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SubjectRe: [PATCH 01/13] vfs: verify param type in vfs_parse_sb_flag()
Hi David,

Ping? Have you had a chance of looking at this series?

Köszi,
Miklos

On Wed, Jun 19, 2019 at 2:30 PM Miklos Szeredi <mszeredi@redhat.com> wrote:
>
> vfs_parse_sb_flag() accepted any kind of param with a matching key, not
> just a flag. This is wrong, only allow flag type and return -EINVAL
> otherwise.
>
> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
> ---
> fs/fs_context.c | 31 +++++++++++++++----------------
> 1 file changed, 15 insertions(+), 16 deletions(-)
>
> diff --git a/fs/fs_context.c b/fs/fs_context.c
> index 103643c68e3f..e56310fd8c75 100644
> --- a/fs/fs_context.c
> +++ b/fs/fs_context.c
> @@ -81,30 +81,29 @@ static const char *const forbidden_sb_flag[] = {
> /*
> * Check for a common mount option that manipulates s_flags.
> */
> -static int vfs_parse_sb_flag(struct fs_context *fc, const char *key)
> +static int vfs_parse_sb_flag(struct fs_context *fc, struct fs_parameter *param)
> {
> - unsigned int token;
> + const char *key = param->key;
> + unsigned int set, clear;
> unsigned int i;
>
> for (i = 0; i < ARRAY_SIZE(forbidden_sb_flag); i++)
> if (strcmp(key, forbidden_sb_flag[i]) == 0)
> return -EINVAL;
>
> - token = lookup_constant(common_set_sb_flag, key, 0);
> - if (token) {
> - fc->sb_flags |= token;
> - fc->sb_flags_mask |= token;
> - return 0;
> - }
> + set = lookup_constant(common_set_sb_flag, key, 0);
> + clear = lookup_constant(common_clear_sb_flag, key, 0);
> + if (!set && !clear)
> + return -ENOPARAM;
>
> - token = lookup_constant(common_clear_sb_flag, key, 0);
> - if (token) {
> - fc->sb_flags &= ~token;
> - fc->sb_flags_mask |= token;
> - return 0;
> - }
> + if (param->type != fs_value_is_flag)
> + return invalf(fc, "%s: Unexpected value for '%s'",
> + fc->fs_type->name, param->key);
>
> - return -ENOPARAM;
> + fc->sb_flags |= set;
> + fc->sb_flags &= ~clear;
> + fc->sb_flags_mask |= set | clear;
> + return 0;
> }
>
> /**
> @@ -130,7 +129,7 @@ int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param)
> if (!param->key)
> return invalf(fc, "Unnamed parameter\n");
>
> - ret = vfs_parse_sb_flag(fc, param->key);
> + ret = vfs_parse_sb_flag(fc, param);
> if (ret != -ENOPARAM)
> return ret;
>
> --
> 2.21.0
>

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