1 /*
2  * if_alg: User-space algorithm interface
3  *
4  * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the Free
8  * Software Foundation; either version 2 of the License, or (at your option)
9  * any later version.
10  *
11  */
12 
13 #ifndef _CRYPTO_IF_ALG_H
14 #define _CRYPTO_IF_ALG_H
15 
16 #include <linux/compiler.h>
17 #include <linux/completion.h>
18 #include <linux/if_alg.h>
19 #include <linux/scatterlist.h>
20 #include <linux/types.h>
21 #include <linux/atomic.h>
22 #include <net/sock.h>
23 
24 #include <crypto/aead.h>
25 #include <crypto/skcipher.h>
26 
27 #define ALG_MAX_PAGES			16
28 
29 struct crypto_async_request;
30 
31 struct alg_sock {
32 	/* struct sock must be the first member of struct alg_sock */
33 	struct sock sk;
34 
35 	struct sock *parent;
36 
37 	atomic_t refcnt;
38 	atomic_t nokey_refcnt;
39 
40 	const struct af_alg_type *type;
41 	void *private;
42 };
43 
44 struct af_alg_control {
45 	struct af_alg_iv *iv;
46 	int op;
47 	unsigned int aead_assoclen;
48 };
49 
50 struct af_alg_type {
51 	void *(*bind)(const char *name, u32 type, u32 mask);
52 	void (*release)(void *private);
53 	int (*setkey)(void *private, const u8 *key, unsigned int keylen);
54 	int (*accept)(void *private, struct sock *sk);
55 	int (*accept_nokey)(void *private, struct sock *sk);
56 	int (*setauthsize)(void *private, unsigned int authsize);
57 
58 	struct proto_ops *ops;
59 	struct proto_ops *ops_nokey;
60 	struct module *owner;
61 	char name[14];
62 };
63 
64 struct af_alg_sgl {
65 	struct scatterlist sg[ALG_MAX_PAGES + 1];
66 	struct page *pages[ALG_MAX_PAGES];
67 	unsigned int npages;
68 };
69 
70 /* TX SGL entry */
71 struct af_alg_tsgl {
72 	struct list_head list;
73 	unsigned int cur;		/* Last processed SG entry */
74 	struct scatterlist sg[0];	/* Array of SGs forming the SGL */
75 };
76 
77 #define MAX_SGL_ENTS ((4096 - sizeof(struct af_alg_tsgl)) / \
78 		      sizeof(struct scatterlist) - 1)
79 
80 /* RX SGL entry */
81 struct af_alg_rsgl {
82 	struct af_alg_sgl sgl;
83 	struct list_head list;
84 	size_t sg_num_bytes;		/* Bytes of data in that SGL */
85 };
86 
87 /**
88  * struct af_alg_async_req - definition of crypto request
89  * @iocb:		IOCB for AIO operations
90  * @sk:			Socket the request is associated with
91  * @first_rsgl:		First RX SG
92  * @last_rsgl:		Pointer to last RX SG
93  * @rsgl_list:		Track RX SGs
94  * @tsgl:		Private, per request TX SGL of buffers to process
95  * @tsgl_entries:	Number of entries in priv. TX SGL
96  * @outlen:		Number of output bytes generated by crypto op
97  * @areqlen:		Length of this data structure
98  * @cra_u:		Cipher request
99  */
100 struct af_alg_async_req {
101 	struct kiocb *iocb;
102 	struct sock *sk;
103 
104 	struct af_alg_rsgl first_rsgl;
105 	struct af_alg_rsgl *last_rsgl;
106 	struct list_head rsgl_list;
107 
108 	struct scatterlist *tsgl;
109 	unsigned int tsgl_entries;
110 
111 	unsigned int outlen;
112 	unsigned int areqlen;
113 
114 	union {
115 		struct aead_request aead_req;
116 		struct skcipher_request skcipher_req;
117 	} cra_u;
118 
119 	/* req ctx trails this struct */
120 };
121 
122 /**
123  * struct af_alg_ctx - definition of the crypto context
124  *
125  * The crypto context tracks the input data during the lifetime of an AF_ALG
126  * socket.
127  *
128  * @tsgl_list:		Link to TX SGL
129  * @iv:			IV for cipher operation
130  * @aead_assoclen:	Length of AAD for AEAD cipher operations
131  * @completion:		Work queue for synchronous operation
132  * @used:		TX bytes sent to kernel. This variable is used to
133  *			ensure that user space cannot cause the kernel
134  *			to allocate too much memory in sendmsg operation.
135  * @rcvused:		Total RX bytes to be filled by kernel. This variable
136  *			is used to ensure user space cannot cause the kernel
137  *			to allocate too much memory in a recvmsg operation.
138  * @more:		More data to be expected from user space?
139  * @merge:		Shall new data from user space be merged into existing
140  *			SG?
141  * @enc:		Cryptographic operation to be performed when
142  *			recvmsg is invoked.
143  * @len:		Length of memory allocated for this data structure.
144  */
145 struct af_alg_ctx {
146 	struct list_head tsgl_list;
147 
148 	void *iv;
149 	size_t aead_assoclen;
150 
151 	struct crypto_wait wait;
152 
153 	size_t used;
154 	atomic_t rcvused;
155 
156 	bool more;
157 	bool merge;
158 	bool enc;
159 
160 	unsigned int len;
161 };
162 
163 int af_alg_register_type(const struct af_alg_type *type);
164 int af_alg_unregister_type(const struct af_alg_type *type);
165 
166 int af_alg_release(struct socket *sock);
167 void af_alg_release_parent(struct sock *sk);
168 int af_alg_accept(struct sock *sk, struct socket *newsock, bool kern);
169 
170 int af_alg_make_sg(struct af_alg_sgl *sgl, struct iov_iter *iter, int len);
171 void af_alg_free_sg(struct af_alg_sgl *sgl);
172 void af_alg_link_sg(struct af_alg_sgl *sgl_prev, struct af_alg_sgl *sgl_new);
173 
174 int af_alg_cmsg_send(struct msghdr *msg, struct af_alg_control *con);
175 
alg_sk(struct sock * sk)176 static inline struct alg_sock *alg_sk(struct sock *sk)
177 {
178 	return (struct alg_sock *)sk;
179 }
180 
181 /**
182  * Size of available buffer for sending data from user space to kernel.
183  *
184  * @sk socket of connection to user space
185  * @return number of bytes still available
186  */
af_alg_sndbuf(struct sock * sk)187 static inline int af_alg_sndbuf(struct sock *sk)
188 {
189 	struct alg_sock *ask = alg_sk(sk);
190 	struct af_alg_ctx *ctx = ask->private;
191 
192 	return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) -
193 			  ctx->used, 0);
194 }
195 
196 /**
197  * Can the send buffer still be written to?
198  *
199  * @sk socket of connection to user space
200  * @return true => writable, false => not writable
201  */
af_alg_writable(struct sock * sk)202 static inline bool af_alg_writable(struct sock *sk)
203 {
204 	return PAGE_SIZE <= af_alg_sndbuf(sk);
205 }
206 
207 /**
208  * Size of available buffer used by kernel for the RX user space operation.
209  *
210  * @sk socket of connection to user space
211  * @return number of bytes still available
212  */
af_alg_rcvbuf(struct sock * sk)213 static inline int af_alg_rcvbuf(struct sock *sk)
214 {
215 	struct alg_sock *ask = alg_sk(sk);
216 	struct af_alg_ctx *ctx = ask->private;
217 
218 	return max_t(int, max_t(int, sk->sk_rcvbuf & PAGE_MASK, PAGE_SIZE) -
219 		     atomic_read(&ctx->rcvused), 0);
220 }
221 
222 /**
223  * Can the RX buffer still be written to?
224  *
225  * @sk socket of connection to user space
226  * @return true => writable, false => not writable
227  */
af_alg_readable(struct sock * sk)228 static inline bool af_alg_readable(struct sock *sk)
229 {
230 	return PAGE_SIZE <= af_alg_rcvbuf(sk);
231 }
232 
233 int af_alg_alloc_tsgl(struct sock *sk);
234 unsigned int af_alg_count_tsgl(struct sock *sk, size_t bytes, size_t offset);
235 void af_alg_pull_tsgl(struct sock *sk, size_t used, struct scatterlist *dst,
236 		      size_t dst_offset);
237 void af_alg_free_areq_sgls(struct af_alg_async_req *areq);
238 int af_alg_wait_for_wmem(struct sock *sk, unsigned int flags);
239 void af_alg_wmem_wakeup(struct sock *sk);
240 int af_alg_wait_for_data(struct sock *sk, unsigned flags);
241 void af_alg_data_wakeup(struct sock *sk);
242 int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
243 		   unsigned int ivsize);
244 ssize_t af_alg_sendpage(struct socket *sock, struct page *page,
245 			int offset, size_t size, int flags);
246 void af_alg_free_resources(struct af_alg_async_req *areq);
247 void af_alg_async_cb(struct crypto_async_request *_req, int err);
248 __poll_t af_alg_poll(struct file *file, struct socket *sock,
249 			 poll_table *wait);
250 struct af_alg_async_req *af_alg_alloc_areq(struct sock *sk,
251 					   unsigned int areqlen);
252 int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,
253 		    struct af_alg_async_req *areq, size_t maxsize,
254 		    size_t *outlen);
255 
256 #endif	/* _CRYPTO_IF_ALG_H */
257