bpf/progs/find_vma.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /* Copyright (c) 2021 Facebook */
0003 #include "vmlinux.h"
0004 #include <bpf/bpf_helpers.h>
0005 #include <bpf/bpf_tracing.h>
0006
0007 char _license[] SEC("license") = "GPL";
0008
0009 struct callback_ctx {
0010     int dummy;
0011 };
0012
0013 #define VM_EXEC     0x00000004
0014 #define DNAME_INLINE_LEN 32
0015
0016 pid_t target_pid = 0;
0017 char d_iname[DNAME_INLINE_LEN] = {0};
0018 __u32 found_vm_exec = 0;
0019 __u64 addr = 0;
0020 int find_zero_ret = -1;
0021 int find_addr_ret = -1;
0022
0023 static long check_vma(struct task_struct *task, struct vm_area_struct *vma,
0024               struct callback_ctx *data)
0025 {
0026     if (vma->vm_file)
0027         bpf_probe_read_kernel_str(d_iname, DNAME_INLINE_LEN - 1,
0028                       vma->vm_file->f_path.dentry->d_iname);
0029
0030     /* check for VM_EXEC */
0031     if (vma->vm_flags & VM_EXEC)
0032         found_vm_exec = 1;
0033
0034     return 0;
0035 }
0036
0037 SEC("raw_tp/sys_enter")
0038 int handle_getpid(void)
0039 {
0040     struct task_struct *task = bpf_get_current_task_btf();
0041     struct callback_ctx data = {};
0042
0043     if (task->pid != target_pid)
0044         return 0;
0045
0046     find_addr_ret = bpf_find_vma(task, addr, check_vma, &data, 0);
0047
0048     /* this should return -ENOENT */
0049     find_zero_ret = bpf_find_vma(task, 0, check_vma, &data, 0);
0050     return 0;
0051 }
0052
0053 SEC("perf_event")
0054 int handle_pe(void)
0055 {
0056     struct task_struct *task = bpf_get_current_task_btf();
0057     struct callback_ctx data = {};
0058
0059     if (task->pid != target_pid)
0060         return 0;
0061
0062     find_addr_ret = bpf_find_vma(task, addr, check_vma, &data, 0);
0063
0064     /* In NMI, this should return -EBUSY, as the previous call is using
0065      * the irq_work.
0066      */
0067     find_zero_ret = bpf_find_vma(task, 0, check_vma, &data, 0);
0068     return 0;
0069 }