Access to the nlk group should be protected by netlink_lock_table() like
commit <f773608026ee> ("netlink: access nlk groups safely in netlink bind
and getname"), otherwise there will be potential race conditions.
Signed-off-by: nai lin <[email protected]>
---
net/netlink/af_netlink.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 4ed8ffd58ff3..61ad81fb80f5 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2693,6 +2693,7 @@ static int netlink_native_seq_show(struct seq_file *seq, void *v)
struct sock *s = v;
struct netlink_sock *nlk = nlk_sk(s);
+ netlink_lock_table();
seq_printf(seq, "%pK %-3d %-10u %08x %-8d %-8d %-5d %-8d %-8u %-8lu\n",
s,
s->sk_protocol,
@@ -2705,7 +2706,7 @@ static int netlink_native_seq_show(struct seq_file *seq, void *v)
atomic_read(&s->sk_drops),
sock_i_ino(s)
);
-
+ netlink_unlock_table();
}
return 0;
}
--
2.25.1
On Wed, Jan 17, 2024 at 9:38 AM nai lin <[email protected]> wrote:
>
> Access to the nlk group should be protected by netlink_lock_table() like
> commit <f773608026ee> ("netlink: access nlk groups safely in netlink bind
> and getname"), otherwise there will be potential race conditions.
>
> Signed-off-by: nai lin <[email protected]>
OK, I think you forgot to include this tag I suggested earlier to you.
Fixes: e341694e3eb5 ("netlink: Convert netlink_lookup() to use RCU
protected hash table")
> ---
> net/netlink/af_netlink.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
> index 4ed8ffd58ff3..61ad81fb80f5 100644
> --- a/net/netlink/af_netlink.c
> +++ b/net/netlink/af_netlink.c
> @@ -2693,6 +2693,7 @@ static int netlink_native_seq_show(struct seq_file *seq, void *v)
> struct sock *s = v;
> struct netlink_sock *nlk = nlk_sk(s);
>
> + netlink_lock_table();
netlink_lock_table() is heavy weight, appropriate for contexts where
we might sleep.
We could instead use a helper to acquire the lock for a very small period.
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 4ed8ffd58ff375f3fa9f262e6f3b4d1a1aaf2731..c50ca0f5adfb9691e6df37b4ac518b95c2d7908f
100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1136,6 +1136,18 @@ static int netlink_connect(struct socket *sock,
struct sockaddr *addr,
return err;
}
+static u32 netlink_get_groups_mask(const struct netlink_sock *nlk)
+{
+ unsigned long flags;
+ u32 res;
+
+ read_lock_irqsave(&nl_table_lock, flags);
+ res = nlk->groups ? nlk->groups[0] : 0;
+ read_unlock_irqrestore(&nl_table_lock, flags);
+
+ return res;
+}
+
static int netlink_getname(struct socket *sock, struct sockaddr *addr,
int peer)
{
@@ -1153,9 +1165,7 @@ static int netlink_getname(struct socket *sock,
struct sockaddr *addr,
} else {
/* Paired with WRITE_ONCE() in netlink_insert() */
nladdr->nl_pid = READ_ONCE(nlk->portid);
- netlink_lock_table();
- nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
- netlink_unlock_table();
+ nladdr->nl_groups = netlink_get_groups_mask(nlk);
}
return sizeof(*nladdr);
}
@@ -2697,7 +2707,7 @@ static int netlink_native_seq_show(struct
seq_file *seq, void *v)
s,
s->sk_protocol,
nlk->portid,
- nlk->groups ? (u32)nlk->groups[0] : 0,
+ netlink_get_groups_mask(nlk),
sk_rmem_alloc_get(s),
sk_wmem_alloc_get(s),
READ_ONCE(nlk->cb_running),
On Wed, Jan 17, 2024 at 11:28:24AM +0100, Eric Dumazet wrote:
> On Wed, Jan 17, 2024 at 9:38 AM nai lin <[email protected]> wrote:
> >
> > Access to the nlk group should be protected by netlink_lock_table() like
> > commit <f773608026ee> ("netlink: access nlk groups safely in netlink bind
> > and getname"), otherwise there will be potential race conditions.
> >
> > Signed-off-by: nai lin <[email protected]>
>
> OK, I think you forgot to include this tag I suggested earlier to you.
>
> Fixes: e341694e3eb5 ("netlink: Convert netlink_lookup() to use RCU
> protected hash table")
>
Sorry I forgot to include fix tag, thank you for pointing out my problem
and thank you very much for your work.
> > ---
> > net/netlink/af_netlink.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
> > index 4ed8ffd58ff3..61ad81fb80f5 100644
> > --- a/net/netlink/af_netlink.c
> > +++ b/net/netlink/af_netlink.c
> > @@ -2693,6 +2693,7 @@ static int netlink_native_seq_show(struct seq_file *seq, void *v)
> > struct sock *s = v;
> > struct netlink_sock *nlk = nlk_sk(s);
> >
> > + netlink_lock_table();
>
> netlink_lock_table() is heavy weight, appropriate for contexts where
> we might sleep.
>
> We could instead use a helper to acquire the lock for a very small period.
>
> diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
> index 4ed8ffd58ff375f3fa9f262e6f3b4d1a1aaf2731..c50ca0f5adfb9691e6df37b4ac518b95c2d7908f
> 100644
> --- a/net/netlink/af_netlink.c
> +++ b/net/netlink/af_netlink.c
> @@ -1136,6 +1136,18 @@ static int netlink_connect(struct socket *sock,
> struct sockaddr *addr,
> return err;
> }
>
> +static u32 netlink_get_groups_mask(const struct netlink_sock *nlk)
> +{
> + unsigned long flags;
> + u32 res;
> +
> + read_lock_irqsave(&nl_table_lock, flags);
> + res = nlk->groups ? nlk->groups[0] : 0;
> + read_unlock_irqrestore(&nl_table_lock, flags);
> +
> + return res;
> +}
> +
> static int netlink_getname(struct socket *sock, struct sockaddr *addr,
> int peer)
> {
> @@ -1153,9 +1165,7 @@ static int netlink_getname(struct socket *sock,
> struct sockaddr *addr,
> } else {
> /* Paired with WRITE_ONCE() in netlink_insert() */
> nladdr->nl_pid = READ_ONCE(nlk->portid);
> - netlink_lock_table();
> - nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
> - netlink_unlock_table();
> + nladdr->nl_groups = netlink_get_groups_mask(nlk);
> }
> return sizeof(*nladdr);
> }
> @@ -2697,7 +2707,7 @@ static int netlink_native_seq_show(struct
> seq_file *seq, void *v)
> s,
> s->sk_protocol,
> nlk->portid,
> - nlk->groups ? (u32)nlk->groups[0] : 0,
> + netlink_get_groups_mask(nlk),
> sk_rmem_alloc_get(s),
> sk_wmem_alloc_get(s),
> READ_ONCE(nlk->cb_running),