Re: [PATCH 2/3] Expose may_setuid() in user.h and add may_setgid() (v2)

["Serge E. Hallyn" <serue@us.ibm.com>]

Quoting Dan Smith (danms@us.ibm.com):
> Make these helpers available to others.
> 
> Changes in v2:
>  - Avoid checking the groupinfo in ctx->realcred against the current in
>    may_setgid()
> 
> Cc: Serge Hallyn <serue@us.ibm.com>

Acked-by: Serge Hallyn <serue@us.ibm.com>

> Signed-off-by: Dan Smith <danms@us.ibm.com>
> ---
>  include/linux/user.h |    9 +++++++++
>  kernel/user.c        |   13 ++++++++++++-
>  2 files changed, 21 insertions(+), 1 deletions(-)
> 
> diff --git a/include/linux/user.h b/include/linux/user.h
> index 68daf84..c231e9c 100644
> --- a/include/linux/user.h
> +++ b/include/linux/user.h
> @@ -1 +1,10 @@
> +#ifndef _LINUX_USER_H
> +#define _LINUX_USER_H
> +
>  #include <asm/user.h>
> +#include <linux/sched.h>
> +
> +extern int may_setuid(struct user_namespace *ns, uid_t uid);
> +extern int may_setgid(gid_t gid);
> +
> +#endif
> diff --git a/kernel/user.c b/kernel/user.c
> index a535ed6..a78fde7 100644
> --- a/kernel/user.c
> +++ b/kernel/user.c
> @@ -604,7 +604,7 @@ int checkpoint_user(struct ckpt_ctx *ctx, void *ptr)
>  	return do_checkpoint_user(ctx, (struct user_struct *) ptr);
>  }
> 
> -static int may_setuid(struct user_namespace *ns, uid_t uid)
> +int may_setuid(struct user_namespace *ns, uid_t uid)
>  {
>  	/*
>  	 * this next check will one day become
> @@ -631,6 +631,17 @@ static int may_setuid(struct user_namespace *ns, uid_t uid)
>  	return 0;
>  }
> 
> +int may_setgid(gid_t gid)
> +{
> +	if (capable(CAP_SETGID))
> +		return 1;
> +
> +	if (in_egroup_p(gid))
> +		return 1;
> +
> +	return 0;
> +}
> +
>  static struct user_struct *do_restore_user(struct ckpt_ctx *ctx)
>  {
>  	struct user_struct *u;
> -- 
> 1.6.2.5