Author: des
Date: Tue Nov 25 09:47:15 2014
New Revision: 275020
URL: https://svnweb.freebsd.org/changeset/base/275020
Log:
The fallback flag in nsdispatch prevents the fallback implementation of
getgroupmembership() from invoking the correct backend in the compat case.
Replace it with a nesting depth counter so it only blocks one level (the
first is the group -> group_compat translation, the second is the actual
backend). This is one of two bugs that break getgrouplist() in the compat
case, the second being that the backend's own getgroupmembership() method
is ignored. Unfortunately, that is not easily fixable without a redesign
of our nss implementation (which is also needed to implement the +@group
syntax in /etc/passwd).
PR: 190055
MFC after: 1 week
Modified:
head/lib/libc/net/nsdispatch.c
Modified: head/lib/libc/net/nsdispatch.c
==============================================================================
--- head/lib/libc/net/nsdispatch.c Tue Nov 25 08:39:46 2014
(r275019)
+++ head/lib/libc/net/nsdispatch.c Tue Nov 25 09:47:15 2014
(r275020)
@@ -132,14 +132,17 @@ static void
*nss_cache_cycle_preventio
#endif
/*
- * When this is set to 1, nsdispatch won't use nsswitch.conf
- * but will consult the 'defaults' source list only.
- * NOTE: nested fallbacks (when nsdispatch calls fallback functions,
- * which in turn calls nsdispatch, which should call fallback
- * function) are not supported
+ * We keep track of nsdispatch() nesting depth in dispatch_depth. When a
+ * fallback method is invoked from nsdispatch(), we temporarily set
+ * fallback_depth to the current dispatch depth plus one. Subsequent
+ * calls at that exact depth will run in fallback mode (restricted to the
+ * same source as the call that was handled by the fallback method), while
+ * calls below that depth will be handled normally, allowing fallback
+ * methods to perform arbitrary lookups.
*/
struct fb_state {
- int fb_dispatch;
+ int dispatch_depth;
+ int fallback_depth;
};
static void fb_endstate(void *);
NSS_TLS_HANDLING(fb);
@@ -613,6 +616,7 @@ _nsdispatch(void *retval, const ns_dtab
void *mdata;
int isthreaded, serrno, i, result, srclistsize;
struct fb_state *st;
+ int saved_depth;
#ifdef NS_CACHING
nss_cache_data cache_data;
@@ -644,7 +648,8 @@ _nsdispatch(void *retval, const ns_dtab
result = NS_UNAVAIL;
goto fin;
}
- if (st->fb_dispatch == 0) {
+ ++st->dispatch_depth;
+ if (st->dispatch_depth > st->fallback_depth) {
dbt = vector_search(&database, _nsmap, _nsmapsize,
sizeof(*_nsmap),
string_compare);
fb_method = nss_method_lookup(NSSRC_FALLBACK, database,
@@ -713,12 +718,13 @@ _nsdispatch(void *retval, const ns_dtab
break;
} else {
if (fb_method != NULL) {
- st->fb_dispatch = 1;
+ saved_depth = st->fallback_depth;
+ st->fallback_depth = st->dispatch_depth + 1;
va_start(ap, defaults);
result = fb_method(retval,
(void *)srclist[i].name, ap);
va_end(ap);
- st->fb_dispatch = 0;
+ st->fallback_depth = saved_depth;
} else
nss_log(LOG_DEBUG, "%s, %s, %s, not found, "
"and no fallback provided",
@@ -750,6 +756,7 @@ _nsdispatch(void *retval, const ns_dtab
if (isthreaded)
(void)_pthread_rwlock_unlock(&nss_lock);
+ --st->dispatch_depth;
fin:
errno = serrno;
return (result);
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