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Fix potential crash introduced in the fix for GitHub issue #134.

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If a user's sudoers entry did not have any RunAs user's set, running
"sudo -U otheruser -l" would dereference a NULL pointer.  We need
to compare the default RunAs user if the sudoers entry does not
specify one explicitly.  Problem reported by Andreas Mueller who
also suggested a different solution in PR #219.
This commit is contained in:
Todd C. Miller
2022-12-07 10:25:00 -07:00
parent 31684dccc0
commit f5488d733d
1 changed files with 20 additions and 5 deletions
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25
plugins/sudoers/parse.c
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@@ -35,6 +35,23 @@
#include "sudo_lbuf.h" #include "sudo_lbuf.h"
#include <gram.h> #include <gram.h>
static int
runas_matches_pw(struct sudoers_parse_tree *parse_tree,
const struct cmndspec *cs, const struct passwd *pw)
{
debug_decl(runas_matches_pw, SUDOERS_DEBUG_PARSER);
if (cs->runasuserlist != NULL)
debug_return_int(userlist_matches(parse_tree, pw, cs->runasuserlist));
if (cs->runasgrouplist == NULL) {
/* No explicit runas user or group, use default. */
if (userpw_matches(def_runas_default, pw->pw_name, pw))
debug_return_int(ALLOW);
}
debug_return_int(UNSPEC);
}
/* /*
* Look up the user in the sudoers parse tree for pseudo-commands like * Look up the user in the sudoers parse tree for pseudo-commands like
* list, verify and kill. * list, verify and kill.
@@ -101,12 +118,10 @@ sudoers_lookup_pseudo(struct sudo_nss_list *snl, struct passwd *pw,
continue; continue;
} }
/* Runas user must match list user or root. */ /* Runas user must match list user or root. */
if (userlist_matches(nss->parse_tree, list_pw, if (runas_matches_pw(nss->parse_tree, cs, list_pw) == DENY)
cs->runasuserlist) == DENY) {
continue; continue;
} if (root_pw == NULL || runas_matches_pw(nss->parse_tree,
if (root_pw == NULL || userlist_matches(nss->parse_tree, cs, root_pw) != ALLOW) {
root_pw, cs->runasuserlist) != ALLOW) {
continue; continue;
} }
if (cmnd_matches(nss->parse_tree, cs->cmnd, cs->runchroot, if (cmnd_matches(nss->parse_tree, cs->cmnd, cs->runchroot,