memzero_explicit() was added in Linux commit d4c5efdb9 "random: add and
use memzero_explicit() for clearing data" and is used by skcipher.
Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
---
backport/backport-include/linux/string.h | 17 ++++++++++++++++
backport/compat/backport-3.18.c | 34 ++++++++++++++++++++++++++++++++
2 files changed, 51 insertions(+)
diff --git a/backport/backport-include/linux/string.h b/backport/backport-include/linux/string.h
index f585862..e8c5cb0 100644
--- a/backport/backport-include/linux/string.h
+++ b/backport/backport-include/linux/string.h
@@ -8,4 +8,21 @@
extern void *memdup_user_nul(const void __user *, size_t);
#endif
+/* this was added in v3.2.65, v3.4.106, v3.10.60, v3.12.33, v3.14.24,
+ * v3.17.3 and v3.18 */
+#if !(LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,3) || \
+ (LINUX_VERSION_CODE >= KERNEL_VERSION(3,14,24) && \
+ LINUX_VERSION_CODE < KERNEL_VERSION(3,15,0)) || \
+ (LINUX_VERSION_CODE >= KERNEL_VERSION(3,12,33) && \
+ LINUX_VERSION_CODE < KERNEL_VERSION(3,13,0)) || \
+ (LINUX_VERSION_CODE >= KERNEL_VERSION(3,10,60) && \
+ LINUX_VERSION_CODE < KERNEL_VERSION(3,11,0)) || \
+ (LINUX_VERSION_CODE >= KERNEL_VERSION(3,4,106) && \
+ LINUX_VERSION_CODE < KERNEL_VERSION(3,5,0)) || \
+ (LINUX_VERSION_CODE >= KERNEL_VERSION(3,2,65) && \
+ LINUX_VERSION_CODE < KERNEL_VERSION(3,3,0)))
+#define memzero_explicit LINUX_BACKPORT(memzero_explicit)
+void memzero_explicit(void *s, size_t count);
+#endif
+
#endif /* __BACKPORT_LINUX_STRING_H */
diff --git a/backport/compat/backport-3.18.c b/backport/compat/backport-3.18.c
index f0f7fd8..5c3e751 100644
--- a/backport/compat/backport-3.18.c
+++ b/backport/compat/backport-3.18.c
@@ -16,6 +16,7 @@
#include <linux/errqueue.h>
#include <linux/wait.h>
#include <linux/of.h>
+#include <linux/string.h>
/**
* eth_get_headlen - determine the the length of header for an ethernet frame
@@ -286,3 +287,36 @@ int of_property_read_u64_array(const struct device_node *np,
}
EXPORT_SYMBOL_GPL(of_property_read_u64_array);
#endif /* CONFIG_OF */
+
+#if !(LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,3) || \
+ (LINUX_VERSION_CODE >= KERNEL_VERSION(3,14,24) && \
+ LINUX_VERSION_CODE < KERNEL_VERSION(3,15,0)) || \
+ (LINUX_VERSION_CODE >= KERNEL_VERSION(3,12,33) && \
+ LINUX_VERSION_CODE < KERNEL_VERSION(3,13,0)) || \
+ (LINUX_VERSION_CODE >= KERNEL_VERSION(3,10,60) && \
+ LINUX_VERSION_CODE < KERNEL_VERSION(3,11,0)) || \
+ (LINUX_VERSION_CODE >= KERNEL_VERSION(3,4,106) && \
+ LINUX_VERSION_CODE < KERNEL_VERSION(3,5,0)) || \
+ (LINUX_VERSION_CODE >= KERNEL_VERSION(3,2,65) && \
+ LINUX_VERSION_CODE < KERNEL_VERSION(3,3,0)))
+/**
+ * memzero_explicit - Fill a region of memory (e.g. sensitive
+ * keying data) with 0s.
+ * @s: Pointer to the start of the area.
+ * @count: The size of the area.
+ *
+ * Note: usually using memset() is just fine (!), but in cases
+ * where clearing out _local_ data at the end of a scope is
+ * necessary, memzero_explicit() should be used instead in
+ * order to prevent the compiler from optimising away zeroing.
+ *
+ * memzero_explicit() doesn't need an arch-specific version as
+ * it just invokes the one of memset() implicitly.
+ */
+void memzero_explicit(void *s, size_t count)
+{
+ memset(s, 0, count);
+ barrier_data(s);
+}
+EXPORT_SYMBOL_GPL(memzero_explicit);
+#endif
--
2.8.1
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