Messages in this thread Patch in this message | | | Date | Mon, 7 Feb 2022 14:27:28 +0100 | From | Domenico Andreoli <> | Subject | [PATCH] Fix regression due to "fs: move binfmt_misc sysctl to its own file" |
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Commit 3ba442d5331f did not go unnoticed, binfmt-support stopped to work on my Debian system since v5.17-rc2 (did not check with -rc1).
The existance of /proc/sys/fs/binfmt_misc is a precondition for attempting to mount the binfmt_misc fs, which in turn triggers the autoload of the binfmt_misc module. Without it, no module is loaded and no binfmt is available at boot.
Building as built-in or manually loading the module and mounting the fs works fine, it's therefore only a matter of interaction with user-space.
I could try to improve the Debian systemd configuration but I can't say anything about the other distributions.
In the meanwhile this patch restores a working system right after boot.
Fixes: 3ba442d5331f ("fs: move binfmt_misc sysctl to its own file") Signed-off-by: Domenico Andreoli <domenico.andreoli@linux.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Antti Palosaari <crope@iki.fi> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Clemens Ladisch <clemens@ladisch.de> Cc: David Airlie <airlied@linux.ie> Cc: Douglas Gilbert <dgilbert@interlog.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: James E.J. Bottomley <jejb@linux.ibm.com> Cc: Jan Kara <jack@suse.cz> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: John Ogness <john.ogness@linutronix.de> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Julia Lawall <julia.lawall@inria.fr> Cc: Kees Cook <keescook@chromium.org> Cc: Lukas Middendorf <kernel@tuxforce.de> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Mark Fasheh <mark@fasheh.com> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Phillip Potter <phil@philpotter.co.uk> Cc: Qing Wang <wangqing@vivo.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Sebastian Reichel <sre@kernel.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Stephen Kitt <steve@sk2.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Xiaoming Ni <nixiaoming@huawei.com>
--- fs/binfmt_misc.c | 6 +----- kernel/sysctl.c | 13 +++++++++++++ 2 files changed, 14 insertions(+), 5 deletions(-)
Index: b/fs/binfmt_misc.c =================================================================== --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -817,20 +817,16 @@ static struct file_system_type bm_fs_typ }; MODULE_ALIAS_FS("binfmt_misc"); -static struct ctl_table_header *binfmt_misc_header; - static int __init init_misc_binfmt(void) { int err = register_filesystem(&bm_fs_type); if (!err) insert_binfmt(&misc_format); - binfmt_misc_header = register_sysctl_mount_point("fs/binfmt_misc"); - return 0; + return err; } static void __exit exit_misc_binfmt(void) { - unregister_sysctl_table(binfmt_misc_header); unregister_binfmt(&misc_format); unregister_filesystem(&bm_fs_type); } Index: b/kernel/sysctl.c =================================================================== --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2806,6 +2806,17 @@ static struct ctl_table vm_table[] = { { } }; +static struct ctl_table fs_table[] = { +#if defined(CONFIG_BINFMT_MISC) || defined(CONFIG_BINFMT_MISC_MODULE) + { + .procname = "binfmt_misc", + .mode = 0555, + .child = sysctl_mount_point, + }, +#endif + { } +}; + static struct ctl_table debug_table[] = { #ifdef CONFIG_SYSCTL_EXCEPTION_TRACE { @@ -2825,6 +2836,7 @@ static struct ctl_table dev_table[] = { DECLARE_SYSCTL_BASE(kernel, kern_table); DECLARE_SYSCTL_BASE(vm, vm_table); +DECLARE_SYSCTL_BASE(fs, fs_table); DECLARE_SYSCTL_BASE(debug, debug_table); DECLARE_SYSCTL_BASE(dev, dev_table); @@ -2832,6 +2844,7 @@ int __init sysctl_init_bases(void) { register_sysctl_base(kernel); register_sysctl_base(vm); + register_sysctl_base(fs); register_sysctl_base(debug); register_sysctl_base(dev);
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