Revision 2f8619846755176a6720c71d580ffd09394a74bc authored by Mian Yousaf Kaukab on 29 June 2021, 15:06:43 UTC, committed by Alexandre Belloni on 10 July 2021, 00:58:31 UTC
commit 03623b4b041c ("rtc: pcf2127: add tamper detection support")
added support for timestamp interrupts. However they are not being
handled in the irq handler. If a timestamp interrupt occurs it
results in kernel disabling the interrupt and displaying the call
trace:

[  121.145580] irq 78: nobody cared (try booting with the "irqpoll" option)
...
[  121.238087] [<00000000c4d69393>] irq_default_primary_handler threaded [<000000000a90d25b>] pcf2127_rtc_irq [rtc_pcf2127]
[  121.248971] Disabling IRQ #78

Handle timestamp interrupts in pcf2127_rtc_irq(). Save time stamp
before clearing TSF1 and TSF2 flags so that it can't be overwritten.
Set a flag to mark if the timestamp is valid and only report to sysfs
if the flag is set. To mimic the hardware behavior, don’t save
another timestamp until the first one has been read by the userspace.

However, if the alarm irq is not configured, keep the old way of
handling timestamp interrupt in the timestamp0 sysfs calls.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
Reviewed-by: Bruno Thomsen <bruno.thomsen@gmail.com>
Tested-by: Bruno Thomsen <bruno.thomsen@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210629150643.31551-1-ykaukab@suse.de
1 parent 37aadf9
Raw File
ecdsa.c
// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (c) 2021 IBM Corporation
 */

#include <linux/module.h>
#include <crypto/internal/akcipher.h>
#include <crypto/akcipher.h>
#include <crypto/ecdh.h>
#include <linux/asn1_decoder.h>
#include <linux/scatterlist.h>

#include "ecc.h"
#include "ecdsasignature.asn1.h"

struct ecc_ctx {
	unsigned int curve_id;
	const struct ecc_curve *curve;

	bool pub_key_set;
	u64 x[ECC_MAX_DIGITS]; /* pub key x and y coordinates */
	u64 y[ECC_MAX_DIGITS];
	struct ecc_point pub_key;
};

struct ecdsa_signature_ctx {
	const struct ecc_curve *curve;
	u64 r[ECC_MAX_DIGITS];
	u64 s[ECC_MAX_DIGITS];
};

/*
 * Get the r and s components of a signature from the X509 certificate.
 */
static int ecdsa_get_signature_rs(u64 *dest, size_t hdrlen, unsigned char tag,
				  const void *value, size_t vlen, unsigned int ndigits)
{
	size_t keylen = ndigits * sizeof(u64);
	ssize_t diff = vlen - keylen;
	const char *d = value;
	u8 rs[ECC_MAX_BYTES];

	if (!value || !vlen)
		return -EINVAL;

	/* diff = 0: 'value' has exacly the right size
	 * diff > 0: 'value' has too many bytes; one leading zero is allowed that
	 *           makes the value a positive integer; error on more
	 * diff < 0: 'value' is missing leading zeros, which we add
	 */
	if (diff > 0) {
		/* skip over leading zeros that make 'value' a positive int */
		if (*d == 0) {
			vlen -= 1;
			diff--;
			d++;
		}
		if (diff)
			return -EINVAL;
	}
	if (-diff >= keylen)
		return -EINVAL;

	if (diff) {
		/* leading zeros not given in 'value' */
		memset(rs, 0, -diff);
	}

	memcpy(&rs[-diff], d, vlen);

	ecc_swap_digits((u64 *)rs, dest, ndigits);

	return 0;
}

int ecdsa_get_signature_r(void *context, size_t hdrlen, unsigned char tag,
			  const void *value, size_t vlen)
{
	struct ecdsa_signature_ctx *sig = context;

	return ecdsa_get_signature_rs(sig->r, hdrlen, tag, value, vlen,
				      sig->curve->g.ndigits);
}

int ecdsa_get_signature_s(void *context, size_t hdrlen, unsigned char tag,
			  const void *value, size_t vlen)
{
	struct ecdsa_signature_ctx *sig = context;

	return ecdsa_get_signature_rs(sig->s, hdrlen, tag, value, vlen,
				      sig->curve->g.ndigits);
}

static int _ecdsa_verify(struct ecc_ctx *ctx, const u64 *hash, const u64 *r, const u64 *s)
{
	const struct ecc_curve *curve = ctx->curve;
	unsigned int ndigits = curve->g.ndigits;
	u64 s1[ECC_MAX_DIGITS];
	u64 u1[ECC_MAX_DIGITS];
	u64 u2[ECC_MAX_DIGITS];
	u64 x1[ECC_MAX_DIGITS];
	u64 y1[ECC_MAX_DIGITS];
	struct ecc_point res = ECC_POINT_INIT(x1, y1, ndigits);

	/* 0 < r < n  and 0 < s < n */
	if (vli_is_zero(r, ndigits) || vli_cmp(r, curve->n, ndigits) >= 0 ||
	    vli_is_zero(s, ndigits) || vli_cmp(s, curve->n, ndigits) >= 0)
		return -EBADMSG;

	/* hash is given */
	pr_devel("hash : %016llx %016llx ... %016llx\n",
		 hash[ndigits - 1], hash[ndigits - 2], hash[0]);

	/* s1 = (s^-1) mod n */
	vli_mod_inv(s1, s, curve->n, ndigits);
	/* u1 = (hash * s1) mod n */
	vli_mod_mult_slow(u1, hash, s1, curve->n, ndigits);
	/* u2 = (r * s1) mod n */
	vli_mod_mult_slow(u2, r, s1, curve->n, ndigits);
	/* res = u1*G + u2 * pub_key */
	ecc_point_mult_shamir(&res, u1, &curve->g, u2, &ctx->pub_key, curve);

	/* res.x = res.x mod n (if res.x > order) */
	if (unlikely(vli_cmp(res.x, curve->n, ndigits) == 1))
		/* faster alternative for NIST p384, p256 & p192 */
		vli_sub(res.x, res.x, curve->n, ndigits);

	if (!vli_cmp(res.x, r, ndigits))
		return 0;

	return -EKEYREJECTED;
}

/*
 * Verify an ECDSA signature.
 */
static int ecdsa_verify(struct akcipher_request *req)
{
	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
	struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
	size_t keylen = ctx->curve->g.ndigits * sizeof(u64);
	struct ecdsa_signature_ctx sig_ctx = {
		.curve = ctx->curve,
	};
	u8 rawhash[ECC_MAX_BYTES];
	u64 hash[ECC_MAX_DIGITS];
	unsigned char *buffer;
	ssize_t diff;
	int ret;

	if (unlikely(!ctx->pub_key_set))
		return -EINVAL;

	buffer = kmalloc(req->src_len + req->dst_len, GFP_KERNEL);
	if (!buffer)
		return -ENOMEM;

	sg_pcopy_to_buffer(req->src,
		sg_nents_for_len(req->src, req->src_len + req->dst_len),
		buffer, req->src_len + req->dst_len, 0);

	ret = asn1_ber_decoder(&ecdsasignature_decoder, &sig_ctx,
			       buffer, req->src_len);
	if (ret < 0)
		goto error;

	/* if the hash is shorter then we will add leading zeros to fit to ndigits */
	diff = keylen - req->dst_len;
	if (diff >= 0) {
		if (diff)
			memset(rawhash, 0, diff);
		memcpy(&rawhash[diff], buffer + req->src_len, req->dst_len);
	} else if (diff < 0) {
		/* given hash is longer, we take the left-most bytes */
		memcpy(&rawhash, buffer + req->src_len, keylen);
	}

	ecc_swap_digits((u64 *)rawhash, hash, ctx->curve->g.ndigits);

	ret = _ecdsa_verify(ctx, hash, sig_ctx.r, sig_ctx.s);

error:
	kfree(buffer);

	return ret;
}

static int ecdsa_ecc_ctx_init(struct ecc_ctx *ctx, unsigned int curve_id)
{
	ctx->curve_id = curve_id;
	ctx->curve = ecc_get_curve(curve_id);
	if (!ctx->curve)
		return -EINVAL;

	return 0;
}


static void ecdsa_ecc_ctx_deinit(struct ecc_ctx *ctx)
{
	ctx->pub_key_set = false;
}

static int ecdsa_ecc_ctx_reset(struct ecc_ctx *ctx)
{
	unsigned int curve_id = ctx->curve_id;
	int ret;

	ecdsa_ecc_ctx_deinit(ctx);
	ret = ecdsa_ecc_ctx_init(ctx, curve_id);
	if (ret == 0)
		ctx->pub_key = ECC_POINT_INIT(ctx->x, ctx->y,
					      ctx->curve->g.ndigits);
	return ret;
}

/*
 * Set the public key given the raw uncompressed key data from an X509
 * certificate. The key data contain the concatenated X and Y coordinates of
 * the public key.
 */
static int ecdsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, unsigned int keylen)
{
	struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
	const unsigned char *d = key;
	const u64 *digits = (const u64 *)&d[1];
	unsigned int ndigits;
	int ret;

	ret = ecdsa_ecc_ctx_reset(ctx);
	if (ret < 0)
		return ret;

	if (keylen < 1 || (((keylen - 1) >> 1) % sizeof(u64)) != 0)
		return -EINVAL;
	/* we only accept uncompressed format indicated by '4' */
	if (d[0] != 4)
		return -EINVAL;

	keylen--;
	ndigits = (keylen >> 1) / sizeof(u64);
	if (ndigits != ctx->curve->g.ndigits)
		return -EINVAL;

	ecc_swap_digits(digits, ctx->pub_key.x, ndigits);
	ecc_swap_digits(&digits[ndigits], ctx->pub_key.y, ndigits);
	ret = ecc_is_pubkey_valid_full(ctx->curve, &ctx->pub_key);

	ctx->pub_key_set = ret == 0;

	return ret;
}

static void ecdsa_exit_tfm(struct crypto_akcipher *tfm)
{
	struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);

	ecdsa_ecc_ctx_deinit(ctx);
}

static unsigned int ecdsa_max_size(struct crypto_akcipher *tfm)
{
	struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);

	return ctx->pub_key.ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
}

static int ecdsa_nist_p384_init_tfm(struct crypto_akcipher *tfm)
{
	struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);

	return ecdsa_ecc_ctx_init(ctx, ECC_CURVE_NIST_P384);
}

static struct akcipher_alg ecdsa_nist_p384 = {
	.verify = ecdsa_verify,
	.set_pub_key = ecdsa_set_pub_key,
	.max_size = ecdsa_max_size,
	.init = ecdsa_nist_p384_init_tfm,
	.exit = ecdsa_exit_tfm,
	.base = {
		.cra_name = "ecdsa-nist-p384",
		.cra_driver_name = "ecdsa-nist-p384-generic",
		.cra_priority = 100,
		.cra_module = THIS_MODULE,
		.cra_ctxsize = sizeof(struct ecc_ctx),
	},
};

static int ecdsa_nist_p256_init_tfm(struct crypto_akcipher *tfm)
{
	struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);

	return ecdsa_ecc_ctx_init(ctx, ECC_CURVE_NIST_P256);
}

static struct akcipher_alg ecdsa_nist_p256 = {
	.verify = ecdsa_verify,
	.set_pub_key = ecdsa_set_pub_key,
	.max_size = ecdsa_max_size,
	.init = ecdsa_nist_p256_init_tfm,
	.exit = ecdsa_exit_tfm,
	.base = {
		.cra_name = "ecdsa-nist-p256",
		.cra_driver_name = "ecdsa-nist-p256-generic",
		.cra_priority = 100,
		.cra_module = THIS_MODULE,
		.cra_ctxsize = sizeof(struct ecc_ctx),
	},
};

static int ecdsa_nist_p192_init_tfm(struct crypto_akcipher *tfm)
{
	struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);

	return ecdsa_ecc_ctx_init(ctx, ECC_CURVE_NIST_P192);
}

static struct akcipher_alg ecdsa_nist_p192 = {
	.verify = ecdsa_verify,
	.set_pub_key = ecdsa_set_pub_key,
	.max_size = ecdsa_max_size,
	.init = ecdsa_nist_p192_init_tfm,
	.exit = ecdsa_exit_tfm,
	.base = {
		.cra_name = "ecdsa-nist-p192",
		.cra_driver_name = "ecdsa-nist-p192-generic",
		.cra_priority = 100,
		.cra_module = THIS_MODULE,
		.cra_ctxsize = sizeof(struct ecc_ctx),
	},
};
static bool ecdsa_nist_p192_registered;

static int ecdsa_init(void)
{
	int ret;

	/* NIST p192 may not be available in FIPS mode */
	ret = crypto_register_akcipher(&ecdsa_nist_p192);
	ecdsa_nist_p192_registered = ret == 0;

	ret = crypto_register_akcipher(&ecdsa_nist_p256);
	if (ret)
		goto nist_p256_error;

	ret = crypto_register_akcipher(&ecdsa_nist_p384);
	if (ret)
		goto nist_p384_error;

	return 0;

nist_p384_error:
	crypto_unregister_akcipher(&ecdsa_nist_p256);

nist_p256_error:
	if (ecdsa_nist_p192_registered)
		crypto_unregister_akcipher(&ecdsa_nist_p192);
	return ret;
}

static void ecdsa_exit(void)
{
	if (ecdsa_nist_p192_registered)
		crypto_unregister_akcipher(&ecdsa_nist_p192);
	crypto_unregister_akcipher(&ecdsa_nist_p256);
	crypto_unregister_akcipher(&ecdsa_nist_p384);
}

subsys_initcall(ecdsa_init);
module_exit(ecdsa_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Stefan Berger <stefanb@linux.ibm.com>");
MODULE_DESCRIPTION("ECDSA generic algorithm");
MODULE_ALIAS_CRYPTO("ecdsa-generic");
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