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Handle set_alpn_protos inputs better.

Browse Source 
It's possible to set an invalid protocol list that will be sent in a
ClientHello. This validates the inputs to make sure this does not
happen.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14815)
This commit is contained in:
Todd Short 2021-03-22 12:56:36 -04:00 committed by Tomas Mraz
parent 3ab736acb8
commit feba11cf2e
3 changed files with 124 additions and 9 deletions
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49
ssl/ssl_lib.c
View File

@ -2985,6 +2985,19 @@ void SSL_CTX_set_npn_select_cb(SSL_CTX *ctx,
}
#endif
static int alpn_value_ok(const unsigned char *protos, unsigned int protos_len)
{
unsigned int idx;
if (protos_len < 2 || protos == NULL)
return 0;
for (idx = 0; idx < protos_len; idx += protos[idx] + 1) {
if (protos[idx] == 0)
return 0;
}
return idx == protos_len;
}
/*
* SSL_CTX_set_alpn_protos sets the ALPN protocol list on |ctx| to |protos|.
* |protos| must be in wire-format (i.e. a series of non-empty, 8-bit
@ -2993,13 +3006,25 @@ void SSL_CTX_set_npn_select_cb(SSL_CTX *ctx,
int SSL_CTX_set_alpn_protos(SSL_CTX *ctx, const unsigned char *protos,
unsigned int protos_len)
{
OPENSSL_free(ctx->ext.alpn);
ctx->ext.alpn = OPENSSL_memdup(protos, protos_len);
if (ctx->ext.alpn == NULL) {
unsigned char *alpn;
if (protos_len == 0 || protos == NULL) {
OPENSSL_free(ctx->ext.alpn);
ctx->ext.alpn = NULL;
ctx->ext.alpn_len = 0;
return 0;
}
/* Not valid per RFC */
if (!alpn_value_ok(protos, protos_len))
return 1;
alpn = OPENSSL_memdup(protos, protos_len);
if (alpn == NULL) {
ERR_raise(ERR_LIB_SSL, ERR_R_MALLOC_FAILURE);
return 1;
}
OPENSSL_free(ctx->ext.alpn);
ctx->ext.alpn = alpn;
ctx->ext.alpn_len = protos_len;
return 0;
@ -3013,13 +3038,25 @@ int SSL_CTX_set_alpn_protos(SSL_CTX *ctx, const unsigned char *protos,
int SSL_set_alpn_protos(SSL *ssl, const unsigned char *protos,
unsigned int protos_len)
{
OPENSSL_free(ssl->ext.alpn);
ssl->ext.alpn = OPENSSL_memdup(protos, protos_len);
if (ssl->ext.alpn == NULL) {
unsigned char *alpn;
if (protos_len == 0 || protos == NULL) {
OPENSSL_free(ssl->ext.alpn);
ssl->ext.alpn = NULL;
ssl->ext.alpn_len = 0;
return 0;
}
/* Not valid per RFC */
if (!alpn_value_ok(protos, protos_len))
return 1;
alpn = OPENSSL_memdup(protos, protos_len);
if (alpn == NULL) {
ERR_raise(ERR_LIB_SSL, ERR_R_MALLOC_FAILURE);
return 1;
}
OPENSSL_free(ssl->ext.alpn);
ssl->ext.alpn = alpn;
ssl->ext.alpn_len = protos_len;
return 0;

12
test/clienthellotest.c
View File

@ -45,10 +45,16 @@
static const char *sessionfile = NULL;
/* Dummy ALPN protocols used to pad out the size of the ClientHello */
/* ASCII 'O' = 79 = 0x4F = EBCDIC '|'*/
#ifdef CHARSET_EBCDIC
static const char alpn_prots[] =
"0123456789012345678901234567890123456789012345678901234567890123456789"
"0123456789012345678901234567890123456789012345678901234567890123456789"
"01234567890123456789";
"|1234567890123456789012345678901234567890123456789012345678901234567890123456789"
"|1234567890123456789012345678901234567890123456789012345678901234567890123456789";
#else
static const char alpn_prots[] =
"O1234567890123456789012345678901234567890123456789012345678901234567890123456789"
"O1234567890123456789012345678901234567890123456789012345678901234567890123456789";
#endif
static int test_client_hello(int currtest)
{

72
test/sslapitest.c
View File

@ -8616,6 +8616,77 @@ end:
return testresult;
}
#endif
/*
* Test that setting an ALPN does not violate RFC
*/
static int test_set_alpn(void)
{
SSL_CTX *ctx = NULL;
SSL *ssl = NULL;
int testresult = 0;
unsigned char bad0[] = { 0x00, 'b', 'a', 'd' };
unsigned char good[] = { 0x04, 'g', 'o', 'o', 'd' };
unsigned char bad1[] = { 0x01, 'b', 'a', 'd' };
unsigned char bad2[] = { 0x03, 'b', 'a', 'd', 0x00};
unsigned char bad3[] = { 0x03, 'b', 'a', 'd', 0x01, 'b', 'a', 'd'};
unsigned char bad4[] = { 0x03, 'b', 'a', 'd', 0x06, 'b', 'a', 'd'};
/* Create an initial SSL_CTX with no certificate configured */
ctx = SSL_CTX_new_ex(libctx, NULL, TLS_server_method());
if (!TEST_ptr(ctx))
goto end;
/* the set_alpn functions return 0 (false) on success, non-zero (true) on failure */
if (!TEST_false(SSL_CTX_set_alpn_protos(ctx, NULL, 2)))
goto end;
if (!TEST_false(SSL_CTX_set_alpn_protos(ctx, good, 0)))
goto end;
if (!TEST_false(SSL_CTX_set_alpn_protos(ctx, good, sizeof(good))))
goto end;
if (!TEST_true(SSL_CTX_set_alpn_protos(ctx, good, 1)))
goto end;
if (!TEST_true(SSL_CTX_set_alpn_protos(ctx, bad0, sizeof(bad0))))
goto end;
if (!TEST_true(SSL_CTX_set_alpn_protos(ctx, bad1, sizeof(bad1))))
goto end;
if (!TEST_true(SSL_CTX_set_alpn_protos(ctx, bad2, sizeof(bad2))))
goto end;
if (!TEST_true(SSL_CTX_set_alpn_protos(ctx, bad3, sizeof(bad3))))
goto end;
if (!TEST_true(SSL_CTX_set_alpn_protos(ctx, bad4, sizeof(bad4))))
goto end;
ssl = SSL_new(ctx);
if (!TEST_ptr(ssl))
goto end;
if (!TEST_false(SSL_set_alpn_protos(ssl, NULL, 2)))
goto end;
if (!TEST_false(SSL_set_alpn_protos(ssl, good, 0)))
goto end;
if (!TEST_false(SSL_set_alpn_protos(ssl, good, sizeof(good))))
goto end;
if (!TEST_true(SSL_set_alpn_protos(ssl, good, 1)))
goto end;
if (!TEST_true(SSL_set_alpn_protos(ssl, bad0, sizeof(bad0))))
goto end;
if (!TEST_true(SSL_set_alpn_protos(ssl, bad1, sizeof(bad1))))
goto end;
if (!TEST_true(SSL_set_alpn_protos(ssl, bad2, sizeof(bad2))))
goto end;
if (!TEST_true(SSL_set_alpn_protos(ssl, bad3, sizeof(bad3))))
goto end;
if (!TEST_true(SSL_set_alpn_protos(ssl, bad4, sizeof(bad4))))
goto end;
testresult = 1;
end:
SSL_free(ssl);
SSL_CTX_free(ctx);
return testresult;
}
static int test_inherit_verify_param(void)
{
@ -8908,6 +8979,7 @@ int setup_tests(void)
ADD_TEST(test_sni_tls13);
#endif
ADD_TEST(test_inherit_verify_param);
ADD_TEST(test_set_alpn);
return 1;
err: