Initial revision

1 files changed, 584 insertions, 0 deletions

diff --git a/server/acl_files.c b/server/acl_files.c
new file mode 100644
index 0000000..203274c
--- /dev/null
+++ b/server/acl_files.c
@@ -0,0 +1,584 @@
+/* This file is part of the Project Athena Zephyr Notification System.
+ * It contains functions for maintaining Access Control Lists.
+ *
+ *	Created by:	John T. Kohl
+ *
+ *	$Source$
+ *	$Author$
+ *
+ *	Copyright (c) 1987,1988 by the Massachusetts Institute of Technology.
+ *	For copying and distribution information, see the file
+ *	"mit-copyright.h". 
+ */
+
+/* Define this if you really want the ACL-writing code included.  */
+/* #define WRITE_ACL */
+
+/*
+ * Stolen from lib/acl_files.c because acl_load needs to be externally
+ * declared and not statically declared.
+ */
+
+#include <zephyr/mit-copyright.h>
+
+#ifndef lint
+static char rcsid_acl_files_c[] = "$Id$";
+#endif lint
+
+/*** Routines for manipulating access control list files ***/
+
+#include <zephyr/zephyr.h>
+#include <strings.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <ctype.h>
+#include <sys/param.h>			/* for MAXHOSTNAMELEN */
+
+/* "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 64		/* How many acls to cache */
+#define ACL_LEN 256		/* 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';
+    } 
+#ifdef KERBEROS
+    else if(krb_get_lrealm(canon, 1) != KSUCCESS) {
+	strcpy(canon, KRB_REALM);
+    }
+#endif
+}
+	    
+#ifdef notdef
+/* 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);
+    }
+}
+
+/* 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;     
+{
+#ifdef WRITE_ACL
+    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);
+#else
+    abort ();
+#endif
+}
+
+/* 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;     
+{
+#ifdef WRITE_ACL
+    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);
+       }
+#else
+    abort ();
+#endif
+}
+
+/* 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);
+	}
+    }
+}
+
+#endif /* notdef */
+
+/* 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 void
+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;
+
+#if 0
+    fprintf (stderr, "adding %s to acl hash %08X\n", el, h);
+#endif
+    /* 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;
+
+#if 0
+    fprintf (stderr, "looking for %s in acl %08X\n", el, h);
+#endif
+    for(hv = hashval(el) % h->size; h->tbl[hv]; hv = (hv + 1) % h->size) {
+#if 0
+	fprintf (stderr, "\tstrcmp (%s,...)\n", h->tbl[hv]);
+#endif
+	if (!strcmp(h->tbl[hv], el)) {
+#if 0
+	    fprintf (stderr, "success!\n");
+#endif
+	    return 1;
+	}
+    }
+#if 0
+    fprintf (stderr, "failure\n");
+#endif
+    return 0;
+}
+
+struct acl {
+    char filename[LINESIZE];	/* Name of acl file */
+    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 */
+int acl_load(name)
+char *name;
+{
+    int i,fd;
+    FILE *f;
+    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))
+		    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;
+	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);
+    /* Force reload */
+    acl_cache[i].acl = (struct hashtbl *) 0;
+
+ got_it:
+    /*
+     * See if we need to reload the ACL
+     */
+    if (acl_cache[i].acl == (struct hashtbl *) 0) {
+	    /* Gotta reload */
+#if 0
+	   fprintf (stderr, "attempting to load %s\n", name);
+#endif
+	   if ((f = fopen(name, "r")) == NULL) {
+#if 0
+	       perror (name);
+#endif
+	       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);
+       }
+    return(i);
+}
+
+/*
+ * This destroys all cached ACL's so that new ones will be loaded in
+ * the next time they are requested.
+ */
+acl_cache_reset()
+{
+	int	i;
+	
+	/* See if it's there already */
+	for(i = 0; i < acl_cache_count; i++)
+	    if (acl_cache[i].acl) {
+		destroy_hash(acl_cache[i].acl);
+		acl_cache[i].acl = (struct hashtbl *) 0;
+	    }
+	acl_cache_count = 0;
+	acl_cache_next = 0;
+}
+
+
+/* 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;
+
+#if 0
+    fprintf (stderr, "checking for %s in %s\n", principal, acl);
+#endif
+    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);
+}
+
+#ifdef notdef
+/* 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));
+}
+#endif /* notdef */