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ipv4: do compat setsockopt for MCAST_MSFILTER directly

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Parallel to what the native setsockopt() does, except that unlike
the native setsockopt() we do not use memdup_user() - we want
the sockaddr_storage fields properly aligned, so we allocate
4 bytes more and copy compat_group_filter at the offset 4,
which yields the proper alignments.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2020-03-30 15:39:43 -04:00
parent e986d4dabc
commit 2e04172875
1 changed files with 47 additions and 1 deletions
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48
net/ipv4/ip_sockglue.c
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@ -1286,9 +1286,55 @@ int compat_ip_setsockopt(struct sock *sk, int level, int optname,
case MCAST_LEAVE_SOURCE_GROUP:
case MCAST_BLOCK_SOURCE:
case MCAST_UNBLOCK_SOURCE:
case MCAST_MSFILTER:
return compat_mc_setsockopt(sk, level, optname, optval, optlen,
ip_setsockopt);
case MCAST_MSFILTER:
{
const int size0 = offsetof(struct compat_group_filter, gf_slist);
struct compat_group_filter *gf32;
void *p;
int n;
if (optlen < size0)
return -EINVAL;
if (optlen > sysctl_optmem_max - 4)
return -ENOBUFS;
p = kmalloc(optlen + 4, GFP_KERNEL);
if (!p)
return -ENOMEM;
gf32 = p + 4; /* we want ->gf_group and ->gf_slist aligned */
if (copy_from_user(gf32, optval, optlen)) {
err = -EFAULT;
goto mc_msf_out;
}
n = gf32->gf_numsrc;
/* numsrc >= (4G-140)/128 overflow in 32 bits */
if (n >= 0x1ffffff) {
err = -ENOBUFS;
goto mc_msf_out;
}
if (offsetof(struct compat_group_filter, gf_slist[n]) > optlen) {
err = -EINVAL;
goto mc_msf_out;
}
rtnl_lock();
lock_sock(sk);
/* numsrc >= (4G-140)/128 overflow in 32 bits */
if (n > sock_net(sk)->ipv4.sysctl_igmp_max_msf)
err = -ENOBUFS;
else
err = set_mcast_msfilter(sk, gf32->gf_interface,
n, gf32->gf_fmode,
&gf32->gf_group, gf32->gf_slist);
release_sock(sk);
rtnl_unlock();
mc_msf_out:
kfree(p);
return err;
}
}
err = do_ip_setsockopt(sk, level, optname, optval, optlen);