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feature_gates.h
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feature_gates.h
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/*
Copyright (C) 2022 The Falco Authors.
This file is dual licensed under either the MIT or GPL 2. See MIT.txt
or GPL2.txt for full copies of the license.
*/
#ifndef FEATURE_GATES_H
#define FEATURE_GATES_H
/* FEATURE GATES:
*
* These feature gates are used by:
* - kernel module
* - BPF probe
* - userspace
* to compile out some features. The userspace is in charge of
* filling the BPF maps that's why it also needs these macros.
*
* This file is included by the 2 drivers and the userspace so
* it could be the right place to define these feature gates.
*/
#ifdef __KERNEL__ /* Kernel module - BPF probe */
#include <linux/version.h>
///////////////////////////////
// CAPTURE_SCHED_PROC_FORK
///////////////////////////////
/* In some architectures we are not able to catch the `clone exit child
* event` from the `sys_exit` tracepoint. This is because there is no
* default behavior among different architectures... you can find more
* info here:
* https://www.spinics.net/lists/linux-trace/msg01001.html
*
* Anyway, to not lose this event, we need to instrument a new kernel tracepoint:
*
* - `sched_process_fork`: allows us to catch every new process that is spawned.
*
* In this way we can detect when a child is spawned and we can send to userspace
* a `PPME_SYSCALL_CLONE_X` event as we do with the `sys_exit` tracepoint.
*
* Please note: in BPF we need to use raw_tracepoint programs to access
* the raw tracepoint arguments! This is essential for `sched_process_fork`
* tracepoint since the only way we have to access the child task struct
* is through its raw arguments. All the architectures that need this
* patch can use our BPF probe only with kernel versions greater or equal
* than `4.17`, since `BPF_PROG_TYPE_RAW_TRACEPOINT` programs have been
* introduced in this kernel release:
* https://github.com/torvalds/linux/commit/c4f6699dfcb8558d138fe838f741b2c10f416cf9
*
* If you run old kernels, you can use the kernel module which requires
* kernel versions greater or equal than `2.6`, since this tracepoint has
* been introduced in the following kernel release:
* https://github.com/torvalds/linux/commit/0a16b6075843325dc402edf80c1662838b929aff
*/
#if defined(CONFIG_ARM64) || defined(CONFIG_S390)
#define CAPTURE_SCHED_PROC_FORK
#endif
///////////////////////////////
// CAPTURE_SCHED_PROC_EXEC
///////////////////////////////
/* In some architectures we are not able to catch the `execve exit event`
* from the `sys_exit` tracepoint. This is because there is no
* default behavior among different architectures... you can find more
* info here:
* https://www.spinics.net/lists/linux-trace/msg01001.html
*
* Anyway, to not lose this event, we need to instrument a new kernel tracepoint:
*
* - `sched_process_exec`: allows us to catch every process that correctly performs
* an `execve` call.
*
* In this way we can send to userspace a `PPME_SYSCALL_EXECVE_X` event
* as we do with the `sys_exit` tracepoint.
*
* All the architectures that need this patch can use our BPF probe with all
* supported kernel versions (so >= `4.14`), since `BPF_PROG_TYPE_RAW_TRACEPOINT` are
* not required in this case.
*
* If you run old kernels, you can use the kernel module which requires
* kernel versions greater or equal than `3.4`, since this tracepoint has
* been introduced in the following kernel release:
* https://github.com/torvalds/linux/commit/4ff16c25e2cc48cbe6956e356c38a25ac063a64d
*/
#if defined(CONFIG_ARM64)
#define CAPTURE_SCHED_PROC_EXEC
#endif
///////////////////////////////
// CAPTURE_64BIT_ARGS_SINGLE_REGISTER
///////////////////////////////
/* This is described in syscall(2). Some syscalls take 64-bit arguments. On
* arches that have 64-bit registers, these arguments are shipped in a register.
* On 32-bit arches, however, these are split between two consecutive registers,
* with some alignment requirements. Some require an odd/even pair while some
* others require even/odd. For now, I assume they all do what x86_32 does, and
* we can handle the rest when we port those.
*/
#ifdef CONFIG_64BIT
#define CAPTURE_64BIT_ARGS_SINGLE_REGISTER
#endif /* CONFIG_64BIT */
///////////////////////////////
// CAPTURE_CONTEXT_SWITCHES
///////////////////////////////
#define CAPTURE_CONTEXT_SWITCHES
///////////////////////////////
// CAPTURE_SIGNAL_DELIVERIES
///////////////////////////////
#if (LINUX_VERSION_CODE > KERNEL_VERSION(2, 6, 32))
#define CAPTURE_SIGNAL_DELIVERIES
#endif
///////////////////////////////
// CAPTURE_PAGE_FAULTS
///////////////////////////////
#if (LINUX_VERSION_CODE > KERNEL_VERSION(3, 12, 0)) && defined(CONFIG_X86)
#define CAPTURE_PAGE_FAULTS
#endif
#else /* Userspace */
/* Please note: the userspace loads the filler table for the bpf probe
* so it must define these macro according to what BPF supports
*/
#ifndef UDIG
///////////////////////////////
// CAPTURE_64BIT_ARGS_SINGLE_REGISTER
///////////////////////////////
#if defined(__x86_64__) || defined(__aarch64__)
#define CAPTURE_64BIT_ARGS_SINGLE_REGISTER
#endif
///////////////////////////////
// CAPTURE_CONTEXT_SWITCHES
///////////////////////////////
#define CAPTURE_CONTEXT_SWITCHES
///////////////////////////////
// CAPTURE_SIGNAL_DELIVERIES
///////////////////////////////
#define CAPTURE_SIGNAL_DELIVERIES
///////////////////////////////
// CAPTURE_PAGE_FAULTS
///////////////////////////////
#ifdef __x86_64__
#define CAPTURE_PAGE_FAULTS
#endif /* __x86_64__ */
#endif /* UDIG */
#endif /* __KERNEL__ */
#endif /* FEATURE_GATES_H */