/* $OpenBSD: pwcache.c,v 1.16 2022/12/27 17:10:06 jmc Exp $ */ /*- * Copyright (c) 1992 Keith Muller. * Copyright (c) 1992, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Keith Muller of the University of California, San Diego. * * 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. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include <sys/types.h> #include <assert.h> #include <grp.h> #include <pwd.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> /* * Constants and data structures used to implement group and password file * caches. Name lengths have been chosen to be as large as those supported * by the passwd and group files as well as the standard archive formats. * CACHE SIZES MUST BE PRIME */ #define UNMLEN 32 /* >= user name found in any protocol */ #define GNMLEN 32 /* >= group name found in any protocol */ #define UID_SZ 317 /* size of uid to user_name cache */ #define UNM_SZ 317 /* size of user_name to uid cache */ #define GID_SZ 251 /* size of gid to group_name cache */ #define GNM_SZ 251 /* size of group_name to gid cache */ #define VALID 1 /* entry and name are valid */ #define INVALID 2 /* entry valid, name NOT valid */ /* * Node structures used in the user, group, uid, and gid caches. */ typedef struct uidc { int valid; /* is this a valid or a miss entry */ char name[UNMLEN]; /* uid name */ uid_t uid; /* cached uid */ } UIDC; typedef struct gidc { int valid; /* is this a valid or a miss entry */ char name[GNMLEN]; /* gid name */ gid_t gid; /* cached gid */ } GIDC; /* * Routines that control user, group, uid and gid caches. * Traditional passwd/group cache routines perform quite poorly with * archives. The chances of hitting a valid lookup with an archive is quite a * bit worse than with files already resident on the file system. These misses * create a MAJOR performance cost. To address this problem, these routines * cache both hits and misses. */ static UIDC **uidtb; /* uid to name cache */ static GIDC **gidtb; /* gid to name cache */ static UIDC **usrtb; /* user name to uid cache */ static GIDC **grptb; /* group name to gid cache */ static u_int st_hash(const char *name, size_t len, int tabsz) { u_int key = 0; assert(name != NULL); while (len--) { key += *name++; key = (key << 8) | (key >> 24); } return key % tabsz; } /* * uidtb_start * creates an an empty uidtb * Return: * 0 if ok, -1 otherwise */ static int uidtb_start(void) { static int fail = 0; if (uidtb != NULL) return 0; if (fail) return -1; if ((uidtb = calloc(UID_SZ, sizeof(UIDC *))) == NULL) { ++fail; return -1; } return 0; } /* * gidtb_start * creates an an empty gidtb * Return: * 0 if ok, -1 otherwise */ static int gidtb_start(void) { static int fail = 0; if (gidtb != NULL) return 0; if (fail) return -1; if ((gidtb = calloc(GID_SZ, sizeof(GIDC *))) == NULL) { ++fail; return -1; } return 0; } /* * usrtb_start * creates an an empty usrtb * Return: * 0 if ok, -1 otherwise */ static int usrtb_start(void) { static int fail = 0; if (usrtb != NULL) return 0; if (fail) return -1; if ((usrtb = calloc(UNM_SZ, sizeof(UIDC *))) == NULL) { ++fail; return -1; } return 0; } /* * grptb_start * creates an an empty grptb * Return: * 0 if ok, -1 otherwise */ static int grptb_start(void) { static int fail = 0; if (grptb != NULL) return 0; if (fail) return -1; if ((grptb = calloc(GNM_SZ, sizeof(GIDC *))) == NULL) { ++fail; return -1; } return 0; } /* * user_from_uid() * caches the name (if any) for the uid. If noname clear, we always * return the stored name (if valid or invalid match). * We use a simple hash table. * Return: * Pointer to stored name (or a empty string) */ const char * user_from_uid(uid_t uid, int noname) { struct passwd pwstore, *pw = NULL; char pwbuf[_PW_BUF_LEN]; UIDC **pptr, *ptr = NULL; if ((uidtb != NULL) || (uidtb_start() == 0)) { /* * see if we have this uid cached */ pptr = uidtb + (uid % UID_SZ); ptr = *pptr; if ((ptr != NULL) && (ptr->valid > 0) && (ptr->uid == uid)) { /* * have an entry for this uid */ if (!noname || (ptr->valid == VALID)) return ptr->name; return NULL; } if (ptr == NULL) *pptr = ptr = malloc(sizeof(UIDC)); } getpwuid_r(uid, &pwstore, pwbuf, sizeof(pwbuf), &pw); if (pw == NULL) { /* * no match for this uid in the local password file * a string that is the uid in numeric format */ if (ptr == NULL) return NULL; ptr->uid = uid; (void)snprintf(ptr->name, UNMLEN, "%u", uid); ptr->valid = INVALID; if (noname) return NULL; } else { /* * there is an entry for this uid in the password file */ if (ptr == NULL) return pw->pw_name; ptr->uid = uid; (void)strlcpy(ptr->name, pw->pw_name, sizeof(ptr->name)); ptr->valid = VALID; } return ptr->name; } /* * group_from_gid() * caches the name (if any) for the gid. If noname clear, we always * return the stored name (if valid or invalid match). * We use a simple hash table. * Return: * Pointer to stored name (or a empty string) */ const char * group_from_gid(gid_t gid, int noname) { struct group grstore, *gr = NULL; char grbuf[_GR_BUF_LEN]; GIDC **pptr, *ptr = NULL; if ((gidtb != NULL) || (gidtb_start() == 0)) { /* * see if we have this gid cached */ pptr = gidtb + (gid % GID_SZ); ptr = *pptr; if ((ptr != NULL) && (ptr->valid > 0) && (ptr->gid == gid)) { /* * have an entry for this gid */ if (!noname || (ptr->valid == VALID)) return ptr->name; return NULL; } if (ptr == NULL) *pptr = ptr = malloc(sizeof(GIDC)); } getgrgid_r(gid, &grstore, grbuf, sizeof(grbuf), &gr); if (gr == NULL) { /* * no match for this gid in the local group file, put in * a string that is the gid in numeric format */ if (ptr == NULL) return NULL; ptr->gid = gid; (void)snprintf(ptr->name, GNMLEN, "%u", gid); ptr->valid = INVALID; if (noname) return NULL; } else { /* * there is an entry for this group in the group file */ if (ptr == NULL) return gr->gr_name; ptr->gid = gid; (void)strlcpy(ptr->name, gr->gr_name, sizeof(ptr->name)); ptr->valid = VALID; } return ptr->name; } /* * uid_from_user() * caches the uid for a given user name. We use a simple hash table. * Return: * 0 if the user name is found (filling in uid), -1 otherwise */ int uid_from_user(const char *name, uid_t *uid) { struct passwd pwstore, *pw = NULL; char pwbuf[_PW_BUF_LEN]; UIDC **pptr, *ptr = NULL; size_t namelen; /* * return -1 for mangled names */ if (name == NULL || ((namelen = strlen(name)) == 0)) return -1; if ((usrtb != NULL) || (usrtb_start() == 0)) { /* * look up in hash table, if found and valid return the uid, * if found and invalid, return a -1 */ pptr = usrtb + st_hash(name, namelen, UNM_SZ); ptr = *pptr; if ((ptr != NULL) && (ptr->valid > 0) && strcmp(name, ptr->name) == 0) { if (ptr->valid == INVALID) return -1; *uid = ptr->uid; return 0; } if (ptr == NULL) *pptr = ptr = malloc(sizeof(UIDC)); } /* * no match, look it up, if no match store it as an invalid entry, * or store the matching uid */ getpwnam_r(name, &pwstore, pwbuf, sizeof(pwbuf), &pw); if (ptr == NULL) { if (pw == NULL) return -1; *uid = pw->pw_uid; return 0; } (void)strlcpy(ptr->name, name, sizeof(ptr->name)); if (pw == NULL) { ptr->valid = INVALID; return -1; } ptr->valid = VALID; *uid = ptr->uid = pw->pw_uid; return 0; } /* * gid_from_group() * caches the gid for a given group name. We use a simple hash table. * Return: * 0 if the group name is found (filling in gid), -1 otherwise */ int gid_from_group(const char *name, gid_t *gid) { struct group grstore, *gr = NULL; char grbuf[_GR_BUF_LEN]; GIDC **pptr, *ptr = NULL; size_t namelen; /* * return -1 for mangled names */ if (name == NULL || ((namelen = strlen(name)) == 0)) return -1; if ((grptb != NULL) || (grptb_start() == 0)) { /* * look up in hash table, if found and valid return the uid, * if found and invalid, return a -1 */ pptr = grptb + st_hash(name, namelen, GID_SZ); ptr = *pptr; if ((ptr != NULL) && (ptr->valid > 0) && strcmp(name, ptr->name) == 0) { if (ptr->valid == INVALID) return -1; *gid = ptr->gid; return 0; } if (ptr == NULL) *pptr = ptr = malloc(sizeof(GIDC)); } /* * no match, look it up, if no match store it as an invalid entry, * or store the matching gid */ getgrnam_r(name, &grstore, grbuf, sizeof(grbuf), &gr); if (ptr == NULL) { if (gr == NULL) return -1; *gid = gr->gr_gid; return 0; } (void)strlcpy(ptr->name, name, sizeof(ptr->name)); if (gr == NULL) { ptr->valid = INVALID; return -1; } ptr->valid = VALID; *gid = ptr->gid = gr->gr_gid; return 0; }
