+/*
+ * $Source: /usr/src/kerberosIV/acl/RCS/acl_files.c,v $
+ * $Author: bostic $
+ *
+ * Copyright 1987,1989 by the Massachusetts Institute of Technology.
+ *
+ * For copying and distribution information, please see the file
+ * <mit-copyright.h>.
+ *
+ */
+
+#ifndef lint
+static char rcsid_acl_files_c[] = "$Id: acl_files.c,v 4.6 91/02/25 15:11:48 bostic Exp $";
+#endif lint
+
+
+/*** Routines for manipulating access control list files ***/
+
+#include <stdio.h>
+#include <strings.h>
+#include <sys/file.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/errno.h>
+#include <ctype.h>
+#include "des.h"
+#include "krb.h"
+
+#ifndef KRB_REALM
+#define KRB_REALM "CS.BERKELEY.EDU"
+#endif
+
+/* "aname.inst@realm" */
+#define MAX_PRINCIPAL_SIZE (ANAME_SZ + INST_SZ + REALM_SZ + 3)
+#define INST_SEP '.'
+#define REALM_SEP '@'
+
+#define LINESIZE 2048 /* Maximum line length in an acl file */
+
+#define NEW_FILE "%s.~NEWACL~" /* Format for name of altered acl file */
+#define WAIT_TIME 300 /* Maximum time allowed write acl file */
+
+#define CACHED_ACLS 8 /* How many acls to cache */
+ /* Each acl costs 1 open file descriptor */
+#define ACL_LEN 16 /* Twice a reasonable acl length */
+
+#define MAX(a,b) (((a)>(b))?(a):(b))
+#define MIN(a,b) (((a)<(b))?(a):(b))
+
+#define COR(a,b) ((a!=NULL)?(a):(b))
+
+extern int errno;
+
+extern char *malloc(), *calloc();
+extern time_t time();
+
+/* Canonicalize a principal name */
+/* If instance is missing, it becomes "" */
+/* If realm is missing, it becomes the local realm */
+/* Canonicalized form is put in canon, which must be big enough to hold
+ MAX_PRINCIPAL_SIZE characters */
+acl_canonicalize_principal(principal, canon)
+char *principal;
+char *canon;
+{
+ char *dot, *atsign, *end;
+ int len;
+
+ dot = index(principal, INST_SEP);
+ atsign = index(principal, REALM_SEP);
+
+ /* Maybe we're done already */
+ if(dot != NULL && atsign != NULL) {
+ if(dot < atsign) {
+ /* It's for real */
+ /* Copy into canon */
+ strncpy(canon, principal, MAX_PRINCIPAL_SIZE);
+ canon[MAX_PRINCIPAL_SIZE-1] = '\0';
+ return;
+ } else {
+ /* Nope, it's part of the realm */
+ dot = NULL;
+ }
+ }
+
+ /* No such luck */
+ end = principal + strlen(principal);
+
+ /* Get the principal name */
+ len = MIN(ANAME_SZ, COR(dot, COR(atsign, end)) - principal);
+ strncpy(canon, principal, len);
+ canon += len;
+
+ /* Add INST_SEP */
+ *canon++ = INST_SEP;
+
+ /* Get the instance, if it exists */
+ if(dot != NULL) {
+ ++dot;
+ len = MIN(INST_SZ, COR(atsign, end) - dot);
+ strncpy(canon, dot, len);
+ canon += len;
+ }
+
+ /* Add REALM_SEP */
+ *canon++ = REALM_SEP;
+
+ /* Get the realm, if it exists */
+ /* Otherwise, default to local realm */
+ if(atsign != NULL) {
+ ++atsign;
+ len = MIN(REALM_SZ, end - atsign);
+ strncpy(canon, atsign, len);
+ canon += len;
+ *canon++ = '\0';
+ } else if(krb_get_lrealm(canon, 1) != KSUCCESS) {
+ strcpy(canon, KRB_REALM);
+ }
+}
+
+/* Get a lock to modify acl_file */
+/* Return new FILE pointer */
+/* or NULL if file cannot be modified */
+/* REQUIRES WRITE PERMISSION TO CONTAINING DIRECTORY */
+static FILE *acl_lock_file(acl_file)
+char *acl_file;
+{
+ struct stat s;
+ char new[LINESIZE];
+ int nfd;
+ FILE *nf;
+ int mode;
+
+ if(stat(acl_file, &s) < 0) return(NULL);
+ mode = s.st_mode;
+ sprintf(new, NEW_FILE, acl_file);
+ for(;;) {
+ /* Open the new file */
+ if((nfd = open(new, O_WRONLY|O_CREAT|O_EXCL, mode)) < 0) {
+ if(errno == EEXIST) {
+ /* Maybe somebody got here already, maybe it's just old */
+ if(stat(new, &s) < 0) return(NULL);
+ if(time(0) - s.st_ctime > WAIT_TIME) {
+ /* File is stale, kill it */
+ unlink(new);
+ continue;
+ } else {
+ /* Wait and try again */
+ sleep(1);
+ continue;
+ }
+ } else {
+ /* Some other error, we lose */
+ return(NULL);
+ }
+ }
+
+ /* If we got to here, the lock file is ours and ok */
+ /* Reopen it under stdio */
+ if((nf = fdopen(nfd, "w")) == NULL) {
+ /* Oops, clean up */
+ unlink(new);
+ }
+ return(nf);
+ }
+}
+
+static int acl_abort();
+
+/* Commit changes to acl_file written onto FILE *f */
+/* Returns zero if successful */
+/* Returns > 0 if lock was broken */
+/* Returns < 0 if some other error occurs */
+/* Closes f */
+static int acl_commit(acl_file, f)
+char *acl_file;
+FILE *f;
+{
+ char new[LINESIZE];
+ int ret;
+ struct stat s;
+
+ sprintf(new, NEW_FILE, acl_file);
+ if(fflush(f) < 0
+ || fstat(fileno(f), &s) < 0
+ || s.st_nlink == 0) {
+ acl_abort(acl_file, f);
+ return(-1);
+ }
+
+ ret = rename(new, acl_file);
+ fclose(f);
+ return(ret);
+}
+
+/* Abort changes to acl_file written onto FILE *f */
+/* Returns 0 if successful, < 0 otherwise */
+/* Closes f */
+static int acl_abort(acl_file, f)
+char *acl_file;
+FILE *f;
+{
+ char new[LINESIZE];
+ int ret;
+ struct stat s;
+
+ /* make sure we aren't nuking someone else's file */
+ if(fstat(fileno(f), &s) < 0
+ || s.st_nlink == 0) {
+ fclose(f);
+ return(-1);
+ } else {
+ sprintf(new, NEW_FILE, acl_file);
+ ret = unlink(new);
+ fclose(f);
+ return(ret);
+ }
+}
+
+/* Initialize an acl_file */
+/* Creates the file with permissions perm if it does not exist */
+/* Erases it if it does */
+/* Returns return value of acl_commit */
+int acl_initialize(acl_file, perm)
+char *acl_file;
+int perm;
+{
+ FILE *new;
+ int fd;
+
+ /* Check if the file exists already */
+ if((new = acl_lock_file(acl_file)) != NULL) {
+ return(acl_commit(acl_file, new));
+ } else {
+ /* File must be readable and writable by owner */
+ if((fd = open(acl_file, O_CREAT|O_EXCL, perm|0600)) < 0) {
+ return(-1);
+ } else {
+ close(fd);
+ return(0);
+ }
+ }
+}
+
+/* Eliminate all whitespace character in buf */
+/* Modifies its argument */
+static nuke_whitespace(buf)
+char *buf;
+{
+ register char *pin, *pout;
+
+ for(pin = pout = buf; *pin != '\0'; pin++)
+ if(!isspace(*pin)) *pout++ = *pin;
+ *pout = '\0'; /* Terminate the string */
+}
+
+/* Hash table stuff */
+
+struct hashtbl {
+ int size; /* Max number of entries */
+ int entries; /* Actual number of entries */
+ char **tbl; /* Pointer to start of table */
+};
+
+/* Make an empty hash table of size s */
+static struct hashtbl *make_hash(size)
+int size;
+{
+ struct hashtbl *h;
+
+ if(size < 1) size = 1;
+ h = (struct hashtbl *) malloc(sizeof(struct hashtbl));
+ h->size = size;
+ h->entries = 0;
+ h->tbl = (char **) calloc(size, sizeof(char *));
+ return(h);
+}
+
+/* Destroy a hash table */
+static destroy_hash(h)
+struct hashtbl *h;
+{
+ int i;
+
+ for(i = 0; i < h->size; i++) {
+ if(h->tbl[i] != NULL) free(h->tbl[i]);
+ }
+ free(h->tbl);
+ free(h);
+}
+
+/* Compute hash value for a string */
+static unsigned hashval(s)
+register char *s;
+{
+ register unsigned hv;
+
+ for(hv = 0; *s != '\0'; s++) {
+ hv ^= ((hv << 3) ^ *s);
+ }
+ return(hv);
+}
+
+/* Add an element to a hash table */
+static add_hash(h, el)
+struct hashtbl *h;
+char *el;
+{
+ unsigned hv;
+ char *s;
+ char **old;
+ int i;
+
+ /* Make space if it isn't there already */
+ if(h->entries + 1 > (h->size >> 1)) {
+ old = h->tbl;
+ h->tbl = (char **) calloc(h->size << 1, sizeof(char *));
+ for(i = 0; i < h->size; i++) {
+ if(old[i] != NULL) {
+ hv = hashval(old[i]) % (h->size << 1);
+ while(h->tbl[hv] != NULL) hv = (hv+1) % (h->size << 1);
+ h->tbl[hv] = old[i];
+ }
+ }
+ h->size = h->size << 1;
+ free(old);
+ }
+
+ hv = hashval(el) % h->size;
+ while(h->tbl[hv] != NULL && strcmp(h->tbl[hv], el)) hv = (hv+1) % h->size;
+ s = malloc(strlen(el)+1);
+ strcpy(s, el);
+ h->tbl[hv] = s;
+ h->entries++;
+}
+
+/* Returns nonzero if el is in h */
+static check_hash(h, el)
+struct hashtbl *h;
+char *el;
+{
+ unsigned hv;
+
+ for(hv = hashval(el) % h->size;
+ h->tbl[hv] != NULL;
+ hv = (hv + 1) % h->size) {
+ if(!strcmp(h->tbl[hv], el)) return(1);
+ }
+ return(0);
+}
+
+struct acl {
+ char filename[LINESIZE]; /* Name of acl file */
+ int fd; /* File descriptor for acl file */
+ struct stat status; /* File status at last read */
+ struct hashtbl *acl; /* Acl entries */
+};
+
+static struct acl acl_cache[CACHED_ACLS];
+
+static int acl_cache_count = 0;
+static int acl_cache_next = 0;
+
+/* Returns < 0 if unsuccessful in loading acl */
+/* Returns index into acl_cache otherwise */
+/* Note that if acl is already loaded, this is just a lookup */
+static int acl_load(name)
+char *name;
+{
+ int i;
+ FILE *f;
+ struct stat s;
+ char buf[MAX_PRINCIPAL_SIZE];
+ char canon[MAX_PRINCIPAL_SIZE];
+
+ /* See if it's there already */
+ for(i = 0; i < acl_cache_count; i++) {
+ if(!strcmp(acl_cache[i].filename, name)
+ && acl_cache[i].fd >= 0) goto got_it;
+ }
+
+ /* It isn't, load it in */
+ /* maybe there's still room */
+ if(acl_cache_count < CACHED_ACLS) {
+ i = acl_cache_count++;
+ } else {
+ /* No room, clean one out */
+ i = acl_cache_next;
+ acl_cache_next = (acl_cache_next + 1) % CACHED_ACLS;
+ close(acl_cache[i].fd);
+ if(acl_cache[i].acl) {
+ destroy_hash(acl_cache[i].acl);
+ acl_cache[i].acl = (struct hashtbl *) 0;
+ }
+ }
+
+ /* Set up the acl */
+ strcpy(acl_cache[i].filename, name);
+ if((acl_cache[i].fd = open(name, O_RDONLY, 0)) < 0) return(-1);
+ /* Force reload */
+ acl_cache[i].acl = (struct hashtbl *) 0;
+
+ got_it:
+ /*
+ * See if the stat matches
+ *
+ * Use stat(), not fstat(), as the file may have been re-created by
+ * acl_add or acl_delete. If this happens, the old inode will have
+ * no changes in the mod-time and the following test will fail.
+ */
+ if(stat(acl_cache[i].filename, &s) < 0) return(-1);
+ if(acl_cache[i].acl == (struct hashtbl *) 0
+ || s.st_nlink != acl_cache[i].status.st_nlink
+ || s.st_mtime != acl_cache[i].status.st_mtime
+ || s.st_ctime != acl_cache[i].status.st_ctime) {
+ /* Gotta reload */
+ if(acl_cache[i].fd >= 0) close(acl_cache[i].fd);
+ if((acl_cache[i].fd = open(name, O_RDONLY, 0)) < 0) return(-1);
+ if((f = fdopen(acl_cache[i].fd, "r")) == NULL) return(-1);
+ if(acl_cache[i].acl) destroy_hash(acl_cache[i].acl);
+ acl_cache[i].acl = make_hash(ACL_LEN);
+ while(fgets(buf, sizeof(buf), f) != NULL) {
+ nuke_whitespace(buf);
+ acl_canonicalize_principal(buf, canon);
+ add_hash(acl_cache[i].acl, canon);
+ }
+ fclose(f);
+ acl_cache[i].status = s;
+ }
+ return(i);
+}
+
+/* Returns nonzero if it can be determined that acl contains principal */
+/* Principal is not canonicalized, and no wildcarding is done */
+acl_exact_match(acl, principal)
+char *acl;
+char *principal;
+{
+ int idx;
+
+ return((idx = acl_load(acl)) >= 0
+ && check_hash(acl_cache[idx].acl, principal));
+}
+
+/* Returns nonzero if it can be determined that acl contains principal */
+/* Recognizes wildcards in acl of the form
+ name.*@realm, *.*@realm, and *.*@* */
+acl_check(acl, principal)
+char *acl;
+char *principal;
+{
+ char buf[MAX_PRINCIPAL_SIZE];
+ char canon[MAX_PRINCIPAL_SIZE];
+ char *realm;
+
+ acl_canonicalize_principal(principal, canon);
+
+ /* Is it there? */
+ if(acl_exact_match(acl, canon)) return(1);
+
+ /* Try the wildcards */
+ realm = index(canon, REALM_SEP);
+ *index(canon, INST_SEP) = '\0'; /* Chuck the instance */
+
+ sprintf(buf, "%s.*%s", canon, realm);
+ if(acl_exact_match(acl, buf)) return(1);
+
+ sprintf(buf, "*.*%s", realm);
+ if(acl_exact_match(acl, buf) || acl_exact_match(acl, "*.*@*")) return(1);
+
+ return(0);
+}
+
+/* Adds principal to acl */
+/* Wildcards are interpreted literally */
+acl_add(acl, principal)
+char *acl;
+char *principal;
+{
+ int idx;
+ int i;
+ FILE *new;
+ char canon[MAX_PRINCIPAL_SIZE];
+
+ acl_canonicalize_principal(principal, canon);
+
+ if((new = acl_lock_file(acl)) == NULL) return(-1);
+ if((acl_exact_match(acl, canon))
+ || (idx = acl_load(acl)) < 0) {
+ acl_abort(acl, new);
+ return(-1);
+ }
+ /* It isn't there yet, copy the file and put it in */
+ for(i = 0; i < acl_cache[idx].acl->size; i++) {
+ if(acl_cache[idx].acl->tbl[i] != NULL) {
+ if(fputs(acl_cache[idx].acl->tbl[i], new) == NULL
+ || putc('\n', new) != '\n') {
+ acl_abort(acl, new);
+ return(-1);
+ }
+ }
+ }
+ fputs(canon, new);
+ putc('\n', new);
+ return(acl_commit(acl, new));
+}
+
+/* Removes principal from acl */
+/* Wildcards are interpreted literally */
+acl_delete(acl, principal)
+char *acl;
+char *principal;
+{
+ int idx;
+ int i;
+ FILE *new;
+ char canon[MAX_PRINCIPAL_SIZE];
+
+ acl_canonicalize_principal(principal, canon);
+
+ if((new = acl_lock_file(acl)) == NULL) return(-1);
+ if((!acl_exact_match(acl, canon))
+ || (idx = acl_load(acl)) < 0) {
+ acl_abort(acl, new);
+ return(-1);
+ }
+ /* It isn't there yet, copy the file and put it in */
+ for(i = 0; i < acl_cache[idx].acl->size; i++) {
+ if(acl_cache[idx].acl->tbl[i] != NULL
+ && strcmp(acl_cache[idx].acl->tbl[i], canon)) {
+ fputs(acl_cache[idx].acl->tbl[i], new);
+ putc('\n', new);
+ }
+ }
+ return(acl_commit(acl, new));
+}
+
projects / unix-history / commitdiff