The FIB lookup example[1] show how the IP-header field tot_len
(iph->tot_len) is used as input to perform the MTU check.
This patch extend the BPF-helper bpf_check_mtu() with the same ability
to provide the length as user parameter input, via mtu_len parameter.
This still needs to be done before the bpf_check_mtu() helper API
becomes frozen.
[1] samples/bpf/xdp_fwd_kern.c
Fixes: 34b2021cc6 ("bpf: Add BPF-helper for MTU checking")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161521555850.3515614.6533850861569774444.stgit@firesoul
bpf_skb_adjust_room sets the inner_protocol as skb->protocol for packets
encapsulation. But that is not appropriate when pushing Ethernet header.
Add an option to further specify encap L2 type and set the inner_protocol
as ETH_P_TEB.
Suggested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Xuesen Huang <huangxuesen@kuaishou.com>
Signed-off-by: Zhiyong Cheng <chengzhiyong@kuaishou.com>
Signed-off-by: Li Wang <wangli09@kuaishou.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/bpf/20210304064046.6232-1-hxseverything@gmail.com
Allow to pass sk_lookup programs to PROG_TEST_RUN. User space
provides the full bpf_sk_lookup struct as context. Since the
context includes a socket pointer that can't be exposed
to user space we define that PROG_TEST_RUN returns the cookie
of the selected socket or zero in place of the socket pointer.
We don't support testing programs that select a reuseport socket,
since this would mean running another (unrelated) BPF program
from the sk_lookup test handler.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210303101816.36774-3-lmb@cloudflare.com
Abstract out the target parameter so that upcoming commits, more than
just the existing "helpers" target can be called to generate specific
portions of docs from the eBPF UAPI headers.
Signed-off-by: Joe Stringer <joe@cilium.io>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210302171947.2268128-10-joe@cilium.io
Based roughly on the following commits:
* Commit cb4d03ab49 ("bpf: Add generic support for lookup batch op")
* Commit 057996380a ("bpf: Add batch ops to all htab bpf map")
* Commit aa2e93b8e5 ("bpf: Add generic support for update and delete
batch ops")
Signed-off-by: Joe Stringer <joe@cilium.io>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Brian Vazquez <brianvv@google.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210302171947.2268128-9-joe@cilium.io
Commit 468e2f64d2 ("bpf: introduce BPF_PROG_QUERY command") originally
introduced this, but there have been several additions since then.
Unlike BPF_PROG_ATTACH, it appears that the sockmap progs are not able
to be queried so far.
Signed-off-by: Joe Stringer <joe@cilium.io>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210302171947.2268128-8-joe@cilium.io
Based on a brief read of the corresponding source code.
Signed-off-by: Joe Stringer <joe@cilium.io>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210302171947.2268128-7-joe@cilium.io
Commit b2197755b2 ("bpf: add support for persistent maps/progs")
contains the original implementation and git logs, used as reference for
this documentation.
Also pull in the filename restriction as documented in commit 6d8cb045cd
("bpf: comment why dots in filenames under BPF virtual FS are not allowed")
Signed-off-by: Joe Stringer <joe@cilium.io>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210302171947.2268128-5-joe@cilium.io
Document the meaning of the BPF_F_LOCK flag for the map lookup/update
descriptions. Based on commit 96049f3afd ("bpf: introduce BPF_F_LOCK
flag").
Signed-off-by: Joe Stringer <joe@cilium.io>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210302171947.2268128-4-joe@cilium.io
Introduce high-level descriptions of the intent and return codes of the
bpf() syscall commands. Subsequent patches may further flesh out the
content to provide a more useful programming reference.
Signed-off-by: Joe Stringer <joe@cilium.io>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210302171947.2268128-3-joe@cilium.io
These descriptions are present in the man-pages project from the
original submissions around 2015-2016. Import them so that they can be
kept up to date as developers extend the bpf syscall commands.
These descriptions follow the pattern used by scripts/bpf_helpers_doc.py
so that we can take advantage of the parser to generate more up-to-date
man page writing based upon these headers.
Some minor wording adjustments were made to make the descriptions
more consistent for the description / return format.
Signed-off-by: Joe Stringer <joe@cilium.io>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210302171947.2268128-2-joe@cilium.io
Co-authored-by: Alexei Starovoitov <ast@kernel.org>
Co-authored-by: Michael Kerrisk <mtk.manpages@gmail.com>
The bpf_for_each_map_elem() helper is introduced which
iterates all map elements with a callback function. The
helper signature looks like
long bpf_for_each_map_elem(map, callback_fn, callback_ctx, flags)
and for each map element, the callback_fn will be called. For example,
like hashmap, the callback signature may look like
long callback_fn(map, key, val, callback_ctx)
There are two known use cases for this. One is from upstream ([1]) where
a for_each_map_elem helper may help implement a timeout mechanism
in a more generic way. Another is from our internal discussion
for a firewall use case where a map contains all the rules. The packet
data can be compared to all these rules to decide allow or deny
the packet.
For array maps, users can already use a bounded loop to traverse
elements. Using this helper can avoid using bounded loop. For other
type of maps (e.g., hash maps) where bounded loop is hard or
impossible to use, this helper provides a convenient way to
operate on all elements.
For callback_fn, besides map and map element, a callback_ctx,
allocated on caller stack, is also passed to the callback
function. This callback_ctx argument can provide additional
input and allow to write to caller stack for output.
If the callback_fn returns 0, the helper will iterate through next
element if available. If the callback_fn returns 1, the helper
will stop iterating and returns to the bpf program. Other return
values are not used for now.
Currently, this helper is only available with jit. It is possible
to make it work with interpreter with so effort but I leave it
as the future work.
[1]: https://lore.kernel.org/bpf/20210122205415.113822-1-xiyou.wangcong@gmail.com/
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226204925.3884923-1-yhs@fb.com
Commit 34b2021cc6 ("bpf: Add BPF-helper for MTU checking") added an extra
blank line in bpf helper description. This will make bpf_helpers_doc.py stop
building bpf_helper_defs.h immediately after bpf_check_mtu(), which will
affect future added functions.
Fixes: 34b2021cc6 ("bpf: Add BPF-helper for MTU checking")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20210223131457.1378978-1-liuhangbin@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Commit 34b2021cc6 ("bpf: Add BPF-helper for MTU checking") added an extra
blank line in bpf helper description. This will make bpf_helpers_doc.py stop
building bpf_helper_defs.h immediately after bpf_check_mtu(), which will
affect future added functions.
Fixes: 34b2021cc6 ("bpf: Add BPF-helper for MTU checking")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20210223131457.1378978-1-liuhangbin@gmail.com
This BPF-helper bpf_check_mtu() works for both XDP and TC-BPF programs.
The SKB object is complex and the skb->len value (accessible from
BPF-prog) also include the length of any extra GRO/GSO segments, but
without taking into account that these GRO/GSO segments get added
transport (L4) and network (L3) headers before being transmitted. Thus,
this BPF-helper is created such that the BPF-programmer don't need to
handle these details in the BPF-prog.
The API is designed to help the BPF-programmer, that want to do packet
context size changes, which involves other helpers. These other helpers
usually does a delta size adjustment. This helper also support a delta
size (len_diff), which allow BPF-programmer to reuse arguments needed by
these other helpers, and perform the MTU check prior to doing any actual
size adjustment of the packet context.
It is on purpose, that we allow the len adjustment to become a negative
result, that will pass the MTU check. This might seem weird, but it's not
this helpers responsibility to "catch" wrong len_diff adjustments. Other
helpers will take care of these checks, if BPF-programmer chooses to do
actual size adjustment.
V14:
- Improve man-page desc of len_diff.
V13:
- Enforce flag BPF_MTU_CHK_SEGS cannot use len_diff.
V12:
- Simplify segment check that calls skb_gso_validate_network_len.
- Helpers should return long
V9:
- Use dev->hard_header_len (instead of ETH_HLEN)
- Annotate with unlikely req from Daniel
- Fix logic error using skb_gso_validate_network_len from Daniel
V6:
- Took John's advice and dropped BPF_MTU_CHK_RELAX
- Returned MTU is kept at L3-level (like fib_lookup)
V4: Lot of changes
- ifindex 0 now use current netdev for MTU lookup
- rename helper from bpf_mtu_check to bpf_check_mtu
- fix bug for GSO pkt length (as skb->len is total len)
- remove __bpf_len_adj_positive, simply allow negative len adj
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161287790461.790810.3429728639563297353.stgit@firesoul
The BPF-helpers for FIB lookup (bpf_xdp_fib_lookup and bpf_skb_fib_lookup)
can perform MTU check and return BPF_FIB_LKUP_RET_FRAG_NEEDED. The BPF-prog
don't know the MTU value that caused this rejection.
If the BPF-prog wants to implement PMTU (Path MTU Discovery) (rfc1191) it
need to know this MTU value for the ICMP packet.
Patch change lookup and result struct bpf_fib_lookup, to contain this MTU
value as output via a union with 'tot_len' as this is the value used for
the MTU lookup.
V5:
- Fixed uninit value spotted by Dan Carpenter.
- Name struct output member mtu_result
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/161287789952.790810.13134700381067698781.stgit@firesoul
This needs a new helper that:
- can work in a sleepable context (using sock_gen_cookie)
- takes a struct sock pointer and checks that it's not NULL
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210210111406.785541-2-revest@chromium.org
Since "92acdc58ab11 bpf, net: Rework cookie generator as per-cpu one"
socket cookies are not guaranteed to be non-decreasing. The
bpf_get_socket_cookie helper descriptions are currently specifying that
cookies are non-decreasing but we don't want users to rely on that.
Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20210210111406.785541-1-revest@chromium.org
Add per-program counter for number of times recursion prevention mechanism
was triggered and expose it via show_fdinfo and bpf_prog_info.
Teach bpftool to print it.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210210033634.62081-7-alexei.starovoitov@gmail.com
This adds two atomic opcodes, both of which include the BPF_FETCH
flag. XCHG without the BPF_FETCH flag would naturally encode
atomic_set. This is not supported because it would be of limited
value to userspace (it doesn't imply any barriers). CMPXCHG without
BPF_FETCH woulud be an atomic compare-and-write. We don't have such
an operation in the kernel so it isn't provided to BPF either.
There are two significant design decisions made for the CMPXCHG
instruction:
- To solve the issue that this operation fundamentally has 3
operands, but we only have two register fields. Therefore the
operand we compare against (the kernel's API calls it 'old') is
hard-coded to be R0. x86 has similar design (and A64 doesn't
have this problem).
A potential alternative might be to encode the other operand's
register number in the immediate field.
- The kernel's atomic_cmpxchg returns the old value, while the C11
userspace APIs return a boolean indicating the comparison
result. Which should BPF do? A64 returns the old value. x86 returns
the old value in the hard-coded register (and also sets a
flag). That means return-old-value is easier to JIT, so that's
what we use.
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210114181751.768687-8-jackmanb@google.com
The BPF_FETCH field can be set in bpf_insn.imm, for BPF_ATOMIC
instructions, in order to have the previous value of the
atomically-modified memory location loaded into the src register
after an atomic op is carried out.
Suggested-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210114181751.768687-7-jackmanb@google.com
A subsequent patch will add additional atomic operations. These new
operations will use the same opcode field as the existing XADD, with
the immediate discriminating different operations.
In preparation, rename the instruction mode BPF_ATOMIC and start
calling the zero immediate BPF_ADD.
This is possible (doesn't break existing valid BPF progs) because the
immediate field is currently reserved MBZ and BPF_ADD is zero.
All uses are removed from the tree but the BPF_XADD definition is
kept around to avoid breaking builds for people including kernel
headers.
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20210114181751.768687-5-jackmanb@google.com
When the buffer is too small to contain the input string, these helpers
return the length of the buffer, not the length of the original string.
This tries to make the docs totally clear about that, since "the length
of the [copied ]string" could also refer to the length of the input.
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: KP Singh <kpsingh@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210112123422.2011234-1-jackmanb@google.com
Daniel Borkmann says:
====================
pull-request: bpf-next 2020-12-14
1) Expose bpf_sk_storage_*() helpers to iterator programs, from Florent Revest.
2) Add AF_XDP selftests based on veth devs to BPF selftests, from Weqaar Janjua.
3) Support for finding BTF based kernel attach targets through libbpf's
bpf_program__set_attach_target() API, from Andrii Nakryiko.
4) Permit pointers on stack for helper calls in the verifier, from Yonghong Song.
5) Fix overflows in hash map elem size after rlimit removal, from Eric Dumazet.
6) Get rid of direct invocation of llc in BPF selftests, from Andrew Delgadillo.
7) Fix xsk_recvmsg() to reorder socket state check before access, from Björn Töpel.
8) Add new libbpf API helper to retrieve ring buffer epoll fd, from Brendan Jackman.
9) Batch of minor BPF selftest improvements all over the place, from Florian Lehner,
KP Singh, Jiri Olsa and various others.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (31 commits)
selftests/bpf: Add a test for ptr_to_map_value on stack for helper access
bpf: Permits pointers on stack for helper calls
libbpf: Expose libbpf ring_buffer epoll_fd
selftests/bpf: Add set_attach_target() API selftest for module target
libbpf: Support modules in bpf_program__set_attach_target() API
selftests/bpf: Silence ima_setup.sh when not running in verbose mode.
selftests/bpf: Drop the need for LLVM's llc
selftests/bpf: fix bpf_testmod.ko recompilation logic
samples/bpf: Fix possible hang in xdpsock with multiple threads
selftests/bpf: Make selftest compilation work on clang 11
selftests/bpf: Xsk selftests - adding xdpxceiver to .gitignore
selftests/bpf: Drop tcp-{client,server}.py from Makefile
selftests/bpf: Xsk selftests - Bi-directional Sockets - SKB, DRV
selftests/bpf: Xsk selftests - Socket Teardown - SKB, DRV
selftests/bpf: Xsk selftests - DRV POLL, NOPOLL
selftests/bpf: Xsk selftests - SKB POLL, NOPOLL
selftests/bpf: Xsk selftests framework
bpf: Only provide bpf_sock_from_file with CONFIG_NET
bpf: Return -ENOTSUPP when attaching to non-kernel BTF
xsk: Validate socket state in xsk_recvmsg, prior touching socket members
...
====================
Link: https://lore.kernel.org/r/20201214214316.20642-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
xdp_return_frame_bulk() needs to pass a xdp_buff
to __xdp_return().
strlcpy got converted to strscpy but here it makes no
functional difference, so just keep the right code.
Conflicts:
net/netfilter/nf_tables_api.c
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Remove bpf_ prefix, which causes these helpers to be reported in verifier
dump as bpf_bpf_this_cpu_ptr() and bpf_bpf_per_cpu_ptr(), respectively. Lets
fix it as long as it is still possible before UAPI freezes on these helpers.
Fixes: eaa6bcb71e ("bpf: Introduce bpf_per_cpu_ptr()")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While eBPF programs can check whether a file is a socket by file->f_op
== &socket_file_ops, they cannot convert the void private_data pointer
to a struct socket BTF pointer. In order to do this a new helper
wrapping sock_from_file is added.
This is useful to tracing programs but also other program types
inheriting this set of helpers such as iterators or LSM programs.
Signed-off-by: Florent Revest <revest@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: KP Singh <kpsingh@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20201204113609.1850150-2-revest@google.com
Add ability for user-space programs to specify non-vmlinux BTF when attaching
BTF-powered BPF programs: raw_tp, fentry/fexit/fmod_ret, LSM, etc. For this,
attach_prog_fd (now with the alias name attach_btf_obj_fd) should specify FD
of a module or vmlinux BTF object. For backwards compatibility reasons,
0 denotes vmlinux BTF. Only kernel BTF (vmlinux or module) can be specified.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201203204634.1325171-11-andrii@kernel.org
Provide a wrapper function to get the IMA hash of an inode. This helper
is useful in fingerprinting files (e.g executables on execution) and
using these fingerprints in detections like an executable unlinking
itself.
Since the ima_inode_hash can sleep, it's only allowed for sleepable
LSM hooks.
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20201124151210.1081188-3-kpsingh@chromium.org
The helper uses CLOCK_MONOTONIC_COARSE source of time that is less
accurate but more performant.
We have a BPF CGROUP_SKB firewall that supports event logging through
bpf_perf_event_output(). Each event has a timestamp and currently we use
bpf_ktime_get_ns() for it. Use of bpf_ktime_get_coarse_ns() saves ~15-20
ns in time required for event logging.
bpf_ktime_get_ns():
EgressLogByRemoteEndpoint 113.82ns 8.79M
bpf_ktime_get_coarse_ns():
EgressLogByRemoteEndpoint 95.40ns 10.48M
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20201117184549.257280-1-me@ubique.spb.ru
The helper allows modification of certain bits on the linux_binprm
struct starting with the secureexec bit which can be updated using the
BPF_F_BPRM_SECUREEXEC flag.
secureexec can be set by the LSM for privilege gaining executions to set
the AT_SECURE auxv for glibc. When set, the dynamic linker disables the
use of certain environment variables (like LD_PRELOAD).
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20201117232929.2156341-1-kpsingh@chromium.org
Allocate ID for vmlinux BTF. This makes it visible when iterating over all BTF
objects in the system. To allow distinguishing vmlinux BTF (and later kernel
module BTF) from user-provided BTFs, expose extra kernel_btf flag, as well as
BTF name ("vmlinux" for vmlinux BTF, will equal to module's name for module
BTF). We might want to later allow specifying BTF name for user-provided BTFs
as well, if that makes sense. But currently this is reserved only for
in-kernel BTFs.
Having in-kernel BTFs exposed IDs will allow to extend BPF APIs that require
in-kernel BTF type with ability to specify BTF types from kernel modules, not
just vmlinux BTF. This will be implemented in a follow up patch set for
fentry/fexit/fmod_ret/lsm/etc.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20201110011932.3201430-3-andrii@kernel.org
The currently available bpf_get_current_task returns an unsigned integer
which can be used along with BPF_CORE_READ to read data from
the task_struct but still cannot be used as an input argument to a
helper that accepts an ARG_PTR_TO_BTF_ID of type task_struct.
In order to implement this helper a new return type, RET_PTR_TO_BTF_ID,
is added. This is similar to RET_PTR_TO_BTF_ID_OR_NULL but does not
require checking the nullness of returned pointer.
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20201106103747.2780972-6-kpsingh@chromium.org
Similar to bpf_local_storage for sockets and inodes add local storage
for task_struct.
The life-cycle of storage is managed with the life-cycle of the
task_struct. i.e. the storage is destroyed along with the owning task
with a callback to the bpf_task_storage_free from the task_free LSM
hook.
The BPF LSM allocates an __rcu pointer to the bpf_local_storage in
the security blob which are now stackable and can co-exist with other
LSMs.
The userspace map operations can be done by using a pid fd as a key
passed to the lookup, update and delete operations.
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20201106103747.2780972-3-kpsingh@chromium.org
Based on the discussion in [0], update the bpf_redirect_neigh() helper to
accept an optional parameter specifying the nexthop information. This makes
it possible to combine bpf_fib_lookup() and bpf_redirect_neigh() without
incurring a duplicate FIB lookup - since the FIB lookup helper will return
the nexthop information even if no neighbour is present, this can simply
be passed on to bpf_redirect_neigh() if bpf_fib_lookup() returns
BPF_FIB_LKUP_RET_NO_NEIGH. Thus fix & extend it before helper API is frozen.
[0] https://lore.kernel.org/bpf/393e17fc-d187-3a8d-2f0d-a627c7c63fca@iogearbox.net/
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/bpf/160322915615.32199.1187570224032024535.stgit@toke.dk
Recent work in f4d0525921 ("bpf: Add map_meta_equal map ops") and 134fede4ee
("bpf: Relax max_entries check for most of the inner map types") added support
for dynamic inner max elements for most map-in-map types. Exceptions were maps
like array or prog array where the map_gen_lookup() callback uses the maps'
max_entries field as a constant when emitting instructions.
We recently implemented Maglev consistent hashing into Cilium's load balancer
which uses map-in-map with an outer map being hash and inner being array holding
the Maglev backend table for each service. This has been designed this way in
order to reduce overall memory consumption given the outer hash map allows to
avoid preallocating a large, flat memory area for all services. Also, the
number of service mappings is not always known a-priori.
The use case for dynamic inner array map entries is to further reduce memory
overhead, for example, some services might just have a small number of back
ends while others could have a large number. Right now the Maglev backend table
for small and large number of backends would need to have the same inner array
map entries which adds a lot of unneeded overhead.
Dynamic inner array map entries can be realized by avoiding the inlined code
generation for their lookup. The lookup will still be efficient since it will
be calling into array_map_lookup_elem() directly and thus avoiding retpoline.
The patch adds a BPF_F_INNER_MAP flag to map creation which therefore skips
inline code generation and relaxes array_map_meta_equal() check to ignore both
maps' max_entries. This also still allows to have faster lookups for map-in-map
when BPF_F_INNER_MAP is not specified and hence dynamic max_entries not needed.
Example code generation where inner map is dynamic sized array:
# bpftool p d x i 125
int handle__sys_enter(void * ctx):
; int handle__sys_enter(void *ctx)
0: (b4) w1 = 0
; int key = 0;
1: (63) *(u32 *)(r10 -4) = r1
2: (bf) r2 = r10
;
3: (07) r2 += -4
; inner_map = bpf_map_lookup_elem(&outer_arr_dyn, &key);
4: (18) r1 = map[id:468]
6: (07) r1 += 272
7: (61) r0 = *(u32 *)(r2 +0)
8: (35) if r0 >= 0x3 goto pc+5
9: (67) r0 <<= 3
10: (0f) r0 += r1
11: (79) r0 = *(u64 *)(r0 +0)
12: (15) if r0 == 0x0 goto pc+1
13: (05) goto pc+1
14: (b7) r0 = 0
15: (b4) w6 = -1
; if (!inner_map)
16: (15) if r0 == 0x0 goto pc+6
17: (bf) r2 = r10
;
18: (07) r2 += -4
; val = bpf_map_lookup_elem(inner_map, &key);
19: (bf) r1 = r0 | No inlining but instead
20: (85) call array_map_lookup_elem#149280 | call to array_map_lookup_elem()
; return val ? *val : -1; | for inner array lookup.
21: (15) if r0 == 0x0 goto pc+1
; return val ? *val : -1;
22: (61) r6 = *(u32 *)(r0 +0)
; }
23: (bc) w0 = w6
24: (95) exit
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20201010234006.7075-4-daniel@iogearbox.net
Add an efficient ingress to ingress netns switch that can be used out of tc BPF
programs in order to redirect traffic from host ns ingress into a container
veth device ingress without having to go via CPU backlog queue [0]. For local
containers this can also be utilized and path via CPU backlog queue only needs
to be taken once, not twice. On a high level this borrows from ipvlan which does
similar switch in __netif_receive_skb_core() and then iterates via another_round.
This helps to reduce latency for mentioned use cases.
Pod to remote pod with redirect(), TCP_RR [1]:
# percpu_netperf 10.217.1.33
RT_LATENCY: 122.450 (per CPU: 122.666 122.401 122.333 122.401 )
MEAN_LATENCY: 121.210 (per CPU: 121.100 121.260 121.320 121.160 )
STDDEV_LATENCY: 120.040 (per CPU: 119.420 119.910 125.460 115.370 )
MIN_LATENCY: 46.500 (per CPU: 47.000 47.000 47.000 45.000 )
P50_LATENCY: 118.500 (per CPU: 118.000 119.000 118.000 119.000 )
P90_LATENCY: 127.500 (per CPU: 127.000 128.000 127.000 128.000 )
P99_LATENCY: 130.750 (per CPU: 131.000 131.000 129.000 132.000 )
TRANSACTION_RATE: 32666.400 (per CPU: 8152.200 8169.842 8174.439 8169.897 )
Pod to remote pod with redirect_peer(), TCP_RR:
# percpu_netperf 10.217.1.33
RT_LATENCY: 44.449 (per CPU: 43.767 43.127 45.279 45.622 )
MEAN_LATENCY: 45.065 (per CPU: 44.030 45.530 45.190 45.510 )
STDDEV_LATENCY: 84.823 (per CPU: 66.770 97.290 84.380 90.850 )
MIN_LATENCY: 33.500 (per CPU: 33.000 33.000 34.000 34.000 )
P50_LATENCY: 43.250 (per CPU: 43.000 43.000 43.000 44.000 )
P90_LATENCY: 46.750 (per CPU: 46.000 47.000 47.000 47.000 )
P99_LATENCY: 52.750 (per CPU: 51.000 54.000 53.000 53.000 )
TRANSACTION_RATE: 90039.500 (per CPU: 22848.186 23187.089 22085.077 21919.130 )
[0] https://linuxplumbersconf.org/event/7/contributions/674/attachments/568/1002/plumbers_2020_cilium_load_balancer.pdf
[1] https://github.com/borkmann/netperf_scripts/blob/master/percpu_netperf
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201010234006.7075-3-daniel@iogearbox.net
Follow-up to address David's feedback that we should better describe internals
of the bpf_redirect_neigh() helper.
Suggested-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: David Ahern <dsahern@gmail.com>
Link: https://lore.kernel.org/bpf/20201010234006.7075-2-daniel@iogearbox.net
Add bpf_this_cpu_ptr() to help access percpu var on this cpu. This
helper always returns a valid pointer, therefore no need to check
returned value for NULL. Also note that all programs run with
preemption disabled, which means that the returned pointer is stable
during all the execution of the program.
Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200929235049.2533242-6-haoluo@google.com
Add bpf_per_cpu_ptr() to help bpf programs access percpu vars.
bpf_per_cpu_ptr() has the same semantic as per_cpu_ptr() in the kernel
except that it may return NULL. This happens when the cpu parameter is
out of range. So the caller must check the returned value.
Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200929235049.2533242-5-haoluo@google.com
Pseudo_btf_id is a type of ld_imm insn that associates a btf_id to a
ksym so that further dereferences on the ksym can use the BTF info
to validate accesses. Internally, when seeing a pseudo_btf_id ld insn,
the verifier reads the btf_id stored in the insn[0]'s imm field and
marks the dst_reg as PTR_TO_BTF_ID. The btf_id points to a VAR_KIND,
which is encoded in btf_vminux by pahole. If the VAR is not of a struct
type, the dst reg will be marked as PTR_TO_MEM instead of PTR_TO_BTF_ID
and the mem_size is resolved to the size of the VAR's type.
>From the VAR btf_id, the verifier can also read the address of the
ksym's corresponding kernel var from kallsyms and use that to fill
dst_reg.
Therefore, the proper functionality of pseudo_btf_id depends on (1)
kallsyms and (2) the encoding of kernel global VARs in pahole, which
should be available since pahole v1.18.
Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200929235049.2533242-2-haoluo@google.com
Currently, perf event in perf event array is removed from the array when
the map fd used to add the event is closed. This behavior makes it
difficult to the share perf events with perf event array.
Introduce perf event map that keeps the perf event open with a new flag
BPF_F_PRESERVE_ELEMS. With this flag set, perf events in the array are not
removed when the original map fd is closed. Instead, the perf event will
stay in the map until 1) it is explicitly removed from the array; or 2)
the array is freed.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200930224927.1936644-2-songliubraving@fb.com
Add a redirect_neigh() helper as redirect() drop-in replacement
for the xmit side. Main idea for the helper is to be very similar
in semantics to the latter just that the skb gets injected into
the neighboring subsystem in order to let the stack do the work
it knows best anyway to populate the L2 addresses of the packet
and then hand over to dev_queue_xmit() as redirect() does.
This solves two bigger items: i) skbs don't need to go up to the
stack on the host facing veth ingress side for traffic egressing
the container to achieve the same for populating L2 which also
has the huge advantage that ii) the skb->sk won't get orphaned in
ip_rcv_core() when entering the IP routing layer on the host stack.
Given that skb->sk neither gets orphaned when crossing the netns
as per 9c4c325252 ("skbuff: preserve sock reference when scrubbing
the skb.") the helper can then push the skbs directly to the phys
device where FQ scheduler can do its work and TCP stack gets proper
backpressure given we hold on to skb->sk as long as skb is still
residing in queues.
With the helper used in BPF data path to then push the skb to the
phys device, I observed a stable/consistent TCP_STREAM improvement
on veth devices for traffic going container -> host -> host ->
container from ~10Gbps to ~15Gbps for a single stream in my test
environment.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: David Ahern <dsahern@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Cc: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/bpf/f207de81629e1724899b73b8112e0013be782d35.1601477936.git.daniel@iogearbox.net
Similarly to 5a52ae4e32 ("bpf: Allow to retrieve cgroup v1 classid
from v2 hooks"), add a helper to retrieve cgroup v1 classid solely
based on the skb->sk, so it can be used as key as part of BPF map
lookups out of tc from host ns, in particular given the skb->sk is
retained these days when crossing net ns thanks to 9c4c325252
("skbuff: preserve sock reference when scrubbing the skb."). This
is similar to bpf_skb_cgroup_id() which implements the same for v2.
Kubernetes ecosystem is still operating on v1 however, hence net_cls
needs to be used there until this can be dropped in with the v2
helper of bpf_skb_cgroup_id().
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/ed633cf27a1c620e901c5aa99ebdefb028dce600.1601477936.git.daniel@iogearbox.net
This enables support for attaching freplace programs to multiple attach
points. It does this by amending the UAPI for bpf_link_Create with a target
btf ID that can be used to supply the new attachment point along with the
target program fd. The target must be compatible with the target that was
supplied at program load time.
The implementation reuses the checks that were factored out of
check_attach_btf_id() to ensure compatibility between the BTF types of the
old and new attachment. If these match, a new bpf_tracing_link will be
created for the new attach target, allowing multiple attachments to
co-exist simultaneously.
The code could theoretically support multiple-attach of other types of
tracing programs as well, but since I don't have a use case for any of
those, there is no API support for doing so.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/160138355169.48470.17165680973640685368.stgit@toke.dk
A helper is added to allow seq file writing of kernel data
structures using vmlinux BTF. Its signature is
long bpf_seq_printf_btf(struct seq_file *m, struct btf_ptr *ptr,
u32 btf_ptr_size, u64 flags);
Flags and struct btf_ptr definitions/use are identical to the
bpf_snprintf_btf helper, and the helper returns 0 on success
or a negative error value.
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1601292670-1616-8-git-send-email-alan.maguire@oracle.com
David S. Miller