| 1 | // SPDX-License-Identifier: GPL-2.0 |
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| 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 | /* Read an uninitialized value from stack at a fixed offset */ |
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| 8 | SEC("socket" ) |
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| 9 | __naked int read_uninit_stack_fixed_off(void *ctx) |
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| 10 | { |
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| 11 | asm volatile (" \ |
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| 12 | r0 = 0; \ |
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| 13 | /* force stack depth to be 128 */ \ |
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| 14 | *(u64*)(r10 - 128) = r1; \ |
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| 15 | r1 = *(u8 *)(r10 - 8 ); \ |
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| 16 | r0 += r1; \ |
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| 17 | r1 = *(u8 *)(r10 - 11); \ |
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| 18 | r1 = *(u8 *)(r10 - 13); \ |
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| 19 | r1 = *(u8 *)(r10 - 15); \ |
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| 20 | r1 = *(u16*)(r10 - 16); \ |
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| 21 | r1 = *(u32*)(r10 - 32); \ |
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| 22 | r1 = *(u64*)(r10 - 64); \ |
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| 23 | /* read from a spill of a wrong size, it is a separate \ |
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| 24 | * branch in check_stack_read_fixed_off() \ |
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| 25 | */ \ |
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| 26 | *(u32*)(r10 - 72) = r1; \ |
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| 27 | r1 = *(u64*)(r10 - 72); \ |
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| 28 | r0 = 0; \ |
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| 29 | exit; \ |
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| 30 | " |
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| 31 | ::: __clobber_all); |
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| 32 | } |
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| 33 | |
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| 34 | /* Read an uninitialized value from stack at a variable offset */ |
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| 35 | SEC("socket" ) |
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| 36 | __naked int read_uninit_stack_var_off(void *ctx) |
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| 37 | { |
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| 38 | asm volatile (" \ |
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| 39 | call %[bpf_get_prandom_u32]; \ |
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| 40 | /* force stack depth to be 64 */ \ |
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| 41 | *(u64*)(r10 - 64) = r0; \ |
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| 42 | r0 = -r0; \ |
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| 43 | /* give r0 a range [-31, -1] */ \ |
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| 44 | if r0 s<= -32 goto exit_%=; \ |
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| 45 | if r0 s>= 0 goto exit_%=; \ |
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| 46 | /* access stack using r0 */ \ |
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| 47 | r1 = r10; \ |
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| 48 | r1 += r0; \ |
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| 49 | r2 = *(u8*)(r1 + 0); \ |
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| 50 | exit_%=: r0 = 0; \ |
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| 51 | exit; \ |
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| 52 | " |
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| 53 | : |
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| 54 | : __imm(bpf_get_prandom_u32) |
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| 55 | : __clobber_all); |
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| 56 | } |
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| 57 | |
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| 58 | static __noinline void dummy(void) {} |
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| 59 | |
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| 60 | /* Pass a pointer to uninitialized stack memory to a helper. |
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| 61 | * Passed memory block should be marked as STACK_MISC after helper call. |
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| 62 | */ |
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| 63 | SEC("socket" ) |
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| 64 | __log_level(7) __msg("fp-104=mmmmmmmm" ) |
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| 65 | __naked int helper_uninit_to_misc(void *ctx) |
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| 66 | { |
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| 67 | asm volatile (" \ |
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| 68 | /* force stack depth to be 128 */ \ |
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| 69 | *(u64*)(r10 - 128) = r1; \ |
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| 70 | r1 = r10; \ |
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| 71 | r1 += -128; \ |
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| 72 | r2 = 32; \ |
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| 73 | call %[bpf_trace_printk]; \ |
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| 74 | /* Call to dummy() forces print_verifier_state(..., true), \ |
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| 75 | * thus showing the stack state, matched by __msg(). \ |
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| 76 | */ \ |
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| 77 | call %[dummy]; \ |
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| 78 | r0 = 0; \ |
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| 79 | exit; \ |
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| 80 | " |
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| 81 | : |
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| 82 | : __imm(bpf_trace_printk), |
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| 83 | __imm(dummy) |
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| 84 | : __clobber_all); |
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| 85 | } |
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| 86 | |
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| 87 | char _license[] SEC("license" ) = "GPL" ; |
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| 88 | |
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