* Re: possible deadlock in perf_event_detach_bpf_prog
From: Y Song @ 2018-04-08 15:56 UTC (permalink / raw)
To: Daniel Borkmann
Cc: syzbot, Alexei Starovoitov, linux-kernel, mingo, netdev, rostedt,
syzkaller-bugs
In-Reply-To: <439cb956-9f4d-b972-07f2-40080b25ecbf@iogearbox.net>
On Thu, Mar 29, 2018 at 2:18 PM, Daniel Borkmann <daniel@iogearbox.net> wrote:
> On 03/29/2018 11:04 PM, syzbot wrote:
>> Hello,
>>
>> syzbot hit the following crash on upstream commit
>> 3eb2ce825ea1ad89d20f7a3b5780df850e4be274 (Sun Mar 25 22:44:30 2018 +0000)
>> Linux 4.16-rc7
>> syzbot dashboard link: https://syzkaller.appspot.com/bug?extid=dc5ca0e4c9bfafaf2bae
>>
>> Unfortunately, I don't have any reproducer for this crash yet.
>> Raw console output: https://syzkaller.appspot.com/x/log.txt?id=4742532743299072
>> Kernel config: https://syzkaller.appspot.com/x/.config?id=-8440362230543204781
>> compiler: gcc (GCC) 7.1.1 20170620
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+dc5ca0e4c9bfafaf2bae@syzkaller.appspotmail.com
>> It will help syzbot understand when the bug is fixed. See footer for details.
>> If you forward the report, please keep this part and the footer.
>>
>>
>> ======================================================
>> WARNING: possible circular locking dependency detected
>> 4.16.0-rc7+ #3 Not tainted
>> ------------------------------------------------------
>> syz-executor7/24531 is trying to acquire lock:
>> (bpf_event_mutex){+.+.}, at: [<000000008a849b07>] perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854
>>
>> but task is already holding lock:
>> (&mm->mmap_sem){++++}, at: [<0000000038768f87>] vm_mmap_pgoff+0x198/0x280 mm/util.c:353
>>
>> which lock already depends on the new lock.
>>
>>
>> the existing dependency chain (in reverse order) is:
>>
>> -> #1 (&mm->mmap_sem){++++}:
>> __might_fault+0x13a/0x1d0 mm/memory.c:4571
>> _copy_to_user+0x2c/0xc0 lib/usercopy.c:25
>> copy_to_user include/linux/uaccess.h:155 [inline]
>> bpf_prog_array_copy_info+0xf2/0x1c0 kernel/bpf/core.c:1694
>> perf_event_query_prog_array+0x1c7/0x2c0 kernel/trace/bpf_trace.c:891
>
> Looks like we should move the two copy_to_user() outside of
> bpf_event_mutex section to avoid the deadlock.
This is introduced by one of my previous patches. The above suggested fix
makes sense. I will craft a patch and send to the mailing list for bpf branch
soon.
>
>> _perf_ioctl kernel/events/core.c:4750 [inline]
>> perf_ioctl+0x3e1/0x1480 kernel/events/core.c:4770
>> vfs_ioctl fs/ioctl.c:46 [inline]
>> do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
>> SYSC_ioctl fs/ioctl.c:701 [inline]
>> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
>> do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
>> entry_SYSCALL_64_after_hwframe+0x42/0xb7
>>
>> -> #0 (bpf_event_mutex){+.+.}:
>> lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
>> __mutex_lock_common kernel/locking/mutex.c:756 [inline]
>> __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
>> mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
>> perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854
>> perf_event_free_bpf_prog kernel/events/core.c:8147 [inline]
>> _free_event+0xbdb/0x10f0 kernel/events/core.c:4116
>> put_event+0x24/0x30 kernel/events/core.c:4204
>> perf_mmap_close+0x60d/0x1010 kernel/events/core.c:5172
>> remove_vma+0xb4/0x1b0 mm/mmap.c:172
>> remove_vma_list mm/mmap.c:2490 [inline]
>> do_munmap+0x82a/0xdf0 mm/mmap.c:2731
>> mmap_region+0x59e/0x15a0 mm/mmap.c:1646
>> do_mmap+0x6c0/0xe00 mm/mmap.c:1483
>> do_mmap_pgoff include/linux/mm.h:2223 [inline]
>> vm_mmap_pgoff+0x1de/0x280 mm/util.c:355
>> SYSC_mmap_pgoff mm/mmap.c:1533 [inline]
>> SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491
>> SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
>> SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91
>> do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
>> entry_SYSCALL_64_after_hwframe+0x42/0xb7
>>
>> other info that might help us debug this:
>>
>> Possible unsafe locking scenario:
>>
>> CPU0 CPU1
>> ---- ----
>> lock(&mm->mmap_sem);
>> lock(bpf_event_mutex);
>> lock(&mm->mmap_sem);
>> lock(bpf_event_mutex);
>>
>> *** DEADLOCK ***
>>
>> 1 lock held by syz-executor7/24531:
>> #0: (&mm->mmap_sem){++++}, at: [<0000000038768f87>] vm_mmap_pgoff+0x198/0x280 mm/util.c:353
>>
>> stack backtrace:
>> CPU: 0 PID: 24531 Comm: syz-executor7 Not tainted 4.16.0-rc7+ #3
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>> Call Trace:
>> __dump_stack lib/dump_stack.c:17 [inline]
>> dump_stack+0x194/0x24d lib/dump_stack.c:53
>> print_circular_bug.isra.38+0x2cd/0x2dc kernel/locking/lockdep.c:1223
>> check_prev_add kernel/locking/lockdep.c:1863 [inline]
>> check_prevs_add kernel/locking/lockdep.c:1976 [inline]
>> validate_chain kernel/locking/lockdep.c:2417 [inline]
>> __lock_acquire+0x30a8/0x3e00 kernel/locking/lockdep.c:3431
>> lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
>> __mutex_lock_common kernel/locking/mutex.c:756 [inline]
>> __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
>> mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
>> perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854
>> perf_event_free_bpf_prog kernel/events/core.c:8147 [inline]
>> _free_event+0xbdb/0x10f0 kernel/events/core.c:4116
>> put_event+0x24/0x30 kernel/events/core.c:4204
>> perf_mmap_close+0x60d/0x1010 kernel/events/core.c:5172
>> remove_vma+0xb4/0x1b0 mm/mmap.c:172
>> remove_vma_list mm/mmap.c:2490 [inline]
>> do_munmap+0x82a/0xdf0 mm/mmap.c:2731
>> mmap_region+0x59e/0x15a0 mm/mmap.c:1646
>> do_mmap+0x6c0/0xe00 mm/mmap.c:1483
>> do_mmap_pgoff include/linux/mm.h:2223 [inline]
>> vm_mmap_pgoff+0x1de/0x280 mm/util.c:355
>> SYSC_mmap_pgoff mm/mmap.c:1533 [inline]
>> SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491
>> SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
>> SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91
>> do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
>> entry_SYSCALL_64_after_hwframe+0x42/0xb7
>> RIP: 0033:0x454889
>> RSP: 002b:00007f5f44fdac68 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
>> RAX: ffffffffffffffda RBX: 00007f5f44fdb6d4 RCX: 0000000000454889
>> RDX: 0000000000000000 RSI: 0000000000002000 RDI: 0000000020f1f000
>> RBP: 000000000072c010 R08: 0000000000000014 R09: 0000000000000000
>> R10: 0000000000000011 R11: 0000000000000246 R12: 00000000ffffffff
>> R13: 00000000000003f4 R14: 00000000006f7f80 R15: 0000000000000002
>> bond0 (unregistering): Released all slaves
>> IPVS: ftp: loaded support on port[0] = 21
>> IPv6: ADDRCONF(NETDEV_UP): bridge0: link is not ready
>> IPv6: ADDRCONF(NETDEV_UP): bond0: link is not ready
>> 8021q: adding VLAN 0 to HW filter on device bond0
>> IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready
>> IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
>> kernel msg: ebtables bug: please report to author: Wrong len argument
>> kernel msg: ebtables bug: please report to author: Wrong len argument
>> kernel msg: ebtables bug: please report to author: Wrong len argument
>> kernel msg: ebtables bug: please report to author: Wrong len argument
>> kernel msg: ebtables bug: please report to author: Wrong len argument
>> kernel msg: ebtables bug: please report to author: Wrong len argument
>> kernel msg: ebtables bug: please report to author: Wrong len argument
>>
>>
>> ---
>> This bug is generated by a dumb bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for details.
>> Direct all questions to syzkaller@googlegroups.com.
>>
>> syzbot will keep track of this bug report.
>> If you forgot to add the Reported-by tag, once the fix for this bug is merged
>> into any tree, please reply to this email with:
>> #syz fix: exact-commit-title
>> To mark this as a duplicate of another syzbot report, please reply with:
>> #syz dup: exact-subject-of-another-report
>> If it's a one-off invalid bug report, please reply with:
>> #syz invalid
>> Note: if the crash happens again, it will cause creation of a new bug report.
>> Note: all commands must start from beginning of the line in the email body.
>
^ permalink raw reply
* Re: [PATCH net] sctp: sctp_sockaddr_af must check minimal addr length for AF_INET6
From: David Miller @ 2018-04-08 16:30 UTC (permalink / raw)
To: edumazet; +Cc: netdev, eric.dumazet, vyasevich, nhorman
In-Reply-To: <20180408145208.228542-1-edumazet@google.com>
From: Eric Dumazet <edumazet@google.com>
Date: Sun, 8 Apr 2018 07:52:08 -0700
> Check must happen before call to ipv6_addr_v4mapped()
>
> syzbot report was :
...
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Vlad Yasevich <vyasevich@gmail.com>
> Cc: Neil Horman <nhorman@tuxdriver.com>
> Reported-by: syzbot <syzkaller@googlegroups.com>
Applied and queued up for -stable, thanks Eric.
^ permalink raw reply
* Re: [RFC PATCH 2/3] netdev: kernel-only IFF_HIDDEN netdevice
From: David Miller @ 2018-04-08 16:32 UTC (permalink / raw)
To: loseweigh
Cc: dsahern, jiri, si-wei.liu, mst, stephen, alexander.h.duyck,
jesse.brandeburg, kubakici, jasowang, sridhar.samudrala, netdev,
virtualization, virtio-dev
In-Reply-To: <CADGSJ206RKi704uoLe3xVs6PyWpURPLb75OPCM_YO9DfnnEzpw@mail.gmail.com>
From: Siwei Liu <loseweigh@gmail.com>
Date: Fri, 6 Apr 2018 19:32:05 -0700
> And I assume everyone here understands the use case for live
> migration (in the context of providing cloud service) is very
> different, and we have to hide the netdevs. If not, I'm more than
> happy to clarify.
I think you still need to clarify.
netdevs are netdevs. If they have special attributes, mark them as
such and the tools base their actions upon that.
"Hiding", or changing classes, doesn't make any sense to me still.
^ permalink raw reply
* Re: [Patch net] tipc: use the right skb in tipc_sk_fill_sock_diag()
From: David Miller @ 2018-04-08 16:34 UTC (permalink / raw)
To: xiyou.wangcong
Cc: netdev, mohan.krishna.ghanta.krishnamurthy, jon.maloy, ying.xue
In-Reply-To: <20180407015452.26636-1-xiyou.wangcong@gmail.com>
From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Fri, 6 Apr 2018 18:54:52 -0700
> Commit 4b2e6877b879 ("tipc: Fix namespace violation in tipc_sk_fill_sock_diag")
> tried to fix the crash but failed, the crash is still 100% reproducible
> with it.
>
> In tipc_sk_fill_sock_diag(), skb is the diag dump we are filling, it is not
> correct to retrieve its NETLINK_CB(), instead, like other protocol diag,
> we should use NETLINK_CB(cb->skb).sk here.
>
> Reported-by: <syzbot+326e587eff1074657718@syzkaller.appspotmail.com>
> Fixes: 4b2e6877b879 ("tipc: Fix namespace violation in tipc_sk_fill_sock_diag")
> Fixes: c30b70deb5f4 (tipc: implement socket diagnostics for AF_TIPC)
> Cc: GhantaKrishnamurthy MohanKrishna <mohan.krishna.ghanta.krishnamurthy@ericsson.com>
> Cc: Jon Maloy <jon.maloy@ericsson.com>
> Cc: Ying Xue <ying.xue@windriver.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Applied, thank you.
^ permalink raw reply
* Re: [PATCH net 0/8] net: fix uninit-values in networking stack
From: Eric Dumazet @ 2018-04-08 16:38 UTC (permalink / raw)
To: David Miller, edumazet; +Cc: netdev
In-Reply-To: <20180407.224025.1923207101579714958.davem@davemloft.net>
On 04/07/2018 07:40 PM, David Miller wrote:
> From: Eric Dumazet <edumazet@google.com>
> Date: Sat, 7 Apr 2018 13:42:35 -0700
>
>> It seems syzbot got new features enabled, and fired some interesting
>> reports. Oh well.
>
> Series applied, however in patch #7 the condition syzbot detects
> cannot happen.
>
> In all code paths that lead to __mkroute_output() with res->type
> uninitialized, __mkroute_output() will reassign the local variable
> 'type' before reading it.
Well, we have :
u16 type = res->type;
...
if (ipv4_is_lbcast(fl4->daddr))
type = RTN_BROADCAST;
else if (ipv4_is_multicast(fl4->daddr))
type = RTN_MULTICAST;
else if (ipv4_is_zeronet(fl4->daddr))
return ERR_PTR(-EINVAL);
...
if (type == RTN_BROADCAST) { /* This is where KMSAN complained */
So it looks like type could have been random at this point.
>
> Furthermore, by doing a full structure initialization lots of
> unrelated things will be initialized now as well.
fib_result is 40 bytes on 64bit arches.
>
> We explicitly are only setting up the "inputs" of the fib_result
> object before we call fib_lookup(). The prefixlen and other members
> have no business being initialized there.
>
Yep
We might put all inputs at the beginning of the structure,
and output at the end. then replace sizeof() by offsetof(),
but this looks a bit convoluted and maybe risky.
^ permalink raw reply
* Re: [PATCH net 0/5] ibmvnic: Fix driver reset and DMA bugs
From: David Miller @ 2018-04-08 16:40 UTC (permalink / raw)
To: tlfalcon; +Cc: netdev, jallen, nfont
In-Reply-To: <1523057826-5262-1-git-send-email-tlfalcon@linux.vnet.ibm.com>
From: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Date: Fri, 6 Apr 2018 18:37:01 -0500
> This patch series introduces some fixes to the driver reset
> routines and a patch that fixes mistakes caught by the kernel
> DMA debugger.
>
> The reset fixes include a fix to reset TX queue counters properly
> after a reset as well as updates to driver reset error-handling code.
> It also provides updates to the reset handling routine for redundant
> backing VF failover and partition migration cases.
Series applied, thanks Thomas.
^ permalink raw reply
* Re: [PATCH v4] net: thunderx: rework mac addresses list to u64 array
From: David Miller @ 2018-04-08 16:42 UTC (permalink / raw)
To: Vadim.Lomovtsev
Cc: sgoutham, sunil.kovvuri, rric, linux-arm-kernel, netdev,
linux-kernel, dnelson, robin.murphy, hch, gustavo,
Vadim.Lomovtsev
In-Reply-To: <20180406195354.16037-1-Vadim.Lomovtsev@caviumnetworks.com>
From: Vadim Lomovtsev <Vadim.Lomovtsev@caviumnetworks.com>
Date: Fri, 6 Apr 2018 12:53:54 -0700
> @@ -1929,7 +1929,7 @@ static void nicvf_set_rx_mode_task(struct work_struct *work_arg)
> work.work);
> struct nicvf *nic = container_of(vf_work, struct nicvf, rx_mode_work);
> union nic_mbx mbx = {};
> - struct xcast_addr *xaddr, *next;
> + int idx = 0;
No need to initialize idx.
> + for (idx = 0; idx < vf_work->mc->count; idx++) {
As it is always explicitly initialized at, and only used inside of,
this loop.
^ permalink raw reply
* Re: [PATCH 1/2] net/fsl_pq_mdio: Allow explicit speficition of TBIPA address
From: David Miller @ 2018-04-08 16:45 UTC (permalink / raw)
To: esben.haabendal
Cc: netdev, eha, claudiu.manoil, robh+dt, mark.rutland, garsilva,
devicetree, linux-kernel
In-Reply-To: <20180406123836.12019-1-esben.haabendal@gmail.com>
From: Esben Haabendal <esben.haabendal@gmail.com>
Date: Fri, 6 Apr 2018 14:38:34 +0200
> From: Esben Haabendal <eha@deif.com>
>
> This introduces a simpler and generic method for for finding (and mapping)
> the TBIPA register.
>
> Instead of relying of complicated logic for finding the TBIPA register
> address based on the MDIO or MII register block base
> address, which even in some cases relies on undocumented shadow registers,
> a second "reg" entry for the mdio bus devicetree node specifies the TBIPA
> register.
>
> Backwards compatibility is kept, as the existing logic is applied when
> only a single "reg" mapping is specified.
>
> Signed-off-by: Esben Haabendal <eha@deif.com>
Applied.
^ permalink raw reply
* Re: [PATCH] ARM: dts: ls1021a: Specify TBIPA register address
From: David Miller @ 2018-04-08 16:45 UTC (permalink / raw)
To: esben.haabendal
Cc: netdev, robh+dt, mark.rutland, devicetree, linux-kernel,
claudiu.manoil, garsilva, eha
In-Reply-To: <20180406124635.12319-1-esben.haabendal@gmail.com>
From: Esben Haabendal <esben.haabendal@gmail.com>
Date: Fri, 6 Apr 2018 14:46:35 +0200
> From: Esben Haabendal <eha@deif.com>
>
> The current (mildly evil) fsl_pq_mdio code uses an undocumented shadow of
> the TBIPA register on LS1021A, which happens to be read-only.
> Changing TBI PHY address therefore does not work on LS1021A.
>
> The real (and documented) address of the TBIPA registere lies in the eTSEC
> block and not in MDIO/MII, which is read/write, so using that fixes
> the problem.
>
> Signed-off-by: Esben Haabendal <eha@deif.com>
Applied.
^ permalink raw reply
* Re: [patch net] devlink: convert occ_get op to separate registration
From: David Miller @ 2018-04-08 16:46 UTC (permalink / raw)
To: jiri; +Cc: netdev, idosch, jakub.kicinski, dsahern, mlxsw
In-Reply-To: <20180405201321.16626-1-jiri@resnulli.us>
From: Jiri Pirko <jiri@resnulli.us>
Date: Thu, 5 Apr 2018 22:13:21 +0200
> From: Jiri Pirko <jiri@mellanox.com>
>
> This resolves race during initialization where the resources with
> ops are registered before driver and the structures used by occ_get
> op is initialized. So keep occ_get callbacks registered only when
> all structs are initialized.
...
> Fixes: d9f9b9a4d05f ("devlink: Add support for resource abstraction")
> Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Applied and queued up for -stable, thanks.
^ permalink raw reply
* Re: [PATCH net 0/8] net: fix uninit-values in networking stack
From: David Miller @ 2018-04-08 16:49 UTC (permalink / raw)
To: eric.dumazet; +Cc: edumazet, netdev
In-Reply-To: <3748e283-5172-199c-660d-6814afe51823@gmail.com>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Sun, 8 Apr 2018 09:38:13 -0700
> On 04/07/2018 07:40 PM, David Miller wrote:
>> From: Eric Dumazet <edumazet@google.com>
>> Date: Sat, 7 Apr 2018 13:42:35 -0700
>>
>>> It seems syzbot got new features enabled, and fired some interesting
>>> reports. Oh well.
>>
>> Series applied, however in patch #7 the condition syzbot detects
>> cannot happen.
>>
>> In all code paths that lead to __mkroute_output() with res->type
>> uninitialized, __mkroute_output() will reassign the local variable
>> 'type' before reading it.
>
> Well, we have :
>
> u16 type = res->type;
> ...
>
> if (ipv4_is_lbcast(fl4->daddr))
> type = RTN_BROADCAST;
> else if (ipv4_is_multicast(fl4->daddr))
> type = RTN_MULTICAST;
> else if (ipv4_is_zeronet(fl4->daddr))
> return ERR_PTR(-EINVAL);
>
> ...
>
> if (type == RTN_BROADCAST) { /* This is where KMSAN complained */
>
> So it looks like type could have been random at this point.
Ok, then. It seems that the requirement is:
fl4->flowi4_oif is non-zero
fl4->daddr is neither local multicast nor lbcast
fl4->flowi4_proto is IPPROTO_IGMP
Then we can trigger such a sequence of events.
^ permalink raw reply
* Re: [PATCH] make net_gso_ok return false when gso_type is zero(invalid)
From: David Miller @ 2018-04-08 16:51 UTC (permalink / raw)
To: march511; +Cc: netdev, linux-kernel
In-Reply-To: <20180406014340.1562-1-march511@gmail.com>
From: Wenhua Shi <march511@gmail.com>
Date: Fri, 6 Apr 2018 03:43:39 +0200
> Signed-off-by: Wenhua Shi <march511@gmail.com>
This precondition should be made impossible instead of having to do
an extra check everywhere that this helper is invoked, many of which
are in fast paths.
^ permalink raw reply
* Re: [PATCH] vhost-net: set packet weight of tx polling to 2 * vq size
From: David Miller @ 2018-04-08 16:52 UTC (permalink / raw)
To: haibinzhang
Cc: mst, jasowang, kvm, virtualization, netdev, linux-kernel,
lidongchen, yunfangtai
In-Reply-To: <88D661ADF6AFBF42B2AB88D8E7682B0901FC47D3@EXMBX-SZMAIL011.tencent.com>
From: haibinzhang(张海斌) <haibinzhang@tencent.com>
Date: Fri, 6 Apr 2018 08:22:37 +0000
> handle_tx will delay rx for tens or even hundreds of milliseconds when tx busy
> polling udp packets with small length(e.g. 1byte udp payload), because setting
> VHOST_NET_WEIGHT takes into account only sent-bytes but no single packet length.
>
> Ping-Latencies shown below were tested between two Virtual Machines using
> netperf (UDP_STREAM, len=1), and then another machine pinged the client:
...
> Signed-off-by: Haibin Zhang <haibinzhang@tencent.com>
> Signed-off-by: Yunfang Tai <yunfangtai@tencent.com>
> Signed-off-by: Lidong Chen <lidongchen@tencent.com>
Michael and Jason, please review.
^ permalink raw reply
* Re: [PATCH net 0/8] net: fix uninit-values in networking stack
From: Eric Dumazet @ 2018-04-08 16:55 UTC (permalink / raw)
To: David Miller; +Cc: edumazet, netdev
In-Reply-To: <20180408.124959.590910633534141941.davem@davemloft.net>
On 04/08/2018 09:49 AM, David Miller wrote:
> From: Eric Dumazet <eric.dumazet@gmail.com>
> Date: Sun, 8 Apr 2018 09:38:13 -0700
>
>> On 04/07/2018 07:40 PM, David Miller wrote:
>>> From: Eric Dumazet <edumazet@google.com>
>>> Date: Sat, 7 Apr 2018 13:42:35 -0700
>>>
>>>> It seems syzbot got new features enabled, and fired some interesting
>>>> reports. Oh well.
>>>
>>> Series applied, however in patch #7 the condition syzbot detects
>>> cannot happen.
>>>
>>> In all code paths that lead to __mkroute_output() with res->type
>>> uninitialized, __mkroute_output() will reassign the local variable
>>> 'type' before reading it.
>>
>> Well, we have :
>>
>> u16 type = res->type;
>> ...
>>
>> if (ipv4_is_lbcast(fl4->daddr))
>> type = RTN_BROADCAST;
>> else if (ipv4_is_multicast(fl4->daddr))
>> type = RTN_MULTICAST;
>> else if (ipv4_is_zeronet(fl4->daddr))
>> return ERR_PTR(-EINVAL);
>>
>> ...
>>
>> if (type == RTN_BROADCAST) { /* This is where KMSAN complained */
>>
>> So it looks like type could have been random at this point.
>
> Ok, then. It seems that the requirement is:
>
> fl4->flowi4_oif is non-zero
> fl4->daddr is neither local multicast nor lbcast
> fl4->flowi4_proto is IPPROTO_IGMP
>
> Then we can trigger such a sequence of events.
>
OK, maybe some more work then ;)
I also have a report of a WARN() in ip_rt_bug(), added in commit c378a9c019cf5e017d1ed24954b54fae7bebd2bc
by Dave Jones.
Not sure what to do, maybe revert, since ip_rt_bug() is not catastrophic.
WARNING: CPU: 0 PID: 11678 at net/ipv4/route.c:1213 ip_rt_bug+0x15/0x20 net/ipv4/route.c:1212
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 11678 Comm: kworker/u4:7 Not tainted 4.16.0-rc6+ #289
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x24d lib/dump_stack.c:53
panic+0x1e4/0x41c kernel/panic.c:183
__warn+0x1dc/0x200 kernel/panic.c:547
report_bug+0x1f4/0x2b0 lib/bug.c:186
fixup_bug.part.10+0x37/0x80 arch/x86/kernel/traps.c:178
fixup_bug arch/x86/kernel/traps.c:247 [inline]
do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:986
RIP: 0010:ip_rt_bug+0x15/0x20 net/ipv4/route.c:1212
RSP: 0018:ffff8801db007290 EFLAGS: 00010282
RAX: dffffc0000000000 RBX: ffff8801d8dda3c0 RCX: ffffffff856c31ca
RDX: 0000000000000100 RSI: ffffffff8858c300 RDI: 0000000000000282
RBP: ffff8801db007298 R08: 1ffff1003b600de1 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d8dda3c0
R13: ffff88019bdb2200 R14: ffff88019bdeed80 R15: ffff8801d8dda418
dst_output include/net/dst.h:444 [inline]
ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124
ip_send_skb+0x3c/0xc0 net/ipv4/ip_output.c:1414
ip_push_pending_frames+0x64/0x80 net/ipv4/ip_output.c:1434
icmp_push_reply+0x395/0x4f0 net/ipv4/icmp.c:394
icmp_send+0x1136/0x19b0 net/ipv4/icmp.c:741
ipv4_link_failure+0x2a/0x1b0 net/ipv4/route.c:1200
dst_link_failure include/net/dst.h:427 [inline]
arp_error_report+0xae/0x180 net/ipv4/arp.c:297
neigh_invalidate+0x225/0x530 net/core/neighbour.c:883
neigh_timer_handler+0x897/0xd60 net/core/neighbour.c:969
call_timer_fn+0x228/0x820 kernel/time/timer.c:1326
expire_timers kernel/time/timer.c:1363 [inline]
__run_timers+0x7ee/0xb70 kernel/time/timer.c:1666
run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692
__do_softirq+0x2d7/0xb85 kernel/softirq.c:285
invoke_softirq kernel/softirq.c:365 [inline]
irq_exit+0x1cc/0x200 kernel/softirq.c:405
exiting_irq arch/x86/include/asm/apic.h:541 [inline]
smp_apic_timer_interrupt+0x16b/0x700 arch/x86/kernel/apic/apic.c:1052
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:857
</IRQ>
^ permalink raw reply
* pull request: bluetooth 2018-04-08
From: Johan Hedberg @ 2018-04-08 17:47 UTC (permalink / raw)
To: davem; +Cc: linux-bluetooth, netdev
[-- Attachment #1: Type: text/plain, Size: 1135 bytes --]
Hi Dave,
Here's one important Bluetooth fix for the 4.17-rc series that's needed
to pass several Bluetooth qualification test cases.
Let me know if there are any issues pulling. Thanks.
Johan
---
The following changes since commit b5dbc28762fd3fd40ba76303be0c7f707826f982:
Merge tag 'kbuild-fixes-v4.16-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild (2018-03-30 18:53:57 -1000)
are available in the Git repository at:
git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git for-upstream
for you to fetch changes up to 082f2300cfa1a3d9d5221c38c5eba85d4ab98bd8:
Bluetooth: Fix connection if directed advertising and privacy is used (2018-04-03 16:12:56 +0200)
----------------------------------------------------------------
Szymon Janc (1):
Bluetooth: Fix connection if directed advertising and privacy is used
include/net/bluetooth/hci_core.h | 2 +-
net/bluetooth/hci_conn.c | 29 +++++++++++++++++++++--------
net/bluetooth/hci_event.c | 15 +++++++++++----
net/bluetooth/l2cap_core.c | 2 +-
4 files changed, 34 insertions(+), 14 deletions(-)
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 801 bytes --]
^ permalink raw reply
* [PATCH] net: bridge: add missing NULL checks
From: Laszlo Toth @ 2018-04-08 17:49 UTC (permalink / raw)
To: Stephen Hemminger, David S. Miller; +Cc: bridge, netdev
br_port_get_rtnl() can return NULL
Signed-off-by: Laszlo Toth <laszlth@gmail.com>
---
net/bridge/br_netlink.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 015f465c..cbec11f 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -939,14 +939,17 @@ static int br_port_slave_changelink(struct net_device *brdev,
struct nlattr *data[],
struct netlink_ext_ack *extack)
{
+ struct net_bridge_port *port = br_port_get_rtnl(dev);
struct net_bridge *br = netdev_priv(brdev);
int ret;
if (!data)
return 0;
+ if (!port)
+ return -EINVAL;
spin_lock_bh(&br->lock);
- ret = br_setport(br_port_get_rtnl(dev), data);
+ ret = br_setport(port, data);
spin_unlock_bh(&br->lock);
return ret;
@@ -956,7 +959,12 @@ static int br_port_fill_slave_info(struct sk_buff *skb,
const struct net_device *brdev,
const struct net_device *dev)
{
- return br_port_fill_attrs(skb, br_port_get_rtnl(dev));
+ struct net_bridge_port *port = br_port_get_rtnl(dev);
+
+ if (!port)
+ return -EINVAL;
+
+ return br_port_fill_attrs(skb, port);
}
static size_t br_port_get_slave_size(const struct net_device *brdev,
--
2.7.4
^ permalink raw reply related
* Re: [PATCH iproute2-next 1/1] tc: jsonify skbedit action
From: David Ahern @ 2018-04-08 17:50 UTC (permalink / raw)
To: Roman Mashak, dsahern; +Cc: stephen, netdev, kernel, jhs, xiyou.wangcong, jiri
In-Reply-To: <1522783461-14269-1-git-send-email-mrv@mojatatu.com>
On 4/3/18 1:24 PM, Roman Mashak wrote:
> if (tb[TCA_SKBEDIT_PTYPE] != NULL) {
> - ptype = RTA_DATA(tb[TCA_SKBEDIT_PTYPE]);
> - if (*ptype == PACKET_HOST)
> - fprintf(f, " ptype host");
> - else if (*ptype == PACKET_BROADCAST)
> - fprintf(f, " ptype broadcast");
> - else if (*ptype == PACKET_MULTICAST)
> - fprintf(f, " ptype multicast");
> - else if (*ptype == PACKET_OTHERHOST)
> - fprintf(f, " ptype otherhost");
> + ptype = rta_getattr_u16(tb[TCA_SKBEDIT_PTYPE]);
> + if (ptype == PACKET_HOST)
> + print_string(PRINT_ANY, "ptype", " %s", "ptype host");
> + else if (ptype == PACKET_BROADCAST)
> + print_string(PRINT_ANY, "ptype", " %s",
> + "ptype broadcast");
> + else if (ptype == PACKET_MULTICAST)
> + print_string(PRINT_ANY, "ptype", " %s",
> + "ptype multicast");
> + else if (ptype == PACKET_OTHERHOST)
> + print_string(PRINT_ANY, "ptype", " %s",
> + "ptype otherhost");
Shouldn't that be:
print_string(PRINT_ANY, "ptype", "ptype %s", "otherhost");
And ditto for the other strings.
> else
> - fprintf(f, " ptype %d", *ptype);
> + print_uint(PRINT_ANY, "ptype", " %u", ptype);
And then this one needs 'ptype' before %u
^ permalink raw reply
* Re: [PATCH iproute2-next 1/1] tc: jsonify connmark action
From: David Ahern @ 2018-04-08 17:54 UTC (permalink / raw)
To: Roman Mashak; +Cc: stephen, netdev, kernel, jhs, xiyou.wangcong, jiri
In-Reply-To: <1522760995-12441-1-git-send-email-mrv@mojatatu.com>
On 4/3/18 7:09 AM, Roman Mashak wrote:
> Signed-off-by: Roman Mashak <mrv@mojatatu.com>
> ---
> tc/m_connmark.c | 16 ++++++++++------
> 1 file changed, 10 insertions(+), 6 deletions(-)
applied to iproute2-next
^ permalink raw reply
* Re: [PATCH iproute2-next 1/1] tc: jsonify tunnel_key action
From: David Ahern @ 2018-04-08 17:54 UTC (permalink / raw)
To: Roman Mashak; +Cc: stephen, netdev, kernel, jhs, xiyou.wangcong, jiri
In-Reply-To: <1522862478-24580-1-git-send-email-mrv@mojatatu.com>
On 4/4/18 11:21 AM, Roman Mashak wrote:
> Signed-off-by: Roman Mashak <mrv@mojatatu.com>
> ---
> tc/m_tunnel_key.c | 36 +++++++++++++++++++++++++-----------
> 1 file changed, 25 insertions(+), 11 deletions(-)
>
applied to iproute2-next
^ permalink raw reply
* Re: [PATCH] make net_gso_ok return false when gso_type is zero(invalid)
From: Wenhua Shi @ 2018-04-08 18:41 UTC (permalink / raw)
To: David Miller; +Cc: netdev, linux-kernel
In-Reply-To: <20180408.125114.2111042327285982582.davem@davemloft.net>
2018-04-08 18:51 GMT+02:00 David Miller <davem@davemloft.net>:
>
> From: Wenhua Shi <march511@gmail.com>
> Date: Fri, 6 Apr 2018 03:43:39 +0200
>
> > Signed-off-by: Wenhua Shi <march511@gmail.com>
>
> This precondition should be made impossible instead of having to do
> an extra check everywhere that this helper is invoked, many of which
> are in fast paths.
I believe the precondition you said is quite true. In my situation, I
have to disable GSO for some packet and I notice that it leads to a
worse performance (slower than 1Mbps, was almost 800Mbps).
Here's the hook I use on debian 9.4, kernel version 4.9:
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <linux/skbuff.h>
#include <linux/tcp.h>
#include <linux/ip.h>
unsigned int hook_outgoing (
void * priv,
struct sk_buff * skb,
const struct nf_hook_state * state)
{
/* for some reason I have to disable GSO */
skb_gso_reset(skb);
/* After I force sk_can_gso to return false here, the
performance comes back normal. */
// skb->sk->sk_gso_type = ~0;
return NF_ACCEPT;
}
static struct nf_hook_ops hook =
{
.hook = hook_outgoing,
.pf = PF_INET,
.hooknum = NF_INET_POST_ROUTING,
.priority = NF_IP_PRI_LAST,
};
static int __init init_testing(void)
{
nf_register_hook(&hook);
return 0;
}
static void __exit exit_testing(void)
{
nf_unregister_hook(&hook);
}
module_init(init_testing);
module_exit(exit_testing);
Here are the performance measurements.
Without the previous hook:
root@debian-s-1vcpu-1gb-sfo1-01:~/test# iperf -c myanothernormaldebian -d
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to myanothernormaldebian, TCP port 5001
TCP window size: 255 KByte (default)
------------------------------------------------------------
[ 3] local 192.241.204.XXX port 60528 connected with
104.131.148.XXX port 5001
[ 5] local 192.241.204.XXX port 5001 connected with
104.131.148.XXX port 58576
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 922 MBytes 773 Mbits/sec
[ 5] 0.0-10.1 sec 1.00 GBytes 849 Mbits/sec
And with the previous hook:
root@debian-s-1vcpu-1gb-sfo1-01:~/test# iperf -c myanothernormaldebian -d
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to myanothernormaldebian, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[ 3] local 192.241.204.XXX port 60530 connected with
104.131.148.XXX port 5001
[ 5] local 192.241.204.XXX port 5001 connected with
104.131.148.XXX port 58578
[ ID] Interval Transfer Bandwidth
[ 5] 0.0-10.2 sec 1.02 GBytes 864 Mbits/sec
[ 3] 0.0-13.5 sec 170 KBytes 103 Kbits/sec
Or it's just because of that I'm disabling the GSO in a wrong way?
^ permalink raw reply
* Re: suspicious RCU usage at ./include/net/inet_sock.h:LINE
From: Eric Biggers @ 2018-04-08 19:29 UTC (permalink / raw)
To: syzbot
Cc: davem, dccp, dvyukov, gerrit, kuznet, linux-kernel, netdev,
syzkaller-bugs, yoshfuji
In-Reply-To: <001a113f8d5653a67c0561346ed3@google.com>
On Mon, Dec 25, 2017 at 05:45:00PM -0800, syzbot wrote:
> syzkaller has found reproducer for the following crash on
> fba961ab29e5ffb055592442808bb0f7962e05da
> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> C reproducer is attached
> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> for information about syzkaller reproducers
>
>
> Can not set IPV6_FL_F_REFLECT if flowlabel_consistency sysctl is enable
>
> =============================
> WARNING: suspicious RCU usage
> 4.15.0-rc4+ #164 Not tainted
> -----------------------------
> ./include/net/inet_sock.h:136 suspicious rcu_dereference_check() usage!
>
> other info that might help us debug this:
>
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by syzkaller667189/5780:
> #0: (sk_lock-AF_INET6){+.+.}, at: [<000000008d7d4e62>] lock_sock
> include/net/sock.h:1462 [inline]
> #0: (sk_lock-AF_INET6){+.+.}, at: [<000000008d7d4e62>]
> do_ipv6_setsockopt.isra.9+0x23d/0x38f0 net/ipv6/ipv6_sockglue.c:167
>
> stack backtrace:
> CPU: 0 PID: 5780 Comm: syzkaller667189 Not tainted 4.15.0-rc4+ #164
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:17 [inline]
> dump_stack+0x194/0x257 lib/dump_stack.c:53
> lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4585
> ireq_opt_deref include/net/inet_sock.h:135 [inline]
> inet_csk_route_req+0x824/0xca0 net/ipv4/inet_connection_sock.c:544
> dccp_v4_send_response+0xa7/0x640 net/dccp/ipv4.c:485
> dccp_v4_conn_request+0x9ee/0x11b0 net/dccp/ipv4.c:633
> dccp_v6_conn_request+0xd30/0x1350 net/dccp/ipv6.c:317
> dccp_rcv_state_process+0x574/0x1620 net/dccp/input.c:612
> dccp_v4_do_rcv+0xeb/0x160 net/dccp/ipv4.c:682
> dccp_v6_do_rcv+0x81a/0x9b0 net/dccp/ipv6.c:578
> sk_backlog_rcv include/net/sock.h:907 [inline]
> __release_sock+0x124/0x360 net/core/sock.c:2274
> release_sock+0xa4/0x2a0 net/core/sock.c:2789
> do_ipv6_setsockopt.isra.9+0x50f/0x38f0 net/ipv6/ipv6_sockglue.c:898
> ipv6_setsockopt+0xd7/0x150 net/ipv6/ipv6_sockglue.c:922
> dccp_setsockopt+0x85/0xd0 net/dccp/proto.c:573
> sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2978
> SYSC_setsockopt net/socket.c:1821 [inline]
> SyS_setsockopt+0x189/0x360 net/socket.c:1800
> entry_SYSCALL_64_fastpath+0x1f/0x96
> RIP: 0033:0x445ec9
> RSP: 002b:00007fa001b58db8 EFLAGS: 00000297 ORIG_RAX: 0000000000000036
> RAX: ffffffffffffffda RBX: 00000000006dbc24 RCX: 0000000000445ec9
> RDX: 0000000000000020 RSI: 0000000000000029 RDI: 0000000000000004
> RBP: 00000000006dbc20 R08: 0000000000000020 R09: 0000000000000000
> R10: 000000002030a000 R11: 0000000000000297 R12: 0000000000000000
> R13: 00007fff809eec1f R14: 00007fa001b599c0 R15: 0000000000000001
>
> =============================
> WARNING: suspicious RCU usage
> 4.15.0-rc4+ #164 Not tainted
> -----------------------------
> ./include/net/inet_sock.h:136 suspicious rcu_dereference_check() usage!
>
> other info that might help us debug this:
>
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by syzkaller667189/5780:
> #0: (sk_lock-AF_INET6){+.+.}, at: [<000000008d7d4e62>] lock_sock
> include/net/sock.h:1462 [inline]
> #0: (sk_lock-AF_INET6){+.+.}, at: [<000000008d7d4e62>]
> do_ipv6_setsockopt.isra.9+0x23d/0x38f0 net/ipv6/ipv6_sockglue.c:167
>
> stack backtrace:
> CPU: 0 PID: 5780 Comm: syzkaller667189 Not tainted 4.15.0-rc4+ #164
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:17 [inline]
> dump_stack+0x194/0x257 lib/dump_stack.c:53
> lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4585
> ireq_opt_deref include/net/inet_sock.h:135 [inline]
> dccp_v4_send_response+0x4b0/0x640 net/dccp/ipv4.c:496
> dccp_v4_conn_request+0x9ee/0x11b0 net/dccp/ipv4.c:633
> dccp_v6_conn_request+0xd30/0x1350 net/dccp/ipv6.c:317
> dccp_rcv_state_process+0x574/0x1620 net/dccp/input.c:612
> dccp_v4_do_rcv+0xeb/0x160 net/dccp/ipv4.c:682
> dccp_v6_do_rcv+0x81a/0x9b0 net/dccp/ipv6.c:578
> sk_backlog_rcv include/net/sock.h:907 [inline]
> __release_sock+0x124/0x360 net/core/sock.c:2274
> release_sock+0xa4/0x2a0 net/core/sock.c:2789
> do_ipv6_setsockopt.isra.9+0x50f/0x38f0 net/ipv6/ipv6_sockglue.c:898
> ipv6_setsockopt+0xd7/0x150 net/ipv6/ipv6_sockglue.c:922
> dccp_setsockopt+0x85/0xd0 net/dccp/proto.c:573
> sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2978
> SYSC_setsockopt net/socket.c:1821 [inline]
> SyS_setsockopt+0x189/0x360 net/socket.c:1800
> entry_SYSCALL_64_fastpath+0x1f/0x96
> RIP: 0033:0x445ec9
> RSP: 002b:00007fa001b58db8 EFLAGS: 00000297 ORIG_RAX: 0000000000000036
> RAX: ffffffffffffffda RBX: 00000000006dbc24 RCX: 0000000000445ec9
> RDX: 0000000000000020 RSI: 0000000000000029 RDI: 0000000000000004
> RBP: 00000000006dbc20 R08: 0000000000000020 R09: 0000000000000000
> R10: 000000002030a000 R11: 0000000000000297 R12: 0000000000000000
> R13: 00007fff809eec1f R14: 00007fa001b599c0 R15: 0000000000000001
syzbot stopped hitting this for some reason, but the bug is still there.
Here's a simplified reproducer that works on Linus' tree as of today:
#include <linux/in.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <unistd.h>
int main()
{
int is_parent = (fork() != 0);
for (;;) {
int fd = socket(AF_INET, SOCK_DCCP, 0);
struct sockaddr_in addr = {
.sin_family = AF_INET,
.sin_port = htobe16(0x4e23),
};
if (is_parent) {
connect(fd, (void *)&addr, sizeof(addr));
} else {
bind(fd, (void *)&addr, sizeof(addr));
listen(fd, 100);
setsockopt(fd, 0, 0xFFFF, NULL, 0);
}
close(fd);
}
}
^ permalink raw reply
* Re: WARNING in kcm_exit_net (2)
From: Eric Biggers @ 2018-04-08 19:38 UTC (permalink / raw)
To: syzbot
Cc: davem, ebiggers, edumazet, linux-kernel, mingo, netdev,
syzkaller-bugs, tom, xiaolou4617, xiyou.wangcong
In-Reply-To: <001a113ed51610bad9055f2d130e@google.com>
On Wed, Nov 29, 2017 at 10:08:01PM -0800, syzbot wrote:
> Hello,
>
> syzkaller hit the following crash on
> 1d3b78bbc6e983fabb3fbf91b76339bf66e4a12c
> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
>
> Unfortunately, I don't have any reproducer for this bug yet.
>
>
> WARNING: CPU: 1 PID: 4099 at net/kcm/kcmsock.c:2014 kcm_exit_net+0x317/0x360
> net/kcm/kcmsock.c:2014
> Kernel panic - not syncing: panic_on_warn set ...
>
> CPU: 1 PID: 4099 Comm: kworker/u4:9 Not tainted 4.14.0+ #129
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Workqueue: netns cleanup_net
> device lo entered promiscuous mode
> Call Trace:
> __dump_stack lib/dump_stack.c:17 [inline]
> dump_stack+0x194/0x257 lib/dump_stack.c:53
> panic+0x1e4/0x41c kernel/panic.c:183
> __warn+0x1dc/0x200 kernel/panic.c:547
> report_bug+0x211/0x2d0 lib/bug.c:184
> fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:177
> fixup_bug arch/x86/kernel/traps.c:246 [inline]
> do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:295
> do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
> invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:926
> RIP: 0010:kcm_exit_net+0x317/0x360 net/kcm/kcmsock.c:2014
> RSP: 0000:ffff8801d9d27198 EFLAGS: 00010293
> RAX: ffff8801c0884540 RBX: 1ffff1003b3a4e33 RCX: ffffffff84a738e7
> RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000286
> RBP: ffff8801d9d27260 R08: 0000000000000003 R09: 1ffff1003b3a4e0c
> R10: ffff8801c0884540 R11: 0000000000000003 R12: 1ffff1003b3a4e37
> R13: ffff8801d9d27238 R14: ffff8801c5fec8a0 R15: ffff8801c4b62e40
> ops_exit_list.isra.6+0xae/0x150 net/core/net_namespace.c:142
> cleanup_net+0x5c7/0xb60 net/core/net_namespace.c:484
> process_one_work+0xbfd/0x1be0 kernel/workqueue.c:2112
> worker_thread+0x223/0x1990 kernel/workqueue.c:2246
> kthread+0x37a/0x440 kernel/kthread.c:238
> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:437
> Dumping ftrace buffer:
> (ftrace buffer empty)
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
>
> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
> Direct all questions to syzkaller@googlegroups.com.
> Please credit me with: Reported-by: syzbot <syzkaller@googlegroups.com>
>
> syzbot will keep track of this bug report.
> Once a fix for this bug is committed, please reply to this email with:
> #syz fix: exact-commit-title
> To mark this as a duplicate of another syzbot report, please reply with:
> #syz dup: exact-subject-of-another-report
> If it's a one-off invalid bug report, please reply with:
> #syz invalid
No reproducer, this last occurred on Dec 26 (103 days ago, commit fba961ab29e),
and there have been several potentially relevant KCM fixes since then such as
581e7226a5d ("kcm: Only allow TCP sockets to be attached to a KCM mux") and
e5571240236 ("kcm: Check if sk_user_data already set in kcm_attach"). So I am
invalidating this for syzbot, but if anyone thinks this may still be a bug then
feel free to look into it.
#syz invalid
Eric
^ permalink raw reply
* Re: WARNING in skb_warn_bad_offload
From: Eric Biggers @ 2018-04-08 19:53 UTC (permalink / raw)
To: syzbot
Cc: Willem de Bruijn, Dmitry Vyukov, David Miller, Jamal Hadi Salim,
Jiří Pírko, LKML, netdev, syzkaller-bugs,
Cong Wang
In-Reply-To: <CACT4Y+ZDRNWj1iRqLvFLjOXJYc2XERWPh+Qa0hNxUgMD1uaeBA@mail.gmail.com>
On Wed, Nov 01, 2017 at 09:50:18PM +0300, 'Dmitry Vyukov' via syzkaller-bugs wrote:
> On Wed, Nov 1, 2017 at 9:48 PM, syzbot
> <bot+abb66e15eb1b298dfe4a13375f18a278d5940e6f@syzkaller.appspotmail.com>
> wrote:
> > Hello,
> >
> > syzkaller hit the following crash on
> > 720bbe532b7c8f5613b48dea627fc58ed9ace707
> > git://git.cmpxchg.org/linux-mmots.git/master
> > compiler: gcc (GCC) 7.1.1 20170620
> > .config is attached
> > Raw console output is attached.
> > C reproducer is attached
> > syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> > for information about syzkaller reproducers
>
>
> This also happens on more recent commits, including linux-next
> 36ef71cae353f88fd6e095e2aaa3e5953af1685d (Oct 20):
>
> syz0: caps=(0x00000400000058c1, 0x0000000000000000) len=4203
> data_len=2810 gso_size=8465 gso_type=3 ip_summed=0
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 3473 at net/core/dev.c:2618
> skb_warn_bad_offload.cold.139+0x224/0x261 net/core/dev.c:2613
> Kernel panic - not syncing: panic_on_warn set ...
>
> CPU: 0 PID: 3473 Comm: a.out Not tainted 4.14.0-rc5-next-20171018 #15
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:16 [inline]
> dump_stack+0x1a8/0x272 lib/dump_stack.c:52
> panic+0x21e/0x4b7 kernel/panic.c:183
> __warn.cold.6+0x182/0x187 kernel/panic.c:546
> report_bug+0x232/0x330 lib/bug.c:183
> fixup_bug+0x3f/0x90 arch/x86/kernel/traps.c:177
> do_trap_no_signal arch/x86/kernel/traps.c:211 [inline]
> do_trap+0x132/0x280 arch/x86/kernel/traps.c:260
> do_error_trap+0x11f/0x390 arch/x86/kernel/traps.c:297
> do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:310
> invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:905
> RIP: 0010:skb_warn_bad_offload.cold.139+0x224/0x261 net/core/dev.c:2613
> RSP: 0018:ffff880064797038 EFLAGS: 00010286
> RAX: 000000000000006f RBX: ffff88006365efe8 RCX: 0000000000000000
> RDX: 000000000000006f RSI: ffffffff815c88c1 RDI: ffffed000c8f2dfd
> RBP: ffff880064797090 R08: ffff8800686f86c0 R09: 0000000000000002
> R10: ffff8800686f86c0 R11: 0000000000000000 R12: ffff8800538b1680
> R13: 0000000000000000 R14: ffff8800538b1680 R15: 0000000000002111
> __skb_gso_segment+0x69e/0x860 net/core/dev.c:2824
> skb_gso_segment include/linux/netdevice.h:3971 [inline]
> validate_xmit_skb+0x29f/0xca0 net/core/dev.c:3074
> validate_xmit_skb_list+0xb7/0x120 net/core/dev.c:3125
> sch_direct_xmit+0x5b5/0x710 net/sched/sch_generic.c:181
> __dev_xmit_skb net/core/dev.c:3206 [inline]
> __dev_queue_xmit+0x1e41/0x2350 net/core/dev.c:3473
> dev_queue_xmit+0x17/0x20 net/core/dev.c:3538
> packet_snd net/packet/af_packet.c:2956 [inline]
> packet_sendmsg+0x487a/0x64b0 net/packet/af_packet.c:2981
> sock_sendmsg_nosec net/socket.c:632 [inline]
> sock_sendmsg+0xd2/0x120 net/socket.c:642
> ___sys_sendmsg+0x7cc/0x900 net/socket.c:2048
> __sys_sendmsg+0xe6/0x220 net/socket.c:2082
> SYSC_sendmsg net/socket.c:2093 [inline]
> SyS_sendmsg+0x36/0x60 net/socket.c:2089
> entry_SYSCALL_64_fastpath+0x1f/0xbe
> RIP: 0033:0x44bab9
> RSP: 002b:00000000007eff18 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 0000000020001046 RCX: 000000000044bab9
> RDX: 0000000000004010 RSI: 00000000207fcfc8 RDI: 0000000000000004
> RBP: 0000000000000086 R08: 850b2da14d2a3706 R09: 0000000000000000
> R10: 1b91126b7f398aaa R11: 0000000000000246 R12: 0000000000000000
> R13: 0000000000407950 R14: 00000000004079e0 R15: 0000000000000000
>
>
>
>
>
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 2986 at net/core/dev.c:2585
> > skb_warn_bad_offload+0x2a9/0x380 net/core/dev.c:2580
> > Kernel panic - not syncing: panic_on_warn set ...
> >
> > CPU: 0 PID: 2986 Comm: syzkaller546001 Not tainted 4.13.0-mm1+ #7
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > Google 01/01/2011
> > Call Trace:
> > __dump_stack lib/dump_stack.c:16 [inline]
> > dump_stack+0x194/0x257 lib/dump_stack.c:52
> > panic+0x1e4/0x417 kernel/panic.c:181
> > __warn+0x1c4/0x1d9 kernel/panic.c:542
> > report_bug+0x211/0x2d0 lib/bug.c:183
> > fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:178
> > do_trap_no_signal arch/x86/kernel/traps.c:212 [inline]
> > do_trap+0x260/0x390 arch/x86/kernel/traps.c:261
> > do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:298
> > do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:311
> > invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:905
> > RIP: 0010:skb_warn_bad_offload+0x2a9/0x380 net/core/dev.c:2580
> > RSP: 0018:ffff8801ce73f0a0 EFLAGS: 00010282
> > RAX: 000000000000006f RBX: ffff8801cd84cde0 RCX: 0000000000000000
> > RDX: 000000000000006f RSI: 1ffff10039ce7dd4 RDI: ffffed0039ce7e08
> > RBP: ffff8801ce73f0f8 R08: ffff8801ce73e790 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ce7802c0
> > R13: 0000000000000000 R14: ffff8801ce7802c0 R15: 0000000000002111
> > __skb_gso_segment+0x607/0x7f0 net/core/dev.c:2791
> > skb_gso_segment include/linux/netdevice.h:3951 [inline]
> > validate_xmit_skb+0x4ba/0xb20 net/core/dev.c:3041
> > validate_xmit_skb_list+0xb7/0x120 net/core/dev.c:3092
> > sch_direct_xmit+0x3b6/0x6d0 net/sched/sch_generic.c:181
> > __dev_xmit_skb net/core/dev.c:3173 [inline]
> > __dev_queue_xmit+0x15fe/0x1e40 net/core/dev.c:3440
> > dev_queue_xmit+0x17/0x20 net/core/dev.c:3505
> > packet_snd net/packet/af_packet.c:2950 [inline]
> > packet_sendmsg+0x3bbf/0x6030 net/packet/af_packet.c:2975
> > sock_sendmsg_nosec net/socket.c:633 [inline]
> > sock_sendmsg+0xca/0x110 net/socket.c:643
> > ___sys_sendmsg+0x75b/0x8a0 net/socket.c:2049
> > __sys_sendmsg+0xe5/0x210 net/socket.c:2083
> > SYSC_sendmsg net/socket.c:2094 [inline]
> > SyS_sendmsg+0x2d/0x50 net/socket.c:2090
> > entry_SYSCALL_64_fastpath+0x1f/0xbe
> > RIP: 0033:0x445489
> > RSP: 002b:00000000007efe68 EFLAGS: 00000217 ORIG_RAX: 000000000000002e
> > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000445489
> > RDX: 0000000000004010 RSI: 00000000207fcfc8 RDI: 0000000000000004
> > RBP: 0000000000000082 R08: 000000000000cdf3 R09: 000000000000cdf3
> > R10: 0000000000000004 R11: 0000000000000217 R12: 0000000000402ae0
> > R13: 0000000000402b70 R14: 0000000000000000 R15: 0000000000000000
> > Dumping ftrace buffer:
> > (ftrace buffer empty)
> > Kernel Offset: disabled
> > Rebooting in 86400 seconds..
> >
> >
> > ---
> > This bug is generated by a dumb bot. It may contain errors.
> > See https://goo.gl/tpsmEJ for details.
> > Direct all questions to syzkaller@googlegroups.com.
> > Please credit me with: Reported-by: syzbot <syzkaller@googlegroups.com>
> >
> > syzbot will keep track of this bug report.
> > Once a fix for this bug is committed, please reply to this email with:
> > #syz fix: exact-commit-title
Apparently fixed by commit 8d74e9f88d65a, so telling syzbot:
#syz fix: net: avoid skb_warn_bad_offload on IS_ERR
- Eric
^ permalink raw reply
* [PATCH v3] dp83640: Ensure against premature access to PHY registers after reset
From: Esben Haabendal @ 2018-04-08 20:17 UTC (permalink / raw)
To: netdev
Cc: Esben Haabendal, Richard Cochran, Andrew Lunn, Florian Fainelli,
linux-kernel
In-Reply-To: <20180406170844.4248-1-esben.haabendal@gmail.com>
From: Esben Haabendal <eha@deif.com>
The datasheet specifies a 3uS pause after performing a software
reset. The default implementation of genphy_soft_reset() does not
provide this, so implement soft_reset with the needed pause.
Signed-off-by: Esben Haabendal <eha@deif.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
drivers/net/phy/dp83640.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/drivers/net/phy/dp83640.c b/drivers/net/phy/dp83640.c
index 654f42d00092..a6c87793d899 100644
--- a/drivers/net/phy/dp83640.c
+++ b/drivers/net/phy/dp83640.c
@@ -1207,6 +1207,23 @@ static void dp83640_remove(struct phy_device *phydev)
kfree(dp83640);
}
+static int dp83640_soft_reset(struct phy_device *phydev)
+{
+ int ret;
+
+ ret = genphy_soft_reset(phydev);
+ if (ret < 0)
+ return ret;
+
+ /* From DP83640 datasheet: "Software driver code must wait 3 us
+ * following a software reset before allowing further serial MII
+ * operations with the DP83640."
+ */
+ udelay(10); /* Taking udelay inaccuracy into account */
+
+ return 0;
+}
+
static int dp83640_config_init(struct phy_device *phydev)
{
struct dp83640_private *dp83640 = phydev->priv;
@@ -1501,6 +1518,7 @@ static struct phy_driver dp83640_driver = {
.flags = PHY_HAS_INTERRUPT,
.probe = dp83640_probe,
.remove = dp83640_remove,
+ .soft_reset = dp83640_soft_reset,
.config_init = dp83640_config_init,
.ack_interrupt = dp83640_ack_interrupt,
.config_intr = dp83640_config_intr,
--
2.16.3
^ permalink raw reply related
* Re: [PATCH bpf-next v8 05/11] seccomp,landlock: Enforce Landlock programs per process hierarchy
From: Andy Lutomirski @ 2018-04-08 21:06 UTC (permalink / raw)
To: Mickaël Salaün
Cc: Andy Lutomirski, Alexei Starovoitov, Daniel Borkmann, LKML,
Alexei Starovoitov, Arnaldo Carvalho de Melo, Casey Schaufler,
David Drysdale, David S . Miller, Eric W . Biederman, Jann Horn,
Jonathan Corbet, Michael Kerrisk, Kees Cook, Paul Moore,
Sargun Dhillon, Serge E . Hallyn, Shuah Khan, Tejun Heo,
Thomas Graf, Tycho Andersen, Will Drewry, Kernel Hardening,
Linux
In-Reply-To: <498f8193-c909-78b2-e4ca-c1dd05605255@digikod.net>
On Sun, Apr 8, 2018 at 6:13 AM, Mickaël Salaün <mic@digikod.net> wrote:
>
> On 02/27/2018 10:48 PM, Mickaël Salaün wrote:
>>
>> On 27/02/2018 17:39, Andy Lutomirski wrote:
>>> On Tue, Feb 27, 2018 at 5:32 AM, Alexei Starovoitov
>>> <alexei.starovoitov@gmail.com> wrote:
>>>> On Tue, Feb 27, 2018 at 05:20:55AM +0000, Andy Lutomirski wrote:
>>>>> On Tue, Feb 27, 2018 at 4:54 AM, Alexei Starovoitov
>>>>> <alexei.starovoitov@gmail.com> wrote:
>>>>>> On Tue, Feb 27, 2018 at 04:40:34AM +0000, Andy Lutomirski wrote:
>>>>>>> On Tue, Feb 27, 2018 at 2:08 AM, Alexei Starovoitov
>>>>>>> <alexei.starovoitov@gmail.com> wrote:
>>>>>>>> On Tue, Feb 27, 2018 at 01:41:15AM +0100, Mickaël Salaün wrote:
>>>>>>>>> The seccomp(2) syscall can be used by a task to apply a Landlock program
>>>>>>>>> to itself. As a seccomp filter, a Landlock program is enforced for the
>>>>>>>>> current task and all its future children. A program is immutable and a
>>>>>>>>> task can only add new restricting programs to itself, forming a list of
>>>>>>>>> programss.
>>>>>>>>>
>>>>>>>>> A Landlock program is tied to a Landlock hook. If the action on a kernel
>>>>>>>>> object is allowed by the other Linux security mechanisms (e.g. DAC,
>>>>>>>>> capabilities, other LSM), then a Landlock hook related to this kind of
>>>>>>>>> object is triggered. The list of programs for this hook is then
>>>>>>>>> evaluated. Each program return a 32-bit value which can deny the action
>>>>>>>>> on a kernel object with a non-zero value. If every programs of the list
>>>>>>>>> return zero, then the action on the object is allowed.
>>>>>>>>>
>>>>>>>>> Multiple Landlock programs can be chained to share a 64-bits value for a
>>>>>>>>> call chain (e.g. evaluating multiple elements of a file path). This
>>>>>>>>> chaining is restricted when a process construct this chain by loading a
>>>>>>>>> program, but additional checks are performed when it requests to apply
>>>>>>>>> this chain of programs to itself. The restrictions ensure that it is
>>>>>>>>> not possible to call multiple programs in a way that would imply to
>>>>>>>>> handle multiple shared values (i.e. cookies) for one chain. For now,
>>>>>>>>> only a fs_pick program can be chained to the same type of program,
>>>>>>>>> because it may make sense if they have different triggers (cf. next
>>>>>>>>> commits). This restrictions still allows to reuse Landlock programs in
>>>>>>>>> a safe way (e.g. use the same loaded fs_walk program with multiple
>>>>>>>>> chains of fs_pick programs).
>>>>>>>>>
>>>>>>>>> Signed-off-by: Mickaël Salaün <mic@digikod.net>
>>>>>>>>
>>>>>>>> ...
>>>>>>>>
>>>>>>>>> +struct landlock_prog_set *landlock_prepend_prog(
>>>>>>>>> + struct landlock_prog_set *current_prog_set,
>>>>>>>>> + struct bpf_prog *prog)
>>>>>>>>> +{
>>>>>>>>> + struct landlock_prog_set *new_prog_set = current_prog_set;
>>>>>>>>> + unsigned long pages;
>>>>>>>>> + int err;
>>>>>>>>> + size_t i;
>>>>>>>>> + struct landlock_prog_set tmp_prog_set = {};
>>>>>>>>> +
>>>>>>>>> + if (prog->type != BPF_PROG_TYPE_LANDLOCK_HOOK)
>>>>>>>>> + return ERR_PTR(-EINVAL);
>>>>>>>>> +
>>>>>>>>> + /* validate memory size allocation */
>>>>>>>>> + pages = prog->pages;
>>>>>>>>> + if (current_prog_set) {
>>>>>>>>> + size_t i;
>>>>>>>>> +
>>>>>>>>> + for (i = 0; i < ARRAY_SIZE(current_prog_set->programs); i++) {
>>>>>>>>> + struct landlock_prog_list *walker_p;
>>>>>>>>> +
>>>>>>>>> + for (walker_p = current_prog_set->programs[i];
>>>>>>>>> + walker_p; walker_p = walker_p->prev)
>>>>>>>>> + pages += walker_p->prog->pages;
>>>>>>>>> + }
>>>>>>>>> + /* count a struct landlock_prog_set if we need to allocate one */
>>>>>>>>> + if (refcount_read(¤t_prog_set->usage) != 1)
>>>>>>>>> + pages += round_up(sizeof(*current_prog_set), PAGE_SIZE)
>>>>>>>>> + / PAGE_SIZE;
>>>>>>>>> + }
>>>>>>>>> + if (pages > LANDLOCK_PROGRAMS_MAX_PAGES)
>>>>>>>>> + return ERR_PTR(-E2BIG);
>>>>>>>>> +
>>>>>>>>> + /* ensure early that we can allocate enough memory for the new
>>>>>>>>> + * prog_lists */
>>>>>>>>> + err = store_landlock_prog(&tmp_prog_set, current_prog_set, prog);
>>>>>>>>> + if (err)
>>>>>>>>> + return ERR_PTR(err);
>>>>>>>>> +
>>>>>>>>> + /*
>>>>>>>>> + * Each task_struct points to an array of prog list pointers. These
>>>>>>>>> + * tables are duplicated when additions are made (which means each
>>>>>>>>> + * table needs to be refcounted for the processes using it). When a new
>>>>>>>>> + * table is created, all the refcounters on the prog_list are bumped (to
>>>>>>>>> + * track each table that references the prog). When a new prog is
>>>>>>>>> + * added, it's just prepended to the list for the new table to point
>>>>>>>>> + * at.
>>>>>>>>> + *
>>>>>>>>> + * Manage all the possible errors before this step to not uselessly
>>>>>>>>> + * duplicate current_prog_set and avoid a rollback.
>>>>>>>>> + */
>>>>>>>>> + if (!new_prog_set) {
>>>>>>>>> + /*
>>>>>>>>> + * If there is no Landlock program set used by the current task,
>>>>>>>>> + * then create a new one.
>>>>>>>>> + */
>>>>>>>>> + new_prog_set = new_landlock_prog_set();
>>>>>>>>> + if (IS_ERR(new_prog_set))
>>>>>>>>> + goto put_tmp_lists;
>>>>>>>>> + } else if (refcount_read(¤t_prog_set->usage) > 1) {
>>>>>>>>> + /*
>>>>>>>>> + * If the current task is not the sole user of its Landlock
>>>>>>>>> + * program set, then duplicate them.
>>>>>>>>> + */
>>>>>>>>> + new_prog_set = new_landlock_prog_set();
>>>>>>>>> + if (IS_ERR(new_prog_set))
>>>>>>>>> + goto put_tmp_lists;
>>>>>>>>> + for (i = 0; i < ARRAY_SIZE(new_prog_set->programs); i++) {
>>>>>>>>> + new_prog_set->programs[i] =
>>>>>>>>> + READ_ONCE(current_prog_set->programs[i]);
>>>>>>>>> + if (new_prog_set->programs[i])
>>>>>>>>> + refcount_inc(&new_prog_set->programs[i]->usage);
>>>>>>>>> + }
>>>>>>>>> +
>>>>>>>>> + /*
>>>>>>>>> + * Landlock program set from the current task will not be freed
>>>>>>>>> + * here because the usage is strictly greater than 1. It is
>>>>>>>>> + * only prevented to be freed by another task thanks to the
>>>>>>>>> + * caller of landlock_prepend_prog() which should be locked if
>>>>>>>>> + * needed.
>>>>>>>>> + */
>>>>>>>>> + landlock_put_prog_set(current_prog_set);
>>>>>>>>> + }
>>>>>>>>> +
>>>>>>>>> + /* prepend tmp_prog_set to new_prog_set */
>>>>>>>>> + for (i = 0; i < ARRAY_SIZE(tmp_prog_set.programs); i++) {
>>>>>>>>> + /* get the last new list */
>>>>>>>>> + struct landlock_prog_list *last_list =
>>>>>>>>> + tmp_prog_set.programs[i];
>>>>>>>>> +
>>>>>>>>> + if (last_list) {
>>>>>>>>> + while (last_list->prev)
>>>>>>>>> + last_list = last_list->prev;
>>>>>>>>> + /* no need to increment usage (pointer replacement) */
>>>>>>>>> + last_list->prev = new_prog_set->programs[i];
>>>>>>>>> + new_prog_set->programs[i] = tmp_prog_set.programs[i];
>>>>>>>>> + }
>>>>>>>>> + }
>>>>>>>>> + new_prog_set->chain_last = tmp_prog_set.chain_last;
>>>>>>>>> + return new_prog_set;
>>>>>>>>> +
>>>>>>>>> +put_tmp_lists:
>>>>>>>>> + for (i = 0; i < ARRAY_SIZE(tmp_prog_set.programs); i++)
>>>>>>>>> + put_landlock_prog_list(tmp_prog_set.programs[i]);
>>>>>>>>> + return new_prog_set;
>>>>>>>>> +}
>>>>>>>>
>>>>>>>> Nack on the chaining concept.
>>>>>>>> Please do not reinvent the wheel.
>>>>>>>> There is an existing mechanism for attaching/detaching/quering multiple
>>>>>>>> programs attached to cgroup and tracing hooks that are also
>>>>>>>> efficiently executed via BPF_PROG_RUN_ARRAY.
>>>>>>>> Please use that instead.
>>>>>>>>
>>>>>>>
>>>>>>> I don't see how that would help. Suppose you add a filter, then
>>>>>>> fork(), and then the child adds another filter. Do you want to
>>>>>>> duplicate the entire array? You certainly can't *modify* the array
>>>>>>> because you'll affect processes that shouldn't be affected.
>>>>>>>
>>>>>>> In contrast, doing this through seccomp like the earlier patches
>>>>>>> seemed just fine to me, and seccomp already had the right logic.
>>>>>>
>>>>>> it doesn't look to me that existing seccomp side of managing fork
>>>>>> situation can be reused. Here there is an attempt to add 'chaining'
>>>>>> concept which sort of an extension of existing seccomp style,
>>>>>> but somehow heavily done on bpf side and contradicts cgroup/tracing.
>>>>>>
>>>>>
>>>>> I don't see why the seccomp way can't be used. I agree with you that
>>>>> the seccomp *style* shouldn't be used in bpf code like this, but I
>>>>> think that Landlock programs can and should just live in the existing
>>>>> seccomp chain. If the existing seccomp code needs some modification
>>>>> to make this work, then so be it.
>>>>
>>>> +1
>>>> if that was the case...
>>>> but that's not my reading of the patch set.
>>>
>>> An earlier version of the patch set used the seccomp filter chain.
>>> Mickaël, what exactly was wrong with that approach other than that the
>>> seccomp() syscall was awkward for you to use? You could add a
>>> seccomp_add_landlock_rule() syscall if you needed to.
>>
>> Nothing was wrong about about that, this part did not changed (see my
>> next comment).
>>
>>>
>>> As a side comment, why is this an LSM at all, let alone a non-stacking
>>> LSM? It would make a lot more sense to me to make Landlock depend on
>>> having LSMs configured in but to call the landlock hooks directly from
>>> the security_xyz() hooks.
>>
>> See Casey's answer and his patch series: https://lwn.net/Articles/741963/
>>
>>>
>>>>
>>>>> In other words, the kernel already has two kinds of chaining:
>>>>> seccomp's and bpf's. bpf's doesn't work right for this type of usage
>>>>> across fork(), whereas seccomp's already handles that case correctly.
>>>>> (In contrast, seccomp's is totally wrong for cgroup-attached filters.)
>>>>> So IMO Landlock should use the seccomp core code and call into bpf
>>>>> for the actual filtering.
>>>>
>>>> +1
>>>> in cgroup we had to invent this new BPF_PROG_RUN_ARRAY mechanism,
>>>> since cgroup hierarchy can be complicated with bpf progs attached
>>>> at different levels with different override/multiprog properties,
>>>> so walking link list and checking all flags at run-time would have
>>>> been too slow. That's why we added compute_effective_progs().
>>>
>>> If we start adding override flags to Landlock, I think we're doing it
>>> wrong. With cgroup bpf programs, the whole mess is set up by the
>>> administrator. With seccomp, and with Landlock if done correctly, it
>>> *won't* be set up by the administrator, so the chance that everyone
>>> gets all the flags right is about zero. All attached filters should
>>> run unconditionally.
>>
>>
>> There is a misunderstanding about this chaining mechanism. This should
>> not be confused with the list of seccomp filters nor the cgroup
>> hierarchies. Landlock programs can be stacked the same way seccomp's
>> filters can (cf. struct landlock_prog_set, the "chain_last" field is an
>> optimization which is not used for this struct handling). This stackable
>> property did not changed from the previous patch series. The chaining
>> mechanism is for another use case, which does not make sense for seccomp
>> filters nor other eBPF program types, at least for now, from what I can
>> tell.
>>
>> You may want to get a look at my talk at FOSDEM
>> (https://landlock.io/talks/2018-02-04_landlock-fosdem.pdf), especially
>> slides 11 and 12.
>>
>> Let me explain my reasoning about this program chaining thing.
>>
>> To check if an action on a file is allowed, we first need to identify
>> this file and match it to the security policy. In a previous
>> (non-public) patch series, I tried to use one type of eBPF program to
>> check every kind of access to a file. To be able to identify a file, I
>> relied on an eBPF map, similar to the current inode map. This map store
>> a set of references to file descriptors. I then created a function
>> bpf_is_file_beneath() to check if the requested file was beneath a file
>> in the map. This way, no chaining, only one eBPF program type to check
>> an access to a file... but some issues then emerged. First, this design
>> create a side-channel which help an attacker using such a program to
>> infer some information not normally available, for example to get a hint
>> on where a file descriptor (received from a UNIX socket) come from.
>> Another issue is that this type of program would be called for each
>> component of a path. Indeed, when the kernel check if an access to a
>> file is allowed, it walk through all of the directories in its path
>> (checking if the current process is allowed to execute them). That first
>> attempt led me to rethink the way we could filter an access to a file
>> *path*.
>>
>> To minimize the number of called to an eBPF program dedicated to
>> validate an access to a file path, I decided to create three subtype of
>> eBPF programs. The FS_WALK type is called when walking through every
>> directory of a file path (except the last one if it is the target). We
>> can then restrict this type of program to the minimum set of functions
>> it is allowed to call and the minimum set of data available from its
>> context. The first implicit chaining is for this type of program. To be
>> able to evaluate a path while being called for all its components, this
>> program need to store a state (to remember what was the parent directory
>> of this path). There is no "previous" field in the subtype for this
>> program because it is chained with itself, for each directories. This
>> enable to create a FS_WALK program to evaluate a file hierarchy, thank
>> to the inode map which can be used to check if a directory of this
>> hierarchy is part of an allowed (or denied) list of directories. This
>> design enables to express a file hierarchy in a programmatic way,
>> without requiring an eBPF helper to do the job (unlike my first experiment).
>>
>> The explicit chaining is used to tied a path evaluation (with a FS_WALK
>> program) to an access to the actual file being requested (the last
>> component of a file path), with a FS_PICK program. It is only at this
>> time that the kernel check for the requested action (e.g. read, write,
>> chdir, append...). To be able to filter such access request we can have
>> one call to the same program for every action and let this program check
>> for which action it was called. However, this design does not allow the
>> kernel to know if the current action is indeed handled by this program.
>> Hence, it is not possible to implement a cache mechanism to only call
>> this program if it knows how to handle this action.
>>
>> The approach I took for this FS_PICK type of program is to add to its
>> subtype which action it can handle (with the "triggers" bitfield, seen
>> as ORed actions). This way, the kernel knows if a call to a FS_PICK
>> program is necessary. If the user wants to enforce a different security
>> policy according to the action requested on a file, then it needs
>> multiple FS_PICK programs. However, to reduce the number of such
>> programs, this patch series allow a FS_PICK program to be chained with
>> another, the same way a FS_WALK is chained with itself. This way, if the
>> user want to check if the action is a for example an "open" and a "read"
>> and not a "map" and a "read", then it can chain multiple FS_PICK
>> programs with different triggers actions. The OR check performed by the
>> kernel is not a limitation then, only a way to know if a call to an eBPF
>> program is needed.
>>
>> The last type of program is FS_GET. This one is called when a process
>> get a struct file or change its working directory. This is the only
>> program type able (and allowed) to tag a file. This restriction is
>> important to not being subject to resource exhaustion attacks (i.e.
>> tagging every inode accessible to an attacker, which would allocate too
>> much kernel memory).
>>
>> This design gives room for improvements to create a cache of eBPF
>> context (input data, including maps if any), with the result of an eBPF
>> program. This would help limit the number of call to an eBPF program the
>> same way SELinux or other kernel components do to limit costly checks.
>>
>> The eBPF maps of progs are useful to call the same type of eBPF
>> program. It does not fit with this use case because we may want multiple
>> eBPF program according to the action requested on a kernel object (e.g.
>> FS_GET). The other reason is because the eBPF program does not know what
>> will be the next (type of) access check performed by the kernel.
>>
>> To say it another way, this chaining mechanism is a way to split a
>> kernel object evaluation with multiple specialized programs, each of
>> them being able to deal with data tied to their type. Using a monolithic
>> eBPF program to check everything does not scale and does not fit with
>> unprivileged use either.
>>
>> As a side note, the cookie value is only an ephemeral value to keep a
>> state between multiple programs call. It can be used to create a state
>> machine for an object evaluation.
>>
>> I don't see a way to do an efficient and programmatic path evaluation,
>> with different access checks, with the current eBPF features. Please let
>> me know if you know how to do it another way.
>>
>
> Andy, Alexei, Daniel, what do you think about this Landlock program
> chaining and cookie?
>
Can you give a small pseudocode real world example that acutally needs
chaining? The mechanism is quite complicated and I'd like to
understand how it'll be used.
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