1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * if_alg: User-space algorithm interface 4 * 5 * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au> 6 */ 7 8 #ifndef _CRYPTO_IF_ALG_H 9 #define _CRYPTO_IF_ALG_H 10 11 #include <linux/bits.h> 12 #include <linux/compiler.h> 13 #include <linux/completion.h> 14 #include <linux/if_alg.h> 15 #include <linux/scatterlist.h> 16 #include <linux/types.h> 17 #include <linux/atomic.h> 18 #include <net/sock.h> 19 20 #include <crypto/aead.h> 21 #include <crypto/skcipher.h> 22 23 #define ALG_MAX_PAGES 16 24 25 struct alg_sock { 26 /* struct sock must be the first member of struct alg_sock */ 27 struct sock sk; 28 29 struct sock *parent; 30 31 atomic_t refcnt; 32 atomic_t nokey_refcnt; 33 34 const struct af_alg_type *type; 35 void *private; 36 }; 37 38 struct af_alg_control { 39 struct af_alg_iv *iv; 40 int op; 41 unsigned int aead_assoclen; 42 }; 43 44 struct af_alg_type { 45 void *(*bind)(const char *name); 46 void (*release)(void *private); 47 int (*setkey)(void *private, const u8 *key, unsigned int keylen); 48 int (*setentropy)(void *private, sockptr_t entropy, unsigned int len); 49 int (*accept)(void *private, struct sock *sk); 50 int (*accept_nokey)(void *private, struct sock *sk); 51 int (*setauthsize)(void *private, unsigned int authsize); 52 53 struct proto_ops *ops; 54 struct proto_ops *ops_nokey; 55 struct module *owner; 56 char name[14]; 57 }; 58 59 struct af_alg_sgl { 60 struct sg_table sgt; 61 struct scatterlist sgl[ALG_MAX_PAGES + 1]; 62 bool need_unpin; 63 }; 64 65 /* TX SGL entry */ 66 struct af_alg_tsgl { 67 struct list_head list; 68 unsigned int cur; /* Last processed SG entry */ 69 struct scatterlist sg[]; /* Array of SGs forming the SGL */ 70 }; 71 72 #define MAX_SGL_ENTS ((4096 - sizeof(struct af_alg_tsgl)) / \ 73 sizeof(struct scatterlist) - 1) 74 75 /* RX SGL entry */ 76 struct af_alg_rsgl { 77 struct af_alg_sgl sgl; 78 struct list_head list; 79 size_t sg_num_bytes; /* Bytes of data in that SGL */ 80 }; 81 82 /** 83 * struct af_alg_async_req - definition of crypto request 84 * @sk: Socket the request is associated with 85 * @first_rsgl: First RX SG 86 * @last_rsgl: Pointer to last RX SG 87 * @rsgl_list: Track RX SGs 88 * @tsgl: Private, per request TX SGL of buffers to process 89 * @tsgl_entries: Number of entries in priv. TX SGL 90 * @outlen: Number of output bytes generated by crypto op 91 * @areqlen: Length of this data structure 92 * @cra_u: Cipher request 93 */ 94 struct af_alg_async_req { 95 struct sock *sk; 96 97 struct af_alg_rsgl first_rsgl; 98 struct af_alg_rsgl *last_rsgl; 99 struct list_head rsgl_list; 100 101 struct scatterlist *tsgl; 102 unsigned int tsgl_entries; 103 104 unsigned int outlen; 105 unsigned int areqlen; 106 107 union { 108 struct aead_request aead_req; 109 struct skcipher_request skcipher_req; 110 } cra_u; 111 112 /* req ctx trails this struct */ 113 }; 114 115 /** 116 * struct af_alg_ctx - definition of the crypto context 117 * 118 * The crypto context tracks the input data during the lifetime of an AF_ALG 119 * socket. 120 * 121 * @tsgl_list: Link to TX SGL 122 * @iv: IV for cipher operation 123 * @state: Existing state for continuing operation 124 * @aead_assoclen: Length of AAD for AEAD cipher operations 125 * @wait: For waiting for completion of async crypto ops 126 * @used: TX bytes sent to kernel. This variable is used to 127 * ensure that user space cannot cause the kernel 128 * to allocate too much memory in sendmsg operation. 129 * @rcvused: Total RX bytes to be filled by kernel. This variable 130 * is used to ensure user space cannot cause the kernel 131 * to allocate too much memory in a recvmsg operation. 132 * @more: More data to be expected from user space? 133 * @merge: Shall new data from user space be merged into existing 134 * SG? 135 * @enc: Cryptographic operation to be performed when 136 * recvmsg is invoked. 137 * @write: True if we are in the middle of a write. 138 * @init: True if metadata has been sent. 139 * @len: Length of memory allocated for this data structure. 140 * @inflight: Non-zero when requests are in flight, for debugging only. 141 */ 142 struct af_alg_ctx { 143 struct list_head tsgl_list; 144 145 void *iv; 146 void *state; 147 size_t aead_assoclen; 148 149 struct crypto_wait wait; 150 151 size_t used; 152 atomic_t rcvused; 153 154 bool more:1, 155 merge:1, 156 enc:1, 157 write:1, 158 init:1; 159 160 unsigned int len; 161 162 unsigned int inflight; 163 }; 164 165 /* Flags for af_alg_allowlist_entry::flags: */ 166 #define AF_ALG_UNPRIVILEGED BIT(0) /* Unprivileged use is allowed */ 167 168 struct af_alg_allowlist_entry { 169 const char *name; 170 u32 flags; 171 }; 172 173 int af_alg_register_type(const struct af_alg_type *type); 174 int af_alg_unregister_type(const struct af_alg_type *type); 175 176 int af_alg_check_restriction(const char *name, 177 const struct af_alg_allowlist_entry allowlist[]); 178 179 int af_alg_release(struct socket *sock); 180 void af_alg_release_parent(struct sock *sk); 181 int af_alg_accept(struct sock *sk, struct socket *newsock, 182 struct proto_accept_arg *arg); 183 184 void af_alg_free_sg(struct af_alg_sgl *sgl); 185 186 static inline struct alg_sock *alg_sk(struct sock *sk) 187 { 188 return (struct alg_sock *)sk; 189 } 190 191 /** 192 * af_alg_sndbuf - Size of available buffer for sending data from user space to kernel. 193 * 194 * @sk: socket of connection to user space 195 * 196 * Returns: number of bytes still available 197 */ 198 static inline int af_alg_sndbuf(struct sock *sk) 199 { 200 struct alg_sock *ask = alg_sk(sk); 201 struct af_alg_ctx *ctx = ask->private; 202 203 return max_t(int, max_t(int, sk->sk_sndbuf & PAGE_MASK, PAGE_SIZE) - 204 ctx->used, 0); 205 } 206 207 /** 208 * af_alg_writable - Can the send buffer still be written to? 209 * 210 * @sk: socket of connection to user space 211 * 212 * Returns: true => writable, false => not writable 213 */ 214 static inline bool af_alg_writable(struct sock *sk) 215 { 216 return PAGE_SIZE <= af_alg_sndbuf(sk); 217 } 218 219 /** 220 * af_alg_rcvbuf - Size of available buffer used by kernel for the RX user space operation. 221 * 222 * @sk: socket of connection to user space 223 * 224 * Returns: number of bytes still available 225 */ 226 static inline int af_alg_rcvbuf(struct sock *sk) 227 { 228 struct alg_sock *ask = alg_sk(sk); 229 struct af_alg_ctx *ctx = ask->private; 230 231 return max_t(int, max_t(int, sk->sk_rcvbuf & PAGE_MASK, PAGE_SIZE) - 232 atomic_read(&ctx->rcvused), 0); 233 } 234 235 /** 236 * af_alg_readable - Can the RX buffer still be read from? 237 * 238 * @sk: socket of connection to user space 239 * 240 * Returns: true => readable, false => not readable 241 */ 242 static inline bool af_alg_readable(struct sock *sk) 243 { 244 return PAGE_SIZE <= af_alg_rcvbuf(sk); 245 } 246 247 unsigned int af_alg_count_tsgl(struct sock *sk, size_t bytes); 248 void af_alg_pull_tsgl(struct sock *sk, size_t used, struct scatterlist *dst); 249 void af_alg_wmem_wakeup(struct sock *sk); 250 int af_alg_wait_for_data(struct sock *sk, unsigned flags, unsigned min); 251 int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size, 252 unsigned int ivsize); 253 void af_alg_free_resources(struct af_alg_async_req *areq); 254 __poll_t af_alg_poll(struct file *file, struct socket *sock, 255 poll_table *wait); 256 struct af_alg_async_req *af_alg_alloc_areq(struct sock *sk, 257 unsigned int areqlen); 258 int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags, 259 struct af_alg_async_req *areq, size_t maxsize, 260 size_t *outlen); 261 262 /* 263 * Mask used to disable unsupported algorithm implementations. 264 * 265 * This is the same as FSCRYPT_CRYPTOAPI_MASK in fs/crypto/fscrypt_private.h. 266 * In additions to the motivations there, this API is exposed to userspace 267 * that might not be fully trusted. 268 */ 269 #define AF_ALG_CRYPTOAPI_MASK \ 270 (CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY | \ 271 CRYPTO_ALG_KERN_DRIVER_ONLY) 272 273 274 #endif /* _CRYPTO_IF_ALG_H */ 275