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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.fr
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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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>
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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.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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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.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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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.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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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: 4e814da0d599 ("bpf: Allow locking bpf_spin_lock in allocated objects")
Link: https://lore.kernel.org/r/20221206231000.3180914-2-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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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: 90660309b0c7 ("bpf: Add kfuncs for storing struct task_struct * as a kptr")
Fixes: fca1aa75518c ("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.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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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>
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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
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"=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
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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
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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/559
Signed-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
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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: 90a3a05eb33f ("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.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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strdup() allocates memory for path. We need to release the memory in the
following error path. Add free() to avoid memory leak.
Fixes: 8f184732b60b ("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
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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: 69c087ba6225 ("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
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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>
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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.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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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.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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TC-BPF
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.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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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.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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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-2
Signed-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.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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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 75e68e5bf2c7 ("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-gef4d3ea40565 #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: 7e81a3530206 ("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.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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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: 820dc0523e05 ("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.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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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.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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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.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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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.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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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: 3f00c5239344 ("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.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Yonghong Song says:
====================
Patch set [1] added rcu support for bpf programs. In [1], a rcu
pointer is considered to be trusted and not null. This is actually
not true in some cases. The rcu pointer could be null, and for non-null
rcu pointer, it may have reference count of 0. This small patch set
fixed this problem. Patch 1 is the kernel fix. Patch 2 adjusted
selftests properly. Patch 3 added documentation for newly-introduced
KF_RCU flag.
[1] https://lore.kernel.org/all/20221124053201.2372298-1-yhs@fb.com/
Changelogs:
v1 -> v2:
- rcu ptr could be NULL.
- non_null_rcu_ptr->rcu_field can be marked as MEM_RCU as well.
- Adjust the code to avoid existing error message change.
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Add proper KF_RCU documentation in kfuncs.rst.
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221203184613.478967-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Add MEM_RCU pointer null checking for related tests. Also
modified task_acquire test so it takes a rcu ptr 'ptr' where
'ptr = rcu_ptr->rcu_field'.
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221203184607.478314-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Commit 9bb00b2895cb ("bpf: Add kfunc bpf_rcu_read_lock/unlock()")
introduced MEM_RCU and bpf_rcu_read_lock/unlock() support. In that
commit, a rcu pointer is tagged with both MEM_RCU and PTR_TRUSTED
so that it can be passed into kfuncs or helpers as an argument.
Martin raised a good question in [1] such that the rcu pointer,
although being able to accessing the object, might have reference
count of 0. This might cause a problem if the rcu pointer is passed
to a kfunc which expects trusted arguments where ref count should
be greater than 0.
This patch makes the following changes related to MEM_RCU pointer:
- MEM_RCU pointer might be NULL (PTR_MAYBE_NULL).
- Introduce KF_RCU so MEM_RCU ptr can be acquired with
a KF_RCU tagged kfunc which assumes ref count of rcu ptr
could be zero.
- For mem access 'b = ptr->a', say 'ptr' is a MEM_RCU ptr, and
'a' is tagged with __rcu as well. Let us mark 'b' as
MEM_RCU | PTR_MAYBE_NULL.
[1] https://lore.kernel.org/bpf/ac70f574-4023-664e-b711-e0d3b18117fd@linux.dev/
Fixes: 9bb00b2895cb ("bpf: Add kfunc bpf_rcu_read_lock/unlock()")
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221203184602.477272-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Current libbpf Makefile does not contain the help command, which
is inconvenient to use. Similar to the Makefile help command of the
perf, a help command is provided to list the commands supported by
libbpf make and the functions of the commands.
Signed-off-by: Xin Liu <liuxin350@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221202081738.128513-1-liuxin350@huawei.com
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The bpf_legacy.h header uses llvm specific load functions, add
GCC compatible variants as well to fix tests using these functions
under GCC.
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221201190939.3230513-1-james.hilliard1@gmail.com
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Refer to description of BPF_XOR, dst_reg should be used but not src_reg
in the examples.
Fixes: be3193cded9d ("bpf, docs: Add subsections for ALU and JMP instructions")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221129134558.2757043-1-zhengyejian1@huawei.com
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Modify list_push_pop_multiple to alloc and insert nodes 2-at-a-time.
Without the previous patch's fix, this block of code:
bpf_spin_lock(lock);
bpf_list_push_front(head, &f[i]->node);
bpf_list_push_front(head, &f[i + 1]->node);
bpf_spin_unlock(lock);
would fail check_reference_leak check as release_on_unlock logic would miss
a ref that should've been released.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221201183406.1203621-2-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Consider a verifier state with three acquired references, all with
release_on_unlock = true:
idx 0 1 2
state->refs = [2 4 6]
(with 2, 4, and 6 being the ref ids).
When bpf_spin_unlock is called, process_spin_lock will loop through all
acquired_refs and, for each ref, if it's release_on_unlock, calls
release_reference on it. That function in turn calls
release_reference_state, which removes the reference from state->refs by
swapping the reference state with the last reference state in
refs array and decrements acquired_refs count.
process_spin_lock's loop logic, which is essentially:
for (i = 0; i < state->acquired_refs; i++) {
if (!state->refs[i].release_on_unlock)
continue;
release_reference(state->refs[i].id);
}
will fail to release release_on_unlock references which are swapped from
the end. Running this logic on our example demonstrates:
state->refs = [2 4 6] (start of idx=0 iter)
release state->refs[0] by swapping w/ state->refs[2]
state->refs = [6 4] (start of idx=1)
release state->refs[1], no need to swap as it's the last idx
state->refs = [6] (start of idx=2, loop terminates)
ref_id 6 should have been removed but was skipped.
Fix this by looping from back-to-front, which results in refs that are
candidates for removal being swapped with refs which have already been
examined and kept.
If we modify our initial example such that ref 6 is replaced with ref 7,
which is _not_ release_on_unlock, and loop from the back, we'd see:
state->refs = [2 4 7] (start of idx=2)
state->refs = [2 4 7] (start of idx=1)
state->refs = [2 7] (start of idx=0, refs 7 and 4 swapped)
state->refs = [7] (after idx=0, 7 and 2 swapped, loop terminates)
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Fixes: 534e86bc6c66 ("bpf: Add 'release on unlock' logic for bpf_list_push_{front,back}")
Link: https://lore.kernel.org/r/20221201183406.1203621-1-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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When building the kernel with clang lto (CONFIG_LTO_CLANG_FULL=y), the
following compilation error will appear:
$ make LLVM=1 LLVM_IAS=1 -j
...
ld.lld: error: ld-temp.o <inline asm>:26889:1: symbol 'cgroup_storage_map_btf_ids' is already defined
cgroup_storage_map_btf_ids:;
^
make[1]: *** [/.../bpf-next/scripts/Makefile.vmlinux_o:61: vmlinux.o] Error 1
In local_storage.c, we have
BTF_ID_LIST_SINGLE(cgroup_storage_map_btf_ids, struct, bpf_local_storage_map)
Commit c4bcfb38a95e ("bpf: Implement cgroup storage available to
non-cgroup-attached bpf progs") added the above identical BTF_ID_LIST_SINGLE
definition in bpf_cgrp_storage.c. With duplicated definitions, llvm linker
complains with lto build.
Also, extracting btf_id of 'struct bpf_local_storage_map' is defined four times
for sk, inode, task and cgrp local storages. Let us define a single global one
with a different name than cgroup_storage_map_btf_ids, which also fixed
the lto compilation error.
Fixes: c4bcfb38a95e ("bpf: Implement cgroup storage available to non-cgroup-attached bpf progs")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221130052147.1591625-1-yhs@fb.com
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Currently, the ingress redirect is not covered in "txmsg test apply".
Signed-off-by: Pengcheng Yang <yangpc@wangsu.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/1669718441-2654-5-git-send-email-yangpc@wangsu.com
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Use apply_bytes on ingress redirect, when apply_bytes is less than
the length of msg data, some data may be skipped and lost in
bpf_tcp_ingress().
If there is still data in the scatterlist that has not been consumed,
we cannot move the msg iter.
Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Pengcheng Yang <yangpc@wangsu.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/1669718441-2654-4-git-send-email-yangpc@wangsu.com
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When redirecting, we use sk_msg_to_ingress() to get the BPF_F_INGRESS
flag from the msg->flags. If apply_bytes is used and it is larger than
the current data being processed, sk_psock_msg_verdict() will not be
called when sendmsg() is called again. At this time, the msg->flags is 0,
and we lost the BPF_F_INGRESS flag.
So we need to save the BPF_F_INGRESS flag in sk_psock and use it when
redirection.
Fixes: 8934ce2fd081 ("bpf: sockmap redirect ingress support")
Signed-off-by: Pengcheng Yang <yangpc@wangsu.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/1669718441-2654-3-git-send-email-yangpc@wangsu.com
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In tcp_bpf_send_verdict() redirection, the eval variable is assigned to
__SK_REDIRECT after the apply_bytes data is sent, if msg has more_data,
sock_put() will be called multiple times.
We should reset the eval variable to __SK_NONE every time more_data
starts.
This causes:
IPv4: Attempt to release TCP socket in state 1 00000000b4c925d7
------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 5 PID: 4482 at lib/refcount.c:25 refcount_warn_saturate+0x7d/0x110
Modules linked in:
CPU: 5 PID: 4482 Comm: sockhash_bypass Kdump: loaded Not tainted 6.0.0 #1
Hardware name: Red Hat KVM, BIOS 1.11.0-2.el7 04/01/2014
Call Trace:
<TASK>
__tcp_transmit_skb+0xa1b/0xb90
? __alloc_skb+0x8c/0x1a0
? __kmalloc_node_track_caller+0x184/0x320
tcp_write_xmit+0x22a/0x1110
__tcp_push_pending_frames+0x32/0xf0
do_tcp_sendpages+0x62d/0x640
tcp_bpf_push+0xae/0x2c0
tcp_bpf_sendmsg_redir+0x260/0x410
? preempt_count_add+0x70/0xa0
tcp_bpf_send_verdict+0x386/0x4b0
tcp_bpf_sendmsg+0x21b/0x3b0
sock_sendmsg+0x58/0x70
__sys_sendto+0xfa/0x170
? xfd_validate_state+0x1d/0x80
? switch_fpu_return+0x59/0xe0
__x64_sys_sendto+0x24/0x30
do_syscall_64+0x37/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Fixes: cd9733f5d75c ("tcp_bpf: Fix one concurrency problem in the tcp_bpf_send_verdict function")
Signed-off-by: Pengcheng Yang <yangpc@wangsu.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/1669718441-2654-2-git-send-email-yangpc@wangsu.com
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The networking programs typically don't require CAP_PERFMON, but through kfuncs
like bpf_cast_to_kern_ctx() they can access memory through PTR_TO_BTF_ID. In
such case enforce CAP_PERFMON.
Also make sure that only GPL programs can access kernel data structures.
All kfuncs require GPL already.
Also remove allow_ptr_to_map_access. It's the same as allow_ptr_leaks and
different name for the same check only causes confusion.
Fixes: fd264ca02094 ("bpf: Add a kfunc to type cast from bpf uapi ctx to kernel ctx")
Fixes: 50c6b8a9aea2 ("selftests/bpf: Add a test for btf_type_tag "percpu"")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221125220617.26846-1-alexei.starovoitov@gmail.com
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BPF CI fails for arm64 and s390x each with the following result:
[...]
All error logs:
serial_test_kprobe_multi_bench_attach:PASS:get_syms 0 nsec
serial_test_kprobe_multi_bench_attach:PASS:kprobe_multi_empty__open_and_load 0 nsec
libbpf: prog 'test_kprobe_empty': failed to attach: Operation not supported
serial_test_kprobe_multi_bench_attach:FAIL:bpf_program__attach_kprobe_multi_opts unexpected error: -95
#92 kprobe_multi_bench_attach:FAIL
[...]
Add the test to the deny list.
Fixes: 5b6c7e5c4434 ("selftests/bpf: Add attach bench test")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Just a simple test to make sure we don't introduce unwanted compiler
warnings and API still supports passing enums as input argument.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221130200013.2997831-2-andrii@kernel.org
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C++ enum forward declarations are fundamentally not compatible with pure
C enum definitions, and so libbpf's use of `enum bpf_stats_type;`
forward declaration in libbpf/bpf.h public API header is causing C++
compilation issues.
More details can be found in [0], but it comes down to C++ supporting
enum forward declaration only with explicitly specified backing type:
enum bpf_stats_type: int;
In C (and I believe it's a GCC extension also), such forward declaration
is simply:
enum bpf_stats_type;
Further, in Linux UAPI this enum is defined in pure C way:
enum bpf_stats_type { BPF_STATS_RUN_TIME = 0; }
And even though in both cases backing type is int, which can be
confirmed by looking at DWARF information, for C++ compiler actual enum
definition and forward declaration are incompatible.
To eliminate this problem, for C++ mode define input argument as int,
which makes enum unnecessary in libbpf public header. This solves the
issue and as demonstrated by next patch doesn't cause any unwanted
compiler warnings, at least with default warnings setting.
[0] https://stackoverflow.com/questions/42766839/c11-enum-forward-causes-underlying-type-mismatch
[1] Closes: https://github.com/libbpf/libbpf/issues/249
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221130200013.2997831-1-andrii@kernel.org
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btf_skc_cls_ingress
This patch removes the need to pin prog when attaching to tc ingress
in the btf_skc_cls_ingress test. Instead, directly use the
bpf_tc_hook_create() and bpf_tc_attach(). The qdisc clsact
will go away together with the netns, so no need to
bpf_tc_hook_destroy().
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20221129070900.3142427-8-martin.lau@linux.dev
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After removing the mount/umount dance from {open,close}_netns()
in the pervious patch, "serial_" can be removed from
the tests using {open,close}_netns().
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20221129070900.3142427-7-martin.lau@linux.dev
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The previous patches have removed the need to do the mount and umount
dance when switching netns. In particular:
* Avoid remounting /sys/fs/bpf to have a clean start
* Avoid remounting /sys to get a ifindex of a particular netns
This patch can finally remove the mount and umount dance in
{open,close}_netns which is unnecessarily complicated and
error-prone.
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20221129070900.3142427-6-martin.lau@linux.dev
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This patch removes the need to pin prog in the remaining tests in
tc_redirect.c by directly using the bpf_tc_hook_create() and
bpf_tc_attach(). The clsact qdisc will go away together with
the test netns, so no need to do bpf_tc_hook_destroy().
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20221129070900.3142427-5-martin.lau@linux.dev
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This patch removes the need to pin prog in the tc_redirect_peer_l3
test by directly using the bpf_tc_hook_create() and bpf_tc_attach().
The clsact qdisc will go away together with the test netns, so
no need to do bpf_tc_hook_destroy().
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20221129070900.3142427-4-martin.lau@linux.dev
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