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Replace sequence number-based cycle detection in visudo with a

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"used" flag in struct alias.  The caller is required to call
alias_put() when it is done with the alias.  Inspired by a patch
from Daniel Kopecek.
This commit is contained in:
Todd C. Miller
2013-05-22 11:32:08 -04:00
parent 8a57f129ac
commit ab61c02546
8 changed files with 104 additions and 106 deletions
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32
plugins/sudoers/alias.c
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2004-2005, 2007-2012
* Copyright (c) 2004-2005, 2007-2013
* Todd C. Miller <Todd.Miller@courtesan.com>
*
* Permission to use, copy, modify, and distribute this software for any
@@ -49,7 +49,6 @@
* Globals
*/
struct rbtree *aliases;
unsigned int alias_seqno;
/*
* Comparison function for the red-black tree.
@@ -75,35 +74,48 @@ alias_compare(const void *v1, const void *v2)
/*
* Search the tree for an alias with the specified name and type.
* Returns a pointer to the alias structure or NULL if not found.
* Caller is responsible for calling alias_put() on the returned
* alias to mark it as unused.
*/
struct alias *
alias_find(char *name, int type)
alias_get(char *name, int type)
{
struct alias key;
struct rbnode *node;
struct alias *a = NULL;
debug_decl(alias_find, SUDO_DEBUG_ALIAS)
debug_decl(alias_get, SUDO_DEBUG_ALIAS)
key.name = name;
key.type = type;
if ((node = rbfind(aliases, &key)) != NULL) {
/*
* Compare the global sequence number with the one stored
* in the alias. If they match then we've seen this alias
* before and found a loop.
* Check whether this alias is already in use.
* If so, we've detected a loop. If not, set the flag,
* which the caller should clear with a call to alias_put().
*/
a = node->data;
if (a->seqno == alias_seqno) {
if (a->used) {
errno = ELOOP;
debug_return_ptr(NULL);
}
a->seqno = alias_seqno;
a->used = true;
} else {
errno = ENOENT;
}
debug_return_ptr(a);
}
/*
* Clear the "used" flag in an alias once the caller is done with it.
*/
void
alias_put(struct alias *a)
{
debug_decl(alias_put, SUDO_DEBUG_ALIAS)
a->used = false;
debug_return;
}
/*
* Add an alias to the aliases redblack tree.
* Returns NULL on success and an error string on failure.
@@ -118,7 +130,7 @@ alias_add(char *name, int type, struct member *members)
a = ecalloc(1, sizeof(*a));
a->name = name;
a->type = type;
/* a->seqno = 0; */
/* a->used = false; */
list2tq(&a->members, members);
if (rbinsert(aliases, a)) {
snprintf(errbuf, sizeof(errbuf), N_("Alias `%s' already defined"), name);