1 files changed, 62 insertions, 0 deletions
diff --git a/src/utils/permissions.rs b/src/utils/permissions.rs
new file mode 100644
index 0000000..a3afe77
--- /dev/null
+++ b/src/utils/permissions.rs
@@ -0,0 +1,62 @@
+use std::fs::File;
+use std::io::BufRead;
+use libc::{F_OK, S_ISGID, S_ISUID, S_IXGRP, X_OK};
+use crate::disk::inode::InodeMode;
+
+pub(crate) fn get_groups(pid: u32) -> Vec<u32> {
+    let file = File::open(format!("/proc/{pid}/task/{pid}/status"))
+        .expect(format!("pid {pid} incorrect!").as_str());
+    for line in std::io::BufReader::new(file).lines() {
+        let line = line.unwrap();
+        if line.starts_with("Groups:") {
+            return line["Groups: ".len()..]
+                .split(' ')
+                .filter(|x| !x.trim().is_empty())
+                .map(|x| x.parse::<u32>().unwrap())
+                .collect();
+        }
+    }
+
+    Vec::new()
+}
+
+pub(crate) fn clear_suid_sgid(mut mode: InodeMode) -> InodeMode {
+    mode.0 &= !S_ISUID as u16;
+    if mode.0 & S_IXGRP as u16 != 0 {
+        mode.0 &= !S_ISGID as u16;
+    }
+    mode
+}
+
+pub(crate) fn check_access(
+    incoming_uid: u32,
+    incoming_gid: u32,
+    uid: u32,
+    gid: u32,
+    perm: InodeMode,
+    mut mask: i32,
+) -> bool {
+    if mask == F_OK {
+        return true;
+    }
+
+    let perm = i32::from(perm.0);
+    // root
+    if incoming_uid == 0 {
+        // 读写任何东西都是可以的, 执行只有 IXOTH/IXGRP/IXUSR 之一设置才可以
+        mask &= X_OK;
+        mask -= mask & (perm >> 6);
+        mask -= mask & (perm >> 3);
+        mask -= mask & perm;
+        return mask == 0;
+    }
+
+    if incoming_uid == uid {
+        mask -= mask & (perm >> 6);
+    } else if incoming_gid == gid {
+        mask -= mask & (perm >> 3);
+    } else {
+        mask -= mask & perm;
+    }
+    mask == 0
+}
+\ No newline at end of file