-/*
- * Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>
- *
- * Licensed under the GPL v2. For licencing details see COPYING.
- */
+/* Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
/** \file crypt_common.c Crypto functions independent of openssl/libgcrypt. */
#include "string.h"
#include "crypt.h"
#include "crypt_backend.h"
+#include "portable_io.h"
+#include "fd.h"
+#include "base64.h"
/** If the key begins with this text, we treat it as an ssh key. */
#define KEY_TYPE_TXT "ssh-rsa"
-/**
- * Check if given buffer starts with a ssh rsa key signature.
- *
- * \param data The buffer.
- * \param size Number of data bytes.
+/*
+ * Check if the given buffer starts with an ssh rsa key signature.
*
- * \return Number of header bytes to be skipped on success, zero if
- * ssh rsa signature was not found.
+ * Returns number of header bytes to be skipped on success, zero if no ssh rsa
+ * signature was found.
*/
-size_t is_ssh_rsa_key(char *data, size_t size)
+static size_t is_ssh_rsa_key(char *data, size_t size)
{
char *cp;
return cp - data;
}
-/**
- * Read a 4-byte number from a buffer in big-endian format.
- *
- * \param vp The buffer.
- *
- * The byte-order of the buffer is expected to be big-endian, unlike read_u32()
- * of portable_io.h which expects little endian.
- *
- * \return The 32 bit number given by \a vp.
- */
-uint32_t read_ssh_u32(const void *vp)
-{
- const unsigned char *p = (const unsigned char *)vp;
- uint32_t v;
-
- v = (uint32_t)p[0] << 24;
- v |= (uint32_t)p[1] << 16;
- v |= (uint32_t)p[2] << 8;
- v |= (uint32_t)p[3];
-
- return v;
-}
-
-/**
- * Sanity checks for the header of an ssh key.
- *
- * \param blob The buffer.
- * \param blen The number of bytes of \a blob.
- *
- * This performs some checks to make sure we really have an ssh key. It also
- * computes the offset in bytes of the start of the key values (modulus,
- * exponent..).
+/*
+ * Perform some sanity checks on the decoded ssh key.
*
- * \return The number of bytes to skip until the start of the first encoded
- * number (usually 11).
+ * This function returns the size of the header. Usually, the header is 11
+ * bytes long: four bytes for the length field, and the string "ssh-rsa".
*/
-int check_ssh_key_header(const unsigned char *blob, int blen)
+static int check_ssh_key_header(const unsigned char *blob, int blen)
{
const unsigned char *p = blob, *end = blob + blen;
uint32_t rlen;
if (p + 4 > end)
return -E_SSH_KEY_HEADER;
- rlen = read_ssh_u32(p);
+ rlen = read_u32_be(p);
p += 4;
if (p + rlen < p)
return -E_SSH_KEY_HEADER;
return 4 + rlen;
}
+/**
+ * Perform sanity checks and base64-decode an ssh-rsa key.
+ *
+ * \param filename The public key file (usually id_rsa.pub).
+ * \param blob Pointer to base64-decoded blob is returned here.
+ * \param decoded_size The size of the decoded blob.
+ *
+ * The memory pointed at by the returned blob pointer has to be freed by the
+ * caller.
+ *
+ * \return On success, the offset in bytes of the start of the key values
+ * (modulus, exponent..). This is the number of bytes to skip from the blob
+ * until the start of the first encoded number. On failure, a negative error
+ * code is returned.
+ *
+ * \sa \ref uudecode().
+ */
+int decode_public_key(const char *filename, unsigned char **blob,
+ size_t *decoded_size)
+{
+ int ret, ret2;
+ void *map;
+ size_t map_size;
+
+ ret = mmap_full_file(filename, O_RDONLY, &map, &map_size, NULL);
+ if (ret < 0)
+ return ret;
+ ret = is_ssh_rsa_key(map, map_size);
+ if (ret == 0) {
+ ret = -E_SSH_PARSE;
+ goto unmap;
+ }
+ ret = uudecode(map + ret, map_size - ret, (char **)blob, decoded_size);
+ if (ret < 0)
+ goto unmap;
+ ret = check_ssh_key_header(*blob, *decoded_size);
+ if (ret < 0)
+ goto unmap;
+unmap:
+ ret2 = para_munmap(map, map_size);
+ if (ret >= 0 && ret2 < 0)
+ ret = ret2;
+ return ret;
+}
+
/**
* Check existence and permissions of a private key file.
*
return 1;
}
-void hash_to_asc(unsigned char *hash, char *asc)
+void hash_to_asc(const unsigned char *hash, char *asc)
{
int i;
const char hexchar[] = "0123456789abcdef";
asc[2 * HASH_SIZE] = '\0';
}
-int hash_compare(unsigned char *h1, unsigned char *h2)
+int hash_compare(const unsigned char *h1, const unsigned char *h2)
{
int i;
}
return 0;
}
+
+void hash2_to_asc(const unsigned char *hash, char *asc)
+{
+ int i;
+ const char hexchar[] = "0123456789abcdef";
+
+ for (i = 0; i < HASH2_SIZE; i++) {
+ asc[2 * i] = hexchar[hash[i] >> 4];
+ asc[2 * i + 1] = hexchar[hash[i] & 0xf];
+ }
+ asc[2 * HASH2_SIZE] = '\0';
+}
+
+int hash2_compare(const unsigned char *h1, const unsigned char *h2)
+{
+ int i;
+
+ for (i = 0; i < HASH2_SIZE; i++) {
+ if (h1[i] < h2[i])
+ return -1;
+ if (h1[i] > h2[i])
+ return 1;
+ }
+ return 0;
+}
+
+/**
+ * Check header of an openssh private key and compute bignum offset.
+ *
+ * \param data The base64-decoded key.
+ * \param len The size of the decoded key.
+ *
+ * Several assumptions are made about the key. Most notably, we only support
+ * single unencrypted keys without comments.
+ *
+ * \return The offset at which the first bignum of the private key (the public
+ * exponent n) starts. Negative error code on failure.
+ */
+int find_openssh_bignum_offset(const unsigned char *data, int len)
+{
+ /*
+ * Unencrypted keys without comments always start with the below byte
+ * sequence. See PROTOCOL.key of the openssh package.
+ */
+ static const unsigned char valid_openssh_header[] = {
+ /* string "openssh-key-v1" */
+ 0x6f, 0x70, 0x65, 0x6e, 0x73, 0x73, 0x68, 0x2d, 0x6b, 0x65,
+ 0x79, 0x2d, 0x76, 0x31,
+ /* length of the cipher name */
+ 0x00, 0x00, 0x00, 0x00, 0x04,
+ /* cipher name: "none" */
+ 0x6e, 0x6f, 0x6e, 0x65,
+ /* length of the kdfname (only used for encrypted keys) */
+ 0x00, 0x00, 0x00, 0x04,
+ /* kdfname: "none" */
+ 0x6e, 0x6f, 0x6e, 0x65,
+ /* length of kdfoptions */
+ 0x00, 0x00, 0x00, 0x00,
+ /* number of keys */
+ 0x00, 0x00, 0x00, 0x01,
+ };
+ uint32_t val;
+ const unsigned char *p, *end = data + len;
+
+ if (len <= sizeof(valid_openssh_header) + 4)
+ return -E_OPENSSH_PARSE;
+ if (memcmp(data, valid_openssh_header, sizeof(valid_openssh_header)))
+ return -E_OPENSSH_PARSE;
+ p = data + sizeof(valid_openssh_header);
+ /* length of public key */
+ val = read_u32_be(p);
+ if (val > end - p - 4)
+ return -E_OPENSSH_PARSE;
+ p += val + 4;
+ /* length of private key */
+ val = read_u32_be(p);
+ if (val > end - p - 4)
+ return -E_OPENSSH_PARSE;
+ p += 4;
+ /* two equal random integers ("checkint") */
+ if (p + 8 > end)
+ return -E_OPENSSH_PARSE;
+ if (read_u32_be(p) != read_u32_be(p + 4))
+ return -E_OPENSSH_PARSE;
+ p += 8;
+ /* length of name of key type "ssh-rsa" */
+ if (p + 11 > end)
+ return -E_OPENSSH_PARSE;
+ if (read_u32_be(p) != 7)
+ return -E_OPENSSH_PARSE;
+ if (memcmp(p + 4, "ssh-rsa", 7))
+ return -E_OPENSSH_PARSE;
+ p += 11;
+ return p - data;
+}
+
+/** Private PEM keys (legacy format) start with this header. */
+#define PRIVATE_PEM_KEY_HEADER "-----BEGIN RSA PRIVATE KEY-----"
+/** Private OPENSSH keys (RFC4716) start with this header. */
+#define PRIVATE_OPENSSH_KEY_HEADER "-----BEGIN OPENSSH PRIVATE KEY-----"
+/** Private PEM keys (legacy format) end with this footer. */
+#define PRIVATE_PEM_KEY_FOOTER "-----END RSA PRIVATE KEY-----"
+/** Private OPENSSH keys (RFC4716) end with this footer. */
+#define PRIVATE_OPENSSH_KEY_FOOTER "-----END OPENSSH PRIVATE KEY-----"
+
+/**
+ * Decode an openssh-v1 (aka RFC4716) or PEM (aka ASN.1) private key.
+ *
+ * \param key_file The private key file (usually id_rsa).
+ * \param result Pointer to base64-decoded blob is returned here.
+ * \param blob_size The size of the decoded blob.
+ *
+ * This only checks header and footer and base64-decodes the part in between.
+ * No attempt to read the decoded part is made.
+ *
+ * \return Negative on errors, PKT_PEM or PKT_OPENSSH on success, indicating
+ * the type of key.
+ */
+int decode_private_key(const char *key_file, unsigned char **result,
+ size_t *blob_size)
+{
+ int ret, ret2, i, j, key_type;
+ void *map;
+ size_t map_size, key_size;
+ unsigned char *blob = NULL;
+ char *begin, *footer, *key;
+
+ ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
+ if (ret < 0)
+ goto out;
+ ret = -E_KEY_MARKER;
+ if (strncmp(map, PRIVATE_PEM_KEY_HEADER,
+ strlen(PRIVATE_PEM_KEY_HEADER)) == 0) {
+ key_type = PKT_PEM;
+ begin = map + strlen(PRIVATE_PEM_KEY_HEADER);
+ footer = strstr(map, PRIVATE_PEM_KEY_FOOTER);
+ PARA_INFO_LOG("detected legacy PEM key %s\n", key_file);
+ } else if (strncmp(map, PRIVATE_OPENSSH_KEY_HEADER,
+ strlen(PRIVATE_OPENSSH_KEY_HEADER)) == 0) {
+ key_type = PKT_OPENSSH;
+ begin = map + strlen(PRIVATE_OPENSSH_KEY_HEADER);
+ footer = strstr(map, PRIVATE_OPENSSH_KEY_FOOTER);
+ PARA_INFO_LOG("detected openssh key %s\n", key_file);
+ } else
+ goto unmap;
+ if (!footer)
+ goto unmap;
+ /* skip whitespace at the beginning */
+ for (; begin < footer; begin++) {
+ if (para_isspace(*begin))
+ continue;
+ break;
+ }
+ ret = -E_KEY_MARKER;
+ if (begin >= footer)
+ goto unmap;
+
+ key_size = footer - begin;
+ key = para_malloc(key_size + 1);
+ for (i = 0, j = 0; begin + i < footer; i++) {
+ if (para_isspace(begin[i]))
+ continue;
+ key[j++] = begin[i];
+ }
+ key[j] = '\0';
+ ret = base64_decode(key, j, (char **)&blob, blob_size);
+ free(key);
+ if (ret < 0)
+ goto unmap;
+ ret = key_type;
+unmap:
+ ret2 = para_munmap(map, map_size);
+ if (ret >= 0 && ret2 < 0)
+ ret = ret2;
+ if (ret < 0) {
+ free(blob);
+ blob = NULL;
+ }
+out:
+ *result = blob;
+ return ret;
+}
+