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feat(host): bind capability profiles and IO limits #18

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172 changes: 150 additions & 22 deletions src/builtins/runtime/io.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
use std::fs::OpenOptions;
use std::future::Future;
use std::io::{Read, Write};
use std::path::{Path, PathBuf};
use std::pin::Pin;
use std::process::{Child, Command, Stdio};
use std::sync::atomic::{AtomicU32, Ordering};
Expand Down Expand Up @@ -204,7 +205,16 @@ pub(super) fn builtin_io_open(
path: &str,
mode: &str,
) -> VmResult<HostCallResult<i64>> {
let path = path.to_string();
let writes = match mode {
"r" => false,
"w" | "a" | "r+" | "w+" | "a+" => true,
other => {
return Err(VmError::HostError(format!(
"unsupported io_open mode '{other}', expected r/w/a/r+/w+/a+"
)));
}
};
let path = authorize_io_path(vm, path, writes)?;
let mode = mode.to_string();
let op_id = schedule_io_task(vm, None, move || {
let mut options = OpenOptions::new();
Expand Down Expand Up @@ -260,6 +270,16 @@ pub(super) fn builtin_io_popen(
"unsupported io_popen mode '{mode}', expected r or w"
)));
}
if vm
.host
.io_policy
.as_ref()
.is_some_and(|policy| !policy.allow_process)
{
return Err(VmError::HostError(
"io_popen requires the process capability".to_string(),
));
}
let command = command.to_string();
let mode = mode.to_string();
let op_id = schedule_io_task(vm, None, move || {
Expand Down Expand Up @@ -298,23 +318,31 @@ pub(super) fn builtin_io_popen(
/// Reads all remaining text from an I/O handle.
#[pd_host_function(name = "io::read_all")]
pub(super) fn builtin_io_read_all(vm: &mut Vm, handle_id: i64) -> VmResult<HostCallResult<String>> {
let max_read_bytes = vm
.host
.io_policy
.as_ref()
.map(|policy| policy.max_read_bytes);
let handle = resource_handle(handle_id)?;
let resource = io_resource_for_handle(vm, handle)?;
let op_id = schedule_io_task(vm, Some(handle), move || {
let result = resource.with_handle_mut(|handle| {
let mut out = String::new();
match handle {
IoHandle::File(file) => file
.read_to_string(&mut out)
.map_err(|err| VmError::HostError(format!("io_read_all failed: {err}")))?,
IoHandle::PopenRead { child } => child
.stdout
.as_mut()
.ok_or_else(|| {
VmError::HostError("io_read_all popen handle missing stdout".to_string())
})?
.read_to_string(&mut out)
.map_err(|err| VmError::HostError(format!("io_read_all failed: {err}")))?,
IoHandle::File(file) => {
read_to_string_with_limit(file, max_read_bytes, &mut out)?;
}
IoHandle::PopenRead { child } => {
read_to_string_with_limit(
child.stdout.as_mut().ok_or_else(|| {
VmError::HostError(
"io_read_all popen handle missing stdout".to_string(),
)
})?,
max_read_bytes,
&mut out,
)?;
}
IoHandle::PopenWrite { .. } => {
return Err(VmError::HostError(
"io_read_all requires a readable handle".to_string(),
Expand All @@ -334,17 +362,23 @@ pub(super) fn builtin_io_read_line(
vm: &mut Vm,
handle_id: i64,
) -> VmResult<HostCallResult<String>> {
let max_read_bytes = vm
.host
.io_policy
.as_ref()
.map(|policy| policy.max_read_bytes);
let handle = resource_handle(handle_id)?;
let resource = io_resource_for_handle(vm, handle)?;
let op_id = schedule_io_task(vm, Some(handle), move || {
let result = resource.with_handle_mut(|handle| {
let line = match handle {
IoHandle::File(file) => read_line_from_reader(file)?,
IoHandle::PopenRead { child } => {
read_line_from_reader(child.stdout.as_mut().ok_or_else(|| {
IoHandle::File(file) => read_line_from_reader(file, max_read_bytes)?,
IoHandle::PopenRead { child } => read_line_from_reader(
child.stdout.as_mut().ok_or_else(|| {
VmError::HostError("io_read_line popen handle missing stdout".to_string())
})?)?
}
})?,
max_read_bytes,
)?,
IoHandle::PopenWrite { .. } => {
return Err(VmError::HostError(
"io_read_line requires a readable handle".to_string(),
Expand All @@ -365,6 +399,14 @@ pub(super) fn builtin_io_write(
handle_id: i64,
text: &str,
) -> VmResult<HostCallResult<i64>> {
if let Some(policy) = vm.host.io_policy.as_ref()
&& text.len() > policy.max_write_bytes
{
return Err(VmError::HostError(format!(
"io_write exceeds the configured write limit of {} bytes",
policy.max_write_bytes
)));
}
let bytes = text.as_bytes().to_vec();
let handle = resource_handle(handle_id)?;
let resource = io_resource_for_handle(vm, handle)?;
Expand Down Expand Up @@ -445,15 +487,65 @@ pub(super) fn builtin_io_close(vm: &mut Vm, handle_id: i64) -> VmResult<HostCall
/// Returns whether a file system path exists.
#[pd_host_function(name = "io::exists")]
pub(super) fn builtin_io_exists(vm: &mut Vm, path: &str) -> VmResult<HostCallResult<bool>> {
let path = path.to_string();
let path = authorize_io_path(vm, path, false)?;
let op_id = schedule_io_task(vm, None, move || {
IoAsyncCompletion::result(Ok(CallReturn::one(Value::Bool(
std::path::Path::new(path.as_str()).exists(),
))))
IoAsyncCompletion::result(Ok(CallReturn::one(Value::Bool(path.exists()))))
})?;
Ok(HostCallResult::Pending(op_id))
}

fn authorize_io_path(vm: &Vm, path: &str, writes: bool) -> VmResult<PathBuf> {
let requested = PathBuf::from(path);
let Some(policy) = vm.host.io_policy.as_ref() else {
return Ok(requested);
};
if writes && !policy.allow_write {
return Err(VmError::HostError(
"io path write requires the write capability".to_string(),
));
}
let absolute = if requested.is_absolute() {
requested
} else {
std::env::current_dir()
.map_err(|error| VmError::HostError(format!("io path resolution failed: {error}")))?
.join(requested)
};
let canonical = canonicalize_io_target(&absolute)?;
for root in &policy.allowed_roots {
let root = Path::new(root).canonicalize().map_err(|error| {
VmError::HostError(format!(
"io allowed root '{root}' cannot be resolved: {error}"
))
})?;
if canonical.starts_with(root) {
return Ok(canonical);
}
}
Err(VmError::HostError(format!(
"io path '{}' is outside the allowed roots",
canonical.display()
)))
}

fn canonicalize_io_target(path: &Path) -> VmResult<PathBuf> {
if path.exists() {
return path
.canonicalize()
.map_err(|error| VmError::HostError(format!("io path resolution failed: {error}")));
}
let parent = path
.parent()
.ok_or_else(|| VmError::HostError(format!("io path '{}' has no parent", path.display())))?;
let file_name = path.file_name().ok_or_else(|| {
VmError::HostError(format!("io path '{}' has no file name", path.display()))
})?;
parent
.canonicalize()
.map(|parent| parent.join(file_name))
.map_err(|error| VmError::HostError(format!("io path resolution failed: {error}")))
}

fn spawn_shell_command(command: &str, mode: &str) -> VmResult<Child> {
let mut process = if cfg!(windows) {
let mut cmd = Command::new("cmd");
Expand Down Expand Up @@ -882,7 +974,37 @@ fn terminate_process_tree(process_id: u32) -> VmResult<()> {
)))
}

fn read_line_from_reader(reader: &mut impl Read) -> VmResult<String> {
fn read_to_string_with_limit(
reader: &mut impl Read,
max_read_bytes: Option<usize>,
out: &mut String,
) -> VmResult<()> {
match max_read_bytes {
None => {
reader
.read_to_string(out)
.map_err(|err| VmError::HostError(format!("io_read_all failed: {err}")))?;
}
Some(limit) => {
let take_limit = u64::try_from(limit).unwrap_or(u64::MAX).saturating_add(1);
reader
.take(take_limit)
.read_to_string(out)
.map_err(|err| VmError::HostError(format!("io_read_all failed: {err}")))?;
if out.len() > limit {
return Err(VmError::HostError(format!(
"io_read_all exceeds the configured read limit of {limit} bytes"
)));
}
}
}
Ok(())
}

fn read_line_from_reader(
reader: &mut impl Read,
max_read_bytes: Option<usize>,
) -> VmResult<String> {
let mut bytes = Vec::new();
let mut one = [0u8; 1];
loop {
Expand All @@ -893,6 +1015,12 @@ fn read_line_from_reader(reader: &mut impl Read) -> VmResult<String> {
break;
}
bytes.push(one[0]);
if max_read_bytes.is_some_and(|limit| bytes.len() > limit) {
return Err(VmError::HostError(format!(
"io_read_line exceeds the configured read limit of {} bytes",
max_read_bytes.expect("read limit should be present")
)));
}
if one[0] == b'\n' {
break;
}
Expand Down
13 changes: 7 additions & 6 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -88,12 +88,13 @@ pub use jit::{
pub use vm::diagnostics::render_vm_error;
#[cfg(feature = "runtime")]
pub use vm::{
AotArtifactError, CallOutcome, CallReturn, CancellationReason, DEFAULT_MAX_SCRIPT_CALL_DEPTH,
EpochCheckpoint, EpochHandle, FuelCheckpoint, HostArgsFunction, HostAsyncBridge,
HostBindingPlan, HostFunction, HostFunctionRegistry, HostOpId, HostStackFunction,
IntoScriptValue, QueuedScriptInvocation, ScriptArgs, ScriptCallback, ScriptResult,
StaticHostArgsFunction, StaticHostFunction, StaticHostStackFunction, Store, Vm, VmError,
VmResult, VmStatus, VmYieldReason,
AotArtifactError, CallOutcome, CallReturn, CancellationReason, CapabilityProfile,
CapabilityProfileBuilder, DEFAULT_MAX_SCRIPT_CALL_DEPTH, EpochCheckpoint, EpochHandle,
FuelCheckpoint, HostArgsFunction, HostAsyncBridge, HostBindingPlan, HostFunction,
HostFunctionRegistry, HostOpId, HostStackFunction, IntoScriptValue, IoPolicy,
QueuedScriptInvocation, ScriptArgs, ScriptCallback, ScriptResult, StaticHostArgsFunction,
StaticHostFunction, StaticHostStackFunction, Store, Vm, VmError, VmResult, VmStatus,
VmYieldReason,
};
#[cfg(feature = "sqlite")]
pub use vm::{SqliteLimits, SqlitePolicy};
Expand Down
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