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main: reset tty if starting the VM fails

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When I refactored this to centralise resetting the tty into
DeviceManager::drop, I tested that the tty was reset if an error
happened on the vmm thread, but not on the main thread.  It turns out
that if an error happened on the main thread, the process would just
exit, so drop handlers on other threads wouldn't get run.

To fix this, I've changed start_vmm() to write to the VMM's exit
eventfd and then join the thread if an error happens after the vmm
thread is started.

Fixes: b6feae0a ("vmm: only touch the tty flags if it's being used")
Signed-off-by: Alyssa Ross <hi@alyssa.is>
This commit is contained in:
Alyssa Ross 2023-04-27 12:43:57 +00:00 committed by Rob Bradford
parent c90a0ffff6
commit 21d40d7489
3 changed files with 47 additions and 30 deletions
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59
src/main.rs
View File

@ -8,7 +8,7 @@ extern crate event_monitor;
use argh::FromArgs;
use libc::EFD_NONBLOCK;
use log::LevelFilter;
use log::{warn, LevelFilter};
use option_parser::OptionParser;
use seccompiler::SeccompAction;
use signal_hook::consts::SIGSYS;
@ -33,6 +33,8 @@ enum Error {
#[cfg(feature = "guest_debug")]
#[error("Failed to create Debug EventFd: {0}")]
CreateDebugEventFd(#[source] std::io::Error),
#[error("Failed to create exit EventFd: {0}")]
CreateExitEventFd(#[source] std::io::Error),
#[error("Failed to open hypervisor interface (is hypervisor interface available?): {0}")]
CreateHypervisor(#[source] hypervisor::HypervisorError),
#[error("Failed to start the VMM thread: {0}")]
@ -509,6 +511,8 @@ fn start_vmm(toplevel: TopLevel) -> Result<Option<String>, Error> {
#[cfg(feature = "guest_debug")]
let vm_debug_evt = EventFd::new(EFD_NONBLOCK).map_err(Error::CreateDebugEventFd)?;
let exit_evt = EventFd::new(EFD_NONBLOCK).map_err(Error::CreateExitEventFd)?;
let vmm_thread = vmm::start_vmm_thread(
vmm::VmmVersionInfo::new(env!("BUILD_VERSION"), env!("CARGO_PKG_VERSION")),
&api_socket_path,
@ -522,33 +526,46 @@ fn start_vmm(toplevel: TopLevel) -> Result<Option<String>, Error> {
debug_evt.try_clone().unwrap(),
#[cfg(feature = "guest_debug")]
vm_debug_evt.try_clone().unwrap(),
exit_evt.try_clone().unwrap(),
&seccomp_action,
hypervisor,
)
.map_err(Error::StartVmmThread)?;
let payload_present = toplevel.kernel.is_some() || toplevel.firmware.is_some();
let r: Result<(), Error> = (|| {
let payload_present = toplevel.kernel.is_some() || toplevel.firmware.is_some();
if payload_present {
let vm_params = toplevel.to_vm_params();
let vm_config = config::VmConfig::parse(vm_params).map_err(Error::ParsingConfig)?;
if payload_present {
let vm_params = toplevel.to_vm_params();
let vm_config = config::VmConfig::parse(vm_params).map_err(Error::ParsingConfig)?;
// Create and boot the VM based off the VM config we just built.
let sender = api_request_sender.clone();
vmm::api::vm_create(
api_evt.try_clone().unwrap(),
api_request_sender,
Arc::new(Mutex::new(vm_config)),
)
.map_err(Error::VmCreate)?;
vmm::api::vm_boot(api_evt.try_clone().unwrap(), sender).map_err(Error::VmBoot)?;
} else if let Some(restore_params) = toplevel.restore {
vmm::api::vm_restore(
api_evt.try_clone().unwrap(),
api_request_sender,
Arc::new(config::RestoreConfig::parse(&restore_params).map_err(Error::ParsingRestore)?),
)
.map_err(Error::VmRestore)?;
// Create and boot the VM based off the VM config we just built.
let sender = api_request_sender.clone();
vmm::api::vm_create(
api_evt.try_clone().unwrap(),
api_request_sender,
Arc::new(Mutex::new(vm_config)),
)
.map_err(Error::VmCreate)?;
vmm::api::vm_boot(api_evt.try_clone().unwrap(), sender).map_err(Error::VmBoot)?;
} else if let Some(restore_params) = toplevel.restore {
vmm::api::vm_restore(
api_evt.try_clone().unwrap(),
api_request_sender,
Arc::new(
config::RestoreConfig::parse(&restore_params).map_err(Error::ParsingRestore)?,
),
)
.map_err(Error::VmRestore)?;
}
Ok(())
})();
if r.is_err() {
if let Err(e) = exit_evt.write(1) {
warn!("writing to exit EventFd: {e}");
}
}
vmm_thread

10
vmm/src/lib.rs
View File

@ -288,6 +288,7 @@ pub fn start_vmm_thread(
#[cfg(feature = "guest_debug")] debug_path: Option<PathBuf>,
#[cfg(feature = "guest_debug")] debug_event: EventFd,
#[cfg(feature = "guest_debug")] vm_debug_event: EventFd,
exit_event: EventFd,
seccomp_action: &SeccompAction,
hypervisor: Arc<dyn hypervisor::Hypervisor>,
) -> Result<thread::JoinHandle<Result<()>>> {
@ -308,9 +309,8 @@ pub fn start_vmm_thread(
.map_err(Error::CreateSeccompFilter)?;
let vmm_seccomp_action = seccomp_action.clone();
let exit_evt = EventFd::new(EFD_NONBLOCK).map_err(Error::EventFdCreate)?;
let thread = {
let exit_evt = exit_evt.try_clone().map_err(Error::EventFdClone)?;
let exit_event = exit_event.try_clone().map_err(Error::EventFdClone)?;
thread::Builder::new()
.name("vmm".to_string())
.spawn(move || {
@ -328,7 +328,7 @@ pub fn start_vmm_thread(
vm_debug_event,
vmm_seccomp_action,
hypervisor,
exit_evt,
exit_event,
)?;
vmm.setup_signal_handler()?;
@ -349,7 +349,7 @@ pub fn start_vmm_thread(
http_api_event,
api_sender,
seccomp_action,
exit_evt,
exit_event,
hypervisor_type,
)?;
} else if let Some(http_fd) = http_fd {
@ -358,7 +358,7 @@ pub fn start_vmm_thread(
http_api_event,
api_sender,
seccomp_action,
exit_evt,
exit_event,
hypervisor_type,
)?;
}

8
vmm/src/vm.rs
View File

@ -314,10 +314,10 @@ impl VmState {
fn valid_transition(self, new_state: VmState) -> Result<()> {
match self {
VmState::Created => match new_state {
VmState::Created | VmState::Shutdown => {
Err(Error::InvalidStateTransition(self, new_state))
VmState::Created => Err(Error::InvalidStateTransition(self, new_state)),
VmState::Running | VmState::Paused | VmState::BreakPoint | VmState::Shutdown => {
Ok(())
}
VmState::Running | VmState::Paused | VmState::BreakPoint => Ok(()),
},
VmState::Running => match new_state {
@ -2694,7 +2694,7 @@ mod tests {
// Check the transitions from Created
assert!(state.valid_transition(VmState::Created).is_err());
assert!(state.valid_transition(VmState::Running).is_ok());
assert!(state.valid_transition(VmState::Shutdown).is_err());
assert!(state.valid_transition(VmState::Shutdown).is_ok());
assert!(state.valid_transition(VmState::Paused).is_ok());
assert!(state.valid_transition(VmState::BreakPoint).is_ok());
}