| 1 | |
| 2 |
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| 3 | #include <linux/bpf.h>
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| 4 | #include <bpf/bpf_helpers.h>
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| 5 | #include "bpf_misc.h"
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| 6 |
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| 7 | |
| 8 | * Macro tricks to tersely define for long non-recursive call chains. Add
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| 9 | * computation to the functions prevent tail recursion from reducing the
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| 10 | * stack size to 0.
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| 11 |
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| 12 |
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| 13 | #define CAT(a, b) a ## b
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| 14 | #define XCAT(a, b) CAT(a, b)
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| 15 |
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| 16 | #define F_0 \
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| 17 | __attribute__((noinline)) \
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| 18 | int f0(unsigned long a) \
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| 19 | { \
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| 20 | volatile long b = a + 16; \
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| 21 | if (a == 0) \
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| 22 | return 0; \
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| 23 | return b; \
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| 24 | }
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| 25 |
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| 26 | #define FN(n, prev) \
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| 27 | __attribute__((noinline)) \
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| 28 | int XCAT(f, n)(unsigned long a) \
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| 29 | { \
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| 30 | volatile long b = XCAT(f, prev)(a - 1); \
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| 31 | if (!b) \
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| 32 | return 0; \
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| 33 | return b + 1; \
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| 34 | }
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| 35 |
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| 36 |
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| 37 | #define F_1 F_0 FN(1, 0)
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| 38 | #define F_2 F_1 FN(2, 1)
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| 39 | #define F_3 F_2 FN(3, 2)
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| 40 | #define F_4 F_3 FN(4, 3)
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| 41 | #define F_5 F_4 FN(5, 4)
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| 42 | #define F_6 F_5 FN(6, 5)
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| 43 | #define F_7 F_6 FN(7, 6)
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| 44 | #define F_8 F_7 FN(8, 7)
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| 45 | #define F_9 F_8 FN(9, 8)
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| 46 | #define F_10 F_9 FN(10, 9)
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| 47 | #define F_11 F_10 FN(11, 10)
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| 48 | #define F_12 F_11 FN(12, 11)
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| 49 | #define F_13 F_12 FN(13, 12)
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| 50 | #define F_14 F_13 FN(14, 13)
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| 51 | #define F_15 F_14 FN(15, 14)
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| 52 | #define F_16 F_15 FN(16, 15)
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| 53 | #define F_17 F_16 FN(17, 16)
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| 54 | #define F_18 F_17 FN(18, 17)
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| 55 | #define F_19 F_18 FN(19, 18)
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| 56 | #define F_20 F_19 FN(20, 19)
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| 57 | #define F_21 F_20 FN(21, 20)
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| 58 | #define F_22 F_21 FN(22, 21)
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| 59 | #define F_23 F_22 FN(23, 22)
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| 60 | #define F_24 F_23 FN(24, 23)
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| 61 | #define F_25 F_24 FN(25, 24)
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| 62 | #define F_26 F_25 FN(26, 25)
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| 63 | #define F_27 F_26 FN(27, 26)
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| 64 | #define F_28 F_27 FN(28, 27)
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| 65 | #define F_29 F_28 FN(29, 28)
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| 66 | #define F_30 F_29 FN(30, 29)
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| 67 | #define F_31 F_30 FN(31, 30)
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| 68 | #define F_32 F_31 FN(32, 31)
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| 69 |
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| 70 | #define CAT2(a, b) a ## b
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| 71 | #define XCAT2(a, b) CAT2(a, b)
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| 72 |
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| 73 | #define F(n) XCAT2(F_, n)
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| 74 |
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| 75 | F(32)
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| 76 |
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| 77 |
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| 78 | SEC("syscall")
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| 79 | __success
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| 80 | int global_func_deep_stack_success(struct __sk_buff *skb)
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| 81 | {
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| 82 | return f31(55);
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| 83 | }
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| 84 |
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| 85 | |
| 86 | * Check we actually honor stack limits (33 * 16 = 528 > 512 = MAX_STACK_DEPTH).
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| 87 | * The stack depth is 16 because the verifier calls round_up_stack_depth() on
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| 88 | * the size.
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| 89 |
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| 90 | SEC("syscall")
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| 91 | __failure __msg("combined stack size of 34 calls")
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| 92 | int global_func_deep_stack_fail(struct __sk_buff *skb)
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| 93 | {
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| 94 | return f32(123);
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| 95 | }
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