[PATCH 4.9 03/58] uapi/if_ether.h: prevent redefinition of struct ethhdr

From: Greg Kroah-Hartman
Date: Mon Feb 18 2019 - 09:31:27 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------

commit 6926e041a8920c8ec27e4e155efa760aa01551fd upstream.

Musl provides its own ethhdr struct definition. Add a guard to prevent
its definition of the appropriate musl header has already been included.

glibc does not implement this header, but when glibc will implement this
they can just define __UAPI_DEF_ETHHDR 0 to make it work with the
kernel.

Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
include/uapi/linux/if_ether.h | 3 +++
include/uapi/linux/libc-compat.h | 6 ++++++
2 files changed, 9 insertions(+)

diff --git a/include/uapi/linux/if_ether.h b/include/uapi/linux/if_ether.h
index 659b1634de61..b31e2f836317 100644
--- a/include/uapi/linux/if_ether.h
+++ b/include/uapi/linux/if_ether.h
@@ -22,6 +22,7 @@
#define _UAPI_LINUX_IF_ETHER_H

#include <linux/types.h>
+#include <linux/libc-compat.h>

/*
* IEEE 802.3 Ethernet magic constants. The frame sizes omit the preamble
@@ -139,11 +140,13 @@
* This is an Ethernet frame header.
*/

+#if __UAPI_DEF_ETHHDR
struct ethhdr {
unsigned char h_dest[ETH_ALEN]; /* destination eth addr */
unsigned char h_source[ETH_ALEN]; /* source ether addr */
__be16 h_proto; /* packet type ID field */
} __attribute__((packed));
+#endif


#endif /* _UAPI_LINUX_IF_ETHER_H */
diff --git a/include/uapi/linux/libc-compat.h b/include/uapi/linux/libc-compat.h
index 774cb2db1b89..7c098d68d5e5 100644
--- a/include/uapi/linux/libc-compat.h
+++ b/include/uapi/linux/libc-compat.h
@@ -263,4 +263,10 @@

#endif /* __GLIBC__ */

+/* Definitions for if_ether.h */
+/* allow libcs like musl to deactivate this, glibc does not implement this. */
+#ifndef __UAPI_DEF_ETHHDR
+#define __UAPI_DEF_ETHHDR 1
+#endif
+
#endif /* _UAPI_LIBC_COMPAT_H */
--
2.19.1