forked from Minki/linux
7105e828c0
Currently a dump of an xlated prog (post verifier stage) doesn't
correlate used helpers as well as maps. The prog info lists
involved map ids, however there's no correlation of where in the
program they are used as of today. Likewise, bpftool does not
correlate helper calls with the target functions.
The latter can be done w/o any kernel changes through kallsyms,
and also has the advantage that this works with inlined helpers
and BPF calls.
Example, via interpreter:
# tc filter show dev foo ingress
filter protocol all pref 49152 bpf chain 0
filter protocol all pref 49152 bpf chain 0 handle 0x1 foo.o:[ingress] \
direct-action not_in_hw id 1 tag c74773051b364165 <-- prog id:1
* Output before patch (calls/maps remain unclear):
# bpftool prog dump xlated id 1 <-- dump prog id:1
0: (b7) r1 = 2
1: (63) *(u32 *)(r10 -4) = r1
2: (bf) r2 = r10
3: (07) r2 += -4
4: (18) r1 = 0xffff95c47a8d4800
6: (85) call unknown#73040
7: (15) if r0 == 0x0 goto pc+18
8: (bf) r2 = r10
9: (07) r2 += -4
10: (bf) r1 = r0
11: (85) call unknown#73040
12: (15) if r0 == 0x0 goto pc+23
[...]
* Output after patch:
# bpftool prog dump xlated id 1
0: (b7) r1 = 2
1: (63) *(u32 *)(r10 -4) = r1
2: (bf) r2 = r10
3: (07) r2 += -4
4: (18) r1 = map[id:2] <-- map id:2
6: (85) call bpf_map_lookup_elem#73424 <-- helper call
7: (15) if r0 == 0x0 goto pc+18
8: (bf) r2 = r10
9: (07) r2 += -4
10: (bf) r1 = r0
11: (85) call bpf_map_lookup_elem#73424
12: (15) if r0 == 0x0 goto pc+23
[...]
# bpftool map show id 2 <-- show/dump/etc map id:2
2: hash_of_maps flags 0x0
key 4B value 4B max_entries 3 memlock 4096B
Example, JITed, same prog:
# tc filter show dev foo ingress
filter protocol all pref 49152 bpf chain 0
filter protocol all pref 49152 bpf chain 0 handle 0x1 foo.o:[ingress] \
direct-action not_in_hw id 3 tag c74773051b364165 jited
# bpftool prog show id 3
3: sched_cls tag c74773051b364165
loaded_at Dec 19/13:48 uid 0
xlated 384B jited 257B memlock 4096B map_ids 2
# bpftool prog dump xlated id 3
0: (b7) r1 = 2
1: (63) *(u32 *)(r10 -4) = r1
2: (bf) r2 = r10
3: (07) r2 += -4
4: (18) r1 = map[id:2] <-- map id:2
6: (85) call __htab_map_lookup_elem#77408 <-+ inlined rewrite
7: (15) if r0 == 0x0 goto pc+2 |
8: (07) r0 += 56 |
9: (79) r0 = *(u64 *)(r0 +0) <-+
10: (15) if r0 == 0x0 goto pc+24
11: (bf) r2 = r10
12: (07) r2 += -4
[...]
Example, same prog, but kallsyms disabled (in that case we are
also not allowed to pass any relative offsets, etc, so prog
becomes pointer sanitized on dump):
# sysctl kernel.kptr_restrict=2
kernel.kptr_restrict = 2
# bpftool prog dump xlated id 3
0: (b7) r1 = 2
1: (63) *(u32 *)(r10 -4) = r1
2: (bf) r2 = r10
3: (07) r2 += -4
4: (18) r1 = map[id:2]
6: (85) call bpf_unspec#0
7: (15) if r0 == 0x0 goto pc+2
[...]
Example, BPF calls via interpreter:
# bpftool prog dump xlated id 1
0: (85) call pc+2#__bpf_prog_run_args32
1: (b7) r0 = 1
2: (95) exit
3: (b7) r0 = 2
4: (95) exit
Example, BPF calls via JIT:
# sysctl net.core.bpf_jit_enable=1
net.core.bpf_jit_enable = 1
# sysctl net.core.bpf_jit_kallsyms=1
net.core.bpf_jit_kallsyms = 1
# bpftool prog dump xlated id 1
0: (85) call pc+2#bpf_prog_3b185187f1855c4c_F
1: (b7) r0 = 1
2: (95) exit
3: (b7) r0 = 2
4: (95) exit
And finally, an example for tail calls that is now working
as well wrt correlation:
# bpftool prog dump xlated id 2
[...]
10: (b7) r2 = 8
11: (85) call bpf_trace_printk#-41312
12: (bf) r1 = r6
13: (18) r2 = map[id:1]
15: (b7) r3 = 0
16: (85) call bpf_tail_call#12
17: (b7) r1 = 42
18: (6b) *(u16 *)(r6 +46) = r1
19: (b7) r0 = 0
20: (95) exit
# bpftool map show id 1
1: prog_array flags 0x0
key 4B value 4B max_entries 1 memlock 4096B
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
52 lines
1.5 KiB
C
52 lines
1.5 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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* Copyright (c) 2016 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#ifndef __BPF_DISASM_H__
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#define __BPF_DISASM_H__
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#include <linux/bpf.h>
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#include <linux/kernel.h>
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#include <linux/stringify.h>
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#ifndef __KERNEL__
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#include <stdio.h>
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#include <string.h>
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#endif
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struct bpf_verifier_env;
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extern const char *const bpf_alu_string[16];
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extern const char *const bpf_class_string[8];
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const char *func_id_name(int id);
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typedef void (*bpf_insn_print_t)(struct bpf_verifier_env *env,
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const char *, ...);
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typedef const char *(*bpf_insn_revmap_call_t)(void *private_data,
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const struct bpf_insn *insn);
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typedef const char *(*bpf_insn_print_imm_t)(void *private_data,
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const struct bpf_insn *insn,
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__u64 full_imm);
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struct bpf_insn_cbs {
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bpf_insn_print_t cb_print;
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bpf_insn_revmap_call_t cb_call;
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bpf_insn_print_imm_t cb_imm;
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void *private_data;
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};
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void print_bpf_insn(const struct bpf_insn_cbs *cbs,
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struct bpf_verifier_env *env,
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const struct bpf_insn *insn,
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bool allow_ptr_leaks);
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#endif
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