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ipv4,ipv6: grab rtnl before locking the socket
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There are some setsockopt operations in ipv4 and ipv6 that are grabbing
rtnl after having grabbed the socket lock. Yet this makes it impossible
to do operations that have to lock the socket when already within a rtnl
protected scope, like ndo dev_open and dev_stop.

We normally take coarse grained locks first but setsockopt inverted that.

So this patch invert the lock logic for these operations and makes
setsockopt grab rtnl if it will be needed prior to grabbing socket lock.

Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Marcelo Ricardo Leitner authored and David S. Miller committed Mar 19, 2015
1 parent fdf9ef8 commit baf606d
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Showing 2 changed files with 52 additions and 14 deletions.
31 changes: 25 additions & 6 deletions net/ipv4/ip_sockglue.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -536,12 +536,25 @@ int ip_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
* Socket option code for IP. This is the end of the line after any
* TCP,UDP etc options on an IP socket.
*/
static bool setsockopt_needs_rtnl(int optname)
{
switch (optname) {
case IP_ADD_MEMBERSHIP:
case IP_ADD_SOURCE_MEMBERSHIP:
case IP_DROP_MEMBERSHIP:
case MCAST_JOIN_GROUP:
case MCAST_LEAVE_GROUP:
return true;
}
return false;
}

static int do_ip_setsockopt(struct sock *sk, int level,
int optname, char __user *optval, unsigned int optlen)
{
struct inet_sock *inet = inet_sk(sk);
int val = 0, err;
bool needs_rtnl = setsockopt_needs_rtnl(optname);

switch (optname) {
case IP_PKTINFO:
Expand Down Expand Up @@ -584,6 +597,8 @@ static int do_ip_setsockopt(struct sock *sk, int level,
return ip_mroute_setsockopt(sk, optname, optval, optlen);

err = 0;
if (needs_rtnl)
rtnl_lock();
lock_sock(sk);

switch (optname) {
Expand Down Expand Up @@ -846,9 +861,9 @@ static int do_ip_setsockopt(struct sock *sk, int level,
}

if (optname == IP_ADD_MEMBERSHIP)
err = ip_mc_join_group(sk, &mreq);
err = __ip_mc_join_group(sk, &mreq);
else
err = ip_mc_leave_group(sk, &mreq);
err = __ip_mc_leave_group(sk, &mreq);
break;
}
case IP_MSFILTER:
Expand Down Expand Up @@ -913,7 +928,7 @@ static int do_ip_setsockopt(struct sock *sk, int level,
mreq.imr_multiaddr.s_addr = mreqs.imr_multiaddr;
mreq.imr_address.s_addr = mreqs.imr_interface;
mreq.imr_ifindex = 0;
err = ip_mc_join_group(sk, &mreq);
err = __ip_mc_join_group(sk, &mreq);
if (err && err != -EADDRINUSE)
break;
omode = MCAST_INCLUDE;
Expand Down Expand Up @@ -945,9 +960,9 @@ static int do_ip_setsockopt(struct sock *sk, int level,
mreq.imr_ifindex = greq.gr_interface;

if (optname == MCAST_JOIN_GROUP)
err = ip_mc_join_group(sk, &mreq);
err = __ip_mc_join_group(sk, &mreq);
else
err = ip_mc_leave_group(sk, &mreq);
err = __ip_mc_leave_group(sk, &mreq);
break;
}
case MCAST_JOIN_SOURCE_GROUP:
Expand Down Expand Up @@ -990,7 +1005,7 @@ static int do_ip_setsockopt(struct sock *sk, int level,
mreq.imr_multiaddr = psin->sin_addr;
mreq.imr_address.s_addr = 0;
mreq.imr_ifindex = greqs.gsr_interface;
err = ip_mc_join_group(sk, &mreq);
err = __ip_mc_join_group(sk, &mreq);
if (err && err != -EADDRINUSE)
break;
greqs.gsr_interface = mreq.imr_ifindex;
Expand Down Expand Up @@ -1118,10 +1133,14 @@ static int do_ip_setsockopt(struct sock *sk, int level,
break;
}
release_sock(sk);
if (needs_rtnl)
rtnl_unlock();
return err;

e_inval:
release_sock(sk);
if (needs_rtnl)
rtnl_unlock();
return -EINVAL;
}

Expand Down
35 changes: 27 additions & 8 deletions net/ipv6/ipv6_sockglue.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -117,13 +117,26 @@ struct ipv6_txoptions *ipv6_update_options(struct sock *sk,
return opt;
}

static bool setsockopt_needs_rtnl(int optname)
{
switch (optname) {
case IPV6_ADD_MEMBERSHIP:
case IPV6_DROP_MEMBERSHIP:
case MCAST_JOIN_GROUP:
case MCAST_LEAVE_GROUP:
return true;
}
return false;
}

static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
char __user *optval, unsigned int optlen)
{
struct ipv6_pinfo *np = inet6_sk(sk);
struct net *net = sock_net(sk);
int val, valbool;
int retv = -ENOPROTOOPT;
bool needs_rtnl = setsockopt_needs_rtnl(optname);

if (optval == NULL)
val = 0;
Expand All @@ -140,6 +153,8 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
if (ip6_mroute_opt(optname))
return ip6_mroute_setsockopt(sk, optname, optval, optlen);

if (needs_rtnl)
rtnl_lock();
lock_sock(sk);

switch (optname) {
Expand Down Expand Up @@ -582,9 +597,9 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
break;

if (optname == IPV6_ADD_MEMBERSHIP)
retv = ipv6_sock_mc_join(sk, mreq.ipv6mr_ifindex, &mreq.ipv6mr_multiaddr);
retv = __ipv6_sock_mc_join(sk, mreq.ipv6mr_ifindex, &mreq.ipv6mr_multiaddr);
else
retv = ipv6_sock_mc_drop(sk, mreq.ipv6mr_ifindex, &mreq.ipv6mr_multiaddr);
retv = __ipv6_sock_mc_drop(sk, mreq.ipv6mr_ifindex, &mreq.ipv6mr_multiaddr);
break;
}
case IPV6_JOIN_ANYCAST:
Expand Down Expand Up @@ -623,11 +638,11 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
}
psin6 = (struct sockaddr_in6 *)&greq.gr_group;
if (optname == MCAST_JOIN_GROUP)
retv = ipv6_sock_mc_join(sk, greq.gr_interface,
&psin6->sin6_addr);
retv = __ipv6_sock_mc_join(sk, greq.gr_interface,
&psin6->sin6_addr);
else
retv = ipv6_sock_mc_drop(sk, greq.gr_interface,
&psin6->sin6_addr);
retv = __ipv6_sock_mc_drop(sk, greq.gr_interface,
&psin6->sin6_addr);
break;
}
case MCAST_JOIN_SOURCE_GROUP:
Expand Down Expand Up @@ -659,8 +674,8 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
struct sockaddr_in6 *psin6;

psin6 = (struct sockaddr_in6 *)&greqs.gsr_group;
retv = ipv6_sock_mc_join(sk, greqs.gsr_interface,
&psin6->sin6_addr);
retv = __ipv6_sock_mc_join(sk, greqs.gsr_interface,
&psin6->sin6_addr);
/* prior join w/ different source is ok */
if (retv && retv != -EADDRINUSE)
break;
Expand Down Expand Up @@ -837,11 +852,15 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
}

release_sock(sk);
if (needs_rtnl)
rtnl_unlock();

return retv;

e_inval:
release_sock(sk);
if (needs_rtnl)
rtnl_unlock();
return -EINVAL;
}

Expand Down

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