| 1 | // SPDX-License-Identifier: GPL-2.0 |
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| 2 | /* Copyright (C) 2021. Huawei Technologies Co., Ltd */ |
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| 3 | #include <stdbool.h> |
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| 4 | #include <linux/types.h> |
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| 5 | #include <linux/bpf.h> |
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| 6 | #include <bpf/bpf_helpers.h> |
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| 7 | #include <bpf/bpf_tracing.h> |
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| 8 | |
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| 9 | #define STRNCMP_STR_SZ 8 |
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| 10 | |
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| 11 | const char target[STRNCMP_STR_SZ] = "EEEEEEE" ; |
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| 12 | char str[STRNCMP_STR_SZ]; |
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| 13 | int cmp_ret = 0; |
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| 14 | int target_pid = 0; |
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| 15 | |
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| 16 | const char no_str_target[STRNCMP_STR_SZ] = "12345678" ; |
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| 17 | char writable_target[STRNCMP_STR_SZ]; |
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| 18 | unsigned int no_const_str_size = STRNCMP_STR_SZ; |
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| 19 | |
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| 20 | char _license[] SEC("license" ) = "GPL" ; |
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| 21 | |
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| 22 | SEC("?tp/syscalls/sys_enter_nanosleep" ) |
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| 23 | int do_strncmp(void *ctx) |
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| 24 | { |
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| 25 | if ((bpf_get_current_pid_tgid() >> 32) != target_pid) |
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| 26 | return 0; |
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| 27 | |
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| 28 | cmp_ret = bpf_strncmp(str, STRNCMP_STR_SZ, target); |
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| 29 | return 0; |
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| 30 | } |
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| 31 | |
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| 32 | SEC("?tp/syscalls/sys_enter_nanosleep" ) |
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| 33 | int strncmp_bad_not_const_str_size(void *ctx) |
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| 34 | { |
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| 35 | /* The value of string size is not const, so will fail */ |
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| 36 | cmp_ret = bpf_strncmp(str, no_const_str_size, target); |
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| 37 | return 0; |
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| 38 | } |
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| 39 | |
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| 40 | SEC("?tp/syscalls/sys_enter_nanosleep" ) |
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| 41 | int strncmp_bad_writable_target(void *ctx) |
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| 42 | { |
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| 43 | /* Compared target is not read-only, so will fail */ |
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| 44 | cmp_ret = bpf_strncmp(str, STRNCMP_STR_SZ, writable_target); |
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| 45 | return 0; |
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| 46 | } |
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| 47 | |
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| 48 | SEC("?tp/syscalls/sys_enter_nanosleep" ) |
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| 49 | int strncmp_bad_not_null_term_target(void *ctx) |
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| 50 | { |
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| 51 | /* Compared target is not null-terminated, so will fail */ |
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| 52 | cmp_ret = bpf_strncmp(str, STRNCMP_STR_SZ, no_str_target); |
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| 53 | return 0; |
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| 54 | } |
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| 55 | |
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