| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <YbOMSUBRWAUFyDbQ@bombadil.infradead.org>
Date: Fri, 10 Dec 2021 09:20:09 -0800
From: Luis Chamberlain <mcgrof@...nel.org>
To: Xiaoming Ni <nixiaoming@...wei.com>
Cc: linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk,
ebiederm@...ssion.com, keescook@...omium.org, jlayton@...nel.org,
bfields@...ldses.org, yzaikin@...gle.com, apw@...onical.com,
joe@...ches.com, dwaipayanray1@...il.com, lukas.bulwahn@...il.com,
julia.lawall@...ia.fr, akpm@...ux-foundation.org,
wangle6@...wei.com
Subject: Re: [PATCH v2] sysctl: Add a group of macro functions to initcall
the sysctl table of each feature
On Fri, Dec 10, 2021 at 04:58:49PM +0800, Xiaoming Ni wrote:
> To avoid duplicated code, add a set of macro functions to initialize the
> sysctl table for each feature.
>
> The system initialization process is as follows:
>
> start_kernel () {
> ...
> /* init proc and sysctl base,
> * proc_root_init()-->proc_sys_init()-->sysctl_init_bases()
> */
> proc_root_init(); /* init proc and sysctl base */
> ...
> arch_call_rest_init();
> }
>
> arch_call_rest_init()-->rest_init()-->kernel_init()
> kernel_init() {
> ...
> kernel_init_freeable(); /* do all initcalls */
> ...
> do_sysctl_args(); /* Process the sysctl parameter: sysctl.*= */
> }
>
> kernel_init_freeable()--->do_basic_setup()-->do_initcalls()
> do_initcalls() {
> for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++) {
> do_initcall_level
> }
It was nice to have this documented in the commit log, however you
don't provide a developer documentation for this in your changes.
Can you justify through documentation why we can use init levels
with the above information for the sysctl_initcall() macro?
> The sysctl interface of each subfeature should be registered after
> sysctl_init_bases() and before do_sysctl_args().
Indeed.
> It seems
Seems is poor judgement for a change in the kernel. It is or not.
> that the sysctl
> interface does not depend on initcall_levels. To prevent the sysctl
> interface from being initialized before the feature itself. The
> lowest-level
Lower to me means early, but since we are talking about time, best
to clarify and say the latest init level during kernel bootup.
> late_initcall() is used as the common sysctl interface
> registration level.
>
> Signed-off-by: Xiaoming Ni <nixiaoming@...wei.com>
>
> ---
> v2:
> Add a simple checkpatch check.
> Add code comment.
> v1:
> https://lore.kernel.org/lkml/20211207011320.100102-1-nixiaoming@huawei.com/
> ---
> fs/coredump.c | 7 +------
> fs/dcache.c | 7 +------
> fs/exec.c | 8 +-------
> fs/file_table.c | 7 +------
> fs/inode.c | 7 +------
> fs/locks.c | 7 +------
> fs/namei.c | 8 +-------
> fs/namespace.c | 7 +------
> include/linux/sysctl.h | 19 +++++++++++++++++++
> kernel/stackleak.c | 7 +------
> scripts/checkpatch.pl | 6 ++++++
> 11 files changed, 34 insertions(+), 56 deletions(-)
>
> diff --git a/fs/coredump.c b/fs/coredump.c
> index 570d98398668..8f6c6322651d 100644
> --- a/fs/coredump.c
> +++ b/fs/coredump.c
> @@ -943,12 +943,7 @@ static struct ctl_table coredump_sysctls[] = {
> { }
> };
>
> -static int __init init_fs_coredump_sysctls(void)
> -{
> - register_sysctl_init("kernel", coredump_sysctls);
> - return 0;
> -}
> -fs_initcall(init_fs_coredump_sysctls);
> +kernel_sysctl_initcall(coredump_sysctls);
Nice.
Yes, although I went with fs_initcall() your documentation above
does give us certainty that this is fine as well. No need to kick
this through earlier.
> #endif /* CONFIG_SYSCTL */
>
> /*
> diff --git a/fs/dcache.c b/fs/dcache.c
> index 0eef1102f460..c1570243aaee 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -195,12 +195,7 @@ static struct ctl_table fs_dcache_sysctls[] = {
> { }
> };
>
> -static int __init init_fs_dcache_sysctls(void)
> -{
> - register_sysctl_init("fs", fs_dcache_sysctls);
> - return 0;
> -}
> -fs_initcall(init_fs_dcache_sysctls);
> +fs_sysctl_initcall(fs_dcache_sysctls);
Seems fine by me using the same logic as above and I like that
you are splitting this by bases. Likewise for the others, this
is looking good.
> diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
> index acf0805cf3a0..ce33e61a8287 100644
> --- a/include/linux/sysctl.h
> +++ b/include/linux/sysctl.h
> @@ -231,6 +231,25 @@ extern int sysctl_init_bases(void);
> extern void __register_sysctl_init(const char *path, struct ctl_table *table,
> const char *table_name);
Yes please take the time to write some documentation here which can
explain to developers *why* we use the init levels specified.
> #define register_sysctl_init(path, table) __register_sysctl_init(path, table, #table)
> +
> +#define sysctl_initcall(path, table) \
> + static int __init init_##table(void) \
> + { \
> + register_sysctl_init(path, table); \
> + return 0;\
> + } \
> + late_initcall(init_##table)
> +
> +/*
> + * Use xxx_sysctl_initcall() to initialize your sysctl interface unless you want
> + * to register the sysctl directory and share it with other features.
> + */
> +#define kernel_sysctl_initcall(table) sysctl_initcall("kernel", table)
> +#define fs_sysctl_initcall(table) sysctl_initcall("fs", table)
> +#define vm_sysctl_initcall(table) sysctl_initcall("vm", table)
> +#define debug_sysctl_initcall(table) sysctl_initcall("debug", table)
> +#define dev_sysctl_initcall(table) sysctl_initcall("dev", table)
> +
> extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
>
> void do_sysctl_args(void);
Luis
Powered by blists - more mailing lists