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    Subject[PATCH 13/21] PGPLIB: Basic packet parser [ver #3]
    Date
    Provide a simple parser that extracts the packets from a PGP packet blob and
    passes the desirous ones to the given processor function:

    struct pgp_parse_context {
    u64 types_of_interest;
    int (*process_packet)(struct pgp_parse_context *context,
    enum pgp_packet_tag type,
    u8 headerlen,
    const u8 *data,
    size_t datalen);
    };

    int pgp_parse_packets(const u8 *data, size_t datalen,
    struct pgp_parse_context *ctx);

    This is configured on with CONFIG_PGP_LIBRARY.

    Signed-off-by: David Howells <dhowells@redhat.com>
    ---

    include/linux/pgp.h | 25 ++++
    security/keys/Kconfig | 6 +
    security/keys/Makefile | 1
    security/keys/pgp_library.c | 254 +++++++++++++++++++++++++++++++++++++++++++
    4 files changed, 286 insertions(+), 0 deletions(-)
    create mode 100644 security/keys/pgp_library.c


    diff --git a/include/linux/pgp.h b/include/linux/pgp.h
    index 5d4b372..06f5aaa 100644
    --- a/include/linux/pgp.h
    +++ b/include/linux/pgp.h
    @@ -203,4 +203,29 @@ struct pgp_key_v4_packet {
    u8 key_material[0];
    };

    +/*
    + * PGP library packet parser
    + */
    +struct pgp_parse_context {
    + u64 types_of_interest;
    + int (*process_packet)(struct pgp_parse_context *context,
    + enum pgp_packet_tag type,
    + u8 headerlen,
    + const u8 *data,
    + size_t datalen);
    +};
    +
    +extern int pgp_parse_packets(const u8 *data, size_t datalen,
    + struct pgp_parse_context *ctx);
    +
    +struct pgp_parse_pubkey {
    + enum pgp_key_version version : 8;
    + enum pgp_pubkey_algo pubkey_algo : 8;
    + time_t creation_time;
    + time_t expires_at;
    +};
    +
    +extern int pgp_parse_public_key(const u8 **_data, size_t *_datalen,
    + struct pgp_parse_pubkey *pk);
    +
    #endif /* _LINUX_PGP_H */
    diff --git a/security/keys/Kconfig b/security/keys/Kconfig
    index 0090cd5..3196ba8 100644
    --- a/security/keys/Kconfig
    +++ b/security/keys/Kconfig
    @@ -99,3 +99,9 @@ config CRYPTO_KEY_PKEY_ALGO_RSA
    depends on CRYPTO_KEY_PUBLIC_KEY_SUBTYPE
    help
    This option enables support for the RSA algorithm (PKCS#1, RFC3447).
    +
    +config PGP_LIBRARY
    + tristate "PGP parsing library"
    + help
    + This option enables a library that provides a number of simple
    + utility functions for parsing PGP (RFC 4880) packet-based messages.
    diff --git a/security/keys/Makefile b/security/keys/Makefile
    index 7245a20..3c3918a 100644
    --- a/security/keys/Makefile
    +++ b/security/keys/Makefile
    @@ -28,5 +28,6 @@ obj-$(CONFIG_CRYPTO_KEY_TYPE) += crypto_keys.o
    obj-$(CONFIG_CRYPTO_KEY_PUBLIC_KEY_SUBTYPE) += public_key.o
    obj-$(CONFIG_CRYPTO_KEY_PKEY_ALGO_DSA) += crypto_dsa.o
    obj-$(CONFIG_CRYPTO_KEY_PKEY_ALGO_RSA) += crypto_rsa.o
    +obj-$(CONFIG_PGP_LIBRARY) += pgp_library.o

    crypto_keys-y := crypto_type.o crypto_verify.o
    diff --git a/security/keys/pgp_library.c b/security/keys/pgp_library.c
    new file mode 100644
    index 0000000..685660f
    --- /dev/null
    +++ b/security/keys/pgp_library.c
    @@ -0,0 +1,254 @@
    +/* PGP packet parser (RFC 4880)
    + *
    + * Copyright (C) 2011 Red Hat, Inc. All Rights Reserved.
    + * Written by David Howells (dhowells@redhat.com)
    + *
    + * This program is free software; you can redistribute it and/or
    + * modify it under the terms of the GNU General Public Licence
    + * as published by the Free Software Foundation; either version
    + * 2 of the Licence, or (at your option) any later version.
    + */
    +#define pr_fmt(fmt) "PGP: "fmt
    +#include <linux/pgp.h>
    +#include <linux/errno.h>
    +#include <linux/kernel.h>
    +#include <linux/module.h>
    +
    +MODULE_LICENSE("GPL");
    +
    +const char *const pgp_hash_algorithms[PGP_HASH__LAST] = {
    + [PGP_HASH_MD5] = "md5",
    + [PGP_HASH_SHA1] = "sha1",
    + [PGP_HASH_RIPE_MD_160] = "rmd160",
    + [PGP_HASH_SHA256] = "sha256",
    + [PGP_HASH_SHA384] = "sha384",
    + [PGP_HASH_SHA512] = "sha512",
    + [PGP_HASH_SHA224] = "sha224",
    +};
    +EXPORT_SYMBOL_GPL(pgp_hash_algorithms);
    +
    +/**
    + * pgp_parse_packet_header - Parse a PGP packet header
    + * @_data: Start of the PGP packet (updated to PGP packet data)
    + * @_datalen: Amount of data remaining in buffer (decreased)
    + * @_type: Where the packet type will be returned
    + * @_headerlen: Where the header length will be returned
    + *
    + * Parse a set of PGP packet header [RFC 4880: 4.2].
    + *
    + * Returns packet data size on success; non-zero on error. If successful,
    + * *_data and *_datalen will have been updated and *_headerlen will be set to
    + * hold the length of the packet header.
    + */
    +ssize_t pgp_parse_packet_header(const u8 **_data, size_t *_datalen,
    + enum pgp_packet_tag *_type,
    + u8 *_headerlen)
    +{
    + enum pgp_packet_tag type;
    + const u8 *data = *_data;
    + size_t size, datalen = *_datalen;
    +
    + pr_devel("-->pgp_parse_packet_header(,%zu,,)", datalen);
    +
    + if (datalen < 2)
    + goto short_packet;
    +
    + pr_devel("pkthdr %02x, %02x\n", data[0], data[1]);
    +
    + type = *data++;
    + datalen--;
    + if (!(type & 0x80)) {
    + pr_debug("Packet type does not have MSB set\n");
    + return -EBADMSG;
    + }
    + type &= ~0x80;
    +
    + if (type & 0x40) {
    + /* New packet length format */
    + type &= ~0x40;
    + pr_devel("new format: t=%u\n", type);
    + switch (data[0]) {
    + case 0x00 ... 0xbf:
    + /* One-byte length */
    + size = data[0];
    + data++;
    + datalen--;
    + *_headerlen = 2;
    + break;
    + case 0xc0 ... 0xdf:
    + /* Two-byte length */
    + if (datalen < 2)
    + goto short_packet;
    + size = (data[0] - 192) * 256;
    + size += data[1] + 192;
    + data += 2;
    + datalen -= 2;
    + *_headerlen = 3;
    + break;
    + case 0xff:
    + pr_debug("Five-byte packet length not supported\n");
    + return -EBADMSG;
    + default:
    + pr_debug("Error parsing packet length\n");
    + return -EBADMSG;
    + }
    + } else {
    + /* Old packet length format */
    + u8 length_type = type & 0x03;
    + type >>= 2;
    + pr_devel("old format: t=%u lt=%u\n", type, length_type);
    +
    + switch (length_type) {
    + case 0:
    + /* One-byte length */
    + size = data[0];
    + data++;
    + datalen--;
    + *_headerlen = 2;
    + break;
    + case 1:
    + /* Two-byte length */
    + if (datalen < 2)
    + goto short_packet;
    + size = data[0] << 8;
    + size |= data[1];
    + data += 2;
    + datalen -= 2;
    + *_headerlen = 3;
    + break;
    + case 2:
    + /* Four-byte length */
    + if (datalen < 4)
    + goto short_packet;
    + size = data[0] << 24;
    + size |= data[1] << 16;
    + size |= data[2] << 8;
    + size |= data[3];
    + data += 4;
    + datalen -= 4;
    + *_headerlen = 5;
    + break;
    + default:
    + pr_debug("Indefinite length packet not supported\n");
    + return -EBADMSG;
    + }
    + }
    +
    + pr_devel("datalen=%zu size=%zu", datalen, size);
    + if (datalen < size)
    + goto short_packet;
    +
    + *_data = data;
    + *_datalen = datalen;
    + *_type = type;
    + pr_devel("Found packet type=%u size=%zd\n", type, size);
    + return size;
    +
    +short_packet:
    + pr_debug("Attempt to parse short packet\n");
    + return -EBADMSG;
    +}
    +
    +/**
    + * pgp_parse_packets - Parse a set of PGP packets
    + * @_data: Data to be parsed (updated)
    + * @_datalen: Amount of data (updated)
    + * @ctx: Parsing context
    + *
    + * Parse a set of PGP packets [RFC 4880: 4].
    + */
    +int pgp_parse_packets(const u8 *data, size_t datalen,
    + struct pgp_parse_context *ctx)
    +{
    + enum pgp_packet_tag type;
    + ssize_t pktlen;
    + u8 headerlen;
    + int ret;
    +
    + while (datalen > 2) {
    + pktlen = pgp_parse_packet_header(&data, &datalen, &type,
    + &headerlen);
    + if (pktlen < 0)
    + return pktlen;
    +
    + if ((ctx->types_of_interest >> type) & 1) {
    + ret = ctx->process_packet(ctx, type, headerlen,
    + data, pktlen);
    + if (ret < 0)
    + return ret;
    + }
    + data += pktlen;
    + datalen -= pktlen;
    + }
    +
    + if (datalen != 0) {
    + pr_debug("Excess octets in packet stream\n");
    + return -EBADMSG;
    + }
    +
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(pgp_parse_packets);
    +
    +/**
    + * pgp_parse_public_key - Parse the common part of a PGP pubkey packet
    + * @_data: Content of packet (updated)
    + * @_datalen: Length of packet remaining (updated)
    + * @pk: Public key data
    + *
    + * Parse the common data struct for a PGP pubkey packet [RFC 4880: 5.5.2].
    + */
    +int pgp_parse_public_key(const u8 **_data, size_t *_datalen,
    + struct pgp_parse_pubkey *pk)
    +{
    + const u8 *data = *_data;
    + size_t datalen = *_datalen;
    + __be32 tmp;
    +
    + if (datalen < 12) {
    + pr_debug("Public key packet too short\n");
    + return -EBADMSG;
    + }
    +
    + pk->version = *data++;
    + switch (pk->version) {
    + case PGP_KEY_VERSION_2:
    + case PGP_KEY_VERSION_3:
    + case PGP_KEY_VERSION_4:
    + break;
    + default:
    + pr_debug("Public key packet with unhandled version %d\n",
    + pk->version);
    + return -EBADMSG;
    + }
    +
    + tmp = *data++ << 24;
    + tmp |= *data++ << 16;
    + tmp |= *data++ << 8;
    + tmp |= *data++;
    + pk->creation_time = tmp;
    + if (pk->version == PGP_KEY_VERSION_4) {
    + pk->expires_at = 0; /* Have to get it from the selfsignature */
    + } else {
    + unsigned short ndays;
    + ndays = *data++ << 8;
    + ndays |= *data++;
    + if (ndays)
    + pk->expires_at = pk->creation_time + ndays * 86400UL;
    + else
    + pk->expires_at = 0;
    + datalen -= 2;
    + }
    +
    + pk->pubkey_algo = *data++;
    + datalen -= 6;
    +
    + pr_devel("%x,%x,%lx,%lx",
    + pk->version, pk->pubkey_algo, pk->creation_time,
    + pk->expires_at);
    +
    + *_data = data;
    + *_datalen = datalen;
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(pgp_parse_public_key);


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      Last update: 2011-12-02 19:47    [W:0.037 / U:33.924 seconds]
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