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Import pwcache module from OpenBSD
This commit is contained in:
Guillem Jover
437
src/pwcache.c
Normal file
437
src/pwcache.c
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@@ -0,0 +1,437 @@
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/* $OpenBSD: pwcache.c,v 1.15 2018/09/22 02:47:23 millert Exp $ */
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/*-
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* Copyright (c) 1992 Keith Muller.
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* Copyright (c) 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Keith Muller of the University of California, San Diego.
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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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* 3. 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 <assert.h>
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#include <grp.h>
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#include <pwd.h>
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#include <stdio.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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/*
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* Constants and data structures used to implement group and password file
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* caches. Name lengths have been chosen to be as large as those supported
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* by the passwd and group files as well as the standard archive formats.
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* CACHE SIZES MUST BE PRIME
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*/
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#define UNMLEN 32 /* >= user name found in any protocol */
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#define GNMLEN 32 /* >= group name found in any protocol */
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#define UID_SZ 317 /* size of uid to user_name cache */
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#define UNM_SZ 317 /* size of user_name to uid cache */
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#define GID_SZ 251 /* size of gid to group_name cache */
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#define GNM_SZ 251 /* size of group_name to gid cache */
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#define VALID 1 /* entry and name are valid */
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#define INVALID 2 /* entry valid, name NOT valid */
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/*
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* Node structures used in the user, group, uid, and gid caches.
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*/
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typedef struct uidc {
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int valid; /* is this a valid or a miss entry */
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char name[UNMLEN]; /* uid name */
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uid_t uid; /* cached uid */
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} UIDC;
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typedef struct gidc {
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int valid; /* is this a valid or a miss entry */
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char name[GNMLEN]; /* gid name */
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gid_t gid; /* cached gid */
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} GIDC;
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/*
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* Routines that control user, group, uid and gid caches.
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* Traditional passwd/group cache routines perform quite poorly with
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* archives. The chances of hitting a valid lookup with an archive is quite a
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* bit worse than with files already resident on the file system. These misses
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* create a MAJOR performance cost. To adress this problem, these routines
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* cache both hits and misses.
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*/
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static UIDC **uidtb; /* uid to name cache */
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static GIDC **gidtb; /* gid to name cache */
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static UIDC **usrtb; /* user name to uid cache */
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static GIDC **grptb; /* group name to gid cache */
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static u_int
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st_hash(const char *name, size_t len, int tabsz)
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{
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u_int key = 0;
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assert(name != NULL);
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while (len--) {
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key += *name++;
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key = (key << 8) | (key >> 24);
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}
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return key % tabsz;
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}
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/*
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* uidtb_start
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* creates an an empty uidtb
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* Return:
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* 0 if ok, -1 otherwise
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*/
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static int
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uidtb_start(void)
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{
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static int fail = 0;
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if (uidtb != NULL)
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return 0;
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if (fail)
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return -1;
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if ((uidtb = calloc(UID_SZ, sizeof(UIDC *))) == NULL) {
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++fail;
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return -1;
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}
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return 0;
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}
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/*
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* gidtb_start
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* creates an an empty gidtb
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* Return:
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* 0 if ok, -1 otherwise
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*/
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static int
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gidtb_start(void)
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{
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static int fail = 0;
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if (gidtb != NULL)
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return 0;
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if (fail)
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return -1;
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if ((gidtb = calloc(GID_SZ, sizeof(GIDC *))) == NULL) {
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++fail;
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return -1;
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}
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return 0;
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}
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/*
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* usrtb_start
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* creates an an empty usrtb
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* Return:
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* 0 if ok, -1 otherwise
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*/
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static int
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usrtb_start(void)
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{
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static int fail = 0;
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if (usrtb != NULL)
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return 0;
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if (fail)
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return -1;
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if ((usrtb = calloc(UNM_SZ, sizeof(UIDC *))) == NULL) {
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++fail;
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return -1;
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}
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return 0;
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}
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/*
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* grptb_start
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* creates an an empty grptb
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* Return:
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* 0 if ok, -1 otherwise
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*/
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static int
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grptb_start(void)
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{
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static int fail = 0;
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if (grptb != NULL)
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return 0;
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if (fail)
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return -1;
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if ((grptb = calloc(GNM_SZ, sizeof(GIDC *))) == NULL) {
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++fail;
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return -1;
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}
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return 0;
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}
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/*
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* user_from_uid()
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* caches the name (if any) for the uid. If noname clear, we always
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* return the stored name (if valid or invalid match).
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* We use a simple hash table.
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* Return:
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* Pointer to stored name (or a empty string)
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*/
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const char *
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user_from_uid(uid_t uid, int noname)
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{
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struct passwd pwstore, *pw = NULL;
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char pwbuf[_PW_BUF_LEN];
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UIDC **pptr, *ptr = NULL;
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if ((uidtb != NULL) || (uidtb_start() == 0)) {
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/*
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* see if we have this uid cached
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*/
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pptr = uidtb + (uid % UID_SZ);
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ptr = *pptr;
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if ((ptr != NULL) && (ptr->valid > 0) && (ptr->uid == uid)) {
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/*
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* have an entry for this uid
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*/
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if (!noname || (ptr->valid == VALID))
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return ptr->name;
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return NULL;
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}
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if (ptr == NULL)
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*pptr = ptr = malloc(sizeof(UIDC));
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}
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getpwuid_r(uid, &pwstore, pwbuf, sizeof(pwbuf), &pw);
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if (pw == NULL) {
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/*
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* no match for this uid in the local password file
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* a string that is the uid in numeric format
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*/
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if (ptr == NULL)
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return NULL;
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ptr->uid = uid;
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(void)snprintf(ptr->name, UNMLEN, "%u", uid);
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ptr->valid = INVALID;
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if (noname)
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return NULL;
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} else {
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/*
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* there is an entry for this uid in the password file
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*/
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if (ptr == NULL)
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return pw->pw_name;
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ptr->uid = uid;
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(void)strlcpy(ptr->name, pw->pw_name, sizeof(ptr->name));
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ptr->valid = VALID;
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}
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return ptr->name;
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}
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/*
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* group_from_gid()
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* caches the name (if any) for the gid. If noname clear, we always
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* return the stored name (if valid or invalid match).
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* We use a simple hash table.
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* Return:
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* Pointer to stored name (or a empty string)
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*/
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const char *
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group_from_gid(gid_t gid, int noname)
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{
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struct group grstore, *gr = NULL;
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char grbuf[_GR_BUF_LEN];
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GIDC **pptr, *ptr = NULL;
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if ((gidtb != NULL) || (gidtb_start() == 0)) {
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/*
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* see if we have this gid cached
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*/
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pptr = gidtb + (gid % GID_SZ);
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ptr = *pptr;
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if ((ptr != NULL) && (ptr->valid > 0) && (ptr->gid == gid)) {
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/*
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* have an entry for this gid
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*/
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if (!noname || (ptr->valid == VALID))
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return ptr->name;
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return NULL;
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}
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if (ptr == NULL)
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*pptr = ptr = malloc(sizeof(GIDC));
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}
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getgrgid_r(gid, &grstore, grbuf, sizeof(grbuf), &gr);
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if (gr == NULL) {
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/*
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* no match for this gid in the local group file, put in
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* a string that is the gid in numeric format
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*/
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if (ptr == NULL)
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return NULL;
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ptr->gid = gid;
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(void)snprintf(ptr->name, GNMLEN, "%u", gid);
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ptr->valid = INVALID;
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if (noname)
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return NULL;
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} else {
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/*
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* there is an entry for this group in the group file
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*/
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if (ptr == NULL)
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return gr->gr_name;
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ptr->gid = gid;
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(void)strlcpy(ptr->name, gr->gr_name, sizeof(ptr->name));
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ptr->valid = VALID;
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}
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return ptr->name;
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}
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/*
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* uid_from_user()
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* caches the uid for a given user name. We use a simple hash table.
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* Return:
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* 0 if the user name is found (filling in uid), -1 otherwise
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*/
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int
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uid_from_user(const char *name, uid_t *uid)
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{
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struct passwd pwstore, *pw = NULL;
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char pwbuf[_PW_BUF_LEN];
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UIDC **pptr, *ptr = NULL;
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size_t namelen;
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/*
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* return -1 for mangled names
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*/
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if (name == NULL || ((namelen = strlen(name)) == 0))
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return -1;
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if ((usrtb != NULL) || (usrtb_start() == 0)) {
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/*
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* look up in hash table, if found and valid return the uid,
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* if found and invalid, return a -1
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*/
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pptr = usrtb + st_hash(name, namelen, UNM_SZ);
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ptr = *pptr;
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if ((ptr != NULL) && (ptr->valid > 0) &&
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strcmp(name, ptr->name) == 0) {
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if (ptr->valid == INVALID)
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return -1;
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*uid = ptr->uid;
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return 0;
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}
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if (ptr == NULL)
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*pptr = ptr = malloc(sizeof(UIDC));
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}
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/*
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* no match, look it up, if no match store it as an invalid entry,
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* or store the matching uid
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*/
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getpwnam_r(name, &pwstore, pwbuf, sizeof(pwbuf), &pw);
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if (ptr == NULL) {
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if (pw == NULL)
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return -1;
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*uid = pw->pw_uid;
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return 0;
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}
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(void)strlcpy(ptr->name, name, sizeof(ptr->name));
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if (pw == NULL) {
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ptr->valid = INVALID;
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return -1;
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}
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ptr->valid = VALID;
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*uid = ptr->uid = pw->pw_uid;
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return 0;
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}
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/*
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* gid_from_group()
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* caches the gid for a given group name. We use a simple hash table.
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* Return:
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* 0 if the group name is found (filling in gid), -1 otherwise
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*/
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int
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gid_from_group(const char *name, gid_t *gid)
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{
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struct group grstore, *gr = NULL;
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char grbuf[_GR_BUF_LEN];
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GIDC **pptr, *ptr = NULL;
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size_t namelen;
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/*
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* return -1 for mangled names
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*/
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if (name == NULL || ((namelen = strlen(name)) == 0))
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return -1;
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if ((grptb != NULL) || (grptb_start() == 0)) {
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/*
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* look up in hash table, if found and valid return the uid,
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* if found and invalid, return a -1
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*/
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pptr = grptb + st_hash(name, namelen, GID_SZ);
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ptr = *pptr;
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if ((ptr != NULL) && (ptr->valid > 0) &&
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strcmp(name, ptr->name) == 0) {
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if (ptr->valid == INVALID)
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return -1;
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*gid = ptr->gid;
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return 0;
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}
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if (ptr == NULL)
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*pptr = ptr = malloc(sizeof(GIDC));
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}
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/*
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* no match, look it up, if no match store it as an invalid entry,
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* or store the matching gid
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*/
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getgrnam_r(name, &grstore, grbuf, sizeof(grbuf), &gr);
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if (ptr == NULL) {
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if (gr == NULL)
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return -1;
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*gid = gr->gr_gid;
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return 0;
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}
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(void)strlcpy(ptr->name, name, sizeof(ptr->name));
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if (gr == NULL) {
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ptr->valid = INVALID;
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return -1;
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}
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ptr->valid = VALID;
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*gid = ptr->gid = gr->gr_gid;
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return 0;
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}
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Block a user