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Merged
danielinux merged 2 commits into from
Mar 14, 2026
Merged

esp: improve oseq overflow handling. #80

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556da5e
esp: improve oseq overflow handling.
philljj Mar 14, 2026
539cb62
esp: detect multiple subsequent seq overflows.
philljj Mar 14, 2026
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50 changes: 50 additions & 0 deletions src/test/unit/unit_esp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -503,6 +503,55 @@ START_TEST(test_replay_old_seqs_after_jump)
}
END_TEST

/* The transmitted sequence number must never be allowed to overflow. */
START_TEST(test_replay_overflow)
{
static uint8_t buf[LINK_MTU + 256];
uint8_t ref[64];
uint32_t frame_len, i;
uint16_t ip_len;
int ret;
wolfIP_esp_sa * esp_sa = NULL;
struct wolfIP_ip_packet *ip = (struct wolfIP_ip_packet *)buf;

for (i = 0U; i < sizeof(ref); i++) ref[i] = (uint8_t)(i & 0xFFU);

esp_setup();

ret = wolfIP_esp_sa_new_gcm(0, (uint8_t *)spi_rt,
atoip4(T_SRC), atoip4(T_DST),
ESP_ENC_GCM_RFC4543,
(uint8_t *)k_aes256_gcm,
sizeof(k_aes256_gcm));
ck_assert_int_eq(ret, 0);
esp_sa = esp_sa_get(0, (uint8_t *)spi_rt);
ck_assert_ptr_nonnull(esp_sa);

/* Set oseq to 10 before overflow. */
esp_sa->replay.oseq = (ESP_MAX_32_SEQ - 10);

/* all of these should be ok. */
for (i = 0; i < 10; ++i) {
frame_len = build_ip_packet(buf, sizeof(buf), WI_IPPROTO_UDP,
ref, sizeof(ref));
ip_len = (uint16_t)(frame_len - ETH_HEADER_LEN);

ret = esp_transport_wrap(ip, &ip_len);
ck_assert_int_eq(ret, 0);
}

/* all of these should be rejected, oseq overflow is detected. */
for (i = 0; i < 10; ++i) {
frame_len = build_ip_packet(buf, sizeof(buf), WI_IPPROTO_UDP,
ref, sizeof(ref));
ip_len = (uint16_t)(frame_len - ETH_HEADER_LEN);

ret = esp_transport_wrap(ip, &ip_len);
ck_assert_int_eq(ret, -1);
}
}
END_TEST

/*
* esp_transport_unwrap error paths
*/
Expand Down Expand Up @@ -1123,6 +1172,7 @@ static Suite *esp_suite(void)
tcase_add_test(tc, test_replay_low_hi_seq_accepts_seq_one);
tcase_add_test(tc, test_replay_jump_resets_bitmap);
tcase_add_test(tc, test_replay_old_seqs_after_jump);
tcase_add_test(tc, test_replay_overflow);
suite_add_tcase(s, tc);

/* Unwrap error paths */
Expand Down
7 changes: 6 additions & 1 deletion src/wolfesp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1489,10 +1489,15 @@ esp_transport_wrap(struct wolfIP_ip_packet *ip, uint16_t * ip_len)
memcpy(payload, esp_sa->spi, sizeof(esp_sa->spi));
payload += ESP_SPI_LEN;

esp_sa->replay.oseq++;
if (esp_sa->replay.oseq == 0) {
esp_sa->replay.oseq--;
ESP_LOG("error: oseq overflow\n");
return -1;
}
seq_n = ee32(esp_sa->replay.oseq);
memcpy(payload, &seq_n, sizeof(seq_n));
payload += ESP_SEQ_LEN;
esp_sa->replay.oseq++;

if (iv_len) {
/* skip iv field, will generate later. */
Expand Down
2 changes: 1 addition & 1 deletion wolfesp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -69,7 +69,7 @@ typedef struct replay_t replay_t;
do { \
(r).bitmap = 0U; \
(r).hi_seq = ESP_REPLAY_WIN; \
(r).oseq = 1U; \
(r).oseq = 0U; \
} while (0)

/* Minimal ESP Security Association structure.
Expand Down
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