[RFC PATCH] Teach auth_unix cache to check network namespace in comparisons

[Rob Landley <rlandley@parallels.com>]

This patch samples current->nsproxy->net_ns in ip_map_parse().
As far as I can tell this function is currently only called from
cache_write_procfs() and cache_write_pipefs() (via cache_write()
and cache_downcall()), meaning we should always have a relevant
process context.  (The buf argument is __user annotated through
cache_do_downcall()).

Does this sound like the right way to do it, or should I try to
add a struct net * argument to cache_parse(), or...?

Here's the patch I have.

From: Rob Landley <rlandley@parallels.com>

Teach the auth_unix cache to check network namespace when comparing addresses.

Signed-off-by: Rob Landley <rlandley@parallels.com>
---

 net/sunrpc/svcauth_unix.c |   21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
index 30916b0..63a2fa7 100644
--- a/net/sunrpc/svcauth_unix.c
+++ b/net/sunrpc/svcauth_unix.c
@@ -14,6 +14,7 @@
 #include <net/sock.h>
 #include <net/ipv6.h>
 #include <linux/kernel.h>
+#include <linux/user_namespace.h>
 #define RPCDBG_FACILITY	RPCDBG_AUTH
 
 #include <linux/sunrpc/clnt.h>
@@ -94,6 +95,7 @@ struct ip_map {
 	struct cache_head	h;
 	char			m_class[8]; /* e.g. "nfsd" */
 	struct in6_addr		m_addr;
+	struct net		*m_net;
 	struct unix_domain	*m_client;
 #ifdef CONFIG_NFSD_DEPRECATED
 	int			m_add_change;
@@ -134,6 +136,7 @@ static int ip_map_match(struct cache_head *corig, struct cache_head *cnew)
 	struct ip_map *orig = container_of(corig, struct ip_map, h);
 	struct ip_map *new = container_of(cnew, struct ip_map, h);
 	return strcmp(orig->m_class, new->m_class) == 0 &&
+	       net_eq(orig->m_net, new->m_net) &&
 	       ipv6_addr_equal(&orig->m_addr, &new->m_addr);
 }
 static void ip_map_init(struct cache_head *cnew, struct cache_head *citem)
@@ -142,6 +145,7 @@ static void ip_map_init(struct cache_head *cnew, struct cache_head *citem)
 	struct ip_map *item = container_of(citem, struct ip_map, h);
 
 	strcpy(new->m_class, item->m_class);
+	new->m_net = item->m_net;
 	ipv6_addr_copy(&new->m_addr, &item->m_addr);
 }
 static void update(struct cache_head *cnew, struct cache_head *citem)
@@ -186,7 +190,7 @@ static int ip_map_upcall(struct cache_detail *cd, struct cache_head *h)
 	return sunrpc_cache_pipe_upcall(cd, h, ip_map_request);
 }
 
-static struct ip_map *__ip_map_lookup(struct cache_detail *cd, char *class, struct in6_addr *addr);
+static struct ip_map *__ip_map_lookup(struct cache_detail *cd, struct net *net, char *class, struct in6_addr *addr);
 static int __ip_map_update(struct cache_detail *cd, struct ip_map *ipm, struct unix_domain *udom, time_t expiry);
 
 static int ip_map_parse(struct cache_detail *cd,
@@ -256,7 +260,8 @@ static int ip_map_parse(struct cache_detail *cd,
 		dom = NULL;
 
 	/* IPv6 scope IDs are ignored for now */
-	ipmp = __ip_map_lookup(cd, class, &sin6.sin6_addr);
+	ipmp = __ip_map_lookup(cd, current->nsproxy->net_ns, class,
+			       &sin6.sin6_addr);
 	if (ipmp) {
 		err = __ip_map_update(cd, ipmp,
 			     container_of(dom, struct unix_domain, h),
@@ -301,13 +306,14 @@ static int ip_map_show(struct seq_file *m,
 }
 
 
-static struct ip_map *__ip_map_lookup(struct cache_detail *cd, char *class,
-		struct in6_addr *addr)
+static struct ip_map *__ip_map_lookup(struct cache_detail *cd, struct net *net,
+		char *class, struct in6_addr *addr)
 {
 	struct ip_map ip;
 	struct cache_head *ch;
 
 	strcpy(ip.m_class, class);
+	ip.m_net = net;
 	ipv6_addr_copy(&ip.m_addr, addr);
 	ch = sunrpc_cache_lookup(cd, &ip.h,
 				 hash_str(class, IP_HASHBITS) ^
@@ -325,7 +331,7 @@ static inline struct ip_map *ip_map_lookup(struct net *net, char *class,
 	struct sunrpc_net *sn;
 
 	sn = net_generic(net, sunrpc_net_id);
-	return __ip_map_lookup(sn->ip_map_cache, class, addr);
+	return __ip_map_lookup(sn->ip_map_cache, net, class, addr);
 }
 
 static int __ip_map_update(struct cache_detail *cd, struct ip_map *ipm,
@@ -748,8 +754,9 @@ svcauth_unix_set_client(struct svc_rqst *rqstp)
 
 	ipm = ip_map_cached_get(xprt);
 	if (ipm == NULL)
-		ipm = __ip_map_lookup(sn->ip_map_cache, rqstp->rq_server->sv_program->pg_class,
-				    &sin6->sin6_addr);
+		ipm = __ip_map_lookup(sn->ip_map_cache, net,
+				      rqstp->rq_server->sv_program->pg_class,
+				      &sin6->sin6_addr);
 
 	if (ipm == NULL)
 		return SVC_DENIED;