bpf/progs/test_pkt_md_access.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /* Copyright (c) 2017 Facebook
0003  */
0004 #include <stddef.h>
0005 #include <string.h>
0006 #include <linux/bpf.h>
0007 #include <linux/pkt_cls.h>
0008 #include <bpf/bpf_helpers.h>
0009
0010 #if  __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
0011 #define TEST_FIELD(TYPE, FIELD, MASK)                   \
0012     {                               \
0013         TYPE tmp = *(volatile TYPE *)&skb->FIELD;       \
0014         if (tmp != ((*(volatile __u32 *)&skb->FIELD) & MASK))   \
0015             return TC_ACT_SHOT;             \
0016     }
0017 #else
0018 #define TEST_FIELD_OFFSET(a, b) ((sizeof(a) - sizeof(b)) / sizeof(b))
0019 #define TEST_FIELD(TYPE, FIELD, MASK)                   \
0020     {                               \
0021         TYPE tmp = *((volatile TYPE *)&skb->FIELD +     \
0022                   TEST_FIELD_OFFSET(skb->FIELD, TYPE)); \
0023         if (tmp != ((*(volatile __u32 *)&skb->FIELD) & MASK))   \
0024             return TC_ACT_SHOT;             \
0025     }
0026 #endif
0027
0028 SEC("tc")
0029 int test_pkt_md_access(struct __sk_buff *skb)
0030 {
0031     TEST_FIELD(__u8,  len, 0xFF);
0032     TEST_FIELD(__u16, len, 0xFFFF);
0033     TEST_FIELD(__u32, len, 0xFFFFFFFF);
0034     TEST_FIELD(__u16, protocol, 0xFFFF);
0035     TEST_FIELD(__u32, protocol, 0xFFFFFFFF);
0036     TEST_FIELD(__u8,  hash, 0xFF);
0037     TEST_FIELD(__u16, hash, 0xFFFF);
0038     TEST_FIELD(__u32, hash, 0xFFFFFFFF);
0039
0040     return TC_ACT_OK;
0041 }