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-rw-r--r--mm/maccess.c76
1 files changed, 76 insertions, 0 deletions
diff --git a/mm/maccess.c b/mm/maccess.c
index 17b26bceb716..db7cf48d8fed 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -11,6 +11,81 @@ bool __weak probe_kernel_read_allowed(const void *unsafe_src, size_t size)
return true;
}
+#ifdef HAVE_GET_KERNEL_NOFAULT
+
+#define probe_kernel_read_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 probe_kernel_read(void *dst, const void *src, size_t size)
+{
+ if (!probe_kernel_read_allowed(src, size))
+ return -EFAULT;
+
+ pagefault_disable();
+ probe_kernel_read_loop(dst, src, size, u64, Efault);
+ probe_kernel_read_loop(dst, src, size, u32, Efault);
+ probe_kernel_read_loop(dst, src, size, u16, Efault);
+ probe_kernel_read_loop(dst, src, size, u8, Efault);
+ pagefault_enable();
+ return 0;
+Efault:
+ pagefault_enable();
+ return -EFAULT;
+}
+EXPORT_SYMBOL_GPL(probe_kernel_read);
+
+#define probe_kernel_write_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 probe_kernel_write(void *dst, const void *src, size_t size)
+{
+ pagefault_disable();
+ probe_kernel_write_loop(dst, src, size, u64, Efault);
+ probe_kernel_write_loop(dst, src, size, u32, Efault);
+ probe_kernel_write_loop(dst, src, size, u16, Efault);
+ probe_kernel_write_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 (!probe_kernel_read_allowed(unsafe_addr, count))
+ return -EFAULT;
+
+ 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[-1] = '\0';
+ return -EFAULT;
+}
+#else /* HAVE_GET_KERNEL_NOFAULT */
/**
* probe_kernel_read(): safely attempt to read from kernel-space
* @dst: pointer to the buffer that shall take the data
@@ -113,6 +188,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
return ret ? -EFAULT : src - unsafe_addr;
}
+#endif /* HAVE_GET_KERNEL_NOFAULT */
/**
* probe_user_read(): safely attempt to read from a user-space location