Commit ba423fda authored by Christoph Hellwig's avatar Christoph Hellwig Committed by David S. Miller
Browse files

net: add a new sockptr_t type 



Add a uptr_t type that can hold a pointer to either a user or kernel
memory region, and simply helpers to copy to and from it.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d200cf62

include/linux/sockptr.h

0 → 100644
+104 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/*

 * Copyright (c) 2020 Christoph Hellwig.

 *

 * Support for "universal" pointers that can point to either kernel or userspace

 * memory.

 */

#ifndef _LINUX_SOCKPTR_H

#define _LINUX_SOCKPTR_H



#include <linux/slab.h>

#include <linux/uaccess.h>



typedef struct {

	union {

		void		*kernel;

		void __user	*user;

	};

	bool		is_kernel : 1;

} sockptr_t;



static inline bool sockptr_is_kernel(sockptr_t sockptr)

{

	return sockptr.is_kernel;

}



static inline sockptr_t KERNEL_SOCKPTR(void *p)

{

	return (sockptr_t) { .kernel = p, .is_kernel = true };

}



static inline sockptr_t USER_SOCKPTR(void __user *p)

{

	return (sockptr_t) { .user = p };

}



static inline bool sockptr_is_null(sockptr_t sockptr)

{

	return !sockptr.user && !sockptr.kernel;

}



static inline int copy_from_sockptr(void *dst, sockptr_t src, size_t size)

{

	if (!sockptr_is_kernel(src))

		return copy_from_user(dst, src.user, size);

	memcpy(dst, src.kernel, size);

	return 0;

}



static inline int copy_to_sockptr(sockptr_t dst, const void *src, size_t size)

{

	if (!sockptr_is_kernel(dst))

		return copy_to_user(dst.user, src, size);

	memcpy(dst.kernel, src, size);

	return 0;

}



static inline void *memdup_sockptr(sockptr_t src, size_t len)

{

	void *p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN);



	if (!p)

		return ERR_PTR(-ENOMEM);

	if (copy_from_sockptr(p, src, len)) {

		kfree(p);

		return ERR_PTR(-EFAULT);

	}

	return p;

}



static inline void *memdup_sockptr_nul(sockptr_t src, size_t len)

{

	char *p = kmalloc_track_caller(len + 1, GFP_KERNEL);



	if (!p)

		return ERR_PTR(-ENOMEM);

	if (copy_from_sockptr(p, src, len)) {

		kfree(p);

		return ERR_PTR(-EFAULT);

	}

	p[len] = '\0';

	return p;

}



static inline void sockptr_advance(sockptr_t sockptr, size_t len)

{

	if (sockptr_is_kernel(sockptr))

		sockptr.kernel += len;

	else

		sockptr.user += len;

}



static inline long strncpy_from_sockptr(char *dst, sockptr_t src, size_t count)

{

	if (sockptr_is_kernel(src)) {

		size_t len = min(strnlen(src.kernel, count - 1) + 1, count);



		memcpy(dst, src.kernel, len);

		return len;

	}

	return strncpy_from_user(dst, src.user, count);

}



#endif /* _LINUX_SOCKPTR_H */