Merge "[rialto] Enable the host and service VM vsock connection" into main
diff --git a/authfs/src/fusefs.rs b/authfs/src/fusefs.rs
index bddf2c3..64b340a 100644
--- a/authfs/src/fusefs.rs
+++ b/authfs/src/fusefs.rs
@@ -993,8 +993,8 @@
     fn statfs(&self, _ctx: Context, _inode: Self::Inode) -> io::Result<libc::statvfs64> {
         let remote_stat = self.remote_fs_stats_reader.statfs()?;
 
-        // Safe because we are zero-initializing a struct with only POD fields. Not all fields
-        // matter to FUSE. See also:
+        // SAFETY: We are zero-initializing a struct with only POD fields. Not all fields matter to
+        // FUSE. See also:
         // https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/fuse/inode.c?h=v5.15#n460
         let mut st: libc::statvfs64 = unsafe { zeroed() };
 
diff --git a/compos/composd/src/fd_server_helper.rs b/compos/composd/src/fd_server_helper.rs
index 777ec27..24371b5 100644
--- a/compos/composd/src/fd_server_helper.rs
+++ b/compos/composd/src/fd_server_helper.rs
@@ -107,8 +107,9 @@
 
 fn create_pipe() -> Result<(File, File)> {
     let (raw_read, raw_write) = pipe2(OFlag::O_CLOEXEC)?;
-    // SAFETY: We are the sole owners of these fds as they were just created.
+    // SAFETY: We are the sole owner of raw_read and it is valid as it was just created.
     let read_fd = unsafe { File::from_raw_fd(raw_read) };
+    // SAFETY: We are the sole owner of raw_write and it is valid as it was just created.
     let write_fd = unsafe { File::from_raw_fd(raw_write) };
     Ok((read_fd, write_fd))
 }
diff --git a/compos/src/compsvc_main.rs b/compos/src/compsvc_main.rs
index 77e2daa..b0fc323 100644
--- a/compos/src/compsvc_main.rs
+++ b/compos/src/compsvc_main.rs
@@ -50,11 +50,11 @@
     debug!("compsvc is starting as a rpc service.");
     let param = ptr::null_mut();
     let mut service = compsvc::new_binder()?.as_binder();
+    let service = service.as_native_mut() as *mut AIBinder;
+    // SAFETY: We hold a strong pointer, so the raw pointer remains valid. The bindgen AIBinder
+    // is the same type as sys::AIBinder. It is safe for on_ready to be invoked at any time, with
+    // any parameter.
     unsafe {
-        // SAFETY: We hold a strong pointer, so the raw pointer remains valid. The bindgen AIBinder
-        // is the same type as sys::AIBinder.
-        let service = service.as_native_mut() as *mut AIBinder;
-        // SAFETY: It is safe for on_ready to be invoked at any time, with any parameter.
         AVmPayload_runVsockRpcServer(service, COMPOS_VSOCK_PORT, Some(on_ready), param);
     }
     Ok(())
diff --git a/encryptedstore/src/main.rs b/encryptedstore/src/main.rs
index 86fa6da..1a16f49 100644
--- a/encryptedstore/src/main.rs
+++ b/encryptedstore/src/main.rs
@@ -153,6 +153,9 @@
     let mountpoint = CString::new(mountpoint.as_os_str().as_bytes())?;
     let fstype = CString::new("ext4").unwrap();
 
+    // SAFETY: The source, target and filesystemtype are valid C strings. For ext4, data is expected
+    // to be a C string as well, which it is. None of these pointers are retained after mount
+    // returns.
     let ret = unsafe {
         libc::mount(
             source.as_ptr(),
diff --git a/libs/capabilities/src/caps.rs b/libs/capabilities/src/caps.rs
index 1f44a34..bc17fa8 100644
--- a/libs/capabilities/src/caps.rs
+++ b/libs/capabilities/src/caps.rs
@@ -26,8 +26,8 @@
 /// Removes inheritable capabilities set for this process.
 /// See: https://man7.org/linux/man-pages/man7/capabilities.7.html
 pub fn drop_inheritable_caps() -> Result<()> {
+    // SAFETY: we do not manipulate memory handled by libcap.
     unsafe {
-        // SAFETY: we do not manipulate memory handled by libcap.
         let caps = cap_get_proc();
         scopeguard::defer! {
             cap_free(caps as *mut std::os::raw::c_void);
@@ -49,8 +49,8 @@
 pub fn drop_bounding_set() -> Result<()> {
     let mut cap_id: cap_value_t = 0;
     while cap_id <= CAP_LAST_CAP.try_into().unwrap() {
+        // SAFETY: we do not manipulate memory handled by libcap.
         unsafe {
-            // SAFETY: we do not manipulate memory handled by libcap.
             if cap_drop_bound(cap_id) == -1 {
                 let e = Errno::last();
                 bail!("cap_drop_bound failed for {}: {:?}", cap_id, e);
diff --git a/microdroid_manager/src/dice.rs b/microdroid_manager/src/dice.rs
index bacefcd..8e078ea 100644
--- a/microdroid_manager/src/dice.rs
+++ b/microdroid_manager/src/dice.rs
@@ -78,7 +78,7 @@
         let mmap_size =
             file.read_u64::<NativeEndian>()
                 .map_err(|error| Error::new(error).context("Reading driver"))? as usize;
-        // It's safe to map the driver as the service will only create a single
+        // SAFETY: It's safe to map the driver as the service will only create a single
         // mapping per process.
         let mmap_addr = unsafe {
             let fd = file.as_raw_fd();
@@ -87,10 +87,10 @@
         if mmap_addr == MAP_FAILED {
             bail!("Failed to mmap {:?}", driver_path);
         }
-        // The slice is created for the region of memory that was just
+        let mmap_buf =
+        // SAFETY: The slice is created for the region of memory that was just
         // successfully mapped into the process address space so it will be
         // accessible and not referenced from anywhere else.
-        let mmap_buf =
             unsafe { slice::from_raw_parts((mmap_addr as *const u8).as_ref().unwrap(), mmap_size) };
         let bcc_handover =
             bcc_handover_parse(mmap_buf).map_err(|_| anyhow!("Failed to parse Bcc Handover"))?;
@@ -149,9 +149,9 @@
 impl Drop for DiceDriver<'_> {
     fn drop(&mut self) {
         if let &mut Self::Real { mmap_addr, mmap_size, .. } = self {
-            // All references to the mapped region have the same lifetime as self. Since self is
-            // being dropped, so are all the references to the mapped region meaning its safe to
-            // unmap.
+            // SAFETY: All references to the mapped region have the same lifetime as self. Since
+            // self is being dropped, so are all the references to the mapped region meaning it's
+            // safe to unmap.
             let ret = unsafe { munmap(mmap_addr, mmap_size) };
             if ret != 0 {
                 log::warn!("Failed to munmap ({})", ret);
diff --git a/microdroid_manager/src/main.rs b/microdroid_manager/src/main.rs
index 1cdcde1..319d2df 100644
--- a/microdroid_manager/src/main.rs
+++ b/microdroid_manager/src/main.rs
@@ -193,7 +193,7 @@
 
 /// Prepares a socket file descriptor for the vm payload service.
 ///
-/// # Safety requirement
+/// # Safety
 ///
 /// The caller must ensure that this function is the only place that claims ownership
 /// of the file descriptor and it is called only once.
@@ -267,6 +267,8 @@
     if Path::new(ENCRYPTEDSTORE_BACKING_DEVICE).exists() {
         let mountpoint = CString::new(ENCRYPTEDSTORE_MOUNTPOINT).unwrap();
 
+        // SAFETY: `mountpoint` is a valid C string. `syncfs` and `close` are safe for any parameter
+        // values.
         let ret = unsafe {
             let dirfd = libc::open(
                 mountpoint.as_ptr(),
@@ -856,19 +858,15 @@
         }
     };
 
+    // SAFETY: We are not accessing any resource of the parent process. This means we can't make any
+    // log calls inside the closure.
     unsafe {
-        // SAFETY: we are not accessing any resource of the parent process.
         command.pre_exec(|| {
-            info!("dropping capabilities before executing payload");
             // It is OK to continue with payload execution even if the calls below fail, since
             // whether process can use a capability is controlled by the SELinux. Dropping the
             // capabilities here is just another defense-in-depth layer.
-            if let Err(e) = cap::drop_inheritable_caps() {
-                error!("failed to drop inheritable capabilities: {:?}", e);
-            }
-            if let Err(e) = cap::drop_bounding_set() {
-                error!("failed to drop bounding set: {:?}", e);
-            }
+            let _ = cap::drop_inheritable_caps();
+            let _ = cap::drop_bounding_set();
             Ok(())
         });
     }
diff --git a/microdroid_manager/src/swap.rs b/microdroid_manager/src/swap.rs
index 2f4d176..c2b20ac 100644
--- a/microdroid_manager/src/swap.rs
+++ b/microdroid_manager/src/swap.rs
@@ -48,7 +48,7 @@
         .checked_mul(512)
         .ok_or_else(|| anyhow!("sysfs_size too large"))?;
 
-    // safe because we give a constant and known-valid sysconf parameter
+    // SAFETY: We give a constant and known-valid sysconf parameter.
     let pagesize = unsafe { libc::sysconf(libc::_SC_PAGE_SIZE) as u64 };
 
     let mut f = OpenOptions::new().read(false).write(true).open(format!("/dev/{}", dev))?;
@@ -75,7 +75,7 @@
 /// Simple "swapon", using libc:: wrapper.
 fn swapon(dev: &str) -> Result<()> {
     let swapon_arg = std::ffi::CString::new(format!("/dev/{}", dev))?;
-    // safe because we give a nul-terminated string and check the result
+    // SAFETY: We give a nul-terminated string and check the result.
     let res = unsafe { libc::swapon(swapon_arg.as_ptr(), 0) };
     if res != 0 {
         return Err(anyhow!("Failed to swapon: {}", Error::last_os_error()));
diff --git a/pvmfw/avb/tests/api_test.rs b/pvmfw/avb/tests/api_test.rs
index aa9ed36..3b78663 100644
--- a/pvmfw/avb/tests/api_test.rs
+++ b/pvmfw/avb/tests/api_test.rs
@@ -244,8 +244,8 @@
     let footer = extract_avb_footer(&kernel)?;
     assert!(footer.vbmeta_offset < total_len);
     let vbmeta_offset_addr = ptr::addr_of!(footer.vbmeta_offset) as *const u8;
-    // SAFETY: It is safe as both raw pointers `vbmeta_offset_addr` and `footer` are not null.
     let vbmeta_offset_start =
+    // SAFETY: It is safe as both raw pointers `vbmeta_offset_addr` and `footer` are not null.
         unsafe { vbmeta_offset_addr.offset_from(ptr::addr_of!(footer) as *const u8) };
     let footer_start = kernel.len() - size_of::<AvbFooter>();
     let vbmeta_offset_start = footer_start + usize::try_from(vbmeta_offset_start)?;
diff --git a/rialto/tests/test.rs b/rialto/tests/test.rs
index 31a0c55..4ad8eb8 100644
--- a/rialto/tests/test.rs
+++ b/rialto/tests/test.rs
@@ -158,6 +158,7 @@
 
     // SAFETY: These are new FDs with no previous owner.
     let reader = unsafe { File::from_raw_fd(reader_fd) };
+    // SAFETY: These are new FDs with no previous owner.
     let writer = unsafe { File::from_raw_fd(writer_fd) };
 
     thread::spawn(|| {
diff --git a/vmbase/example/tests/test.rs b/vmbase/example/tests/test.rs
index 3594523..2b6dfbc 100644
--- a/vmbase/example/tests/test.rs
+++ b/vmbase/example/tests/test.rs
@@ -143,6 +143,7 @@
 
     // SAFETY: These are new FDs with no previous owner.
     let reader = unsafe { File::from_raw_fd(reader_fd) };
+    // SAFETY: These are new FDs with no previous owner.
     let writer = unsafe { File::from_raw_fd(writer_fd) };
 
     Ok((reader, writer))
diff --git a/zipfuse/src/main.rs b/zipfuse/src/main.rs
index 20d6fd6..e8be42c 100644
--- a/zipfuse/src/main.rs
+++ b/zipfuse/src/main.rs
@@ -31,7 +31,7 @@
 use std::fs::{File, OpenOptions};
 use std::io;
 use std::io::Read;
-use std::mem::size_of;
+use std::mem::{size_of, MaybeUninit};
 use std::os::unix::io::AsRawFd;
 use std::path::Path;
 use std::path::PathBuf;
@@ -192,7 +192,8 @@
     #[allow(clippy::useless_conversion)]
     fn stat_from(&self, inode: Inode) -> io::Result<libc::stat64> {
         let inode_data = self.find_inode(inode)?;
-        let mut st = unsafe { std::mem::MaybeUninit::<libc::stat64>::zeroed().assume_init() };
+        // SAFETY: All fields of stat64 are valid for zero byte patterns.
+        let mut st = unsafe { MaybeUninit::<libc::stat64>::zeroed().assume_init() };
         st.st_dev = 0;
         st.st_nlink = if let Some(directory) = inode_data.get_directory() {
             (2 + directory.len() as libc::nlink_t).into()