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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /mm/maccess.c | |
parent | Initial commit. (diff) | |
download | linux-upstream.tar.xz linux-upstream.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | mm/maccess.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/mm/maccess.c b/mm/maccess.c new file mode 100644 index 000000000..518a25667 --- /dev/null +++ b/mm/maccess.c @@ -0,0 +1,230 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Access kernel or user memory without faulting. + */ +#include <linux/export.h> +#include <linux/mm.h> +#include <linux/uaccess.h> +#include <asm/tlb.h> + +bool __weak copy_from_kernel_nofault_allowed(const void *unsafe_src, + size_t size) +{ + return true; +} + +#define copy_from_kernel_nofault_loop(dst, src, len, type, err_label) \ + while (len >= sizeof(type)) { \ + __get_kernel_nofault(dst, src, type, err_label); \ + dst += sizeof(type); \ + src += sizeof(type); \ + len -= sizeof(type); \ + } + +long copy_from_kernel_nofault(void *dst, const void *src, size_t size) +{ + unsigned long align = 0; + + if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) + align = (unsigned long)dst | (unsigned long)src; + + if (!copy_from_kernel_nofault_allowed(src, size)) + return -ERANGE; + + pagefault_disable(); + if (!(align & 7)) + copy_from_kernel_nofault_loop(dst, src, size, u64, Efault); + if (!(align & 3)) + copy_from_kernel_nofault_loop(dst, src, size, u32, Efault); + if (!(align & 1)) + copy_from_kernel_nofault_loop(dst, src, size, u16, Efault); + copy_from_kernel_nofault_loop(dst, src, size, u8, Efault); + pagefault_enable(); + return 0; +Efault: + pagefault_enable(); + return -EFAULT; +} +EXPORT_SYMBOL_GPL(copy_from_kernel_nofault); + +#define copy_to_kernel_nofault_loop(dst, src, len, type, err_label) \ + while (len >= sizeof(type)) { \ + __put_kernel_nofault(dst, src, type, err_label); \ + dst += sizeof(type); \ + src += sizeof(type); \ + len -= sizeof(type); \ + } + +long copy_to_kernel_nofault(void *dst, const void *src, size_t size) +{ + unsigned long align = 0; + + if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) + align = (unsigned long)dst | (unsigned long)src; + + pagefault_disable(); + if (!(align & 7)) + copy_to_kernel_nofault_loop(dst, src, size, u64, Efault); + if (!(align & 3)) + copy_to_kernel_nofault_loop(dst, src, size, u32, Efault); + if (!(align & 1)) + copy_to_kernel_nofault_loop(dst, src, size, u16, Efault); + copy_to_kernel_nofault_loop(dst, src, size, u8, Efault); + pagefault_enable(); + return 0; +Efault: + pagefault_enable(); + return -EFAULT; +} + +long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count) +{ + const void *src = unsafe_addr; + + if (unlikely(count <= 0)) + return 0; + if (!copy_from_kernel_nofault_allowed(unsafe_addr, count)) + return -ERANGE; + + pagefault_disable(); + do { + __get_kernel_nofault(dst, src, u8, Efault); + dst++; + src++; + } while (dst[-1] && src - unsafe_addr < count); + pagefault_enable(); + + dst[-1] = '\0'; + return src - unsafe_addr; +Efault: + pagefault_enable(); + dst[0] = '\0'; + return -EFAULT; +} + +/** + * copy_from_user_nofault(): safely attempt to read from a user-space location + * @dst: pointer to the buffer that shall take the data + * @src: address to read from. This must be a user address. + * @size: size of the data chunk + * + * Safely read from user address @src to the buffer at @dst. If a kernel fault + * happens, handle that and return -EFAULT. + */ +long copy_from_user_nofault(void *dst, const void __user *src, size_t size) +{ + long ret = -EFAULT; + + if (!__access_ok(src, size)) + return ret; + + if (!nmi_uaccess_okay()) + return ret; + + pagefault_disable(); + ret = __copy_from_user_inatomic(dst, src, size); + pagefault_enable(); + + if (ret) + return -EFAULT; + return 0; +} +EXPORT_SYMBOL_GPL(copy_from_user_nofault); + +/** + * copy_to_user_nofault(): safely attempt to write to a user-space location + * @dst: address to write to + * @src: pointer to the data that shall be written + * @size: size of the data chunk + * + * Safely write to address @dst from the buffer at @src. If a kernel fault + * happens, handle that and return -EFAULT. + */ +long copy_to_user_nofault(void __user *dst, const void *src, size_t size) +{ + long ret = -EFAULT; + + if (access_ok(dst, size)) { + pagefault_disable(); + ret = __copy_to_user_inatomic(dst, src, size); + pagefault_enable(); + } + + if (ret) + return -EFAULT; + return 0; +} +EXPORT_SYMBOL_GPL(copy_to_user_nofault); + +/** + * strncpy_from_user_nofault: - Copy a NUL terminated string from unsafe user + * address. + * @dst: Destination address, in kernel space. This buffer must be at + * least @count bytes long. + * @unsafe_addr: Unsafe user address. + * @count: Maximum number of bytes to copy, including the trailing NUL. + * + * Copies a NUL-terminated string from unsafe user address to kernel buffer. + * + * On success, returns the length of the string INCLUDING the trailing NUL. + * + * If access fails, returns -EFAULT (some data may have been copied + * and the trailing NUL added). + * + * If @count is smaller than the length of the string, copies @count-1 bytes, + * sets the last byte of @dst buffer to NUL and returns @count. + */ +long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr, + long count) +{ + long ret; + + if (unlikely(count <= 0)) + return 0; + + pagefault_disable(); + ret = strncpy_from_user(dst, unsafe_addr, count); + pagefault_enable(); + + if (ret >= count) { + ret = count; + dst[ret - 1] = '\0'; + } else if (ret > 0) { + ret++; + } + + return ret; +} + +/** + * strnlen_user_nofault: - Get the size of a user string INCLUDING final NUL. + * @unsafe_addr: The string to measure. + * @count: Maximum count (including NUL) + * + * Get the size of a NUL-terminated string in user space without pagefault. + * + * Returns the size of the string INCLUDING the terminating NUL. + * + * If the string is too long, returns a number larger than @count. User + * has to check the return value against "> count". + * On exception (or invalid count), returns 0. + * + * Unlike strnlen_user, this can be used from IRQ handler etc. because + * it disables pagefaults. + */ +long strnlen_user_nofault(const void __user *unsafe_addr, long count) +{ + int ret; + + pagefault_disable(); + ret = strnlen_user(unsafe_addr, count); + pagefault_enable(); + + return ret; +} + +void __copy_overflow(int size, unsigned long count) +{ + WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count); +} +EXPORT_SYMBOL(__copy_overflow); |