diff options
Diffstat (limited to 'drivers/xen/privcmd.c')
| -rw-r--r-- | drivers/xen/privcmd.c | 76 |
1 files changed, 73 insertions, 3 deletions
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index 1759cc18753f..15ba592236e8 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -12,6 +12,7 @@ #include <linux/eventfd.h> #include <linux/file.h> #include <linux/kernel.h> +#include <linux/kstrtox.h> #include <linux/module.h> #include <linux/mutex.h> #include <linux/poll.h> @@ -30,7 +31,10 @@ #include <linux/seq_file.h> #include <linux/miscdevice.h> #include <linux/moduleparam.h> +#include <linux/notifier.h> +#include <linux/security.h> #include <linux/virtio_mmio.h> +#include <linux/wait.h> #include <asm/xen/hypervisor.h> #include <asm/xen/hypercall.h> @@ -46,6 +50,7 @@ #include <xen/page.h> #include <xen/xen-ops.h> #include <xen/balloon.h> +#include <xen/xenbus.h> #ifdef CONFIG_XEN_ACPI #include <xen/acpi.h> #endif @@ -68,10 +73,20 @@ module_param_named(dm_op_buf_max_size, privcmd_dm_op_buf_max_size, uint, MODULE_PARM_DESC(dm_op_buf_max_size, "Maximum size of a dm_op hypercall buffer"); +static bool unrestricted; +module_param(unrestricted, bool, 0); +MODULE_PARM_DESC(unrestricted, + "Don't restrict hypercalls to target domain if running in a domU"); + struct privcmd_data { domid_t domid; }; +/* DOMID_INVALID implies no restriction */ +static domid_t target_domain = DOMID_INVALID; +static bool restrict_wait; +static DECLARE_WAIT_QUEUE_HEAD(restrict_wait_wq); + static int privcmd_vma_range_is_mapped( struct vm_area_struct *vma, unsigned long addr, @@ -1563,13 +1578,16 @@ static long privcmd_ioctl(struct file *file, static int privcmd_open(struct inode *ino, struct file *file) { - struct privcmd_data *data = kzalloc_obj(*data); + struct privcmd_data *data; + if (wait_event_interruptible(restrict_wait_wq, !restrict_wait) < 0) + return -EINTR; + + data = kzalloc_obj(*data); if (!data) return -ENOMEM; - /* DOMID_INVALID implies no restriction */ - data->domid = DOMID_INVALID; + data->domid = target_domain; file->private_data = data; return 0; @@ -1662,6 +1680,52 @@ static struct miscdevice privcmd_dev = { .fops = &xen_privcmd_fops, }; +static int init_restrict(struct notifier_block *notifier, + unsigned long event, + void *data) +{ + char *target; + unsigned int domid; + + /* Default to an guaranteed unused domain-id. */ + target_domain = DOMID_IDLE; + + target = xenbus_read(XBT_NIL, "target", "", NULL); + if (IS_ERR(target) || kstrtouint(target, 10, &domid)) { + pr_err("No target domain found, blocking all hypercalls\n"); + goto out; + } + + target_domain = domid; + + out: + if (!IS_ERR(target)) + kfree(target); + + restrict_wait = false; + wake_up_all(&restrict_wait_wq); + + return NOTIFY_DONE; +} + +static struct notifier_block xenstore_notifier = { + .notifier_call = init_restrict, +}; + +static void __init restrict_driver(void) +{ + if (unrestricted) { + if (security_locked_down(LOCKDOWN_XEN_USER_ACTIONS)) + pr_warn("Kernel is locked down, parameter \"unrestricted\" ignored\n"); + else + return; + } + + restrict_wait = true; + + register_xenstore_notifier(&xenstore_notifier); +} + static int __init privcmd_init(void) { int err; @@ -1669,6 +1733,9 @@ static int __init privcmd_init(void) if (!xen_domain()) return -ENODEV; + if (!xen_initial_domain()) + restrict_driver(); + err = misc_register(&privcmd_dev); if (err != 0) { pr_err("Could not register Xen privcmd device\n"); @@ -1698,6 +1765,9 @@ err_privcmdbuf: static void __exit privcmd_exit(void) { + if (!xen_initial_domain()) + unregister_xenstore_notifier(&xenstore_notifier); + privcmd_ioeventfd_exit(); privcmd_irqfd_exit(); misc_deregister(&privcmd_dev); |