Quoting Miklos Szeredi ([EMAIL PROTECTED]):
> From: Miklos Szeredi <[EMAIL PROTECTED]>
>
> The owner doesn't need sysadmin capabilities to call umount().
>
> Similar behavior as umount(8) on mounts having "user=UID" option in /etc/mtab.
> The difference is that umount also checks /etc/fstab, presumably to exclude
> another mount on the same mountpoint.
>
> Signed-off-by: Miklos Szeredi <[EMAIL PROTECTED]>
Acked-by: Serge Hallyn <[EMAIL PROTECTED]>
> ---
>
> Index: linux/fs/namespace.c
> ===================================================================
> --- linux.orig/fs/namespace.c 2008-01-03 20:52:38.000000000 +0100
> +++ linux/fs/namespace.c 2008-01-03 21:14:16.000000000 +0100
> @@ -894,6 +894,27 @@ static int do_umount(struct vfsmount *mn
> return retval;
> }
>
> +static bool is_mount_owner(struct vfsmount *mnt, uid_t uid)
> +{
> + return (mnt->mnt_flags & MNT_USER) && mnt->mnt_uid == uid;
> +}
> +
> +/*
> + * umount is permitted for
> + * - sysadmin
> + * - mount owner, if not forced umount
> + */
> +static bool permit_umount(struct vfsmount *mnt, int flags)
> +{
> + if (capable(CAP_SYS_ADMIN))
> + return true;
> +
> + if (flags & MNT_FORCE)
> + return false;
> +
> + return is_mount_owner(mnt, current->fsuid);
> +}
> +
> /*
> * Now umount can handle mount points as well as block devices.
> * This is important for filesystems which use unnamed block devices.
> @@ -917,7 +938,7 @@ asmlinkage long sys_umount(char __user *
> goto dput_and_out;
>
> retval = -EPERM;
> - if (!capable(CAP_SYS_ADMIN))
> + if (!permit_umount(nd.path.mnt, flags))
> goto dput_and_out;
>
> retval = do_umount(nd.path.mnt, flags);
>
> --
-
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