From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
Eric Dumazet <edumazet@google.com>,
Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Netdev <netdev@vger.kernel.org>,
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Kernel Hardening <kernel-hardening@lists.openwall.com>
Subject: Re: [PATCH 12/26] netfilter: switch nf_setsockopt to sockptr_t
Date: Mon, 27 Jul 2020 16:16:32 +0000 [thread overview]
Message-ID: <CAHmME9ric=chLJayn7Erve7WBa+qCKn-+Gjri=zqydoY6623aA@mail.gmail.com> (raw)
In-Reply-To: <20200727150601.GA3447@lst.de>
On Mon, Jul 27, 2020 at 5:06 PM Christoph Hellwig <hch@lst.de> wrote:
>
> On Mon, Jul 27, 2020 at 05:03:10PM +0200, Jason A. Donenfeld wrote:
> > Hi Christoph,
> >
> > On Thu, Jul 23, 2020 at 08:08:54AM +0200, Christoph Hellwig wrote:
> > > diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> > > index da933f99b5d517..42befbf12846c0 100644
> > > --- a/net/ipv4/ip_sockglue.c
> > > +++ b/net/ipv4/ip_sockglue.c
> > > @@ -1422,7 +1422,8 @@ int ip_setsockopt(struct sock *sk, int level,
> > > optname != IP_IPSEC_POLICY &&
> > > optname != IP_XFRM_POLICY &&
> > > !ip_mroute_opt(optname))
> > > - err = nf_setsockopt(sk, PF_INET, optname, optval, optlen);
> > > + err = nf_setsockopt(sk, PF_INET, optname, USER_SOCKPTR(optval),
> > > + optlen);
> > > #endif
> > > return err;
> > > }
> > > diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
> > > index 4697d09c98dc3e..f2a9680303d8c0 100644
> > > --- a/net/ipv4/netfilter/ip_tables.c
> > > +++ b/net/ipv4/netfilter/ip_tables.c
> > > @@ -1102,7 +1102,7 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
> > > }
> > >
> > > static int
> > > -do_replace(struct net *net, const void __user *user, unsigned int len)
> > > +do_replace(struct net *net, sockptr_t arg, unsigned int len)
> > > {
> > > int ret;
> > > struct ipt_replace tmp;
> > > @@ -1110,7 +1110,7 @@ do_replace(struct net *net, const void __user *user, unsigned int len)
> > > void *loc_cpu_entry;
> > > struct ipt_entry *iter;
> > >
> > > - if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
> > > + if (copy_from_sockptr(&tmp, arg, sizeof(tmp)) != 0)
> > > return -EFAULT;
> > >
> > > /* overflow check */
> > > @@ -1126,8 +1126,8 @@ do_replace(struct net *net, const void __user *user, unsigned int len)
> > > return -ENOMEM;
> > >
> > > loc_cpu_entry = newinfo->entries;
> > > - if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
> > > - tmp.size) != 0) {
> > > + sockptr_advance(arg, sizeof(tmp));
> > > + if (copy_from_sockptr(loc_cpu_entry, arg, tmp.size) != 0) {
> > > ret = -EFAULT;
> > > goto free_newinfo;
> > > }
> >
> > Something along this path seems to have broken with this patch. An
> > invocation of `iptables -A INPUT -m length --length 1360 -j DROP` now
> > fails, with
> >
> > nf_setsockopt->do_replace->translate_table->check_entry_size_and_hooks:
> > (unsigned char *)e + e->next_offset > limit => TRUE
> >
> > resulting in the whole call chain returning -EINVAL. It bisects back to
> > this commit. This is on net-next.
>
> This is another use o sockptr_advance that Ido already found a problem
> in. I'm looking into this at the moment..
I haven't seen Ido's patch, but it seems clear the issue is that you
want to call `sockptr_advance(&arg, sizeof(tmp))`, and adjust
sockptr_advance to take a pointer.
Slight concern about the whole concept:
Things are defined as
typedef union {
void *kernel;
void __user *user;
} sockptr_t;
static inline bool sockptr_is_kernel(sockptr_t sockptr)
{
return (unsigned long)sockptr.kernel >= TASK_SIZE;
}
So what happens if we have some code like:
sockptr_t sp;
init_user_sockptr(&sp, user_controlled_struct.extra_user_ptr);
sockptr_advance(&sp, user_controlled_struct.some_big_offset);
copy_to_sockptr(&sp, user_controlled_struct.a_few_bytes,
sizeof(user_controlled_struct.a_few_bytes));
With the user controlling some_big_offset, he can convert the user
sockptr into a kernel sockptr, causing the subsequent copy_to_sockptr
to be a vanilla memcpy, after which a security disaster ensues.
Maybe sockptr_advance should have some safety checks and sometimes
return -EFAULT? Or you should always use the implementation where
being a kernel address is an explicit bit of sockptr_t, rather than
being implicit?
next prev parent reply other threads:[~2020-07-27 16:16 UTC|newest]
Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-20 12:47 get rid of the address_space override in setsockopt Christoph Hellwig
2020-07-20 12:47 ` [PATCH 01/24] bpfilter: reject kernel addresses Christoph Hellwig
2020-07-20 12:47 ` [PATCH 02/24] bpfilter: fix up a sparse annotation Christoph Hellwig
2020-07-21 2:40 ` Luc Van Oostenryck
2020-07-21 5:23 ` Christoph Hellwig
2020-07-21 5:28 ` Al Viro
2020-07-20 12:47 ` [PATCH 03/24] net: add a new sockptr_t type Christoph Hellwig
2020-07-20 16:37 ` Eric Biggers
2020-07-20 17:43 ` Christoph Hellwig
2020-07-20 17:55 ` Eric Biggers
2020-07-22 7:56 ` Christoph Hellwig
2020-07-21 9:55 ` David Laight
2020-07-21 10:14 ` David Laight
2020-07-20 12:47 ` [PATCH 04/24] net: switch copy_bpf_fprog_from_user to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 05/24] net: switch sock_setbindtodevice " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 06/24] net: switch sock_set_timeout " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 07/24] " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 08/24] net/xfrm: switch xfrm_user_policy " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 09/24] netfilter: remove the unused user argument to do_update_counters Christoph Hellwig
2020-07-20 12:47 ` [PATCH 10/24] netfilter: switch xt_copy_counters to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 11/24] netfilter: switch nf_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 12/24] bpfilter: switch bpfilter_ip_set_sockopt " Christoph Hellwig
2020-07-21 8:36 ` David Laight
2020-07-22 8:00 ` 'Christoph Hellwig'
2020-07-22 8:01 ` 'Christoph Hellwig'
2020-07-20 12:47 ` [PATCH 13/24] net/ipv4: switch ip_mroute_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 14/24] net/ipv4: merge ip_options_get and ip_options_get_from_user Christoph Hellwig
2020-07-20 12:47 ` [PATCH 15/24] net/ipv4: switch do_ip_setsockopt to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 16/24] net/ipv6: switch ip6_mroute_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 17/24] net/ipv6: split up ipv6_flowlabel_opt Christoph Hellwig
2020-07-20 12:47 ` [PATCH 18/24] net/ipv6: switch ipv6_flowlabel_opt to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 19/24] net/ipv6: factor out a ipv6_set_opt_hdr helper Christoph Hellwig
2020-07-20 12:47 ` [PATCH 20/24] net/ipv6: switch do_ipv6_setsockopt to sockptr_t Christoph Hellwig
2020-07-20 12:47 ` [PATCH 21/24] net/udp: switch udp_lib_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 22/24] net/tcp: switch ->md5_parse " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 23/24] net/tcp: switch do_tcp_setsockopt " Christoph Hellwig
2020-07-20 12:47 ` [PATCH 24/24] net: pass a sockptr_t into ->setsockopt Christoph Hellwig
2020-07-20 14:19 ` Stefan Schmidt
2020-07-20 23:20 ` David Miller
2020-07-22 8:26 ` [MPTCP] " Matthieu Baerts
2020-07-20 16:38 ` get rid of the address_space override in setsockopt Eric Biggers
2020-07-20 17:43 ` Christoph Hellwig
2020-07-20 20:47 ` Alexei Starovoitov
2020-07-22 7:56 ` Christoph Hellwig
2020-07-22 17:09 ` Alexei Starovoitov
2020-07-21 9:38 ` David Laight
2020-07-22 8:06 ` 'Christoph Hellwig'
2020-07-22 8:21 ` David Laight
2020-07-21 10:26 ` David Laight
2020-07-22 8:07 ` 'Christoph Hellwig'
2020-07-23 6:08 ` get rid of the address_space override in setsockopt v2 Christoph Hellwig
2020-07-23 6:08 ` [PATCH 01/26] bpfilter: fix up a sparse annotation Christoph Hellwig
2020-07-23 11:14 ` Luc Van Oostenryck
2020-07-23 6:08 ` [PATCH 02/26] net/bpfilter: split __bpfilter_process_sockopt Christoph Hellwig
2020-07-23 6:08 ` [PATCH 03/26] bpfilter: reject kernel addresses Christoph Hellwig
2020-07-23 14:42 ` David Laight
2020-07-23 14:44 ` 'Christoph Hellwig'
2020-07-23 14:56 ` David Laight
2020-07-23 6:08 ` [PATCH 04/26] net: add a new sockptr_t type Christoph Hellwig
2020-07-23 15:40 ` Jan Engelhardt
2020-07-23 16:40 ` Eric Dumazet
2020-07-23 16:44 ` Christoph Hellwig
2020-07-23 6:08 ` [PATCH 05/26] net: switch copy_bpf_fprog_from_user to sockptr_t Christoph Hellwig
2020-07-23 6:08 ` [PATCH 06/26] net: switch sock_setbindtodevice " Christoph Hellwig
2020-07-23 6:08 ` [PATCH 07/26] net: switch sock_set_timeout " Christoph Hellwig
2020-07-23 6:08 ` [PATCH 08/26] " Christoph Hellwig
2020-07-23 8:39 ` [MPTCP] " Matthieu Baerts
2020-07-23 6:08 ` [PATCH 09/26] net/xfrm: switch xfrm_user_policy " Christoph Hellwig
2020-07-23 6:08 ` [PATCH 10/26] netfilter: remove the unused user argument to do_update_counters Christoph Hellwig
2020-07-23 6:08 ` [PATCH 11/26] netfilter: switch xt_copy_counters to sockptr_t Christoph Hellwig
2020-07-23 6:08 ` [PATCH 12/26] netfilter: switch nf_setsockopt " Christoph Hellwig
2020-07-27 15:03 ` Jason A. Donenfeld
2020-07-27 15:06 ` Christoph Hellwig
2020-07-27 16:16 ` Jason A. Donenfeld [this message]
2020-07-27 16:23 ` Christoph Hellwig
2020-07-28 8:07 ` David Laight
2020-07-28 8:17 ` Jason A. Donenfeld
2020-07-27 16:16 ` Christoph Hellwig
2020-07-27 16:21 ` Jason A. Donenfeld
2020-07-23 6:08 ` [PATCH 13/26] bpfilter: switch bpfilter_ip_set_sockopt " Christoph Hellwig
2020-07-23 11:16 ` David Laight
2020-07-23 11:44 ` 'Christoph Hellwig'
2020-07-23 6:08 ` [PATCH 14/26] net/ipv4: switch ip_mroute_setsockopt " Christoph Hellwig
2020-07-23 6:08 ` [PATCH 15/26] net/ipv4: merge ip_options_get and ip_options_get_from_user Christoph Hellwig
2020-07-23 6:08 ` [PATCH 16/26] net/ipv4: switch do_ip_setsockopt to sockptr_t Christoph Hellwig
2020-07-23 6:08 ` [PATCH 17/26] net/ipv6: switch ip6_mroute_setsockopt " Christoph Hellwig
2020-07-23 6:09 ` [PATCH 18/26] net/ipv6: split up ipv6_flowlabel_opt Christoph Hellwig
2020-07-23 6:09 ` [PATCH 19/26] net/ipv6: switch ipv6_flowlabel_opt to sockptr_t Christoph Hellwig
2020-07-27 12:15 ` Ido Schimmel
2020-07-27 13:00 ` Christoph Hellwig
2020-07-27 13:33 ` Ido Schimmel
2020-07-27 16:15 ` Christoph Hellwig
2020-07-27 18:22 ` Ido Schimmel
2020-07-27 13:24 ` David Laight
2020-07-23 6:09 ` [PATCH 20/26] net/ipv6: factor out a ipv6_set_opt_hdr helper Christoph Hellwig
2020-07-23 6:09 ` [PATCH 21/26] net/ipv6: switch do_ipv6_setsockopt to sockptr_t Christoph Hellwig
2020-07-23 6:09 ` [PATCH 22/26] net/udp: switch udp_lib_setsockopt " Christoph Hellwig
2020-07-23 6:09 ` [PATCH 23/26] net/tcp: switch ->md5_parse " Christoph Hellwig
2020-07-23 6:09 ` [PATCH 24/26] net/tcp: switch do_tcp_setsockopt " Christoph Hellwig
2020-07-23 6:09 ` [PATCH 25/26] net: pass a sockptr_t into ->setsockopt Christoph Hellwig
2020-07-23 8:39 ` [MPTCP] " Matthieu Baerts
2020-08-06 22:21 ` Eric Dumazet
2020-08-07 7:21 ` Christoph Hellwig
2020-08-07 9:18 ` David Laight
2020-08-07 18:29 ` Eric Dumazet
2020-08-08 13:54 ` David Laight
2020-07-23 6:09 ` [PATCH 26/26] net: optimize the sockptr_t for unified kernel/user address spaces Christoph Hellwig
2020-07-24 22:43 ` get rid of the address_space override in setsockopt v2 David Miller
2020-07-26 7:03 ` Christoph Hellwig
2020-07-26 7:08 ` Andreas Schwab
2020-07-26 7:46 ` David Miller
2020-07-27 9:51 ` David Laight
2020-07-27 13:48 ` Al Viro
2020-07-27 14:09 ` David Laight
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