2020-05-29 07:43:48

by Luis Chamberlain

Subject: [PATCH 13/13] fs: move binfmt_misc sysctl to its own file

This moves the binfmt_misc sysctl to its own file to help remove
clutter from kernel/sysctl.c.

Signed-off-by: Luis Chamberlain <[email protected]>
---
fs/binfmt_misc.c | 1 +
kernel/sysctl.c | 7 -------
2 files changed, 1 insertion(+), 7 deletions(-)

diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index f69a043f562b..656b3f5f3bbf 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -821,6 +821,7 @@ static int __init init_misc_binfmt(void)
int err = register_filesystem(&bm_fs_type);
if (!err)
insert_binfmt(&misc_format);
+ register_sysctl_empty_subdir("fs", "binfmt_misc");
return err;
}

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 460532cd5ac8..7714e7b476c2 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -3042,13 +3042,6 @@ static struct ctl_table fs_table[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_TWO,
},
-#if defined(CONFIG_BINFMT_MISC) || defined(CONFIG_BINFMT_MISC_MODULE)
- {
- .procname = "binfmt_misc",
- .mode = 0555,
- .child = sysctl_mount_point,
- },
-#endif
{
.procname = "pipe-max-size",
.data = &pipe_max_size,
--
2.26.2

2020-05-29 08:17:21

by Kees Cook

Subject: Re: [PATCH 13/13] fs: move binfmt_misc sysctl to its own file

On Fri, May 29, 2020 at 07:41:08AM +0000, Luis Chamberlain wrote:
> This moves the binfmt_misc sysctl to its own file to help remove
> clutter from kernel/sysctl.c.
>
> Signed-off-by: Luis Chamberlain <[email protected]>
> ---
> fs/binfmt_misc.c | 1 +
> kernel/sysctl.c | 7 -------
> 2 files changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
> index f69a043f562b..656b3f5f3bbf 100644
> --- a/fs/binfmt_misc.c
> +++ b/fs/binfmt_misc.c
> @@ -821,6 +821,7 @@ static int __init init_misc_binfmt(void)
> int err = register_filesystem(&bm_fs_type);
> if (!err)
> insert_binfmt(&misc_format);
> + register_sysctl_empty_subdir("fs", "binfmt_misc");
> return err;

Nit: let's make the dir before registering the filesystem. I can't
imagine a realistic situation where userspace is reacting so fast it
would actually fail to mount the fs on /proc/sys/fs/binfmt_misc, but why
risk it?

-Kees

> }
>
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 460532cd5ac8..7714e7b476c2 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -3042,13 +3042,6 @@ static struct ctl_table fs_table[] = {
> .extra1 = SYSCTL_ZERO,
> .extra2 = SYSCTL_TWO,
> },
> -#if defined(CONFIG_BINFMT_MISC) || defined(CONFIG_BINFMT_MISC_MODULE)
> - {
> - .procname = "binfmt_misc",
> - .mode = 0555,
> - .child = sysctl_mount_point,
> - },
> -#endif
> {
> .procname = "pipe-max-size",
> .data = &pipe_max_size,
> --
> 2.26.2
>

--
Kees Cook

2020-06-04 08:51:11

by Xiaoming Ni

Subject: Re: [PATCH 13/13] fs: move binfmt_misc sysctl to its own file

On 2020/5/29 15:41, Luis Chamberlain wrote:
> This moves the binfmt_misc sysctl to its own file to help remove
> clutter from kernel/sysctl.c.
>
> Signed-off-by: Luis Chamberlain <[email protected]>
> ---
> fs/binfmt_misc.c | 1 +
> kernel/sysctl.c | 7 -------
> 2 files changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
> index f69a043f562b..656b3f5f3bbf 100644
> --- a/fs/binfmt_misc.c
> +++ b/fs/binfmt_misc.c
> @@ -821,6 +821,7 @@ static int __init init_misc_binfmt(void)
> int err = register_filesystem(&bm_fs_type);
> if (!err)
> insert_binfmt(&misc_format);
> + register_sysctl_empty_subdir("fs", "binfmt_misc");
> return err;
> }
build error when CONFIG_BINFMT_MISC=m

ERROR: modpost: "register_sysctl_empty_subdir" [fs/binfmt_misc.ko]
undefined!

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 27f0c9ea..4129dfb 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2853,6 +2853,7 @@ void register_sysctl_empty_subdir(const char *base,
{
register_sysctl_subdir(base, subdir, sysctl_mount_point);
}
+EXPORT_SYMBOL_GPL(register_sysctl_empty_subdir);
#endif /* CONFIG_SYSCTL */


Thanks
Xiaoming Ni