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test-tool: add iSCSICHAP.Base64Oversize test

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This is very similar to the previous Base64 CHAP test, except we
intentionally inject extra base64 characters into the CHAP_R field.
This should cause login to fail. On LIO this can trigger a buffer
overwrite reported at:
https://lore.kernel.org/target-devel/6a0a00f2.e1ea9722.1dc845.b85e@mx.google.com/

Signed-off-by: David Disseldorp <ddiss@suse.de>
This commit is contained in:
David Disseldorp
2026-05-22 00:17:18 +10:00
parent 311548e860
commit 1bdec140a7
3 changed files with 93 additions and 0 deletions
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1
test-tool/iscsi-test-cu.c
View File

@@ -589,6 +589,7 @@ static CU_TestInfo tests_iscsi_chap[] = {
{ "Invalid", test_iscsi_chap_invalid },
#ifdef HAVE_LIBGNUTLS
{ "Base64", test_iscsi_chap_base64 },
{ "Base64Oversize", test_iscsi_chap_base64_oversize },
#endif
CU_TEST_INFO_NULL
};

1
test-tool/iscsi-test-cu.h
View File

@@ -89,6 +89,7 @@ void test_iscsi_chap_simple(void);
void test_iscsi_chap_invalid(void);
#ifdef HAVE_LIBGNUTLS
void test_iscsi_chap_base64(void);
void test_iscsi_chap_base64_oversize(void);
#endif
void test_mandatory_sbc(void);

91
test-tool/test_iscsi_chap_base64.c
View File

@@ -216,3 +216,94 @@ test_iscsi_chap_base64(void)
ret = test_iscsi_chap_login(chap_r_mod_b64_replace_queue);
CU_ASSERT_EQUAL(ret, 0);
}
static void
chap_r_mod_b64_oversize_replace_queue(struct iscsi_context *iscsi, struct iscsi_pdu *pdu)
{
int ret;
char *chap_r_str = NULL;
size_t chap_r_strlen;
char *kv_buf = NULL;
gnutls_datum_t hex;
gnutls_datum_t bin;
gnutls_datum_t b64;
if ((pdu->outdata.data[0] & 0x3f) != ISCSI_PDU_LOGIN_REQUEST) {
goto out;
}
ret = test_iscsi_strip_tag(iscsi, pdu, "CHAP_R=", &chap_r_str);
if (ret == -ENOENT) {
logging(LOG_VERBOSE, "ignoring login PDU without CHAP_R");
goto out;
}
if (ret < 0) {
return;
}
logging(LOG_VERBOSE, "CHAP_R=%s converting to base64", chap_r_str);
chap_r_strlen = strlen(chap_r_str);
if (chap_r_strlen < 2 ||
(chap_r_str[0] != '0' ||
(chap_r_str[1] != 'x' && chap_r_str[1] != 'X'))) {
CU_FAIL("unexpected CHAP_R hex prefix from libiscsi");
free(chap_r_str);
goto out;
}
hex = (gnutls_datum_t){
.data = (void *)(chap_r_str + 2),
.size = strlen(chap_r_str + 2),
};
ret = gnutls_hex_decode2(&hex, &bin);
free(chap_r_str);
if (ret < 0) {
CU_FAIL("gnutls_hex_decode2() failed");
goto out;
}
ret = gnutls_base64_encode2(&bin, &b64);
gnutls_free(bin.data);
if (ret < 0) {
CU_FAIL("gnutls_base64_encode2() failed");
goto out;
}
/* inject an extra base64-valid prefix */
kv_buf = malloc(sizeof("CHAP_R=0bb3ZlcnNpemUK") + b64.size);
/* nulterm space from sizeof(), doesn't matter if @b64 includes it */
sprintf(kv_buf, "CHAP_R=0bb3ZlcnNpemUK%.*s", b64.size, b64.data);
gnutls_free(b64.data);
ret = iscsi_pdu_add_data(iscsi, pdu, (const unsigned char *)kv_buf,
strlen(kv_buf) + 1);
logging(LOG_VERBOSE, "replaced Login PDU CHAP_R with %s", kv_buf);
free(kv_buf);
if (ret < 0) {
return;
}
out:
orig_queue_pdu(iscsi, pdu);
}
void
test_iscsi_chap_base64_oversize(void)
{
int ret;
logging(LOG_VERBOSE, LOG_BLANK_LINE);
logging(LOG_VERBOSE, "Test CHAP_C base64 oversize values");
CHECK_FOR_ISCSI(sd);
if (sd->iscsi_ctx->chap_a != 5) {
const char *err = "[SKIPPED] This test requires "
"an iSCSI session with CHAP_A=5";
logging(LOG_NORMAL, "%s", err);
CU_PASS(err);
return;
}
ret = test_iscsi_chap_login(chap_r_mod_b64_oversize_replace_queue);
CU_ASSERT_NOT_EQUAL(ret, 0);
}