selinuxfs.c

linux 内核源代码

	kfree(scon);
	return length;
}

static ssize_t sel_write_create(struct file * file, char *buf, size_t size)
{
	char *scon, *tcon;
	u32 ssid, tsid, newsid;
	u16 tclass;
	ssize_t length;
	char *newcon;
	u32 len;

	length = task_has_security(current, SECURITY__COMPUTE_CREATE);
	if (length)
		return length;

	length = -ENOMEM;
	scon = kzalloc(size+1, GFP_KERNEL);
	if (!scon)
		return length;

	tcon = kzalloc(size+1, GFP_KERNEL);
	if (!tcon)
		goto out;

	length = -EINVAL;
	if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
		goto out2;

	length = security_context_to_sid(scon, strlen(scon)+1, &ssid);
	if (length < 0)
		goto out2;
	length = security_context_to_sid(tcon, strlen(tcon)+1, &tsid);
	if (length < 0)
		goto out2;

	length = security_transition_sid(ssid, tsid, tclass, &newsid);
	if (length < 0)
		goto out2;

	length = security_sid_to_context(newsid, &newcon, &len);
	if (length < 0)
		goto out2;

	if (len > SIMPLE_TRANSACTION_LIMIT) {
		printk(KERN_ERR "%s:  context size (%u) exceeds payload "
		       "max\n", __FUNCTION__, len);
		length = -ERANGE;
		goto out3;
	}

	memcpy(buf, newcon, len);
	length = len;
out3:
	kfree(newcon);
out2:
	kfree(tcon);
out:
	kfree(scon);
	return length;
}

static ssize_t sel_write_relabel(struct file * file, char *buf, size_t size)
{
	char *scon, *tcon;
	u32 ssid, tsid, newsid;
	u16 tclass;
	ssize_t length;
	char *newcon;
	u32 len;

	length = task_has_security(current, SECURITY__COMPUTE_RELABEL);
	if (length)
		return length;

	length = -ENOMEM;
	scon = kzalloc(size+1, GFP_KERNEL);
	if (!scon)
		return length;

	tcon = kzalloc(size+1, GFP_KERNEL);
	if (!tcon)
		goto out;

	length = -EINVAL;
	if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
		goto out2;

	length = security_context_to_sid(scon, strlen(scon)+1, &ssid);
	if (length < 0)
		goto out2;
	length = security_context_to_sid(tcon, strlen(tcon)+1, &tsid);
	if (length < 0)
		goto out2;

	length = security_change_sid(ssid, tsid, tclass, &newsid);
	if (length < 0)
		goto out2;

	length = security_sid_to_context(newsid, &newcon, &len);
	if (length < 0)
		goto out2;

	if (len > SIMPLE_TRANSACTION_LIMIT) {
		length = -ERANGE;
		goto out3;
	}

	memcpy(buf, newcon, len);
	length = len;
out3:
	kfree(newcon);
out2:
	kfree(tcon);
out:
	kfree(scon);
	return length;
}

static ssize_t sel_write_user(struct file * file, char *buf, size_t size)
{
	char *con, *user, *ptr;
	u32 sid, *sids;
	ssize_t length;
	char *newcon;
	int i, rc;
	u32 len, nsids;

	length = task_has_security(current, SECURITY__COMPUTE_USER);
	if (length)
		return length;

	length = -ENOMEM;
	con = kzalloc(size+1, GFP_KERNEL);
	if (!con)
		return length;

	user = kzalloc(size+1, GFP_KERNEL);
	if (!user)
		goto out;

	length = -EINVAL;
	if (sscanf(buf, "%s %s", con, user) != 2)
		goto out2;

	length = security_context_to_sid(con, strlen(con)+1, &sid);
	if (length < 0)
		goto out2;

	length = security_get_user_sids(sid, user, &sids, &nsids);
	if (length < 0)
		goto out2;

	length = sprintf(buf, "%u", nsids) + 1;
	ptr = buf + length;
	for (i = 0; i < nsids; i++) {
		rc = security_sid_to_context(sids[i], &newcon, &len);
		if (rc) {
			length = rc;
			goto out3;
		}
		if ((length + len) >= SIMPLE_TRANSACTION_LIMIT) {
			kfree(newcon);
			length = -ERANGE;
			goto out3;
		}
		memcpy(ptr, newcon, len);
		kfree(newcon);
		ptr += len;
		length += len;
	}
out3:
	kfree(sids);
out2:
	kfree(user);
out:
	kfree(con);
	return length;
}

static ssize_t sel_write_member(struct file * file, char *buf, size_t size)
{
	char *scon, *tcon;
	u32 ssid, tsid, newsid;
	u16 tclass;
	ssize_t length;
	char *newcon;
	u32 len;

	length = task_has_security(current, SECURITY__COMPUTE_MEMBER);
	if (length)
		return length;

	length = -ENOMEM;
	scon = kzalloc(size+1, GFP_KERNEL);
	if (!scon)
		return length;

	tcon = kzalloc(size+1, GFP_KERNEL);
	if (!tcon)
		goto out;

	length = -EINVAL;
	if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
		goto out2;

	length = security_context_to_sid(scon, strlen(scon)+1, &ssid);
	if (length < 0)
		goto out2;
	length = security_context_to_sid(tcon, strlen(tcon)+1, &tsid);
	if (length < 0)
		goto out2;

	length = security_member_sid(ssid, tsid, tclass, &newsid);
	if (length < 0)
		goto out2;

	length = security_sid_to_context(newsid, &newcon, &len);
	if (length < 0)
		goto out2;

	if (len > SIMPLE_TRANSACTION_LIMIT) {
		printk(KERN_ERR "%s:  context size (%u) exceeds payload "
		       "max\n", __FUNCTION__, len);
		length = -ERANGE;
		goto out3;
	}

	memcpy(buf, newcon, len);
	length = len;
out3:
	kfree(newcon);
out2:
	kfree(tcon);
out:
	kfree(scon);
	return length;
}

static struct inode *sel_make_inode(struct super_block *sb, int mode)
{
	struct inode *ret = new_inode(sb);

	if (ret) {
		ret->i_mode = mode;
		ret->i_uid = ret->i_gid = 0;
		ret->i_blocks = 0;
		ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
	}
	return ret;
}

static ssize_t sel_read_bool(struct file *filep, char __user *buf,
			     size_t count, loff_t *ppos)
{
	char *page = NULL;
	ssize_t length;
	ssize_t ret;
	int cur_enforcing;
	struct inode *inode = filep->f_path.dentry->d_inode;
	unsigned index = inode->i_ino & SEL_INO_MASK;
	const char *name = filep->f_path.dentry->d_name.name;

	mutex_lock(&sel_mutex);

	if (index >= bool_num || strcmp(name, bool_pending_names[index])) {
		ret = -EINVAL;
		goto out;
	}

	if (count > PAGE_SIZE) {
		ret = -EINVAL;
		goto out;
	}
	if (!(page = (char*)get_zeroed_page(GFP_KERNEL))) {
		ret = -ENOMEM;
		goto out;
	}

	cur_enforcing = security_get_bool_value(index);
	if (cur_enforcing < 0) {
		ret = cur_enforcing;
		goto out;
	}
	length = scnprintf(page, PAGE_SIZE, "%d %d", cur_enforcing,
			  bool_pending_values[index]);
	ret = simple_read_from_buffer(buf, count, ppos, page, length);
out:
	mutex_unlock(&sel_mutex);
	if (page)
		free_page((unsigned long)page);
	return ret;
}

static ssize_t sel_write_bool(struct file *filep, const char __user *buf,
			      size_t count, loff_t *ppos)
{
	char *page = NULL;
	ssize_t length;
	int new_value;
	struct inode *inode = filep->f_path.dentry->d_inode;
	unsigned index = inode->i_ino & SEL_INO_MASK;
	const char *name = filep->f_path.dentry->d_name.name;

	mutex_lock(&sel_mutex);

	length = task_has_security(current, SECURITY__SETBOOL);
	if (length)
		goto out;

	if (index >= bool_num || strcmp(name, bool_pending_names[index])) {
		length = -EINVAL;
		goto out;
	}

	if (count >= PAGE_SIZE) {
		length = -ENOMEM;
		goto out;
	}

	if (*ppos != 0) {
		/* No partial writes. */
		length = -EINVAL;
		goto out;
	}
	page = (char*)get_zeroed_page(GFP_KERNEL);
	if (!page) {
		length = -ENOMEM;
		goto out;
	}

	length = -EFAULT;
	if (copy_from_user(page, buf, count))
		goto out;

	length = -EINVAL;
	if (sscanf(page, "%d", &new_value) != 1)
		goto out;

	if (new_value)
		new_value = 1;

	bool_pending_values[index] = new_value;
	length = count;

out:
	mutex_unlock(&sel_mutex);
	if (page)
		free_page((unsigned long) page);
	return length;
}

static const struct file_operations sel_bool_ops = {
	.read           = sel_read_bool,
	.write          = sel_write_bool,
};

static ssize_t sel_commit_bools_write(struct file *filep,
				      const char __user *buf,
				      size_t count, loff_t *ppos)
{
	char *page = NULL;
	ssize_t length;
	int new_value;

	mutex_lock(&sel_mutex);

	length = task_has_security(current, SECURITY__SETBOOL);
	if (length)
		goto out;

	if (count >= PAGE_SIZE) {
		length = -ENOMEM;
		goto out;
	}
	if (*ppos != 0) {
		/* No partial writes. */
		goto out;
	}
	page = (char*)get_zeroed_page(GFP_KERNEL);
	if (!page) {
		length = -ENOMEM;
		goto out;
	}

	length = -EFAULT;
	if (copy_from_user(page, buf, count))
		goto out;

	length = -EINVAL;
	if (sscanf(page, "%d", &new_value) != 1)
		goto out;

	if (new_value && bool_pending_values) {
		security_set_bools(bool_num, bool_pending_values);
	}

	length = count;

out:
	mutex_unlock(&sel_mutex);
	if (page)
		free_page((unsigned long) page);
	return length;
}

static const struct file_operations sel_commit_bools_ops = {
	.write          = sel_commit_bools_write,
};

static void sel_remove_entries(struct dentry *de)
{
	struct list_head *node;

	spin_lock(&dcache_lock);
	node = de->d_subdirs.next;
	while (node != &de->d_subdirs) {
		struct dentry *d = list_entry(node, struct dentry, d_u.d_child);
		list_del_init(node);

		if (d->d_inode) {
			d = dget_locked(d);
			spin_unlock(&dcache_lock);
			d_delete(d);
			simple_unlink(de->d_inode, d);
			dput(d);
			spin_lock(&dcache_lock);
		}
		node = de->d_subdirs.next;
	}

	spin_unlock(&dcache_lock);
}

#define BOOL_DIR_NAME "booleans"

static int sel_make_bools(void)
{
	int i, ret = 0;
	ssize_t len;
	struct dentry *dentry = NULL;
	struct dentry *dir = bool_dir;
	struct inode *inode = NULL;
	struct inode_security_struct *isec;
	char **names = NULL, *page;
	int num;
	int *values = NULL;
	u32 sid;

	/* remove any existing files */
	kfree(bool_pending_names);
	kfree(bool_pending_values);
	bool_pending_names = NULL;
	bool_pending_values = NULL;

	sel_remove_entries(dir);

	if (!(page = (char*)get_zeroed_page(GFP_KERNEL)))
		return -ENOMEM;

	ret = security_get_bools(&num, &names, &values);
	if (ret != 0)
		goto out;

	for (i = 0; i < num; i++) {
		dentry = d_alloc_name(dir, names[i]);
		if (!dentry) {
			ret = -ENOMEM;
			goto err;
		}
		inode = sel_make_inode(dir->d_sb, S_IFREG | S_IRUGO | S_IWUSR);
		if (!inode) {
			ret = -ENOMEM;
			goto err;
		}

		len = snprintf(page, PAGE_SIZE, "/%s/%s", BOOL_DIR_NAME, names[i]);
		if (len < 0) {
			ret = -EINVAL;
			goto err;
		} else if (len >= PAGE_SIZE) {
			ret = -ENAMETOOLONG;
			goto err;
		}
		isec = (struct inode_security_struct*)inode->i_security;
		if ((ret = security_genfs_sid("selinuxfs", page, SECCLASS_FILE, &sid)))
			goto err;
		isec->sid = sid;
		isec->initialized = 1;
		inode->i_fop = &sel_bool_ops;
		inode->i_ino = i|SEL_BOOL_INO_OFFSET;
		d_add(dentry, inode);
	}
	bool_num = num;
	bool_pending_names = names;
	bool_pending_values = values;
out:
	free_page((unsigned long)page);
	return ret;
err:
	if (names) {
		for (i = 0; i < num; i++)
			kfree(names[i]);
		kfree(names);
	}
	kfree(values);
	sel_remove_entries(dir);
	ret = -ENOMEM;
	goto out;
}

#define NULL_FILE_NAME "null"

struct dentry *selinux_null = NULL;

static ssize_t sel_read_avc_cache_threshold(struct file *filp, char __user *buf,
					    size_t count, loff_t *ppos)
{
	char tmpbuf[TMPBUFLEN];
	ssize_t length;

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

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

{
	char *page;
	ssize_t ret;
	int new_value;

	if (count >= PAGE_SIZE) {
		ret = -ENOMEM;
		goto out;
	}

	if (*ppos != 0) {
		/* No partial writes. */
		ret = -EINVAL;
		goto out;
	}

	page = (char*)get_zeroed_page(GFP_KERNEL);
	if (!page) {
		ret = -ENOMEM;
		goto out;
	}

	if (copy_from_user(page, buf, count)) {
		ret = -EFAULT;
		goto out_free;
	}

	if (sscanf(page, "%u", &new_value) != 1) {
		ret = -EINVAL;
		goto out;
	}

	if (new_value != avc_cache_threshold) {
		ret = task_has_security(current, SECURITY__SETSECPARAM);
		if (ret)
			goto out_free;
		avc_cache_threshold = new_value;
	}
	ret = count;
out_free:
	free_page((unsigned long)page);
out:
	return ret;
}