[git commit] tls: add the i/o loop - largish rework of i/o buffering
Denys Vlasenko
vda.linux at googlemail.com
Fri Jan 20 02:15:09 UTC 2017
commit: https://git.busybox.net/busybox/commit/?id=abbf17abccbf832365d9acf1c280369ba7d5f8b2
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
networking/tls.c | 274 +++++++++++++++++++++++++++++++++----------------------
1 file changed, 166 insertions(+), 108 deletions(-)
diff --git a/networking/tls.c b/networking/tls.c
index 0927358..71be2de 100644
--- a/networking/tls.c
+++ b/networking/tls.c
@@ -23,9 +23,10 @@
//usage:#define tls_full_usage "\n\n"
#include "tls.h"
+#include "common_bufsiz.h"
#define TLS_DEBUG 1
-#define TLS_DEBUG_HASH 0
+#define TLS_DEBUG_HASH 1
#define TLS_DEBUG_DER 0
#if TLS_DEBUG
@@ -150,9 +151,8 @@
// works against "openssl s_server -cipher NULL"
// and against wolfssl-3.9.10-stable/examples/server/server.c:
//#define CIPHER_ID TLS_RSA_WITH_NULL_SHA256 // for testing (does everything except encrypting)
-// "works", meaning
-// "can send encrypted FINISHED to wolfssl-3.9.10-stable/examples/server/server.c",
-// don't yet read its encrypted answers:
+// works against wolfssl-3.9.10-stable/examples/server/server.c
+// (getting back and decrypt ok first application data message)
#define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // ok, no SERVER_KEY_EXCHANGE
enum {
@@ -162,6 +162,11 @@ enum {
AES_BLOCKSIZE = 16,
AES128_KEYSIZE = 16,
AES256_KEYSIZE = 32,
+
+ MAX_TLS_RECORD = (1 << 14),
+ OUTBUF_PFX = 8 + AES_BLOCKSIZE, /* header + IV */
+ OUTBUF_SFX = SHA256_OUTSIZE + AES_BLOCKSIZE, /* MAC + padding */
+ MAX_OTBUF = MAX_TLS_RECORD - OUTBUF_PFX - OUTBUF_SFX,
};
struct record_hdr {
@@ -195,6 +200,9 @@ typedef struct tls_state {
// exceed 2^64-1.
uint64_t write_seq64_be;
+ int outbuf_size;
+ uint8_t *outbuf;
+
// RFC 5246
// |6.2.1. Fragmentation
// | The record layer fragments information blocks into TLSPlaintext
@@ -225,7 +233,6 @@ typedef struct tls_state {
//needed?
uint64_t align____;
uint8_t inbuf[20*1024];
- uint8_t outbuf[20*1024];
} tls_state_t;
@@ -462,6 +469,17 @@ static void tls_error_die(tls_state_t *tls)
xfunc_die();
}
+static void *tls_get_outbuf(tls_state_t *tls, int len)
+{
+ if (len > MAX_OTBUF)
+ xfunc_die();
+ if (tls->outbuf_size < len + OUTBUF_PFX + OUTBUF_SFX) {
+ tls->outbuf_size = len + OUTBUF_PFX + OUTBUF_SFX;
+ tls->outbuf = xrealloc(tls->outbuf, tls->outbuf_size);
+ }
+ return tls->outbuf + OUTBUF_PFX;
+}
+
// RFC 5246
// 6.2.3.1. Null or Standard Stream Cipher
//
@@ -501,39 +519,41 @@ static void tls_error_die(tls_state_t *tls)
// -------- ----------- ---------- --------------
// SHA HMAC-SHA1 20 20
// SHA256 HMAC-SHA256 32 32
-static void xwrite_and_hash(tls_state_t *tls, /*const*/ void *buf, unsigned size)
+static void xwrite_encrypted(tls_state_t *tls, unsigned size, unsigned type)
{
- uint8_t mac_hash[SHA256_OUTSIZE];
- struct record_hdr *xhdr = buf;
+ uint8_t *buf = tls->outbuf + OUTBUF_PFX;
+ struct record_hdr *xhdr;
- if (!tls->encrypt_on_write) {
- xwrite(tls->fd, buf, size);
- dbg("wrote %u bytes\n", size);
- /* Handshake hash does not include record headers */
- if (size > 5 && xhdr->type == RECORD_TYPE_HANDSHAKE) {
- sha256_hash_dbg(">> sha256:%s", &tls->handshake_sha256_ctx, (uint8_t*)buf + 5, size - 5);
- }
- return;
- }
+ xhdr = (void*)(buf - sizeof(*xhdr));
+ if (CIPHER_ID != TLS_RSA_WITH_NULL_SHA256)
+ xhdr = (void*)(buf - sizeof(*xhdr) - AES_BLOCKSIZE); /* place for IV */
+
+ xhdr->type = type;
+ xhdr->proto_maj = TLS_MAJ;
+ xhdr->proto_min = TLS_MIN;
+ /* fake unencrypted record header len for MAC calculation */
+ xhdr->len16_hi = size >> 8;
+ xhdr->len16_lo = size & 0xff;
+ /* Calculate MAC signature */
//TODO: convert hmac_sha256 to precomputed
- hmac_sha256(mac_hash,
+ hmac_sha256(buf + size,
tls->client_write_MAC_key, sizeof(tls->client_write_MAC_key),
&tls->write_seq64_be, sizeof(tls->write_seq64_be),
+ xhdr, sizeof(*xhdr),
buf, size,
NULL);
tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(tls->write_seq64_be));
+ size += SHA256_OUTSIZE;
+
if (CIPHER_ID == TLS_RSA_WITH_NULL_SHA256) {
/* No encryption, only signing */
- xhdr->len16_lo += SHA256_OUTSIZE;
-//FIXME: overflow into len16_hi?
- xwrite(tls->fd, buf, size);
- xhdr->len16_lo -= SHA256_OUTSIZE;
- dbg("wrote %u bytes\n", size);
-
- xwrite(tls->fd, mac_hash, sizeof(mac_hash));
- dbg("wrote %u bytes of hash\n", (int)sizeof(mac_hash));
+ xhdr->len16_hi = size >> 8;
+ xhdr->len16_lo = size & 0xff;
+ dump_hex(">> %s\n", xhdr, sizeof(*xhdr) + size);
+ xwrite(tls->fd, xhdr, sizeof(*xhdr) + size);
+ dbg("wrote %u bytes (NULL crypt, SHA256 hash)\n", size);
return;
}
@@ -579,13 +599,8 @@ static void xwrite_and_hash(tls_state_t *tls, /*const*/ void *buf, unsigned size
uint8_t padding_length;
/* Build IV+content+MAC+padding in outbuf */
- tls_get_random(tls->outbuf, AES_BLOCKSIZE); /* IV */
- p = tls->outbuf + AES_BLOCKSIZE;
- size -= sizeof(*xhdr);
- dbg("before crypt: 5 hdr + %u data + %u hash bytes\n", size, (int)sizeof(mac_hash));
- p = mempcpy(p, buf + sizeof(*xhdr), size); /* content */
- p = mempcpy(p, mac_hash, sizeof(mac_hash)); /* MAC */
- size += sizeof(mac_hash);
+ tls_get_random(buf - AES_BLOCKSIZE, AES_BLOCKSIZE); /* IV */
+ dbg("before crypt: 5 hdr + %u data + %u hash bytes\n", size, SHA256_OUTSIZE);
// RFC is talking nonsense:
// Padding that is added to force the length of the plaintext to be
// an integral multiple of the block cipher's block length.
@@ -601,6 +616,7 @@ static void xwrite_and_hash(tls_state_t *tls, /*const*/ void *buf, unsigned size
// If you need no bytes to reach BLOCKSIZE, you have to pad a full
// BLOCKSIZE with bytes of value (BLOCKSIZE-1).
// It's ok to have more than minimum padding, but we do minimum.
+ p = buf + size;
padding_length = (~size) & (AES_BLOCKSIZE - 1);
do {
*p++ = padding_length; /* padding */
@@ -608,12 +624,12 @@ static void xwrite_and_hash(tls_state_t *tls, /*const*/ void *buf, unsigned size
} while ((size & (AES_BLOCKSIZE - 1)) != 0);
/* Encrypt content+MAC+padding in place */
- psAesInit(&ctx, tls->outbuf, /* IV */
+ psAesInit(&ctx, buf - AES_BLOCKSIZE, /* IV */
tls->client_write_key, sizeof(tls->client_write_key)
);
psAesEncrypt(&ctx,
- tls->outbuf + AES_BLOCKSIZE, /* plaintext */
- tls->outbuf + AES_BLOCKSIZE, /* ciphertext */
+ buf, /* plaintext */
+ buf, /* ciphertext */
size
);
@@ -623,14 +639,33 @@ static void xwrite_and_hash(tls_state_t *tls, /*const*/ void *buf, unsigned size
size += AES_BLOCKSIZE; /* + IV */
xhdr->len16_hi = size >> 8;
xhdr->len16_lo = size & 0xff;
- xwrite(tls->fd, xhdr, sizeof(*xhdr));
- xwrite(tls->fd, tls->outbuf, size);
+ dump_hex(">> %s\n", xhdr, sizeof(*xhdr) + size);
+ xwrite(tls->fd, xhdr, sizeof(*xhdr) + size);
dbg("wrote %u bytes\n", (int)sizeof(*xhdr) + size);
-//restore xhdr->len16_hi = ;
-//restore xhdr->len16_lo = ;
}
}
+static void xwrite_and_update_handshake_hash(tls_state_t *tls, unsigned size)
+{
+ if (!tls->encrypt_on_write) {
+ uint8_t *buf = tls->outbuf + OUTBUF_PFX;
+ struct record_hdr *xhdr = (void*)(buf - sizeof(*xhdr));
+
+ xhdr->type = RECORD_TYPE_HANDSHAKE;
+ xhdr->proto_maj = TLS_MAJ;
+ xhdr->proto_min = TLS_MIN;
+ xhdr->len16_hi = size >> 8;
+ xhdr->len16_lo = size & 0xff;
+ dump_hex(">> %s\n", xhdr, sizeof(*xhdr) + size);
+ xwrite(tls->fd, xhdr, sizeof(*xhdr) + size);
+ dbg("wrote %u bytes\n", (int)sizeof(*xhdr) + size);
+ /* Handshake hash does not include record headers */
+ sha256_hash_dbg(">> sha256:%s", &tls->handshake_sha256_ctx, buf, size);
+ return;
+ }
+ xwrite_encrypted(tls, size, RECORD_TYPE_HANDSHAKE);
+}
+
static int xread_tls_block(tls_state_t *tls)
{
struct record_hdr *xhdr;
@@ -668,7 +703,7 @@ static int xread_tls_block(tls_state_t *tls)
sz = target - sizeof(*xhdr);
/* Needs to be decrypted? */
- if (tls->min_encrypted_len_on_read) {
+ if (tls->min_encrypted_len_on_read > SHA256_OUTSIZE) {
psCipherContext_t ctx;
uint8_t *p = tls->inbuf + sizeof(*xhdr);
int padding_len;
@@ -698,6 +733,10 @@ static int xread_tls_block(tls_state_t *tls)
/* Skip IV */
memmove(tls->inbuf + 5, tls->inbuf + 5 + AES_BLOCKSIZE, sz);
}
+ } else {
+ /* if nonzero, then it's TLS_RSA_WITH_NULL_SHA256: drop MAC */
+ /* else: no encryption yet on input, subtract zero = NOP */
+ sz -= tls->min_encrypted_len_on_read;
}
/* RFC 5246 is not saying it explicitly, but sha256 hash
@@ -943,39 +982,24 @@ static int xread_tls_handshake_block(tls_state_t *tls, int min_len)
return len;
}
-static void fill_handshake_record_hdr(struct record_hdr *xhdr, unsigned len)
+static ALWAYS_INLINE void fill_handshake_record_hdr(void *buf, unsigned type, unsigned len)
{
struct handshake_hdr {
- struct record_hdr xhdr;
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
- } *h = (void*)xhdr;
-
- h->xhdr.type = RECORD_TYPE_HANDSHAKE;
- h->xhdr.proto_maj = TLS_MAJ;
- h->xhdr.proto_min = TLS_MIN;
- len -= 5;
- h->xhdr.len16_hi = len >> 8;
- // can be optimized to do one store instead of four:
- // uint32_t v = htonl(0x100*(RECORD_TYPE_HANDSHAKE + 0x100*(TLS_MAJ + 0x100*(TLS_MIN))))
- // | ((len >> 8) << 24); // little-endian specific, don't use in this form
- // *(uint32_t *)xhdr = v;
-
- h->xhdr.len16_lo = len & 0xff;
+ } *h = buf;
len -= 4;
+ h->type = type;
h->len24_hi = len >> 16;
h->len24_mid = len >> 8;
h->len24_lo = len & 0xff;
-
- memset(h + 1, 0, len);
}
//TODO: implement RFC 5746 (Renegotiation Indication Extension) - some servers will refuse to work with us otherwise
static void send_client_hello(tls_state_t *tls)
{
struct client_hello {
- struct record_hdr xhdr;
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
uint8_t proto_maj, proto_min;
@@ -987,25 +1011,25 @@ static void send_client_hello(tls_state_t *tls)
uint8_t comprtypes_len;
uint8_t comprtypes[1]; /* actually variable */
};
- struct client_hello record;
-
- fill_handshake_record_hdr(&record.xhdr, sizeof(record));
- record.type = HANDSHAKE_CLIENT_HELLO;
- record.proto_maj = TLS_MAJ; /* the "requested" version of the protocol, */
- record.proto_min = TLS_MIN; /* can be higher than one in record headers */
- tls_get_random(record.rand32, sizeof(record.rand32));
- /* record.session_id_len = 0; - already is */
- /* record.cipherid_len16_hi = 0; */
- record.cipherid_len16_lo = 2 * 1;
- record.cipherid[0] = CIPHER_ID >> 8;
- record.cipherid[1] = CIPHER_ID & 0xff;
- record.comprtypes_len = 1;
- /* record.comprtypes[0] = 0; */
+ struct client_hello *record = tls_get_outbuf(tls, sizeof(*record));
+
+ fill_handshake_record_hdr(record, HANDSHAKE_CLIENT_HELLO, sizeof(*record));
+ record->proto_maj = TLS_MAJ; /* the "requested" version of the protocol, */
+ record->proto_min = TLS_MIN; /* can be higher than one in record headers */
+ tls_get_random(record->rand32, sizeof(record->rand32));
+memset(record->rand32, 0x11, sizeof(record->rand32));
+ memcpy(tls->client_and_server_rand32, record->rand32, sizeof(record->rand32));
+ record->session_id_len = 0;
+ record->cipherid_len16_hi = 0;
+ record->cipherid_len16_lo = 2 * 1;
+ record->cipherid[0] = CIPHER_ID >> 8;
+ record->cipherid[1] = CIPHER_ID & 0xff;
+ record->comprtypes_len = 1;
+ record->comprtypes[0] = 0;
//dbg (make it repeatable): memset(record.rand32, 0x11, sizeof(record.rand32));
dbg(">> CLIENT_HELLO\n");
- xwrite_and_hash(tls, &record, sizeof(record));
- memcpy(tls->client_and_server_rand32, record.rand32, sizeof(record.rand32));
+ xwrite_and_update_handshake_hash(tls, sizeof(*record));
}
static void get_server_hello(tls_state_t *tls)
@@ -1099,21 +1123,19 @@ static void get_server_cert(tls_state_t *tls)
static void send_client_key_exchange(tls_state_t *tls)
{
struct client_key_exchange {
- struct record_hdr xhdr;
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
/* keylen16 exists for RSA (in TLS, not in SSL), but not for some other key types */
uint8_t keylen16_hi, keylen16_lo;
uint8_t key[4 * 1024]; // size??
};
- struct client_key_exchange record;
+//FIXME: better size estimate
+ struct client_key_exchange *record = tls_get_outbuf(tls, sizeof(*record));
uint8_t rsa_premaster[SSL_HS_RSA_PREMASTER_SIZE];
int len;
- fill_handshake_record_hdr(&record.xhdr, sizeof(record) - sizeof(record.key));
- record.type = HANDSHAKE_CLIENT_KEY_EXCHANGE;
-
tls_get_random(rsa_premaster, sizeof(rsa_premaster));
+memset(rsa_premaster, 0x44, sizeof(rsa_premaster));
// RFC 5246
// "Note: The version number in the PreMasterSecret is the version
// offered by the client in the ClientHello.client_version, not the
@@ -1123,22 +1145,20 @@ static void send_client_key_exchange(tls_state_t *tls)
len = psRsaEncryptPub(/*pool:*/ NULL,
/* psRsaKey_t* */ &tls->server_rsa_pub_key,
rsa_premaster, /*inlen:*/ sizeof(rsa_premaster),
- record.key, sizeof(record.key),
+ record->key, sizeof(record->key),
data_param_ignored
);
- /* length fields need fixing */
- record.keylen16_hi = len >> 8;
- record.keylen16_lo = len & 0xff;
+ record->keylen16_hi = len >> 8;
+ record->keylen16_lo = len & 0xff;
len += 2;
- /* record.len24_hi = 0; - already is */
- record.len24_mid = len >> 8;
- record.len24_lo = len & 0xff;
+ record->type = HANDSHAKE_CLIENT_KEY_EXCHANGE;
+ record->len24_hi = 0;
+ record->len24_mid = len >> 8;
+ record->len24_lo = len & 0xff;
len += 4;
- record.xhdr.len16_hi = len >> 8;
- record.xhdr.len16_lo = len & 0xff;
dbg(">> CLIENT_KEY_EXCHANGE\n");
- xwrite_and_hash(tls, &record, sizeof(record.xhdr) + len);
+ xwrite_and_update_handshake_hash(tls, len);
// RFC 5246
// For all key exchange methods, the same algorithm is used to convert
@@ -1224,7 +1244,6 @@ static const uint8_t rec_CHANGE_CIPHER_SPEC[] = {
static void send_change_cipher_spec(tls_state_t *tls)
{
- /* Not "xwrite_and_hash": this is not a handshake message */
dbg(">> CHANGE_CIPHER_SPEC\n");
xwrite(tls->fd, rec_CHANGE_CIPHER_SPEC, sizeof(rec_CHANGE_CIPHER_SPEC));
}
@@ -1269,19 +1288,17 @@ static void send_change_cipher_spec(tls_state_t *tls)
static void send_client_finished(tls_state_t *tls)
{
struct finished {
- struct record_hdr xhdr;
uint8_t type;
uint8_t len24_hi, len24_mid, len24_lo;
uint8_t prf_result[12];
};
- struct finished record;
+ struct finished *record = tls_get_outbuf(tls, sizeof(*record));
uint8_t handshake_hash[SHA256_OUTSIZE];
- fill_handshake_record_hdr(&record.xhdr, sizeof(record));
- record.type = HANDSHAKE_FINISHED;
+ fill_handshake_record_hdr(record, HANDSHAKE_FINISHED, sizeof(*record));
sha256_peek(&tls->handshake_sha256_ctx, handshake_hash);
- prf_hmac_sha256(record.prf_result, sizeof(record.prf_result),
+ prf_hmac_sha256(record->prf_result, sizeof(record->prf_result),
tls->master_secret, sizeof(tls->master_secret),
"client finished",
handshake_hash, sizeof(handshake_hash)
@@ -1289,13 +1306,10 @@ static void send_client_finished(tls_state_t *tls)
dump_hex("from secret: %s\n", tls->master_secret, sizeof(tls->master_secret));
dump_hex("from labelSeed: %s", "client finished", sizeof("client finished")-1);
dump_hex("%s\n", handshake_hash, sizeof(handshake_hash));
- dump_hex("=> digest: %s\n", record.prf_result, sizeof(record.prf_result));
-
-//(1) TODO: well, this should be encrypted on send, really.
-//(2) do we really need to also hash it?
+ dump_hex("=> digest: %s\n", record->prf_result, sizeof(record->prf_result));
dbg(">> FINISHED\n");
- xwrite_and_hash(tls, &record, sizeof(record));
+ xwrite_encrypted(tls, sizeof(*record), RECORD_TYPE_HANDSHAKE);
}
static void tls_handshake(tls_state_t *tls)
@@ -1376,8 +1390,11 @@ static void tls_handshake(tls_state_t *tls)
if (len != 1 || memcmp(tls->inbuf, rec_CHANGE_CIPHER_SPEC, 6) != 0)
tls_error_die(tls);
dbg("<< CHANGE_CIPHER_SPEC\n");
- /* all incoming packets now should be encrypted and have IV + MAC + padding */
- tls->min_encrypted_len_on_read = AES_BLOCKSIZE + SHA256_OUTSIZE + AES_BLOCKSIZE;
+ if (CIPHER_ID == TLS_RSA_WITH_NULL_SHA256)
+ tls->min_encrypted_len_on_read = SHA256_OUTSIZE;
+ else
+ /* all incoming packets now should be encrypted and have IV + MAC + padding */
+ tls->min_encrypted_len_on_read = AES_BLOCKSIZE + SHA256_OUTSIZE + AES_BLOCKSIZE;
/* Get (encrypted) FINISHED from the server */
len = xread_tls_block(tls);
@@ -1387,6 +1404,12 @@ static void tls_handshake(tls_state_t *tls)
/* application data can be sent/received */
}
+static void tls_xwrite(tls_state_t *tls, int len)
+{
+ dbg(">> DATA\n");
+ xwrite_encrypted(tls, len, RECORD_TYPE_APPLICATION_DATA);
+}
+
// To run a test server using openssl:
// openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost'
// openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1
@@ -1400,8 +1423,8 @@ int tls_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int tls_main(int argc UNUSED_PARAM, char **argv)
{
tls_state_t *tls;
- len_and_sockaddr *lsa;
- int fd;
+ fd_set readfds, testfds;
+ int cfd;
// INIT_G();
// getopt32(argv, "myopts")
@@ -1409,13 +1432,48 @@ int tls_main(int argc UNUSED_PARAM, char **argv)
if (!argv[1])
bb_show_usage();
- lsa = xhost2sockaddr(argv[1], 443);
- fd = xconnect_stream(lsa);
+ cfd = create_and_connect_stream_or_die(argv[1], 443);
tls = new_tls_state();
- tls->fd = fd;
+ tls->fd = cfd;
tls_handshake(tls);
+ /* Select loop copying stdin to cfd, and cfd to stdout */
+ FD_ZERO(&readfds);
+ FD_SET(cfd, &readfds);
+ FD_SET(STDIN_FILENO, &readfds);
+
+#define iobuf bb_common_bufsiz1
+ setup_common_bufsiz();
+ for (;;) {
+ int nread;
+
+ testfds = readfds;
+
+ if (select(cfd + 1, &testfds, NULL, NULL, NULL) < 0)
+ bb_perror_msg_and_die("select");
+
+ if (FD_ISSET(STDIN_FILENO, &testfds)) {
+ void *buf = tls_get_outbuf(tls, COMMON_BUFSIZE);
+ nread = safe_read(STDIN_FILENO, buf, COMMON_BUFSIZE);
+ if (nread < 1) {
+//&& errno != EAGAIN
+ /* Close outgoing half-connection so they get EOF,
+ * but leave incoming alone so we can see response */
+// shutdown(cfd, SHUT_WR);
+ FD_CLR(STDIN_FILENO, &readfds);
+ }
+ tls_xwrite(tls, nread);
+ }
+ if (FD_ISSET(cfd, &testfds)) {
+ nread = xread_tls_block(tls);
+ if (nread < 1)
+//if eof, just close stdout, but not exit!
+ return EXIT_SUCCESS;
+ xwrite(STDOUT_FILENO, tls->inbuf + 5, nread);
+ }
+ }
+
return EXIT_SUCCESS;
}
/* Unencryped SHA256 example:
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