Kernel: Fix directory permissions

We did not care about X bit in directories and instead used only the
R bit for search/read.

kernel/include/kernel/OpenFileDescriptorSet.h

@@ -34,6 +34,8 @@ namespace Kernel
 		BAN::ErrorOr<off_t> tell(int) const;
 
 		BAN::ErrorOr<void> fstat(int fd, struct stat*) const;
+		BAN::ErrorOr<void> fstatat(int fd, BAN::StringView path, struct stat* buf, int flag);
+		BAN::ErrorOr<void> stat(BAN::StringView absolute_path, struct stat* buf, int flag);
 
 		BAN::ErrorOr<void> close(int);
 		void close_all();

kernel/include/kernel/Process.h

@@ -106,6 +106,8 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_tell(int fd);
 
 		BAN::ErrorOr<long> sys_fstat(int fd, struct stat*);
+		BAN::ErrorOr<long> sys_fstatat(int fd, const char* path, struct stat* buf, int flag);
+		BAN::ErrorOr<long> sys_stat(const char* path, struct stat* buf, int flag);
 
 		BAN::ErrorOr<void> mount(BAN::StringView source, BAN::StringView target);
 

kernel/kernel/FS/Inode.cpp

@@ -38,7 +38,7 @@ namespace Kernel
 			}
 		}
 
-		if (flags & O_EXEC)
+		if (flags & (O_EXEC | O_SEARCH))
 		{
 			if (mode().mode & S_IXOTH)
 			{ }

kernel/kernel/FS/VirtualFileSystem.cpp

@@ -133,7 +133,7 @@ namespace Kernel
 			}
 			else
 			{
-				if (!inode->can_access(credentials, O_RDONLY))
+				if (!inode->can_access(credentials, O_SEARCH))
 					return BAN::Error::from_errno(EACCES);
 
 				inode = TRY(inode->directory_find_inode(path_part));
@@ -152,7 +152,7 @@ namespace Kernel
 				auto target = TRY(inode->link_target());
 				if (target.empty())
 					return BAN::Error::from_errno(ENOENT);
-				
+
 				if (target.front() == '/')
 				{
 					inode = root_inode();

kernel/kernel/OpenFileDescriptorSet.cpp

@@ -179,11 +179,8 @@ namespace Kernel
 		return m_open_files[fd]->offset;
 	}
 
-	BAN::ErrorOr<void> OpenFileDescriptorSet::fstat(int fd, struct stat* out) const
+	static void read_stat_from_inode(BAN::RefPtr<Inode> inode, struct stat* out)
 	{
-		TRY(validate_fd(fd));
-
-		auto inode = m_open_files[fd]->inode;
 		out->st_dev		= inode->dev();
 		out->st_ino		= inode->ino();
 		out->st_mode	= inode->mode().mode;
@@ -197,7 +194,42 @@ namespace Kernel
 		out->st_ctim	= inode->ctime();
 		out->st_blksize	= inode->blksize();
 		out->st_blocks	= inode->blocks();
+	}
 
+	BAN::ErrorOr<void> OpenFileDescriptorSet::fstat(int fd, struct stat* out) const
+	{
+		TRY(validate_fd(fd));
+		read_stat_from_inode(m_open_files[fd]->inode, out);
+		return {};
+	}
+
+	BAN::ErrorOr<void> OpenFileDescriptorSet::fstatat(int fd, BAN::StringView path, struct stat* out, int flag)
+	{
+		if (flag & ~AT_SYMLINK_NOFOLLOW)
+			return BAN::Error::from_errno(EINVAL);
+		if (flag == AT_SYMLINK_NOFOLLOW)
+			flag = O_NOFOLLOW;
+
+		BAN::String absolute_path;
+		TRY(absolute_path.append(TRY(path_of(fd))));
+		TRY(absolute_path.push_back('/'));
+		TRY(absolute_path.append(path));
+
+		// FIXME: handle O_SEARCH in fd
+		auto file = TRY(VirtualFileSystem::get().file_from_absolute_path(m_credentials, absolute_path, flag));
+		read_stat_from_inode(file.inode, out);
+
+		return {};
+	}
+
+	BAN::ErrorOr<void> OpenFileDescriptorSet::stat(BAN::StringView absolute_path, struct stat* out, int flag)
+	{
+		if (flag & ~AT_SYMLINK_NOFOLLOW)
+			return BAN::Error::from_errno(EINVAL);
+		if (flag == AT_SYMLINK_NOFOLLOW)
+			flag = O_NOFOLLOW;
+		auto file = TRY(VirtualFileSystem::get().file_from_absolute_path(m_credentials, absolute_path, flag));
+		read_stat_from_inode(file.inode, out);
 		return {};
 	}
 
@@ -256,6 +288,8 @@ namespace Kernel
 	{
 		TRY(validate_fd(fd));
 		auto& open_file = m_open_files[fd];
+		if (!(open_file->flags & O_RDONLY))
+			return BAN::Error::from_errno(EACCES);
 		TRY(open_file->inode->directory_read_next_entries(open_file->offset, list, list_size));
 		open_file->offset++;
 		return {};

kernel/kernel/Process.cpp

@@ -630,6 +630,8 @@ namespace Kernel
 	{
 		LockGuard _(m_lock);
 
+		// FIXME: handle O_SEARCH in fd
+
 		BAN::String absolute_path;
 		TRY(absolute_path.append(TRY(m_open_file_descriptors.path_of(fd))));
 		TRY(absolute_path.push_back('/'));
@@ -737,6 +739,20 @@ namespace Kernel
 		return 0;
 	}
 
+	BAN::ErrorOr<long> Process::sys_fstatat(int fd, const char* path, struct stat* buf, int flag)
+	{
+		LockGuard _(m_lock);
+		TRY(m_open_file_descriptors.fstatat(fd, path, buf, flag));
+		return 0;
+	}
+
+	BAN::ErrorOr<long> Process::sys_stat(const char* path, struct stat* buf, int flag)
+	{
+		LockGuard _(m_lock);
+		TRY(m_open_file_descriptors.stat(TRY(absolute_path_of(path)), buf, flag));
+		return 0;
+	}
+
 	BAN::ErrorOr<long> Process::sys_read_dir_entries(int fd, DirectoryEntryList* list, size_t list_size)
 	{
 		LockGuard _(m_lock);

kernel/kernel/Syscall.cpp

@@ -185,6 +185,12 @@ namespace Kernel
 		case SYS_NANOSLEEP:
 			ret = Process::current().sys_nanosleep((const timespec*)arg1, (timespec*)arg2);
 			break;
+		case SYS_FSTATAT:
+			ret = Process::current().sys_fstatat((int)arg1, (const char*)arg2, (struct stat*)arg3, (int)arg4);
+			break;
+		case SYS_STAT:
+			ret = Process::current().sys_stat((const char*)arg1, (struct stat*)arg2, (int)arg3);
+			break;
 		default:
 			dwarnln("Unknown syscall {}", syscall);
 			break;

libc/dirent.cpp

@@ -58,7 +58,7 @@ DIR* fdopendir(int fd)
 
 DIR* opendir(const char* dirname)
 {
-	int fd = open(dirname, O_SEARCH);
+	int fd = open(dirname, O_RDONLY);
 	if (fd == -1)
 		return nullptr;
 	return fdopendir(fd);

libc/include/sys/syscall.h

@@ -52,6 +52,8 @@ __BEGIN_DECLS
 #define SYS_SET_PGID 45
 #define SYS_FCNTL 46
 #define SYS_NANOSLEEP 47
+#define SYS_FSTATAT 48
+#define SYS_STAT 49 // stat/lstat
 
 __END_DECLS
 

libc/sys/stat.cpp

@@ -11,38 +11,15 @@ int fstat(int fildes, struct stat* buf)
 
 int fstatat(int fd, const char* __restrict path, struct stat* __restrict buf, int flag)
 {
-	if (flag == AT_SYMLINK_NOFOLLOW)
-		flag = O_NOFOLLOW;
-	else if (flag)
-	{
-		errno = EINVAL;
-		return -1;
-	}
-
-	int target = openat(fd, path, O_SEARCH | flag);
-	if (target == -1)
-		return -1;
-	int ret = fstat(target, buf);
-	close(target);
-	return ret;
+	return syscall(SYS_FSTATAT, fd, path, buf, flag);
 }
 
 int lstat(const char* __restrict path, struct stat* __restrict buf)
 {
-	int fd = open(path, O_SEARCH | O_NOFOLLOW);
-	if (fd == -1)
-		return -1;
-	int ret = fstat(fd, buf);
-	close(fd);
-	return ret;
+	return syscall(SYS_STAT, path, buf, AT_SYMLINK_NOFOLLOW);
 }
 
 int stat(const char* __restrict path, struct stat* __restrict buf)
 {
-	int fd = open(path, O_SEARCH);
-	if (fd == -1)
-		return -1;
-	int ret = fstat(fd, buf);
-	close(fd);
-	return ret;
+	return syscall(SYS_STAT, path, buf, 0);
 }