| 1 | // SPDX-License-Identifier: GPL-2.0 |
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| 2 | /* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */ |
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| 3 | |
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| 4 | #include <linux/bpf.h> |
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| 5 | #include <time.h> |
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| 6 | #include <errno.h> |
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| 7 | #include <bpf/bpf_helpers.h> |
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| 8 | #include "bpf_misc.h" |
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| 9 | #include "bpf_tcp_helpers.h" |
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| 10 | |
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| 11 | char _license[] SEC("license" ) = "GPL" ; |
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| 12 | |
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| 13 | struct elem { |
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| 14 | struct bpf_timer t; |
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| 15 | }; |
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| 16 | |
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| 17 | struct { |
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| 18 | __uint(type, BPF_MAP_TYPE_ARRAY); |
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| 19 | __uint(max_entries, 1); |
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| 20 | __type(key, int); |
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| 21 | __type(value, struct elem); |
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| 22 | } timer_map SEC(".maps" ); |
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| 23 | |
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| 24 | __naked __noinline __used |
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| 25 | static unsigned long timer_cb_ret_bad() |
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| 26 | { |
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| 27 | asm volatile ( |
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| 28 | "call %[bpf_get_prandom_u32];" |
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| 29 | "if r0 s> 1000 goto 1f;" |
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| 30 | "r0 = 0;" |
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| 31 | "1:" |
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| 32 | "goto +0;" /* checkpoint */ |
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| 33 | /* async callback is expected to return 0, so branch above |
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| 34 | * skipping r0 = 0; should lead to a failure, but if exit |
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| 35 | * instruction doesn't enforce r0's precision, this callback |
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| 36 | * will be successfully verified |
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| 37 | */ |
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| 38 | "exit;" |
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| 39 | : |
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| 40 | : __imm(bpf_get_prandom_u32) |
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| 41 | : __clobber_common |
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| 42 | ); |
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| 43 | } |
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| 44 | |
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| 45 | SEC("fentry/bpf_fentry_test1" ) |
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| 46 | __log_level(2) |
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| 47 | __flag(BPF_F_TEST_STATE_FREQ) |
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| 48 | __failure |
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| 49 | /* check that fallthrough code path marks r0 as precise */ |
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| 50 | __msg("mark_precise: frame0: regs=r0 stack= before" ) |
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| 51 | __msg(": (85) call bpf_get_prandom_u32#7" ) /* anchor message */ |
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| 52 | /* check that branch code path marks r0 as precise */ |
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| 53 | __msg("mark_precise: frame0: regs=r0 stack= before " ) __msg(": (85) call bpf_get_prandom_u32#7" ) |
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| 54 | __msg("should have been in [0, 0]" ) |
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| 55 | long BPF_PROG2(test_bad_ret, int, a) |
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| 56 | { |
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| 57 | int key = 0; |
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| 58 | struct bpf_timer *timer; |
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| 59 | |
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| 60 | timer = bpf_map_lookup_elem(&timer_map, &key); |
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| 61 | if (timer) { |
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| 62 | bpf_timer_init(timer, &timer_map, CLOCK_BOOTTIME); |
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| 63 | bpf_timer_set_callback(timer, timer_cb_ret_bad); |
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| 64 | bpf_timer_start(timer, 1000, 0); |
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| 65 | } |
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| 66 | |
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| 67 | return 0; |
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| 68 | } |
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| 69 | |
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