Applications with many concurrent connections, high variance
in receive queue length and tight memory bounds cannot
allocate worst-case buffer size to drain sockets. Knowing
the size of receive queue length, applications can optimize
how they allocate buffers to read from the socket.
The number of bytes pending on the socket is directly
available through ioctl(FIONREAD/SIOCINQ) and can be
approximated using getsockopt(MEMINFO) (rmem_alloc includes
skb overheads in addition to application data). But, both of
these options add an extra syscall per recvmsg. Moreover,
ioctl(FIONREAD/SIOCINQ) takes the socket lock.
Add the TCP_INQ socket option to TCP. When this socket
option is set, recvmsg() relays the number of bytes available
on the socket for reading to the application via the
TCP_CM_INQ control message.
Calculate the number of bytes after releasing the socket lock
to include the processed backlog, if any. To avoid an extra
branch in the hot path of recvmsg() for this new control
message, move all cmsg processing inside an existing branch for
processing receive timestamps. Since the socket lock is not held
when calculating the size of receive queue, TCP_INQ is a hint.
For example, it can overestimate the queue size by one byte,
if FIN is received.
With this method, applications can start reading from the socket
using a small buffer, and then use larger buffers based on the
remaining data when needed.
V3 change-log:
As suggested by David Miller, added loads with barrier
to check whether we have multiple threads calling recvmsg
in parallel. When that happens we lock the socket to
calculate inq.
V4 change-log:
Removed inline from a static function.
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Suggested-by: David Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
The intention is to get notified of process failures as soon
as possible, before a possible core dumping (which could be very long)
(e.g. in some process-manager). Coredump and exit process events
are perfect for such use cases (see 2b5faa4c55 "connector: Added
coredumping event to the process connector").
The problem is that for now the process-manager cannot know the parent
of a dying process using connectors. This could be useful if the
process-manager should monitor for failures only children of certain
parents, so we could filter the coredump and exit events by parent
process and/or thread ID.
Add parent pid and tgid to coredump and exit process connectors event
data.
Signed-off-by: Stefan Strogin <sstrogin@cisco.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
When adding tcp mmap() implementation, I forgot that socket lock
had to be taken before current->mm->mmap_sem. syzbot eventually caught
the bug.
Since we can not lock the socket in tcp mmap() handler we have to
split the operation in two phases.
1) mmap() on a tcp socket simply reserves VMA space, and nothing else.
This operation does not involve any TCP locking.
2) getsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) implements
the transfert of pages from skbs to one VMA.
This operation only uses down_read(¤t->mm->mmap_sem) after
holding TCP lock, thus solving the lockdep issue.
This new implementation was suggested by Andy Lutomirski with great details.
Benefits are :
- Better scalability, in case multiple threads reuse VMAS
(without mmap()/munmap() calls) since mmap_sem wont be write locked.
- Better error recovery.
The previous mmap() model had to provide the expected size of the
mapping. If for some reason one part could not be mapped (partial MSS),
the whole operation had to be aborted.
With the tcp_zerocopy_receive struct, kernel can report how
many bytes were successfuly mapped, and how many bytes should
be read to skip the problematic sequence.
- No more memory allocation to hold an array of page pointers.
16 MB mappings needed 32 KB for this array, potentially using vmalloc() :/
- skbs are freed while mmap_sem has been released
Following patch makes the change in tcp_mmap tool to demonstrate
one possible use of mmap() and setsockopt(... TCP_ZEROCOPY_RECEIVE ...)
Note that memcg might require additional changes.
Fixes: 93ab6cc691 ("tcp: implement mmap() for zero copy receive")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Suggested-by: Andy Lutomirski <luto@kernel.org>
Cc: linux-mm@kvack.org
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull timer fixes from Thomas Gleixner:
"Two fixes from the timer departement:
- Fix a long standing issue in the NOHZ tick code which causes RB
tree corruption, delayed timers and other malfunctions. The cause
for this is code which modifies the expiry time of an enqueued
hrtimer.
- Revert the CLOCK_MONOTONIC/CLOCK_BOOTTIME unification due to
regression reports. Seems userspace _is_ relying on the documented
behaviour despite our hope that it wont"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Revert: Unify CLOCK_MONOTONIC and CLOCK_BOOTTIME
tick/sched: Do not mess with an enqueued hrtimer
Pull KVM fixes from Radim Krčmář:
"ARM:
- PSCI selection API, a leftover from 4.16 (for stable)
- Kick vcpu on active interrupt affinity change
- Plug a VMID allocation race on oversubscribed systems
- Silence debug messages
- Update Christoffer's email address (linaro -> arm)
x86:
- Expose userspace-relevant bits of a newly added feature
- Fix TLB flushing on VMX with VPID, but without EPT"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
x86/headers/UAPI: Move DISABLE_EXITS KVM capability bits to the UAPI
kvm: apic: Flush TLB after APIC mode/address change if VPIDs are in use
arm/arm64: KVM: Add PSCI version selection API
KVM: arm/arm64: vgic: Kick new VCPU on interrupt migration
arm64: KVM: Demote SVE and LORegion warnings to debug only
MAINTAINERS: Update e-mail address for Christoffer Dall
KVM: arm/arm64: Close VMID generation race
Pull staging fixes from Greg KH:
"Here are two staging driver fixups for 4.17-rc3.
The first is the remaining stragglers of the irda code removal that
you pointed out during the merge window. The second is a fix for the
wilc1000 driver due to a patch that got merged in 4.17-rc1.
Both of these have been in linux-next for a while with no reported
issues"
* tag 'staging-4.17-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
staging: wilc1000: fix NULL pointer exception in host_int_parse_assoc_resp_info()
staging: irda: remove remaining remants of irda code removal
After the introduction of a 128-bit node identity it may be difficult
for a user to correlate between this identity and the generated node
hash address.
We now try to make this easier by introducing a new ioctl() call for
fetching a node identity by using the hash value as key. This will
be particularly useful when we extend some of the commands in the
'tipc' tool, but we also expect regular user applications to need
this feature.
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Daniel Borkmann says:
====================
pull-request: bpf-next 2018-04-27
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) Add extensive BPF helper description into include/uapi/linux/bpf.h
and a new script bpf_helpers_doc.py which allows for generating a
man page out of it. Thus, every helper in BPF now comes with proper
function signature, detailed description and return code explanation,
from Quentin.
2) Migrate the BPF collect metadata tunnel tests from BPF samples over
to the BPF selftests and further extend them with v6 vxlan, geneve
and ipip tests, simplify the ipip tests, improve documentation and
convert to bpf_ntoh*() / bpf_hton*() api, from William.
3) Currently, helpers that expect ARG_PTR_TO_MAP_{KEY,VALUE} can only
access stack and packet memory. Extend this to allow such helpers
to also use map values, which enabled use cases where value from
a first lookup can be directly used as a key for a second lookup,
from Paul.
4) Add a new helper bpf_skb_get_xfrm_state() for tc BPF programs in
order to retrieve XFRM state information containing SPI, peer
address and reqid values, from Eyal.
5) Various optimizations in nfp driver's BPF JIT in order to turn ADD
and SUB instructions with negative immediate into the opposite
operation with a positive immediate such that nfp can better fit
small immediates into instructions. Savings in instruction count
up to 4% have been observed, from Jakub.
6) Add the BPF prog's gpl_compatible flag to struct bpf_prog_info
and add support for dumping this through bpftool, from Jiri.
7) Move the BPF sockmap samples over into BPF selftests instead since
sockmap was rather a series of tests than sample anyway and this way
this can be run from automated bots, from John.
8) Follow-up fix for bpf_adjust_tail() helper in order to make it work
with generic XDP, from Nikita.
9) Some follow-up cleanups to BTF, namely, removing unused defines from
BTF uapi header and renaming 'name' struct btf_* members into name_off
to make it more clear they are offsets into string section, from Martin.
10) Remove test_sock_addr from TEST_GEN_PROGS in BPF selftests since
not run directly but invoked from test_sock_addr.sh, from Yonghong.
11) Remove redundant ret assignment in sample BPF loader, from Wang.
12) Add couple of missing files to BPF selftest's gitignore, from Anders.
There are two trivial merge conflicts while pulling:
1) Remove samples/sockmap/Makefile since all sockmap tests have been
moved to selftests.
2) Add both hunks from tools/testing/selftests/bpf/.gitignore to the
file since git should ignore all of them.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Add documentation for eBPF helper functions to bpf.h user header file.
This documentation can be parsed with the Python script provided in
another commit of the patch series, in order to provide a RST document
that can later be converted into a man page.
The objective is to make the documentation easily understandable and
accessible to all eBPF developers, including beginners.
This patch contains descriptions for the following helper functions:
Helper from Nikita:
- bpf_xdp_adjust_tail()
Helper from Eyal:
- bpf_skb_get_xfrm_state()
v4:
- New patch (helpers did not exist yet for previous versions).
Cc: Nikita V. Shirokov <tehnerd@tehnerd.com>
Cc: Eyal Birger <eyal.birger@gmail.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add documentation for eBPF helper functions to bpf.h user header file.
This documentation can be parsed with the Python script provided in
another commit of the patch series, in order to provide a RST document
that can later be converted into a man page.
The objective is to make the documentation easily understandable and
accessible to all eBPF developers, including beginners.
This patch contains descriptions for the following helper functions, all
written by John:
- bpf_redirect_map()
- bpf_sk_redirect_map()
- bpf_sock_map_update()
- bpf_msg_redirect_map()
- bpf_msg_apply_bytes()
- bpf_msg_cork_bytes()
- bpf_msg_pull_data()
v4:
- bpf_redirect_map(): Fix typos: "XDP_ABORT" changed to "XDP_ABORTED",
"his" to "this". Also add a paragraph on performance improvement over
bpf_redirect() helper.
v3:
- bpf_sk_redirect_map(): Improve description of BPF_F_INGRESS flag.
- bpf_msg_redirect_map(): Improve description of BPF_F_INGRESS flag.
- bpf_redirect_map(): Fix note on CPU redirection, not fully implemented
for generic XDP but supported on native XDP.
- bpf_msg_pull_data(): Clarify comment about invalidated verifier
checks.
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add documentation for eBPF helper functions to bpf.h user header file.
This documentation can be parsed with the Python script provided in
another commit of the patch series, in order to provide a RST document
that can later be converted into a man page.
The objective is to make the documentation easily understandable and
accessible to all eBPF developers, including beginners.
This patch contains descriptions for the following helper functions:
Helpers from Lawrence:
- bpf_setsockopt()
- bpf_getsockopt()
- bpf_sock_ops_cb_flags_set()
Helpers from Yonghong:
- bpf_perf_event_read_value()
- bpf_perf_prog_read_value()
Helper from Josef:
- bpf_override_return()
Helper from Andrey:
- bpf_bind()
v4:
- bpf_perf_event_read_value(): State that this helper should be
preferred over bpf_perf_event_read().
v3:
- bpf_perf_event_read_value(): Fix time of selection for perf event type
in description. Remove occurences of "cores" to avoid confusion with
"CPU".
- bpf_bind(): Remove last paragraph of description, which was off topic.
Cc: Lawrence Brakmo <brakmo@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Yonghong Song <yhs@fb.com>
[for bpf_perf_event_read_value(), bpf_perf_prog_read_value()]
Acked-by: Andrey Ignatov <rdna@fb.com>
[for bpf_bind()]
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add documentation for eBPF helper functions to bpf.h user header file.
This documentation can be parsed with the Python script provided in
another commit of the patch series, in order to provide a RST document
that can later be converted into a man page.
The objective is to make the documentation easily understandable and
accessible to all eBPF developers, including beginners.
This patch contains descriptions for the following helper functions:
Helper from Kaixu:
- bpf_perf_event_read()
Helpers from Martin:
- bpf_skb_under_cgroup()
- bpf_xdp_adjust_head()
Helpers from Sargun:
- bpf_probe_write_user()
- bpf_current_task_under_cgroup()
Helper from Thomas:
- bpf_skb_change_head()
Helper from Gianluca:
- bpf_probe_read_str()
Helpers from Chenbo:
- bpf_get_socket_cookie()
- bpf_get_socket_uid()
v4:
- bpf_perf_event_read(): State that bpf_perf_event_read_value() should
be preferred over this helper.
- bpf_skb_change_head(): Clarify comment about invalidated verifier
checks.
- bpf_xdp_adjust_head(): Clarify comment about invalidated verifier
checks.
- bpf_probe_write_user(): Add that dst must be a valid user space
address.
- bpf_get_socket_cookie(): Improve description by making clearer that
the cockie belongs to the socket, and state that it remains stable for
the life of the socket.
v3:
- bpf_perf_event_read(): Fix time of selection for perf event type in
description. Remove occurences of "cores" to avoid confusion with
"CPU".
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Sargun Dhillon <sargun@sargun.me>
Cc: Thomas Graf <tgraf@suug.ch>
Cc: Gianluca Borello <g.borello@gmail.com>
Cc: Chenbo Feng <fengc@google.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
[for bpf_skb_under_cgroup(), bpf_xdp_adjust_head()]
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add documentation for eBPF helper functions to bpf.h user header file.
This documentation can be parsed with the Python script provided in
another commit of the patch series, in order to provide a RST document
that can later be converted into a man page.
The objective is to make the documentation easily understandable and
accessible to all eBPF developers, including beginners.
This patch contains descriptions for the following helper functions, all
written by Daniel:
- bpf_get_hash_recalc()
- bpf_skb_change_tail()
- bpf_skb_pull_data()
- bpf_csum_update()
- bpf_set_hash_invalid()
- bpf_get_numa_node_id()
- bpf_set_hash()
- bpf_skb_adjust_room()
- bpf_xdp_adjust_meta()
v4:
- bpf_skb_change_tail(): Clarify comment about invalidated verifier
checks.
- bpf_skb_pull_data(): Clarify the motivation for using this helper or
bpf_skb_load_bytes(), on non-linear buffers. Fix RST formatting for
*skb*. Clarify comment about invalidated verifier checks.
- bpf_csum_update(): Fix description of checksum (entire packet, not IP
checksum). Fix a typo: "header" instead of "helper".
- bpf_set_hash_invalid(): Mention bpf_get_hash_recalc().
- bpf_get_numa_node_id(): State that the helper is not restricted to
programs attached to sockets.
- bpf_skb_adjust_room(): Clarify comment about invalidated verifier
checks.
- bpf_xdp_adjust_meta(): Clarify comment about invalidated verifier
checks.
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add documentation for eBPF helper functions to bpf.h user header file.
This documentation can be parsed with the Python script provided in
another commit of the patch series, in order to provide a RST document
that can later be converted into a man page.
The objective is to make the documentation easily understandable and
accessible to all eBPF developers, including beginners.
This patch contains descriptions for the following helper functions, all
written by Daniel:
- bpf_get_prandom_u32()
- bpf_get_smp_processor_id()
- bpf_get_cgroup_classid()
- bpf_get_route_realm()
- bpf_skb_load_bytes()
- bpf_csum_diff()
- bpf_skb_get_tunnel_opt()
- bpf_skb_set_tunnel_opt()
- bpf_skb_change_proto()
- bpf_skb_change_type()
v4:
- bpf_get_prandom_u32(): Warn that the prng is not cryptographically
secure.
- bpf_get_smp_processor_id(): Fix a typo (case).
- bpf_get_cgroup_classid(): Clarify description. Add notes on the helper
being limited to cgroup v1, and to egress path.
- bpf_get_route_realm(): Add comparison with bpf_get_cgroup_classid().
Add a note about usage with TC and advantage of clsact. Fix a typo in
return value ("sdb" instead of "skb").
- bpf_skb_load_bytes(): Make explicit loading large data loads it to the
eBPF stack.
- bpf_csum_diff(): Add a note on seed that can be cascaded. Link to
bpf_l3|l4_csum_replace().
- bpf_skb_get_tunnel_opt(): Add a note about usage with "collect
metadata" mode, and example of this with Geneve.
- bpf_skb_set_tunnel_opt(): Add a link to bpf_skb_get_tunnel_opt()
description.
- bpf_skb_change_proto(): Mention that the main use case is NAT64.
Clarify comment about invalidated verifier checks.
v3:
- bpf_get_prandom_u32(): Fix helper name :(. Add description, including
a note on the internal random state.
- bpf_get_smp_processor_id(): Add description, including a note on the
processor id remaining stable during program run.
- bpf_get_cgroup_classid(): State that CONFIG_CGROUP_NET_CLASSID is
required to use the helper. Add a reference to related documentation.
State that placing a task in net_cls controller disables cgroup-bpf.
- bpf_get_route_realm(): State that CONFIG_CGROUP_NET_CLASSID is
required to use this helper.
- bpf_skb_load_bytes(): Fix comment on current use cases for the helper.
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add documentation for eBPF helper functions to bpf.h user header file.
This documentation can be parsed with the Python script provided in
another commit of the patch series, in order to provide a RST document
that can later be converted into a man page.
The objective is to make the documentation easily understandable and
accessible to all eBPF developers, including beginners.
This patch contains descriptions for the following helper functions, all
written by Alexei:
- bpf_get_current_pid_tgid()
- bpf_get_current_uid_gid()
- bpf_get_current_comm()
- bpf_skb_vlan_push()
- bpf_skb_vlan_pop()
- bpf_skb_get_tunnel_key()
- bpf_skb_set_tunnel_key()
- bpf_redirect()
- bpf_perf_event_output()
- bpf_get_stackid()
- bpf_get_current_task()
v4:
- bpf_redirect(): Fix typo: "XDP_ABORT" changed to "XDP_ABORTED". Add
note on bpf_redirect_map() providing better performance. Replace "Save
for" with "Except for".
- bpf_skb_vlan_push(): Clarify comment about invalidated verifier
checks.
- bpf_skb_vlan_pop(): Clarify comment about invalidated verifier
checks.
- bpf_skb_get_tunnel_key(): Add notes on tunnel_id, "collect metadata"
mode, and example tunneling protocols with which it can be used.
- bpf_skb_set_tunnel_key(): Add a reference to the description of
bpf_skb_get_tunnel_key().
- bpf_perf_event_output(): Specify that, and for what purpose, the
helper can be used with programs attached to TC and XDP.
v3:
- bpf_skb_get_tunnel_key(): Change and improve description and example.
- bpf_redirect(): Improve description of BPF_F_INGRESS flag.
- bpf_perf_event_output(): Fix first sentence of description. Delete
wrong statement on context being evaluated as a struct pt_reg. Remove
the long yet incomplete example.
- bpf_get_stackid(): Add a note about PERF_MAX_STACK_DEPTH being
configurable.
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add documentation for eBPF helper functions to bpf.h user header file.
This documentation can be parsed with the Python script provided in
another commit of the patch series, in order to provide a RST document
that can later be converted into a man page.
The objective is to make the documentation easily understandable and
accessible to all eBPF developers, including beginners.
This patch contains descriptions for the following helper functions, all
written by Alexei:
- bpf_map_lookup_elem()
- bpf_map_update_elem()
- bpf_map_delete_elem()
- bpf_probe_read()
- bpf_ktime_get_ns()
- bpf_trace_printk()
- bpf_skb_store_bytes()
- bpf_l3_csum_replace()
- bpf_l4_csum_replace()
- bpf_tail_call()
- bpf_clone_redirect()
v4:
- bpf_map_lookup_elem(): Add "const" qualifier for key.
- bpf_map_update_elem(): Add "const" qualifier for key and value.
- bpf_map_lookup_elem(): Add "const" qualifier for key.
- bpf_skb_store_bytes(): Clarify comment about invalidated verifier
checks.
- bpf_l3_csum_replace(): Mention L3 instead of just IP, and add a note
about bpf_csum_diff().
- bpf_l4_csum_replace(): Mention L4 instead of just TCP/UDP, and add a
note about bpf_csum_diff().
- bpf_tail_call(): Bring minor edits to description.
- bpf_clone_redirect(): Add a note about the relation with
bpf_redirect(). Also clarify comment about invalidated verifier
checks.
v3:
- bpf_map_lookup_elem(): Fix description of restrictions for flags
related to the existence of the entry.
- bpf_trace_printk(): State that trace_pipe can be configured. Fix
return value in case an unknown format specifier is met. Add a note on
kernel log notice when the helper is used. Edit example.
- bpf_tail_call(): Improve comment on stack inheritance.
- bpf_clone_redirect(): Improve description of BPF_F_INGRESS flag.
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Remove previous "overview" of eBPF helpers from user bpf.h header.
Replace it by a comment explaining how to process the new documentation
(to come in following patches) with a Python script to produce RST, then
man page documentation.
Also add the aforementioned Python script under scripts/. It is used to
process include/uapi/linux/bpf.h and to extract helper descriptions, to
turn it into a RST document that can further be processed with rst2man
to produce a man page. The script takes one "--filename <path/to/file>"
option. If the script is launched from scripts/ in the kernel root
directory, it should be able to find the location of the header to
parse, and "--filename <path/to/file>" is then optional. If it cannot
find the file, then the option becomes mandatory. RST-formatted
documentation is printed to standard output.
Typical workflow for producing the final man page would be:
$ ./scripts/bpf_helpers_doc.py \
--filename include/uapi/linux/bpf.h > /tmp/bpf-helpers.rst
$ rst2man /tmp/bpf-helpers.rst > /tmp/bpf-helpers.7
$ man /tmp/bpf-helpers.7
Note that the tool kernel-doc cannot be used to document eBPF helpers,
whose signatures are not available directly in the header files
(pre-processor directives are used to produce them at the beginning of
the compilation process).
v4:
- Also remove overviews for newly added bpf_xdp_adjust_tail() and
bpf_skb_get_xfrm_state().
- Remove vague statement about what helpers are restricted to GPL
programs in "LICENSE" section for man page footer.
- Replace license boilerplate with SPDX tag for Python script.
v3:
- Change license for man page.
- Remove "for safety reasons" from man page header text.
- Change "packets metadata" to "packets" in man page header text.
- Move and fix comment on helpers introducing no overhead.
- Remove "NOTES" section from man page footer.
- Add "LICENSE" section to man page footer.
- Edit description of file include/uapi/linux/bpf.h in man page footer.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Adding gpl_compatible flag to struct bpf_prog_info
so it can be dumped via bpf_prog_get_info_by_fd and
displayed via bpftool progs dump.
Alexei noticed 4-byte hole in struct bpf_prog_info,
so we put the u32 flags field in there, and we can
keep adding bit fields in there without breaking
user space.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Support generic segmentation offload for udp datagrams. Callers can
concatenate and send at once the payload of multiple datagrams with
the same destination.
To set segment size, the caller sets socket option UDP_SEGMENT to the
length of each discrete payload. This value must be smaller than or
equal to the relevant MTU.
A follow-up patch adds cmsg UDP_SEGMENT to specify segment size on a
per send call basis.
Total byte length may then exceed MTU. If not an exact multiple of
segment size, the last segment will be shorter.
The implementation adds a gso_size field to the udp socket, ip(v6)
cmsg cookie and inet_cork structure to be able to set the value at
setsockopt or cmsg time and to work with both lockless and corked
paths.
Initial benchmark numbers show UDP GSO about as expensive as TCP GSO.
tcp tso
3197 MB/s 54232 msg/s 54232 calls/s
6,457,754,262 cycles
tcp gso
1765 MB/s 29939 msg/s 29939 calls/s
11,203,021,806 cycles
tcp without tso/gso *
739 MB/s 12548 msg/s 12548 calls/s
11,205,483,630 cycles
udp
876 MB/s 14873 msg/s 624666 calls/s
11,205,777,429 cycles
udp gso
2139 MB/s 36282 msg/s 36282 calls/s
11,204,374,561 cycles
[*] after reverting commit 0a6b2a1dc2
("tcp: switch to GSO being always on")
Measured total system cycles ('-a') for one core while pinning both
the network receive path and benchmark process to that core:
perf stat -a -C 12 -e cycles \
./udpgso_bench_tx -C 12 -4 -D "$DST" -l 4
Note the reduction in calls/s with GSO. Bytes per syscall drops
increases from 1470 to 61818.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Revert commits
92af4dcb4e ("tracing: Unify the "boot" and "mono" tracing clocks")
127bfa5f43 ("hrtimer: Unify MONOTONIC and BOOTTIME clock behavior")
7250a4047a ("posix-timers: Unify MONOTONIC and BOOTTIME clock behavior")
d6c7270e91 ("timekeeping: Remove boot time specific code")
f2d6fdbfd2 ("Input: Evdev - unify MONOTONIC and BOOTTIME clock behavior")
d6ed449afd ("timekeeping: Make the MONOTONIC clock behave like the BOOTTIME clock")
72199320d4 ("timekeeping: Add the new CLOCK_MONOTONIC_ACTIVE clock")
As stated in the pull request for the unification of CLOCK_MONOTONIC and
CLOCK_BOOTTIME, it was clear that we might have to revert the change.
As reported by several folks systemd and other applications rely on the
documented behaviour of CLOCK_MONOTONIC on Linux and break with the above
changes. After resume daemons time out and other timeout related issues are
observed. Rafael compiled this list:
* systemd kills daemons on resume, after >WatchdogSec seconds
of suspending (Genki Sky). [Verified that that's because systemd uses
CLOCK_MONOTONIC and expects it to not include the suspend time.]
* systemd-journald misbehaves after resume:
systemd-journald[7266]: File /var/log/journal/016627c3c4784cd4812d4b7e96a34226/system.journal
corrupted or uncleanly shut down, renaming and replacing.
(Mike Galbraith).
* NetworkManager reports "networking disabled" and networking is broken
after resume 50% of the time (Pavel). [May be because of systemd.]
* MATE desktop dims the display and starts the screensaver right after
system resume (Pavel).
* Full system hang during resume (me). [May be due to systemd or NM or both.]
That happens on debian and open suse systems.
It's sad, that these problems were neither catched in -next nor by those
folks who expressed interest in this change.
Reported-by: Rafael J. Wysocki <rjw@rjwysocki.net>
Reported-by: Genki Sky <sky@genki.is>,
Reported-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kevin Easton <kevin@guarana.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
This commit introduces a helper which allows fetching xfrm state
parameters by eBPF programs attached to TC.
Prototype:
bpf_skb_get_xfrm_state(skb, index, xfrm_state, size, flags)
skb: pointer to skb
index: the index in the skb xfrm_state secpath array
xfrm_state: pointer to 'struct bpf_xfrm_state'
size: size of 'struct bpf_xfrm_state'
flags: reserved for future extensions
The helper returns 0 on success. Non zero if no xfrm state at the index
is found - or non exists at all.
struct bpf_xfrm_state currently includes the SPI, peer IPv4/IPv6
address and the reqid; it can be further extended by adding elements to
its end - indicating the populated fields by the 'size' argument -
keeping backwards compatibility.
Typical usage:
struct bpf_xfrm_state x = {};
bpf_skb_get_xfrm_state(skb, 0, &x, sizeof(x), 0);
...
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Jason Wang points out that it's very hard for users to build an array of
stat names. The naive thing is to use VIRTIO_BALLOON_S_NR but that
breaks if we add more stats - as done e.g. recently by commit 6c64fe7f2
("virtio_balloon: export hugetlb page allocation counts").
Let's add an array of reasonably readable names.
Fixes: 6c64fe7f2 ("virtio_balloon: export hugetlb page allocation counts")
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Jonathan Helman <jonathan.helman@oracle.com>
This patch cleans up btf.h in uapi:
1) Rename "name" to "name_off" to better reflect it is an offset to the
string section instead of a char array.
2) Remove unused value BTF_FLAGS_COMPR and BTF_MAGIC_SWAP
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Pull perf fixes from Thomas Gleixner:
"A larger set of updates for perf.
Kernel:
- Handle the SBOX uncore monitoring correctly on Broadwell CPUs which
do not have SBOX.
- Store context switch out type in PERF_RECORD_SWITCH[_CPU_WIDE]. The
percentage of preempting and non-preempting context switches help
understanding the nature of workloads (CPU or IO bound) that are
running on a machine. This adds the kernel facility and userspace
changes needed to show this information in 'perf script' and 'perf
report -D' (Alexey Budankov)
- Remove a WARN_ON() in the trace/kprobes code which is pointless
because the return error code is already telling the caller what's
wrong.
- Revert a fugly workaround for clang BPF targets.
- Fix sample_max_stack maximum check and do not proceed when an error
has been detect, return them to avoid misidentifying errors (Jiri
Olsa)
- Add SPDX idenitifiers and get rid of GPL boilderplate.
Tools:
- Synchronize kernel ABI headers, v4.17-rc1 (Ingo Molnar)
- Support MAP_FIXED_NOREPLACE, noticed when updating the
tools/include/ copies (Arnaldo Carvalho de Melo)
- Add '\n' at the end of parse-options error messages (Ravi Bangoria)
- Add s390 support for detailed/verbose PMU event description (Thomas
Richter)
- perf annotate fixes and improvements:
* Allow showing offsets in more than just jump targets, use the
new 'O' hotkey in the TUI, config ~/.perfconfig
annotate.offset_level for it and for --stdio2 (Arnaldo Carvalho
de Melo)
* Use the resolved variable names from objdump disassembled lines
to make them more compact, just like was already done for some
instructions, like "mov", this eventually will be done more
generally, but lets now add some more to the existing mechanism
(Arnaldo Carvalho de Melo)
- perf record fixes:
* Change warning for missing topology sysfs entry to debug, as not
all architectures have those files, s390 being one of those
(Thomas Richter)
* Remove old error messages about things that unlikely to be the
root cause in modern systems (Andi Kleen)
- perf sched fixes:
* Fix -g/--call-graph documentation (Takuya Yamamoto)
- perf stat:
* Enable 1ms interval for printing event counters values in
(Alexey Budankov)
- perf test fixes:
* Run dwarf unwind on arm32 (Kim Phillips)
* Remove unused ptrace.h include from LLVM test, sidesteping older
clang's lack of support for some asm constructs (Arnaldo
Carvalho de Melo)
* Fixup BPF test using epoll_pwait syscall function probe, to cope
with the syscall routines renames performed in this development
cycle (Arnaldo Carvalho de Melo)
- perf version fixes:
* Do not print info about HAVE_LIBAUDIT_SUPPORT in 'perf version
--build-options' when HAVE_SYSCALL_TABLE_SUPPORT is true, as
libaudit won't be used in that case, print info about
syscall_table support instead (Jin Yao)
- Build system fixes:
* Use HAVE_..._SUPPORT used consistently (Jin Yao)
* Restore READ_ONCE() C++ compatibility in tools/include (Mark
Rutland)
* Give hints about package names needed to build jvmti (Arnaldo
Carvalho de Melo)"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits)
perf/x86/intel/uncore: Fix SBOX support for Broadwell CPUs
perf/x86/intel/uncore: Revert "Remove SBOX support for Broadwell server"
coresight: Move to SPDX identifier
perf test BPF: Fixup BPF test using epoll_pwait syscall function probe
perf tests mmap: Show which tracepoint is failing
perf tools: Add '\n' at the end of parse-options error messages
perf record: Remove suggestion to enable APIC
perf record: Remove misleading error suggestion
perf hists browser: Clarify top/report browser help
perf mem: Allow all record/report options
perf trace: Support MAP_FIXED_NOREPLACE
perf: Remove superfluous allocation error check
perf: Fix sample_max_stack maximum check
perf: Return proper values for user stack errors
perf list: Add s390 support for detailed/verbose PMU event description
perf script: Extend misc field decoding with switch out event type
perf report: Extend raw dump (-D) out with switch out event type
perf/core: Store context switch out type in PERF_RECORD_SWITCH[_CPU_WIDE]
tools/headers: Synchronize kernel ABI headers, v4.17-rc1
trace_kprobe: Remove warning message "Could not insert probe at..."
...
Pull /dev/random fixes from Ted Ts'o:
"Fix some bugs in the /dev/random driver which causes getrandom(2) to
unblock earlier than designed.
Thanks to Jann Horn from Google's Project Zero for pointing this out
to me"
* tag 'random_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
random: add new ioctl RNDRESEEDCRNG
random: crng_reseed() should lock the crng instance that it is modifying
random: set up the NUMA crng instances after the CRNG is fully initialized
random: use a different mixing algorithm for add_device_randomness()
random: fix crng_ready() test
Daniel Borkmann says:
====================
pull-request: bpf-next 2018-04-21
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) Initial work on BPF Type Format (BTF) is added, which is a meta
data format which describes the data types of BPF programs / maps.
BTF has its roots from CTF (Compact C-Type format) with a number
of changes to it. First use case is to provide a generic pretty
print capability for BPF maps inspection, later work will also
add BTF to bpftool. pahole support to convert dwarf to BTF will
be upstreamed as well (https://github.com/iamkafai/pahole/tree/btf),
from Martin.
2) Add a new xdp_bpf_adjust_tail() BPF helper for XDP that allows
for changing the data_end pointer. Only shrinking is currently
supported which helps for crafting ICMP control messages. Minor
changes in drivers have been added where needed so they recalc
the packet's length also when data_end was adjusted, from Nikita.
3) Improve bpftool to make it easier to feed hex bytes via cmdline
for map operations, from Quentin.
4) Add support for various missing BPF prog types and attach types
that have been added to kernel recently but neither to bpftool
nor libbpf yet. Doc and bash completion updates have been added
as well for bpftool, from Andrey.
5) Proper fix for avoiding to leak info stored in frame data on page
reuse for the two bpf_xdp_adjust_{head,meta} helpers by disallowing
to move the pointers into struct xdp_frame area, from Jesper.
6) Follow-up compile fix from BTF in order to include stdbool.h in
libbpf, from Björn.
7) Few fixes in BPF sample code, that is, a typo on the netdevice
in a comment and fixup proper dump of XDP action code in the
tracepoint exception, from Wang and Jesper.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
In previous commit, we changed the default emulated MTU for UDP bearers
to 14k.
This commit adds the functionality to set/change the default value
by configuring new MTU for UDP media. UDP bearer(s) have to be disabled
and enabled back for the new MTU to take effect.
Acked-by: Ying Xue <ying.xue@windriver.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: GhantaKrishnamurthy MohanKrishna <mohan.krishna.ghanta.krishnamurthy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, all bearers are configured with MTU value same as the
underlying L2 device. However, in case of bearers with media type
UDP, higher throughput is possible with a fixed and higher emulated
MTU value than adapting to the underlying L2 MTU.
In this commit, we introduce a parameter mtu in struct tipc_media
and a default value is set for UDP. A default value of 14k
was determined by experimentation and found to have a higher throughput
than 16k. MTU for UDP bearers are assigned the above set value of
media MTU.
Acked-by: Ying Xue <ying.xue@windriver.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: GhantaKrishnamurthy MohanKrishna <mohan.krishna.ghanta.krishnamurthy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds pretty print support to the basic arraymap.
Support for other bpf maps can be added later.
This patch adds new attrs to the BPF_MAP_CREATE command to allow
specifying the btf_fd, btf_key_id and btf_value_id. The
BPF_MAP_CREATE can then associate the btf to the map if
the creating map supports BTF.
A BTF supported map needs to implement two new map ops,
map_seq_show_elem() and map_check_btf(). This patch has
implemented these new map ops for the basic arraymap.
It also adds file_operations, bpffs_map_fops, to the pinned
map such that the pinned map can be opened and read.
After that, the user has an intuitive way to do
"cat bpffs/pathto/a-pinned-map" instead of getting
an error.
bpffs_map_fops should not be extended further to support
other operations. Other operations (e.g. write/key-lookup...)
should be realized by the userspace tools (e.g. bpftool) through
the BPF_OBJ_GET_INFO_BY_FD, map's lookup/update interface...etc.
Follow up patches will allow the userspace to obtain
the BTF from a map-fd.
Here is a sample output when reading a pinned arraymap
with the following map's value:
struct map_value {
int count_a;
int count_b;
};
cat /sys/fs/bpf/pinned_array_map:
0: {1,2}
1: {3,4}
2: {5,6}
...
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch adds a BPF_BTF_LOAD command which
1) loads and verifies the BTF (implemented in earlier patches)
2) returns a BTF fd to userspace. In the next patch, the
BTF fd can be specified during BPF_MAP_CREATE.
It currently limits to CAP_SYS_ADMIN.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This patch introduces BPF type Format (BTF).
BTF (BPF Type Format) is the meta data format which describes
the data types of BPF program/map. Hence, it basically focus
on the C programming language which the modern BPF is primary
using. The first use case is to provide a generic pretty print
capability for a BPF map.
BTF has its root from CTF (Compact C-Type format). To simplify
the handling of BTF data, BTF removes the differences between
small and big type/struct-member. Hence, BTF consistently uses u32
instead of supporting both "one u16" and "two u32 (+padding)" in
describing type and struct-member.
It also raises the number of types (and functions) limit
from 0x7fff to 0x7fffffff.
Due to the above changes, the format is not compatible to CTF.
Hence, BTF starts with a new BTF_MAGIC and version number.
This patch does the first verification pass to the BTF. The first
pass checks:
1. meta-data size (e.g. It does not go beyond the total btf's size)
2. name_offset is valid
3. Each BTF_KIND (e.g. int, enum, struct....) does its
own check of its meta-data.
Some other checks, like checking a struct's member is referring
to a valid type, can only be done in the second pass. The second
verification pass will be implemented in the next patch.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Export data delivered and delivered with CE marks to
1) SNMP TCPDelivered and TCPDeliveredCE
2) getsockopt(TCP_INFO)
3) Timestamping API SOF_TIMESTAMPING_OPT_STATS
Note that for SCM_TSTAMP_ACK, the delivery info in
SOF_TIMESTAMPING_OPT_STATS is reported before the info
was fully updated on the ACK.
These stats help application monitor TCP delivery and ECN status
on per host, per connection, even per message level.
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Adding new bpf helper which would allow us to manipulate
xdp's data_end pointer, and allow us to reduce packet's size
indended use case: to generate ICMP messages from XDP context,
where such message would contain truncated original packet.
Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Like tos inherit, ttl inherit should also means inherit the inner protocol's
ttl values, which actually not implemented in vxlan yet.
But we could not treat ttl == 0 as "use the inner TTL", because that would be
used also when the "ttl" option is not specified and that would be a behavior
change, and breaking real use cases.
So add a different attribute IFLA_VXLAN_TTL_INHERIT when "ttl inherit" is
specified with ip cmd.
Reported-by: Jianlin Shi <jishi@redhat.com>
Suggested-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds missing values for the max read request size.
E.g. network driver r8169 uses a value of 4K.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
There were some documentation locations that irda was mentioned, as well
as an old MAINTAINERS entry and the networking sysctl entries. Clean
these all out as this stuff really is finally gone.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull parisc updates from Helge Deller:
- fix panic when halting system via "shutdown -h now"
- drop own coding in favour of generic CONFIG_COMPAT_BINFMT_ELF
implementation
- add FPE_CONDTRAP constant: last outstanding parisc-specific cleanup
for Eric Biedermans siginfo patches
- move some functions to .init and some to .text.hot linker sections
* 'parisc-4.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
parisc: Prevent panic at system halt
parisc: Switch to generic COMPAT_BINFMT_ELF
parisc: Move cache flush functions into .text.hot section
parisc/signal: Add FPE_CONDTRAP for conditional trap handling
Pull virtio update from Michael Tsirkin:
"This adds reporting hugepage stats to virtio-balloon"
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
virtio_balloon: export hugetlb page allocation counts
Patch series "linux/const.h: cleanups of macros such as UL(), _BITUL(),
BIT() etc", v3.
ARM, ARM64, UniCore32 define UL() as a shorthand of _AC(..., UL). More
architectures may introduce it in the future.
UL() is arch-agnostic, and useful. So let's move it to
include/linux/const.h
Currently, <asm/memory.h> must be included to use UL(). It pulls in more
bloats just for defining some bit macros.
I posted V2 one year ago.
The previous posts are:
https://patchwork.kernel.org/patch/9498273/https://patchwork.kernel.org/patch/9498275/https://patchwork.kernel.org/patch/9498269/https://patchwork.kernel.org/patch/9498271/
At that time, what blocked this series was a comment from
David Howells:
You need to be very careful doing this. Some userspace stuff
depends on the guard macro names on the kernel header files.
(https://patchwork.kernel.org/patch/9498275/)
Looking at the code closer, I noticed this is not a problem.
See the following line.
https://github.com/torvalds/linux/blob/v4.16-rc2/scripts/headers_install.sh#L40
scripts/headers_install.sh rips off _UAPI prefix from guard macro names.
I ran "make headers_install" and confirmed the result is what I expect.
So, we can prefix the include guard of include/uapi/linux/const.h,
and add a new include/linux/const.h.
This patch (of 4):
I am going to add include/linux/const.h for the kernel space.
Add _UAPI to the include guard of include/uapi/linux/const.h to
prepare for that.
Please notice the guard name of the exported one will be kept as-is.
So, this commit has no impact to the userspace even if some userspace
stuff depends on the guard macro names.
scripts/headers_install.sh processes exported headers by SED, and
rips off "_UAPI" from guard macro names.
#ifndef _UAPI_LINUX_CONST_H
#define _UAPI_LINUX_CONST_H
will be turned into
#ifndef _LINUX_CONST_H
#define _LINUX_CONST_H
Link: http://lkml.kernel.org/r/1519301715-31798-2-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Both load_elf_interp and load_elf_binary rely on elf_map to map segments
on a controlled address and they use MAP_FIXED to enforce that. This is
however dangerous thing prone to silent data corruption which can be
even exploitable.
Let's take CVE-2017-1000253 as an example. At the time (before commit
eab09532d4: "binfmt_elf: use ELF_ET_DYN_BASE only for PIE")
ELF_ET_DYN_BASE was at TASK_SIZE / 3 * 2 which is not that far away from
the stack top on 32b (legacy) memory layout (only 1GB away). Therefore
we could end up mapping over the existing stack with some luck.
The issue has been fixed since then (a87938b2e2: "fs/binfmt_elf.c: fix
bug in loading of PIE binaries"), ELF_ET_DYN_BASE moved moved much
further from the stack (eab09532d4 and later by c715b72c1b: "mm:
revert x86_64 and arm64 ELF_ET_DYN_BASE base changes") and excessive
stack consumption early during execve fully stopped by da029c11e6
("exec: Limit arg stack to at most 75% of _STK_LIM"). So we should be
safe and any attack should be impractical. On the other hand this is
just too subtle assumption so it can break quite easily and hard to
spot.
I believe that the MAP_FIXED usage in load_elf_binary (et. al) is still
fundamentally dangerous. Moreover it shouldn't be even needed. We are
at the early process stage and so there shouldn't be unrelated mappings
(except for stack and loader) existing so mmap for a given address should
succeed even without MAP_FIXED. Something is terribly wrong if this is
not the case and we should rather fail than silently corrupt the
underlying mapping.
Address this issue by changing MAP_FIXED to the newly added
MAP_FIXED_NOREPLACE. This will mean that mmap will fail if there is an
existing mapping clashing with the requested one without clobbering it.
[mhocko@suse.com: fix build]
[akpm@linux-foundation.org: coding-style fixes]
[avagin@openvz.org: don't use the same value for MAP_FIXED_NOREPLACE and MAP_SYNC]
Link: http://lkml.kernel.org/r/20171218184916.24445-1-avagin@openvz.org
Link: http://lkml.kernel.org/r/20171213092550.2774-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: introduce MAP_FIXED_NOREPLACE", v2.
This has started as a follow up discussion [3][4] resulting in the
runtime failure caused by hardening patch [5] which removes MAP_FIXED
from the elf loader because MAP_FIXED is inherently dangerous as it
might silently clobber an existing underlying mapping (e.g. stack).
The reason for the failure is that some architectures enforce an
alignment for the given address hint without MAP_FIXED used (e.g. for
shared or file backed mappings).
One way around this would be excluding those archs which do alignment
tricks from the hardening [6]. The patch is really trivial but it has
been objected, rightfully so, that this screams for a more generic
solution. We basically want a non-destructive MAP_FIXED.
The first patch introduced MAP_FIXED_NOREPLACE which enforces the given
address but unlike MAP_FIXED it fails with EEXIST if the given range
conflicts with an existing one. The flag is introduced as a completely
new one rather than a MAP_FIXED extension because of the backward
compatibility. We really want a never-clobber semantic even on older
kernels which do not recognize the flag. Unfortunately mmap sucks
wrt flags evaluation because we do not EINVAL on unknown flags. On
those kernels we would simply use the traditional hint based semantic so
the caller can still get a different address (which sucks) but at least
not silently corrupt an existing mapping. I do not see a good way
around that. Except we won't export expose the new semantic to the
userspace at all.
It seems there are users who would like to have something like that.
Jemalloc has been mentioned by Michael Ellerman [7]
Florian Weimer has mentioned the following:
: glibc ld.so currently maps DSOs without hints. This means that the kernel
: will map right next to each other, and the offsets between them a completely
: predictable. We would like to change that and supply a random address in a
: window of the address space. If there is a conflict, we do not want the
: kernel to pick a non-random address. Instead, we would try again with a
: random address.
John Hubbard has mentioned CUDA example
: a) Searches /proc/<pid>/maps for a "suitable" region of available
: VA space. "Suitable" generally means it has to have a base address
: within a certain limited range (a particular device model might
: have odd limitations, for example), it has to be large enough, and
: alignment has to be large enough (again, various devices may have
: constraints that lead us to do this).
:
: This is of course subject to races with other threads in the process.
:
: Let's say it finds a region starting at va.
:
: b) Next it does:
: p = mmap(va, ...)
:
: *without* setting MAP_FIXED, of course (so va is just a hint), to
: attempt to safely reserve that region. If p != va, then in most cases,
: this is a failure (almost certainly due to another thread getting a
: mapping from that region before we did), and so this layer now has to
: call munmap(), before returning a "failure: retry" to upper layers.
:
: IMPROVEMENT: --> if instead, we could call this:
:
: p = mmap(va, ... MAP_FIXED_NOREPLACE ...)
:
: , then we could skip the munmap() call upon failure. This
: is a small thing, but it is useful here. (Thanks to Piotr
: Jaroszynski and Mark Hairgrove for helping me get that detail
: exactly right, btw.)
:
: c) After that, CUDA suballocates from p, via:
:
: q = mmap(sub_region_start, ... MAP_FIXED ...)
:
: Interestingly enough, "freeing" is also done via MAP_FIXED, and
: setting PROT_NONE to the subregion. Anyway, I just included (c) for
: general interest.
Atomic address range probing in the multithreaded programs in general
sounds like an interesting thing to me.
The second patch simply replaces MAP_FIXED use in elf loader by
MAP_FIXED_NOREPLACE. I believe other places which rely on MAP_FIXED
should follow. Actually real MAP_FIXED usages should be docummented
properly and they should be more of an exception.
[1] http://lkml.kernel.org/r/20171116101900.13621-1-mhocko@kernel.org
[2] http://lkml.kernel.org/r/20171129144219.22867-1-mhocko@kernel.org
[3] http://lkml.kernel.org/r/20171107162217.382cd754@canb.auug.org.au
[4] http://lkml.kernel.org/r/1510048229.12079.7.camel@abdul.in.ibm.com
[5] http://lkml.kernel.org/r/20171023082608.6167-1-mhocko@kernel.org
[6] http://lkml.kernel.org/r/20171113094203.aofz2e7kueitk55y@dhcp22.suse.cz
[7] http://lkml.kernel.org/r/87efp1w7vy.fsf@concordia.ellerman.id.au
This patch (of 2):
MAP_FIXED is used quite often to enforce mapping at the particular range.
The main problem of this flag is, however, that it is inherently dangerous
because it unmaps existing mappings covered by the requested range. This
can cause silent memory corruptions. Some of them even with serious
security implications. While the current semantic might be really
desiderable in many cases there are others which would want to enforce the
given range but rather see a failure than a silent memory corruption on a
clashing range. Please note that there is no guarantee that a given range
is obeyed by the mmap even when it is free - e.g. arch specific code is
allowed to apply an alignment.
Introduce a new MAP_FIXED_NOREPLACE flag for mmap to achieve this
behavior. It has the same semantic as MAP_FIXED wrt. the given address
request with a single exception that it fails with EEXIST if the requested
address is already covered by an existing mapping. We still do rely on
get_unmaped_area to handle all the arch specific MAP_FIXED treatment and
check for a conflicting vma after it returns.
The flag is introduced as a completely new one rather than a MAP_FIXED
extension because of the backward compatibility. We really want a
never-clobber semantic even on older kernels which do not recognize the
flag. Unfortunately mmap sucks wrt. flags evaluation because we do not
EINVAL on unknown flags. On those kernels we would simply use the
traditional hint based semantic so the caller can still get a different
address (which sucks) but at least not silently corrupt an existing
mapping. I do not see a good way around that.
[mpe@ellerman.id.au: fix whitespace]
[fail on clashing range with EEXIST as per Florian Weimer]
[set MAP_FIXED before round_hint_to_min as per Khalid Aziz]
Link: http://lkml.kernel.org/r/20171213092550.2774-2-mhocko@kernel.org
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Russell King - ARM Linux <linux@armlinux.org.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Jason Evans <jasone@google.com>
Cc: David Goldblatt <davidtgoldblatt@gmail.com>
Cc: Edward Tomasz Napierała <trasz@FreeBSD.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a permission discrepancy when consulting msq ipc object
metadata between /proc/sysvipc/msg (0444) and the MSG_STAT shmctl
command. The later does permission checks for the object vs S_IRUGO.
As such there can be cases where EACCESS is returned via syscall but the
info is displayed anyways in the procfs files.
While this might have security implications via info leaking (albeit no
writing to the msq metadata), this behavior goes way back and showing
all the objects regardless of the permissions was most likely an
overlook - so we are stuck with it. Furthermore, modifying either the
syscall or the procfs file can cause userspace programs to break (ie
ipcs). Some applications require getting the procfs info (without root
privileges) and can be rather slow in comparison with a syscall -- up to
500x in some reported cases for shm.
This patch introduces a new MSG_STAT_ANY command such that the msq ipc
object permissions are ignored, and only audited instead. In addition,
I've left the lsm security hook checks in place, as if some policy can
block the call, then the user has no other choice than just parsing the
procfs file.
Link: http://lkml.kernel.org/r/20180215162458.10059-4-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Reported-by: Robert Kettler <robert.kettler@outlook.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
