Add support for group-based permission checking in ext2

kernel/src/fs/ext2/inode.rs

@@ -18,7 +18,7 @@ use super::{
 };
 use crate::{
     fs::utils::{Extension, FallocMode, InodeMode, Metadata},
-    process::{Gid, Uid},
+    process::{posix_thread::AsPosixThread, Gid, Uid},
 };
 
 /// Max length of file name.
@@ -2075,11 +2075,12 @@ impl TryFrom<RawInode> for InodeDesc {
 impl InodeDesc {
     pub fn new(type_: InodeType, perm: FilePerm) -> Dirty<Self> {
         let now = now();
+        let credentials = current_thread!().as_posix_thread().unwrap().credentials();
         Dirty::new_dirty(Self {
             type_,
             perm,
-            uid: 0,
+            uid: credentials.fsuid().into(),
-            gid: 0,
+            gid: credentials.fsgid().into(),
             size: 0,
             atime: now,
             ctime: now,

kernel/src/fs/fs_resolver.rs

@@ -134,9 +134,6 @@ impl FsResolver {
         let parent = lookup_ctx
             .parent()
             .ok_or_else(|| Error::with_message(Errno::ENOENT, "parent not found"))?;
-        if !parent.mode()?.is_writable() {
-            return_errno_with_message!(Errno::EACCES, "file cannot be created");
-        }
 
         let tail_file_name = lookup_ctx.tail_file_name().unwrap();
         let new_dentry =

kernel/src/fs/inode_handle/dyn_cap.rs

@@ -8,14 +8,8 @@ use crate::{prelude::*, process::signal::Pollable};
 
 impl InodeHandle<Rights> {
     pub fn new(dentry: Dentry, access_mode: AccessMode, status_flags: StatusFlags) -> Result<Self> {
-        let inode_mode = dentry.inode().mode()?;
+        let inode = dentry.inode();
-        if access_mode.is_readable() && !inode_mode.is_readable() {
+        inode.check_permission(access_mode.into())?;
-            return_errno_with_message!(Errno::EACCES, "file is not readable");
-        }
-        if access_mode.is_writable() && !inode_mode.is_writable() {
-            return_errno_with_message!(Errno::EACCES, "file is not writable");
-        }
-
         Self::new_unchecked_access(dentry, access_mode, status_flags)
     }
 

kernel/src/fs/path/dentry.rs

@@ -15,7 +15,9 @@ use ostd::sync::RwMutexWriteGuard;
 use crate::{
     fs::{
         path::mount::MountNode,
-        utils::{FileSystem, Inode, InodeMode, InodeType, Metadata, MknodType, NAME_MAX},
+        utils::{
+            FileSystem, Inode, InodeMode, InodeType, Metadata, MknodType, Permission, NAME_MAX,
+        },
     },
     prelude::*,
     process::{Gid, Uid},
@@ -461,6 +463,13 @@ impl Dentry {
 
     /// Creates a new `Dentry` to represent the child directory of a file system.
     pub fn new_fs_child(&self, name: &str, type_: InodeType, mode: InodeMode) -> Result<Self> {
+        if self
+            .inode()
+            .check_permission(Permission::MAY_WRITE)
+            .is_err()
+        {
+            return_errno!(Errno::EACCES);
+        }
         let new_child_dentry = self.inner.create(name, type_, mode)?;
         Ok(Self::new(self.mount_node.clone(), new_child_dentry))
     }
@@ -474,7 +483,7 @@ impl Dentry {
         if self.type_() != InodeType::Dir {
             return_errno!(Errno::ENOTDIR);
         }
-        if !self.mode()?.is_executable() {
+        if self.inode().check_permission(Permission::MAY_EXEC).is_err() {
             return_errno!(Errno::EACCES);
         }
         if name.len() > NAME_MAX {

kernel/src/fs/utils/inode.rs

@@ -6,13 +6,14 @@ use core::{any::TypeId, time::Duration};
 
 use aster_rights::Full;
 use core2::io::{Error as IoError, ErrorKind as IoErrorKind, Result as IoResult, Write};
+use ostd::task::Task;
 
-use super::{DirentVisitor, FallocMode, FileSystem, IoctlCmd};
+use super::{AccessMode, DirentVisitor, FallocMode, FileSystem, IoctlCmd};
 use crate::{
     events::IoEvents,
     fs::device::{Device, DeviceType},
     prelude::*,
-    process::{signal::PollHandle, Gid, Uid},
+    process::{posix_thread::AsPosixThread, signal::PollHandle, Gid, Uid},
     time::clocks::RealTimeCoarseClock,
     vm::vmo::Vmo,
 };
@@ -80,6 +81,43 @@ impl From<DeviceType> for InodeType {
     }
 }
 
+bitflags! {
+    pub struct Permission: u16 {
+        // This implementation refers the implementation of linux
+        // https://elixir.bootlin.com/linux/v6.0.9/source/include/linux/fs.h#L95
+        const MAY_EXEC		= 0x0001;
+        const MAY_WRITE		= 0x0002;
+        const MAY_READ		= 0x0004;
+        const MAY_APPEND    = 0x0008;
+        const MAY_ACCESS	= 0x0010;
+        const MAY_OPEN		= 0x0020;
+        const MAY_CHDIR		= 0x0040;
+        const MAY_NOT_BLOCK	= 0x0080;
+    }
+}
+impl Permission {
+    pub fn may_read(&self) -> bool {
+        self.contains(Self::MAY_READ)
+    }
+
+    pub fn may_write(&self) -> bool {
+        self.contains(Self::MAY_WRITE)
+    }
+
+    pub fn may_exec(&self) -> bool {
+        self.contains(Self::MAY_EXEC)
+    }
+}
+impl From<AccessMode> for Permission {
+    fn from(access_mode: AccessMode) -> Permission {
+        match access_mode {
+            AccessMode::O_RDONLY => Permission::MAY_READ,
+            AccessMode::O_WRONLY => Permission::MAY_WRITE,
+            AccessMode::O_RDWR => Permission::MAY_READ | Permission::MAY_WRITE,
+        }
+    }
+}
+
 bitflags! {
     pub struct InodeMode: u16 {
         /// set-user-ID
@@ -110,18 +148,42 @@ bitflags! {
 }
 
 impl InodeMode {
-    pub fn is_readable(&self) -> bool {
+    pub fn is_owner_readable(&self) -> bool {
         self.contains(Self::S_IRUSR)
     }
 
-    pub fn is_writable(&self) -> bool {
+    pub fn is_owner_writable(&self) -> bool {
         self.contains(Self::S_IWUSR)
     }
 
-    pub fn is_executable(&self) -> bool {
+    pub fn is_owner_executable(&self) -> bool {
         self.contains(Self::S_IXUSR)
     }
 
+    pub fn is_group_readable(&self) -> bool {
+        self.contains(Self::S_IRGRP)
+    }
+
+    pub fn is_group_writable(&self) -> bool {
+        self.contains(Self::S_IWGRP)
+    }
+
+    pub fn is_group_executable(&self) -> bool {
+        self.contains(Self::S_IXGRP)
+    }
+
+    pub fn is_other_readable(&self) -> bool {
+        self.contains(Self::S_IROTH)
+    }
+
+    pub fn is_other_writable(&self) -> bool {
+        self.contains(Self::S_IWOTH)
+    }
+
+    pub fn is_other_executable(&self) -> bool {
+        self.contains(Self::S_IXOTH)
+    }
+
     pub fn has_sticky_bit(&self) -> bool {
         self.contains(Self::S_ISVTX)
     }
@@ -434,6 +496,47 @@ pub trait Inode: Any + Sync + Send {
     fn extension(&self) -> Option<&Extension> {
         None
     }
+
+    ///  Used to check for read/write/execute permissions on a file.
+    ///
+    /// Similar to Linux, using "fsuid" here allows setting filesystem permissions
+    /// without changing the "normal" uids for other tasks.
+    fn check_permission(&self, mut perm: Permission) -> Result<()> {
+        let creds = match Task::current() {
+            Some(task) => match task.as_posix_thread() {
+                Some(thread) => thread.credentials(),
+                None => return Ok(()),
+            },
+            None => return Ok(()),
+        };
+
+        perm =
+            perm.intersection(Permission::MAY_READ | Permission::MAY_WRITE | Permission::MAY_EXEC);
+        let mode = self.mode().unwrap();
+
+        if self.metadata().uid == creds.fsuid() {
+            if (perm.may_read() && !mode.is_owner_readable())
+                || (perm.may_write() && !mode.is_owner_writable())
+                || (perm.may_exec() && !mode.is_owner_executable())
+            {
+                return_errno_with_message!(Errno::EACCES, "owner permission check failed");
+            }
+        } else if self.metadata().gid == creds.fsgid() {
+            if (perm.may_read() && !mode.is_group_readable())
+                || (perm.may_write() && !mode.is_group_writable())
+                || (perm.may_exec() && !mode.is_group_executable())
+            {
+                return_errno_with_message!(Errno::EACCES, "group permission check failed");
+            }
+        } else if (perm.may_read() && !mode.is_other_readable())
+            || (perm.may_write() && !mode.is_other_writable())
+            || (perm.may_exec() && !mode.is_other_executable())
+        {
+            return_errno_with_message!(Errno::EACCES, "other permission check failed");
+        }
+
+        Ok(())
+    }
 }
 
 impl dyn Inode {

kernel/src/fs/utils/mod.rs

@@ -11,7 +11,7 @@ pub use falloc_mode::FallocMode;
 pub use file_creation_mask::FileCreationMask;
 pub use flock::{FlockItem, FlockList, FlockType};
 pub use fs::{FileSystem, FsFlags, SuperBlock};
-pub use inode::{Extension, Inode, InodeMode, InodeType, Metadata, MknodType};
+pub use inode::{Extension, Inode, InodeMode, InodeType, Metadata, MknodType, Permission};
 pub use ioctl::IoctlCmd;
 pub use page_cache::{PageCache, PageCacheBackend};
 pub use random_test::{generate_random_operation, new_fs_in_memory};

kernel/src/net/socket/unix/ns/path.rs

@@ -4,7 +4,7 @@ use crate::{
     fs::{
         fs_resolver::{split_path, FsPath},
         path::Dentry,
-        utils::{InodeMode, InodeType},
+        utils::{InodeMode, InodeType, Permission},
     },
     prelude::*,
     process::posix_thread::AsPosixThread,
@@ -19,7 +19,11 @@ pub fn lookup_socket_file(path: &str) -> Result<Dentry> {
         fs.lookup(&fs_path)?
     };
 
-    if !dentry.mode()?.is_readable() || !dentry.mode()?.is_writable() {
+    if dentry
+        .inode()
+        .check_permission(Permission::MAY_READ | Permission::MAY_WRITE)
+        .is_err()
+    {
         return_errno_with_message!(Errno::EACCES, "the socket file cannot be read or written")
     }
 

kernel/src/process/program_loader/mod.rs

@@ -12,6 +12,7 @@ use crate::{
     fs::{
         fs_resolver::{FsPath, FsResolver, AT_FDCWD},
         path::Dentry,
+        utils::Permission,
     },
     prelude::*,
 };
@@ -77,7 +78,11 @@ pub fn check_executable_file(dentry: &Dentry) -> Result<()> {
         return_errno_with_message!(Errno::EACCES, "the dentry is not a regular file");
     }
 
-    if !dentry.mode()?.is_executable() {
+    if dentry
+        .inode()
+        .check_permission(Permission::MAY_EXEC)
+        .is_err()
+    {
         return_errno_with_message!(Errno::EACCES, "the dentry is not executable");
     }
 

kernel/src/syscall/access.rs

@@ -5,7 +5,7 @@ use crate::{
     fs::{
         file_table::FileDesc,
         fs_resolver::{FsPath, AT_FDCWD},
-        utils::PATH_MAX,
+        utils::{Permission, PATH_MAX},
     },
     prelude::*,
 };
@@ -81,19 +81,19 @@ pub fn do_faccessat(
         return Ok(SyscallReturn::Return(0));
     }
 
-    let inode_mode = dentry.mode()?;
+    let inode = dentry.inode();
 
     // FIXME: The current implementation is dummy
-    if mode.contains(AccessMode::R_OK) && !inode_mode.is_readable() {
+    if mode.contains(AccessMode::R_OK) {
-        return_errno_with_message!(Errno::EACCES, "Read permission denied");
+        inode.check_permission(Permission::MAY_READ)?;
     }
 
-    if mode.contains(AccessMode::W_OK) && !inode_mode.is_writable() {
+    if mode.contains(AccessMode::W_OK) {
-        return_errno_with_message!(Errno::EACCES, "Write permission denied");
+        inode.check_permission(Permission::MAY_WRITE)?;
     }
 
-    if mode.contains(AccessMode::X_OK) && !inode_mode.is_executable() {
+    if mode.contains(AccessMode::X_OK) {
-        return_errno_with_message!(Errno::EACCES, "Execute permission denied");
+        inode.check_permission(Permission::MAY_EXEC)?;
     }
 
     Ok(SyscallReturn::Return(0))

test/syscall_test/Makefile

@@ -7,8 +7,6 @@
 # Please keep the list sorted by name.
 TESTS ?= \
 	access_test \
-	alarm_test \
-	chmod_test \
 	chown_test \
 	creat_test \
 	dup_test \

test/syscall_test/blocklists.exfat/access_test

@@ -1 +1,4 @@
 AccessTest.UsrReadWrite
+AccessTest.NoPerms
+AccessTest.UsrReadOnly
+AccessTest.UsrReadExec

test/syscall_test/blocklists.exfat/mkdir_test

@@ -1,2 +1,3 @@
 MkdirTest.HonorsUmask
 MkdirTest.HonorsUmask2
+MkdirTest.FailsOnDirWithoutWritePerms

test/syscall_test/blocklists.exfat/open_create_test

@@ -2,3 +2,4 @@ CreateTest.ChmodReadToWriteBetweenOpens_NoRandomSave
 CreateTest.ChmodWriteToReadBetweenOpens_NoRandomSave
 CreateTest.CreateWithReadFlagNotAllowedByMode_NoRandomSave
 CreateTest.CreateWithWriteFlagNotAllowedByMode_NoRandomSave
+CreateTest.CreateFailsOnDirWithoutWritePerms

test/syscall_test/blocklists/access_test

@@ -1,3 +0,0 @@
-AccessTest.NoPerms
-AccessTest.UsrReadOnly
-AccessTest.UsrReadExec

test/syscall_test/blocklists/mkdir_test

@@ -1 +0,0 @@
-MkdirTest.FailsOnDirWithoutWritePerms

test/syscall_test/blocklists/open_create_test

@@ -2,4 +2,3 @@ CreateTest.HonorsUmask_NoRandomSave
 CreateTest.CreatWithOTrunc
 CreateTest.CreatDirWithOTruncAndReadOnly
 CreateTest.CreateFailsOnUnpermittedDir
-CreateTest.CreateFailsOnDirWithoutWritePerms