mkdir: added acl permissions inheritance for subdirectories (#…

…6676)

Mostly for linux for now

src/uu/mkdir/Cargo.toml

@@ -18,7 +18,8 @@ path = "src/mkdir.rs"
 
 [dependencies]
 clap = { workspace = true }
-uucore = { workspace = true, features = ["fs", "mode"] }
+uucore = { workspace = true, features = ["fs", "mode", "fsxattr"] }
+
 
 [[bin]]
 name = "mkdir"

src/uu/mkdir/src/mkdir.rs

@@ -164,20 +164,14 @@ pub fn mkdir(path: &Path, recursive: bool, mode: u32, verbose: bool) -> UResult<
     // std::fs::create_dir("foo/."); fails in pure Rust
     let path_buf = dir_strip_dot_for_creation(path);
     let path = path_buf.as_path();
-
-    if create_dir(path, recursive, verbose, false)? {
-        chmod(path, mode)?;
-    }
-    Ok(())
+    create_dir(path, recursive, verbose, false, mode)
 }
 
 #[cfg(any(unix, target_os = "redox"))]
 fn chmod(path: &Path, mode: u32) -> UResult<()> {
     use std::fs::{set_permissions, Permissions};
     use std::os::unix::fs::PermissionsExt;
-
     let mode = Permissions::from_mode(mode);
-
     set_permissions(path, mode)
         .map_err_context(|| format!("cannot set permissions {}", path.quote()))
 }
@@ -191,27 +185,33 @@ fn chmod(_path: &Path, _mode: u32) -> UResult<()> {
 // Return true if the directory at `path` has been created by this call.
 // `is_parent` argument is not used on windows
 #[allow(unused_variables)]
-fn create_dir(path: &Path, recursive: bool, verbose: bool, is_parent: bool) -> UResult<bool> {
-    if path.exists() && !recursive {
+fn create_dir(
+    path: &Path,
+    recursive: bool,
+    verbose: bool,
+    is_parent: bool,
+    mode: u32,
+) -> UResult<()> {
+    let path_exists = path.exists();
+    if path_exists && !recursive {
         return Err(USimpleError::new(
             1,
             format!("{}: File exists", path.display()),
         ));
     }
     if path == Path::new("") {
-        return Ok(false);
+        return Ok(());
     }
 
     if recursive {
         match path.parent() {
-            Some(p) => {
-                create_dir(p, recursive, verbose, true)?;
-            }
+            Some(p) => create_dir(p, recursive, verbose, true, mode)?,
             None => {
                 USimpleError::new(1, "failed to create whole tree");
             }
         }
     }
+
     match std::fs::create_dir(path) {
         Ok(()) => {
             if verbose {
@@ -221,15 +221,35 @@ fn create_dir(path: &Path, recursive: bool, verbose: bool, is_parent: bool) -> U
                     path.quote()
                 );
             }
-            #[cfg(not(windows))]
-            if is_parent {
-                // directories created by -p have permission bits set to '=rwx,u+wx',
-                // which is umask modified by 'u+wx'
-                chmod(path, (!mode::get_umask() & 0o0777) | 0o0300)?;
-            }
-            Ok(true)
+
+            #[cfg(all(unix, target_os = "linux"))]
+            let new_mode = if path_exists {
+                mode
+            } else {
+                // TODO: Make this macos and freebsd compatible by creating a function to get permission bits from
+                // acl in extended attributes
+                let acl_perm_bits = uucore::fsxattr::get_acl_perm_bits_from_xattr(path);
+
+                if is_parent {
+                    (!mode::get_umask() & 0o777) | 0o300 | acl_perm_bits
+                } else {
+                    mode | acl_perm_bits
+                }
+            };
+            #[cfg(all(unix, not(target_os = "linux")))]
+            let new_mode = if is_parent {
+                (!mode::get_umask() & 0o777) | 0o300
+            } else {
+                mode
+            };
+            #[cfg(windows)]
+            let new_mode = mode;
+
+            chmod(path, new_mode)?;
+            Ok(())
         }
-        Err(_) if path.is_dir() => Ok(false),
+
+        Err(_) if path.is_dir() => Ok(()),
         Err(e) => Err(e.into()),
     }
 }

src/uucore/src/lib/features/fsxattr.rs

@@ -3,7 +3,7 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
-// spell-checker:ignore getxattr
+// spell-checker:ignore getxattr posix_acl_default
 
 //! Set of functions to manage xattr on files and dirs
 use std::collections::HashMap;
@@ -88,6 +88,58 @@ pub fn has_acl<P: AsRef<Path>>(file: P) -> bool {
     }
 }
 
+/// Returns the permissions bits of a file or directory which has Access Control List (ACL) entries based on its
+/// extended attributes (Only works for linux)
+///
+/// # Arguments
+///
+/// * `source` - A reference to the path of the file.
+///
+/// # Returns
+///
+/// `u32`  the perm bits of a file having extended attributes of type 'system.posix_acl_default' with permissions
+/// otherwise returns a 0 if perm bits are 0 or the file has no extended attributes
+pub fn get_acl_perm_bits_from_xattr<P: AsRef<Path>>(source: P) -> u32 {
+    // TODO: Modify this to work on non linux unix systems.
+
+    // Only default acl entries get inherited by objects under the path i.e. if child directories
+    // will have their permissions modified.
+    if let Ok(entries) = retrieve_xattrs(source) {
+        let mut perm: u32 = 0;
+        if let Some(value) = entries.get(&OsString::from("system.posix_acl_default")) {
+            // value is xattr byte vector
+            // value follows a starts with a 4 byte header, and then has posix_acl_entries, each
+            // posix_acl_entry is separated by a u32 sequence i.e. 0xFFFFFFFF
+            //
+            // struct posix_acl_entries {
+            // e_tag: u16
+            //  e_perm: u16
+            //  e_id: u32
+            // }
+            //
+            // Reference: `https://github.com/torvalds/linux/blob/master/include/uapi/linux/posix_acl_xattr.h`
+            //
+            // The value of the header is 0x0002, so we skip the first four bytes of the value and
+            // process the rest
+
+            let acl_entries = value
+                .split_at(3)
+                .1
+                .iter()
+                .filter(|&x| *x != 255)
+                .copied()
+                .collect::<Vec<u8>>();
+
+            for entry in acl_entries.chunks_exact(4) {
+                // Third byte and fourth byte will be the perm bits
+                perm = (perm << 3) | entry[2] as u32 | entry[3] as u32;
+            }
+            return perm;
+        }
+    }
+    0
+}
+
 // FIXME: 3 tests failed on OpenBSD
 #[cfg(not(target_os = "openbsd"))]
 #[cfg(test)]
@@ -138,6 +190,52 @@ mod tests {
         );
     }
 
+    #[test]
+    #[cfg(target_os = "linux")]
+    fn test_get_perm_bits_from_xattrs() {
+        let temp_dir = tempdir().unwrap();
+        let source_path = temp_dir.path().join("source_dir");
+
+        std::fs::create_dir(&source_path).unwrap();
+
+        let test_attr = "system.posix_acl_default";
+        // posix_acl entries are in the form of
+        // struct posix_acl_entry{
+        //  tag: u16,
+        //  perm: u16,
+        //  id: u32,
+        // }
+        // the fields are serialized in little endian.
+        // The entries are preceded by a header of value of 0x0002
+        // Reference: `<https://github.com/torvalds/linux/blob/master/include/uapi/linux/posix_acl_xattr.h>`
+        // The id is undefined i.e. -1 which in u32 is 0xFFFFFFFF and tag and perm bits as given in the
+        // header file.
+        // Reference: `<https://github.com/torvalds/linux/blob/master/include/uapi/linux/posix_acl.h>`
+        //
+        //
+        // There is a bindgen bug which generates the ACL_OTHER constant whose value is 0x20 into 32.
+        // which when the bug is fixed will need to be changed back to 20 from 32 in the vec 'test_value'.
+        //
+        // Reference `<https://github.com/rust-lang/rust-bindgen/issues/2926>`
+        //
+        // The test_value vector is the header 0x0002 followed by tag and permissions for user_obj , tag
+        // and permissions and for group_obj and finally the tag and permissions for ACL_OTHER. Each
+        // entry has undefined id as mentioned above.
+        //
+        //
+
+        let test_value = vec![
+            2, 0, 0, 0, 1, 0, 7, 0, 255, 255, 255, 255, 4, 0, 0, 0, 255, 255, 255, 255, 32, 0, 0,
+            0, 255, 255, 255, 255,
+        ];
+
+        xattr::set(&source_path, test_attr, test_value.as_slice()).unwrap();
+
+        let perm_bits = get_acl_perm_bits_from_xattr(source_path);
+
+        assert_eq!(0o700, perm_bits);
+    }
+
     #[test]
     fn test_file_has_acl() {
         let temp_dir = tempdir().unwrap();

tests/by-util/test_mkdir.rs

@@ -228,6 +228,61 @@ fn test_recursive_reporting() {
         .stdout_contains("created directory 'test_dir/../test_dir_a/../test_dir_b'");
 }
 
+#[test]
+// Windows don't have acl entries
+// TODO Enable and modify this for macos when xattr processing for macos is added.
+// TODO Enable and modify this for freebsd when xattr processing for freebsd is enabled.
+#[cfg(target_os = "linux")]
+fn test_mkdir_acl() {
+    use std::{collections::HashMap, ffi::OsString};
+
+    let (at, mut ucmd) = at_and_ucmd!();
+
+    at.mkdir("a");
+
+    let mut map: HashMap<OsString, Vec<u8>> = HashMap::new();
+    // posix_acl entries are in the form of
+    // struct posix_acl_entry{
+    //  tag: u16,
+    //  perm: u16,
+    //  id: u32,
+    // }
+    // the fields are serialized in little endian.
+    // The entries are preceded by a header of value of 0x0002
+    // Reference: `<https://github.com/torvalds/linux/blob/master/include/uapi/linux/posix_acl_xattr.h>`
+    // The id is undefined i.e. -1 which in u32 is 0xFFFFFFFF and tag and perm bits as given in the
+    // header file.
+    // Reference: `<https://github.com/torvalds/linux/blob/master/include/uapi/linux/posix_acl.h>`
+    //
+    //
+    // There is a bindgen bug which generates the ACL_OTHER constant whose value is 0x20 into 32.
+    // which when the bug is fixed will need to be changed back to 20 from 32 in the vec 'xattr_val'.
+    //
+    // Reference `<https://github.com/rust-lang/rust-bindgen/issues/2926>`
+    //
+    // The xattr_val vector is the header 0x0002 followed by tag and permissions for user_obj , tag
+    // and permissions and for group_obj and finally the tag and permissions for ACL_OTHER. Each
+    // entry has undefined id as mentioned above.
+    //
+    //
+
+    let xattr_val: Vec<u8> = vec![
+        2, 0, 0, 0, 1, 0, 7, 0, 255, 255, 255, 255, 4, 0, 7, 0, 255, 255, 255, 255, 32, 0, 5, 0,
+        255, 255, 255, 255,
+    ];
+
+    map.insert(OsString::from("system.posix_acl_default"), xattr_val);
+
+    uucore::fsxattr::apply_xattrs(at.plus("a"), map).unwrap();
+
+    ucmd.arg("-p").arg("a/b").umask(0x077).succeeds();
+
+    let perms = at.metadata("a/b").permissions().mode();
+
+    // 0x770 would be user:rwx,group:rwx permissions
+    assert_eq!(perms, 16893);
+}
+
 #[test]
 fn test_mkdir_trailing_dot() {
     new_ucmd!().arg("-p").arg("-v").arg("test_dir").succeeds();