/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (c) 2020 Christoph Hellwig.
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*
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* Support for "universal" pointers that can point to either kernel or userspace
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* memory.
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*/
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#ifndef _LINUX_SOCKPTR_H
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#define _LINUX_SOCKPTR_H
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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typedef struct {
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union {
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void *kernel;
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void __user *user;
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};
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bool is_kernel : 1;
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} sockptr_t;
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static inline bool sockptr_is_kernel(sockptr_t sockptr)
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{
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return sockptr.is_kernel;
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}
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static inline sockptr_t KERNEL_SOCKPTR(void *p)
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{
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return (sockptr_t) { .kernel = p, .is_kernel = true };
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}
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static inline sockptr_t USER_SOCKPTR(void __user *p)
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{
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return (sockptr_t) { .user = p };
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}
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static inline bool sockptr_is_null(sockptr_t sockptr)
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{
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if (sockptr_is_kernel(sockptr))
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return !sockptr.kernel;
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return !sockptr.user;
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}
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static inline int copy_from_sockptr_offset(void *dst, sockptr_t src,
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size_t offset, size_t size)
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{
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if (!sockptr_is_kernel(src))
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return copy_from_user(dst, src.user + offset, size);
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memcpy(dst, src.kernel + offset, size);
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return 0;
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}
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static inline int copy_from_sockptr(void *dst, sockptr_t src, size_t size)
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{
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return copy_from_sockptr_offset(dst, src, 0, size);
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}
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static inline int copy_to_sockptr_offset(sockptr_t dst, size_t offset,
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const void *src, size_t size)
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{
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if (!sockptr_is_kernel(dst))
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return copy_to_user(dst.user + offset, src, size);
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memcpy(dst.kernel + offset, src, size);
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return 0;
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}
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static inline void *memdup_sockptr(sockptr_t src, size_t len)
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{
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void *p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN);
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if (!p)
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return ERR_PTR(-ENOMEM);
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if (copy_from_sockptr(p, src, len)) {
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kfree(p);
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return ERR_PTR(-EFAULT);
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}
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return p;
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}
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static inline void *memdup_sockptr_nul(sockptr_t src, size_t len)
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{
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char *p = kmalloc_track_caller(len + 1, GFP_KERNEL);
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if (!p)
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return ERR_PTR(-ENOMEM);
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if (copy_from_sockptr(p, src, len)) {
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kfree(p);
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return ERR_PTR(-EFAULT);
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}
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p[len] = '\0';
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return p;
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}
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static inline long strncpy_from_sockptr(char *dst, sockptr_t src, size_t count)
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{
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if (sockptr_is_kernel(src)) {
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size_t len = min(strnlen(src.kernel, count - 1) + 1, count);
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memcpy(dst, src.kernel, len);
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return len;
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}
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return strncpy_from_user(dst, src.user, count);
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}
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#endif /* _LINUX_SOCKPTR_H */
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