Add SMACK support for ls utility

Author: ChrisDryden

Cargo.toml

@@ -65,6 +65,10 @@ feat_selinux = [
   "selinux",
   "stat/selinux",
 ]
+# "feat_smack" == enable support for SMACK Security Context (by using `--features feat_smack`)
+# NOTE:
+# * Running a uutils compiled with `feat_smack` requires a SMACK enabled Kernel at run time.
+feat_smack = ["ls/smack"]
 ##
 ## feature sets
 ## (common/core and Tier1) feature sets

src/uu/ls/Cargo.toml

@@ -60,3 +60,4 @@ harness = false
 
 [features]
 feat_selinux = ["selinux", "uucore/selinux"]
+smack = ["uucore/smack"]

src/uu/ls/src/ls.rs

@@ -365,7 +365,10 @@ pub struct Config {
     time_format_recent: String,        // Time format for recent dates
     time_format_older: Option<String>, // Time format for older dates (optional, if not present, time_format_recent is used)
     context: bool,
+    #[cfg(all(feature = "selinux", target_os = "linux"))]
     selinux_supported: bool,
+    #[cfg(all(feature = "smack", target_os = "linux"))]
+    smack_supported: bool,
     group_directories_first: bool,
     line_ending: LineEnding,
     dired: bool,
@@ -1157,16 +1160,10 @@ impl Config {
             time_format_recent,
             time_format_older,
             context,
-            selinux_supported: {
-                #[cfg(all(feature = "selinux", target_os = "linux"))]
-                {
-                    uucore::selinux::is_selinux_enabled()
-                }
-                #[cfg(not(all(feature = "selinux", target_os = "linux")))]
-                {
-                    false
-                }
-            },
+            #[cfg(all(feature = "selinux", target_os = "linux"))]
+            selinux_supported: uucore::selinux::is_selinux_enabled(),
+            #[cfg(all(feature = "smack", target_os = "linux"))]
+            smack_supported: uucore::smack::is_smack_enabled(),
             group_directories_first: options.get_flag(options::GROUP_DIRECTORIES_FIRST),
             line_ending: LineEnding::from_zero_flag(options.get_flag(options::ZERO)),
             dired,
@@ -3387,33 +3384,53 @@ fn get_security_context<'a>(
         }
     }
 
+    #[cfg(all(feature = "selinux", target_os = "linux"))]
     if config.selinux_supported {
-        #[cfg(all(feature = "selinux", target_os = "linux"))]
-        {
-            match selinux::SecurityContext::of_path(path, must_dereference, false) {
-                Err(_r) => {
-                    // TODO: show the actual reason why it failed
-                    show_warning!("failed to get security context of: {}", path.quote());
-                    return Cow::Borrowed(SUBSTITUTE_STRING);
-                }
-                Ok(None) => return Cow::Borrowed(SUBSTITUTE_STRING),
-                Ok(Some(context)) => {
-                    let context = context.as_bytes();
+        match selinux::SecurityContext::of_path(path, must_dereference, false) {
+            Err(_r) => {
+                // TODO: show the actual reason why it failed
+                show_warning!("failed to get security context of: {}", path.quote());
+                return Cow::Borrowed(SUBSTITUTE_STRING);
+            }
+            Ok(None) => return Cow::Borrowed(SUBSTITUTE_STRING),
+            Ok(Some(context)) => {
+                let context = context.as_bytes();
 
-                    let context = context.strip_suffix(&[0]).unwrap_or(context);
+                let context = context.strip_suffix(&[0]).unwrap_or(context);
 
-                    let res: String = String::from_utf8(context.to_vec()).unwrap_or_else(|e| {
-                        show_warning!(
-                            "getting security context of: {}: {}",
-                            path.quote(),
-                            e.to_string()
-                        );
+                let res: String = String::from_utf8(context.to_vec()).unwrap_or_else(|e| {
+                    show_warning!(
+                        "getting security context of: {}: {}",
+                        path.quote(),
+                        e.to_string()
+                    );
 
-                        String::from_utf8_lossy(context).to_string()
-                    });
+                    String::from_utf8_lossy(context).to_string()
+                });
 
-                    return Cow::Owned(res);
-                }
+                return Cow::Owned(res);
+            }
+        }
+    }
+
+    #[cfg(all(feature = "smack", target_os = "linux"))]
+    if config.smack_supported {
+        // For SMACK, use the path to get the label
+        // If must_dereference is true, we follow the symlink
+        let target_path = if must_dereference {
+            match std::fs::canonicalize(path) {
+                Ok(p) => p,
+                Err(_) => path.to_path_buf(),
+            }
+        } else {
+            path.to_path_buf()
+        };
+
+        match uucore::smack::get_smack_label_for_path(&target_path) {
+            Ok(label) => return Cow::Owned(label),
+            Err(_) => {
+                // No label or error getting label
+                return Cow::Borrowed(SUBSTITUTE_STRING);
             }
         }
     }

src/uucore/Cargo.toml

@@ -162,6 +162,7 @@ ranges = []
 ringbuffer = []
 safe-traversal = ["libc"]
 selinux = ["dep:selinux"]
+smack = ["xattr"]
 signals = []
 sum = [
   "digest",

src/uucore/locales/en-US.ftl

@@ -46,6 +46,12 @@ selinux-error-context-retrieval-failure = failed to retrieve the security contex
 selinux-error-context-set-failure = failed to set default file creation context to '{ $context }': { $error }
 selinux-error-context-conversion-failure = failed to set default file creation context to '{ $context }': { $error }
 
+# SMACK error messages
+smack-error-not-enabled = SMACK is not enabled on this system
+smack-error-label-retrieval-failure = failed to get SMACK label: { $error }
+smack-error-label-set-failure = failed to set SMACK label to '{ $context }': { $error }
+smack-error-no-label-set = no SMACK label set
+
 # Safe traversal error messages
 safe-traversal-error-path-contains-null = path contains null byte
 safe-traversal-error-open-failed = failed to open '{ $path }': { $source }

src/uucore/src/lib/features.rs

@@ -85,6 +85,8 @@ pub mod hardware;
 pub mod selinux;
 #[cfg(all(unix, not(target_os = "fuchsia"), feature = "signals"))]
 pub mod signals;
+#[cfg(all(target_os = "linux", feature = "smack"))]
+pub mod smack;
 #[cfg(feature = "feat_systemd_logind")]
 pub mod systemd_logind;
 #[cfg(all(

src/uucore/src/lib/features/smack.rs

@@ -0,0 +1,74 @@
+// This file is part of the uutils uucore package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+// spell-checker:ignore smackfs
+//! SMACK (Simplified Mandatory Access Control Kernel) support
+
+use std::io;
+use std::path::Path;
+
+use thiserror::Error;
+
+use crate::error::{UError, strip_errno};
+use crate::translate;
+
+#[derive(Debug, Error)]
+pub enum SmackError {
+    #[error("{}", translate!("smack-error-not-enabled"))]
+    SmackNotEnabled,
+
+    #[error("{}", translate!("smack-error-label-retrieval-failure", "error" => strip_errno(.0)))]
+    LabelRetrievalFailure(io::Error),
+
+    #[error("{}", translate!("smack-error-label-set-failure", "context" => .0.clone(), "error" => strip_errno(.1)))]
+    LabelSetFailure(String, io::Error),
+}
+
+impl UError for SmackError {
+    fn code(&self) -> i32 {
+        match self {
+            Self::SmackNotEnabled => 1,
+            Self::LabelRetrievalFailure(_) => 2,
+            Self::LabelSetFailure(_, _) => 3,
+        }
+    }
+}
+
+impl From<SmackError> for i32 {
+    fn from(error: SmackError) -> Self {
+        error.code()
+    }
+}
+
+/// Checks if SMACK is enabled by verifying smackfs is mounted.
+pub fn is_smack_enabled() -> bool {
+    Path::new("/sys/fs/smackfs").exists()
+}
+
+/// Gets the SMACK label for a filesystem path via xattr.
+pub fn get_smack_label_for_path(path: &Path) -> Result<String, SmackError> {
+    if !is_smack_enabled() {
+        return Err(SmackError::SmackNotEnabled);
+    }
+
+    match xattr::get(path, "security.SMACK64") {
+        Ok(Some(value)) => Ok(String::from_utf8_lossy(&value).trim().to_string()),
+        Ok(None) => Err(SmackError::LabelRetrievalFailure(io::Error::new(
+            io::ErrorKind::NotFound,
+            translate!("smack-error-no-label-set"),
+        ))),
+        Err(e) => Err(SmackError::LabelRetrievalFailure(e)),
+    }
+}
+
+/// Sets the SMACK label for a filesystem path via xattr.
+pub fn set_smack_label_for_path(path: &Path, label: &str) -> Result<(), SmackError> {
+    if !is_smack_enabled() {
+        return Err(SmackError::SmackNotEnabled);
+    }
+
+    xattr::set(path, "security.SMACK64", label.as_bytes())
+        .map_err(|e| SmackError::LabelSetFailure(label.to_string(), e))
+}

src/uucore/src/lib/lib.rs

@@ -125,6 +125,9 @@ pub use crate::features::fsxattr;
 #[cfg(all(target_os = "linux", feature = "selinux"))]
 pub use crate::features::selinux;
 
+#[cfg(all(target_os = "linux", feature = "smack"))]
+pub use crate::features::smack;
+
 //## core functions
 
 #[cfg(unix)]