From: Kees Cook <keescook@chromium.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Luis Chamberlain <mcgrof@kernel.org>,
Iurii Zaikin <yzaikin@google.com>,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
linux-mm@kvack.org, Ivan Teterevkov <ivan.teterevkov@nutanix.com>,
Michal Hocko <mhocko@kernel.org>,
David Rientjes <rientjes@google.com>,
Matthew Wilcox <willy@infradead.org>,
"Eric W . Biederman" <ebiederm@xmission.com>,
"Guilherme G . Piccoli" <gpiccoli@canonical.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Christian Brauner <christian.brauner@ubuntu.com>
Subject: Re: [PATCH 2/3] kernel/sysctl: support handling command line aliases
Date: Mon, 30 Mar 2020 10:41:11 -0700 [thread overview]
Message-ID: <202003301041.86E6C7EB@keescook> (raw)
In-Reply-To: <20200330115535.3215-3-vbabka@suse.cz>
On Mon, Mar 30, 2020 at 01:55:34PM +0200, Vlastimil Babka wrote:
> We can now handle sysctl parameters on kernel command line, but historically
> some parameters introduced their own command line equivalent, which we don't
> want to remove for compatibility reasons. We can however convert them to the
> generic infrastructure with a table translating the legacy command line
> parameters to their sysctl names, and removing the one-off param handlers.
>
> This patch adds the support and makes the first conversion to demonstrate it,
> on the (deprecated) numa_zonelist_order parameter.
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kees Cook <keescook@chromium.org>
-Kees
> ---
> fs/proc/proc_sysctl.c | 48 ++++++++++++++++++++++++++++++++++++-------
> mm/page_alloc.c | 9 --------
> 2 files changed, 41 insertions(+), 16 deletions(-)
>
> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
> index 653188c9c4c9..97eb0b552bf8 100644
> --- a/fs/proc/proc_sysctl.c
> +++ b/fs/proc/proc_sysctl.c
> @@ -1727,6 +1727,37 @@ int __init proc_sys_init(void)
> return sysctl_init();
> }
>
> +struct sysctl_alias {
> + const char *kernel_param;
> + const char *sysctl_param;
> +};
> +
> +/*
> + * Historically some settings had both sysctl and a command line parameter.
> + * With the generic sysctl. parameter support, we can handle them at a single
> + * place and only keep the historical name for compatibility. This is not meant
> + * to add brand new aliases. When adding existing aliases, consider whether
> + * the possibly different moment of changing the value (e.g. from early_param
> + * to the moment do_sysctl_args() is called) is an issue for the specific
> + * parameter.
> + */
> +static const struct sysctl_alias sysctl_aliases[] = {
> + {"numa_zonelist_order", "vm.numa_zonelist_order" },
> + { }
> +};
> +
> +static const char *sysctl_find_alias(char *param)
> +{
> + const struct sysctl_alias *alias;
> +
> + for (alias = &sysctl_aliases[0]; alias->kernel_param != NULL; alias++) {
> + if (strcmp(alias->kernel_param, param) == 0)
> + return alias->sysctl_param;
> + }
> +
> + return NULL;
> +}
> +
> /* Set sysctl value passed on kernel command line. */
> static int process_sysctl_arg(char *param, char *val,
> const char *unused, void *arg)
> @@ -1740,15 +1771,18 @@ static int process_sysctl_arg(char *param, char *val,
> loff_t pos = 0;
> ssize_t wret;
>
> - if (strncmp(param, "sysctl", sizeof("sysctl") - 1))
> - return 0;
> -
> - param += sizeof("sysctl") - 1;
> + if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) {
> + param += sizeof("sysctl") - 1;
>
> - if (param[0] != '/' && param[0] != '.')
> - return 0;
> + if (param[0] != '/' && param[0] != '.')
> + return 0;
>
> - param++;
> + param++;
> + } else {
> + param = (char *) sysctl_find_alias(param);
> + if (!param)
> + return 0;
> + }
>
> if (!proc_mnt) {
> proc_fs_type = get_fs_type("proc");
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 3c4eb750a199..de7a134b1b8a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5460,15 +5460,6 @@ static int __parse_numa_zonelist_order(char *s)
> return 0;
> }
>
> -static __init int setup_numa_zonelist_order(char *s)
> -{
> - if (!s)
> - return 0;
> -
> - return __parse_numa_zonelist_order(s);
> -}
> -early_param("numa_zonelist_order", setup_numa_zonelist_order);
> -
> char numa_zonelist_order[] = "Node";
>
> /*
> --
> 2.25.1
>
--
Kees Cook
next prev parent reply other threads:[~2020-03-30 17:41 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-30 11:55 [PATCH 0/3] support setting sysctl parameters from kernel command line Vlastimil Babka
2020-03-30 11:55 ` [PATCH 1/3] kernel/sysctl: " Vlastimil Babka
2020-03-30 16:23 ` Vlastimil Babka
2020-03-30 17:40 ` Kees Cook
2020-03-30 17:39 ` Kees Cook
2020-03-30 22:44 ` Luis Chamberlain
2020-03-31 7:42 ` Vlastimil Babka
2020-03-31 7:48 ` Michal Hocko
2020-03-31 18:26 ` Kees Cook
2020-03-31 14:31 ` Luis Chamberlain
2020-04-01 11:01 ` Vlastimil Babka
2020-04-02 16:04 ` Luis Chamberlain
2020-04-02 17:23 ` Kees Cook
2020-04-02 20:59 ` Luis Chamberlain
2020-04-03 23:57 ` Kees Cook
2020-04-06 14:08 ` Luis Chamberlain
2020-04-06 15:58 ` Kees Cook
2020-04-06 17:08 ` Luis Chamberlain
2020-04-14 11:25 ` Vlastimil Babka
2020-04-15 3:23 ` Masami Hiramatsu
2020-04-15 6:08 ` Luis Chamberlain
2020-03-30 11:55 ` [PATCH 2/3] kernel/sysctl: support handling command line aliases Vlastimil Babka
2020-03-30 17:41 ` Kees Cook [this message]
2020-03-31 14:35 ` Luis Chamberlain
2020-03-30 11:55 ` [PATCH 3/3] kernel/hung_task convert hung_task_panic boot parameter to sysctl Vlastimil Babka
2020-03-30 17:43 ` Kees Cook
2020-03-31 0:34 ` John Hubbard
2020-03-31 7:27 ` Vlastimil Babka
2020-03-31 15:49 ` John Hubbard
2020-03-31 23:12 ` Tetsuo Handa
2020-04-01 8:47 ` Vlastimil Babka
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