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-rw-r--r--arch/s390/crypto/prng.c911
1 files changed, 911 insertions, 0 deletions
diff --git a/arch/s390/crypto/prng.c b/arch/s390/crypto/prng.c
new file mode 100644
index 000000000..a077087bc
--- /dev/null
+++ b/arch/s390/crypto/prng.c
@@ -0,0 +1,911 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright IBM Corp. 2006, 2015
+ * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
+ * Harald Freudenberger <freude@de.ibm.com>
+ * Driver for the s390 pseudo random number generator
+ */
+
+#define KMSG_COMPONENT "prng"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/fs.h>
+#include <linux/fips.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/mutex.h>
+#include <linux/cpufeature.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+#include <linux/sched/signal.h>
+
+#include <asm/debug.h>
+#include <linux/uaccess.h>
+#include <asm/timex.h>
+#include <asm/cpacf.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("IBM Corporation");
+MODULE_DESCRIPTION("s390 PRNG interface");
+
+
+#define PRNG_MODE_AUTO 0
+#define PRNG_MODE_TDES 1
+#define PRNG_MODE_SHA512 2
+
+static unsigned int prng_mode = PRNG_MODE_AUTO;
+module_param_named(mode, prng_mode, int, 0);
+MODULE_PARM_DESC(prng_mode, "PRNG mode: 0 - auto, 1 - TDES, 2 - SHA512");
+
+
+#define PRNG_CHUNKSIZE_TDES_MIN 8
+#define PRNG_CHUNKSIZE_TDES_MAX (64*1024)
+#define PRNG_CHUNKSIZE_SHA512_MIN 64
+#define PRNG_CHUNKSIZE_SHA512_MAX (64*1024)
+
+static unsigned int prng_chunk_size = 256;
+module_param_named(chunksize, prng_chunk_size, int, 0);
+MODULE_PARM_DESC(prng_chunk_size, "PRNG read chunk size in bytes");
+
+
+#define PRNG_RESEED_LIMIT_TDES 4096
+#define PRNG_RESEED_LIMIT_TDES_LOWER 4096
+#define PRNG_RESEED_LIMIT_SHA512 100000
+#define PRNG_RESEED_LIMIT_SHA512_LOWER 10000
+
+static unsigned int prng_reseed_limit;
+module_param_named(reseed_limit, prng_reseed_limit, int, 0);
+MODULE_PARM_DESC(prng_reseed_limit, "PRNG reseed limit");
+
+static bool trng_available;
+
+/*
+ * Any one who considers arithmetical methods of producing random digits is,
+ * of course, in a state of sin. -- John von Neumann
+ */
+
+static int prng_errorflag;
+
+#define PRNG_GEN_ENTROPY_FAILED 1
+#define PRNG_SELFTEST_FAILED 2
+#define PRNG_INSTANTIATE_FAILED 3
+#define PRNG_SEED_FAILED 4
+#define PRNG_RESEED_FAILED 5
+#define PRNG_GEN_FAILED 6
+
+struct prng_ws_s {
+ u8 parm_block[32];
+ u32 reseed_counter;
+ u64 byte_counter;
+};
+
+struct prno_ws_s {
+ u32 res;
+ u32 reseed_counter;
+ u64 stream_bytes;
+ u8 V[112];
+ u8 C[112];
+};
+
+struct prng_data_s {
+ struct mutex mutex;
+ union {
+ struct prng_ws_s prngws;
+ struct prno_ws_s prnows;
+ };
+ u8 *buf;
+ u32 rest;
+ u8 *prev;
+};
+
+static struct prng_data_s *prng_data;
+
+/* initial parameter block for tdes mode, copied from libica */
+static const u8 initial_parm_block[32] __initconst = {
+ 0x0F, 0x2B, 0x8E, 0x63, 0x8C, 0x8E, 0xD2, 0x52,
+ 0x64, 0xB7, 0xA0, 0x7B, 0x75, 0x28, 0xB8, 0xF4,
+ 0x75, 0x5F, 0xD2, 0xA6, 0x8D, 0x97, 0x11, 0xFF,
+ 0x49, 0xD8, 0x23, 0xF3, 0x7E, 0x21, 0xEC, 0xA0 };
+
+
+/*** helper functions ***/
+
+/*
+ * generate_entropy:
+ * This function fills a given buffer with random bytes. The entropy within
+ * the random bytes given back is assumed to have at least 50% - meaning
+ * a 64 bytes buffer has at least 64 * 8 / 2 = 256 bits of entropy.
+ * Within the function the entropy generation is done in junks of 64 bytes.
+ * So the caller should also ask for buffer fill in multiples of 64 bytes.
+ * The generation of the entropy is based on the assumption that every stckf()
+ * invocation produces 0.5 bits of entropy. To accumulate 256 bits of entropy
+ * at least 512 stckf() values are needed. The entropy relevant part of the
+ * stckf value is bit 51 (counting starts at the left with bit nr 0) so
+ * here we use the lower 4 bytes and exor the values into 2k of bufferspace.
+ * To be on the save side, if there is ever a problem with stckf() the
+ * other half of the page buffer is filled with bytes from urandom via
+ * get_random_bytes(), so this function consumes 2k of urandom for each
+ * requested 64 bytes output data. Finally the buffer page is condensed into
+ * a 64 byte value by hashing with a SHA512 hash.
+ */
+static int generate_entropy(u8 *ebuf, size_t nbytes)
+{
+ int n, ret = 0;
+ u8 *pg, pblock[80] = {
+ /* 8 x 64 bit init values */
+ 0x6A, 0x09, 0xE6, 0x67, 0xF3, 0xBC, 0xC9, 0x08,
+ 0xBB, 0x67, 0xAE, 0x85, 0x84, 0xCA, 0xA7, 0x3B,
+ 0x3C, 0x6E, 0xF3, 0x72, 0xFE, 0x94, 0xF8, 0x2B,
+ 0xA5, 0x4F, 0xF5, 0x3A, 0x5F, 0x1D, 0x36, 0xF1,
+ 0x51, 0x0E, 0x52, 0x7F, 0xAD, 0xE6, 0x82, 0xD1,
+ 0x9B, 0x05, 0x68, 0x8C, 0x2B, 0x3E, 0x6C, 0x1F,
+ 0x1F, 0x83, 0xD9, 0xAB, 0xFB, 0x41, 0xBD, 0x6B,
+ 0x5B, 0xE0, 0xCD, 0x19, 0x13, 0x7E, 0x21, 0x79,
+ /* 128 bit counter total message bit length */
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x00 };
+
+ /* allocate one page stckf buffer */
+ pg = (u8 *) __get_free_page(GFP_KERNEL);
+ if (!pg) {
+ prng_errorflag = PRNG_GEN_ENTROPY_FAILED;
+ return -ENOMEM;
+ }
+
+ /* fill the ebuf in chunks of 64 byte each */
+ while (nbytes) {
+ /* fill lower 2k with urandom bytes */
+ get_random_bytes(pg, PAGE_SIZE / 2);
+ /* exor upper 2k with 512 stckf values, offset 4 bytes each */
+ for (n = 0; n < 512; n++) {
+ int offset = (PAGE_SIZE / 2) + (n * 4) - 4;
+ u64 *p = (u64 *)(pg + offset);
+ *p ^= get_tod_clock_fast();
+ }
+ /* hash over the filled page */
+ cpacf_klmd(CPACF_KLMD_SHA_512, pblock, pg, PAGE_SIZE);
+ n = (nbytes < 64) ? nbytes : 64;
+ memcpy(ebuf, pblock, n);
+ ret += n;
+ ebuf += n;
+ nbytes -= n;
+ }
+
+ memzero_explicit(pblock, sizeof(pblock));
+ memzero_explicit(pg, PAGE_SIZE);
+ free_page((unsigned long)pg);
+ return ret;
+}
+
+
+/*** tdes functions ***/
+
+static void prng_tdes_add_entropy(void)
+{
+ __u64 entropy[4];
+ unsigned int i;
+
+ for (i = 0; i < 16; i++) {
+ cpacf_kmc(CPACF_KMC_PRNG, prng_data->prngws.parm_block,
+ (char *) entropy, (char *) entropy,
+ sizeof(entropy));
+ memcpy(prng_data->prngws.parm_block, entropy, sizeof(entropy));
+ }
+}
+
+
+static void prng_tdes_seed(int nbytes)
+{
+ char buf[16];
+ int i = 0;
+
+ BUG_ON(nbytes > sizeof(buf));
+
+ get_random_bytes(buf, nbytes);
+
+ /* Add the entropy */
+ while (nbytes >= 8) {
+ *((__u64 *)prng_data->prngws.parm_block) ^= *((__u64 *)(buf+i));
+ prng_tdes_add_entropy();
+ i += 8;
+ nbytes -= 8;
+ }
+ prng_tdes_add_entropy();
+ prng_data->prngws.reseed_counter = 0;
+}
+
+
+static int __init prng_tdes_instantiate(void)
+{
+ int datalen;
+
+ pr_debug("prng runs in TDES mode with "
+ "chunksize=%d and reseed_limit=%u\n",
+ prng_chunk_size, prng_reseed_limit);
+
+ /* memory allocation, prng_data struct init, mutex init */
+ datalen = sizeof(struct prng_data_s) + prng_chunk_size;
+ prng_data = kzalloc(datalen, GFP_KERNEL);
+ if (!prng_data) {
+ prng_errorflag = PRNG_INSTANTIATE_FAILED;
+ return -ENOMEM;
+ }
+ mutex_init(&prng_data->mutex);
+ prng_data->buf = ((u8 *)prng_data) + sizeof(struct prng_data_s);
+ memcpy(prng_data->prngws.parm_block, initial_parm_block, 32);
+
+ /* initialize the PRNG, add 128 bits of entropy */
+ prng_tdes_seed(16);
+
+ return 0;
+}
+
+
+static void prng_tdes_deinstantiate(void)
+{
+ pr_debug("The prng module stopped "
+ "after running in triple DES mode\n");
+ kfree_sensitive(prng_data);
+}
+
+
+/*** sha512 functions ***/
+
+static int __init prng_sha512_selftest(void)
+{
+ /* NIST DRBG testvector for Hash Drbg, Sha-512, Count #0 */
+ static const u8 seed[] __initconst = {
+ 0x6b, 0x50, 0xa7, 0xd8, 0xf8, 0xa5, 0x5d, 0x7a,
+ 0x3d, 0xf8, 0xbb, 0x40, 0xbc, 0xc3, 0xb7, 0x22,
+ 0xd8, 0x70, 0x8d, 0xe6, 0x7f, 0xda, 0x01, 0x0b,
+ 0x03, 0xc4, 0xc8, 0x4d, 0x72, 0x09, 0x6f, 0x8c,
+ 0x3e, 0xc6, 0x49, 0xcc, 0x62, 0x56, 0xd9, 0xfa,
+ 0x31, 0xdb, 0x7a, 0x29, 0x04, 0xaa, 0xf0, 0x25 };
+ static const u8 V0[] __initconst = {
+ 0x00, 0xad, 0xe3, 0x6f, 0x9a, 0x01, 0xc7, 0x76,
+ 0x61, 0x34, 0x35, 0xf5, 0x4e, 0x24, 0x74, 0x22,
+ 0x21, 0x9a, 0x29, 0x89, 0xc7, 0x93, 0x2e, 0x60,
+ 0x1e, 0xe8, 0x14, 0x24, 0x8d, 0xd5, 0x03, 0xf1,
+ 0x65, 0x5d, 0x08, 0x22, 0x72, 0xd5, 0xad, 0x95,
+ 0xe1, 0x23, 0x1e, 0x8a, 0xa7, 0x13, 0xd9, 0x2b,
+ 0x5e, 0xbc, 0xbb, 0x80, 0xab, 0x8d, 0xe5, 0x79,
+ 0xab, 0x5b, 0x47, 0x4e, 0xdd, 0xee, 0x6b, 0x03,
+ 0x8f, 0x0f, 0x5c, 0x5e, 0xa9, 0x1a, 0x83, 0xdd,
+ 0xd3, 0x88, 0xb2, 0x75, 0x4b, 0xce, 0x83, 0x36,
+ 0x57, 0x4b, 0xf1, 0x5c, 0xca, 0x7e, 0x09, 0xc0,
+ 0xd3, 0x89, 0xc6, 0xe0, 0xda, 0xc4, 0x81, 0x7e,
+ 0x5b, 0xf9, 0xe1, 0x01, 0xc1, 0x92, 0x05, 0xea,
+ 0xf5, 0x2f, 0xc6, 0xc6, 0xc7, 0x8f, 0xbc, 0xf4 };
+ static const u8 C0[] __initconst = {
+ 0x00, 0xf4, 0xa3, 0xe5, 0xa0, 0x72, 0x63, 0x95,
+ 0xc6, 0x4f, 0x48, 0xd0, 0x8b, 0x5b, 0x5f, 0x8e,
+ 0x6b, 0x96, 0x1f, 0x16, 0xed, 0xbc, 0x66, 0x94,
+ 0x45, 0x31, 0xd7, 0x47, 0x73, 0x22, 0xa5, 0x86,
+ 0xce, 0xc0, 0x4c, 0xac, 0x63, 0xb8, 0x39, 0x50,
+ 0xbf, 0xe6, 0x59, 0x6c, 0x38, 0x58, 0x99, 0x1f,
+ 0x27, 0xa7, 0x9d, 0x71, 0x2a, 0xb3, 0x7b, 0xf9,
+ 0xfb, 0x17, 0x86, 0xaa, 0x99, 0x81, 0xaa, 0x43,
+ 0xe4, 0x37, 0xd3, 0x1e, 0x6e, 0xe5, 0xe6, 0xee,
+ 0xc2, 0xed, 0x95, 0x4f, 0x53, 0x0e, 0x46, 0x8a,
+ 0xcc, 0x45, 0xa5, 0xdb, 0x69, 0x0d, 0x81, 0xc9,
+ 0x32, 0x92, 0xbc, 0x8f, 0x33, 0xe6, 0xf6, 0x09,
+ 0x7c, 0x8e, 0x05, 0x19, 0x0d, 0xf1, 0xb6, 0xcc,
+ 0xf3, 0x02, 0x21, 0x90, 0x25, 0xec, 0xed, 0x0e };
+ static const u8 random[] __initconst = {
+ 0x95, 0xb7, 0xf1, 0x7e, 0x98, 0x02, 0xd3, 0x57,
+ 0x73, 0x92, 0xc6, 0xa9, 0xc0, 0x80, 0x83, 0xb6,
+ 0x7d, 0xd1, 0x29, 0x22, 0x65, 0xb5, 0xf4, 0x2d,
+ 0x23, 0x7f, 0x1c, 0x55, 0xbb, 0x9b, 0x10, 0xbf,
+ 0xcf, 0xd8, 0x2c, 0x77, 0xa3, 0x78, 0xb8, 0x26,
+ 0x6a, 0x00, 0x99, 0x14, 0x3b, 0x3c, 0x2d, 0x64,
+ 0x61, 0x1e, 0xee, 0xb6, 0x9a, 0xcd, 0xc0, 0x55,
+ 0x95, 0x7c, 0x13, 0x9e, 0x8b, 0x19, 0x0c, 0x7a,
+ 0x06, 0x95, 0x5f, 0x2c, 0x79, 0x7c, 0x27, 0x78,
+ 0xde, 0x94, 0x03, 0x96, 0xa5, 0x01, 0xf4, 0x0e,
+ 0x91, 0x39, 0x6a, 0xcf, 0x8d, 0x7e, 0x45, 0xeb,
+ 0xdb, 0xb5, 0x3b, 0xbf, 0x8c, 0x97, 0x52, 0x30,
+ 0xd2, 0xf0, 0xff, 0x91, 0x06, 0xc7, 0x61, 0x19,
+ 0xae, 0x49, 0x8e, 0x7f, 0xbc, 0x03, 0xd9, 0x0f,
+ 0x8e, 0x4c, 0x51, 0x62, 0x7a, 0xed, 0x5c, 0x8d,
+ 0x42, 0x63, 0xd5, 0xd2, 0xb9, 0x78, 0x87, 0x3a,
+ 0x0d, 0xe5, 0x96, 0xee, 0x6d, 0xc7, 0xf7, 0xc2,
+ 0x9e, 0x37, 0xee, 0xe8, 0xb3, 0x4c, 0x90, 0xdd,
+ 0x1c, 0xf6, 0xa9, 0xdd, 0xb2, 0x2b, 0x4c, 0xbd,
+ 0x08, 0x6b, 0x14, 0xb3, 0x5d, 0xe9, 0x3d, 0xa2,
+ 0xd5, 0xcb, 0x18, 0x06, 0x69, 0x8c, 0xbd, 0x7b,
+ 0xbb, 0x67, 0xbf, 0xe3, 0xd3, 0x1f, 0xd2, 0xd1,
+ 0xdb, 0xd2, 0xa1, 0xe0, 0x58, 0xa3, 0xeb, 0x99,
+ 0xd7, 0xe5, 0x1f, 0x1a, 0x93, 0x8e, 0xed, 0x5e,
+ 0x1c, 0x1d, 0xe2, 0x3a, 0x6b, 0x43, 0x45, 0xd3,
+ 0x19, 0x14, 0x09, 0xf9, 0x2f, 0x39, 0xb3, 0x67,
+ 0x0d, 0x8d, 0xbf, 0xb6, 0x35, 0xd8, 0xe6, 0xa3,
+ 0x69, 0x32, 0xd8, 0x10, 0x33, 0xd1, 0x44, 0x8d,
+ 0x63, 0xb4, 0x03, 0xdd, 0xf8, 0x8e, 0x12, 0x1b,
+ 0x6e, 0x81, 0x9a, 0xc3, 0x81, 0x22, 0x6c, 0x13,
+ 0x21, 0xe4, 0xb0, 0x86, 0x44, 0xf6, 0x72, 0x7c,
+ 0x36, 0x8c, 0x5a, 0x9f, 0x7a, 0x4b, 0x3e, 0xe2 };
+
+ u8 buf[sizeof(random)];
+ struct prno_ws_s ws;
+
+ memset(&ws, 0, sizeof(ws));
+
+ /* initial seed */
+ cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED,
+ &ws, NULL, 0, seed, sizeof(seed));
+
+ /* check working states V and C */
+ if (memcmp(ws.V, V0, sizeof(V0)) != 0
+ || memcmp(ws.C, C0, sizeof(C0)) != 0) {
+ pr_err("The prng self test state test "
+ "for the SHA-512 mode failed\n");
+ prng_errorflag = PRNG_SELFTEST_FAILED;
+ return -EIO;
+ }
+
+ /* generate random bytes */
+ cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN,
+ &ws, buf, sizeof(buf), NULL, 0);
+ cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN,
+ &ws, buf, sizeof(buf), NULL, 0);
+
+ /* check against expected data */
+ if (memcmp(buf, random, sizeof(random)) != 0) {
+ pr_err("The prng self test data test "
+ "for the SHA-512 mode failed\n");
+ prng_errorflag = PRNG_SELFTEST_FAILED;
+ return -EIO;
+ }
+
+ return 0;
+}
+
+
+static int __init prng_sha512_instantiate(void)
+{
+ int ret, datalen, seedlen;
+ u8 seed[128 + 16];
+
+ pr_debug("prng runs in SHA-512 mode "
+ "with chunksize=%d and reseed_limit=%u\n",
+ prng_chunk_size, prng_reseed_limit);
+
+ /* memory allocation, prng_data struct init, mutex init */
+ datalen = sizeof(struct prng_data_s) + prng_chunk_size;
+ if (fips_enabled)
+ datalen += prng_chunk_size;
+ prng_data = kzalloc(datalen, GFP_KERNEL);
+ if (!prng_data) {
+ prng_errorflag = PRNG_INSTANTIATE_FAILED;
+ return -ENOMEM;
+ }
+ mutex_init(&prng_data->mutex);
+ prng_data->buf = ((u8 *)prng_data) + sizeof(struct prng_data_s);
+
+ /* selftest */
+ ret = prng_sha512_selftest();
+ if (ret)
+ goto outfree;
+
+ /* generate initial seed, we need at least 256 + 128 bits entropy. */
+ if (trng_available) {
+ /*
+ * Trng available, so use it. The trng works in chunks of
+ * 32 bytes and produces 100% entropy. So we pull 64 bytes
+ * which gives us 512 bits entropy.
+ */
+ seedlen = 2 * 32;
+ cpacf_trng(NULL, 0, seed, seedlen);
+ } else {
+ /*
+ * No trng available, so use the generate_entropy() function.
+ * This function works in 64 byte junks and produces
+ * 50% entropy. So we pull 2*64 bytes which gives us 512 bits
+ * of entropy.
+ */
+ seedlen = 2 * 64;
+ ret = generate_entropy(seed, seedlen);
+ if (ret != seedlen)
+ goto outfree;
+ }
+
+ /* append the seed by 16 bytes of unique nonce */
+ store_tod_clock_ext((union tod_clock *)(seed + seedlen));
+ seedlen += 16;
+
+ /* now initial seed of the prno drng */
+ cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED,
+ &prng_data->prnows, NULL, 0, seed, seedlen);
+ memzero_explicit(seed, sizeof(seed));
+
+ /* if fips mode is enabled, generate a first block of random
+ bytes for the FIPS 140-2 Conditional Self Test */
+ if (fips_enabled) {
+ prng_data->prev = prng_data->buf + prng_chunk_size;
+ cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN,
+ &prng_data->prnows,
+ prng_data->prev, prng_chunk_size, NULL, 0);
+ }
+
+ return 0;
+
+outfree:
+ kfree(prng_data);
+ return ret;
+}
+
+
+static void prng_sha512_deinstantiate(void)
+{
+ pr_debug("The prng module stopped after running in SHA-512 mode\n");
+ kfree_sensitive(prng_data);
+}
+
+
+static int prng_sha512_reseed(void)
+{
+ int ret, seedlen;
+ u8 seed[64];
+
+ /* We need at least 256 bits of fresh entropy for reseeding */
+ if (trng_available) {
+ /* trng produces 256 bits entropy in 32 bytes */
+ seedlen = 32;
+ cpacf_trng(NULL, 0, seed, seedlen);
+ } else {
+ /* generate_entropy() produces 256 bits entropy in 64 bytes */
+ seedlen = 64;
+ ret = generate_entropy(seed, seedlen);
+ if (ret != sizeof(seed))
+ return ret;
+ }
+
+ /* do a reseed of the prno drng with this bytestring */
+ cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED,
+ &prng_data->prnows, NULL, 0, seed, seedlen);
+ memzero_explicit(seed, sizeof(seed));
+
+ return 0;
+}
+
+
+static int prng_sha512_generate(u8 *buf, size_t nbytes)
+{
+ int ret;
+
+ /* reseed needed ? */
+ if (prng_data->prnows.reseed_counter > prng_reseed_limit) {
+ ret = prng_sha512_reseed();
+ if (ret)
+ return ret;
+ }
+
+ /* PRNO generate */
+ cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN,
+ &prng_data->prnows, buf, nbytes, NULL, 0);
+
+ /* FIPS 140-2 Conditional Self Test */
+ if (fips_enabled) {
+ if (!memcmp(prng_data->prev, buf, nbytes)) {
+ prng_errorflag = PRNG_GEN_FAILED;
+ return -EILSEQ;
+ }
+ memcpy(prng_data->prev, buf, nbytes);
+ }
+
+ return nbytes;
+}
+
+
+/*** file io functions ***/
+
+static int prng_open(struct inode *inode, struct file *file)
+{
+ return nonseekable_open(inode, file);
+}
+
+
+static ssize_t prng_tdes_read(struct file *file, char __user *ubuf,
+ size_t nbytes, loff_t *ppos)
+{
+ int chunk, n, ret = 0;
+
+ /* lock prng_data struct */
+ if (mutex_lock_interruptible(&prng_data->mutex))
+ return -ERESTARTSYS;
+
+ while (nbytes) {
+ if (need_resched()) {
+ if (signal_pending(current)) {
+ if (ret == 0)
+ ret = -ERESTARTSYS;
+ break;
+ }
+ /* give mutex free before calling schedule() */
+ mutex_unlock(&prng_data->mutex);
+ schedule();
+ /* occupy mutex again */
+ if (mutex_lock_interruptible(&prng_data->mutex)) {
+ if (ret == 0)
+ ret = -ERESTARTSYS;
+ return ret;
+ }
+ }
+
+ /*
+ * we lose some random bytes if an attacker issues
+ * reads < 8 bytes, but we don't care
+ */
+ chunk = min_t(int, nbytes, prng_chunk_size);
+
+ /* PRNG only likes multiples of 8 bytes */
+ n = (chunk + 7) & -8;
+
+ if (prng_data->prngws.reseed_counter > prng_reseed_limit)
+ prng_tdes_seed(8);
+
+ /* if the CPU supports PRNG stckf is present too */
+ *((unsigned long long *)prng_data->buf) = get_tod_clock_fast();
+
+ /*
+ * Beside the STCKF the input for the TDES-EDE is the output
+ * of the last operation. We differ here from X9.17 since we
+ * only store one timestamp into the buffer. Padding the whole
+ * buffer with timestamps does not improve security, since
+ * successive stckf have nearly constant offsets.
+ * If an attacker knows the first timestamp it would be
+ * trivial to guess the additional values. One timestamp
+ * is therefore enough and still guarantees unique input values.
+ *
+ * Note: you can still get strict X9.17 conformity by setting
+ * prng_chunk_size to 8 bytes.
+ */
+ cpacf_kmc(CPACF_KMC_PRNG, prng_data->prngws.parm_block,
+ prng_data->buf, prng_data->buf, n);
+
+ prng_data->prngws.byte_counter += n;
+ prng_data->prngws.reseed_counter += n;
+
+ if (copy_to_user(ubuf, prng_data->buf, chunk)) {
+ ret = -EFAULT;
+ break;
+ }
+
+ nbytes -= chunk;
+ ret += chunk;
+ ubuf += chunk;
+ }
+
+ /* unlock prng_data struct */
+ mutex_unlock(&prng_data->mutex);
+
+ return ret;
+}
+
+
+static ssize_t prng_sha512_read(struct file *file, char __user *ubuf,
+ size_t nbytes, loff_t *ppos)
+{
+ int n, ret = 0;
+ u8 *p;
+
+ /* if errorflag is set do nothing and return 'broken pipe' */
+ if (prng_errorflag)
+ return -EPIPE;
+
+ /* lock prng_data struct */
+ if (mutex_lock_interruptible(&prng_data->mutex))
+ return -ERESTARTSYS;
+
+ while (nbytes) {
+ if (need_resched()) {
+ if (signal_pending(current)) {
+ if (ret == 0)
+ ret = -ERESTARTSYS;
+ break;
+ }
+ /* give mutex free before calling schedule() */
+ mutex_unlock(&prng_data->mutex);
+ schedule();
+ /* occopy mutex again */
+ if (mutex_lock_interruptible(&prng_data->mutex)) {
+ if (ret == 0)
+ ret = -ERESTARTSYS;
+ return ret;
+ }
+ }
+ if (prng_data->rest) {
+ /* push left over random bytes from the previous read */
+ p = prng_data->buf + prng_chunk_size - prng_data->rest;
+ n = (nbytes < prng_data->rest) ?
+ nbytes : prng_data->rest;
+ prng_data->rest -= n;
+ } else {
+ /* generate one chunk of random bytes into read buf */
+ p = prng_data->buf;
+ n = prng_sha512_generate(p, prng_chunk_size);
+ if (n < 0) {
+ ret = n;
+ break;
+ }
+ if (nbytes < prng_chunk_size) {
+ n = nbytes;
+ prng_data->rest = prng_chunk_size - n;
+ } else {
+ n = prng_chunk_size;
+ prng_data->rest = 0;
+ }
+ }
+ if (copy_to_user(ubuf, p, n)) {
+ ret = -EFAULT;
+ break;
+ }
+ memzero_explicit(p, n);
+ ubuf += n;
+ nbytes -= n;
+ ret += n;
+ }
+
+ /* unlock prng_data struct */
+ mutex_unlock(&prng_data->mutex);
+
+ return ret;
+}
+
+
+/*** sysfs stuff ***/
+
+static const struct file_operations prng_sha512_fops = {
+ .owner = THIS_MODULE,
+ .open = &prng_open,
+ .release = NULL,
+ .read = &prng_sha512_read,
+ .llseek = noop_llseek,
+};
+static const struct file_operations prng_tdes_fops = {
+ .owner = THIS_MODULE,
+ .open = &prng_open,
+ .release = NULL,
+ .read = &prng_tdes_read,
+ .llseek = noop_llseek,
+};
+
+/* chunksize attribute (ro) */
+static ssize_t prng_chunksize_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return scnprintf(buf, PAGE_SIZE, "%u\n", prng_chunk_size);
+}
+static DEVICE_ATTR(chunksize, 0444, prng_chunksize_show, NULL);
+
+/* counter attribute (ro) */
+static ssize_t prng_counter_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ u64 counter;
+
+ if (mutex_lock_interruptible(&prng_data->mutex))
+ return -ERESTARTSYS;
+ if (prng_mode == PRNG_MODE_SHA512)
+ counter = prng_data->prnows.stream_bytes;
+ else
+ counter = prng_data->prngws.byte_counter;
+ mutex_unlock(&prng_data->mutex);
+
+ return scnprintf(buf, PAGE_SIZE, "%llu\n", counter);
+}
+static DEVICE_ATTR(byte_counter, 0444, prng_counter_show, NULL);
+
+/* errorflag attribute (ro) */
+static ssize_t prng_errorflag_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return scnprintf(buf, PAGE_SIZE, "%d\n", prng_errorflag);
+}
+static DEVICE_ATTR(errorflag, 0444, prng_errorflag_show, NULL);
+
+/* mode attribute (ro) */
+static ssize_t prng_mode_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ if (prng_mode == PRNG_MODE_TDES)
+ return scnprintf(buf, PAGE_SIZE, "TDES\n");
+ else
+ return scnprintf(buf, PAGE_SIZE, "SHA512\n");
+}
+static DEVICE_ATTR(mode, 0444, prng_mode_show, NULL);
+
+/* reseed attribute (w) */
+static ssize_t prng_reseed_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ if (mutex_lock_interruptible(&prng_data->mutex))
+ return -ERESTARTSYS;
+ prng_sha512_reseed();
+ mutex_unlock(&prng_data->mutex);
+
+ return count;
+}
+static DEVICE_ATTR(reseed, 0200, NULL, prng_reseed_store);
+
+/* reseed limit attribute (rw) */
+static ssize_t prng_reseed_limit_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return scnprintf(buf, PAGE_SIZE, "%u\n", prng_reseed_limit);
+}
+static ssize_t prng_reseed_limit_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ unsigned limit;
+
+ if (sscanf(buf, "%u\n", &limit) != 1)
+ return -EINVAL;
+
+ if (prng_mode == PRNG_MODE_SHA512) {
+ if (limit < PRNG_RESEED_LIMIT_SHA512_LOWER)
+ return -EINVAL;
+ } else {
+ if (limit < PRNG_RESEED_LIMIT_TDES_LOWER)
+ return -EINVAL;
+ }
+
+ prng_reseed_limit = limit;
+
+ return count;
+}
+static DEVICE_ATTR(reseed_limit, 0644,
+ prng_reseed_limit_show, prng_reseed_limit_store);
+
+/* strength attribute (ro) */
+static ssize_t prng_strength_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return scnprintf(buf, PAGE_SIZE, "256\n");
+}
+static DEVICE_ATTR(strength, 0444, prng_strength_show, NULL);
+
+static struct attribute *prng_sha512_dev_attrs[] = {
+ &dev_attr_errorflag.attr,
+ &dev_attr_chunksize.attr,
+ &dev_attr_byte_counter.attr,
+ &dev_attr_mode.attr,
+ &dev_attr_reseed.attr,
+ &dev_attr_reseed_limit.attr,
+ &dev_attr_strength.attr,
+ NULL
+};
+ATTRIBUTE_GROUPS(prng_sha512_dev);
+
+static struct attribute *prng_tdes_dev_attrs[] = {
+ &dev_attr_chunksize.attr,
+ &dev_attr_byte_counter.attr,
+ &dev_attr_mode.attr,
+ NULL
+};
+ATTRIBUTE_GROUPS(prng_tdes_dev);
+
+static struct miscdevice prng_sha512_dev = {
+ .name = "prandom",
+ .minor = MISC_DYNAMIC_MINOR,
+ .mode = 0644,
+ .fops = &prng_sha512_fops,
+ .groups = prng_sha512_dev_groups,
+};
+
+static struct miscdevice prng_tdes_dev = {
+ .name = "prandom",
+ .minor = MISC_DYNAMIC_MINOR,
+ .mode = 0644,
+ .fops = &prng_tdes_fops,
+ .groups = prng_tdes_dev_groups,
+};
+
+
+/*** module init and exit ***/
+
+static int __init prng_init(void)
+{
+ int ret;
+
+ /* check if the CPU has a PRNG */
+ if (!cpacf_query_func(CPACF_KMC, CPACF_KMC_PRNG))
+ return -ENODEV;
+
+ /* check if TRNG subfunction is available */
+ if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
+ trng_available = true;
+
+ /* choose prng mode */
+ if (prng_mode != PRNG_MODE_TDES) {
+ /* check for MSA5 support for PRNO operations */
+ if (!cpacf_query_func(CPACF_PRNO, CPACF_PRNO_SHA512_DRNG_GEN)) {
+ if (prng_mode == PRNG_MODE_SHA512) {
+ pr_err("The prng module cannot "
+ "start in SHA-512 mode\n");
+ return -ENODEV;
+ }
+ prng_mode = PRNG_MODE_TDES;
+ } else
+ prng_mode = PRNG_MODE_SHA512;
+ }
+
+ if (prng_mode == PRNG_MODE_SHA512) {
+
+ /* SHA512 mode */
+
+ if (prng_chunk_size < PRNG_CHUNKSIZE_SHA512_MIN
+ || prng_chunk_size > PRNG_CHUNKSIZE_SHA512_MAX)
+ return -EINVAL;
+ prng_chunk_size = (prng_chunk_size + 0x3f) & ~0x3f;
+
+ if (prng_reseed_limit == 0)
+ prng_reseed_limit = PRNG_RESEED_LIMIT_SHA512;
+ else if (prng_reseed_limit < PRNG_RESEED_LIMIT_SHA512_LOWER)
+ return -EINVAL;
+
+ ret = prng_sha512_instantiate();
+ if (ret)
+ goto out;
+
+ ret = misc_register(&prng_sha512_dev);
+ if (ret) {
+ prng_sha512_deinstantiate();
+ goto out;
+ }
+
+ } else {
+
+ /* TDES mode */
+
+ if (prng_chunk_size < PRNG_CHUNKSIZE_TDES_MIN
+ || prng_chunk_size > PRNG_CHUNKSIZE_TDES_MAX)
+ return -EINVAL;
+ prng_chunk_size = (prng_chunk_size + 0x07) & ~0x07;
+
+ if (prng_reseed_limit == 0)
+ prng_reseed_limit = PRNG_RESEED_LIMIT_TDES;
+ else if (prng_reseed_limit < PRNG_RESEED_LIMIT_TDES_LOWER)
+ return -EINVAL;
+
+ ret = prng_tdes_instantiate();
+ if (ret)
+ goto out;
+
+ ret = misc_register(&prng_tdes_dev);
+ if (ret) {
+ prng_tdes_deinstantiate();
+ goto out;
+ }
+ }
+
+out:
+ return ret;
+}
+
+
+static void __exit prng_exit(void)
+{
+ if (prng_mode == PRNG_MODE_SHA512) {
+ misc_deregister(&prng_sha512_dev);
+ prng_sha512_deinstantiate();
+ } else {
+ misc_deregister(&prng_tdes_dev);
+ prng_tdes_deinstantiate();
+ }
+}
+
+module_cpu_feature_match(S390_CPU_FEATURE_MSA, prng_init);
+module_exit(prng_exit);
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-02 21:52:28 +0000