diff options
Diffstat (limited to 'crypto/kerberosIV/lib/acl')
| -rw-r--r-- | crypto/kerberosIV/lib/acl/Makefile.in | 84 | ||||
| -rw-r--r-- | crypto/kerberosIV/lib/acl/acl.h | 53 | ||||
| -rw-r--r-- | crypto/kerberosIV/lib/acl/acl_files.c | 540 | ||||
| -rw-r--r-- | crypto/kerberosIV/lib/acl/acl_files.doc | 107 |
4 files changed, 784 insertions, 0 deletions
diff --git a/crypto/kerberosIV/lib/acl/Makefile.in b/crypto/kerberosIV/lib/acl/Makefile.in new file mode 100644 index 0000000..59894e4 --- /dev/null +++ b/crypto/kerberosIV/lib/acl/Makefile.in @@ -0,0 +1,84 @@ +# +# $Id: Makefile.in,v 1.21 1997/05/06 03:46:37 assar Exp $ +# + +SHELL = /bin/sh + +srcdir = @srcdir@ +VPATH = @srcdir@ + +CC = @CC@ +AR = ar +RANLIB = @RANLIB@ +DEFS = @DEFS@ +CFLAGS = @CFLAGS@ + +INSTALL = @INSTALL@ +INSTALL_DATA = @INSTALL_DATA@ +MKINSTALLDIRS = @top_srcdir@/mkinstalldirs + +prefix = @prefix@ +exec_prefix = @exec_prefix@ +libdir = @libdir@ + +PICFLAGS = # @PICFLAGS@ + +LIBNAME = $(LIBPREFIX)acl +#LIBEXT = @LIBEXT@ Always build archive library! +LIBEXT = a +LIBPREFIX = @LIBPREFIX@ +SHLIBEXT = @SHLIBEXT@ +LDSHARED = @LDSHARED@ +LIB = $(LIBNAME).$(LIBEXT) + +SOURCES = acl_files.c + +OBJECTS = acl_files.o + +all: $(LIB) + +Wall: + make CFLAGS="-g -Wall -Wno-comment -Wmissing-prototypes -Wmissing-declarations -D__USE_FIXED_PROTOTYPES__" + +.c.o: + $(CC) -c $(CPPFLAGS) $(DEFS) -I../../include -I$(srcdir) $(CFLAGS) $(PICFLAGS) $< + +install: all + $(MKINSTALLDIRS) $(libdir) + $(INSTALL_DATA) -m 0555 $(LIB) $(libdir) + +uninstall: + rm -f $(libdir)/$(LIB) + +TAGS: $(SOURCES) + etags $(SOURCES) + +check: + +clean: + rm -f $(LIB) *.o *.a + +mostlyclean: clean + +distclean: clean + rm -f Makefile *.tab.c *~ + +realclean: distclean + rm -f TAGS + +dist: $(DISTFILES) + for file in $(DISTFILES); do \ + ln $$file ../`cat ../.fname`/lib \ + || cp -p $$file ../`cat ../.fname`/lib; \ + done + +$(LIBNAME).a: $(OBJECTS) + rm -f $@ + $(AR) cr $@ $(OBJECTS) + -$(RANLIB) $@ + +$(LIBNAME).$(SHLIBEXT): $(OBJECTS) + rm -f $@ + $(LDSHARED) -o $@ $(OBJECTS) + +$(OBJECTS): ../../include/config.h diff --git a/crypto/kerberosIV/lib/acl/acl.h b/crypto/kerberosIV/lib/acl/acl.h new file mode 100644 index 0000000..305b66c --- /dev/null +++ b/crypto/kerberosIV/lib/acl/acl.h @@ -0,0 +1,53 @@ +/* + * Copyright (c) 1995, 1996, 1997 Kungliga Tekniska Högskolan + * (Royal Institute of Technology, Stockholm, Sweden). + * 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. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the Kungliga Tekniska + * Högskolan and its contributors. + * + * 4. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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. + */ + +/* $Id: acl.h,v 1.5 1997/04/01 08:17:52 joda Exp $ */ + +#ifndef __ACL_H +#define __ACL_H + +#include <sys/cdefs.h> + +void acl_canonicalize_principal __P((char *principal, char *canon)); +int acl_initialize __P((char *acl_file, int perm)); +int acl_exact_match __P((char *acl, char *principal)); +int acl_check __P((char *acl, char *principal)); +int acl_add __P((char *acl, char *principal)); +int acl_delete __P((char *acl, char *principal)); + +#endif /* __ACL_H */ diff --git a/crypto/kerberosIV/lib/acl/acl_files.c b/crypto/kerberosIV/lib/acl/acl_files.c new file mode 100644 index 0000000..fc00b80 --- /dev/null +++ b/crypto/kerberosIV/lib/acl/acl_files.c @@ -0,0 +1,540 @@ +/* + Copyright (C) 1989 by the Massachusetts Institute of Technology + + Export of this software from the United States of America is assumed + to require a specific license from the United States Government. + It is the responsibility of any person or organization contemplating + export to obtain such a license before exporting. + +WITHIN THAT CONSTRAINT, permission to use, copy, modify, and +distribute this software and its documentation for any purpose and +without fee is hereby granted, provided that the above copyright +notice appear in all copies and that both that copyright notice and +this permission notice appear in supporting documentation, and that +the name of M.I.T. not be used in advertising or publicity pertaining +to distribution of the software without specific, written prior +permission. M.I.T. makes no representations about the suitability of +this software for any purpose. It is provided "as is" without express +or implied warranty. + + */ + +#include "config.h" +#include "protos.h" + +RCSID("$Id: acl_files.c,v 1.10 1997/05/02 14:28:56 assar Exp $"); + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#ifdef HAVE_UNISTD_H +#include <unistd.h> +#endif +#ifdef HAVE_SYS_TYPES_H +#include <sys/types.h> +#endif +#include <time.h> +#ifdef HAVE_FCNTL_H +#include <fcntl.h> +#endif +#ifdef HAVE_SYS_FILE_H +#include <sys/file.h> +#endif +#ifdef HAVE_SYS_STAT_H +#include <sys/stat.h> +#endif + +#include <errno.h> +#include <ctype.h> + +#include <roken.h> + +#include <krb.h> +#include <acl.h> + +/*** Routines for manipulating access control list files ***/ + +/* "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 COR(a,b) ((a!=NULL)?(a):(b)) + +/* 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 */ +void +acl_canonicalize_principal(char *principal, char *canon) +{ + char *dot, *atsign, *end; + int len; + + dot = strchr(principal, INST_SEP); + atsign = strchr(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(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; + snprintf(new, sizeof(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); + } +} + +/* Abort changes to acl_file written onto FILE *f */ +/* Returns 0 if successful, < 0 otherwise */ +/* Closes f */ +static int +acl_abort(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 { + snprintf(new, sizeof(new), NEW_FILE, acl_file); + ret = unlink(new); + fclose(f); + return(ret); + } +} + +/* 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(char *acl_file, FILE *f) +{ + char new[LINESIZE]; + int ret; + struct stat s; + + snprintf(new, sizeof(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); +} + +/* 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(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 void + nuke_whitespace(char *buf) +{ + 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(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 void +destroy_hash(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 int +hashval(char *s) +{ + unsigned hv; + + for(hv = 0; *s != '\0'; s++) { + hv ^= ((hv << 3) ^ *s); + } + return(hv); +} + +/* Add an element to a hash table */ +static void +add_hash(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 = strdup(el); + h->tbl[hv] = s; + h->entries++; +} + +/* Returns nonzero if el is in h */ +static int +check_hash(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(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 */ +int +acl_exact_match(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 *.*@* */ +int +acl_check(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 = strchr(canon, REALM_SEP); + *strchr(canon, INST_SEP) = '\0'; /* Chuck the instance */ + + snprintf(buf, sizeof(buf), "%s.*%s", canon, realm); + if(acl_exact_match(acl, buf)) return(1); + + snprintf(buf, sizeof(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 */ +int +acl_add(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) == EOF + || 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 */ +int +acl_delete(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)); +} diff --git a/crypto/kerberosIV/lib/acl/acl_files.doc b/crypto/kerberosIV/lib/acl/acl_files.doc new file mode 100644 index 0000000..78c448a --- /dev/null +++ b/crypto/kerberosIV/lib/acl/acl_files.doc @@ -0,0 +1,107 @@ +PROTOTYPE ACL LIBRARY + +Introduction + +An access control list (ACL) is a list of principals, where each +principal is is represented by a text string which cannot contain +whitespace. The library allows application programs to refer to named +access control lists to test membership and to atomically add and +delete principals using a natural and intuitive interface. At +present, the names of access control lists are required to be Unix +filenames, and refer to human-readable Unix files; in the future, when +a networked ACL server is implemented, the names may refer to a +different namespace specific to the ACL service. + + +Usage + +cc <files> -lacl -lkrb. + + + +Principal Names + +Principal names have the form + +<name>[.<instance>][@<realm>] + +e.g. + +asp +asp.root +asp@ATHENA.MIT.EDU +asp.@ATHENA.MIT.EDU +asp.root@ATHENA.MIT.EDU + +It is possible for principals to be underspecified. If instance is +missing, it is assumed to be "". If realm is missing, it is assumed +to be local_realm. The canonical form contains all of name, instance, +and realm; the acl_add and acl_delete routines will always +leave the file in that form. Note that the canonical form of +asp@ATHENA.MIT.EDU is actually asp.@ATHENA.MIT.EDU. + + +Routines + +acl_canonicalize_principal(principal, buf) +char *principal; +char *buf; /*RETVAL*/ + +Store the canonical form of principal in buf. Buf must contain enough +space to store a principal, given the limits on the sizes of name, +instance, and realm specified in /usr/include/krb.h. + +acl_check(acl, principal) +char *acl; +char *principal; + +Returns nonzero if principal appears in acl. Returns 0 if principal +does not appear in acl, or if an error occurs. Canonicalizes +principal before checking, and allows the ACL to contain wildcards. + +acl_exact_match(acl, principal) +char *acl; +char *principal; + +Like acl_check, but does no canonicalization or wildcarding. + +acl_add(acl, principal) +char *acl; +char *principal; + +Atomically adds principal to acl. Returns 0 if successful, nonzero +otherwise. It is considered a failure if principal is already in acl. +This routine will canonicalize principal, but will treat wildcards +literally. + +acl_delete(acl, principal) +char *acl; +char *principal; + +Atomically deletes principal from acl. Returns 0 if successful, +nonzero otherwise. It is consider a failure if principal is not +already in acl. This routine will canonicalize principal, but will +treat wildcards literally. + +acl_initialize(acl, mode) +char *acl; +int mode; + +Initialize acl. If acl file does not exist, creates it with mode +mode. If acl exists, removes all members. Returns 0 if successful, +nonzero otherwise. WARNING: Mode argument is likely to change with +the eventual introduction of an ACL service. + + +Known problems + +In the presence of concurrency, there is a very small chance that +acl_add or acl_delete could report success even though it would have +had no effect. This is a necessary side effect of using lock files +for concurrency control rather than flock(2), which is not supported +by NFS. + +The current implementation caches ACLs in memory in a hash-table +format for increased efficiency in checking membership; one effect of +the caching scheme is that one file descriptor will be kept open for +each ACL cached, up to a maximum of 8. |
