Re: [PATCH] userns: Convert quota to user kuid/kgid where appropriate

[ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman)]

Dmitry Monakhov <dmonakhov-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org> writes:

> Map uid/gid to global kuid/kgid before pass it down to quota
> infrastructure.

Have you looked at my development branch of my userns tree?

I already have a patch queued to do something like this. 

Eric

> Signed-off-by: Dmitry Monakhov <dmonakhov-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>
> ---
>  fs/quota/quota.c |   45 ++++++++++++++++++++++++++++++++++++---------
>  1 files changed, 36 insertions(+), 9 deletions(-)
>
> diff --git a/fs/quota/quota.c b/fs/quota/quota.c
> index 6f15578..a59efd4 100644
> --- a/fs/quota/quota.c
> +++ b/fs/quota/quota.c
> @@ -19,8 +19,13 @@
>  #include <linux/writeback.h>
>  
>  static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
> -				     qid_t id)
> +				     qid_t id, qid_t* global_id)
>  {
> +	kuid_t kuid;
> +	kgid_t kgid;
> +	struct user_namespace *ns = current_user_ns();
> +	int is_get_query = 0;
> +
>  	switch (cmd) {
>  	/* these commands do not require any special privilegues */
>  	case Q_GETFMT:
> @@ -29,11 +34,32 @@ static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
>  	case Q_XGETQSTAT:
>  	case Q_XQUOTASYNC:
>  		break;
> -	/* allow to query information for dquots we "own" */
>  	case Q_GETQUOTA:
>  	case Q_XGETQUOTA:
> -		if ((type == USRQUOTA && current_euid() == id) ||
> -		    (type == GRPQUOTA && in_egroup_p(id)))
> +		is_get_query = 1;
> +	case Q_SETQUOTA:
> +	case Q_XSETQLIM:
> +		/* Map to global user namespace */
> +		switch (type) {
> +		case USRQUOTA:
> +			kuid = make_kuid(ns, id);
> +			if (!uid_valid(kuid))
> +				return -EINVAL;
> +			*global_id = from_kuid_munged(&init_user_ns, kuid);
> +			break;
> +		case GRPQUOTA:
> +			kgid = make_kgid(ns, id);
> +			if (!gid_valid(kgid))
> +				return -EINVAL;
> +			*global_id = from_kgid_munged(&init_user_ns, kgid);
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +		/* allow to query information for dquots we "own" */
> +		if (is_get_query &&
> +		    ((type == USRQUOTA && uid_eq(current_euid(), kuid)) ||
> +		     (type == GRPQUOTA && in_egroup_p(kgid))))
>  			break;
>  		/*FALLTHROUGH*/
>  	default:
> @@ -240,13 +266,14 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
>  		       void __user *addr, struct path *path)
>  {
>  	int ret;
> +	qid_t qid = -1;
>  
>  	if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
>  		return -EINVAL;
>  	if (!sb->s_qcop)
>  		return -ENOSYS;
>  
> -	ret = check_quotactl_permission(sb, type, cmd, id);
> +	ret = check_quotactl_permission(sb, type, cmd, id, &qid);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -264,9 +291,9 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
>  	case Q_SETINFO:
>  		return quota_setinfo(sb, type, addr);
>  	case Q_GETQUOTA:
> -		return quota_getquota(sb, type, id, addr);
> +		return quota_getquota(sb, type, qid, addr);
>  	case Q_SETQUOTA:
> -		return quota_setquota(sb, type, id, addr);
> +		return quota_setquota(sb, type, qid, addr);
>  	case Q_SYNC:
>  		if (!sb->s_qcop->quota_sync)
>  			return -ENOSYS;
> @@ -278,9 +305,9 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
>  	case Q_XGETQSTAT:
>  		return quota_getxstate(sb, addr);
>  	case Q_XSETQLIM:
> -		return quota_setxquota(sb, type, id, addr);
> +		return quota_setxquota(sb, type, qid, addr);
>  	case Q_XGETQUOTA:
> -		return quota_getxquota(sb, type, id, addr);
> +		return quota_getxquota(sb, type, qid, addr);
>  	case Q_XQUOTASYNC:
>  		if (sb->s_flags & MS_RDONLY)
>  			return -EROFS;