[v2] net/cksum: compute raw cksum for several segments
Su Sai
susai.ss at bytedance.com
Fri Aug 1 17:28:46 CEST 2025
The rte_raw_cksum_mbuf function is used to compute
the raw checksum of a packet.
If the packet payload stored in multi mbuf, the function
will goto the hard case. In hard case,
the variable 'tmp' is a type of uint32_t,
so rte_bswap16 will drop high 16 bit.
Meanwhile, the variable 'sum' is a type of uint32_t,
so 'sum += tmp' will drop the carry when overflow.
Both drop will make cksum incorrect.
This commit fixes the above bug.
Signed-off-by: Su Sai <susai.ss at bytedance.com>
---
.mailmap | 1 +
app/test/test_cksum.c | 104 ++++++++++++++++++++++++++++++++++++++++++
lib/net/rte_cksum.h | 26 +++++++++--
3 files changed, 128 insertions(+), 3 deletions(-)
diff --git a/.mailmap b/.mailmap
index 34a99f93a1..838b544a97 100644
--- a/.mailmap
+++ b/.mailmap
@@ -1891,3 +1891,4 @@ Zoltan Kiss <zoltan.kiss at schaman.hu>
<zoltan.kiss at linaro.org>
Zorik Machulsky <zorik at amazon.com>
Zyta Szpak <zyta at marvell.com> <zr at semihalf.com>
Zyta Szpak <zyta at marvell.com> <zyta.szpak at semihalf.com>
+Su Sai <susai.ss at bytedance.com>
diff --git a/app/test/test_cksum.c b/app/test/test_cksum.c
index f2ab5af5a7..d2435a9962 100644
--- a/app/test/test_cksum.c
+++ b/app/test/test_cksum.c
@@ -85,6 +85,39 @@ static const char test_cksum_ipv4_opts_udp[] = {
0x00, 0x35, 0x00, 0x09, 0x89, 0x6f, 0x78,
};
+/* generated in scapy with
Ether()/IP()/TCP(options=[NOP,NOP,Timestamps])/os.urandom(113)) */
+static const char test_cksum_ipv4_tcp_multi_segs[] = {
+ 0x00, 0x16, 0x3e, 0x0b, 0x6b, 0xd2, 0xee, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0x08, 0x00, 0x45, 0x00,
+ 0x00, 0xa5, 0x46, 0x10, 0x40, 0x00, 0x40, 0x06,
+ 0x80, 0xb5, 0xc0, 0xa8, 0xf9, 0x1d, 0xc0, 0xa8,
+ 0xf9, 0x1e, 0xdc, 0xa2, 0x14, 0x51, 0xbb, 0x8f,
+ 0xa0, 0x00, 0xe4, 0x7c, 0xe4, 0xb8, 0x80, 0x10,
+ 0x02, 0x00, 0x4b, 0xc1, 0x00, 0x00, 0x01, 0x01,
+ 0x08, 0x0a, 0x90, 0x60, 0xf4, 0xff, 0x03, 0xc5,
+ 0xb4, 0x19, 0x77, 0x34, 0xd4, 0xdc, 0x84, 0x86,
+ 0xff, 0x44, 0x09, 0x63, 0x36, 0x2e, 0x26, 0x9b,
+ 0x90, 0x70, 0xf2, 0xed, 0xc8, 0x5b, 0x87, 0xaa,
+ 0xb4, 0x67, 0x6b, 0x32, 0x3d, 0xc4, 0xbf, 0x15,
+ 0xa9, 0x16, 0x6c, 0x2a, 0x9d, 0xb2, 0xb7, 0x6b,
+ 0x58, 0x44, 0x58, 0x12, 0x4b, 0x8f, 0xe5, 0x12,
+ 0x11, 0x90, 0x94, 0x68, 0x37, 0xad, 0x0a, 0x9b,
+ 0xd6, 0x79, 0xf2, 0xb7, 0x31, 0xcf, 0x44, 0x22,
+ 0xc8, 0x99, 0x3f, 0xe5, 0xe7, 0xac, 0xc7, 0x0b,
+ 0x86, 0xdf, 0xda, 0xed, 0x0a, 0x0f, 0x86, 0xd7,
+ 0x48, 0xe2, 0xf1, 0xc2, 0x43, 0xed, 0x47, 0x3a,
+ 0xea, 0x25, 0x2d, 0xd6, 0x60, 0x38, 0x30, 0x07,
+ 0x28, 0xdd, 0x1f, 0x0c, 0xdd, 0x7b, 0x7c, 0xd9,
+ 0x35, 0x9d, 0x14, 0xaa, 0xc6, 0x35, 0xd1, 0x03,
+ 0x38, 0xb1, 0xf5,
+};
+
+static const uint8_t test_cksum_ipv4_tcp_multi_segs_len[] = {
+ 66, /* the first seg contains all headers, including L2 to L4 */
+ 61, /* the second seg lenght is odd, test byte order independent */
+ 52, /* three segs are sufficient to test the most complex scenarios */
+};
+
/* test l3/l4 checksum api */
static int
test_l4_cksum(struct rte_mempool *pktmbuf_pool, const char *pktdata,
size_t len)
@@ -223,6 +256,71 @@ test_l4_cksum(struct rte_mempool *pktmbuf_pool,
const char *pktdata, size_t len)
return -1;
}
+/* test l4 checksum api for a packet with multiple mbufs */
+static int
+test_l4_cksum_multi_mbufs(struct rte_mempool *pktmbuf_pool, const
char *pktdata, size_t len,
+ const uint8_t *segs, size_t segs_len)
+{
+ struct rte_mbuf *m[NB_MBUF] = {0};
+ struct rte_mbuf *m_hdr = NULL;
+ struct rte_net_hdr_lens hdr_lens;
+ size_t i, off = 0;
+ uint32_t packet_type;
+ void *l3_hdr;
+ uint32_t l3;
+ char *data;
+
+ for (i = 0; i < segs_len; i++) {
+ m[i] = rte_pktmbuf_alloc(pktmbuf_pool);
+ if (m[i] == NULL)
+ GOTO_FAIL("Cannot allocate mbuf");
+
+ data = rte_pktmbuf_append(m[i], segs[i]);
+ if (data == NULL)
+ GOTO_FAIL("Cannot append data");
+
+ rte_memcpy(data, pktdata + off, segs[i]);
+ off += segs[i];
+
+ if (m_hdr) {
+ if (rte_pktmbuf_chain(m_hdr, m[i]))
+ GOTO_FAIL("Cannot chain mbuf");
+ } else {
+ m_hdr = m[i];
+ }
+ }
+
+ if (off != len)
+ GOTO_FAIL("Invalid segs");
+
+ packet_type = rte_net_get_ptype(m_hdr, &hdr_lens, RTE_PTYPE_ALL_MASK);
+ l3 = packet_type & RTE_PTYPE_L3_MASK;
+
+ l3_hdr = rte_pktmbuf_mtod_offset(m_hdr, void *, hdr_lens.l2_len);
+ off = hdr_lens.l2_len + hdr_lens.l3_len;
+
+ if (l3 == RTE_PTYPE_L3_IPV4 || l3 == RTE_PTYPE_L3_IPV4_EXT) {
+ if (rte_ipv4_udptcp_cksum_mbuf_verify(m_hdr, l3_hdr, off) != 0)
+ GOTO_FAIL("Invalid L4 checksum verification for multiple mbufs");
+ } else if (l3 == RTE_PTYPE_L3_IPV6 || l3 == RTE_PTYPE_L3_IPV6_EXT) {
+ if (rte_ipv6_udptcp_cksum_mbuf_verify(m_hdr, l3_hdr, off) != 0)
+ GOTO_FAIL("Invalid L4 checksum verification for multiple mbufs");
+ }
+
+ for (i = 0; i < segs_len; i++)
+ rte_pktmbuf_free(m[i]);
+
+ return 0;
+
+fail:
+ for (i = 0; i < segs_len; i++) {
+ if (m[i])
+ rte_pktmbuf_free(m[i]);
+ }
+
+ return -1;
+}
+
static int
test_cksum(void)
{
@@ -256,6 +354,12 @@ test_cksum(void)
sizeof(test_cksum_ipv4_opts_udp)) < 0)
GOTO_FAIL("checksum error on ipv4_opts_udp");
+ if (test_l4_cksum_multi_mbufs(pktmbuf_pool, test_cksum_ipv4_tcp_multi_segs,
+ sizeof(test_cksum_ipv4_tcp_multi_segs),
+ test_cksum_ipv4_tcp_multi_segs_len,
+ sizeof(test_cksum_ipv4_tcp_multi_segs_len)) < 0)
+ GOTO_FAIL("checksum error on multi mbufs check");
+
rte_mempool_free(pktmbuf_pool);
return 0;
diff --git a/lib/net/rte_cksum.h b/lib/net/rte_cksum.h
index a8e8927952..aa584d5f8d 100644
--- a/lib/net/rte_cksum.h
+++ b/lib/net/rte_cksum.h
@@ -80,6 +80,25 @@ __rte_raw_cksum_reduce(uint32_t sum)
return (uint16_t)sum;
}
+/**
+ * @internal Reduce a sum to the non-complemented checksum.
+ * Helper routine for the rte_raw_cksum_mbuf().
+ *
+ * @param sum
+ * Value of the sum.
+ * @return
+ * The non-complemented checksum.
+ */
+static inline uint16_t
+__rte_raw_cksum_reduce_u64(uint64_t sum)
+{
+ uint32_t tmp;
+
+ tmp = __rte_raw_cksum_reduce((uint32_t)sum);
+ tmp += __rte_raw_cksum_reduce((uint32_t)(sum >> 32));
+ return __rte_raw_cksum_reduce(tmp);
+}
+
/**
* Process the non-complemented checksum of a buffer.
*
@@ -119,8 +138,9 @@ rte_raw_cksum_mbuf(const struct rte_mbuf *m,
uint32_t off, uint32_t len,
{
const struct rte_mbuf *seg;
const char *buf;
- uint32_t sum, tmp;
+ uint32_t tmp;
uint32_t seglen, done;
+ uint64_t sum;
/* easy case: all data in the first segment */
if (off + len <= rte_pktmbuf_data_len(m)) {
@@ -157,7 +177,7 @@ rte_raw_cksum_mbuf(const struct rte_mbuf *m,
uint32_t off, uint32_t len,
for (;;) {
tmp = __rte_raw_cksum(buf, seglen, 0);
if (done & 1)
- tmp = rte_bswap16((uint16_t)tmp);
+ tmp = rte_bswap32(tmp);
sum += tmp;
done += seglen;
if (done == len)
@@ -169,7 +189,7 @@ rte_raw_cksum_mbuf(const struct rte_mbuf *m,
uint32_t off, uint32_t len,
seglen = len - done;
}
- *cksum = __rte_raw_cksum_reduce(sum);
+ *cksum = __rte_raw_cksum_reduce_u64(sum);
return 0;
}
--
2.39.2 (Apple Git-143)
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