crypto: af_alg - consolidation of duplicate code

Consolidate following data structures:

skcipher_async_req, aead_async_req -> af_alg_async_req
skcipher_rsgl, aead_rsql -> af_alg_rsgl
skcipher_tsgl, aead_tsql -> af_alg_tsgl
skcipher_ctx, aead_ctx -> af_alg_ctx

Consolidate following functions:

skcipher_sndbuf, aead_sndbuf -> af_alg_sndbuf
skcipher_writable, aead_writable -> af_alg_writable
skcipher_rcvbuf, aead_rcvbuf -> af_alg_rcvbuf
skcipher_readable, aead_readable -> af_alg_readable
aead_alloc_tsgl, skcipher_alloc_tsgl -> af_alg_alloc_tsgl
aead_count_tsgl, skcipher_count_tsgl -> af_alg_count_tsgl
aead_pull_tsgl, skcipher_pull_tsgl -> af_alg_pull_tsgl
aead_free_areq_sgls, skcipher_free_areq_sgls -> af_alg_free_areq_sgls
aead_wait_for_wmem, skcipher_wait_for_wmem -> af_alg_wait_for_wmem
aead_wmem_wakeup, skcipher_wmem_wakeup -> af_alg_wmem_wakeup
aead_wait_for_data, skcipher_wait_for_data -> af_alg_wait_for_data
aead_data_wakeup, skcipher_data_wakeup -> af_alg_data_wakeup
aead_sendmsg, skcipher_sendmsg -> af_alg_sendmsg
aead_sendpage, skcipher_sendpage -> af_alg_sendpage
aead_async_cb, skcipher_async_cb -> af_alg_async_cb
aead_poll, skcipher_poll -> af_alg_poll

Split out the following common code from recvmsg:

af_alg_alloc_areq: allocation of the request data structure for the
cipher operation

af_alg_get_rsgl: creation of the RX SGL anchored in the request data
structure

The following changes to the implementation without affecting the
functionality have been applied to synchronize slightly different code
bases in algif_skcipher and algif_aead:

The wakeup in af_alg_wait_for_data is triggered when either more data
is received or the indicator that more data is to be expected is
released. The first is triggered by user space, the second is
triggered by the kernel upon finishing the processing of data
(i.e. the kernel is ready for more).

af_alg_sendmsg uses size_t in min_t calculation for obtaining len.
Return code determination is consistent with algif_skcipher. The
scope of the variable i is reduced to match algif_aead. The type of the
variable i is switched from int to unsigned int to match algif_aead.

af_alg_sendpage does not contain the superfluous err = 0 from
aead_sendpage.

af_alg_async_cb requires to store the number of output bytes in
areq->outlen before the AIO callback is triggered.

The POLLIN / POLLRDNORM is now set when either not more data is given or
the kernel is supplied with data. This is consistent to the wakeup from
sleep when the kernel waits for data.

The request data structure is extended by the field last_rsgl which
points to the last RX SGL list entry. This shall help recvmsg
implementation to chain the RX SGL to other SG(L)s if needed. It is
currently used by algif_aead which chains the tag SGL to the RX SGL
during decryption.
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/crypto/if_alg.h

@@ -20,6 +20,9 @@
 #include <linux/types.h>
 #include <net/sock.h>
 
+#include <crypto/aead.h>
+#include <crypto/skcipher.h>
+
 #define ALG_MAX_PAGES			16
 
 struct crypto_async_request;
@@ -68,6 +71,99 @@ struct af_alg_sgl {
 	unsigned int npages;
 };
 
+/* TX SGL entry */
+struct af_alg_tsgl {
+	struct list_head list;
+	unsigned int cur;		/* Last processed SG entry */
+	struct scatterlist sg[0];	/* Array of SGs forming the SGL */
+};
+
+#define MAX_SGL_ENTS ((4096 - sizeof(struct af_alg_tsgl)) / \
+		      sizeof(struct scatterlist) - 1)
+
+/* RX SGL entry */
+struct af_alg_rsgl {
+	struct af_alg_sgl sgl;
+	struct list_head list;
+	size_t sg_num_bytes;		/* Bytes of data in that SGL */
+};
+
+/**
+ * struct af_alg_async_req - definition of crypto request
+ * @iocb:		IOCB for AIO operations
+ * @sk:			Socket the request is associated with
+ * @first_rsgl:		First RX SG
+ * @last_rsgl:		Pointer to last RX SG
+ * @rsgl_list:		Track RX SGs
+ * @tsgl:		Private, per request TX SGL of buffers to process
+ * @tsgl_entries:	Number of entries in priv. TX SGL
+ * @outlen:		Number of output bytes generated by crypto op
+ * @areqlen:		Length of this data structure
+ * @cra_u:		Cipher request
+ */
+struct af_alg_async_req {
+	struct kiocb *iocb;
+	struct sock *sk;
+
+	struct af_alg_rsgl first_rsgl;
+	struct af_alg_rsgl *last_rsgl;
+	struct list_head rsgl_list;
+
+	struct scatterlist *tsgl;
+	unsigned int tsgl_entries;
+
+	unsigned int outlen;
+	unsigned int areqlen;
+
+	union {
+		struct aead_request aead_req;
+		struct skcipher_request skcipher_req;
+	} cra_u;
+
+	/* req ctx trails this struct */
+};
+
+/**
+ * struct af_alg_ctx - definition of the crypto context
+ *
+ * The crypto context tracks the input data during the lifetime of an AF_ALG
+ * socket.
+ *
+ * @tsgl_list:		Link to TX SGL
+ * @iv:			IV for cipher operation
+ * @aead_assoclen:	Length of AAD for AEAD cipher operations
+ * @completion:		Work queue for synchronous operation
+ * @used:		TX bytes sent to kernel. This variable is used to
+ *			ensure that user space cannot cause the kernel
+ *			to allocate too much memory in sendmsg operation.
+ * @rcvused:		Total RX bytes to be filled by kernel. This variable
+ *			is used to ensure user space cannot cause the kernel
+ *			to allocate too much memory in a recvmsg operation.
+ * @more:		More data to be expected from user space?
+ * @merge:		Shall new data from user space be merged into existing
+ *			SG?
+ * @enc:		Cryptographic operation to be performed when
+ *			recvmsg is invoked.
+ * @len:		Length of memory allocated for this data structure.
+ */
+struct af_alg_ctx {
+	struct list_head tsgl_list;
+
+	void *iv;
+	size_t aead_assoclen;
+
+	struct af_alg_completion completion;
+
+	size_t used;
+	size_t rcvused;
+
+	bool more;
+	bool merge;
+	bool enc;
+
+	unsigned int len;
+};
+
 int af_alg_register_type(const struct af_alg_type *type);
 int af_alg_unregister_type(const struct af_alg_type *type);
 
@@ -94,4 +190,78 @@ static inline void af_alg_init_completion(struct af_alg_completion *completion)
 	init_completion(&completion->completion);
 }
 
+/**
+ * Size of available buffer for sending data from user space to kernel.
+ *
+ * @sk socket of connection to user space
+ * @return number of bytes still available
+ */
+static inline int af_alg_sndbuf(struct sock *sk)
+{
+	struct alg_sock *ask = alg_sk(sk);
+	struct af_alg_ctx *ctx = ask->private;
+
+	return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) -
+			  ctx->used, 0);
+}
+
+/**
+ * Can the send buffer still be written to?
+ *
+ * @sk socket of connection to user space
+ * @return true => writable, false => not writable
+ */
+static inline bool af_alg_writable(struct sock *sk)
+{
+	return PAGE_SIZE <= af_alg_sndbuf(sk);
+}
+
+/**
+ * Size of available buffer used by kernel for the RX user space operation.
+ *
+ * @sk socket of connection to user space
+ * @return number of bytes still available
+ */
+static inline int af_alg_rcvbuf(struct sock *sk)
+{
+	struct alg_sock *ask = alg_sk(sk);
+	struct af_alg_ctx *ctx = ask->private;
+
+	return max_t(int, max_t(int, sk->sk_rcvbuf & PAGE_MASK, PAGE_SIZE) -
+			  ctx->rcvused, 0);
+}
+
+/**
+ * Can the RX buffer still be written to?
+ *
+ * @sk socket of connection to user space
+ * @return true => writable, false => not writable
+ */
+static inline bool af_alg_readable(struct sock *sk)
+{
+	return PAGE_SIZE <= af_alg_rcvbuf(sk);
+}
+
+int af_alg_alloc_tsgl(struct sock *sk);
+unsigned int af_alg_count_tsgl(struct sock *sk, size_t bytes, size_t offset);
+void af_alg_pull_tsgl(struct sock *sk, size_t used, struct scatterlist *dst,
+		      size_t dst_offset);
+void af_alg_free_areq_sgls(struct af_alg_async_req *areq);
+int af_alg_wait_for_wmem(struct sock *sk, unsigned int flags);
+void af_alg_wmem_wakeup(struct sock *sk);
+int af_alg_wait_for_data(struct sock *sk, unsigned flags);
+void af_alg_data_wakeup(struct sock *sk);
+int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
+		   unsigned int ivsize);
+ssize_t af_alg_sendpage(struct socket *sock, struct page *page,
+			int offset, size_t size, int flags);
+void af_alg_async_cb(struct crypto_async_request *_req, int err);
+unsigned int af_alg_poll(struct file *file, struct socket *sock,
+			 poll_table *wait);
+struct af_alg_async_req *af_alg_alloc_areq(struct sock *sk,
+					   unsigned int areqlen);
+int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,
+		    struct af_alg_async_req *areq, size_t maxsize,
+		    size_t *outlen);
+
 #endif	/* _CRYPTO_IF_ALG_H */