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841785bad1
This is a major rewrite of the description of 'crypt', 'getentropy', and 'getrandom'. A few highlights of the content changes: - Throughout the manual, public headers, and user-visible messages, I replaced the term "password" with "passphrase", the term "password database" with "user database", and the term "encrypt(ion)" with "(one-way) hashing" whenever it was applied to passphrases. I didn't bother making this change in internal code or tests. The use of the term "password" in ruserpass.c survives, because that refers to a keyword in netrc files, but it is adjusted to make this clearer. There is a note in crypt.texi explaining that they were traditionally called passwords but single words are not good enough anymore, and a note in users.texi explaining that actual passphrase hashes are found in a "shadow" database nowadays. - There is a new short introduction to the "Cryptographic Functions" section, explaining how we do not intend to be a general-purpose cryptography library, and cautioning that there _are_, or have been, legal restrictions on the use of cryptography in many countries, without getting into any kind of detail that we can't promise to keep up to date. - I added more detail about what a "one-way function" is, and why they are used to obscure passphrases for storage. I removed the paragraph saying that systems not connected to a network need no user authentication, because that's a pretty rare situation nowadays. (It still says "sometimes it is necessary" to authenticate the user, though.) - I added documentation for all of the hash functions that glibc actually supports, but not for the additional hash functions supported by libxcrypt. If we're going to keep this manual section around after the transition is more advanced, it would probably make sense to add them then. - There is much more detailed discussion of how to generate a salt, and the failure behavior for crypt is documented. (Returning an invalid hash on failure is what libxcrypt does; Solar Designer's notes say that this was done "for compatibility with old programs that assume crypt can never fail".) - As far as I can tell, the header 'crypt.h' is entirely a GNU invention, and never existed on any other Unix lineage. The function 'crypt', however, was in Issue 1 of the SVID and is now in the XSI component of POSIX. I tried to make all of the @standards annotations consistent with this, but I'm not sure I got them perfectly right. - The genpass.c example has been improved to use getentropy instead of the current time to generate the salt, and to use a SHA-256 hash instead of MD5. It uses more random bytes than is strictly necessary because I didn't want to complicate the code with proper base64 encoding. - The testpass.c example has three hardwired hashes now, to demonstrate that different one-way functions produce different hashes for the same input. It also demonstrates how DES hashing only pays attention to the first eight characters of the input. - There is new text explaining in more detail how a CSPRNG differs from a regular random number generator, and how getentropy/getrandom are not exactly a CSPRNG. I tried not to make specific falsifiable claims here. I also tried to make the blocking/cancellation/error behavior of both getentropy and getrandom clearer.
251 lines
6.4 KiB
C
251 lines
6.4 KiB
C
/*
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* Copyright (c) 1985, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <ctype.h>
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#include <err.h>
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#include <errno.h>
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#include <netdb.h>
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#include <stdio.h>
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#include <stdio_ext.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <libintl.h>
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/* #include "ftp_var.h" */
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static int token (void);
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static FILE *cfile;
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#define DEFAULT 1
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#define LOGIN 2
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#define PASSWD 3
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#define ACCOUNT 4
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#define MACDEF 5
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#define ID 10
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#define MACHINE 11
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static char tokval[100];
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static const char tokstr[] =
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{
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#define TOK_DEFAULT_IDX 0
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"default\0"
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#define TOK_LOGIN_IDX (TOK_DEFAULT_IDX + sizeof "default")
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"login\0"
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#define TOK_PASSWORD_IDX (TOK_LOGIN_IDX + sizeof "login")
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"password\0"
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#define TOK_PASSWD_IDX (TOK_PASSWORD_IDX + sizeof "password")
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"passwd\0"
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#define TOK_ACCOUNT_IDX (TOK_PASSWD_IDX + sizeof "passwd")
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"account\0"
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#define TOK_MACHINE_IDX (TOK_ACCOUNT_IDX + sizeof "account")
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"machine\0"
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#define TOK_MACDEF_IDX (TOK_MACHINE_IDX + sizeof "machine")
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"macdef"
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};
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static const struct toktab {
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int tokstr_off;
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int tval;
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} toktab[]= {
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{ TOK_DEFAULT_IDX, DEFAULT },
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{ TOK_LOGIN_IDX, LOGIN },
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{ TOK_PASSWORD_IDX, PASSWD },
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{ TOK_PASSWD_IDX, PASSWD },
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{ TOK_ACCOUNT_IDX, ACCOUNT },
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{ TOK_MACHINE_IDX, MACHINE },
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{ TOK_MACDEF_IDX, MACDEF }
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};
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int
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ruserpass (const char *host, const char **aname, const char **apass)
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{
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char *hdir, *buf, *tmp;
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char myname[1024], *mydomain;
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int t, usedefault = 0;
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struct stat64 stb;
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hdir = __libc_secure_getenv("HOME");
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if (hdir == NULL) {
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/* If we can't get HOME, fail instead of trying ".",
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which is no improvement. This really should call
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getpwuid(getuid()). */
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/*hdir = ".";*/
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return -1;
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}
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buf = alloca (strlen (hdir) + 8);
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__stpcpy (__stpcpy (buf, hdir), "/.netrc");
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cfile = fopen(buf, "rce");
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if (cfile == NULL) {
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if (errno != ENOENT)
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warn("%s", buf);
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return (0);
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}
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/* No threads use this stream. */
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__fsetlocking (cfile, FSETLOCKING_BYCALLER);
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if (__gethostname(myname, sizeof(myname)) < 0)
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myname[0] = '\0';
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mydomain = __strchrnul(myname, '.');
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next:
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while ((t = token())) switch(t) {
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case DEFAULT:
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usedefault = 1;
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/* FALL THROUGH */
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case MACHINE:
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if (!usedefault) {
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if (token() != ID)
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continue;
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/*
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* Allow match either for user's input host name
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* or official hostname. Also allow match of
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* incompletely-specified host in local domain.
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*/
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if (__strcasecmp(host, tokval) == 0)
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goto match;
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/* if (__strcasecmp(hostname, tokval) == 0)
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goto match;
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if ((tmp = strchr(hostname, '.')) != NULL &&
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__strcasecmp(tmp, mydomain) == 0 &&
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__strncasecmp(hostname, tokval, tmp-hostname) == 0 &&
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tokval[tmp - hostname] == '\0')
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goto match; */
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if ((tmp = strchr(host, '.')) != NULL &&
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__strcasecmp(tmp, mydomain) == 0 &&
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__strncasecmp(host, tokval, tmp - host) == 0 &&
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tokval[tmp - host] == '\0')
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goto match;
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continue;
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}
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match:
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while ((t = token()) && t != MACHINE && t != DEFAULT) switch(t) {
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case LOGIN:
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if (token()) {
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if (*aname == 0) {
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char *newp;
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newp = malloc((unsigned) strlen(tokval) + 1);
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if (newp == NULL)
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{
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warnx(_("out of memory"));
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goto bad;
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}
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*aname = strcpy(newp, tokval);
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} else {
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if (strcmp(*aname, tokval))
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goto next;
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}
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}
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break;
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case PASSWD:
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if (strcmp(*aname, "anonymous") &&
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fstat64(fileno(cfile), &stb) >= 0 &&
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(stb.st_mode & 077) != 0) {
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warnx(_("Error: .netrc file is readable by others."));
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warnx(_("Remove 'password' line or make file unreadable by others."));
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goto bad;
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}
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if (token() && *apass == 0) {
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char *newp;
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newp = malloc((unsigned) strlen(tokval) + 1);
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if (newp == NULL)
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{
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warnx(_("out of memory"));
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goto bad;
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}
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*apass = strcpy(newp, tokval);
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}
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break;
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case ACCOUNT:
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break;
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case MACDEF:
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break;
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default:
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warnx(_("Unknown .netrc keyword %s"), tokval);
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break;
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}
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goto done;
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}
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done:
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(void) fclose(cfile);
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return (0);
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bad:
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(void) fclose(cfile);
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return (-1);
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}
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libc_hidden_def (ruserpass)
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static int
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token (void)
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{
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char *cp;
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int c;
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int i;
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if (feof_unlocked(cfile) || ferror_unlocked(cfile))
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return (0);
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while ((c = getc_unlocked(cfile)) != EOF &&
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(c == '\n' || c == '\t' || c == ' ' || c == ','))
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continue;
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if (c == EOF)
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return (0);
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cp = tokval;
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if (c == '"') {
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while ((c = getc_unlocked(cfile)) != EOF && c != '"') {
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if (c == '\\')
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c = getc_unlocked(cfile);
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*cp++ = c;
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}
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} else {
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*cp++ = c;
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while ((c = getc_unlocked(cfile)) != EOF
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&& c != '\n' && c != '\t' && c != ' ' && c != ',') {
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if (c == '\\')
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c = getc_unlocked(cfile);
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*cp++ = c;
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}
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}
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*cp = 0;
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if (tokval[0] == 0)
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return (0);
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for (i = 0; i < (int) (sizeof (toktab) / sizeof (toktab[0])); ++i)
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if (!strcmp(&tokstr[toktab[i].tokstr_off], tokval))
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return toktab[i].tval;
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return (ID);
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}
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