Now we can implement unix_bpf_update_proto() to update
sk_prot, especially prot->close().
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210704190252.11866-7-xiyou.wangcong@gmail.com

Unlike af_inet, unix_proto is very different, it does not even
have a ->close(). We have to add a dummy implementation to
satisfy sockmap. Normally it is just a nop, it is introduced only
for sockmap to replace it.
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210704190252.11866-6-xiyou.wangcong@gmail.com

Currently only unix stream socket sets TCP_ESTABLISHED,
datagram socket can set this too when they connect to its
peer socket. At least __ip4_datagram_connect() does the same.

This will be used to determine whether an AF_UNIX datagram
socket can be redirected to in sockmap.
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210704190252.11866-5-xiyou.wangcong@gmail.com

Implement ->read_sock() for AF_UNIX datagram socket, it is
pretty much similar to udp_read_sock().
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210704190252.11866-4-xiyou.wangcong@gmail.com

TCP and other connection oriented sockets have accept()
for each incoming connection on the server side, hence
they can just insert those fd's from accept() to sockmap,
which are of course established.

Now with datagram sockets begin to support sockmap and
redirection, the restriction is no longer applicable to
them, as they have no accept(). So we have to lift this
restriction for them. This is fine, because inside
bpf_sk_redirect_map() we still have another socket status
check, sock_map_redirect_allowed(), as a guard.

This also means they do not have to be removed from
sockmap when disconnecting.
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210704190252.11866-3-xiyou.wangcong@gmail.com

Currently sock_map still has Kconfig dependency on CONFIG_INET,
but there is no actual functional dependency on it after we
introduce ->psock_update_sk_prot().

We have to extend it to CONFIG_NET now as we are going to
support AF_UNIX.
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210704190252.11866-2-xiyou.wangcong@gmail.com

Jiri Olsa says:

====================
Add bpf_get_func_ip helper that returns IP address of the
caller function for trampoline and krobe programs.

There're 2 specific implementation of the bpf_get_func_ip
helper, one for trampoline progs and one for kprobe/kretprobe
progs.

The trampoline helper call is replaced/inlined by the verifier
with simple move instruction. The kprobe/kretprobe is actual
helper call that returns prepared caller address.

Also available at:
  https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
  bpf/get_func_ip

v4 changes:
  - dropped jit/x86 check for get_func_ip tracing check [Alexei]
  - added code to bpf_get_func_ip_tracing [Alexei]
    and tested that it works without inlining [Alexei]
  - changed has_get_func_ip to check_get_func_ip [Andrii]
  - replaced test assert loop with explicit asserts [Andrii]
  - adde bpf_program__attach_kprobe_opts function
    and use it for offset setup [Andrii]
  - used bpf_program__set_autoload(false) for test6 [Andrii]
  - added Masami's ack

v3 changes:
  - resend with Masami in cc and v3 in each patch subject

v2 changes:
  - use kprobe_running to get kprobe instead of cpu var [Masami]
  - added support to add kprobe on function+offset
    and test for that [Alan]
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Adding test for bpf_get_func_ip in kprobe+ofset probe.
Because of the offset value it's arch specific, enabling
the new test only for x86_64 architecture.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-9-jolsa@kernel.org

kprobes can be placed on most instructions in a function, not
just entry, and ftrace and bpftrace support the function+offset
notification for probe placement.  Adding parsing of func_name
into func+offset to bpf_program__attach_kprobe() allows the
user to specify

SEC("kprobe/bpf_fentry_test5+0x6")

...for example, and the offset can be passed to perf_event_open_probe()
to support kprobe attachment.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-8-jolsa@kernel.org

Adding bpf_program__attach_kprobe_opts that does the same
as bpf_program__attach_kprobe, but takes opts argument.

Currently opts struct holds just retprobe bool, but we will
add new field in following patch.

The function is not exported, so there's no need to add
size to the struct bpf_program_attach_kprobe_opts for now.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-7-jolsa@kernel.org

Adding test for bpf_get_func_ip helper for fentry, fexit,
kprobe, kretprobe and fmod_ret programs.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-6-jolsa@kernel.org

Adding bpf_get_func_ip helper for BPF_PROG_TYPE_KPROBE programs,
so it's now possible to call bpf_get_func_ip from both kprobe and
kretprobe programs.

Taking the caller's address from 'struct kprobe::addr', which is
defined for both kprobe and kretprobe.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-5-jolsa@kernel.org

Adding bpf_get_func_ip helper for BPF_PROG_TYPE_TRACING programs,
specifically for all trampoline attach types.

The trampoline's caller IP address is stored in (ctx - 8) address.
so there's no reason to actually call the helper, but rather fixup
the call instruction and return [ctx - 8] value directly.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-4-jolsa@kernel.org

Enabling BPF_TRAMP_F_IP_ARG for trampolines that actually need it.

The BPF_TRAMP_F_IP_ARG adds extra 3 instructions to trampoline code
and is used only by programs with bpf_get_func_ip helper, which is
added in following patch and sets call_get_func_ip bit.

This patch ensures that BPF_TRAMP_F_IP_ARG flag is used only for
trampolines that have programs with call_get_func_ip set.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-3-jolsa@kernel.org

Storing caller's ip in trampoline's stack. Trampoline programs
can reach the IP in (ctx - 8) address, so there's no change in
program's arguments interface.

The IP address is takes from [fp + 8], which is return address
from the initial 'call fentry' call to trampoline.

This IP address will be returned via bpf_get_func_ip helper
helper, which is added in following patches.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-2-jolsa@kernel.org

Alexei Starovoitov says:

====================
The first request to support timers in bpf was made in 2013 before sys_bpf
syscall was added. That use case was periodic sampling. It was address with
attaching bpf programs to perf_events. Then during XDP development the timers
were requested to do garbage collection and health checks. They were worked
around by implementing timers in user space and triggering progs with
BPF_PROG_RUN command. The user space timers and perf_event+bpf timers are not
armed by the bpf program. They're done asynchronously vs program execution.
The XDP program cannot send a packet and arm the timer at the same time. The
tracing prog cannot record an event and arm the timer right away. This large
class of use cases remained unaddressed. The jiffy based and hrtimer based
timers are essential part of the kernel development and with this patch set
the hrtimer based timers will be available to bpf programs.

TLDR: bpf timers is a wrapper of hrtimers with all the extra safety added
to make sure bpf progs cannot crash the kernel.

v6->v7:
- address Andrii's comments and add his Acks.

v5->v6:
- address code review feedback from Martin and add his Acks.
- add usercnt > 0 check to bpf_timer_init and remove timers_cancel_and_free
second loop in map_free callbacks.
- add cond_resched_rcu.

v4->v5:
- Martin noticed the following issues:
. prog could be reallocated bpf_patch_insn_data().
Fixed by passing 'aux' into bpf_timer_set_callback, since 'aux' is stable
during insn patching.
. Added missing rcu_read_lock.
. Removed redundant record_map.
- Discovered few bugs with stress testing:
. One cpu does htab_free_prealloced_timers->bpf_timer_cancel_and_free->hrtimer_cancel
while another is trying to do something with the timer like bpf_timer_start/set_callback.
Those ops try to acquire bpf_spin_lock that is already taken by bpf_timer_cancel_and_free,
so both cpus spin forever. The same problem existed in bpf_timer_cancel().
One bpf prog on one cpu might call bpf_timer_cancel and wait, while another cpu is in
the timer callback that tries to do bpf_timer_*() helper on the same timer.
The fix is to do drop_prog_refcnt() and unlock. And only then hrtimer_cancel.
Because of this had to add callback_fn != NULL check to bpf_timer_cb().
Also removed redundant bpf_prog_inc/put from bpf_timer_cb() and replaced
with rcu_dereference_check similar to recent rcu_read_lock-removal from drivers.
bpf_timer_cb is in softirq.
. Managed to hit refcnt==0 while doing bpf_prog_put from bpf_timer_cancel_and_free().
That exposed the issue that bpf_prog_put wasn't ready to be called from irq context.
Fixed similar to bpf_map_put which is irq ready.
- Refactored BPF_CALL_1(bpf_spin_lock) into __bpf_spin_lock_irqsave() to
make the main logic more clear, since Martin and Yonghong brought up this concern.

v3->v4:
1.
Split callback_fn from bpf_timer_start into bpf_timer_set_callback as
suggested by Martin. That makes bpf timer api match one to one to
kernel hrtimer api and provides greater flexibility.
2.
Martin also discovered the following issue with uref approach:
bpftool prog load xdp_timer.o /sys/fs/bpf/xdp_timer type xdp
bpftool net attach xdpgeneric pinned /sys/fs/bpf/xdp_timer dev lo
rm /sys/fs/bpf/xdp_timer
nc -6 ::1 8888
bpftool net detach xdpgeneric dev lo
The timer callback stays active in the kernel though the prog was detached
and map usercnt == 0.
It happened because 'bpftool prog load' pinned the prog only.
The map usercnt went to zero. Subsequent attach and runs didn't
affect map usercnt. The timer was able to start and bpf_prog_inc itself.
When the prog was detached the prog stayed active.
To address this issue added
if (!atomic64_read(&(t->map->usercnt))) return -EPERM;
to the first patch.
Which means that timers are allowed only in the maps that are held
by user space with open file descriptor or maps pinned in bpffs.
3.
Discovered that timers in inner maps were broken.
The inner map pointers are dynamic. Therefore changed bpf_timer_init()
to accept explicit map pointer supplied by the program instead
of hidden map pointer supplied by the verifier.
To make sure that pointer to a timer actually belongs to that map
added the verifier check in patch 3.
4.
Addressed Yonghong's feedback. Improved comments and added
dynamic in_nmi() check.
Added Acks.

v2->v3:
The v2 approach attempted to bump bpf_prog refcnt when bpf_timer_start is
called to make sure callback code doesn't disappear when timer is active and
drop refcnt when timer cb is done. That led to a ton of race conditions between
callback running and concurrent bpf_timer_init/start/cancel on another cpu,
and concurrent bpf_map_update/delete_elem, and map destroy.

Then v2.5 approach skipped prog refcnt altogether. Instead it remembered all
timers that bpf prog armed in a link list and canceled them when prog refcnt
went to zero. The race conditions disappeared, but timers in map-in-map could
not be supported cleanly, since timers in inner maps have inner map's life time
and don't match prog's life time.

This v3 approach makes timers to be owned by maps. It allows timers in inner
maps to be supported from the start. This apporach relies on "user refcnt"
scheme used in prog_array that stores bpf programs for bpf_tail_call. The
bpf_timer_start() increments prog refcnt, but unlike 1st approach the timer
callback does decrement the refcnt. The ops->map_release_uref is
responsible for cancelling the timers and dropping prog refcnt when user space
reference to a map is dropped. That addressed all the races and simplified
locking.

Andrii presented a use case where specifying callback_fn in bpf_timer_init()
is inconvenient vs specifying in bpf_timer_start(). The bpf_timer_init()
typically is called outside for timer callback, while bpf_timer_start() most
likely will be called from the callback.
timer_cb() { ... bpf_timer_start(timer_cb); ...} looks like recursion and as
infinite loop to the verifier. The verifier had to be made smarter to recognize
such async callbacks. Patches 7,8,9 addressed that.

Patch 1 and 2 refactoring.
Patch 3 implements bpf timer helpers and locking.
Patch 4 implements map side of bpf timer support.
Patch 5 prevent pointer mismatch in bpf_timer_init.
Patch 6 adds support for BTF in inner maps.
Patch 7 teaches check_cfg() pass to understand async callbacks.
Patch 8 teaches do_check() pass to understand async callbacks.
Patch 9 teaches check_max_stack_depth() pass to understand async callbacks.
Patches 10 and 11 are the tests.

v1->v2:
- Addressed great feedback from Andrii and Toke.
- Fixed race between parallel bpf_timer_*() ops.
- Fixed deadlock between timer callback and LRU eviction or bpf_map_delete/update.
- Disallowed mmap and global timers.
- Allow spin_lock and bpf_timer in an element.
- Fixed memory leaks due to map destruction and LRU eviction.
- A ton more tests.
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Check that map-in-map supports bpf timers.

Check that indirect "recursion" of timer callbacks works:
timer_cb1() { bpf_timer_set_callback(timer_cb2); }
timer_cb2() { bpf_timer_set_callback(timer_cb1); }

Check that
  bpf_map_release
    htab_free_prealloced_timers
      bpf_timer_cancel_and_free
        hrtimer_cancel
works while timer cb is running.
"while true; do ./test_progs -t timer_mim; done"
is a great stress test. It caught missing timer cancel in htab->extra_elems.

timer_mim_reject.c is a negative test that checks
that timer<->map mismatch is prevented.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-12-alexei.starovoitov@gmail.com

Add bpf_timer test that creates timers in preallocated and
non-preallocated hash, in array and in lru maps.
Let array timer expire once and then re-arm it for 35 seconds.
Arm lru timer into the same callback.
Then arm and re-arm hash timers 10 times each.
At the last invocation of prealloc hash timer cancel the array timer.
Force timer free via LRU eviction and direct bpf_map_delete_elem.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-11-alexei.starovoitov@gmail.com

Teach max stack depth checking algorithm about async callbacks
that don't increase bpf program stack size.
Also add sanity check that bpf_tail_call didn't sneak into async cb.
It's impossible, since PTR_TO_CTX is not available in async cb,
hence the program cannot contain bpf_tail_call(ctx,...);
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-10-alexei.starovoitov@gmail.com

bpf_for_each_map_elem() and bpf_timer_set_callback() helpers are relying on
PTR_TO_FUNC infra in the verifier to validate addresses to subprograms
and pass them into the helpers as function callbacks.
In case of bpf_for_each_map_elem() the callback is invoked synchronously
and the verifier treats it as a normal subprogram call by adding another
bpf_func_state and new frame in __check_func_call().
bpf_timer_set_callback() doesn't invoke the callback directly.
The subprogram will be called asynchronously from bpf_timer_cb().
Teach the verifier to validate such async callbacks as special kind
of jump by pushing verifier state into stack and let pop_stack() process it.

Special care needs to be taken during state pruning.
The call insn doing bpf_timer_set_callback has to be a prune_point.
Otherwise short timer callbacks might not have prune points in front of
bpf_timer_set_callback() which means is_state_visited() will be called
after this call insn is processed in __check_func_call(). Which means that
another async_cb state will be pushed to be walked later and the verifier
will eventually hit BPF_COMPLEXITY_LIMIT_JMP_SEQ limit.
Since push_async_cb() looks like another push_stack() branch the
infinite loop detection will trigger false positive. To recognize
this case mark such states as in_async_callback_fn.
To distinguish infinite loop in async callback vs the same callback called
with different arguments for different map and timer add async_entry_cnt
to bpf_func_state.

Enforce return zero from async callbacks.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-9-alexei.starovoitov@gmail.com

In the following bpf subprogram:
static int timer_cb(void *map, void *key, void *value)
{
    bpf_timer_set_callback(.., timer_cb);
}

the 'timer_cb' is a pointer to a function.
ld_imm64 insn is used to carry this pointer.
bpf_pseudo_func() returns true for such ld_imm64 insn.

Unlike bpf_for_each_map_elem() the bpf_timer_set_callback() is asynchronous.
Relax control flow check to allow such "recursion" that is seen as an infinite
loop by check_cfg(). The distinction between bpf_for_each_map_elem() the
bpf_timer_set_callback() is done in the follow up patch.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-8-alexei.starovoitov@gmail.com

BTF is required for 'struct bpf_timer' to be recognized inside map value.
The bpf timers are supported inside inner maps.
Remember 'struct btf *' in inner_map_meta to make it available
to the verifier in the sequence:

struct bpf_map *inner_map = bpf_map_lookup_elem(&outer_map, ...);
if (inner_map)
    timer = bpf_map_lookup_elem(&inner_map, ...);
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-7-alexei.starovoitov@gmail.com

bpf_timer_init() arguments are:
1. pointer to a timer (which is embedded in map element).
2. pointer to a map.
Make sure that pointer to a timer actually belongs to that map.

Use map_uid (which is unique id of inner map) to reject:
inner_map1 = bpf_map_lookup_elem(outer_map, key1)
inner_map2 = bpf_map_lookup_elem(outer_map, key2)
if (inner_map1 && inner_map2) {
    timer = bpf_map_lookup_elem(inner_map1);
    if (timer)
        // mismatch would have been allowed
        bpf_timer_init(timer, inner_map2);
}
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-6-alexei.starovoitov@gmail.com

Restrict bpf timers to array, hash (both preallocated and kmalloced), and
lru map types. The per-cpu maps with timers don't make sense, since 'struct
bpf_timer' is a part of map value. bpf timers in per-cpu maps would mean that
the number of timers depends on number of possible cpus and timers would not be
accessible from all cpus. lpm map support can be added in the future.
The timers in inner maps are supported.

The bpf_map_update/delete_elem() helpers and sys_bpf commands cancel and free
bpf_timer in a given map element.

Similar to 'struct bpf_spin_lock' BTF is required and it is used to validate
that map element indeed contains 'struct bpf_timer'.

Make check_and_init_map_value() init both bpf_spin_lock and bpf_timer when
map element data is reused in preallocated htab and lru maps.

Teach copy_map_value() to support both bpf_spin_lock and bpf_timer in a single
map element. There could be one of each, but not more than one. Due to 'one
bpf_timer in one element' restriction do not support timers in global data,
since global data is a map of single element, but from bpf program side it's
seen as many global variables and restriction of single global timer would be
odd. The sys_bpf map_freeze and sys_mmap syscalls are not allowed on maps with
timers, since user space could have corrupted mmap element and crashed the
kernel. The maps with timers cannot be readonly. Due to these restrictions
search for bpf_timer in datasec BTF in case it was placed in the global data to
report clear error.

The previous patch allowed 'struct bpf_timer' as a first field in a map
element only. Relax this restriction.

Refactor lru map to s/bpf_lru_push_free/htab_lru_push_free/ to cancel and free
the timer when lru map deletes an element as a part of it eviction algorithm.

Make sure that bpf program cannot access 'struct bpf_timer' via direct load/store.
The timer operation are done through helpers only.
This is similar to 'struct bpf_spin_lock'.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-5-alexei.starovoitov@gmail.com

Introduce 'struct bpf_timer { __u64 :64; __u64 :64; };' that can be embedded
in hash/array/lru maps as a regular field and helpers to operate on it:

// Initialize the timer.
// First 4 bits of 'flags' specify clockid.
// Only CLOCK_MONOTONIC, CLOCK_REALTIME, CLOCK_BOOTTIME are allowed.
long bpf_timer_init(struct bpf_timer *timer, struct bpf_map *map, int flags);

// Configure the timer to call 'callback_fn' static function.
long bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn);

// Arm the timer to expire 'nsec' nanoseconds from the current time.
long bpf_timer_start(struct bpf_timer *timer, u64 nsec, u64 flags);

// Cancel the timer and wait for callback_fn to finish if it was running.
long bpf_timer_cancel(struct bpf_timer *timer);

Here is how BPF program might look like:
struct map_elem {
    int counter;
    struct bpf_timer timer;
};

struct {
    __uint(type, BPF_MAP_TYPE_HASH);
    __uint(max_entries, 1000);
    __type(key, int);
    __type(value, struct map_elem);
} hmap SEC(".maps");

static int timer_cb(void *map, int *key, struct map_elem *val);
/* val points to particular map element that contains bpf_timer. */

SEC("fentry/bpf_fentry_test1")
int BPF_PROG(test1, int a)
{
    struct map_elem *val;
    int key = 0;

    val = bpf_map_lookup_elem(&hmap, &key);
    if (val) {
        bpf_timer_init(&val->timer, &hmap, CLOCK_REALTIME);
        bpf_timer_set_callback(&val->timer, timer_cb);
        bpf_timer_start(&val->timer, 1000 /* call timer_cb2 in 1 usec */, 0);
    }
}

This patch adds helper implementations that rely on hrtimers
to call bpf functions as timers expire.
The following patches add necessary safety checks.

Only programs with CAP_BPF are allowed to use bpf_timer.

The amount of timers used by the program is constrained by
the memcg recorded at map creation time.

The bpf_timer_init() helper needs explicit 'map' argument because inner maps
are dynamic and not known at load time. While the bpf_timer_set_callback() is
receiving hidden 'aux->prog' argument supplied by the verifier.

The prog pointer is needed to do refcnting of bpf program to make sure that
program doesn't get freed while the timer is armed. This approach relies on
"user refcnt" scheme used in prog_array that stores bpf programs for
bpf_tail_call. The bpf_timer_set_callback() will increment the prog refcnt which is
paired with bpf_timer_cancel() that will drop the prog refcnt. The
ops->map_release_uref is responsible for cancelling the timers and dropping
prog refcnt when user space reference to a map reaches zero.
This uref approach is done to make sure that Ctrl-C of user space process will
not leave timers running forever unless the user space explicitly pinned a map
that contained timers in bpffs.

bpf_timer_init() and bpf_timer_set_callback() will return -EPERM if map doesn't
have user references (is not held by open file descriptor from user space and
not pinned in bpffs).

The bpf_map_delete_elem() and bpf_map_update_elem() operations cancel
and free the timer if given map element had it allocated.
"bpftool map update" command can be used to cancel timers.

The 'struct bpf_timer' is explicitly __attribute__((aligned(8))) because
'__u64 :64' has 1 byte alignment of 8 byte padding.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-4-alexei.starovoitov@gmail.com

Move ____bpf_spin_lock/unlock into helpers to make it more clear
that quadruple underscore bpf_spin_lock/unlock are irqsave/restore variants.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-3-alexei.starovoitov@gmail.com

Currently bpf_prog_put() is called from the task context only.
With addition of bpf timers the timer related helpers will start calling
bpf_prog_put() from irq-saved region and in rare cases might drop
the refcnt to zero.
To address this case, first, convert bpf_prog_free_id() to be irq-save
(this is similar to bpf_map_free_id), and, second, defer non irq
appropriate calls into work queue.
For example:
bpf_audit_prog() is calling kmalloc and wake_up_interruptible,
bpf_prog_kallsyms_del_all()->bpf_ksym_del()->spin_unlock_bh().
They are not safe with irqs disabled.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-2-alexei.starovoitov@gmail.com

The variable buf is unused since commit 005edd16 ("selftests/bpf:
convert bpf tunnel test to BPF_ADJ_ROOM_MAC"). Remove it to fix the
following warning:

    test_tc_tunnel.c:531:7: warning: unused variable 'buf' [-Wunused-variable]

Fixes: 005edd16 ("selftests/bpf: convert bpf tunnel test to BPF_ADJ_ROOM_MAC")
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210713102719.8890-1-tklauser@distanz.ch

In bpf_patch_insn_data(), we first use the bpf_patch_insn_single() to
insert new instructions, then use adjust_insn_aux_data() to adjust
insn_aux_data. If the old env->prog have no enough room for new inserted
instructions, we use bpf_prog_realloc to construct new_prog and free the
old env->prog.

There have two errors here. First, if adjust_insn_aux_data() return
ENOMEM, we should free the new_prog. Second, if adjust_insn_aux_data()
return ENOMEM, bpf_patch_insn_data() will return NULL, and env->prog has
been freed in bpf_prog_realloc, but we will use it in bpf_check().

So in this patch, we make the adjust_insn_aux_data() never fails. In
bpf_patch_insn_data(), we first pre-malloc memory for the new
insn_aux_data, then call bpf_patch_insn_single() to insert new
instructions, at last call adjust_insn_aux_data() to adjust
insn_aux_data.

Fixes: 8041902d ("bpf: adjust insn_aux_data when patching insns")
Signed-off-by: He Fengqing <hefengqing@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210714101815.164322-1-hefengqing@huawei.com

Fix s/BPF_MAP_TYPE_REUSEPORT_ARRAY/BPF_MAP_TYPE_REUSEPORT_SOCKARRAY/ typo
in bpf.h.

Fixes: 2dbb9b9e ("bpf: Introduce BPF_PROG_TYPE_SK_REUSEPORT")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210714124317.67526-1-kuniyu@amazon.co.jp

Commit 47316f4a missed updating tools/.../bpf.h.
Sync it.

Fixes: 47316f4a ("bpf: Support input xdp_md context in BPF_PROG_TEST_RUN")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

When loading a BPF program with a pinned map, the loader checks whether
the pinned map can be reused, i.e. their properties match. To derive
such of the pinned map, the loader invokes BPF_OBJ_GET_INFO_BY_FD and
then does the comparison.

Unfortunately, on < 4.12 kernels the BPF_OBJ_GET_INFO_BY_FD is not
available, so loading the program fails with the following error:

	libbpf: failed to get map info for map FD 5: Invalid argument
	libbpf: couldn't reuse pinned map at
		'/sys/fs/bpf/tc/globals/cilium_call_policy': parameter
		mismatch"
	libbpf: map 'cilium_call_policy': error reusing pinned map
	libbpf: map 'cilium_call_policy': failed to create:
		Invalid argument(-22)
	libbpf: failed to load object 'bpf_overlay.o'

To fix this, fallback to derivation of the map properties via
/proc/$PID/fdinfo/$MAP_FD if BPF_OBJ_GET_INFO_BY_FD fails with EINVAL,
which can be used as an indicator that the kernel doesn't support
the latter.
Signed-off-by: Martynas Pumputis <m@lambda.lt>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210712125552.58705-1-m@lambda.lt

Experience from production shows queue size of 192 is too small, as
this caused packet drops during cpumap-enqueue on RX-CPU.  This can be
diagnosed with xdp_monitor sample program.

This bpftrace program was used to diagnose the problem in more detail:

 bpftrace -e '
  tracepoint:xdp:xdp_cpumap_kthread { @deq_bulk = lhist(args->processed,0,10,1); @drop_net = lhist(args->drops,0,10,1) }
  tracepoint:xdp:xdp_cpumap_enqueue { @enq_bulk = lhist(args->processed,0,10,1); @enq_drops = lhist(args->drops,0,10,1); }'

Watch out for the @enq_drops counter. The @drop_net counter can happen
when netstack gets invalid packets, so don't despair it can be
natural, and that counter will likely disappear in newer kernels as it
was a source of confusion (look at netstat info for reason of the
netstack @drop_net counters).

The production system was configured with CPU power-saving C6 state.
Learn more in this blogpost[1].

And wakeup latency in usec for the states are:

 # grep -H . /sys/devices/system/cpu/cpu0/cpuidle/*/latency
 /sys/devices/system/cpu/cpu0/cpuidle/state0/latency:0
 /sys/devices/system/cpu/cpu0/cpuidle/state1/latency:2
 /sys/devices/system/cpu/cpu0/cpuidle/state2/latency:10
 /sys/devices/system/cpu/cpu0/cpuidle/state3/latency:133

Deepest state take 133 usec to wakeup from (133/10^6). The link speed
is 25Gbit/s ((25*10^9/8) in bytes/sec). How many bytes can arrive with
in 133 usec at this speed: (25*10^9/8)*(133/10^6) = 415625 bytes. With
MTU size packets this is 275 packets, and with minimum Ethernet (incl
intergap overhead) 84 bytes it is 4948 packets. Clearly default queue
size is too small.

Setting default cpumap queue to 2048 as worst-case (small packet) at
10Gbit/s is 1979 packets with 133 usec wakeup time, +64 packet before
kthread wakeup call (due to xdp_do_flush) worst-case 2043 packets.

Thus, if a packet burst on RX-CPU will enqueue packets to a remote
cpumap CPU that is in deep-sleep state it can overrun the cpumap queue.

The production system was also configured to avoid deep-sleep via:
 tuned-adm profile network-latency

[1] https://jeremyeder.com/2013/08/30/oh-did-you-expect-the-cpu/Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/162523477604.786243.13372630844944530891.stgit@firesoul

Kumar Kartikeya says:

====================

This small series makes some improvements to generic XDP mode and brings it
closer to native XDP. Patch 1 splits out generic XDP processing into reusable
parts, patch 2 adds pointer friendly wrappers for bitops (not have to cast back
and forth the address of local pointer to unsigned long *), patch 3 implements
generic cpumap support (details in commit) and patch 4 allows devmap bpf prog
execution before generic_xdp_tx is called.

Patch 5 just updates a couple of selftests to adapt to changes in behavior (in
that specifying devmap/cpumap prog fd in generic mode is now allowed).

Changelog:
----------
v5 -> v6
v5: https://lore.kernel.org/bpf/20210701002759.381983-1-memxor@gmail.com
 * Put rcpu->prog check before RCU-bh section to avoid do_softirq (Jesper)

v4 -> v5
v4: https://lore.kernel.org/bpf/20210628114746.129669-1-memxor@gmail.com
 * Add comments and examples for new bitops macros (Alexei)

v3 -> v4
v3: https://lore.kernel.org/bpf/20210622202835.1151230-1-memxor@gmail.com
 * Add detach now that attach of XDP program succeeds (Toke)
 * Clean up the test to use new ASSERT macros

v2 -> v3
v2: https://lore.kernel.org/bpf/20210622195527.1110497-1-memxor@gmail.com
 * list_for_each_entry -> list_for_each_entry_safe (due to deletion of skb)

v1 -> v2
v1: https://lore.kernel.org/bpf/20210620233200.855534-1-memxor@gmail.com
 * Move __ptr_{set,clear,test}_bit to bitops.h (Toke)
   Also changed argument order to match the bit op they wrap.
 * Remove map value size checking functions for cpumap/devmap (Toke)
 * Rework prog run for skb in cpu_map_kthread_run (Toke)
 * Set skb->dev to dst->dev after devmap prog has run
 * Don't set xdp rxq that will be overwritten in cpumap prog run
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Support for cpumap and devmap entry progs in previous commits means the
test needs to be updated for the new semantics. Also take this
opportunity to convert it from CHECK macros to the new ASSERT macros.

Since xdp_cpumap_attach has no subtest, put the sole test inside the
test_xdp_cpumap_attach function.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210702111825.491065-6-memxor@gmail.com

This lifts the restriction on running devmap BPF progs in generic
redirect mode. To match native XDP behavior, it is invoked right before
generic_xdp_tx is called, and only supports XDP_PASS/XDP_ABORTED/
XDP_DROP actions.

We also return 0 even if devmap program drops the packet, as
semantically redirect has already succeeded and the devmap prog is the
last point before TX of the packet to device where it can deliver a
verdict on the packet.

This also means it must take care of freeing the skb, as
xdp_do_generic_redirect callers only do that in case an error is
returned.

Since devmap entry prog is supported, remove the check in
generic_xdp_install entirely.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210702111825.491065-5-memxor@gmail.com

This change implements CPUMAP redirect support for generic XDP programs.
The idea is to reuse the cpu map entry's queue that is used to push
native xdp frames for redirecting skb to a different CPU. This will
match native XDP behavior (in that RPS is invoked again for packet
reinjected into networking stack).

To be able to determine whether the incoming skb is from the driver or
cpumap, we reuse skb->redirected bit that skips generic XDP processing
when it is set. To always make use of this, CONFIG_NET_REDIRECT guard on
it has been lifted and it is always available.

>From the redirect side, we add the skb to ptr_ring with its lowest bit
set to 1.  This should be safe as skb is not 1-byte aligned. This allows
kthread to discern between xdp_frames and sk_buff. On consumption of the
ptr_ring item, the lowest bit is unset.

In the end, the skb is simply added to the list that kthread is anyway
going to maintain for xdp_frames converted to skb, and then received
again by using netif_receive_skb_list.

Bulking optimization for generic cpumap is left as an exercise for a
future patch for now.

Since cpumap entry progs are now supported, also remove check in
generic_xdp_install for the cpumap.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20210702111825.491065-4-memxor@gmail.com

cpumap needs to set, clear, and test the lowest bit in skb pointer in
various places. To make these checks less noisy, add pointer friendly
bitop macros that also do some typechecking to sanitize the argument.

These wrap the non-atomic bitops __set_bit, __clear_bit, and test_bit
but for pointer arguments. Pointer's address has to be passed in and it
is treated as an unsigned long *, since width and representation of
pointer and unsigned long match on targets Linux supports. They are
prefixed with double underscore to indicate lack of atomicity.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210702111825.491065-3-memxor@gmail.com

This helper can later be utilized in code that runs cpumap and devmap
programs in generic redirect mode and adjust skb based on changes made
to xdp_buff.

When returning XDP_REDIRECT/XDP_TX, it invokes __skb_push, so whenever a
generic redirect path invokes devmap/cpumap prog if set, it must
__skb_pull again as we expect mac header to be pulled.

It also drops the skb_reset_mac_len call after do_xdp_generic, as the
mac_header and network_header are advanced by the same offset, so the
difference (mac_len) remains constant.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210702111825.491065-2-memxor@gmail.com

Zvi Effron says:

====================

This patchset adds support for passing an xdp_md via ctx_in/ctx_out in
bpf_attr for BPF_PROG_TEST_RUN of XDP programs.

Patch 1 adds a function to validate XDP meta data lengths.

Patch 2 adds initial support for passing XDP meta data in addition to
packet data.

Patch 3 adds support for also specifying the ingress interface and
rx queue.

Patch 4 adds selftests to ensure functionality is correct.

Changelog:
----------
v7->v8
v7: https://lore.kernel.org/bpf/20210624211304.90807-1-zeffron@riotgames.com/

 * Fix too long comment line in patch 3

v6->v7
v6: https://lore.kernel.org/bpf/20210617232904.1899-1-zeffron@riotgames.com/

 * Add Yonghong Song's Acked-by to commit message in patch 1
 * Add Yonghong Song's Acked-by to commit message in patch 2
 * Extracted the post-update of the xdp_md context into a function (again)
 * Validate that the rx queue was registered with XDP info
 * Decrement the reference count on a found netdevice on failure to find
  a valid rx queue
 * Decrement the reference count on a found netdevice after the XDP
  program is run
 * Drop Yonghong Song's Acked-By for patch 3 because of patch changes
 * Improve a comment in the selftests
 * Drop Yonghong Song's Acked-By for patch 4 because of patch changes

v5->v6
v5: https://lore.kernel.org/bpf/20210616224712.3243-1-zeffron@riotgames.com/

 * Correct commit messages in patches 1 and 3
 * Add Acked-by to commit message in patch 4
 * Use gotos instead of returns to correctly free resources in
  bpf_prog_test_run_xdp
 * Rename xdp_metalen_valid to xdp_metalen_invalid
 * Improve the function signature for xdp_metalen_invalid
 * Merged declaration of ingress_ifindex and rx_queue_index into one line

v4->v5
v4: https://lore.kernel.org/bpf/20210604220235.6758-1-zeffron@riotgames.com/

 * Add new patch to introduce xdp_metalen_valid inline function to avoid
  duplicated code from net/core/filter.c
 * Correct size of bad_ctx in selftests
 * Make all declarations reverse Christmas tree
 * Move data check from xdp_convert_md_to_buff to bpf_prog_test_run_xdp
 * Merge xdp_convert_buff_to_md into bpf_prog_test_run_xdp
 * Fix line too long
 * Extracted common checks in selftests to a helper function
 * Removed redundant assignment in selftests
 * Reordered test cases in selftests
 * Check data against 0 instead of data_meta in selftests
 * Made selftests use EINVAL instead of hardcoded 22
 * Dropped "_" from XDP function name
 * Changed casts in XDP program from unsigned long to long
 * Added a comment explaining the use of the loopback interface in selftests
 * Change parameter order in xdp_convert_md_to_buff to be input first
 * Assigned xdp->ingress_ifindex and xdp->rx_queue_index to local variables in
  xdp_convert_md_to_buff
 * Made use of "meta data" versus "metadata" consistent in comments and commit
  messages

v3->v4
v3: https://lore.kernel.org/bpf/20210602190815.8096-1-zeffron@riotgames.com/

 * Clean up nits
 * Validate xdp_md->data_end in bpf_prog_test_run_xdp
 * Remove intermediate metalen variables

v2 -> v3
v2: https://lore.kernel.org/bpf/20210527201341.7128-1-zeffron@riotgames.com/

 * Check errno first in selftests
 * Use DECLARE_LIBBPF_OPTS
 * Rename tattr to opts in selftests
 * Remove extra new line
 * Rename convert_xdpmd_to_xdpb to xdp_convert_md_to_buff
 * Rename convert_xdpb_to_xdpmd to xdp_convert_buff_to_md
 * Move declaration of device and rxqueue in xdp_convert_md_to_buff to
  patch 2
 * Reorder the kfree calls in bpf_prog_test_run_xdp

v1 -> v2
v1: https://lore.kernel.org/bpf/20210524220555.251473-1-zeffron@riotgames.com

 * Fix null pointer dereference with no context
 * Use the BPF skeleton and replace CHECK with ASSERT macros
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>