crypto: chacha20-generic - refactor to allow varying number of rounds

In preparation for adding XChaCha12 support, rename/refactor
chacha20-generic to support different numbers of rounds.  The
justification for needing XChaCha12 support is explained in more detail
in the patch "crypto: chacha - add XChaCha12 support".

The only difference between ChaCha{8,12,20} are the number of rounds
itself; all other parts of the algorithm are the same.  Therefore,
remove the "20" from all definitions, structures, functions, files, etc.
that will be shared by all ChaCha versions.

Also make ->setkey() store the round count in the chacha_ctx (previously
chacha20_ctx).  The generic code then passes the round count through to
chacha_block().  There will be a ->setkey() function for each explicitly
allowed round count; the encrypt/decrypt functions will be the same.  I
decided not to do it the opposite way (same ->setkey() function for all
round counts, with different encrypt/decrypt functions) because that
would have required more boilerplate code in architecture-specific
implementations of ChaCha and XChaCha.

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Martin Willi <martin@strongswan.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 25 insertions, 26 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 2eb70e76ed35..38c6d1af6d1c 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -265,7 +265,7 @@
 #include <linux/syscalls.h>
 #include <linux/completion.h>
 #include <linux/uuid.h>
-#include <crypto/chacha20.h>
+#include <crypto/chacha.h>
 
 #include <asm/processor.h>
 #include <linux/uaccess.h>
@@ -431,11 +431,10 @@ static int crng_init = 0;
 #define crng_ready() (likely(crng_init > 1))
 static int crng_init_cnt = 0;
 static unsigned long crng_global_init_time = 0;
-#define CRNG_INIT_CNT_THRESH (2*CHACHA20_KEY_SIZE)
-static void _extract_crng(struct crng_state *crng,
-                          __u8 out[CHACHA20_BLOCK_SIZE]);
+#define CRNG_INIT_CNT_THRESH (2*CHACHA_KEY_SIZE)
+static void _extract_crng(struct crng_state *crng, __u8 out[CHACHA_BLOCK_SIZE]);
 static void _crng_backtrack_protect(struct crng_state *crng,
-                                    __u8 tmp[CHACHA20_BLOCK_SIZE], int used);
+                                    __u8 tmp[CHACHA_BLOCK_SIZE], int used);
 static void process_random_ready_list(void);
 static void _get_random_bytes(void *buf, int nbytes);
 
@@ -863,7 +862,7 @@ static int crng_fast_load(const char *cp, size_t len)
         }
         p = (unsigned char *) &primary_crng.state[4];
         while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) {
-                p[crng_init_cnt % CHACHA20_KEY_SIZE] ^= *cp;
+                p[crng_init_cnt % CHACHA_KEY_SIZE] ^= *cp;
                 cp++; crng_init_cnt++; len--;
         }
         spin_unlock_irqrestore(&primary_crng.lock, flags);
@@ -895,7 +894,7 @@ static int crng_slow_load(const char *cp, size_t len)
         unsigned long           flags;
         static unsigned char    lfsr = 1;
         unsigned char           tmp;
-        unsigned                i, max = CHACHA20_KEY_SIZE;
+        unsigned                i, max = CHACHA_KEY_SIZE;
         const char *            src_buf = cp;
         char *                  dest_buf = (char *) &primary_crng.state[4];
 
@@ -913,8 +912,8 @@ static int crng_slow_load(const char *cp, size_t len)
                 lfsr >>= 1;
                 if (tmp & 1)
                         lfsr ^= 0xE1;
-                tmp = dest_buf[i % CHACHA20_KEY_SIZE];
-                dest_buf[i % CHACHA20_KEY_SIZE] ^= src_buf[i % len] ^ lfsr;
+                tmp = dest_buf[i % CHACHA_KEY_SIZE];
+                dest_buf[i % CHACHA_KEY_SIZE] ^= src_buf[i % len] ^ lfsr;
                 lfsr += (tmp << 3) | (tmp >> 5);
         }
         spin_unlock_irqrestore(&primary_crng.lock, flags);
@@ -926,7 +925,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
         unsigned long   flags;
         int             i, num;
         union {
-                __u8    block[CHACHA20_BLOCK_SIZE];
+                __u8    block[CHACHA_BLOCK_SIZE];
                 __u32   key[8];
         } buf;
 
@@ -937,7 +936,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
         } else {
                 _extract_crng(&primary_crng, buf.block);
                 _crng_backtrack_protect(&primary_crng, buf.block,
-                                        CHACHA20_KEY_SIZE);
+                                        CHACHA_KEY_SIZE);
         }
         spin_lock_irqsave(&crng->lock, flags);
         for (i = 0; i < 8; i++) {
@@ -973,7 +972,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
 }
 
 static void _extract_crng(struct crng_state *crng,
-                          __u8 out[CHACHA20_BLOCK_SIZE])
+                          __u8 out[CHACHA_BLOCK_SIZE])
 {
         unsigned long v, flags;
 
@@ -990,7 +989,7 @@ static void _extract_crng(struct crng_state *crng,
         spin_unlock_irqrestore(&crng->lock, flags);
 }
 
-static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE])
+static void extract_crng(__u8 out[CHACHA_BLOCK_SIZE])
 {
         struct crng_state *crng = NULL;
 
@@ -1008,14 +1007,14 @@ static void extract_crng(__u8 out[CHACHA20_BLOCK_SIZE])
  * enough) to mutate the CRNG key to provide backtracking protection.
  */
 static void _crng_backtrack_protect(struct crng_state *crng,
-                                    __u8 tmp[CHACHA20_BLOCK_SIZE], int used)
+                                    __u8 tmp[CHACHA_BLOCK_SIZE], int used)
 {
         unsigned long   flags;
         __u32           *s, *d;
         int             i;
 
         used = round_up(used, sizeof(__u32));
-        if (used + CHACHA20_KEY_SIZE > CHACHA20_BLOCK_SIZE) {
+        if (used + CHACHA_KEY_SIZE > CHACHA_BLOCK_SIZE) {
                 extract_crng(tmp);
                 used = 0;
         }
@@ -1027,7 +1026,7 @@ static void _crng_backtrack_protect(struct crng_state *crng,
         spin_unlock_irqrestore(&crng->lock, flags);
 }
 
-static void crng_backtrack_protect(__u8 tmp[CHACHA20_BLOCK_SIZE], int used)
+static void crng_backtrack_protect(__u8 tmp[CHACHA_BLOCK_SIZE], int used)
 {
         struct crng_state *crng = NULL;
 
@@ -1042,8 +1041,8 @@ static void crng_backtrack_protect(__u8 tmp[CHACHA20_BLOCK_SIZE], int used)
 
 static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
 {
-        ssize_t ret = 0, i = CHACHA20_BLOCK_SIZE;
-        __u8 tmp[CHACHA20_BLOCK_SIZE] __aligned(4);
+        ssize_t ret = 0, i = CHACHA_BLOCK_SIZE;
+        __u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4);
         int large_request = (nbytes > 256);
 
         while (nbytes) {
@@ -1057,7 +1056,7 @@ static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
                 }
 
                 extract_crng(tmp);
-                i = min_t(int, nbytes, CHACHA20_BLOCK_SIZE);
+                i = min_t(int, nbytes, CHACHA_BLOCK_SIZE);
                 if (copy_to_user(buf, tmp, i)) {
                         ret = -EFAULT;
                         break;
@@ -1622,14 +1621,14 @@ static void _warn_unseeded_randomness(const char *func_name, void *caller,
  */
 static void _get_random_bytes(void *buf, int nbytes)
 {
-        __u8 tmp[CHACHA20_BLOCK_SIZE] __aligned(4);
+        __u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4);
 
         trace_get_random_bytes(nbytes, _RET_IP_);
 
-        while (nbytes >= CHACHA20_BLOCK_SIZE) {
+        while (nbytes >= CHACHA_BLOCK_SIZE) {
                 extract_crng(buf);
-                buf += CHACHA20_BLOCK_SIZE;
-                nbytes -= CHACHA20_BLOCK_SIZE;
+                buf += CHACHA_BLOCK_SIZE;
+                nbytes -= CHACHA_BLOCK_SIZE;
         }
 
         if (nbytes > 0) {
@@ -1637,7 +1636,7 @@ static void _get_random_bytes(void *buf, int nbytes)
                 memcpy(buf, tmp, nbytes);
                 crng_backtrack_protect(tmp, nbytes);
         } else
-                crng_backtrack_protect(tmp, CHACHA20_BLOCK_SIZE);
+                crng_backtrack_protect(tmp, CHACHA_BLOCK_SIZE);
         memzero_explicit(tmp, sizeof(tmp));
 }
 
@@ -2208,8 +2207,8 @@ struct ctl_table random_table[] = {
 
 struct batched_entropy {
         union {
-                u64 entropy_u64[CHACHA20_BLOCK_SIZE / sizeof(u64)];
-                u32 entropy_u32[CHACHA20_BLOCK_SIZE / sizeof(u32)];
+                u64 entropy_u64[CHACHA_BLOCK_SIZE / sizeof(u64)];
+                u32 entropy_u32[CHACHA_BLOCK_SIZE / sizeof(u32)];
         };
         unsigned int position;
 };