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Prevent parent directory from being opened without being preopened wasi
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Mark McCaskey committed May 22, 2019
1 parent 5ff9e74 commit b7abc44
Showing 1 changed file with 100 additions and 80 deletions.
180 changes: 100 additions & 80 deletions lib/wasi/src/syscalls/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1463,97 +1463,117 @@ pub fn path_open(
"Looking for file {} in directory {:#?}",
file_name, cumulative_path
);

cumulative_path.push(file_name);
let file_path = cumulative_path;

let out_fd = if let Kind::Dir { entries, .. } = &mut state.fs.inodes[cur_dir_inode].kind {
if let Some(child) = entries.get(file_name).cloned() {
let child_inode_val = &state.fs.inodes[child];
// early return based on flags
if o_flags & __WASI_O_EXCL != 0 {
return __WASI_EEXIST;
}
if o_flags & __WASI_O_DIRECTORY != 0 {
match &child_inode_val.kind {
Kind::Dir { .. } => (),
Kind::Symlink { .. } => {
unimplemented!("Symlinks not yet supported in path_open")
}
_ => return __WASI_ENOTDIR,
}
let out_fd = if let Kind::Dir {
entries, parent, ..
} = &mut state.fs.inodes[cur_dir_inode].kind
{
// short circuit logic if attempting to get parent
if file_name == ".." {
if let Some(p) = parent {
let parent_inode = *p;
wasi_try!(state.fs.create_fd(
fs_rights_base,
fs_rights_inheriting,
fs_flags,
parent_inode
))
} else {
return __WASI_EACCES;
}
// do logic on child
wasi_try!(state
.fs
.create_fd(fs_rights_base, fs_rights_inheriting, fs_flags, child))
} else {
debug!("Attempting to load file from host system");
let file_metadata = file_path.metadata();
// if entry does not exist in parent directory, try to lazily
// load it; possibly creating or truncating it if flags set
let kind = if file_metadata.is_ok() && file_metadata.unwrap().is_dir() {
// special dir logic
Kind::Dir {
parent: Some(cur_dir_inode),
path: file_path.clone(),
entries: Default::default(),
if let Some(child) = entries.get(file_name).cloned() {
let child_inode_val = &state.fs.inodes[child];
// early return based on flags
if o_flags & __WASI_O_EXCL != 0 {
return __WASI_EEXIST;
}
if o_flags & __WASI_O_DIRECTORY != 0 {
match &child_inode_val.kind {
Kind::Dir { .. } => (),
Kind::Symlink { .. } => {
unimplemented!("Symlinks not yet supported in path_open")
}
_ => return __WASI_ENOTDIR,
}
}
// do logic on child
wasi_try!(state
.fs
.create_fd(fs_rights_base, fs_rights_inheriting, fs_flags, child))
} else {
// file is not a dir
let real_opened_file = {
let mut open_options = std::fs::OpenOptions::new();
let open_options = open_options.read(true);
let open_options = if fs_rights_base & __WASI_RIGHT_FD_WRITE != 0 {
open_options.write(true)
} else {
open_options
};
let open_options = if o_flags & __WASI_O_CREAT != 0 {
debug!(
"File {:?} may be created when opened if it does not exist",
&file_path
);
open_options.create(true)
} else {
open_options
};
let open_options = if o_flags & __WASI_O_TRUNC != 0 {
debug!("File {:?} will be truncated when opened", &file_path);
open_options.truncate(true)
} else {
open_options
};
debug!("Opening host file {:?}", &file_path);
let real_open_file =
wasi_try!(open_options.open(&file_path).map_err(|_| __WASI_EIO));
debug!("Attempting to load file from host system");

let file_metadata = file_path.metadata();
// if entry does not exist in parent directory, try to lazily
// load it; possibly creating or truncating it if flags set
let kind = if file_metadata.is_ok() && file_metadata.unwrap().is_dir() {
// special dir logic
Kind::Dir {
parent: Some(cur_dir_inode),
path: file_path.clone(),
entries: Default::default(),
}
} else {
// file is not a dir
let real_opened_file = {
let mut open_options = std::fs::OpenOptions::new();
let open_options = open_options.read(true);
let open_options = if fs_rights_base & __WASI_RIGHT_FD_WRITE != 0 {
open_options.write(true)
} else {
open_options
};
let open_options = if o_flags & __WASI_O_CREAT != 0 {
debug!(
"File {:?} may be created when opened if it does not exist",
&file_path
);
open_options.create(true)
} else {
open_options
};
let open_options = if o_flags & __WASI_O_TRUNC != 0 {
debug!("File {:?} will be truncated when opened", &file_path);
open_options.truncate(true)
} else {
open_options
};
debug!("Opening host file {:?}", &file_path);
let real_open_file =
wasi_try!(open_options.open(&file_path).map_err(|_| __WASI_EIO));

real_open_file
real_open_file
};
Kind::File {
handle: WasiFile::HostFile(real_opened_file),
}
};
Kind::File {
handle: WasiFile::HostFile(real_opened_file),
}
};

// record lazily loaded or newly created fd
let new_inode = state.fs.inodes.insert(InodeVal {
stat: wasi_try!(get_stat_for_kind(&kind).ok_or(__WASI_EIO)),
is_preopened: false,
name: file_name.clone(),
kind,
});

// reborrow to insert entry
if let Kind::Dir { entries, .. } = &mut state.fs.inodes[working_dir.inode].kind {
entries.insert(file_name.clone(), new_inode);
// record lazily loaded or newly created fd
let new_inode = state.fs.inodes.insert(InodeVal {
stat: wasi_try!(get_stat_for_kind(&kind).ok_or(__WASI_EIO)),
is_preopened: false,
name: file_name.clone(),
kind,
});

// reborrow to insert entry
if let Kind::Dir { entries, .. } = &mut state.fs.inodes[working_dir.inode].kind {
entries.insert(file_name.clone(), new_inode);
}
let new_fd = wasi_try!(state.fs.create_fd(
fs_rights_base,
fs_rights_inheriting,
fs_flags,
new_inode,
));

new_fd
}
let new_fd = wasi_try!(state.fs.create_fd(
fs_rights_base,
fs_rights_inheriting,
fs_flags,
new_inode,
));

new_fd
}
} else {
// working_dir did not match on Kind::Dir
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