linux-toradex.git/kernel/bpf, branch v5.8-rc6 Linux kernel for Apalis and Colibri modules Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-07-11T01:16:22+00:00 Linus Torvalds torvalds@linux-foundation.org 2020-07-11T01:16:22+00:00 5a764898afec0bc097003e8c3e727792289f76d6 Pull networking fixes from David Miller: 1) Restore previous behavior of CAP_SYS_ADMIN wrt loading networking BPF programs, from Maciej Żenczykowski. 2) Fix dropped broadcasts in mac80211 code, from Seevalamuthu Mariappan. 3) Slay memory leak in nl80211 bss color attribute parsing code, from Luca Coelho. 4) Get route from skb properly in ip_route_use_hint(), from Miaohe Lin. 5) Don't allow anything other than ARPHRD_ETHER in llc code, from Eric Dumazet. 6) xsk code dips too deeply into DMA mapping implementation internals. Add dma_need_sync and use it. From Christoph Hellwig 7) Enforce power-of-2 for BPF ringbuf sizes. From Andrii Nakryiko. 8) Check for disallowed attributes when loading flow dissector BPF programs. From Lorenz Bauer. 9) Correct packet injection to L3 tunnel devices via AF_PACKET, from Jason A. Donenfeld. 10) Don't advertise checksum offload on ipa devices that don't support it. From Alex Elder. 11) Resolve several issues in TCP MD5 signature support. Missing memory barriers, bogus options emitted when using syncookies, and failure to allow md5 key changes in established states. All from Eric Dumazet. 12) Fix interface leak in hsr code, from Taehee Yoo. 13) VF reset fixes in hns3 driver, from Huazhong Tan. 14) Make loopback work again with ipv6 anycast, from David Ahern. 15) Fix TX starvation under high load in fec driver, from Tobias Waldekranz. 16) MLD2 payload lengths not checked properly in bridge multicast code, from Linus Lüssing. 17) Packet scheduler code that wants to find the inner protocol currently only works for one level of VLAN encapsulation. Allow Q-in-Q situations to work properly here, from Toke Høiland-Jørgensen. 18) Fix route leak in l2tp, from Xin Long. 19) Resolve conflict between the sk->sk_user_data usage of bpf reuseport support and various protocols. From Martin KaFai Lau. 20) Fix socket cgroup v2 reference counting in some situations, from Cong Wang. 21) Cure memory leak in mlx5 connection tracking offload support, from Eli Britstein. * git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (146 commits) mlxsw: pci: Fix use-after-free in case of failed devlink reload mlxsw: spectrum_router: Remove inappropriate usage of WARN_ON() net: macb: fix call to pm_runtime in the suspend/resume functions net: macb: fix macb_suspend() by removing call to netif_carrier_off() net: macb: fix macb_get/set_wol() when moving to phylink net: macb: mark device wake capable when "magic-packet" property present net: macb: fix wakeup test in runtime suspend/resume routines bnxt_en: fix NULL dereference in case SR-IOV configuration fails libbpf: Fix libbpf hashmap on (I)LP32 architectures net/mlx5e: CT: Fix memory leak in cleanup net/mlx5e: Fix port buffers cell size value net/mlx5e: Fix 50G per lane indication net/mlx5e: Fix CPU mapping after function reload to avoid aRFS RX crash net/mlx5e: Fix VXLAN configuration restore after function reload net/mlx5e: Fix usage of rcu-protected pointer net/mxl5e: Verify that rpriv is not NULL net/mlx5: E-Switch, Fix vlan or qos setting in legacy mode net/mlx5: Fix eeprom support for SFP module cgroup: Fix sock_cgroup_data on big-endian. selftests: bpf: Fix detach from sockmap tests ... 
Pull networking fixes from David Miller:

 1) Restore previous behavior of CAP_SYS_ADMIN wrt loading networking
    BPF programs, from Maciej Żenczykowski.

 2) Fix dropped broadcasts in mac80211 code, from Seevalamuthu
    Mariappan.

 3) Slay memory leak in nl80211 bss color attribute parsing code, from
    Luca Coelho.

 4) Get route from skb properly in ip_route_use_hint(), from Miaohe Lin.

 5) Don't allow anything other than ARPHRD_ETHER in llc code, from Eric
    Dumazet.

 6) xsk code dips too deeply into DMA mapping implementation internals.
    Add dma_need_sync and use it. From Christoph Hellwig

 7) Enforce power-of-2 for BPF ringbuf sizes. From Andrii Nakryiko.

 8) Check for disallowed attributes when loading flow dissector BPF
    programs. From Lorenz Bauer.

 9) Correct packet injection to L3 tunnel devices via AF_PACKET, from
    Jason A. Donenfeld.

10) Don't advertise checksum offload on ipa devices that don't support
    it. From Alex Elder.

11) Resolve several issues in TCP MD5 signature support. Missing memory
    barriers, bogus options emitted when using syncookies, and failure
    to allow md5 key changes in established states. All from Eric
    Dumazet.

12) Fix interface leak in hsr code, from Taehee Yoo.

13) VF reset fixes in hns3 driver, from Huazhong Tan.

14) Make loopback work again with ipv6 anycast, from David Ahern.

15) Fix TX starvation under high load in fec driver, from Tobias
    Waldekranz.

16) MLD2 payload lengths not checked properly in bridge multicast code,
    from Linus Lüssing.

17) Packet scheduler code that wants to find the inner protocol
    currently only works for one level of VLAN encapsulation. Allow
    Q-in-Q situations to work properly here, from Toke
    Høiland-Jørgensen.

18) Fix route leak in l2tp, from Xin Long.

19) Resolve conflict between the sk->sk_user_data usage of bpf reuseport
    support and various protocols. From Martin KaFai Lau.

20) Fix socket cgroup v2 reference counting in some situations, from
    Cong Wang.

21) Cure memory leak in mlx5 connection tracking offload support, from
    Eli Britstein.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (146 commits)
  mlxsw: pci: Fix use-after-free in case of failed devlink reload
  mlxsw: spectrum_router: Remove inappropriate usage of WARN_ON()
  net: macb: fix call to pm_runtime in the suspend/resume functions
  net: macb: fix macb_suspend() by removing call to netif_carrier_off()
  net: macb: fix macb_get/set_wol() when moving to phylink
  net: macb: mark device wake capable when "magic-packet" property present
  net: macb: fix wakeup test in runtime suspend/resume routines
  bnxt_en: fix NULL dereference in case SR-IOV configuration fails
  libbpf: Fix libbpf hashmap on (I)LP32 architectures
  net/mlx5e: CT: Fix memory leak in cleanup
  net/mlx5e: Fix port buffers cell size value
  net/mlx5e: Fix 50G per lane indication
  net/mlx5e: Fix CPU mapping after function reload to avoid aRFS RX crash
  net/mlx5e: Fix VXLAN configuration restore after function reload
  net/mlx5e: Fix usage of rcu-protected pointer
  net/mxl5e: Verify that rpriv is not NULL
  net/mlx5: E-Switch, Fix vlan or qos setting in legacy mode
  net/mlx5: Fix eeprom support for SFP module
  cgroup: Fix sock_cgroup_data on big-endian.
  selftests: bpf: Fix detach from sockmap tests
  ...
Merge tag 'kallsyms_show_value-v5.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux 2020-07-09T20:09:30+00:00 Linus Torvalds torvalds@linux-foundation.org 2020-07-09T20:09:30+00:00 ce69fb3b392fbfd6c255aeb0ee371652478c716f Pull kallsyms fix from Kees Cook: "Refactor kallsyms_show_value() users for correct cred. I'm not delighted by the timing of getting these changes to you, but it does fix a handful of kernel address exposures, and no one has screamed yet at the patches. Several users of kallsyms_show_value() were performing checks not during "open". Refactor everything needed to gain proper checks against file->f_cred for modules, kprobes, and bpf" * tag 'kallsyms_show_value-v5.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: selftests: kmod: Add module address visibility test bpf: Check correct cred for CAP_SYSLOG in bpf_dump_raw_ok() kprobes: Do not expose probe addresses to non-CAP_SYSLOG module: Do not expose section addresses to non-CAP_SYSLOG module: Refactor section attr into bin attribute kallsyms: Refactor kallsyms_show_value() to take cred 
Pull kallsyms fix from Kees Cook:
 "Refactor kallsyms_show_value() users for correct cred.

  I'm not delighted by the timing of getting these changes to you, but
  it does fix a handful of kernel address exposures, and no one has
  screamed yet at the patches.

  Several users of kallsyms_show_value() were performing checks not
  during "open". Refactor everything needed to gain proper checks
  against file->f_cred for modules, kprobes, and bpf"

* tag 'kallsyms_show_value-v5.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  selftests: kmod: Add module address visibility test
  bpf: Check correct cred for CAP_SYSLOG in bpf_dump_raw_ok()
  kprobes: Do not expose probe addresses to non-CAP_SYSLOG
  module: Do not expose section addresses to non-CAP_SYSLOG
  module: Refactor section attr into bin attribute
  kallsyms: Refactor kallsyms_show_value() to take cred
bpf: net: Avoid incorrect bpf_sk_reuseport_detach call 2020-07-09T20:03:31+00:00 Martin KaFai Lau kafai@fb.com 2020-07-09T06:11:10+00:00 c9a368f1c0fbe2e3a21ebf231caeae58b18b2681 bpf_sk_reuseport_detach is currently called when sk->sk_user_data is not NULL. It is incorrect because sk->sk_user_data may not be managed by the bpf's reuseport_array. It has been reported in [1] that, the bpf_sk_reuseport_detach() which is called from udp_lib_unhash() has corrupted the sk_user_data managed by l2tp. This patch solves it by using another bit (defined as SK_USER_DATA_BPF) of the sk_user_data pointer value. It marks that a sk_user_data is managed/owned by BPF. The patch depends on a PTRMASK introduced in commit f1ff5ce2cd5e ("net, sk_msg: Clear sk_user_data pointer on clone if tagged"). [ Note: sk->sk_user_data is used by bpf's reuseport_array only when a sk is added to the bpf's reuseport_array. i.e. doing setsockopt(SO_REUSEPORT) and having "sk->sk_reuseport == 1" alone will not stop sk->sk_user_data being used by other means. ] [1]: https://lore.kernel.org/netdev/20200706121259.GA20199@katalix.com/ Fixes: 5dc4c4b7d4e8 ("bpf: Introduce BPF_MAP_TYPE_REUSEPORT_SOCKARRAY") Reported-by: James Chapman <jchapman@katalix.com> Reported-by: syzbot+9f092552ba9a5efca5df@syzkaller.appspotmail.com Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: James Chapman <jchapman@katalix.com> Acked-by: James Chapman <jchapman@katalix.com> Link: https://lore.kernel.org/bpf/20200709061110.4019316-1-kafai@fb.com 
bpf_sk_reuseport_detach is currently called when sk->sk_user_data
is not NULL.  It is incorrect because sk->sk_user_data may not be
managed by the bpf's reuseport_array.  It has been reported in [1] that,
the bpf_sk_reuseport_detach() which is called from udp_lib_unhash() has
corrupted the sk_user_data managed by l2tp.

This patch solves it by using another bit (defined as SK_USER_DATA_BPF)
of the sk_user_data pointer value.  It marks that a sk_user_data is
managed/owned by BPF.

The patch depends on a PTRMASK introduced in
commit f1ff5ce2cd5e ("net, sk_msg: Clear sk_user_data pointer on clone if tagged").

[ Note: sk->sk_user_data is used by bpf's reuseport_array only when a sk is
  added to the bpf's reuseport_array.
  i.e. doing setsockopt(SO_REUSEPORT) and having "sk->sk_reuseport == 1"
  alone will not stop sk->sk_user_data being used by other means. ]

[1]: https://lore.kernel.org/netdev/20200706121259.GA20199@katalix.com/

Fixes: 5dc4c4b7d4e8 ("bpf: Introduce BPF_MAP_TYPE_REUSEPORT_SOCKARRAY")
Reported-by: James Chapman <jchapman@katalix.com>
Reported-by: syzbot+9f092552ba9a5efca5df@syzkaller.appspotmail.com
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: James Chapman <jchapman@katalix.com>
Acked-by: James Chapman <jchapman@katalix.com>
Link: https://lore.kernel.org/bpf/20200709061110.4019316-1-kafai@fb.com
bpf: net: Avoid copying sk_user_data of reuseport_array during sk_clone 2020-07-09T20:03:31+00:00 Martin KaFai Lau kafai@fb.com 2020-07-09T06:11:04+00:00 f3dda7a679df183e798b86e7b6ec05ab35476de3 It makes little sense for copying sk_user_data of reuseport_array during sk_clone_lock(). This patch reuses the SK_USER_DATA_NOCOPY bit introduced in commit f1ff5ce2cd5e ("net, sk_msg: Clear sk_user_data pointer on clone if tagged"). It is used to mark the sk_user_data is not supposed to be copied to its clone. Although the cloned sk's sk_user_data will not be used/freed in bpf_sk_reuseport_detach(), this change can still allow the cloned sk's sk_user_data to be used by some other means. Freeing the reuseport_array's sk_user_data does not require a rcu grace period. Thus, the existing rcu_assign_sk_user_data_nocopy() is not used. Fixes: 5dc4c4b7d4e8 ("bpf: Introduce BPF_MAP_TYPE_REUSEPORT_SOCKARRAY") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com> Link: https://lore.kernel.org/bpf/20200709061104.4018798-1-kafai@fb.com 
It makes little sense for copying sk_user_data of reuseport_array during
sk_clone_lock().  This patch reuses the SK_USER_DATA_NOCOPY bit introduced in
commit f1ff5ce2cd5e ("net, sk_msg: Clear sk_user_data pointer on clone if tagged").
It is used to mark the sk_user_data is not supposed to be copied to its clone.

Although the cloned sk's sk_user_data will not be used/freed in
bpf_sk_reuseport_detach(), this change can still allow the cloned
sk's sk_user_data to be used by some other means.

Freeing the reuseport_array's sk_user_data does not require a rcu grace
period.  Thus, the existing rcu_assign_sk_user_data_nocopy() is not
used.

Fixes: 5dc4c4b7d4e8 ("bpf: Introduce BPF_MAP_TYPE_REUSEPORT_SOCKARRAY")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20200709061104.4018798-1-kafai@fb.com
bpf: Check correct cred for CAP_SYSLOG in bpf_dump_raw_ok() 2020-07-08T23:01:21+00:00 Kees Cook keescook@chromium.org 2020-07-02T22:45:23+00:00 63960260457a02af2a6cb35d75e6bdb17299c882 When evaluating access control over kallsyms visibility, credentials at open() time need to be used, not the "current" creds (though in BPF's case, this has likely always been the same). Plumb access to associated file->f_cred down through bpf_dump_raw_ok() and its callers now that kallsysm_show_value() has been refactored to take struct cred. Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: bpf@vger.kernel.org Cc: stable@vger.kernel.org Fixes: 7105e828c087 ("bpf: allow for correlation of maps and helpers in dump") Signed-off-by: Kees Cook <keescook@chromium.org> 
When evaluating access control over kallsyms visibility, credentials at
open() time need to be used, not the "current" creds (though in BPF's
case, this has likely always been the same). Plumb access to associated
file->f_cred down through bpf_dump_raw_ok() and its callers now that
kallsysm_show_value() has been refactored to take struct cred.

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: 7105e828c087 ("bpf: allow for correlation of maps and helpers in dump")
Signed-off-by: Kees Cook <keescook@chromium.org>
bpf: Fix an incorrect branch elimination by verifier 2020-06-30T20:21:05+00:00 Yonghong Song yhs@fb.com 2020-06-30T17:12:40+00:00 01c66c48d4f0825a202d4163800b706a1d2ec7ad Wenbo reported an issue in [1] where a checking of null pointer is evaluated as always false. In this particular case, the program type is tp_btf and the pointer to compare is a PTR_TO_BTF_ID. The current verifier considers PTR_TO_BTF_ID always reprents a non-null pointer, hence all PTR_TO_BTF_ID compares to 0 will be evaluated as always not-equal, which resulted in the branch elimination. For example, struct bpf_fentry_test_t { struct bpf_fentry_test_t *a; }; int BPF_PROG(test7, struct bpf_fentry_test_t *arg) { if (arg == 0) test7_result = 1; return 0; } int BPF_PROG(test8, struct bpf_fentry_test_t *arg) { if (arg->a == 0) test8_result = 1; return 0; } In above bpf programs, both branch arg == 0 and arg->a == 0 are removed. This may not be what developer expected. The bug is introduced by Commit cac616db39c2 ("bpf: Verifier track null pointer branch_taken with JNE and JEQ"), where PTR_TO_BTF_ID is considered to be non-null when evaluting pointer vs. scalar comparison. This may be added considering we have PTR_TO_BTF_ID_OR_NULL in the verifier as well. PTR_TO_BTF_ID_OR_NULL is added to explicitly requires a non-NULL testing in selective cases. The current generic pointer tracing framework in verifier always assigns PTR_TO_BTF_ID so users does not need to check NULL pointer at every pointer level like a->b->c->d. We may not want to assign every PTR_TO_BTF_ID as PTR_TO_BTF_ID_OR_NULL as this will require a null test before pointer dereference which may cause inconvenience for developers. But we could avoid branch elimination to preserve original code intention. This patch simply removed PTR_TO_BTD_ID from reg_type_not_null() in verifier, which prevented the above branches from being eliminated. [1]: https://lore.kernel.org/bpf/79dbb7c0-449d-83eb-5f4f-7af0cc269168@fb.com/T/ Fixes: cac616db39c2 ("bpf: Verifier track null pointer branch_taken with JNE and JEQ") Reported-by: Wenbo Zhang <ethercflow@gmail.com> Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200630171240.2523722-1-yhs@fb.com 
Wenbo reported an issue in [1] where a checking of null
pointer is evaluated as always false. In this particular
case, the program type is tp_btf and the pointer to
compare is a PTR_TO_BTF_ID.

The current verifier considers PTR_TO_BTF_ID always
reprents a non-null pointer, hence all PTR_TO_BTF_ID compares
to 0 will be evaluated as always not-equal, which resulted
in the branch elimination.

For example,
 struct bpf_fentry_test_t {
     struct bpf_fentry_test_t *a;
 };
 int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
 {
     if (arg == 0)
         test7_result = 1;
     return 0;
 }
 int BPF_PROG(test8, struct bpf_fentry_test_t *arg)
 {
     if (arg->a == 0)
         test8_result = 1;
     return 0;
 }

In above bpf programs, both branch arg == 0 and arg->a == 0
are removed. This may not be what developer expected.

The bug is introduced by Commit cac616db39c2 ("bpf: Verifier
track null pointer branch_taken with JNE and JEQ"),
where PTR_TO_BTF_ID is considered to be non-null when evaluting
pointer vs. scalar comparison. This may be added
considering we have PTR_TO_BTF_ID_OR_NULL in the verifier
as well.

PTR_TO_BTF_ID_OR_NULL is added to explicitly requires
a non-NULL testing in selective cases. The current generic
pointer tracing framework in verifier always
assigns PTR_TO_BTF_ID so users does not need to
check NULL pointer at every pointer level like a->b->c->d.

We may not want to assign every PTR_TO_BTF_ID as
PTR_TO_BTF_ID_OR_NULL as this will require a null test
before pointer dereference which may cause inconvenience
for developers. But we could avoid branch elimination
to preserve original code intention.

This patch simply removed PTR_TO_BTD_ID from reg_type_not_null()
in verifier, which prevented the above branches from being eliminated.

 [1]: https://lore.kernel.org/bpf/79dbb7c0-449d-83eb-5f4f-7af0cc269168@fb.com/T/

Fixes: cac616db39c2 ("bpf: Verifier track null pointer branch_taken with JNE and JEQ")
Reported-by: Wenbo Zhang <ethercflow@gmail.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200630171240.2523722-1-yhs@fb.com
bpf, netns: Fix use-after-free in pernet pre_exit callback 2020-06-30T17:53:42+00:00 Jakub Sitnicki jakub@cloudflare.com 2020-06-30T16:45:41+00:00 2576f87066dc08a11cb1c05f11d1eaa02148ef9e Iterating over BPF links attached to network namespace in pre_exit hook is not safe, even if there is just one. Once link gets auto-detached, that is its back-pointer to net object is set to NULL, the link can be released and freed without waiting on netns_bpf_mutex, effectively causing the list element we are operating on to be freed. This leads to use-after-free when trying to access the next element on the list, as reported by KASAN. Bug can be triggered by destroying a network namespace, while also releasing a link attached to this network namespace. | ================================================================== | BUG: KASAN: use-after-free in netns_bpf_pernet_pre_exit+0xd9/0x130 | Read of size 8 at addr ffff888119e0d778 by task kworker/u8:2/177 | | CPU: 3 PID: 177 Comm: kworker/u8:2 Not tainted 5.8.0-rc1-00197-ga0c04c9d1008-dirty #776 | Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014 | Workqueue: netns cleanup_net | Call Trace: | dump_stack+0x9e/0xe0 | print_address_description.constprop.0+0x3a/0x60 | ? netns_bpf_pernet_pre_exit+0xd9/0x130 | kasan_report.cold+0x1f/0x40 | ? netns_bpf_pernet_pre_exit+0xd9/0x130 | netns_bpf_pernet_pre_exit+0xd9/0x130 | cleanup_net+0x30b/0x5b0 | ? unregister_pernet_device+0x50/0x50 | ? rcu_read_lock_bh_held+0xb0/0xb0 | ? _raw_spin_unlock_irq+0x24/0x50 | process_one_work+0x4d1/0xa10 | ? lock_release+0x3e0/0x3e0 | ? pwq_dec_nr_in_flight+0x110/0x110 | ? rwlock_bug.part.0+0x60/0x60 | worker_thread+0x7a/0x5c0 | ? process_one_work+0xa10/0xa10 | kthread+0x1e3/0x240 | ? kthread_create_on_node+0xd0/0xd0 | ret_from_fork+0x1f/0x30 | | Allocated by task 280: | save_stack+0x1b/0x40 | __kasan_kmalloc.constprop.0+0xc2/0xd0 | netns_bpf_link_create+0xfe/0x650 | __do_sys_bpf+0x153a/0x2a50 | do_syscall_64+0x59/0x300 | entry_SYSCALL_64_after_hwframe+0x44/0xa9 | | Freed by task 198: | save_stack+0x1b/0x40 | __kasan_slab_free+0x12f/0x180 | kfree+0xed/0x350 | process_one_work+0x4d1/0xa10 | worker_thread+0x7a/0x5c0 | kthread+0x1e3/0x240 | ret_from_fork+0x1f/0x30 | | The buggy address belongs to the object at ffff888119e0d700 | which belongs to the cache kmalloc-192 of size 192 | The buggy address is located 120 bytes inside of | 192-byte region [ffff888119e0d700, ffff888119e0d7c0) | The buggy address belongs to the page: | page:ffffea0004678340 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 | flags: 0x2fffe0000000200(slab) | raw: 02fffe0000000200 ffffea00045ba8c0 0000000600000006 ffff88811a80ea80 | raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 | page dumped because: kasan: bad access detected | | Memory state around the buggy address: | ffff888119e0d600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb | ffff888119e0d680: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc | >ffff888119e0d700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb | ^ | ffff888119e0d780: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc | ffff888119e0d800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb | ================================================================== Remove the "fast-path" for releasing a link that got auto-detached by a dying network namespace to fix it. This way as long as link is on the list and netns_bpf mutex is held, we have a guarantee that link memory can be accessed. An alternative way to fix this issue would be to safely iterate over the list of links and ensure there is no access to link object after detaching it. But, at the moment, optimizing synchronization overhead on link release without a workload in mind seems like an overkill. Fixes: ab53cad90eb1 ("bpf, netns: Keep a list of attached bpf_link's") Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200630164541.1329993-1-jakub@cloudflare.com 
Iterating over BPF links attached to network namespace in pre_exit hook is
not safe, even if there is just one. Once link gets auto-detached, that is
its back-pointer to net object is set to NULL, the link can be released and
freed without waiting on netns_bpf_mutex, effectively causing the list
element we are operating on to be freed.

This leads to use-after-free when trying to access the next element on the
list, as reported by KASAN. Bug can be triggered by destroying a network
namespace, while also releasing a link attached to this network namespace.

| ==================================================================
| BUG: KASAN: use-after-free in netns_bpf_pernet_pre_exit+0xd9/0x130
| Read of size 8 at addr ffff888119e0d778 by task kworker/u8:2/177
|
| CPU: 3 PID: 177 Comm: kworker/u8:2 Not tainted 5.8.0-rc1-00197-ga0c04c9d1008-dirty #776
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014
| Workqueue: netns cleanup_net
| Call Trace:
|  dump_stack+0x9e/0xe0
|  print_address_description.constprop.0+0x3a/0x60
|  ? netns_bpf_pernet_pre_exit+0xd9/0x130
|  kasan_report.cold+0x1f/0x40
|  ? netns_bpf_pernet_pre_exit+0xd9/0x130
|  netns_bpf_pernet_pre_exit+0xd9/0x130
|  cleanup_net+0x30b/0x5b0
|  ? unregister_pernet_device+0x50/0x50
|  ? rcu_read_lock_bh_held+0xb0/0xb0
|  ? _raw_spin_unlock_irq+0x24/0x50
|  process_one_work+0x4d1/0xa10
|  ? lock_release+0x3e0/0x3e0
|  ? pwq_dec_nr_in_flight+0x110/0x110
|  ? rwlock_bug.part.0+0x60/0x60
|  worker_thread+0x7a/0x5c0
|  ? process_one_work+0xa10/0xa10
|  kthread+0x1e3/0x240
|  ? kthread_create_on_node+0xd0/0xd0
|  ret_from_fork+0x1f/0x30
|
| Allocated by task 280:
|  save_stack+0x1b/0x40
|  __kasan_kmalloc.constprop.0+0xc2/0xd0
|  netns_bpf_link_create+0xfe/0x650
|  __do_sys_bpf+0x153a/0x2a50
|  do_syscall_64+0x59/0x300
|  entry_SYSCALL_64_after_hwframe+0x44/0xa9
|
| Freed by task 198:
|  save_stack+0x1b/0x40
|  __kasan_slab_free+0x12f/0x180
|  kfree+0xed/0x350
|  process_one_work+0x4d1/0xa10
|  worker_thread+0x7a/0x5c0
|  kthread+0x1e3/0x240
|  ret_from_fork+0x1f/0x30
|
| The buggy address belongs to the object at ffff888119e0d700
|  which belongs to the cache kmalloc-192 of size 192
| The buggy address is located 120 bytes inside of
|  192-byte region [ffff888119e0d700, ffff888119e0d7c0)
| The buggy address belongs to the page:
| page:ffffea0004678340 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
| flags: 0x2fffe0000000200(slab)
| raw: 02fffe0000000200 ffffea00045ba8c0 0000000600000006 ffff88811a80ea80
| raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
| page dumped because: kasan: bad access detected
|
| Memory state around the buggy address:
|  ffff888119e0d600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
|  ffff888119e0d680: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
| >ffff888119e0d700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
|                                                                 ^
|  ffff888119e0d780: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
|  ffff888119e0d800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
| ==================================================================

Remove the "fast-path" for releasing a link that got auto-detached by a
dying network namespace to fix it. This way as long as link is on the list
and netns_bpf mutex is held, we have a guarantee that link memory can be
accessed.

An alternative way to fix this issue would be to safely iterate over the
list of links and ensure there is no access to link object after detaching
it. But, at the moment, optimizing synchronization overhead on link release
without a workload in mind seems like an overkill.

Fixes: ab53cad90eb1 ("bpf, netns: Keep a list of attached bpf_link's")
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200630164541.1329993-1-jakub@cloudflare.com
bpf: sockmap: Require attach_bpf_fd when detaching a program 2020-06-30T17:46:39+00:00 Lorenz Bauer lmb@cloudflare.com 2020-06-29T09:56:28+00:00 bb0de3131f4c60a9bf976681e0fe4d1e55c7a821 The sockmap code currently ignores the value of attach_bpf_fd when detaching a program. This is contrary to the usual behaviour of checking that attach_bpf_fd represents the currently attached program. Ensure that attach_bpf_fd is indeed the currently attached program. It turns out that all sockmap selftests already do this, which indicates that this is unlikely to cause breakage. Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200629095630.7933-5-lmb@cloudflare.com 
The sockmap code currently ignores the value of attach_bpf_fd when
detaching a program. This is contrary to the usual behaviour of
checking that attach_bpf_fd represents the currently attached
program.

Ensure that attach_bpf_fd is indeed the currently attached
program. It turns out that all sockmap selftests already do this,
which indicates that this is unlikely to cause breakage.

Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200629095630.7933-5-lmb@cloudflare.com
bpf: flow_dissector: Check value of unused flags to BPF_PROG_DETACH 2020-06-30T17:46:38+00:00 Lorenz Bauer lmb@cloudflare.com 2020-06-29T09:56:26+00:00 4ac2add65974e4efafb8d4ccd8fc5660417ea312 Using BPF_PROG_DETACH on a flow dissector program supports neither attach_flags nor attach_bpf_fd. Yet no value is enforced for them. Enforce that attach_flags are zero, and require the current program to be passed via attach_bpf_fd. This allows us to remove the check for CAP_SYS_ADMIN, since userspace can now no longer remove arbitrary flow dissector programs. Fixes: b27f7bb590ba ("flow_dissector: Move out netns_bpf prog callbacks") Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200629095630.7933-3-lmb@cloudflare.com 
Using BPF_PROG_DETACH on a flow dissector program supports neither
attach_flags nor attach_bpf_fd. Yet no value is enforced for them.

Enforce that attach_flags are zero, and require the current program
to be passed via attach_bpf_fd. This allows us to remove the check
for CAP_SYS_ADMIN, since userspace can now no longer remove
arbitrary flow dissector programs.

Fixes: b27f7bb590ba ("flow_dissector: Move out netns_bpf prog callbacks")
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200629095630.7933-3-lmb@cloudflare.com
bpf: flow_dissector: Check value of unused flags to BPF_PROG_ATTACH 2020-06-30T17:46:38+00:00 Lorenz Bauer lmb@cloudflare.com 2020-06-29T09:56:25+00:00 1b514239e85965cc4df085180a73dd91733135f7 Using BPF_PROG_ATTACH on a flow dissector program supports neither target_fd, attach_flags or replace_bpf_fd but accepts any value. Enforce that all of them are zero. This is fine for replace_bpf_fd since its presence is indicated by BPF_F_REPLACE. It's more problematic for target_fd, since zero is a valid fd. Should we want to use the flag later on we'd have to add an exception for fd 0. The alternative is to force a value like -1. This requires more changes to tests. There is also precedent for using 0, since bpf_iter uses this for target_fd as well. Fixes: b27f7bb590ba ("flow_dissector: Move out netns_bpf prog callbacks") Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200629095630.7933-2-lmb@cloudflare.com 
Using BPF_PROG_ATTACH on a flow dissector program supports neither
target_fd, attach_flags or replace_bpf_fd but accepts any value.

Enforce that all of them are zero. This is fine for replace_bpf_fd
since its presence is indicated by BPF_F_REPLACE. It's more
problematic for target_fd, since zero is a valid fd. Should we
want to use the flag later on we'd have to add an exception for
fd 0. The alternative is to force a value like -1. This requires
more changes to tests. There is also precedent for using 0,
since bpf_iter uses this for target_fd as well.

Fixes: b27f7bb590ba ("flow_dissector: Move out netns_bpf prog callbacks")
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200629095630.7933-2-lmb@cloudflare.com