If there are pending rcu callback, free_mem_alloc() will use
rcu_barrier_tasks_trace() and rcu_barrier() to wait for the pending
__free_rcu_tasks_trace() and __free_rcu() callback.

If rcu_trace_implies_rcu_gp() is true, there will be no pending
__free_rcu(), so it will be OK to skip rcu_barrier() as well.
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20221209010947.3130477-3-houtao@huaweicloud.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

When there are batched freeing operations on a specific CPU, part of
the freed elements ((high_watermark - lower_watermark) / 2 + 1) will be
indirectly moved into waiting_for_gp list through free_by_rcu list.
After call_rcu_in_progress becomes false again, the remaining elements
in free_by_rcu list will be moved to waiting_for_gp list by the next
invocation of free_bulk(). However if the expiration of RCU tasks trace
grace period is relatively slow, none element in free_by_rcu list will
be moved.

So instead of invoking __alloc_percpu_gfp() or kmalloc_node() to
allocate a new object, in alloc_bulk() just check whether or not there is
freed element in free_by_rcu list and reuse it if available.
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20221209010947.3130477-2-houtao@huaweicloud.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Bpftool has new extra libbpf_det_bind probing map we need to exclude.
Also skip trying to load netdevsim modules if it's already loaded (builtin).

v2:
- drop iproute2->bpftool changes (Toke)
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221206232739.2504890-1-sdf@google.com

insn->imm for kfunc is the relative address of __bpf_call_base,
instead of __bpf_base_call, Fix the comment error.
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Link: https://lore.kernel.org/r/20221208013724.257848-1-yangjihong1@huawei.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

In BPF all global functions, and BPF helpers return a 64-bit
value. For kfunc calls, this is not the case, and they can return
e.g. 32-bit values.

The return register R0 for kfuncs calls can therefore be marked as
subreg_def != DEF_NOT_SUBREG. In general, if a register is marked with
subreg_def != DEF_NOT_SUBREG, some archs (where bpf_jit_needs_zext()
returns true) require the verifier to insert explicit zero-extension
instructions.

For kfuncs calls, however, the caller should do sign/zero extension
for return values. In other words, the compiler is responsible to
insert proper instructions, not the verifier.

An example, provided by Yonghong Song:

$ cat t.c
extern unsigned foo(void);
unsigned bar1(void) {
     return foo();
}
unsigned bar2(void) {
     if (foo()) return 10; else return 20;
}

$ clang -target bpf -mcpu=v3 -O2 -c t.c && llvm-objdump -d t.o
t.o:    file format elf64-bpf

Disassembly of section .text:

0000000000000000 <bar1>:
	0:       85 10 00 00 ff ff ff ff call -0x1
	1:       95 00 00 00 00 00 00 00 exit

0000000000000010 <bar2>:
	2:       85 10 00 00 ff ff ff ff call -0x1
	3:       bc 01 00 00 00 00 00 00 w1 = w0
	4:       b4 00 00 00 14 00 00 00 w0 = 0x14
	5:       16 01 01 00 00 00 00 00 if w1 == 0x0 goto +0x1 <LBB1_2>
	6:       b4 00 00 00 0a 00 00 00 w0 = 0xa

0000000000000038 <LBB1_2>:
	7:       95 00 00 00 00 00 00 00 exit

If the return value of 'foo()' is used in the BPF program, the proper
zero-extension will be done.

Currently, the verifier correctly marks, say, a 32-bit return value as
subreg_def != DEF_NOT_SUBREG, but will fail performing the actual
zero-extension, due to a verifier bug in
opt_subreg_zext_lo32_rnd_hi32(). load_reg is not properly set to R0,
and the following path will be taken:

		if (WARN_ON(load_reg == -1)) {
			verbose(env, "verifier bug. zext_dst is set, but no reg is defined\n");
			return -EFAULT;
		}

A longer discussion from v1 can be found in the link below.

Correct the verifier by avoiding doing explicit zero-extension of R0
for kfunc calls. Note that R0 will still be marked as a sub-register
for return values smaller than 64-bit.

Fixes: 83a28819 ("bpf: Account for BPF_FETCH in insn_has_def32()")
Link: https://lore.kernel.org/bpf/20221202103620.1915679-1-bjorn@kernel.org/Suggested-by: Yonghong Song <yhs@meta.com>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221207103540.396496-1-bjorn@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

David Vernet says:

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

A series of recent patch sets introduced kfuncs that allowed struct
task_struct and struct cgroup objects to be used as kptrs. These were
introduced in [0], [1], and [2].

[0]: https://lore.kernel.org/lkml/20221120051004.3605026-1-void@manifault.com/
[1]: https://lore.kernel.org/lkml/20221122145300.251210-2-void@manifault.com/T/
[2]: https://lore.kernel.org/lkml/20221122055458.173143-1-void@manifault.com/

These are "core" kfuncs, in that they may be used by a wide variety of
possible BPF tracepoint or struct_ops programs, and are defined in
kernel/bpf/helpers.c. Even though as kfuncs they have no ABI stability
guarantees, they should still be properly documented. This patch set
adds that documentation.

Some other kfuncs were added recently as well, such as
bpf_rcu_read_lock() and bpf_rcu_read_unlock(). Those could and should be
added to this "Core kfuncs" section as well in subsequent patch sets.

Note that this patch set does not contain documentation for
bpf_task_acquire_not_zero(), or bpf_task_kptr_get(). As discussed in
[3], those kfuncs currently always return NULL pending resolution on how
to properly protect their arguments using RCU.

[3]: https://lore.kernel.org/all/20221206210538.597606-1-void@manifault.com/
---
Changelog:
v2 -> v3:
- Don't document bpf_task_kptr_get(), and instead provide a more
  substantive example for bpf_cgroup_kptr_get().
- Further clarify expected behavior of bpf_task_from_pid() in comments
  (Alexei)

v1 -> v2:
- Expand comment to specify that a map holds a reference to a task kptr
  if we don't end up releasing it (Alexei)
- Just read task->pid instead of using a probed read (Alexei)
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

bpf_cgroup_acquire(), bpf_cgroup_release(), bpf_cgroup_kptr_get(), and
bpf_cgroup_ancestor(), are kfuncs that were recently added to
kernel/bpf/helpers.c. These are "core" kfuncs in that they're available
for use in any tracepoint or struct_ops BPF program. Though they have no
ABI stability guarantees, we should still document them. This patch adds
a struct cgroup * subsection to the Core kfuncs section which describes
each of these kfuncs.
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221207204911.873646-3-void@manifault.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

bpf_task_acquire(), bpf_task_release(), and bpf_task_from_pid() are
kfuncs that were recently added to kernel/bpf/helpers.c. These are
"core" kfuncs in that they're available for use for any tracepoint or
struct_ops BPF program. Though they have no ABI stability guarantees, we
should still document them. This patch adds a new Core kfuncs section to
the BPF kfuncs doc, and adds entries for all of these task kfuncs.

Note that bpf_task_kptr_get() is not documented, as it still returns
NULL while we're working to resolve how it can use RCU to ensure struct
task_struct * lifetime.
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221207204911.873646-2-void@manifault.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Convert big chunks of dynptr and map_kptr subtests to use generic
verification_tester. They are switched from using manually maintained
tables of test cases, specifying program name and expected error
verifier message, to btf_decl_tag-based annotations directly on
corresponding BPF programs: __failure to specify that BPF program is
expected to fail verification, and __msg() to specify expected log
message.
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221207201648.2990661-2-andrii@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

It's become a common pattern to have a collection of small BPF programs
in one BPF object file, each representing one test case. On user-space
side of such tests we maintain a table of program names and expected
failure or success, along with optional expected verifier log message.

This works, but each set of tests reimplement this mundane code over and
over again, which is a waste of time for anyone trying to add a new set
of tests. Furthermore, it's quite error prone as it's way too easy to miss
some entries in these manually maintained test tables (as evidences by
dynptr_fail tests, in which ringbuf_release_uninit_dynptr subtest was
accidentally missed; this is fixed in next patch).

So this patch implements generic test_loader, which accepts skeleton
name and handles the rest of details: opens and loads BPF object file,
making sure each program is tested in isolation. Optionally each test
case can specify expected BPF verifier log message. In case of failure,
tester makes sure to report verifier log, but it also reports verifier
log in verbose mode unconditionally.

Now, the interesting deviation from existing custom implementations is
the use of btf_decl_tag attribute to specify expected-to-fail vs
expected-to-succeed markers and, optionally, expected log message
directly next to BPF program source code, eliminating the need to
manually create and update table of tests.

We define few macros wrapping btf_decl_tag with a convention that all
values of btf_decl_tag start with "comment:" prefix, and then utilizing
a very simple "just_some_text_tag" or "some_key_name=<value>" pattern to
define things like expected success/failure, expected verifier message,
extra verifier log level (if necessary). This approach is demonstrated
by next patch in which two existing sets of failure tests are converted.

Tester supports both expected-to-fail and expected-to-succeed programs,
though this patch set didn't convert any existing expected-to-succeed
programs yet, as existing tests couple BPF program loading with their
further execution through attach or test_prog_run. One way to allow
testing scenarios like this would be ability to specify custom callback,
executed for each successfully loaded BPF program. This is left for
follow up patches, after some more analysis of existing test cases.

This test_loader is, hopefully, a start of a test_verifier-like runner,
but integrated into test_progs infrastructure. It will allow much better
"user experience" of defining low-level verification tests that can take
advantage of all the libbpf-provided nicety features on BPF side: global
variables, declarative maps, etc.  All while having a choice of defining
it in C or as BPF assembly (through __attribute__((naked)) functions and
using embedded asm), depending on what makes most sense in each
particular case. This will be explored in follow up patches as well.
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20221207201648.2990661-1-andrii@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Number of total instructions in BPF program (including subprogs) can and
is accessed from env->prog->len. visit_func_call_insn() doesn't do any
checks against insn_cnt anymore, relying on push_insn() to do this check
internally. So remove unnecessary insn_cnt input argument from
visit_func_call_insn() and visit_insn() functions.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221207195534.2866030-1-andrii@kernel.org

Merge commit 5b481aca ("bpf: do not rely on ALLOW_ERROR_INJECTION for fmod_ret")
from hid tree into bpf-next.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

The current way of expressing that a non-bpf kernel component is willing
to accept that bpf programs can be attached to it and that they can change
the return value is to abuse ALLOW_ERROR_INJECTION.
This is debated in the link below, and the result is that it is not a
reasonable thing to do.

Reuse the kfunc declaration structure to also tag the kernel functions
we want to be fmodret. This way we can control from any subsystem which
functions are being modified by bpf without touching the verifier.

Link: https://lore.kernel.org/all/20221121104403.1545f9b5@gandalf.local.home/Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20221206145936.922196-2-benjamin.tissoires@redhat.com

There is no need to include <linux/rculist.h> here.

Prefer the less invasive <linux/types.h> which is needed for 'hlist_head'.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/88d6a1d88764cca328610854f890a9ca1f4b029e.1670086246.git.christophe.jaillet@wanadoo.frSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Andrii Nakryiko says:

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

Disentangle prune and jump points in BPF verifier code. They are conceptually
independent but currently coupled together. This small patch set refactors
related code and make it possible to have some instruction marked as pruning
or jump point independently.

Besides just conceptual cleanliness, this allows to remove unnecessary jump
points (saving a tiny bit of performance and memory usage, potentially), and
even more importantly it allows for clean extension of special pruning points,
similarly to how it's done for BPF_FUNC_timer_set_callback. This will be used
by future patches implementing open-coded BPF iterators.

v1->v2:
  - clarified path #3 commit message and a comment in the code (John);
  - added back mark_jmp_point() to right after subprog call to record
    non-linear implicit jump from BPF_EXIT to right after CALL <subprog>.
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Don't mark some instructions as jump points when there are actually no
jumps and instructions are just processed sequentially. Such case is
handled naturally by precision backtracking logic without the need to
update jump history. See get_prev_insn_idx(). It goes back linearly by
one instruction, unless current top of jmp_history is pointing to
current instruction. In such case we use `st->jmp_history[cnt - 1].prev_idx`
to find instruction from which we jumped to the current instruction
non-linearly.

Also remove both jump and prune point marking for instruction right
after unconditional jumps, as program flow can get to the instruction
right after unconditional jump instruction only if there is a jump to
that instruction from somewhere else in the program. In such case we'll
mark such instruction as prune/jump point because it's a destination of
a jump.

This change has no changes in terms of number of instructions or states
processes across Cilium and selftests programs.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20221206233345.438540-4-andrii@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Jump history updating and state equivalence checks are conceptually
independent, so move push_jmp_history() out of is_state_visited(). Also
make a decision whether to perform state equivalence checks or not one
layer higher in do_check(), keeping is_state_visited() unconditionally
performing state checks.

push_jmp_history() should be performed after state checks. There is just
one small non-uniformity. When is_state_visited() finds already
validated equivalent state, it propagates precision marks to current
state's parent chain. For this to work correctly, jump history has to be
updated, so is_state_visited() is doing that internally.

But if no equivalent verified state is found, jump history has to be
updated in a newly cloned child state, so is_jmp_point()
+ push_jmp_history() is performed after is_state_visited() exited with
zero result, which means "proceed with validation".

This change has no functional changes. It's not strictly necessary, but
feels right to decouple these two processes.
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20221206233345.438540-3-andrii@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

BPF verifier marks some instructions as prune points. Currently these
prune points serve two purposes.

It's a point where verifier tries to find previously verified state and
check current state's equivalence to short circuit verification for
current code path.

But also currently it's a point where jump history, used for precision
backtracking, is updated. This is done so that non-linear flow of
execution could be properly backtracked.

Such coupling is coincidental and unnecessary. Some prune points are not
part of some non-linear jump path, so don't need update of jump history.
On the other hand, not all instructions which have to be recorded in
jump history necessarily are good prune points.

This patch splits prune and jump points into independent flags.
Currently all prune points are marked as jump points to minimize amount
of changes in this patch, but next patch will perform some optimization
of prune vs jmp point placement.

No functional changes are intended.
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20221206233345.438540-2-andrii@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

btf->struct_meta_tab is populated by btf_parse_struct_metas in btf.c.
There, a BTF record is created for any type containing a spin_lock or
any next-gen datastructure node/head.

Currently, for non-MAP_VALUE types, reg_btf_record will only search for
a record using struct_meta_tab if the reg->type exactly matches
(PTR_TO_BTF_ID | MEM_ALLOC). This exact match is too strict: an
"allocated obj" type - returned from bpf_obj_new - might pick up other
flags while working its way through the program.

Loosen the check to be exact for base_type and just use MEM_ALLOC mask
for type_flag.

This patch is marked Fixes as the original intent of reg_btf_record was
unlikely to have been to fail finding btf_record for valid alloc obj
types with additional flags, some of which (e.g. PTR_UNTRUSTED)
are valid register type states for alloc obj independent of this series.
However, I didn't find a specific broken repro case outside of this
series' added functionality, so it's possible that nothing was
triggering this logic error before.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Fixes: 4e814da0 ("bpf: Allow locking bpf_spin_lock in allocated objects")
Link: https://lore.kernel.org/r/20221206231000.3180914-2-davemarchevsky@fb.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

A series of prior patches added some kfuncs that allow struct
task_struct * objects to be used as kptrs. These kfuncs leveraged the
'refcount_t rcu_users' field of the task for performing refcounting.
This field was used instead of 'refcount_t usage', as we wanted to
leverage the safety provided by RCU for ensuring a task's lifetime.

A struct task_struct is refcounted by two different refcount_t fields:

1. p->usage:     The "true" refcount field which task lifetime. The
		 task is freed as soon as this refcount drops to 0.

2. p->rcu_users: An "RCU users" refcount field which is statically
		 initialized to 2, and is co-located in a union with
		 a struct rcu_head field (p->rcu). p->rcu_users
		 essentially encapsulates a single p->usage
		 refcount, and when p->rcu_users goes to 0, an RCU
		 callback is scheduled on the struct rcu_head which
		 decrements the p->usage refcount.

Our logic was that by using p->rcu_users, we would be able to use RCU to
safely issue refcount_inc_not_zero() a task's rcu_users field to
determine if a task could still be acquired, or was exiting.
Unfortunately, this does not work due to p->rcu_users and p->rcu sharing
a union. When p->rcu_users goes to 0, an RCU callback is scheduled to
drop a single p->usage refcount, and because the fields share a union,
the refcount immediately becomes nonzero again after the callback is
scheduled.

If we were to split the fields out of the union, this wouldn't be a
problem. Doing so should also be rather non-controversial, as there are
a number of places in struct task_struct that have padding which we
could use to avoid growing the structure by splitting up the fields.

For now, so as to fix the kfuncs to be correct, this patch instead
updates bpf_task_acquire() and bpf_task_release() to use the p->usage
field for refcounting via the get_task_struct() and put_task_struct()
functions. Because we can no longer rely on RCU, the change also guts
the bpf_task_acquire_not_zero() and bpf_task_kptr_get() functions
pending a resolution on the above problem.

In addition, the task fixes the kfunc and rcu_read_lock selftests to
expect this new behavior.

Fixes: 90660309 ("bpf: Add kfuncs for storing struct task_struct * as a kptr")
Fixes: fca1aa75 ("bpf: Handle MEM_RCU type properly")
Reported-by: Matus Jokay <matus.jokay@stuba.sk>
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221206210538.597606-1-void@manifault.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Daan De Meyer says:

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

This patch series fixes a few issues I've found while integrating the
bpf selftests into systemd's mkosi development environment.
====================
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

CONFIG_TEST_BPF can only be a module, so let's indicate it as such in
the selftests config.
Signed-off-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221205131618.1524337-4-daan.j.demeyer@gmail.com

"=n" is not valid kconfig syntax. Use "is not set" instead to indicate
the option should be disabled.
Signed-off-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221205131618.1524337-3-daan.j.demeyer@gmail.com

When installing the selftests using
"make -C tools/testing/selftests install", we need to make sure
all the required files to run the selftests are installed. Let's
make sure this is the case.
Signed-off-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221205131618.1524337-2-daan.j.demeyer@gmail.com

Parse USDT arguments like "8@(%rsp)" on x86. These are emmited by
SystemTap. The argument syntax is similar to the existing "memory
dereference case" but the offset left out as it's zero (i.e. read
the value from the address in the register). We treat it the same
as the the "memory dereference case", but set the offset to 0.

I've tested that this fixes the "unrecognized arg #N spec: 8@(%rsp).."
error I've run into when attaching to a probe with such an argument.
Attaching and reading the correct argument values works.

Something similar might be needed for the other supported
architectures.

  [0] Closes: https://github.com/libbpf/libbpf/issues/559Signed-off-by: Timo Hunziker <timo.hunziker@gmx.ch>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221203123746.2160-1-timo.hunziker@eclipso.ch

It is useful to use vmlinux.h in the xfrm_info test like other kfunc
tests do.  In particular, it is common for kfunc bpf prog that requires
to use other core kernel structures in vmlinux.h

Although vmlinux.h is preferred, it needs a ___local flavor of
struct bpf_xfrm_info in order to build the bpf selftests
when CONFIG_XFRM_INTERFACE=[m|n].

Cc: Eyal Birger <eyal.birger@gmail.com>
Fixes: 90a3a05e ("selftests/bpf: add xfrm_info tests")
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20221206193554.1059757-1-martin.lau@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

strdup() allocates memory for path. We need to release the memory in the
following error path. Add free() to avoid memory leak.

Fixes: 8f184732 ("bpftool: Switch to libbpf's hashmap for pinned paths of BPF objects")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221206071906.806384-1-linmq006@gmail.com

For BPF_PSEUDO_FUNC instruction, verifier will refill imm with
correct addresses of bpf_calls and then run last pass of JIT.
Since the emit_imm of RV64 is variable-length, which will emit
appropriate length instructions accorroding to the imm, it may
broke ctx->offset, and lead to unpredictable problem, such as
inaccurate jump. So let's fix it with fixed-length instructions.

Fixes: 69c087ba ("bpf: Add bpf_for_each_map_elem() helper")
Suggested-by: Björn Töpel <bjorn@rivosinc.com>
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Björn Töpel <bjorn@kernel.org>
Acked-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/bpf/20221206091410.1584784-1-pulehui@huaweicloud.com

Eyal Birger says:

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

This patch series adds xfrm metadata helpers using the unstable kfunc
call interface for the TC-BPF hooks.

This allows steering traffic towards different IPsec connections based
on logic implemented in bpf programs.

The helpers are integrated into the xfrm_interface module. For this
purpose the main functionality of this module is moved to
xfrm_interface_core.c.
---

changes in v6: fix sparse warning in patch 2
changes in v5:
  - avoid cleanup of percpu dsts as detailed in patch 2
changes in v3:
  - tag bpf-next tree instead of ipsec-next
  - add IFLA_XFRM_COLLECT_METADATA sync patch
====================
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

Test the xfrm_info kfunc helpers.

The test setup creates three name spaces - NS0, NS1, NS2.

XFRM tunnels are setup between NS0 and the two other NSs.

The kfunc helpers are used to steer traffic from NS0 to the other
NSs based on a userspace populated bpf global variable and validate
that the return traffic had arrived from the desired NS.
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Link: https://lore.kernel.org/r/20221203084659.1837829-5-eyal.birger@gmail.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

Needed for XFRM metadata tests.
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Link: https://lore.kernel.org/r/20221203084659.1837829-4-eyal.birger@gmail.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

This change adds xfrm metadata helpers using the unstable kfunc call
interface for the TC-BPF hooks. This allows steering traffic towards
different IPsec connections based on logic implemented in bpf programs.

This object is built based on the availability of BTF debug info.

When setting the xfrm metadata, percpu metadata dsts are used in order
to avoid allocating a metadata dst per packet.

In order to guarantee safe module unload, the percpu dsts are allocated
on first use and never freed. The percpu pointer is stored in
net/core/filter.c so that it can be reused on module reload.

The metadata percpu dsts take ownership of the original skb dsts so
that they may be used as part of the xfrm transmission logic - e.g.
for MTU calculations.
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Link: https://lore.kernel.org/r/20221203084659.1837829-3-eyal.birger@gmail.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

This change allows adding additional files to the xfrm_interface module.
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Link: https://lore.kernel.org/r/20221203084659.1837829-2-eyal.birger@gmail.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

Both tolower and toupper are built in c functions, we should not
redefine them as this can result in a build error.

Fixes the following errors:
progs/bpf_iter_ksym.c:10:20: error: conflicting types for built-in function 'tolower'; expected 'int(int)' [-Werror=builtin-declaration-mismatch]
   10 | static inline char tolower(char c)
      |                    ^~~~~~~
progs/bpf_iter_ksym.c:5:1: note: 'tolower' is declared in header '<ctype.h>'
    4 | #include <bpf/bpf_helpers.h>
  +++ |+#include <ctype.h>
    5 |
progs/bpf_iter_ksym.c:17:20: error: conflicting types for built-in function 'toupper'; expected 'int(int)' [-Werror=builtin-declaration-mismatch]
   17 | static inline char toupper(char c)
      |                    ^~~~~~~
progs/bpf_iter_ksym.c:17:20: note: 'toupper' is declared in header '<ctype.h>'

See background on this sort of issue:
https://stackoverflow.com/a/20582607
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=12213

(C99, 7.1.3p1) "All identifiers with external linkage in any of the
following subclauses (including the future library directions) are
always reserved for use as identifiers with external linkage."

This is documented behavior in GCC:
https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-std-2Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20221203010847.2191265-1-james.hilliard1@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

sock_map_free() calls release_sock(sk) without owning a reference
on the socket. This can cause use-after-free as syzbot found [1]

Jakub Sitnicki already took care of a similar issue
in sock_hash_free() in commit 75e68e5b ("bpf, sockhash:
Synchronize delete from bucket list on map free")

[1]
refcount_t: decrement hit 0; leaking memory.
WARNING: CPU: 0 PID: 3785 at lib/refcount.c:31 refcount_warn_saturate+0x17c/0x1a0 lib/refcount.c:31
Modules linked in:
CPU: 0 PID: 3785 Comm: kworker/u4:6 Not tainted 6.1.0-rc7-syzkaller-00103-gef4d3ea4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: events_unbound bpf_map_free_deferred
RIP: 0010:refcount_warn_saturate+0x17c/0x1a0 lib/refcount.c:31
Code: 68 8b 31 c0 e8 75 71 15 fd 0f 0b e9 64 ff ff ff e8 d9 6e 4e fd c6 05 62 9c 3d 0a 01 48 c7 c7 80 bb 68 8b 31 c0 e8 54 71 15 fd <0f> 0b e9 43 ff ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c a2 fe ff
RSP: 0018:ffffc9000456fb60 EFLAGS: 00010246
RAX: eae59bab72dcd700 RBX: 0000000000000004 RCX: ffff8880207057c0
RDX: 0000000000000000 RSI: 0000000000000201 RDI: 0000000000000000
RBP: 0000000000000004 R08: ffffffff816fdabd R09: fffff520008adee5
R10: fffff520008adee5 R11: 1ffff920008adee4 R12: 0000000000000004
R13: dffffc0000000000 R14: ffff88807b1c6c00 R15: 1ffff1100f638dcf
FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30c30000 CR3: 000000000d08e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__refcount_dec include/linux/refcount.h:344 [inline]
refcount_dec include/linux/refcount.h:359 [inline]
__sock_put include/net/sock.h:779 [inline]
tcp_release_cb+0x2d0/0x360 net/ipv4/tcp_output.c:1092
release_sock+0xaf/0x1c0 net/core/sock.c:3468
sock_map_free+0x219/0x2c0 net/core/sock_map.c:356
process_one_work+0x81c/0xd10 kernel/workqueue.c:2289
worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
kthread+0x266/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>

Fixes: 7e81a353 ("bpf: Sockmap, ensure sock lock held during tear down")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Song Liu <songliubraving@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20221202111640.2745533-1-edumazet@google.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

The bpf_ct_set_nat_info() kfunc is defined in the nf_nat.ko module, and
takes as a parameter the nf_conn___init struct, which is allocated through
the bpf_xdp_ct_alloc() helper defined in the nf_conntrack.ko module.
However, because kernel modules can't deduplicate BTF types between each
other, and the nf_conn___init struct is not referenced anywhere in vmlinux
BTF, this leads to two distinct BTF IDs for the same type (one in each
module). This confuses the verifier, as described here:

https://lore.kernel.org/all/87leoh372s.fsf@toke.dk/

As a workaround, add an explicit BTF_TYPE_EMIT for the type in
net/filter.c, so the type definition gets included in vmlinux BTF. This
way, both modules can refer to the same type ID (as they both build on top
of vmlinux BTF), and the verifier is no longer confused.

v2:

- Use BTF_TYPE_EMIT (which is a statement so it has to be inside a function
  definition; use xdp_func_proto() for this, since this is mostly
  xdp-related).

Fixes: 820dc052 ("net: netfilter: move bpf_ct_set_nat_info kfunc in nf_nat_bpf.c")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20221201123939.696558-1-toke@redhat.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Add three tests for cgrp local storage support for sleepable progs.
Two tests can load and run properly, one for cgroup_iter, another
for passing current->cgroups->dfl_cgrp to bpf_cgrp_storage_get()
helper. One test has bpf_rcu_read_lock() and failed to load.
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221201050449.2785613-1-yhs@fb.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Similar to sk/inode/task local storage, enable sleepable support for
cgrp local storage.
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221201050444.2785007-1-yhs@fb.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Document that describes how BPF iterators work, how to use iterators,
and how to pass parameters in BPF iterators.
Acked-by: David Vernet <void@manifault.com>
Signed-off-by: Sreevani Sreejith <psreep@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221202221710.320810-2-ssreevani@meta.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Martin mentioned that the verifier cannot assume arguments from
LSM hook sk_alloc_security being trusted since after the hook
is called, the sk ref_count is set to 1. This will overwrite
the ref_count changed by the bpf program and may cause ref_count
underflow later on.

I then further checked some other hooks. For example,
for bpf_lsm_file_alloc() hook in fs/file_table.c,

        f->f_cred = get_cred(cred);
        error = security_file_alloc(f);
        if (unlikely(error)) {
                file_free_rcu(&f->f_rcuhead);
                return ERR_PTR(error);
        }

        atomic_long_set(&f->f_count, 1);

The input parameter 'f' to security_file_alloc() cannot be trusted
as well.

Specifically, I investiaged bpf_map/bpf_prog/file/sk/task alloc/free
lsm hooks. Except bpf_map_alloc and task_alloc, arguments for all other
hooks should not be considered as trusted. This may not be a complete
list, but it covers common usage for sk and task.

Fixes: 3f00c523 ("bpf: Allow trusted pointers to be passed to KF_TRUSTED_ARGS kfuncs")
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221203204954.2043348-1-yhs@fb.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>