security/selinux/selinuxfs.c

Source file repositories/reference/linux-study-clean/security/selinux/selinuxfs.c

File Facts

System
Linux kernel
Corpus path
security/selinux/selinuxfs.c
Extension
.c
Size
48259 bytes
Lines
2017
Domain
Core OS
Bucket
Security And Isolation
Inferred role
Core OS: operation-table or driver-model contract
Status
pattern implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

static const struct file_operations sel_enforce_ops = {
	.read		= sel_read_enforce,
	.write		= sel_write_enforce,
	.llseek		= generic_file_llseek,
};

static ssize_t sel_read_handle_unknown(struct file *filp, char __user *buf,
					size_t count, loff_t *ppos)
{
	char tmpbuf[TMPBUFLEN];
	ssize_t length;
	ino_t ino = file_inode(filp)->i_ino;
	int handle_unknown = (ino == SEL_REJECT_UNKNOWN) ?
		security_get_reject_unknown() :
		!security_get_allow_unknown();

	length = scnprintf(tmpbuf, TMPBUFLEN, "%d", handle_unknown);
	return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}

static const struct file_operations sel_handle_unknown_ops = {
	.read		= sel_read_handle_unknown,
	.llseek		= generic_file_llseek,
};

static int sel_open_handle_status(struct inode *inode, struct file *filp)
{
	struct page    *status = selinux_kernel_status_page();

	if (!status)
		return -ENOMEM;

	filp->private_data = status;

	return 0;
}

static ssize_t sel_read_handle_status(struct file *filp, char __user *buf,
				      size_t count, loff_t *ppos)
{
	struct page    *status = filp->private_data;

	BUG_ON(!status);

	return simple_read_from_buffer(buf, count, ppos,
				       page_address(status),
				       sizeof(struct selinux_kernel_status));
}

static int sel_mmap_handle_status(struct file *filp,
				  struct vm_area_struct *vma)
{
	struct page    *status = filp->private_data;
	unsigned long	size = vma->vm_end - vma->vm_start;

	BUG_ON(!status);

	/* only allows one page from the head */
	if (vma->vm_pgoff > 0 || size != PAGE_SIZE)
		return -EIO;
	/* disallow writable mapping */
	if (vma->vm_flags & VM_WRITE)
		return -EPERM;
	/* disallow mprotect() turns it into writable */
	vm_flags_clear(vma, VM_MAYWRITE);

	return remap_pfn_range(vma, vma->vm_start,
			       page_to_pfn(status),
			       size, vma->vm_page_prot);
}

static const struct file_operations sel_handle_status_ops = {
	.open		= sel_open_handle_status,
	.read		= sel_read_handle_status,
	.mmap		= sel_mmap_handle_status,
	.llseek		= generic_file_llseek,
};

static ssize_t sel_write_disable(struct file *file, const char __user *buf,
				 size_t count, loff_t *ppos)

{
	/*
	 * Setting disable is no longer supported, see
	 * https://github.com/SELinuxProject/selinux-kernel/wiki/DEPRECATE-runtime-disable
	 */
	pr_err_once("SELinux: %s (%d) wrote to disable. This is no longer supported.\n",
		    current->comm, current->pid);
	return count;
}

Annotation

Implementation Notes