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Validate no-packet Extended Procedure parsing #541

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5eab599
Validate OTAR TLV lengths before parsing
sylvesterkaczmarek Sep 9, 2026
b668bdc
Parse no-packet Extended Procedure reply type
sylvesterkaczmarek Sep 9, 2026
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20 changes: 17 additions & 3 deletions src/core/crypto.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1219,17 +1219,31 @@ int32_t Crypto_Process_Extended_Procedure_Pdu(TC_t *tc_sdls_processed_frame, uin
#endif
// No Packet HDR or PUS in these frames
// SDLS TLV PDU
sdls_frame.hdr.type = (tc_sdls_processed_frame->tc_pdu[0] & 0x80) >> 7;
sdls_frame.tlv_pdu.hdr.type = (tc_sdls_processed_frame->tc_pdu[0] & 0x80) >> 7;
sdls_frame.tlv_pdu.hdr.uf = (tc_sdls_processed_frame->tc_pdu[0] & 0x40) >> 6;
sdls_frame.tlv_pdu.hdr.sg = (tc_sdls_processed_frame->tc_pdu[0] & 0x30) >> 4;
sdls_frame.tlv_pdu.hdr.pid = (tc_sdls_processed_frame->tc_pdu[0] & 0x0F);
sdls_frame.tlv_pdu.hdr.pdu_len =
(tc_sdls_processed_frame->tc_pdu[1] << 8) | tc_sdls_processed_frame->tc_pdu[2];
for (int x = 3; x < (3 + tc_sdls_processed_frame->tc_header.fl); x++)

if (tc_sdls_processed_frame->tc_pdu_len < SDLS_TLV_HDR_SIZE)
{
return CRYPTO_LIB_ERR_BAD_TLV_LENGTH;
}

uint16_t max_tlv = tc_sdls_processed_frame->tc_pdu_len - SDLS_TLV_HDR_SIZE;
uint16_t declared_tlv_bytes =
(sdls_frame.tlv_pdu.hdr.pdu_len + (BYTE_LEN - 1)) / BYTE_LEN;
if ((declared_tlv_bytes > max_tlv) || (declared_tlv_bytes > TLV_DATA_SIZE))
{
return CRYPTO_LIB_ERR_BAD_TLV_LENGTH;
}

for (uint16_t x = 0; x < declared_tlv_bytes; x++)
{
// Todo - Consider how this behaves with large OTAR PDUs that are larger than 1 TC in size. Most
// likely fails. Must consider Uplink Sessions (sequence numbers).
sdls_frame.tlv_pdu.data[x - 3] = tc_sdls_processed_frame->tc_pdu[x];
sdls_frame.tlv_pdu.data[x] = tc_sdls_processed_frame->tc_pdu[x + SDLS_TLV_HDR_SIZE];
}

#ifdef CCSDS_DEBUG
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26 changes: 18 additions & 8 deletions src/core/crypto_key_mgmt.c
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Expand Up @@ -54,20 +54,30 @@ int32_t Crypto_Key_OTAR(void)
int y;
int32_t status = CRYPTO_LIB_SUCCESS;

int pdu_keys = ((sdls_frame.tlv_pdu.hdr.pdu_len / BYTE_LEN) - SDLS_KEYID_LEN - SDLS_IV_LEN - MAC_SIZE) /
(SDLS_KEYID_LEN + SDLS_KEY_LEN);
const int pdu_len_bits = sdls_frame.tlv_pdu.hdr.pdu_len;
const int pdu_len_bytes = pdu_len_bits / BYTE_LEN;
const int fixed_len = SDLS_KEYID_LEN + SDLS_IV_LEN + MAC_SIZE;
const int key_block_len = SDLS_KEYID_LEN + SDLS_KEY_LEN;

if ((pdu_len_bits % BYTE_LEN != 0) || (pdu_len_bytes < fixed_len) || (pdu_len_bytes > TLV_DATA_SIZE) ||
((pdu_len_bytes - fixed_len) % key_block_len != 0))
{
return CRYPTO_LIB_ERR_OTAR_BAD_TLV_LENGTH;
}

int pdu_keys = (pdu_len_bytes - fixed_len) / key_block_len;
if (pdu_keys > SDLS_EKB_LEN)
{
return CRYPTO_LIB_ERR_OTAR_BAD_TLV_LENGTH;
}

int w;
crypto_key_t *ekp = NULL;

#ifdef DEBUG
int expected_pdu_len = SDLS_KEYID_LEN + SDLS_IV_LEN + ((SDLS_KEYID_LEN + SDLS_KEY_LEN) * pdu_keys) + MAC_SIZE;
int expected_pdu_len = fixed_len + (key_block_len * pdu_keys);
printf("Expected PDU Length: %d (%d keys)\n", expected_pdu_len, pdu_keys);
#endif
if ((sdls_frame.tlv_pdu.hdr.pdu_len / BYTE_LEN) <
SDLS_KEYID_LEN + SDLS_IV_LEN + ((SDLS_KEYID_LEN + SDLS_KEY_LEN) * pdu_keys) + MAC_SIZE)
{
return CRYPTO_LIB_ERR_OTAR_BAD_TLV_LENGTH;
}

// Master Key ID
packet.mkid = (sdls_frame.tlv_pdu.data[0] << BYTE_LEN) | (sdls_frame.tlv_pdu.data[1]);
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47 changes: 40 additions & 7 deletions test/unit/ut_crypto.c
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Expand Up @@ -269,19 +269,52 @@ UTEST(CRYPTO_C, PDU_SWITCH)
/**
* @brief Unit Test: Crypto Extended Procedures PDU Test
**/
/**
* @brief Unit Test: No-packet EP reply type is parsed into the TLV header
**/
UTEST(CRYPTO_C, EXT_PROC_PDU_NO_PACKET_REPLY_TYPE)
{
TC_t tc_frame = {0};

tc_frame.tc_sec_header.spi = SPI_MIN;
tc_frame.tc_header.vcid = TC_SDLS_EP_VCID;
tc_frame.tc_pdu_len = SDLS_TLV_HDR_SIZE;
tc_frame.tc_pdu[0] = 0x80; // Procedure type = reply

sdls_frame.tlv_pdu.hdr.type = PDU_TYPE_COMMAND;

int32_t status = Crypto_Process_Extended_Procedure_Pdu(&tc_frame, NULL, 0);
ASSERT_EQ(CRYPTO_LIB_SUCCESS, status);
ASSERT_EQ(PDU_TYPE_REPLY, (uint8_t)sdls_frame.tlv_pdu.hdr.type);
}

UTEST(CRYPTO_C, EXT_PROC_PDU_REJECTS_OVERSIZED_DECLARED_TLV)
{
TC_t tc_frame = {0};

tc_frame.tc_sec_header.spi = SPI_MIN;
tc_frame.tc_header.vcid = TC_SDLS_EP_VCID;
tc_frame.tc_pdu_len = SDLS_TLV_HDR_SIZE + 4;
tc_frame.tc_pdu[0] = PID_OTAR;
tc_frame.tc_pdu[1] = 0;
tc_frame.tc_pdu[2] = 64; // Declares eight bytes, but only four are present.

int32_t status = Crypto_Process_Extended_Procedure_Pdu(&tc_frame, NULL, tc_frame.tc_pdu_len);
ASSERT_EQ(CRYPTO_LIB_ERR_BAD_TLV_LENGTH, status);
}

UTEST(CRYPTO_C, EXT_PROC_PDU)
{
remove("sa_save_file.bin");
uint8_t *ingest = NULL;
TC_t *tc_frame = NULL;
tc_frame = malloc(sizeof(uint8_t) * TC_SIZE);
int32_t status = CRYPTO_LIB_ERROR;
TC_t tc_frame = {0};
int32_t status = CRYPTO_LIB_ERROR;
crypto_config_tc.has_pus_hdr = TC_NO_PUS_HDR;
tc_frame->tc_header.vcid = TC_SDLS_EP_VCID;
tc_frame->tc_header.fl = 1;
tc_frame.tc_sec_header.spi = SPI_MIN;
tc_frame.tc_header.vcid = TC_SDLS_EP_VCID;
tc_frame.tc_pdu_len = SDLS_TLV_HDR_SIZE;

status = Crypto_Process_Extended_Procedure_Pdu(tc_frame, ingest, TC_SIZE);
free(tc_frame);
status = Crypto_Process_Extended_Procedure_Pdu(&tc_frame, ingest, TC_SIZE);
ASSERT_EQ(status, CRYPTO_LIB_SUCCESS);
}
#endif // CRYPTO_EPROC
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6 changes: 6 additions & 0 deletions test/unit/ut_ep_key_mgmt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,12 @@
#include "sa_interface.h"
#include "utest.h"

UTEST(EP_KEY_MGMT, OTAR_REJECTS_OVERSIZED_TLV)
{
sdls_frame.tlv_pdu.hdr.pdu_len = (TLV_DATA_SIZE + 1) * BYTE_LEN;
ASSERT_EQ(CRYPTO_LIB_ERR_OTAR_BAD_TLV_LENGTH, Crypto_Key_OTAR());
}

UTEST(EP_KEY_MGMT, OTAR_0_140_142)
{
remove("sa_save_file.bin");
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