 25 May 2026 09:19:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1779725963; x=1780330763; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=6YA+/JJXQ9abERc/NViF0XyaL5qdJ2pUb4chRkVwshY=; b=dr4TZWgD1Esm3Qat2phkFsMogL1QSisy0KS5zRNj7QLd+O/GTWfZKF/uEdi+t9nmcR dNii4QQxToJf+zI9chidglTAOXLiVdJ387YJpWnu4O63RZWZpdft6OjU//0zfSVBO/Yy aLoJ+GdqYyIcf1QZ3S/llKFAOlJ84UyYM98oHjPHgYY3F7FL0OrljqOzg8++8jmqQw7A O5n5KKQspBxCRl24VEYndxfcbPND9j7SmWztWHYdSuVM/njdzkK1jbGeu/q+wYu+k1tw 8TTcdzkzuBj6AUmwdDxqdavz+slVMsWbwdX+qKe1b1YYNz7v1oMCb8aIIpb7FBEk2qd1 WQkg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779725963; x=1780330763; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=6YA+/JJXQ9abERc/NViF0XyaL5qdJ2pUb4chRkVwshY=; b=g7Yc7Kw0o5u9ghABF6klmBcfXwFjzKdkXCxpLxPbxambL6/IpomJBSe/4dl9DwPQUw 4QIT6Uz+cywFFmut2rjWiJmrMF7lrGPEjBqraU6kcGuwXqmVZxYin1XqFBSXMjjWkeZp zQSh/JWQ3ua+ESflnQN6q7bTVSyNFCvE9Ujx5+hYO0a3JMJlm0IiIUk/Ij+fVwgiYXZY Uj/hrreX3eMIqRKqn8luy2cvolV52f+nzsaap5tdOq9oYgOIFfNk9xXsBWiLIlsaa4US xL/DXgog/I2TkOOJcC0XHJZkSiCQZIrw+FK7Q+Jl3rgRV1mISWuBzBn0wlgHB1BCFOCl SLfw== X-Forwarded-Encrypted: i=1; AFNElJ+/nCa7VeKFvso2qGBRge6eGdxThDjLTmHhwFCj8K9LEChEJKirk1QrL8s6Pjzxxsghy/4=@vger.kernel.org X-Gm-Message-State: AOJu0Yyz9WIaz2589v9qJCGbHRoSRRS8+w47YIDQhuITeKr2/s7qb2L5 4O4U1pzugXgaEycK1Vta/hA2lD6WGCMicJIrwsJMlu2MTGb3ur/0DGu0OepADO50OfU= X-Gm-Gg: Acq92OF/SKwYQACDVaGjB9JlJLLoE1rpa4/I46TCTTn+Lii33ylAstVCBn2NbRZD71U VwCPpm1tqyxz5PGuZiIa1anc8IRVyoP64oU5T4/p8rgGlLLvD2lLdJfBKESQ7ZZy2QIsWIKelht OwqdmmuQp5T8FMkbHWfhwRxdnBAd2WySBOIndtJngxD6vF390/69W4Gu6msX3Q920uAGyo4c42c kgJ0D7cv7kHMMcmW1otmwKQFBuEE4eliUGioxEAXAlB4rctuT6InKB3v6i/abgVRzaK8nfrzjnq 4JQcyM45JGI+7JfQRGiJq/VeR6Xa3V8IAuRWAPQm/to77hfastsk6h5NxL/LVD78urLKSL0+ijS Tb5cSRBFTzJN5lyckrXgmafWY3IO/xJjb7KXeb9XKRrIDxq3OOZfS3ixp13JFamKLhgTQ28WQ6H y4LKFF4aHzuLYDTfnI+2+Zx27X3rgUBTAWHjORMLg6sj+E5LoIkYYSpzhO7hJ7XjFNh0L89hd3C tVeoupgma6iFnE7xK5ejo6seI0y3dX9JmswOj5dVu9wc4vPd9q7OvAagqDGGj3K/vu/XQ== X-Received: by 2002:a05:600c:3b07:b0:490:f7c:b19 with SMTP id 5b1f17b1804b1-490420f67f5mr197977845e9.0.1779725963153; Mon, 25 May 2026 09:19:23 -0700 (PDT) Received: from ?IPV6:2a00:1028:838d:271e:8e3b:4aff:fe4c:a100? (dynamic-2a00-1028-838d-271e-8e3b-4aff-fe4c-a100.ipv6.o2.cz. [2a00:1028:838d:271e:8e3b:4aff:fe4c:a100]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49059cc9a91sm48939425e9.1.2026.05.25.09.19.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 May 2026 09:19:22 -0700 (PDT) Message-ID: Date: Mon, 25 May 2026 18:19:19 +0200 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 06/11] moduleparam: Add seq_buf-based .get callback alongside .get_str To: Kees Cook Cc: Luis Chamberlain , Pengpeng Hou , Richard Weinberger , Anton Ivanov , Johannes Berg , "Rafael J. Wysocki" , Len Brown , Corey Minyard , Gabriel Somlo , "Michael S. Tsirkin" , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Simona Vetter , Bart Van Assche , Jason Gunthorpe , Leon Romanovsky , Laurent Pinchart , Hans de Goede , Mauro Carvalho Chehab , Bjorn Helgaas , Hannes Reinecke , "James E.J. Bottomley" , "Martin K. Petersen" , Daniel Lezcano , Zhang Rui , Lukasz Luba , Greg Kroah-Hartman , Jiri Slaby , Alan Stern , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Jason Baron , Jim Cromie , Tiwei Bie , Benjamin Berg , =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= , "David E. Box" , "Maciej W. Rozycki" , Srinivas Pandruvada , Peter Zijlstra , Heiko Carstens , Vasily Gorbik , Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Vinod Koul , Frank Li , Daniel Gomez , Sami Tolvanen , Aaron Tomlin , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Andrew Morton , John Johansen , Paul Moore , James Morris , "Serge E. Hallyn" , Andy Shevchenko , Georgia Garcia , kvm@vger.kernel.org, dmaengine@vger.kernel.org, linux-modules@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, apparmor@lists.ubuntu.com, linux-security-module@vger.kernel.org, linux-um@lists.infradead.org, linux-acpi@vger.kernel.org, openipmi-developer@lists.sourceforge.net, qemu-devel@nongnu.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, linux-pci@vger.kernel.org, linux-scsi@vger.kernel.org, linux-pm@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, usb-storage@lists.one-eyed-alien.net, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-hardening@vger.kernel.org References: <20260521133315.work.845-kees@kernel.org> <20260521133326.2465264-6-kees@kernel.org> Content-Language: en-US From: Petr Pavlu In-Reply-To: <20260521133326.2465264-6-kees@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/21/26 3:33 PM, Kees Cook wrote: > Add a new struct kernel_param_ops::get callback whose signature > takes a struct seq_buf instead of a raw char buffer: > > int (*get)(struct seq_buf *sb, const struct kernel_param *kp); > > The previously-legacy .get field is now .get_str (char *buffer); > .get is the new seq_buf-aware form. param_attr_show() prefers .get > when set, otherwise falls back to .get_str. WARN_ON_ONCE() if both > are set. Return contract for .get: > > < 0 : errno propagated to userspace; seq_buf contents discarded > = 0 : success; length derived from seq_buf_used() > > 0 : forbidden; the dispatcher WARN_ON_ONCE()s and treats as 0 > > The default policy on seq_buf_has_overflowed() is silent truncation, > matching scnprintf()/sysfs_emit() behaviour. Callbacks that want a > specific overflow errno can check seq_buf_has_overflowed() and > return their preferred error. > > No callbacks use .get yet; the legacy path is still the only one in use > after this commit. A subsequent commit teaches DEFINE_KERNEL_PARAM_OPS > to route initializers by type. > > Signed-off-by: Kees Cook Reviewed-by: Petr Pavlu -- Petr