net/tls: Fix flipped sign in tls_err_abort() calls

sk->sk_err appears to expect a positive value, a convention that ktls
doesn't always follow and that leads to memory corruption in other code.
For instance,

[kworker]
tls_encrypt_done(..., err=<negative error from crypto request>)
tls_err_abort(.., err)
sk->sk_err = err;

[task]
splice_from_pipe_feed
...
tls_sw_do_sendpage
if (sk->sk_err) {
ret = -sk->sk_err; // ret is positive

splice_from_pipe_feed (continued)
ret = actor(...) // ret is still positive and interpreted as bytes
// written, resulting in underflow of buf->len and
// sd->len, leading to huge buf->offset and bogus
// addresses computed in later calls to actor()

Fix all tls_err_abort() callers to pass a negative error code
consistently and centralize the error-prone sign flip there, throwing in
a warning to catch future misuse and uninlining the function so it
really does only warn once.

Cc: [e-mail]
Fixes: c46234ebb4d1e ("tls: RX path for ktls")
Reported-by: [e-mail]
Signed-off-by: Daniel Jordan <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/tls.h

···
 		int __user *optlen);
 int tls_sk_attach(struct sock *sk, int optname, char __user *optval,
 		  unsigned int optlen);
+void tls_err_abort(struct sock *sk, int err);
 
 int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx);
 void tls_sw_strparser_arm(struct sock *sk, struct tls_context *ctx);
···
 #endif
 }
 
-static inline void tls_err_abort(struct sock *sk, int err)
-{
-	sk->sk_err = err;
-	sk_error_report(sk);
-}
-
 static inline bool tls_bigint_increment(unsigned char *seq, int len)
 {
 	int i;
···
 					 struct cipher_context *ctx)
 {
 	if (tls_bigint_increment(ctx->rec_seq, prot->rec_seq_size))
-		tls_err_abort(sk, EBADMSG);
+		tls_err_abort(sk, -EBADMSG);
 
 	if (prot->version != TLS_1_3_VERSION &&
 	    prot->cipher_type != TLS_CIPHER_CHACHA20_POLY1305)

net/tls/tls_sw.c

···
  * SOFTWARE.
  */
 
+#include <linux/bug.h>
 #include <linux/sched/signal.h>
 #include <linux/module.h>
 #include <linux/splice.h>
···
 
 #include <net/strparser.h>
 #include <net/tls.h>
+
+noinline void tls_err_abort(struct sock *sk, int err)
+{
+	WARN_ON_ONCE(err >= 0);
+	/* sk->sk_err should contain a positive error code. */
+	sk->sk_err = -err;
+	sk_error_report(sk);
+}
 
 static int __skb_nsg(struct sk_buff *skb, int offset, int len,
                      unsigned int recursion_level)
···
 
 tx_err:
 	if (rc < 0 && rc != -EAGAIN)
-		tls_err_abort(sk, EBADMSG);
+		tls_err_abort(sk, -EBADMSG);
 
 	return rc;
 }
···
 			       msg_pl->sg.size + prot->tail_size, i);
 	if (rc < 0) {
 		if (rc != -EINPROGRESS) {
-			tls_err_abort(sk, EBADMSG);
+			tls_err_abort(sk, -EBADMSG);
 			if (split) {
 				tls_ctx->pending_open_record_frags = true;
 				tls_merge_open_record(sk, rec, tmp, orig_end);
···
 		err = decrypt_skb_update(sk, skb, &msg->msg_iter,
 					 &chunk, &zc, async_capable);
 		if (err < 0 && err != -EINPROGRESS) {
-			tls_err_abort(sk, EBADMSG);
+			tls_err_abort(sk, -EBADMSG);
 			goto recv_end;
 		}
 
···
 		}
 
 		if (err < 0) {
-			tls_err_abort(sk, EBADMSG);
+			tls_err_abort(sk, -EBADMSG);
 			goto splice_read_end;
 		}
 		ctx->decrypted = 1;