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Merge branch 'next-seccomp' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Browse Source 
Pull seccomp updates from James Morris:

 - Add SECCOMP_RET_USER_NOTIF

 - seccomp fixes for sparse warnings and s390 build (Tycho)

* 'next-seccomp' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  seccomp, s390: fix build for syscall type change
  seccomp: fix poor type promotion
  samples: add an example of seccomp user trap
  seccomp: add a return code to trap to userspace
  seccomp: switch system call argument type to void *
  seccomp: hoist struct seccomp_data recalculation higher
This commit is contained in:
Linus Torvalds 2019-01-02 09:48:13 -08:00
commit d9a7fa67b4
11 changed files with 1411 additions and 24 deletions
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1
Documentation/ioctl/ioctl-number.txt
View File

@ -79,6 +79,7 @@ Code Seq#(hex) Include File Comments
0x1b all InfiniBand Subsystem <http://infiniband.sourceforge.net/>
0x20 all drivers/cdrom/cm206.h
0x22 all scsi/sg.h
'!' 00-1F uapi/linux/seccomp.h
'#' 00-3F IEEE 1394 Subsystem Block for the entire subsystem
'$' 00-0F linux/perf_counter.h, linux/perf_event.h
'%' 00-0F include/uapi/linux/stm.h

84
Documentation/userspace-api/seccomp_filter.rst
View File

@ -122,6 +122,11 @@ In precedence order, they are:
Results in the lower 16-bits of the return value being passed
to userland as the errno without executing the system call.
``SECCOMP_RET_USER_NOTIF``:
Results in a ``struct seccomp_notif`` message sent on the userspace
notification fd, if it is attached, or ``-ENOSYS`` if it is not. See below
on discussion of how to handle user notifications.
``SECCOMP_RET_TRACE``:
When returned, this value will cause the kernel to attempt to
notify a ``ptrace()``-based tracer prior to executing the system
@ -183,6 +188,85 @@ The ``samples/seccomp/`` directory contains both an x86-specific example
and a more generic example of a higher level macro interface for BPF
program generation.
Userspace Notification
======================
The ``SECCOMP_RET_USER_NOTIF`` return code lets seccomp filters pass a
particular syscall to userspace to be handled. This may be useful for
applications like container managers, which wish to intercept particular
syscalls (``mount()``, ``finit_module()``, etc.) and change their behavior.
To acquire a notification FD, use the ``SECCOMP_FILTER_FLAG_NEW_LISTENER``
argument to the ``seccomp()`` syscall:
.. code-block:: c
fd = seccomp(SECCOMP_SET_MODE_FILTER, SECCOMP_FILTER_FLAG_NEW_LISTENER, &prog);
which (on success) will return a listener fd for the filter, which can then be
passed around via ``SCM_RIGHTS`` or similar. Note that filter fds correspond to
a particular filter, and not a particular task. So if this task then forks,
notifications from both tasks will appear on the same filter fd. Reads and
writes to/from a filter fd are also synchronized, so a filter fd can safely
have many readers.
The interface for a seccomp notification fd consists of two structures:
.. code-block:: c
struct seccomp_notif_sizes {
__u16 seccomp_notif;
__u16 seccomp_notif_resp;
__u16 seccomp_data;
};
struct seccomp_notif {
__u64 id;
__u32 pid;
__u32 flags;
struct seccomp_data data;
};
struct seccomp_notif_resp {
__u64 id;
__s64 val;
__s32 error;
__u32 flags;
};
The ``struct seccomp_notif_sizes`` structure can be used to determine the size
of the various structures used in seccomp notifications. The size of ``struct
seccomp_data`` may change in the future, so code should use:
.. code-block:: c
struct seccomp_notif_sizes sizes;
seccomp(SECCOMP_GET_NOTIF_SIZES, 0, &sizes);
to determine the size of the various structures to allocate. See
samples/seccomp/user-trap.c for an example.
Users can read via ``ioctl(SECCOMP_IOCTL_NOTIF_RECV)`` (or ``poll()``) on a
seccomp notification fd to receive a ``struct seccomp_notif``, which contains
five members: the input length of the structure, a unique-per-filter ``id``,
the ``pid`` of the task which triggered this request (which may be 0 if the
task is in a pid ns not visible from the listener's pid namespace), a ``flags``
member which for now only has ``SECCOMP_NOTIF_FLAG_SIGNALED``, representing
whether or not the notification is a result of a non-fatal signal, and the
``data`` passed to seccomp. Userspace can then make a decision based on this
information about what to do, and ``ioctl(SECCOMP_IOCTL_NOTIF_SEND)`` a
response, indicating what should be returned to userspace. The ``id`` member of
``struct seccomp_notif_resp`` should be the same ``id`` as in ``struct
seccomp_notif``.
It is worth noting that ``struct seccomp_data`` contains the values of register
arguments to the syscall, but does not contain pointers to memory. The task's
memory is accessible to suitably privileged traces via ``ptrace()`` or
``/proc/pid/mem``. However, care should be taken to avoid the TOCTOU mentioned
above in this document: all arguments being read from the tracee's memory
should be read into the tracer's memory before any policy decisions are made.
This allows for an atomic decision on syscall arguments.
Sysctls
=======

2
arch/s390/kernel/compat_wrapper.c
View File

@ -164,7 +164,7 @@ COMPAT_SYSCALL_WRAP3(finit_module, int, fd, const char __user *, uargs, int, fla
COMPAT_SYSCALL_WRAP3(sched_setattr, pid_t, pid, struct sched_attr __user *, attr, unsigned int, flags);
COMPAT_SYSCALL_WRAP4(sched_getattr, pid_t, pid, struct sched_attr __user *, attr, unsigned int, size, unsigned int, flags);
COMPAT_SYSCALL_WRAP5(renameat2, int, olddfd, const char __user *, oldname, int, newdfd, const char __user *, newname, unsigned int, flags);
COMPAT_SYSCALL_WRAP3(seccomp, unsigned int, op, unsigned int, flags, const char __user *, uargs)
COMPAT_SYSCALL_WRAP3(seccomp, unsigned int, op, unsigned int, flags, void __user *, uargs)
COMPAT_SYSCALL_WRAP3(getrandom, char __user *, buf, size_t, count, unsigned int, flags)
COMPAT_SYSCALL_WRAP2(memfd_create, const char __user *, uname, unsigned int, flags)
COMPAT_SYSCALL_WRAP3(bpf, int, cmd, union bpf_attr *, attr, unsigned int, size);

9
include/linux/seccomp.h
View File

@ -4,9 +4,10 @@
#include <uapi/linux/seccomp.h>
#define SECCOMP_FILTER_FLAG_MASK (SECCOMP_FILTER_FLAG_TSYNC | \
SECCOMP_FILTER_FLAG_LOG | \
SECCOMP_FILTER_FLAG_SPEC_ALLOW)
#define SECCOMP_FILTER_FLAG_MASK (SECCOMP_FILTER_FLAG_TSYNC | \
SECCOMP_FILTER_FLAG_LOG | \
SECCOMP_FILTER_FLAG_SPEC_ALLOW | \
SECCOMP_FILTER_FLAG_NEW_LISTENER)
#ifdef CONFIG_SECCOMP
@ -43,7 +44,7 @@ extern void secure_computing_strict(int this_syscall);
#endif
extern long prctl_get_seccomp(void);
extern long prctl_set_seccomp(unsigned long, char __user *);
extern long prctl_set_seccomp(unsigned long, void __user *);
static inline int seccomp_mode(struct seccomp *s)
{

2
include/linux/syscalls.h
View File

@ -898,7 +898,7 @@ asmlinkage long sys_renameat2(int olddfd, const char __user *oldname,
int newdfd, const char __user *newname,
unsigned int flags);
asmlinkage long sys_seccomp(unsigned int op, unsigned int flags,
const char __user *uargs);
void __user *uargs);
asmlinkage long sys_getrandom(char __user *buf, size_t count,
unsigned int flags);
asmlinkage long sys_memfd_create(const char __user *uname_ptr, unsigned int flags);

40
include/uapi/linux/seccomp.h
View File

@ -15,11 +15,13 @@
#define SECCOMP_SET_MODE_STRICT 0
#define SECCOMP_SET_MODE_FILTER 1
#define SECCOMP_GET_ACTION_AVAIL 2
#define SECCOMP_GET_NOTIF_SIZES 3
/* Valid flags for SECCOMP_SET_MODE_FILTER */
#define SECCOMP_FILTER_FLAG_TSYNC (1UL << 0)
#define SECCOMP_FILTER_FLAG_LOG (1UL << 1)
#define SECCOMP_FILTER_FLAG_SPEC_ALLOW (1UL << 2)
#define SECCOMP_FILTER_FLAG_TSYNC (1UL << 0)
#define SECCOMP_FILTER_FLAG_LOG (1UL << 1)
#define SECCOMP_FILTER_FLAG_SPEC_ALLOW (1UL << 2)
#define SECCOMP_FILTER_FLAG_NEW_LISTENER (1UL << 3)
/*
* All BPF programs must return a 32-bit value.
@ -35,6 +37,7 @@
#define SECCOMP_RET_KILL SECCOMP_RET_KILL_THREAD
#define SECCOMP_RET_TRAP 0x00030000U /* disallow and force a SIGSYS */
#define SECCOMP_RET_ERRNO 0x00050000U /* returns an errno */
#define SECCOMP_RET_USER_NOTIF 0x7fc00000U /* notifies userspace */
#define SECCOMP_RET_TRACE 0x7ff00000U /* pass to a tracer or disallow */
#define SECCOMP_RET_LOG 0x7ffc0000U /* allow after logging */
#define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */
@ -60,4 +63,35 @@ struct seccomp_data {
__u64 args[6];
};
struct seccomp_notif_sizes {
__u16 seccomp_notif;
__u16 seccomp_notif_resp;
__u16 seccomp_data;
};
struct seccomp_notif {
__u64 id;
__u32 pid;
__u32 flags;
struct seccomp_data data;
};
struct seccomp_notif_resp {
__u64 id;
__s64 val;
__s32 error;
__u32 flags;
};
#define SECCOMP_IOC_MAGIC '!'
#define SECCOMP_IO(nr) _IO(SECCOMP_IOC_MAGIC, nr)
#define SECCOMP_IOR(nr, type) _IOR(SECCOMP_IOC_MAGIC, nr, type)
#define SECCOMP_IOW(nr, type) _IOW(SECCOMP_IOC_MAGIC, nr, type)
#define SECCOMP_IOWR(nr, type) _IOWR(SECCOMP_IOC_MAGIC, nr, type)
/* Flags for seccomp notification fd ioctl. */
#define SECCOMP_IOCTL_NOTIF_RECV SECCOMP_IOWR(0, struct seccomp_notif)
#define SECCOMP_IOCTL_NOTIF_SEND SECCOMP_IOWR(1, \
struct seccomp_notif_resp)
#define SECCOMP_IOCTL_NOTIF_ID_VALID SECCOMP_IOR(2, __u64)
#endif /* _UAPI_LINUX_SECCOMP_H */

467
kernel/seccomp.c
View File

@ -33,12 +33,74 @@
#endif
#ifdef CONFIG_SECCOMP_FILTER
#include <linux/file.h>
#include <linux/filter.h>
#include <linux/pid.h>
#include <linux/ptrace.h>
#include <linux/security.h>
#include <linux/tracehook.h>
#include <linux/uaccess.h>
#include <linux/anon_inodes.h>
enum notify_state {
SECCOMP_NOTIFY_INIT,
SECCOMP_NOTIFY_SENT,
SECCOMP_NOTIFY_REPLIED,
};
struct seccomp_knotif {
/* The struct pid of the task whose filter triggered the notification */
struct task_struct *task;
/* The "cookie" for this request; this is unique for this filter. */
u64 id;
/*
* The seccomp data. This pointer is valid the entire time this
* notification is active, since it comes from __seccomp_filter which
* eclipses the entire lifecycle here.
*/
const struct seccomp_data *data;
/*
* Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
* struct seccomp_knotif is created and starts out in INIT. Once the
* handler reads the notification off of an FD, it transitions to SENT.
* If a signal is received the state transitions back to INIT and
* another message is sent. When the userspace handler replies, state
* transitions to REPLIED.
*/
enum notify_state state;
/* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
int error;
long val;
/* Signals when this has entered SECCOMP_NOTIFY_REPLIED */
struct completion ready;
struct list_head list;
};
/**
* struct notification - container for seccomp userspace notifications. Since
* most seccomp filters will not have notification listeners attached and this
* structure is fairly large, we store the notification-specific stuff in a
* separate structure.
*
* @request: A semaphore that users of this notification can wait on for
* changes. Actual reads and writes are still controlled with
* filter->notify_lock.
* @next_id: The id of the next request.
* @notifications: A list of struct seccomp_knotif elements.
* @wqh: A wait queue for poll.
*/
struct notification {
struct semaphore request;
u64 next_id;
struct list_head notifications;
wait_queue_head_t wqh;
};
/**
* struct seccomp_filter - container for seccomp BPF programs
@ -50,6 +112,8 @@
* @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
* @prev: points to a previously installed, or inherited, filter
* @prog: the BPF program to evaluate
* @notif: the struct that holds all notification related information
* @notify_lock: A lock for all notification-related accesses.
*
* seccomp_filter objects are organized in a tree linked via the @prev
* pointer. For any task, it appears to be a singly-linked list starting
@ -66,6 +130,8 @@ struct seccomp_filter {
bool log;
struct seccomp_filter *prev;
struct bpf_prog *prog;
struct notification *notif;
struct mutex notify_lock;
};
/* Limit any path through the tree to 256KB worth of instructions. */
@ -188,7 +254,6 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
static u32 seccomp_run_filters(const struct seccomp_data *sd,
struct seccomp_filter **match)
{
struct seccomp_data sd_local;
u32 ret = SECCOMP_RET_ALLOW;
/* Make sure cross-thread synced filter points somewhere sane. */
struct seccomp_filter *f =
@ -198,11 +263,6 @@ static u32 seccomp_run_filters(const struct seccomp_data *sd,
if (WARN_ON(f == NULL))
return SECCOMP_RET_KILL_PROCESS;
if (!sd) {
populate_seccomp_data(&sd_local);
sd = &sd_local;
}
/*
* All filters in the list are evaluated and the lowest BPF return
* value always takes priority (ignoring the DATA).
@ -392,6 +452,7 @@ static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
if (!sfilter)
return ERR_PTR(-ENOMEM);
mutex_init(&sfilter->notify_lock);
ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
seccomp_check_filter, save_orig);
if (ret < 0) {
@ -485,7 +546,6 @@ static long seccomp_attach_filter(unsigned int flags,
static void __get_seccomp_filter(struct seccomp_filter *filter)
{
/* Reference count is bounded by the number of total processes. */
refcount_inc(&filter->usage);
}
@ -556,11 +616,13 @@ static void seccomp_send_sigsys(int syscall, int reason)
#define SECCOMP_LOG_TRACE (1 << 4)
#define SECCOMP_LOG_LOG (1 << 5)
#define SECCOMP_LOG_ALLOW (1 << 6)
#define SECCOMP_LOG_USER_NOTIF (1 << 7)
static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
SECCOMP_LOG_KILL_THREAD |
SECCOMP_LOG_TRAP |
SECCOMP_LOG_ERRNO |
SECCOMP_LOG_USER_NOTIF |
SECCOMP_LOG_TRACE |
SECCOMP_LOG_LOG;
@ -581,6 +643,9 @@ static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
case SECCOMP_RET_TRACE:
log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
break;
case SECCOMP_RET_USER_NOTIF:
log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
break;
case SECCOMP_RET_LOG:
log = seccomp_actions_logged & SECCOMP_LOG_LOG;
break;
@ -652,12 +717,75 @@ void secure_computing_strict(int this_syscall)
#else
#ifdef CONFIG_SECCOMP_FILTER
static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
{
/*
* Note: overflow is ok here, the id just needs to be unique per
* filter.
*/
lockdep_assert_held(&filter->notify_lock);
return filter->notif->next_id++;
}
static void seccomp_do_user_notification(int this_syscall,
struct seccomp_filter *match,
const struct seccomp_data *sd)
{
int err;
long ret = 0;
struct seccomp_knotif n = {};
mutex_lock(&match->notify_lock);
err = -ENOSYS;
if (!match->notif)
goto out;
n.task = current;
n.state = SECCOMP_NOTIFY_INIT;
n.data = sd;
n.id = seccomp_next_notify_id(match);
init_completion(&n.ready);
list_add(&n.list, &match->notif->notifications);
up(&match->notif->request);
wake_up_poll(&match->notif->wqh, EPOLLIN | EPOLLRDNORM);
mutex_unlock(&match->notify_lock);
/*
* This is where we wait for a reply from userspace.
*/
err = wait_for_completion_interruptible(&n.ready);
mutex_lock(&match->notify_lock);
if (err == 0) {
ret = n.val;
err = n.error;
}
/*
* Note that it's possible the listener died in between the time when
* we were notified of a respons (or a signal) and when we were able to
* re-acquire the lock, so only delete from the list if the
* notification actually exists.
*
* Also note that this test is only valid because there's no way to
* *reattach* to a notifier right now. If one is added, we'll need to
* keep track of the notif itself and make sure they match here.
*/
if (match->notif)
list_del(&n.list);
out:
mutex_unlock(&match->notify_lock);
syscall_set_return_value(current, task_pt_regs(current),
err, ret);
}
static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
const bool recheck_after_trace)
{
u32 filter_ret, action;
struct seccomp_filter *match = NULL;
int data;
struct seccomp_data sd_local;
/*
* Make sure that any changes to mode from another thread have
@ -665,6 +793,11 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
*/
rmb();
if (!sd) {
populate_seccomp_data(&sd_local);
sd = &sd_local;
}
filter_ret = seccomp_run_filters(sd, &match);
data = filter_ret & SECCOMP_RET_DATA;
action = filter_ret & SECCOMP_RET_ACTION_FULL;
@ -728,6 +861,10 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
return 0;
case SECCOMP_RET_USER_NOTIF:
seccomp_do_user_notification(this_syscall, match, sd);
goto skip;
case SECCOMP_RET_LOG:
seccomp_log(this_syscall, 0, action, true);
return 0;
@ -834,6 +971,262 @@ out:
}
#ifdef CONFIG_SECCOMP_FILTER
static int seccomp_notify_release(struct inode *inode, struct file *file)
{
struct seccomp_filter *filter = file->private_data;
struct seccomp_knotif *knotif;
mutex_lock(&filter->notify_lock);
/*
* If this file is being closed because e.g. the task who owned it
* died, let's wake everyone up who was waiting on us.
*/
list_for_each_entry(knotif, &filter->notif->notifications, list) {
if (knotif->state == SECCOMP_NOTIFY_REPLIED)
continue;
knotif->state = SECCOMP_NOTIFY_REPLIED;
knotif->error = -ENOSYS;
knotif->val = 0;
complete(&knotif->ready);
}
kfree(filter->notif);
filter->notif = NULL;
mutex_unlock(&filter->notify_lock);
__put_seccomp_filter(filter);
return 0;
}
static long seccomp_notify_recv(struct seccomp_filter *filter,
void __user *buf)
{
struct seccomp_knotif *knotif = NULL, *cur;
struct seccomp_notif unotif;
ssize_t ret;
memset(&unotif, 0, sizeof(unotif));
ret = down_interruptible(&filter->notif->request);
if (ret < 0)
return ret;
mutex_lock(&filter->notify_lock);
list_for_each_entry(cur, &filter->notif->notifications, list) {
if (cur->state == SECCOMP_NOTIFY_INIT) {
knotif = cur;
break;
}
}
/*
* If we didn't find a notification, it could be that the task was
* interrupted by a fatal signal between the time we were woken and
* when we were able to acquire the rw lock.
*/
if (!knotif) {
ret = -ENOENT;
goto out;
}
unotif.id = knotif->id;
unotif.pid = task_pid_vnr(knotif->task);
unotif.data = *(knotif->data);
knotif->state = SECCOMP_NOTIFY_SENT;
wake_up_poll(&filter->notif->wqh, EPOLLOUT | EPOLLWRNORM);
ret = 0;
out:
mutex_unlock(&filter->notify_lock);
if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
ret = -EFAULT;
/*
* Userspace screwed up. To make sure that we keep this
* notification alive, let's reset it back to INIT. It
* may have died when we released the lock, so we need to make
* sure it's still around.
*/
knotif = NULL;
mutex_lock(&filter->notify_lock);
list_for_each_entry(cur, &filter->notif->notifications, list) {
if (cur->id == unotif.id) {
knotif = cur;
break;
}
}
if (knotif) {
knotif->state = SECCOMP_NOTIFY_INIT;
up(&filter->notif->request);
}
mutex_unlock(&filter->notify_lock);
}
return ret;
}
static long seccomp_notify_send(struct seccomp_filter *filter,
void __user *buf)
{
struct seccomp_notif_resp resp = {};
struct seccomp_knotif *knotif = NULL, *cur;
long ret;
if (copy_from_user(&resp, buf, sizeof(resp)))
return -EFAULT;
if (resp.flags)
return -EINVAL;
ret = mutex_lock_interruptible(&filter->notify_lock);
if (ret < 0)
return ret;
list_for_each_entry(cur, &filter->notif->notifications, list) {
if (cur->id == resp.id) {
knotif = cur;
break;
}
}
if (!knotif) {
ret = -ENOENT;
goto out;
}
/* Allow exactly one reply. */
if (knotif->state != SECCOMP_NOTIFY_SENT) {
ret = -EINPROGRESS;
goto out;
}
ret = 0;
knotif->state = SECCOMP_NOTIFY_REPLIED;
knotif->error = resp.error;
knotif->val = resp.val;
complete(&knotif->ready);
out:
mutex_unlock(&filter->notify_lock);
return ret;
}
static long seccomp_notify_id_valid(struct seccomp_filter *filter,
void __user *buf)
{
struct seccomp_knotif *knotif = NULL;
u64 id;
long ret;
if (copy_from_user(&id, buf, sizeof(id)))
return -EFAULT;
ret = mutex_lock_interruptible(&filter->notify_lock);
if (ret < 0)
return ret;
ret = -ENOENT;
list_for_each_entry(knotif, &filter->notif->notifications, list) {
if (knotif->id == id) {
if (knotif->state == SECCOMP_NOTIFY_SENT)
ret = 0;
goto out;
}
}
out:
mutex_unlock(&filter->notify_lock);
return ret;
}
static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct seccomp_filter *filter = file->private_data;
void __user *buf = (void __user *)arg;
switch (cmd) {
case SECCOMP_IOCTL_NOTIF_RECV:
return seccomp_notify_recv(filter, buf);
case SECCOMP_IOCTL_NOTIF_SEND:
return seccomp_notify_send(filter, buf);
case SECCOMP_IOCTL_NOTIF_ID_VALID:
return seccomp_notify_id_valid(filter, buf);
default:
return -EINVAL;
}
}
static __poll_t seccomp_notify_poll(struct file *file,
struct poll_table_struct *poll_tab)
{
struct seccomp_filter *filter = file->private_data;
__poll_t ret = 0;
struct seccomp_knotif *cur;
poll_wait(file, &filter->notif->wqh, poll_tab);
if (mutex_lock_interruptible(&filter->notify_lock) < 0)
return EPOLLERR;
list_for_each_entry(cur, &filter->notif->notifications, list) {
if (cur->state == SECCOMP_NOTIFY_INIT)
ret |= EPOLLIN | EPOLLRDNORM;
if (cur->state == SECCOMP_NOTIFY_SENT)
ret |= EPOLLOUT | EPOLLWRNORM;
if ((ret & EPOLLIN) && (ret & EPOLLOUT))
break;
}
mutex_unlock(&filter->notify_lock);
return ret;
}
static const struct file_operations seccomp_notify_ops = {
.poll = seccomp_notify_poll,
.release = seccomp_notify_release,
.unlocked_ioctl = seccomp_notify_ioctl,
};
static struct file *init_listener(struct seccomp_filter *filter)
{
struct file *ret = ERR_PTR(-EBUSY);
struct seccomp_filter *cur;
for (cur = current->seccomp.filter; cur; cur = cur->prev) {
if (cur->notif)
goto out;
}
ret = ERR_PTR(-ENOMEM);
filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
if (!filter->notif)
goto out;
sema_init(&filter->notif->request, 0);
filter->notif->next_id = get_random_u64();
INIT_LIST_HEAD(&filter->notif->notifications);
init_waitqueue_head(&filter->notif->wqh);
ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
filter, O_RDWR);
if (IS_ERR(ret))
goto out_notif;
/* The file has a reference to it now */
__get_seccomp_filter(filter);
out_notif:
if (IS_ERR(ret))
kfree(filter->notif);
out:
return ret;
}
/**
* seccomp_set_mode_filter: internal function for setting seccomp filter
* @flags: flags to change filter behavior
@ -853,6 +1246,8 @@ static long seccomp_set_mode_filter(unsigned int flags,
const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
struct seccomp_filter *prepared = NULL;
long ret = -EINVAL;
int listener = -1;
struct file *listener_f = NULL;
/* Validate flags. */
if (flags & ~SECCOMP_FILTER_FLAG_MASK)
@ -863,13 +1258,28 @@ static long seccomp_set_mode_filter(unsigned int flags,
if (IS_ERR(prepared))
return PTR_ERR(prepared);
if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
listener = get_unused_fd_flags(O_CLOEXEC);
if (listener < 0) {
ret = listener;
goto out_free;
}
listener_f = init_listener(prepared);
if (IS_ERR(listener_f)) {
put_unused_fd(listener);
ret = PTR_ERR(listener_f);
goto out_free;
}
}
/*
* Make sure we cannot change seccomp or nnp state via TSYNC
* while another thread is in the middle of calling exec.
*/
if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
mutex_lock_killable(&current->signal->cred_guard_mutex))
goto out_free;
goto out_put_fd;
spin_lock_irq(&current->sighand->siglock);
@ -887,6 +1297,16 @@ out:
spin_unlock_irq(&current->sighand->siglock);
if (flags & SECCOMP_FILTER_FLAG_TSYNC)
mutex_unlock(&current->signal->cred_guard_mutex);
out_put_fd:
if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
if (ret < 0) {
fput(listener_f);
put_unused_fd(listener);
} else {
fd_install(listener, listener_f);
ret = listener;
}
}
out_free:
seccomp_filter_free(prepared);
return ret;
@ -911,6 +1331,7 @@ static long seccomp_get_action_avail(const char __user *uaction)
case SECCOMP_RET_KILL_THREAD:
case SECCOMP_RET_TRAP:
case SECCOMP_RET_ERRNO:
case SECCOMP_RET_USER_NOTIF:
case SECCOMP_RET_TRACE:
case SECCOMP_RET_LOG:
case SECCOMP_RET_ALLOW:
@ -922,9 +1343,23 @@ static long seccomp_get_action_avail(const char __user *uaction)
return 0;
}
static long seccomp_get_notif_sizes(void __user *usizes)
{
struct seccomp_notif_sizes sizes = {
.seccomp_notif = sizeof(struct seccomp_notif),
.seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
.seccomp_data = sizeof(struct seccomp_data),
};
if (copy_to_user(usizes, &sizes, sizeof(sizes)))
return -EFAULT;
return 0;
}
/* Common entry point for both prctl and syscall. */
static long do_seccomp(unsigned int op, unsigned int flags,
const char __user *uargs)
void __user *uargs)
{
switch (op) {
case SECCOMP_SET_MODE_STRICT:
@ -938,13 +1373,18 @@ static long do_seccomp(unsigned int op, unsigned int flags,
return -EINVAL;
return seccomp_get_action_avail(uargs);
case SECCOMP_GET_NOTIF_SIZES:
if (flags != 0)
return -EINVAL;
return seccomp_get_notif_sizes(uargs);
default:
return -EINVAL;
}
}
SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
const char __user *, uargs)
void __user *, uargs)
{
return do_seccomp(op, flags, uargs);
}
@ -956,10 +1396,10 @@ SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
*
* Returns 0 on success or -EINVAL on failure.
*/
long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
{
unsigned int op;
char __user *uargs;
void __user *uargs;
switch (seccomp_mode) {
case SECCOMP_MODE_STRICT:
@ -1111,6 +1551,7 @@ long seccomp_get_metadata(struct task_struct *task,
#define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
#define SECCOMP_RET_TRAP_NAME "trap"
#define SECCOMP_RET_ERRNO_NAME "errno"
#define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
#define SECCOMP_RET_TRACE_NAME "trace"
#define SECCOMP_RET_LOG_NAME "log"
#define SECCOMP_RET_ALLOW_NAME "allow"
@ -1120,6 +1561,7 @@ static const char seccomp_actions_avail[] =
SECCOMP_RET_KILL_THREAD_NAME " "
SECCOMP_RET_TRAP_NAME " "
SECCOMP_RET_ERRNO_NAME " "
SECCOMP_RET_USER_NOTIF_NAME " "
SECCOMP_RET_TRACE_NAME " "
SECCOMP_RET_LOG_NAME " "
SECCOMP_RET_ALLOW_NAME;
@ -1134,6 +1576,7 @@ static const struct seccomp_log_name seccomp_log_names[] = {
{ SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
{ SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
{ SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
{ SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
{ SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
{ SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
{ SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },

1
samples/seccomp/.gitignore vendored
View File

@ -1,3 +1,4 @@
bpf-direct
bpf-fancy
dropper
user-trap

7
samples/seccomp/Makefile
View File

@ -1,6 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
ifndef CROSS_COMPILE
hostprogs-$(CONFIG_SAMPLE_SECCOMP) := bpf-fancy dropper bpf-direct
hostprogs-$(CONFIG_SAMPLE_SECCOMP) := bpf-fancy dropper bpf-direct user-trap
HOSTCFLAGS_bpf-fancy.o += -I$(objtree)/usr/include
HOSTCFLAGS_bpf-fancy.o += -idirafter $(objtree)/include
@ -16,6 +16,10 @@ HOSTCFLAGS_bpf-direct.o += -I$(objtree)/usr/include
HOSTCFLAGS_bpf-direct.o += -idirafter $(objtree)/include
bpf-direct-objs := bpf-direct.o
HOSTCFLAGS_user-trap.o += -I$(objtree)/usr/include
HOSTCFLAGS_user-trap.o += -idirafter $(objtree)/include
user-trap-objs := user-trap.o
# Try to match the kernel target.
ifndef CONFIG_64BIT
@ -33,6 +37,7 @@ HOSTCFLAGS_bpf-fancy.o += $(MFLAG)
HOSTLDLIBS_bpf-direct += $(MFLAG)
HOSTLDLIBS_bpf-fancy += $(MFLAG)
HOSTLDLIBS_dropper += $(MFLAG)
HOSTLDLIBS_user-trap += $(MFLAG)
endif
always := $(hostprogs-m)
endif

375
samples/seccomp/user-trap.c Normal file
View File

@ -0,0 +1,375 @@
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <stddef.h>
#include <sys/sysmacros.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <sys/user.h>
#include <sys/ioctl.h>
#include <sys/ptrace.h>
#include <sys/mount.h>
#include <linux/limits.h>
#include <linux/filter.h>
#include <linux/seccomp.h>
#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
static int seccomp(unsigned int op, unsigned int flags, void *args)
{
errno = 0;
return syscall(__NR_seccomp, op, flags, args);
}
static int send_fd(int sock, int fd)
{
struct msghdr msg = {};
struct cmsghdr *cmsg;
char buf[CMSG_SPACE(sizeof(int))] = {0}, c = 'c';
struct iovec io = {
.iov_base = &c,
.iov_len = 1,
};
msg.msg_iov = &io;
msg.msg_iovlen = 1;
msg.msg_control = buf;
msg.msg_controllen = sizeof(buf);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
*((int *)CMSG_DATA(cmsg)) = fd;
msg.msg_controllen = cmsg->cmsg_len;
if (sendmsg(sock, &msg, 0) < 0) {
perror("sendmsg");
return -1;
}
return 0;
}
static int recv_fd(int sock)
{
struct msghdr msg = {};
struct cmsghdr *cmsg;
char buf[CMSG_SPACE(sizeof(int))] = {0}, c = 'c';
struct iovec io = {
.iov_base = &c,
.iov_len = 1,
};
msg.msg_iov = &io;
msg.msg_iovlen = 1;
msg.msg_control = buf;
msg.msg_controllen = sizeof(buf);
if (recvmsg(sock, &msg, 0) < 0) {
perror("recvmsg");
return -1;
}
cmsg = CMSG_FIRSTHDR(&msg);
return *((int *)CMSG_DATA(cmsg));
}
static int user_trap_syscall(int nr, unsigned int flags)
{
struct sock_filter filter[] = {
BPF_STMT(BPF_LD+BPF_W+BPF_ABS,
offsetof(struct seccomp_data, nr)),
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, nr, 0, 1),
BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_USER_NOTIF),
BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW),
};
struct sock_fprog prog = {
.len = (unsigned short)ARRAY_SIZE(filter),
.filter = filter,
};
return seccomp(SECCOMP_SET_MODE_FILTER, flags, &prog);
}
static int handle_req(struct seccomp_notif *req,
struct seccomp_notif_resp *resp, int listener)
{
char path[PATH_MAX], source[PATH_MAX], target[PATH_MAX];
int ret = -1, mem;
resp->id = req->id;
resp->error = -EPERM;
resp->val = 0;
if (req->data.nr != __NR_mount) {
fprintf(stderr, "huh? trapped something besides mount? %d\n", req->data.nr);
return -1;
}
/* Only allow bind mounts. */
if (!(req->data.args[3] & MS_BIND))
return 0;
/*
* Ok, let's read the task's memory to see where they wanted their
* mount to go.
*/
snprintf(path, sizeof(path), "/proc/%d/mem", req->pid);
mem = open(path, O_RDONLY);
if (mem < 0) {
perror("open mem");
return -1;
}
/*
* Now we avoid a TOCTOU: we referred to a pid by its pid, but since
* the pid that made the syscall may have died, we need to confirm that
* the pid is still valid after we open its /proc/pid/mem file. We can
* ask the listener fd this as follows.
*
* Note that this check should occur *after* any task-specific
* resources are opened, to make sure that the task has not died and
* we're not wrongly reading someone else's state in order to make
* decisions.
*/
if (ioctl(listener, SECCOMP_IOCTL_NOTIF_ID_VALID, &req->id) < 0) {
fprintf(stderr, "task died before we could map its memory\n");
goto out;
}
/*
* Phew, we've got the right /proc/pid/mem. Now we can read it. Note
* that to avoid another TOCTOU, we should read all of the pointer args
* before we decide to allow the syscall.
*/
if (lseek(mem, req->data.args[0], SEEK_SET) < 0) {
perror("seek");
goto out;
}
ret = read(mem, source, sizeof(source));
if (ret < 0) {
perror("read");
goto out;
}
if (lseek(mem, req->data.args[1], SEEK_SET) < 0) {
perror("seek");
goto out;
}
ret = read(mem, target, sizeof(target));
if (ret < 0) {
perror("read");
goto out;
}
/*
* Our policy is to only allow bind mounts inside /tmp. This isn't very
* interesting, because we could do unprivlieged bind mounts with user
* namespaces already, but you get the idea.
*/
if (!strncmp(source, "/tmp/", 5) && !strncmp(target, "/tmp/", 5)) {
if (mount(source, target, NULL, req->data.args[3], NULL) < 0) {
ret = -1;
perror("actual mount");
goto out;
}
resp->error = 0;
}
/* Even if we didn't allow it because of policy, generating the
* response was be a success, because we want to tell the worker EPERM.
*/
ret = 0;
out:
close(mem);
return ret;
}
int main(void)
{
int sk_pair[2], ret = 1, status, listener;
pid_t worker = 0 , tracer = 0;
if (socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, sk_pair) < 0) {
perror("socketpair");
return 1;
}
worker = fork();
if (worker < 0) {
perror("fork");
goto close_pair;
}
if (worker == 0) {
listener = user_trap_syscall(__NR_mount,
SECCOMP_FILTER_FLAG_NEW_LISTENER);
if (listener < 0) {
perror("seccomp");
exit(1);
}
/*
* Drop privileges. We definitely can't mount as uid 1000.
*/
if (setuid(1000) < 0) {
perror("setuid");
exit(1);
}
/*
* Send the listener to the parent; also serves as
* synchronization.
*/
if (send_fd(sk_pair[1], listener) < 0)
exit(1);
close(listener);
if (mkdir("/tmp/foo", 0755) < 0) {
perror("mkdir");
exit(1);
}
/*
* Try a bad mount just for grins.
*/
if (mount("/dev/sda", "/tmp/foo", NULL, 0, NULL) != -1) {
fprintf(stderr, "huh? mounted /dev/sda?\n");
exit(1);
}
if (errno != EPERM) {
perror("bad error from mount");
exit(1);
}
/*
* Ok, we expect this one to succeed.
*/
if (mount("/tmp/foo", "/tmp/foo", NULL, MS_BIND, NULL) < 0) {
perror("mount");
exit(1);
}
exit(0);
}
/*
* Get the listener from the child.
*/
listener = recv_fd(sk_pair[0]);
if (listener < 0)
goto out_kill;
/*
* Fork a task to handle the requests. This isn't strictly necessary,
* but it makes the particular writing of this sample easier, since we
* can just wait ofr the tracee to exit and kill the tracer.
*/
tracer = fork();
if (tracer < 0) {
perror("fork");
goto out_kill;
}
if (tracer == 0) {
struct seccomp_notif *req;
struct seccomp_notif_resp *resp;
struct seccomp_notif_sizes sizes;
if (seccomp(SECCOMP_GET_NOTIF_SIZES, 0, &sizes) < 0) {
perror("seccomp(GET_NOTIF_SIZES)");
goto out_close;
}
req = malloc(sizes.seccomp_notif);
if (!req)
goto out_close;
memset(req, 0, sizeof(*req));
resp = malloc(sizes.seccomp_notif_resp);
if (!resp)
goto out_req;
memset(resp, 0, sizeof(*resp));
while (1) {
if (ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, req)) {
perror("ioctl recv");
goto out_resp;
}
if (handle_req(req, resp, listener) < 0)
goto out_resp;
/*
* ENOENT here means that the task may have gotten a
* signal and restarted the syscall. It's up to the
* handler to decide what to do in this case, but for
* the sample code, we just ignore it. Probably
* something better should happen, like undoing the
* mount, or keeping track of the args to make sure we
* don't do it again.
*/
if (ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, resp) < 0 &&
errno != ENOENT) {
perror("ioctl send");
goto out_resp;
}
}
out_resp:
free(resp);
out_req:
free(req);
out_close:
close(listener);
exit(1);
}
close(listener);
if (waitpid(worker, &status, 0) != worker) {
perror("waitpid");
goto out_kill;
}
if (umount2("/tmp/foo", MNT_DETACH) < 0 && errno != EINVAL) {
perror("umount2");
goto out_kill;
}
if (remove("/tmp/foo") < 0 && errno != ENOENT) {
perror("remove");
exit(1);
}
if (!WIFEXITED(status) || WEXITSTATUS(status)) {
fprintf(stderr, "worker exited nonzero\n");
goto out_kill;
}
ret = 0;
out_kill:
if (tracer > 0)
kill(tracer, SIGKILL);
if (worker > 0)
kill(worker, SIGKILL);
close_pair:
close(sk_pair[0]);
close(sk_pair[1]);
return ret;
}

447
tools/testing/selftests/seccomp/seccomp_bpf.c
View File

@ -5,6 +5,7 @@
* Test code for seccomp bpf.
*/
#define _GNU_SOURCE
#include <sys/types.h>
/*
@ -40,10 +41,12 @@
#include <sys/fcntl.h>
#include <sys/mman.h>
#include <sys/times.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#define _GNU_SOURCE
#include <unistd.h>
#include <sys/syscall.h>
#include <poll.h>
#include "../kselftest_harness.h"
@ -133,6 +136,10 @@ struct seccomp_data {
#define SECCOMP_GET_ACTION_AVAIL 2
#endif
#ifndef SECCOMP_GET_NOTIF_SIZES
#define SECCOMP_GET_NOTIF_SIZES 3
#endif
#ifndef SECCOMP_FILTER_FLAG_TSYNC
#define SECCOMP_FILTER_FLAG_TSYNC (1UL << 0)
#endif
@ -154,6 +161,44 @@ struct seccomp_metadata {
};
#endif
#ifndef SECCOMP_FILTER_FLAG_NEW_LISTENER
#define SECCOMP_FILTER_FLAG_NEW_LISTENER (1UL << 3)
#define SECCOMP_RET_USER_NOTIF 0x7fc00000U
#define SECCOMP_IOC_MAGIC '!'
#define SECCOMP_IO(nr) _IO(SECCOMP_IOC_MAGIC, nr)
#define SECCOMP_IOR(nr, type) _IOR(SECCOMP_IOC_MAGIC, nr, type)
#define SECCOMP_IOW(nr, type) _IOW(SECCOMP_IOC_MAGIC, nr, type)
#define SECCOMP_IOWR(nr, type) _IOWR(SECCOMP_IOC_MAGIC, nr, type)
/* Flags for seccomp notification fd ioctl. */
#define SECCOMP_IOCTL_NOTIF_RECV SECCOMP_IOWR(0, struct seccomp_notif)
#define SECCOMP_IOCTL_NOTIF_SEND SECCOMP_IOWR(1, \
struct seccomp_notif_resp)
#define SECCOMP_IOCTL_NOTIF_ID_VALID SECCOMP_IOR(2, __u64)
struct seccomp_notif {
__u64 id;
__u32 pid;
__u32 flags;
struct seccomp_data data;
};
struct seccomp_notif_resp {
__u64 id;
__s64 val;
__s32 error;
__u32 flags;
};
struct seccomp_notif_sizes {
__u16 seccomp_notif;
__u16 seccomp_notif_resp;
__u16 seccomp_data;
};
#endif
#ifndef seccomp
int seccomp(unsigned int op, unsigned int flags, void *args)
{
@ -2077,7 +2122,8 @@ TEST(detect_seccomp_filter_flags)
{
unsigned int flags[] = { SECCOMP_FILTER_FLAG_TSYNC,
SECCOMP_FILTER_FLAG_LOG,
SECCOMP_FILTER_FLAG_SPEC_ALLOW };
SECCOMP_FILTER_FLAG_SPEC_ALLOW,
SECCOMP_FILTER_FLAG_NEW_LISTENER };
unsigned int flag, all_flags;
int i;
long ret;
@ -2938,6 +2984,403 @@ skip:
ASSERT_EQ(0, kill(pid, SIGKILL));
}
static int user_trap_syscall(int nr, unsigned int flags)
{
struct sock_filter filter[] = {
BPF_STMT(BPF_LD+BPF_W+BPF_ABS,
offsetof(struct seccomp_data, nr)),
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, nr, 0, 1),
BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_USER_NOTIF),
BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW),
};
struct sock_fprog prog = {
.len = (unsigned short)ARRAY_SIZE(filter),
.filter = filter,
};
return seccomp(SECCOMP_SET_MODE_FILTER, flags, &prog);
}
#define USER_NOTIF_MAGIC 116983961184613L
TEST(user_notification_basic)
{
pid_t pid;
long ret;
int status, listener;
struct seccomp_notif req = {};
struct seccomp_notif_resp resp = {};
struct pollfd pollfd;
struct sock_filter filter[] = {
BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
};
struct sock_fprog prog = {
.len = (unsigned short)ARRAY_SIZE(filter),
.filter = filter,
};
pid = fork();
ASSERT_GE(pid, 0);
/* Check that we get -ENOSYS with no listener attached */
if (pid == 0) {
if (user_trap_syscall(__NR_getpid, 0) < 0)
exit(1);
ret = syscall(__NR_getpid);
exit(ret >= 0 || errno != ENOSYS);
}
EXPECT_EQ(waitpid(pid, &status, 0), pid);
EXPECT_EQ(true, WIFEXITED(status));
EXPECT_EQ(0, WEXITSTATUS(status));
/* Add some no-op filters so for grins. */
EXPECT_EQ(seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog), 0);
EXPECT_EQ(seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog), 0);
EXPECT_EQ(seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog), 0);
EXPECT_EQ(seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog), 0);
/* Check that the basic notification machinery works */
listener = user_trap_syscall(__NR_getpid,
SECCOMP_FILTER_FLAG_NEW_LISTENER);
EXPECT_GE(listener, 0);
/* Installing a second listener in the chain should EBUSY */
EXPECT_EQ(user_trap_syscall(__NR_getpid,
SECCOMP_FILTER_FLAG_NEW_LISTENER),
-1);
EXPECT_EQ(errno, EBUSY);
pid = fork();
ASSERT_GE(pid, 0);
if (pid == 0) {
ret = syscall(__NR_getpid);
exit(ret != USER_NOTIF_MAGIC);
}
pollfd.fd = listener;
pollfd.events = POLLIN | POLLOUT;
EXPECT_GT(poll(&pollfd, 1, -1), 0);
EXPECT_EQ(pollfd.revents, POLLIN);
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
pollfd.fd = listener;
pollfd.events = POLLIN | POLLOUT;
EXPECT_GT(poll(&pollfd, 1, -1), 0);
EXPECT_EQ(pollfd.revents, POLLOUT);
EXPECT_EQ(req.data.nr, __NR_getpid);
resp.id = req.id;
resp.error = 0;
resp.val = USER_NOTIF_MAGIC;
/* check that we make sure flags == 0 */
resp.flags = 1;
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, &resp), -1);
EXPECT_EQ(errno, EINVAL);
resp.flags = 0;
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, &resp), 0);
EXPECT_EQ(waitpid(pid, &status, 0), pid);
EXPECT_EQ(true, WIFEXITED(status));
EXPECT_EQ(0, WEXITSTATUS(status));
}
TEST(user_notification_kill_in_middle)
{
pid_t pid;
long ret;
int listener;
struct seccomp_notif req = {};
struct seccomp_notif_resp resp = {};
listener = user_trap_syscall(__NR_getpid,
SECCOMP_FILTER_FLAG_NEW_LISTENER);
EXPECT_GE(listener, 0);
/*
* Check that nothing bad happens when we kill the task in the middle
* of a syscall.
*/
pid = fork();
ASSERT_GE(pid, 0);
if (pid == 0) {
ret = syscall(__NR_getpid);
exit(ret != USER_NOTIF_MAGIC);
}
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_ID_VALID, &req.id), 0);
EXPECT_EQ(kill(pid, SIGKILL), 0);
EXPECT_EQ(waitpid(pid, NULL, 0), pid);
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_ID_VALID, &req.id), -1);
resp.id = req.id;
ret = ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, &resp);
EXPECT_EQ(ret, -1);
EXPECT_EQ(errno, ENOENT);
}
static int handled = -1;
static void signal_handler(int signal)
{
if (write(handled, "c", 1) != 1)
perror("write from signal");
}
TEST(user_notification_signal)
{
pid_t pid;
long ret;
int status, listener, sk_pair[2];
struct seccomp_notif req = {};
struct seccomp_notif_resp resp = {};
char c;
ASSERT_EQ(socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, sk_pair), 0);
listener = user_trap_syscall(__NR_gettid,
SECCOMP_FILTER_FLAG_NEW_LISTENER);
EXPECT_GE(listener, 0);
pid = fork();
ASSERT_GE(pid, 0);
if (pid == 0) {
close(sk_pair[0]);
handled = sk_pair[1];
if (signal(SIGUSR1, signal_handler) == SIG_ERR) {
perror("signal");
exit(1);
}
/*
* ERESTARTSYS behavior is a bit hard to test, because we need
* to rely on a signal that has not yet been handled. Let's at
* least check that the error code gets propagated through, and
* hope that it doesn't break when there is actually a signal :)
*/
ret = syscall(__NR_gettid);
exit(!(ret == -1 && errno == 512));
}
close(sk_pair[1]);
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
EXPECT_EQ(kill(pid, SIGUSR1), 0);
/*
* Make sure the signal really is delivered, which means we're not
* stuck in the user notification code any more and the notification
* should be dead.
*/
EXPECT_EQ(read(sk_pair[0], &c, 1), 1);
resp.id = req.id;
resp.error = -EPERM;
resp.val = 0;
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, &resp), -1);
EXPECT_EQ(errno, ENOENT);
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
resp.id = req.id;
resp.error = -512; /* -ERESTARTSYS */
resp.val = 0;
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, &resp), 0);
EXPECT_EQ(waitpid(pid, &status, 0), pid);
EXPECT_EQ(true, WIFEXITED(status));
EXPECT_EQ(0, WEXITSTATUS(status));
}
TEST(user_notification_closed_listener)
{
pid_t pid;
long ret;
int status, listener;
listener = user_trap_syscall(__NR_getpid,
SECCOMP_FILTER_FLAG_NEW_LISTENER);
EXPECT_GE(listener, 0);
/*
* Check that we get an ENOSYS when the listener is closed.
*/
pid = fork();
ASSERT_GE(pid, 0);
if (pid == 0) {
close(listener);
ret = syscall(__NR_getpid);
exit(ret != -1 && errno != ENOSYS);
}
close(listener);
EXPECT_EQ(waitpid(pid, &status, 0), pid);
EXPECT_EQ(true, WIFEXITED(status));
EXPECT_EQ(0, WEXITSTATUS(status));
}
/*
* Check that a pid in a child namespace still shows up as valid in ours.
*/
TEST(user_notification_child_pid_ns)
{
pid_t pid;
int status, listener;
struct seccomp_notif req = {};
struct seccomp_notif_resp resp = {};
ASSERT_EQ(unshare(CLONE_NEWPID), 0);
listener = user_trap_syscall(__NR_getpid, SECCOMP_FILTER_FLAG_NEW_LISTENER);
ASSERT_GE(listener, 0);
pid = fork();
ASSERT_GE(pid, 0);
if (pid == 0)
exit(syscall(__NR_getpid) != USER_NOTIF_MAGIC);
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
EXPECT_EQ(req.pid, pid);
resp.id = req.id;
resp.error = 0;
resp.val = USER_NOTIF_MAGIC;
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, &resp), 0);
EXPECT_EQ(waitpid(pid, &status, 0), pid);
EXPECT_EQ(true, WIFEXITED(status));
EXPECT_EQ(0, WEXITSTATUS(status));
close(listener);
}
/*
* Check that a pid in a sibling (i.e. unrelated) namespace shows up as 0, i.e.
* invalid.
*/
TEST(user_notification_sibling_pid_ns)
{
pid_t pid, pid2;
int status, listener;
struct seccomp_notif req = {};
struct seccomp_notif_resp resp = {};
listener = user_trap_syscall(__NR_getpid, SECCOMP_FILTER_FLAG_NEW_LISTENER);
ASSERT_GE(listener, 0);
pid = fork();
ASSERT_GE(pid, 0);
if (pid == 0) {
ASSERT_EQ(unshare(CLONE_NEWPID), 0);
pid2 = fork();
ASSERT_GE(pid2, 0);
if (pid2 == 0)
exit(syscall(__NR_getpid) != USER_NOTIF_MAGIC);
EXPECT_EQ(waitpid(pid2, &status, 0), pid2);
EXPECT_EQ(true, WIFEXITED(status));
EXPECT_EQ(0, WEXITSTATUS(status));
exit(WEXITSTATUS(status));
}
/* Create the sibling ns, and sibling in it. */
EXPECT_EQ(unshare(CLONE_NEWPID), 0);
EXPECT_EQ(errno, 0);
pid2 = fork();
EXPECT_GE(pid2, 0);
if (pid2 == 0) {
ASSERT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
/*
* The pid should be 0, i.e. the task is in some namespace that
* we can't "see".
*/
ASSERT_EQ(req.pid, 0);
resp.id = req.id;
resp.error = 0;
resp.val = USER_NOTIF_MAGIC;
ASSERT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, &resp), 0);
exit(0);
}
close(listener);
EXPECT_EQ(waitpid(pid, &status, 0), pid);
EXPECT_EQ(true, WIFEXITED(status));
EXPECT_EQ(0, WEXITSTATUS(status));
EXPECT_EQ(waitpid(pid2, &status, 0), pid2);
EXPECT_EQ(true, WIFEXITED(status));
EXPECT_EQ(0, WEXITSTATUS(status));
}
TEST(user_notification_fault_recv)
{
pid_t pid;
int status, listener;
struct seccomp_notif req = {};
struct seccomp_notif_resp resp = {};
listener = user_trap_syscall(__NR_getpid, SECCOMP_FILTER_FLAG_NEW_LISTENER);
ASSERT_GE(listener, 0);
pid = fork();
ASSERT_GE(pid, 0);
if (pid == 0)
exit(syscall(__NR_getpid) != USER_NOTIF_MAGIC);
/* Do a bad recv() */
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, NULL), -1);
EXPECT_EQ(errno, EFAULT);
/* We should still be able to receive this notification, though. */
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req), 0);
EXPECT_EQ(req.pid, pid);
resp.id = req.id;
resp.error = 0;
resp.val = USER_NOTIF_MAGIC;
EXPECT_EQ(ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, &resp), 0);
EXPECT_EQ(waitpid(pid, &status, 0), pid);
EXPECT_EQ(true, WIFEXITED(status));
EXPECT_EQ(0, WEXITSTATUS(status));
}
TEST(seccomp_get_notif_sizes)
{
struct seccomp_notif_sizes sizes;
EXPECT_EQ(seccomp(SECCOMP_GET_NOTIF_SIZES, 0, &sizes), 0);
EXPECT_EQ(sizes.seccomp_notif, sizeof(struct seccomp_notif));
EXPECT_EQ(sizes.seccomp_notif_resp, sizeof(struct seccomp_notif_resp));
}
/*
* TODO:
* - add microbenchmarks