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