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net_util: modify or provide safety comments

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Signed-off-by: Wei Liu <liuwe@microsoft.com>
This commit is contained in:
Wei Liu 2022-11-16 22:25:39 +00:00 committed by Liu Wei
parent c5bd8cabc4
commit 8a7f4b47cb
3 changed files with 36 additions and 20 deletions
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10
net_util/src/lib.rs
View File

@ -66,32 +66,34 @@ fn create_sockaddr(ip_addr: net::Ipv4Addr) -> net_gen::sockaddr {
let addr_in = net_gen::sockaddr_in {
sin_family: net_gen::AF_INET as u16,
sin_port: 0,
// SAFETY: ip_addr can be safely transmute to in_addr
sin_addr: unsafe { mem::transmute(ip_addr.octets()) },
__pad: [0; 8usize],
};
// SAFETY: addr_in can be safely transmute to sockaddr
unsafe { mem::transmute(addr_in) }
}
fn create_inet_socket() -> Result<net::UdpSocket> {
// This is safe since we check the return value.
// SAFETY: we check the return value.
let sock = unsafe { libc::socket(libc::AF_INET, libc::SOCK_DGRAM, 0) };
if sock < 0 {
return Err(Error::CreateSocket(IoError::last_os_error()));
}
// This is safe; nothing else will use or hold onto the raw sock fd.
// SAFETY: nothing else will use or hold onto the raw sock fd.
Ok(unsafe { net::UdpSocket::from_raw_fd(sock) })
}
fn create_unix_socket() -> Result<net::UdpSocket> {
// This is safe since we check the return value.
// SAFETY: we check the return value.
let sock = unsafe { libc::socket(libc::AF_UNIX, libc::SOCK_DGRAM, 0) };
if sock < 0 {
return Err(Error::CreateSocket(IoError::last_os_error()));
}
// This is safe; nothing else will use or hold onto the raw sock fd.
// SAFETY: nothing else will use or hold onto the raw sock fd.
Ok(unsafe { net::UdpSocket::from_raw_fd(sock) })
}

2
net_util/src/queue_pair.rs
View File

@ -83,6 +83,7 @@ impl TxVirtio {
}
let len = if !iovecs.is_empty() {
// SAFETY: FFI call with correct arguments
let result = unsafe {
libc::writev(
tap.as_raw_fd() as libc::c_int,
@ -217,6 +218,7 @@ impl RxVirtio {
}
let len = if !iovecs.is_empty() {
// SAFETY: FFI call with correct arguments
let result = unsafe {
libc::readv(
tap.as_raw_fd() as libc::c_int,

44
net_util/src/tap.rs
View File

@ -90,6 +90,7 @@ impl Tap {
pub fn open_named(if_name: &str, num_queue_pairs: usize, flags: Option<i32>) -> Result<Tap> {
let terminated_if_name = build_terminated_if_name(if_name)?;
// SAFETY: FFI call
let fd = unsafe {
// Open calls are safe because we give a constant null-terminated
// string and verify the result.
@ -102,13 +103,14 @@ impl Tap {
return Err(Error::OpenTun(IoError::last_os_error()));
}
// We just checked that the fd is valid.
// SAFETY: We just checked that the fd is valid.
let tuntap = unsafe { File::from_raw_fd(fd) };
// Let's validate some features before going any further.
// ioctl is safe since we call it with a valid tap fd and check the return
// value.
let mut features = 0;
// SAFETY: IOCTL with correct arguments
let ret = unsafe { ioctl_with_mut_ref(&tuntap, net_gen::TUNGETFEATURES(), &mut features) };
if ret < 0 {
return Err(Error::GetFeatures(IoError::last_os_error()));
@ -123,6 +125,7 @@ impl Tap {
// don't call as_mut on the same union field more than once, this block
// is safe.
let mut ifreq: net_gen::ifreq = Default::default();
// SAFETY: see the comment above.
unsafe {
let ifrn_name = ifreq.ifr_ifrn.ifrn_name.as_mut();
let name_slice = &mut ifrn_name[..terminated_if_name.len()];
@ -134,16 +137,16 @@ impl Tap {
}
}
// ioctl is safe since we call it with a valid tap fd and check the return
// SAFETY: ioctl is safe since we call it with a valid tap fd and check the return
// value.
let ret = unsafe { ioctl_with_mut_ref(&tuntap, net_gen::TUNSETIFF(), &mut ifreq) };
if ret < 0 {
return Err(Error::ConfigureTap(IoError::last_os_error()));
}
// SAFETY: only the name is accessed, and it's cloned out.
let mut if_name = unsafe { ifreq.ifr_ifrn.ifrn_name }.to_vec();
if_name.truncate(terminated_if_name.len() - 1);
// Safe since only the name is accessed, and it's cloned out.
Ok(Tap {
tap_file: tuntap,
if_name,
@ -158,6 +161,7 @@ impl Tap {
pub fn from_tap_fd(fd: RawFd, num_queue_pairs: usize) -> Result<Tap> {
// Ensure that the file is opened non-blocking, this is particularly
// needed when opened via the shell for macvtap.
// SAFETY: FFI call
let ret = unsafe {
let mut flags = libc::fcntl(fd, libc::F_GETFL);
flags |= libc::O_NONBLOCK;
@ -167,19 +171,22 @@ impl Tap {
return Err(Error::ConfigureTap(IoError::last_os_error()));
}
// SAFETY: fd is a tap fd
let tap_file = unsafe { File::from_raw_fd(fd) };
let mut ifreq: net_gen::ifreq = Default::default();
// Get current config including name
// SAFETY: IOCTL with correct arugments
let ret = unsafe { ioctl_with_mut_ref(&tap_file, net_gen::TUNGETIFF(), &mut ifreq) };
if ret < 0 {
return Err(Error::IoctlError(IoError::last_os_error()));
}
// We only access one field of the ifru union, hence this is safe.
// SAFETY: We only access one field of the ifru union
let if_name = unsafe { ifreq.ifr_ifrn.ifrn_name }.to_vec();
// Try and update flags. Depending on how the tap was created (macvtap
// or via open_named()) this might return -EEXIST so we just ignore that.
// SAFETY: access union fields
unsafe {
ifreq.ifr_ifru.ifru_flags =
(net_gen::IFF_TAP | net_gen::IFF_NO_PI | net_gen::IFF_VNET_HDR) as c_short;
@ -187,6 +194,7 @@ impl Tap {
ifreq.ifr_ifru.ifru_flags |= net_gen::IFF_MULTI_QUEUE as c_short;
}
}
// SAFETY: IOCTL with correct arguments
let ret = unsafe { ioctl_with_mut_ref(&tap_file, net_gen::TUNSETIFF(), &mut ifreq) };
if ret < 0 && IoError::last_os_error().raw_os_error().unwrap() != libc::EEXIST {
return Err(Error::ConfigureTap(IoError::last_os_error()));
@ -208,8 +216,8 @@ impl Tap {
ifreq.ifr_ifru.ifru_addr = addr;
// ioctl is safe. Called with a valid sock fd, and we check the return.
let ret =
// SAFETY: ioctl is safe. Called with a valid sock fd, and we check the return.
unsafe { ioctl_with_ref(&sock, net_gen::sockios::SIOCSIFADDR as c_ulong, &ifreq) };
if ret < 0 {
return Err(Error::IoctlError(IoError::last_os_error()));
@ -233,13 +241,13 @@ impl Tap {
let mut ifreq = self.get_ifreq();
// ioctl is safe. Called with a valid sock fd, and we check the return.
let ret =
// SAFETY: ioctl is safe. Called with a valid sock fd, and we check the return.
unsafe { ioctl_with_ref(&sock, net_gen::sockios::SIOCGIFHWADDR as c_ulong, &ifreq) };
if ret < 0 {
return Err(Error::IoctlError(IoError::last_os_error()));
}
// We only access one field of the ifru union, hence this is safe.
// SAFETY: We only access one field of the ifru union
unsafe {
let ifru_hwaddr = &mut ifreq.ifr_ifru.ifru_hwaddr;
for (i, v) in addr.get_bytes().iter().enumerate() {
@ -247,8 +255,8 @@ impl Tap {
}
}
// ioctl is safe. Called with a valid sock fd, and we check the return.
let ret =
// SAFETY: ioctl is safe. Called with a valid sock fd, and we check the return.
unsafe { ioctl_with_ref(&sock, net_gen::sockios::SIOCSIFHWADDR as c_ulong, &ifreq) };
if ret < 0 {
return Err(Error::IoctlError(IoError::last_os_error()));
@ -263,14 +271,14 @@ impl Tap {
let ifreq = self.get_ifreq();
// ioctl is safe. Called with a valid sock fd, and we check the return.
let ret =
// SAFETY: ioctl is safe. Called with a valid sock fd, and we check the return.
unsafe { ioctl_with_ref(&sock, net_gen::sockios::SIOCGIFHWADDR as c_ulong, &ifreq) };
if ret < 0 {
return Err(Error::IoctlError(IoError::last_os_error()));
}
// We only access one field of the ifru union, hence this is safe.
// SAFETY: We only access one field of the ifru union
let addr = unsafe {
MacAddr::from_bytes(&ifreq.ifr_ifru.ifru_hwaddr.sa_data[0..MAC_ADDR_LEN])
.map_err(Error::MacParsing)?
@ -287,8 +295,8 @@ impl Tap {
ifreq.ifr_ifru.ifru_addr = addr;
// ioctl is safe. Called with a valid sock fd, and we check the return.
let ret =
// SAFETY: ioctl is safe. Called with a valid sock fd, and we check the return.
unsafe { ioctl_with_ref(&sock, net_gen::sockios::SIOCSIFNETMASK as c_ulong, &ifreq) };
if ret < 0 {
return Err(Error::IoctlError(IoError::last_os_error()));
@ -302,12 +310,13 @@ impl Tap {
let ifreq = self.get_ifreq();
// ioctl is safe. Called with a valid sock fd, and we check the return.
// SAFETY: ioctl is safe. Called with a valid sock fd, and we check the return.
let ret = unsafe { ioctl_with_ref(&sock, net_gen::sockios::SIOCGIFMTU as c_ulong, &ifreq) };
if ret < 0 {
return Err(Error::IoctlError(IoError::last_os_error()));
}
// SAFETY: access a union field
let mtu = unsafe { ifreq.ifr_ifru.ifru_mtu };
Ok(mtu)
@ -319,7 +328,7 @@ impl Tap {
let mut ifreq = self.get_ifreq();
ifreq.ifr_ifru.ifru_mtu = mtu;
// ioctl is safe. Called with a valid sock fd, and we check the return.
// SAFETY: ioctl is safe. Called with a valid sock fd, and we check the return.
let ret = unsafe { ioctl_with_ref(&sock, net_gen::sockios::SIOCSIFMTU as c_ulong, &ifreq) };
if ret < 0 {
return Err(Error::IoctlError(IoError::last_os_error()));
@ -330,8 +339,8 @@ impl Tap {
/// Set the offload flags for the tap interface.
pub fn set_offload(&self, flags: c_uint) -> Result<()> {
// ioctl is safe. Called with a valid tap fd, and we check the return.
let ret =
// SAFETY: ioctl is safe. Called with a valid tap fd, and we check the return.
unsafe { ioctl_with_val(&self.tap_file, net_gen::TUNSETOFFLOAD(), flags as c_ulong) };
if ret < 0 {
return Err(Error::IoctlError(IoError::last_os_error()));
@ -347,12 +356,14 @@ impl Tap {
let mut ifreq = self.get_ifreq();
let ret =
// SAFETY: IOCTL with correct arguments
unsafe { ioctl_with_ref(&sock, net_gen::sockios::SIOCGIFFLAGS as c_ulong, &ifreq) };
if ret < 0 {
return Err(Error::IoctlError(IoError::last_os_error()));
}
// If TAP device is already up don't try and enable it
// SAFETY: access a union field
let ifru_flags = unsafe { ifreq.ifr_ifru.ifru_flags };
if ifru_flags & net_gen::net_device_flags_IFF_UP as i16
== net_gen::net_device_flags_IFF_UP as i16
@ -362,8 +373,8 @@ impl Tap {
ifreq.ifr_ifru.ifru_flags = net_gen::net_device_flags_IFF_UP as i16;
// ioctl is safe. Called with a valid sock fd, and we check the return.
let ret =
// SAFETY: ioctl is safe. Called with a valid sock fd, and we check the return.
unsafe { ioctl_with_ref(&sock, net_gen::sockios::SIOCSIFFLAGS as c_ulong, &ifreq) };
if ret < 0 {
return Err(Error::IoctlError(IoError::last_os_error()));
@ -374,7 +385,7 @@ impl Tap {
/// Set the size of the vnet hdr.
pub fn set_vnet_hdr_size(&self, size: c_int) -> Result<()> {
// ioctl is safe. Called with a valid tap fd, and we check the return.
// SAFETY: ioctl is safe. Called with a valid tap fd, and we check the return.
let ret = unsafe { ioctl_with_ref(&self.tap_file, net_gen::TUNSETVNETHDRSZ(), &size) };
if ret < 0 {
return Err(Error::IoctlError(IoError::last_os_error()));
@ -388,6 +399,7 @@ impl Tap {
// This sets the name of the interface, which is the only entry
// in a single-field union.
// SAFETY: access union fields and we're sure the copy is okay.
unsafe {
let ifrn_name = ifreq.ifr_ifrn.ifrn_name.as_mut();
let name_slice = &mut ifrn_name[..self.if_name.len()];