X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=crypt_common.c;h=235b8b8d3e398551fc28bfbc746349c5dc8f6f1c;hp=1fd8189ca3c5a201bd2d227bb366bd800757a5a5;hb=3622134825eb94882a8e99acc0ee1889fc0169d6;hpb=40b1bbc50682effec5cf18b0923cfab24e154245 diff --git a/crypt_common.c b/crypt_common.c index 1fd8189c..235b8b8d 100644 --- a/crypt_common.c +++ b/crypt_common.c @@ -1,8 +1,4 @@ -/* - * Copyright (C) 2005 Andre Noll - * - * Licensed under the GPL v2. For licencing details see COPYING. - */ +/* Copyright (C) 2005 Andre Noll , see file COPYING. */ /** \file crypt_common.c Crypto functions independent of openssl/libgcrypt. */ @@ -13,20 +9,20 @@ #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; @@ -45,50 +41,20 @@ size_t is_ssh_rsa_key(char *data, size_t size) 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; @@ -102,6 +68,51 @@ int check_ssh_key_header(const unsigned char *blob, int blen) 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_ssh_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. *