1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207
// Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
//! This module defines the data structures used for the intermmediate representation (IR),
//! as well as the logic for compiling the filter into BPF code, the final form of the filter.
mod bpf;
mod condition;
mod filter;
mod rule;
pub use condition::SeccompCondition;
pub use filter::SeccompFilter;
pub use rule::SeccompRule;
#[cfg(feature = "json")]
use serde::Deserialize;
use core::fmt::Formatter;
use std::fmt::Display;
use bpf::{
ARG_NUMBER_MAX, AUDIT_ARCH_AARCH64, AUDIT_ARCH_X86_64, BPF_MAX_LEN, SECCOMP_RET_ALLOW,
SECCOMP_RET_ERRNO, SECCOMP_RET_KILL_PROCESS, SECCOMP_RET_KILL_THREAD, SECCOMP_RET_LOG,
SECCOMP_RET_MASK, SECCOMP_RET_TRACE, SECCOMP_RET_TRAP,
};
pub use bpf::{sock_filter, BpfProgram, BpfProgramRef};
/// Backend Result type.
type Result<T> = std::result::Result<T, Error>;
/// Backend-related errors.
#[derive(Debug, PartialEq, Eq)]
pub enum Error {
/// Attempting to associate an empty vector of conditions to a rule.
EmptyRule,
/// Filter exceeds the maximum number of instructions that a BPF program can have.
FilterTooLarge(usize),
/// Filter and default actions are equal.
IdenticalActions,
/// Argument index of a `SeccompCondition` exceeds the maximum linux syscall index.
InvalidArgumentNumber,
/// Invalid TargetArch.
InvalidTargetArch(String),
}
impl std::error::Error for Error {}
impl Display for Error {
fn fmt(&self, f: &mut Formatter) -> std::fmt::Result {
use self::Error::*;
match self {
EmptyRule => {
write!(f, "The condition vector of a rule cannot be empty.")
}
FilterTooLarge(len) => write!(
f,
"The seccomp filter contains too many BPF instructions: {}. Max length is {}.",
len, BPF_MAX_LEN
),
IdenticalActions => write!(f, "`match_action` and `mismatch_action` are equal."),
InvalidArgumentNumber => {
write!(
f,
"The seccomp rule contains an invalid argument index. Maximum index value: {}",
ARG_NUMBER_MAX
)
}
InvalidTargetArch(arch) => write!(f, "Invalid target arch: {}.", arch),
}
}
}
/// Supported target architectures.
#[allow(non_camel_case_types)]
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum TargetArch {
/// x86_64 arch
x86_64,
/// aarch64 arch
aarch64,
}
impl TargetArch {
/// Get the arch audit value. Used for the runtime arch check embedded in the BPF filter.
fn get_audit_value(self) -> u32 {
match self {
TargetArch::x86_64 => AUDIT_ARCH_X86_64,
TargetArch::aarch64 => AUDIT_ARCH_AARCH64,
}
}
}
impl TryFrom<&str> for TargetArch {
type Error = Error;
fn try_from(input: &str) -> Result<Self> {
match input.to_lowercase().as_str() {
"x86_64" => Ok(TargetArch::x86_64),
"aarch64" => Ok(TargetArch::aarch64),
_ => Err(Error::InvalidTargetArch(input.to_string())),
}
}
}
/// Comparison to perform when matching a condition.
#[cfg_attr(
feature = "json",
derive(Deserialize),
serde(rename_all = "snake_case")
)]
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum SeccompCmpOp {
/// Argument value is equal to the specified value.
Eq,
/// Argument value is greater than or equal to the specified value.
Ge,
/// Argument value is greater than specified value.
Gt,
/// Argument value is less than or equal to the specified value.
Le,
/// Argument value is less than specified value.
Lt,
/// Masked bits of argument value are equal to masked bits of specified value.
MaskedEq(u64),
/// Argument value is not equal to specified value.
Ne,
}
/// Seccomp argument value length.
#[cfg_attr(feature = "json", derive(Deserialize), serde(rename_all = "lowercase"))]
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum SeccompCmpArgLen {
/// Argument value length is 4 bytes.
Dword,
/// Argument value length is 8 bytes.
Qword,
}
/// Actions that a seccomp filter can return for a syscall.
#[cfg_attr(
feature = "json",
derive(Deserialize),
serde(rename_all = "snake_case")
)]
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum SeccompAction {
/// Allows syscall.
Allow,
/// Returns from syscall with specified error number.
Errno(u32),
/// Kills calling thread.
KillThread,
/// Kills calling process.
KillProcess,
/// Allows syscall after logging it.
Log,
/// Notifies tracing process of the caller with respective number.
Trace(u32),
/// Sends `SIGSYS` to the calling process.
Trap,
}
impl From<SeccompAction> for u32 {
/// Return codes of the BPF program for each action.
///
/// # Arguments
///
/// * `action` - The [`SeccompAction`] that the kernel will take.
///
/// [`SeccompAction`]: enum.SeccompAction.html
fn from(action: SeccompAction) -> Self {
match action {
SeccompAction::Allow => SECCOMP_RET_ALLOW,
SeccompAction::Errno(x) => SECCOMP_RET_ERRNO | (x & SECCOMP_RET_MASK),
SeccompAction::KillThread => SECCOMP_RET_KILL_THREAD,
SeccompAction::KillProcess => SECCOMP_RET_KILL_PROCESS,
SeccompAction::Log => SECCOMP_RET_LOG,
SeccompAction::Trace(x) => SECCOMP_RET_TRACE | (x & SECCOMP_RET_MASK),
SeccompAction::Trap => SECCOMP_RET_TRAP,
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_target_arch() {
assert!(TargetArch::try_from("invalid").is_err());
assert!(TargetArch::try_from("x8664").is_err());
assert_eq!(TargetArch::try_from("x86_64").unwrap(), TargetArch::x86_64);
assert_eq!(TargetArch::try_from("X86_64").unwrap(), TargetArch::x86_64);
assert_eq!(
TargetArch::try_from("aarch64").unwrap(),
TargetArch::aarch64
);
assert_eq!(
TargetArch::try_from("aARch64").unwrap(),
TargetArch::aarch64
);
}
}