diff options
Diffstat (limited to 'include/linux/sockptr.h')
-rw-r--r-- | include/linux/sockptr.h | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/include/linux/sockptr.h b/include/linux/sockptr.h new file mode 100644 index 000000000..ea1934142 --- /dev/null +++ b/include/linux/sockptr.h @@ -0,0 +1,105 @@ +/* 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) +{ + if (sockptr_is_kernel(sockptr)) + return !sockptr.kernel; + return !sockptr.user; +} + +static inline int copy_from_sockptr_offset(void *dst, sockptr_t src, + size_t offset, size_t size) +{ + if (!sockptr_is_kernel(src)) + return copy_from_user(dst, src.user + offset, size); + memcpy(dst, src.kernel + offset, size); + return 0; +} + +static inline int copy_from_sockptr(void *dst, sockptr_t src, size_t size) +{ + return copy_from_sockptr_offset(dst, src, 0, size); +} + +static inline int copy_to_sockptr_offset(sockptr_t dst, size_t offset, + const void *src, size_t size) +{ + if (!sockptr_is_kernel(dst)) + return copy_to_user(dst.user + offset, src, size); + memcpy(dst.kernel + offset, 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 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 */ |