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-rw-r--r--include/linux/asn1_encoder.h32
-rw-r--r--lib/Kconfig3
-rw-r--r--lib/Makefile1
-rw-r--r--lib/asn1_encoder.c454
4 files changed, 490 insertions, 0 deletions
diff --git a/include/linux/asn1_encoder.h b/include/linux/asn1_encoder.h
new file mode 100644
index 000000000000..08cd0c2ad34f
--- /dev/null
+++ b/include/linux/asn1_encoder.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef _LINUX_ASN1_ENCODER_H
+#define _LINUX_ASN1_ENCODER_H
+
+#include <linux/types.h>
+#include <linux/asn1.h>
+#include <linux/asn1_ber_bytecode.h>
+#include <linux/bug.h>
+
+#define asn1_oid_len(oid) (sizeof(oid)/sizeof(u32))
+unsigned char *
+asn1_encode_integer(unsigned char *data, const unsigned char *end_data,
+ s64 integer);
+unsigned char *
+asn1_encode_oid(unsigned char *data, const unsigned char *end_data,
+ u32 oid[], int oid_len);
+unsigned char *
+asn1_encode_tag(unsigned char *data, const unsigned char *end_data,
+ u32 tag, const unsigned char *string, int len);
+unsigned char *
+asn1_encode_octet_string(unsigned char *data,
+ const unsigned char *end_data,
+ const unsigned char *string, u32 len);
+unsigned char *
+asn1_encode_sequence(unsigned char *data, const unsigned char *end_data,
+ const unsigned char *seq, int len);
+unsigned char *
+asn1_encode_boolean(unsigned char *data, const unsigned char *end_data,
+ bool val);
+
+#endif
diff --git a/lib/Kconfig b/lib/Kconfig
index a38cc61256f1..ac3b30697b2b 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -701,3 +701,6 @@ config GENERIC_LIB_DEVMEM_IS_ALLOWED
config PLDMFW
bool
default n
+
+config ASN1_ENCODER
+ tristate
diff --git a/lib/Makefile b/lib/Makefile
index b5307d3eec1a..e11cfc18b6c0 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -280,6 +280,7 @@ obj-$(CONFIG_INTERVAL_TREE_TEST) += interval_tree_test.o
obj-$(CONFIG_PERCPU_TEST) += percpu_test.o
obj-$(CONFIG_ASN1) += asn1_decoder.o
+obj-$(CONFIG_ASN1_ENCODER) += asn1_encoder.o
obj-$(CONFIG_FONT_SUPPORT) += fonts/
diff --git a/lib/asn1_encoder.c b/lib/asn1_encoder.c
new file mode 100644
index 000000000000..41e71aae3ef6
--- /dev/null
+++ b/lib/asn1_encoder.c
@@ -0,0 +1,454 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Simple encoder primitives for ASN.1 BER/DER/CER
+ *
+ * Copyright (C) 2019 James.Bottomley@HansenPartnership.com
+ */
+
+#include <linux/asn1_encoder.h>
+#include <linux/bug.h>
+#include <linux/string.h>
+#include <linux/module.h>
+
+/**
+ * asn1_encode_integer() - encode positive integer to ASN.1
+ * @data: pointer to the pointer to the data
+ * @end_data: end of data pointer, points one beyond last usable byte in @data
+ * @integer: integer to be encoded
+ *
+ * This is a simplified encoder: it only currently does
+ * positive integers, but it should be simple enough to add the
+ * negative case if a use comes along.
+ */
+unsigned char *
+asn1_encode_integer(unsigned char *data, const unsigned char *end_data,
+ s64 integer)
+{
+ int data_len = end_data - data;
+ unsigned char *d = &data[2];
+ bool found = false;
+ int i;
+
+ if (WARN(integer < 0,
+ "BUG: integer encode only supports positive integers"))
+ return ERR_PTR(-EINVAL);
+
+ if (IS_ERR(data))
+ return data;
+
+ /* need at least 3 bytes for tag, length and integer encoding */
+ if (data_len < 3)
+ return ERR_PTR(-EINVAL);
+
+ /* remaining length where at d (the start of the integer encoding) */
+ data_len -= 2;
+
+ data[0] = _tag(UNIV, PRIM, INT);
+ if (integer == 0) {
+ *d++ = 0;
+ goto out;
+ }
+
+ for (i = sizeof(integer); i > 0 ; i--) {
+ int byte = integer >> (8 * (i - 1));
+
+ if (!found && byte == 0)
+ continue;
+
+ /*
+ * for a positive number the first byte must have bit
+ * 7 clear in two's complement (otherwise it's a
+ * negative number) so prepend a leading zero if
+ * that's not the case
+ */
+ if (!found && (byte & 0x80)) {
+ /*
+ * no check needed here, we already know we
+ * have len >= 1
+ */
+ *d++ = 0;
+ data_len--;
+ }
+
+ found = true;
+ if (data_len == 0)
+ return ERR_PTR(-EINVAL);
+
+ *d++ = byte;
+ data_len--;
+ }
+
+ out:
+ data[1] = d - data - 2;
+
+ return d;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_integer);
+
+/* calculate the base 128 digit values setting the top bit of the first octet */
+static int asn1_encode_oid_digit(unsigned char **_data, int *data_len, u32 oid)
+{
+ unsigned char *data = *_data;
+ int start = 7 + 7 + 7 + 7;
+ int ret = 0;
+
+ if (*data_len < 1)
+ return -EINVAL;
+
+ /* quick case */
+ if (oid == 0) {
+ *data++ = 0x80;
+ (*data_len)--;
+ goto out;
+ }
+
+ while (oid >> start == 0)
+ start -= 7;
+
+ while (start > 0 && *data_len > 0) {
+ u8 byte;
+
+ byte = oid >> start;
+ oid = oid - (byte << start);
+ start -= 7;
+ byte |= 0x80;
+ *data++ = byte;
+ (*data_len)--;
+ }
+
+ if (*data_len > 0) {
+ *data++ = oid;
+ (*data_len)--;
+ } else {
+ ret = -EINVAL;
+ }
+
+ out:
+ *_data = data;
+ return ret;
+}
+
+/**
+ * asn1_encode_oid() - encode an oid to ASN.1
+ * @data: position to begin encoding at
+ * @end_data: end of data pointer, points one beyond last usable byte in @data
+ * @oid: array of oids
+ * @oid_len: length of oid array
+ *
+ * this encodes an OID up to ASN.1 when presented as an array of OID values
+ */
+unsigned char *
+asn1_encode_oid(unsigned char *data, const unsigned char *end_data,
+ u32 oid[], int oid_len)
+{
+ int data_len = end_data - data;
+ unsigned char *d = data + 2;
+ int i, ret;
+
+ if (WARN(oid_len < 2, "OID must have at least two elements"))
+ return ERR_PTR(-EINVAL);
+
+ if (WARN(oid_len > 32, "OID is too large"))
+ return ERR_PTR(-EINVAL);
+
+ if (IS_ERR(data))
+ return data;
+
+
+ /* need at least 3 bytes for tag, length and OID encoding */
+ if (data_len < 3)
+ return ERR_PTR(-EINVAL);
+
+ data[0] = _tag(UNIV, PRIM, OID);
+ *d++ = oid[0] * 40 + oid[1];
+
+ data_len -= 3;
+
+ ret = 0;
+
+ for (i = 2; i < oid_len; i++) {
+ ret = asn1_encode_oid_digit(&d, &data_len, oid[i]);
+ if (ret < 0)
+ return ERR_PTR(ret);
+ }
+
+ data[1] = d - data - 2;
+
+ return d;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_oid);
+
+/**
+ * asn1_encode_length() - encode a length to follow an ASN.1 tag
+ * @data: pointer to encode at
+ * @data_len: pointer to remaning length (adjusted by routine)
+ * @len: length to encode
+ *
+ * This routine can encode lengths up to 65535 using the ASN.1 rules.
+ * It will accept a negative length and place a zero length tag
+ * instead (to keep the ASN.1 valid). This convention allows other
+ * encoder primitives to accept negative lengths as singalling the
+ * sequence will be re-encoded when the length is known.
+ */
+static int asn1_encode_length(unsigned char **data, int *data_len, int len)
+{
+ if (*data_len < 1)
+ return -EINVAL;
+
+ if (len < 0) {
+ *((*data)++) = 0;
+ (*data_len)--;
+ return 0;
+ }
+
+ if (len <= 0x7f) {
+ *((*data)++) = len;
+ (*data_len)--;
+ return 0;
+ }
+
+ if (*data_len < 2)
+ return -EINVAL;
+
+ if (len <= 0xff) {
+ *((*data)++) = 0x81;
+ *((*data)++) = len & 0xff;
+ *data_len -= 2;
+ return 0;
+ }
+
+ if (*data_len < 3)
+ return -EINVAL;
+
+ if (len <= 0xffff) {
+ *((*data)++) = 0x82;
+ *((*data)++) = (len >> 8) & 0xff;
+ *((*data)++) = len & 0xff;
+ *data_len -= 3;
+ return 0;
+ }
+
+ if (WARN(len > 0xffffff, "ASN.1 length can't be > 0xffffff"))
+ return -EINVAL;
+
+ if (*data_len < 4)
+ return -EINVAL;
+ *((*data)++) = 0x83;
+ *((*data)++) = (len >> 16) & 0xff;
+ *((*data)++) = (len >> 8) & 0xff;
+ *((*data)++) = len & 0xff;
+ *data_len -= 4;
+
+ return 0;
+}
+
+/**
+ * asn1_encode_tag() - add a tag for optional or explicit value
+ * @data: pointer to place tag at
+ * @end_data: end of data pointer, points one beyond last usable byte in @data
+ * @tag: tag to be placed
+ * @string: the data to be tagged
+ * @len: the length of the data to be tagged
+ *
+ * Note this currently only handles short form tags < 31.
+ *
+ * Standard usage is to pass in a @tag, @string and @length and the
+ * @string will be ASN.1 encoded with @tag and placed into @data. If
+ * the encoding would put data past @end_data then an error is
+ * returned, otherwise a pointer to a position one beyond the encoding
+ * is returned.
+ *
+ * To encode in place pass a NULL @string and -1 for @len and the
+ * maximum allowable beginning and end of the data; all this will do
+ * is add the current maximum length and update the data pointer to
+ * the place where the tag contents should be placed is returned. The
+ * data should be copied in by the calling routine which should then
+ * repeat the prior statement but now with the known length. In order
+ * to avoid having to keep both before and after pointers, the repeat
+ * expects to be called with @data pointing to where the first encode
+ * returned it and still NULL for @string but the real length in @len.
+ */
+unsigned char *
+asn1_encode_tag(unsigned char *data, const unsigned char *end_data,
+ u32 tag, const unsigned char *string, int len)
+{
+ int data_len = end_data - data;
+ int ret;
+
+ if (WARN(tag > 30, "ASN.1 tag can't be > 30"))
+ return ERR_PTR(-EINVAL);
+
+ if (!string && WARN(len > 127,
+ "BUG: recode tag is too big (>127)"))
+ return ERR_PTR(-EINVAL);
+
+ if (IS_ERR(data))
+ return data;
+
+ if (!string && len > 0) {
+ /*
+ * we're recoding, so move back to the start of the
+ * tag and install a dummy length because the real
+ * data_len should be NULL
+ */
+ data -= 2;
+ data_len = 2;
+ }
+
+ if (data_len < 2)
+ return ERR_PTR(-EINVAL);
+
+ *(data++) = _tagn(CONT, CONS, tag);
+ data_len--;
+ ret = asn1_encode_length(&data, &data_len, len);
+ if (ret < 0)
+ return ERR_PTR(ret);
+
+ if (!string)
+ return data;
+
+ if (data_len < len)
+ return ERR_PTR(-EINVAL);
+
+ memcpy(data, string, len);
+ data += len;
+
+ return data;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_tag);
+
+/**
+ * asn1_encode_octet_string() - encode an ASN.1 OCTET STRING
+ * @data: pointer to encode at
+ * @end_data: end of data pointer, points one beyond last usable byte in @data
+ * @string: string to be encoded
+ * @len: length of string
+ *
+ * Note ASN.1 octet strings may contain zeros, so the length is obligatory.
+ */
+unsigned char *
+asn1_encode_octet_string(unsigned char *data,
+ const unsigned char *end_data,
+ const unsigned char *string, u32 len)
+{
+ int data_len = end_data - data;
+ int ret;
+
+ if (IS_ERR(data))
+ return data;
+
+ /* need minimum of 2 bytes for tag and length of zero length string */
+ if (data_len < 2)
+ return ERR_PTR(-EINVAL);
+
+ *(data++) = _tag(UNIV, PRIM, OTS);
+ data_len--;
+
+ ret = asn1_encode_length(&data, &data_len, len);
+ if (ret)
+ return ERR_PTR(ret);
+
+ if (data_len < len)
+ return ERR_PTR(-EINVAL);
+
+ memcpy(data, string, len);
+ data += len;
+
+ return data;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_octet_string);
+
+/**
+ * asn1_encode_sequence() - wrap a byte stream in an ASN.1 SEQUENCE
+ * @data: pointer to encode at
+ * @end_data: end of data pointer, points one beyond last usable byte in @data
+ * @seq: data to be encoded as a sequence
+ * @len: length of the data to be encoded as a sequence
+ *
+ * Fill in a sequence. To encode in place, pass NULL for @seq and -1
+ * for @len; then call again once the length is known (still with NULL
+ * for @seq). In order to avoid having to keep both before and after
+ * pointers, the repeat expects to be called with @data pointing to
+ * where the first encode placed it.
+ */
+unsigned char *
+asn1_encode_sequence(unsigned char *data, const unsigned char *end_data,
+ const unsigned char *seq, int len)
+{
+ int data_len = end_data - data;
+ int ret;
+
+ if (!seq && WARN(len > 127,
+ "BUG: recode sequence is too big (>127)"))
+ return ERR_PTR(-EINVAL);
+
+ if (IS_ERR(data))
+ return data;
+
+ if (!seq && len >= 0) {
+ /*
+ * we're recoding, so move back to the start of the
+ * sequence and install a dummy length because the
+ * real length should be NULL
+ */
+ data -= 2;
+ data_len = 2;
+ }
+
+ if (data_len < 2)
+ return ERR_PTR(-EINVAL);
+
+ *(data++) = _tag(UNIV, CONS, SEQ);
+ data_len--;
+
+ ret = asn1_encode_length(&data, &data_len, len);
+ if (ret)
+ return ERR_PTR(ret);
+
+ if (!seq)
+ return data;
+
+ if (data_len < len)
+ return ERR_PTR(-EINVAL);
+
+ memcpy(data, seq, len);
+ data += len;
+
+ return data;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_sequence);
+
+/**
+ * asn1_encode_boolean() - encode a boolean value to ASN.1
+ * @data: pointer to encode at
+ * @end_data: end of data pointer, points one beyond last usable byte in @data
+ * @val: the boolean true/false value
+ */
+unsigned char *
+asn1_encode_boolean(unsigned char *data, const unsigned char *end_data,
+ bool val)
+{
+ int data_len = end_data - data;
+
+ if (IS_ERR(data))
+ return data;
+
+ /* booleans are 3 bytes: tag, length == 1 and value == 0 or 1 */
+ if (data_len < 3)
+ return ERR_PTR(-EINVAL);
+
+ *(data++) = _tag(UNIV, PRIM, BOOL);
+ data_len--;
+
+ asn1_encode_length(&data, &data_len, 1);
+
+ if (val)
+ *(data++) = 1;
+ else
+ *(data++) = 0;
+
+ return data;
+}
+EXPORT_SYMBOL_GPL(asn1_encode_boolean);
+
+MODULE_LICENSE("GPL");