[PATCH] netlink: allocate group bitmaps dynamically

Johannes Berg
2007-07-03T11:53:55Z

Allow changing the number of groups for a netlink family
after it has been created.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

---
include/linux/netlink.h | 1
net/netlink/af_netlink.c | 61 +++++++++++++++++++++++++++++++++++------------
2 files changed, 47 insertions(+), 15 deletions(-)

--- wireless-dev.orig/net/netlink/af_netlink.c 2007-07-03 00:10:31.617889695 +0200
+++ wireless-dev/net/netlink/af_netlink.c 2007-07-03 00:31:30.267889695 +0200
@@ -316,8 +316,11 @@ netlink_update_listeners(struct sock *sk

for (i = 0; i < NLGRPSZ(tbl->groups)/sizeof(unsigned long); i++) {
mask = 0;
- sk_for_each_bound(sk, node, &tbl->mc_list)
- mask |= nlk_sk(sk)->groups[i];
+ sk_for_each_bound(sk, node, &tbl->mc_list) {
+ if (nlk_sk(sk)->ngroups >=
+ (i + 1) * sizeof(unsigned long))
+ mask |= nlk_sk(sk)->groups[i];
+ }
tbl->listeners[i] = mask;
}
/* this function is only called with the netlink table "grabbed", which
@@ -555,10 +558,11 @@ netlink_update_subscriptions(struct sock
nlk->subscriptions = subscriptions;
}

-static int netlink_alloc_groups(struct sock *sk)
+static int netlink_realloc_groups(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
unsigned int groups;
+ unsigned long *new_groups;
int err = 0;

netlink_lock_table();
@@ -570,9 +574,15 @@ static int netlink_alloc_groups(struct s
if (err)
return err;

- nlk->groups = kzalloc(NLGRPSZ(groups), GFP_KERNEL);
- if (nlk->groups == NULL)
+ if (nlk->ngroups >= groups)
+ return 0;
+
+ new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_KERNEL);
+ if (new_groups == NULL)
return -ENOMEM;
+ memset((char*)new_groups + NLGRPSZ(nlk->ngroups), 0,
+ NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups));
+ nlk->groups = new_groups;
nlk->ngroups = groups;
return 0;
}
@@ -591,11 +601,9 @@ static int netlink_bind(struct socket *s
if (nladdr->nl_groups) {
if (!netlink_capable(sock, NL_NONROOT_RECV))
return -EPERM;
- if (nlk->groups == NULL) {
- err = netlink_alloc_groups(sk);
- if (err)
- return err;
- }
+ err = netlink_realloc_groups(sk);
+ if (err)
+ return err;
}

if (nlk->pid) {
@@ -1041,11 +1049,9 @@ static int netlink_setsockopt(struct soc

if (!netlink_capable(sock, NL_NONROOT_RECV))
return -EPERM;
- if (nlk->groups == NULL) {
- err = netlink_alloc_groups(sk);
- if (err)
- return err;
- }
+ err = netlink_realloc_groups(sk);
+ if (err)
+ return err;
if (!val || val - 1 >= nlk->ngroups)
return -EINVAL;
netlink_table_grab();
@@ -1332,6 +1338,31 @@ out_sock_release:
return NULL;
}

+int netlink_change_ngroups(int unit, unsigned int groups)
+{
+ unsigned long *listeners;
+ int err = 0;
+
+ netlink_table_grab();
+ if (NLGRPSZ(nl_table[unit].groups) < NLGRPSZ(groups)) {
+ listeners = krealloc(nl_table[unit].listeners,
+ NLGRPSZ(groups), GFP_KERNEL);
+ if (!listeners) {
+ err = -ENOMEM;
+ goto out_ungrab;
+ }
+ memset((char*) listeners + NLGRPSZ(nl_table[unit].groups),
+ 0, NLGRPSZ(groups) - NLGRPSZ(nl_table[unit].groups));
+ nl_table[unit].listeners = listeners;
+ }
+ nl_table[unit].groups = groups;
+
+ out_ungrab:
+ netlink_table_ungrab();
+ return err;
+}
+EXPORT_SYMBOL(netlink_change_ngroups);
+
void netlink_set_nonroot(int protocol, unsigned int flags)
{
if ((unsigned int)protocol < MAX_LINKS)
--- wireless-dev.orig/include/linux/netlink.h 2007-07-03 00:09:13.047889695 +0200
+++ wireless-dev/include/linux/netlink.h 2007-07-03 00:31:30.267889695 +0200
@@ -161,6 +161,7 @@ extern struct sock *netlink_kernel_creat
void (*input)(struct sock *sk, int len),
struct mutex *cb_mutex,
struct module *module);
+extern int netlink_change_ngroups(int unit, unsigned int groups);
extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);
extern int netlink_has_listeners(struct sock *sk, unsigned int group);
extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 pid, int nonblock);