On 3/20/2018 7:54 PM, Dave Watson wrote:
Add rx path for tls software implementation.
recvmsg, splice_read, and poll implemented.
An additional sockopt TLS_RX is added, with the same interface as
TLS_TX. Either TLX_RX or TLX_TX may be provided separately, or
together (with two different setsockopt calls with appropriate keys).
Control messages are passed via CMSG in a similar way to transmit.
If no cmsg buffer is passed, then only application data records
will be passed to userspace, and EIO is returned for other types of
alerts.
EBADMSG is passed for decryption errors, and EMSGSIZE is passed for
framing errors (either framing too big *or* too small with crypto
overhead). EINVAL is returned for TLS versions that do not match the
original setsockopt call. All are unrecoverable.
strparser is used to parse TLS framing. Decryption is done directly
in to userspace buffers if they are large enough to support it, otherwise
sk_cow_data is called (similar to ipsec), and buffers are decrypted in
place and copied. splice_read always decrypts in place, since no
buffers are provided to decrypt in to.
sk_poll is overridden, and only returns POLLIN if a full TLS message is
received. Otherwise we wait for strparser to finish reading a full frame.
Actual decryption is only done during recvmsg or splice_read calls.
Signed-off-by: Dave Watson <davejwatson@xxxxxx>
---
...
+
+static int tls_read_size(struct strparser *strp, struct sk_buff *skb)
+{
+ struct tls_context *tls_ctx = tls_get_ctx(strp->sk);
+ struct tls_sw_context *ctx = tls_sw_ctx(tls_ctx);
+ char header[tls_ctx->rx.prepend_size];
+ struct strp_msg *rxm = strp_msg(skb);
+ size_t cipher_overhead;
+ size_t data_len = 0;
+ int ret;
+
+ /* Verify that we have a full TLS header, or wait for more data */
+ if (rxm->offset + tls_ctx->rx.prepend_size > skb->len)
+ return 0;
+
+ /* Linearize header to local buffer */
+ ret = skb_copy_bits(skb, rxm->offset, header, tls_ctx->rx.prepend_size);
+
+ if (ret < 0)
+ goto read_failure;
+
+ ctx->control = header[0];
+
+ data_len = ((header[4] & 0xFF) | (header[3] << 8));
+
+ cipher_overhead = tls_ctx->rx.tag_size + tls_ctx->rx.iv_size;
+
+ if (data_len > TLS_MAX_PAYLOAD_SIZE + cipher_overhead) {
+ ret = -EMSGSIZE;
+ goto read_failure;
+ }
+ if (data_len < cipher_overhead) {
+ ret = -EMSGSIZE;
I think this should be considered EBADMSG, because this error is cipher
dependent. At least, that's what happens within OpenSSL. Also, EMSGSIZE
is usually used only for too long messages.
+ goto read_failure;
+ }
+
+ if (header[1] != TLS_VERSION_MINOR(tls_ctx->crypto_recv.version) ||
+ header[2] != TLS_VERSION_MAJOR(tls_ctx->crypto_recv.version)) {
+ ret = -EINVAL;
+ goto read_failure;
+ }
+
+ return data_len + TLS_HEADER_SIZE;
+
+read_failure:
+ tls_err_abort(strp->sk, ret);
+
+ return ret;
+}
+
...
