From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) (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 A2AB23CEB99; Wed, 19 Aug 2026 18:15:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.97.179.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787163362; cv=none; b=YurhwXLgyGnCx12C4vHn17j/xvW9GYCwkjlFy+dMo4kcryl9Eo3LY6ddHeSeQ33obcUvPaXxT3/6QsZHnAc+58qW0tNvgEbW9KEZFaWpeSlb97YW5QBDG5JF7cZPZwXVXqp1CHX5ef5zVVOGt/7jAHo/Z2ZJdu6rZGvTjpl5Qd4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787163362; c=relaxed/simple; bh=hxty/hn4eltm6C0Y4EZQnHbws7rSxIFBmMOEDEavcn4=; h=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc; b=ugTBPWmn6bPhWtL10mP0QU1x35L1uU195HfhaImiPwHumpOWfEePfEWLsU4Z+7OnUMqT0L0wkgJT6cOUnCDWZxUXm81VLNcZwF9YAW6TCc0+slMdgM3D1jmeE2nUFIGzFZDiq89qohnSmTI5s7ZMGx429R3IgWS2pHVT06KwoLs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=j6B0Jy5s; arc=none smtp.client-ip=213.97.179.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="j6B0Jy5s" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Cc:To:Content-Transfer-Encoding:Content-Type:MIME-Version: Message-Id:Date:Subject:From:From:Reply-To; bh=fdQkiyp3Qsqh2GCyFxM5saepTDceNMzdb1x19L1bJys=; b=j6B0Jy5s0l1rIqoAIFUFYRNw0A O8zrKTcRNqYe8rdyon/tzyD/f+r40qZQ7xbPPGamCanY/2lKECgUFlsAbWuIiWsKJ1uNL7wtKRWk+ cPXGDEGxS3HvolMLPzNOY28Kvn6oRBQCJdkcQsttJeBjiMHhNAR5TCc275oy7UBPYFoxzvLCb2dsT s+0Bni82WNohP8aBWozbNZO3ullR3nDwaNzrKvoTnob3s/xCOxd7ENU0zSyAh33ApHNg5CrkT0jyW tx4C8qWCUjFsSc/ZqPM+8Cf3aly39EwR7qsWIcA1xwW4acnjRr5lLTbFLnksh8HBG1pzPaVoHK1Nr wEee9tBw==; Received: from 186-249-147-181.shared.desktop.com.br ([186.249.147.181] helo=[127.0.1.1]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1wwkpH-006ENH-4M; Wed, 19 Aug 2026 20:15:47 +0200 From: Mauricio Faria de Oliveira Subject: [PATCH RFC v3 00/13] sysctl: add module aliases Date: Wed, 19 Aug 2026 15:16:13 -0300 Message-Id: <20260819-sysctl-module-aliases-v3-0-aab90569365d@igalia.com> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAO3yhWoC/4WNQQqDMBBFryKzbkqSosauhEIP0G1xEc2oA2pKx kpFvHtTL9Dl/4///gaMgZDhmmwQcCEmP8VwOSXQ9HbqUJCLGbTUmTTKCF65mQcxevceUNiBLCM L3aZGqlphnSuI21fAlj6H9wmP+w2qWPbEsw/r8bXoA/3RLlpI4VKbFc5imhempO7Hzo0fodr3/ QtVQJ5iwAAAAA== X-Change-ID: 20260818-sysctl-module-aliases-2f5801b1eb71 To: Kees Cook , Joel Granados , Nathan Chancellor , Nicolas Schier , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman Cc: kernel-dev@igalia.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, fsverity@lists.linux.dev, keyrings@vger.kernel.org, bpf@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kbuild@vger.kernel.org, netdev@vger.kernel.org, linux-wpan@vger.kernel.org, lvs-devel@vger.kernel.org, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, linux-sctp@vger.kernel.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, bridge@lists.linux.dev, mptcp@lists.linux.dev, rds-devel@oss.oracle.com, virtualization@lists.linux.dev, Mauricio Faria de Oliveira X-Mailer: b4 0.14.2 This series adds 'sysctl:' aliases to modules that register sysctl tables; e.g.: $ modinfo ./mpls_router.ko | grep sysctl: alias: sysctl:*/net/mpls/conf/*/input alias: sysctl:*/net/mpls/default_ttl alias: sysctl:*/net/mpls/ip_ttl_propagate alias: sysctl:*/net/mpls/platform_labels It provides a trivial way to map /proc/sys files to modules (not trivial today), and for userspace to handle nonexistent /proc/sys files (e.g., procps's sysctl and systemd-sysctl applying tunables) with "modprobe sysctl:<...>" and a retry. This is done almost automatically with register_sysctl(), register_net_sysctl() and friends as wrappers of MODULE_SYSCTL_TABLE (similar to MODULE_DEVICE_TABLE), which emits symbols for file2alias/modpost to find and parse the sysctl tables. The big exception to 'almost' are sysctl tables and paths allocated or defined at runtime (e.g., per-namespace or per-device), as all information is required at build-time. Fortunately, such tables and paths are often based on 'templates' which are static and can be used. This is done by plumbing the template table/path as optional arguments (macros with default values as default_gfp()), so not to create functions for all cases: register_sysctl(path, table [, table_tmpl [, path_tmpl]]); register_net_sysctl(net, path, table [, table_tmpl[, path_tmpl]]); register_net_sysctl_sz(net, path, table, size [, table_tmpl[, path_tmpl]]); In this series: - Patch 1 prevents a build error later. - Patch 2 adds CONFIG_SYSCTL_MODULE_ALIASES. - Patch 3 adds MODULE_SYSCTL_TABLE(). - Patches 4-5 add register_sysctl() wrapper and update some callers. - Patches 6-10 add register_net_sysctl[_sz]() wrappers and update some callers. - Patches 11-13 add file2alias support. Not all maintainers/reviewers (specially for the many changes in net/) are in To/Cc in respect of their time, as this RFC probably needs more general and earlier feedback before settling on specific changes for their review. All lists are included for visibility, though. Example ======= To put it all together, 'mpls_router.ko' (used above) from 'net/mpls/af_mpls.c': - Tables: static const struct ctl_table mpls_table[] = { { .procname = "platform_labels", ... .procname = "ip_ttl_propagate", ... .procname = "default_ttl", }, }; static const struct ctl_table mpls_dev_table[] = { { .procname = "input", ... }, }; - Registration: net->mpls.ctl = register_net_sysctl_sz(net, "net/mpls", table, table_size, mpls_table); #define path_template "net/mpls/conf/%s" ... mdev->sysctl = register_net_sysctl_sz(net, path, table, table_size, mpls_dev_table, path_template); - Symbols: $ objdump -t net/mpls/mpls_router.ko \ | grep '__mod_device_table__.*__sysctl__' 0000000000000900 l O .data 0000000000000018 __mod_device_table__kmod_mpls_router__sysctl__mpls_table.177 0000000000000940 l O .data 0000000000000018 __mod_device_table__kmod_mpls_router__sysctl__mpls_dev_table.174 - file2alias: $ grep '^MODULE_ALIAS("sysctl:' net/mpls/mpls_router.mod.c MODULE_ALIAS("sysctl:*/net/mpls/platform_labels"); MODULE_ALIAS("sysctl:*/net/mpls/ip_ttl_propagate"); MODULE_ALIAS("sysctl:*/net/mpls/default_ttl"); MODULE_ALIAS("sysctl:*/net/mpls/conf/*/input"); - modinfo: $ modinfo ./mpls_router.ko | grep sysctl: alias: sysctl:*/net/mpls/conf/*/input alias: sysctl:*/net/mpls/default_ttl alias: sysctl:*/net/mpls/ip_ttl_propagate alias: sysctl:*/net/mpls/platform_labels Testing ======= Configurations: - allmodconfig with the option enabled (check for 'MODULE_ALIAS("sysctl:' lines) - allmodconfig with the option disabled (check for code errors) - allyesconfig with the option enabled (check for include errors) Architectures (test different bitness, endianness, and ELF handling) - x86_64, i386 - arm, arm64 - arc - alpha - loongarch - m68k - mips(64)(el) - parisc(64) - powerpc(64(le)) - riscv - sparc64 - s390 The resulting '.mod.c' files of allmodconfig with the option enabled was checked for consistency across all architectures, and that the new aliases lines are the difference to allmodconfig with the option disabled. Disabling ========= - Per-call: Use 'register_sysctl_sz()' or '__register_net_sysctl_sz()' directly. - Per-file: Use '#define SYSCTL_MODULE_ALIASES_DISABLE'. - System-wide: Maybe something along these lines: # cat /etc/modprobe.d/no-sysctl.conf alias sysctl:* no-sysctl install no-sysctl /bin/false # modinfo -F name sysctl:/proc/net/mpls/default_ttl mpls_router # modprobe sysctl:/proc/net/mpls/default_ttl modprobe: ERROR: Error running install command '/bin/false' for module no_sysctl: retcode 1 modprobe: ERROR: could not insert 'no_sysctl': Invalid argument P.S. ==== I wrote proof-of-concept patches for procps sysctl and systemd-sysctl some time ago, which worked as expected, i.e., successfully set sysctl tunables which did not exist in /proc/sys, by running 'modprobe sysctl:/proc/sys/...' and retrying. Should this series eventually be merged, the patches will be submitted upstream as well, for userspace to start consuming it. Signed-off-by: Mauricio Faria de Oliveira Changes in v3: - All issues were reported by sashiko-bot@kernel.org. - Tested allmodconfig with option enabled on x86_64. - Patch 2: - Fix typo ('s/options/option/'). - Patch 3: - Fix usage of __UNIQUE_ID(). - Add __must_be_array() in MODULE_SYSCTL_TABLE(). - Patch 4: - Remove trailing backslash in register_sysctl(). - Patch 6: - Fix missing __register_net_sysctl_sz() in !CONFIG_SYSCTL. - Patch 13: - Fix potential out-of-bounds read in do_sysctl_entry(). - Add check for entry size of zero. - Link to v2: https://lore.kernel.org/r/20260818-sysctl-module-aliases-v2-0-d5a69dae5798@igalia.com Changes in v2: - This is based on the series submitted 4 years ago, with Originally-by: tags added in related patches. - Link to v1: https://lore.kernel.org/linux-fsdevel/20220722022416.137548-1-mfo@canonical.com/ --- Mauricio Faria de Oliveira (13): keys, pidns, fs/verity, riscv/vector: reorder '#include ' proc: add config option SYSCTL_MODULE_ALIASES sysctl, mod_devicetable: add macro MODULE_SYSCTL_TABLE sysctl: add register_sysctl() wrapper for MODULE_SYSCTL_TABLE sysctl, parport: update register_sysctl() callers with template arguments sysctl, net: add register_net_sysctl{_sz}() wrappers for MODULE_SYSCTL_TABLE sysctl, net: update register_net_sysctl{_sz}() callers with template arguments sysctl, net: update register_net_sysctl_sz(ARRAY_SIZE(table_tmpl)) with template arguments sysctl, ipv6: update register_net_sysctl{_sz}() callers with template arguments sysctl, net: update register_net_sysctl_sz() edge case sysctl: unrandomize struct ctl_table.procname modpost: move addend_*_rel() calls into addend_rel() modpost: handle MODULE_SYSCTL_TABLE symbols arch/riscv/kernel/vector.c | 1 + drivers/net/vrf.c | 3 +- drivers/parport/procfs.c | 26 +++- fs/proc/Kconfig | 13 ++ fs/verity/init.c | 1 + include/linux/key.h | 1 - include/linux/mod_devicetable.h | 7 + include/linux/pid_namespace.h | 1 + include/linux/sysctl.h | 110 ++++++++++++++- include/net/ipv6.h | 6 +- include/net/net_namespace.h | 47 ++++++- net/bridge/br_netfilter_hooks.c | 3 +- net/core/neighbour.c | 11 +- net/core/sysctl_net_core.c | 3 +- net/ieee802154/6lowpan/reassembly.c | 2 +- net/ipv4/devinet.c | 12 +- net/ipv4/ip_fragment.c | 3 +- net/ipv4/route.c | 3 +- net/ipv4/sysctl_net_ipv4.c | 2 +- net/ipv4/xfrm4_policy.c | 3 +- net/ipv6/addrconf.c | 7 +- net/ipv6/icmp.c | 6 +- net/ipv6/netfilter/nf_conntrack_reasm.c | 4 +- net/ipv6/reassembly.c | 3 +- net/ipv6/route.c | 10 +- net/ipv6/sysctl_net_ipv6.c | 13 +- net/ipv6/xfrm6_policy.c | 3 +- net/mpls/af_mpls.c | 9 +- net/mptcp/ctrl.c | 3 +- net/netfilter/ipvs/ip_vs_ctl.c | 4 +- net/netfilter/ipvs/ip_vs_lblc.c | 3 +- net/netfilter/ipvs/ip_vs_lblcr.c | 3 +- net/netfilter/nf_conntrack_standalone.c | 5 +- net/netfilter/nf_log.c | 9 +- net/rds/tcp.c | 4 +- net/sctp/sysctl.c | 3 +- net/smc/smc_sysctl.c | 2 +- net/sysctl_net.c | 10 +- net/unix/sysctl_net_unix.c | 3 +- net/vmw_vsock/af_vsock.c | 4 +- net/xfrm/xfrm_sysctl.c | 2 +- scripts/mod/devicetable-offsets.c | 6 + scripts/mod/file2alias.c | 237 ++++++++++++++++++++++++++++++++ scripts/mod/modpost.c | 46 ++++--- scripts/mod/modpost.h | 25 ++++ 45 files changed, 575 insertions(+), 107 deletions(-) --- base-commit: 2697ef8943c9985c14708a6429e21812693857b2 change-id: 20260818-sysctl-module-aliases-2f5801b1eb71 Best regards, -- Mauricio Faria de Oliveira