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auth_unix.c
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auth_unix.c
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/* auth_unix.c -- Unix passwd file authorization
*
* Copyright (c) 1994-2008 Carnegie Mellon University. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The name "Carnegie Mellon University" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For permission or any legal
* details, please contact
* Carnegie Mellon University
* Center for Technology Transfer and Enterprise Creation
* 4615 Forbes Avenue
* Suite 302
* Pittsburgh, PA 15213
* (412) 268-7393, fax: (412) 268-7395
* innovation@andrew.cmu.edu
*
* 4. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by Computing Services
* at Carnegie Mellon University (http://www.cmu.edu/computing/)."
*
* CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
* FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <config.h>
#include <stdlib.h>
#include <pwd.h>
#include <grp.h>
#include <ctype.h>
#include <string.h>
#include "auth.h"
#include "libcyr_cfg.h"
#include "xmalloc.h"
#include "strarray.h"
#include "util.h"
struct auth_state {
char userid[81];
strarray_t groups;
};
static struct auth_state auth_anonymous = {
"anonymous", STRARRAY_INITIALIZER
};
/*
* Determine if the user is a member of 'identifier'
* Returns one of:
* 0 User does not match identifier
* 1 identifier matches everybody
* 2 User is in the group that is identifier
* 3 User is identifer
*/
static int mymemberof(struct auth_state *auth_state, const char *identifier)
{
int i;
if (!auth_state) auth_state = &auth_anonymous;
if (strcmp(identifier, "anyone") == 0) return 1;
if (strcmp(identifier, auth_state->userid) == 0) return 3;
if (strncmp(identifier, "group:", 6) != 0) return 0;
for (i=0; i<auth_state->groups.count ; i++) {
if (strcmp(identifier+6, auth_state->groups.data[i]) == 0) return 2;
}
return 0;
}
/* Map of which characters are allowed by auth_canonifyid.
* Key: 0 -> not allowed (special, ctrl, or would confuse Unix or imapd)
* 1 -> allowed, but requires an alpha somewhere else in the string
* 2 -> allowed, and is an alpha
*
* At least one character must be an alpha.
*
* This may not be restrictive enough.
* Here are the reasons for the restrictions:
*
* & forbidden because of MUTF-7. (This could be fixed.)
* : forbidden because it's special in /etc/passwd
* / forbidden because it can't be used in a mailbox name
* * % forbidden because they're IMAP magic in the LIST/LSUB commands
* ? it just scares me
* ctrl chars, DEL
* can't send them as IMAP characters in plain folder names, I think
* 80-FF forbidden because you can't send them in IMAP anyway
* (and they're forbidden as folder names). (This could be fixed.)
*
* + and - are *allowed* although '+' is probably used for userid+detail
* subaddressing and qmail users use '-' for subaddressing.
*
* Identifiers don't require a digit, really, so that should probably be
* relaxed, too.
*/
static char allowedchars[256] = {
/* 0 1 2 3 4 5 6 7 8 9 A B C D E F */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 00-0F */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 10-1F */
1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, /* 20-2F */
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, /* 30-3F */
1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, /* 40-4F */
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, /* 50-5F */
1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, /* 60-6F */
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 0, /* 70-7F */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
/*
* Convert 'identifier' into canonical form.
* Returns a pointer to a static buffer containing the canonical form
* or NULL if 'identifier' is invalid.
*
* XXX If any of the characters marked with 0 are valid and are cropping up,
* the right thing to do is probably to canonicalize the identifier to two
* representations: one for getpwent calls and one for folder names. The
* latter canonicalizes to a MUTF7 representation.
*/
static const char *mycanonifyid(const char *identifier, size_t len)
{
static char retbuf[81];
struct group *grp;
char *p;
int username_tolower = 0;
if (!len) len = strlen(identifier);
if (len >= sizeof(retbuf)) return NULL;
memmove(retbuf, identifier, len);
retbuf[len] = '\0';
/* This used to be far more restrictive, but many sites seem to ignore the
* ye olde Unix conventions of username. Specifically, we used to
* - drop case on the buffer
* - disallow lots of non-alpha characters ('-', '_', others)
* Now we do neither of these, but impose a very different policy based on
* the character map above.
*/
if (!strncmp(retbuf, "group:", 6)) {
grp = getgrnam(retbuf+6);
if (!grp) return NULL;
if (strlen(grp->gr_name) >= sizeof(retbuf)-6)
return NULL;
strcpy(retbuf+6, grp->gr_name);
return retbuf;
}
/* Copy the string and look up values in the allowedchars array above.
* If we see any we don't like, reject the string.
* Lowercase usernames if requested.
*/
username_tolower = libcyrus_config_getswitch(CYRUSOPT_USERNAME_TOLOWER);
for (p = retbuf; *p; p++) {
if (username_tolower && Uisupper(*p))
*p = tolower((unsigned char)*p);
switch (allowedchars[*(unsigned char*) p]) {
case 0:
return NULL;
default:
break;
}
}
return retbuf;
}
/*
* Set the current user to 'identifier'. 'cacheid', if non-null,
* points to a 16-byte binary key to cache identifier's information
* with.
*/
static struct auth_state *mynewstate(const char *identifier)
{
struct auth_state *newstate;
struct passwd *pwd;
struct group *grp;
#if defined(HAVE_GETGROUPLIST) && defined(__GLIBC__)
gid_t gid, *groupids = NULL;
int ret, ngroups = 10, oldngroups;
#else
char **mem;
#endif
identifier = mycanonifyid(identifier, 0);
if (!identifier) return 0;
if (!strncmp(identifier, "group:", 6)) return 0;
newstate = (struct auth_state *)xmalloc(sizeof(struct auth_state));
strcpy(newstate->userid, identifier);
strarray_init(&newstate->groups);
if(!libcyrus_config_getswitch(CYRUSOPT_AUTH_UNIX_GROUP_ENABLE))
return newstate;
pwd = getpwnam(identifier);
#if defined(HAVE_GETGROUPLIST) && defined(__GLIBC__)
gid = pwd ? pwd->pw_gid : (gid_t) -1;
/* get the group ids */
do {
groupids = (gid_t *)xrealloc((gid_t *)groupids,
ngroups * sizeof(gid_t));
oldngroups = ngroups; /* copy of ngroups for comparision */
ret = getgrouplist(identifier, gid, groupids, &ngroups);
/*
* This is tricky. We do this as long as getgrouplist tells us to
* realloc _and_ the number of groups changes. It tells us to realloc
* also in the case of failure...
*/
} while (ret == -1 && ngroups != oldngroups);
if (ret == -1)
goto err;
while (ngroups--) {
if (pwd || groupids[ngroups] != gid) {
if ((grp = getgrgid(groupids[ngroups])))
strarray_append(&newstate->groups, grp->gr_name);
}
}
err:
if (groupids) free(groupids);
#else /* !HAVE_GETGROUPLIST */
setgrent();
while ((grp = getgrent())) {
for (mem = grp->gr_mem; *mem; mem++) {
if (!strcmp(*mem, identifier)) break;
}
if (*mem || (pwd && pwd->pw_gid == grp->gr_gid))
strarray_append(&newstate->groups, grp->gr_name);
}
endgrent();
#endif /* HAVE_GETGROUPLIST */
return newstate;
}
static void myfreestate(struct auth_state *auth_state)
{
strarray_fini(&auth_state->groups);
free(auth_state);
}
HIDDEN struct auth_mech auth_unix =
{
"unix", /* name */
&mycanonifyid,
&mymemberof,
&mynewstate,
&myfreestate,
};

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