+// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/kernel/signal.c
*
#include <linux/compiler.h>
#include <linux/posix-timers.h>
#include <linux/livepatch.h>
+#include <linux/cgroup.h>
+#include <linux/audit.h>
#define CREATE_TRACE_POINTS
#include <trace/events/signal.h>
#include <asm/unistd.h>
#include <asm/siginfo.h>
#include <asm/cacheflush.h>
-#include "audit.h" /* audit_signal_info() */
/*
* SLAB caches for signal bits.
static bool recalc_sigpending_tsk(struct task_struct *t)
{
- if ((t->jobctl & JOBCTL_PENDING_MASK) ||
+ if ((t->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) ||
PENDING(&t->pending, &t->blocked) ||
- PENDING(&t->signal->shared_pending, &t->blocked)) {
+ PENDING(&t->signal->shared_pending, &t->blocked) ||
+ cgroup_task_frozen(t)) {
set_tsk_thread_flag(t, TIF_SIGPENDING);
return true;
}
*/
if (!sid || sid == task_session(current))
break;
+ /* fall through */
default:
return -EPERM;
}
return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
}
-#ifdef CONFIG_USER_NS
-static inline void userns_fixup_signal_uid(struct kernel_siginfo *info, struct task_struct *t)
-{
- if (current_user_ns() == task_cred_xxx(t, user_ns))
- return;
-
- if (SI_FROMKERNEL(info))
- return;
-
- rcu_read_lock();
- info->si_uid = from_kuid_munged(task_cred_xxx(t, user_ns),
- make_kuid(current_user_ns(), info->si_uid));
- rcu_read_unlock();
-}
-#else
-static inline void userns_fixup_signal_uid(struct kernel_siginfo *info, struct task_struct *t)
-{
- return;
-}
-#endif
-
static int __send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
- enum pid_type type, int from_ancestor_ns)
+ enum pid_type type, bool force)
{
struct sigpending *pending;
struct sigqueue *q;
assert_spin_locked(&t->sighand->siglock);
result = TRACE_SIGNAL_IGNORED;
- if (!prepare_signal(sig, t,
- from_ancestor_ns || (info == SEND_SIG_PRIV)))
+ if (!prepare_signal(sig, t, force))
goto ret;
pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
q->info.si_code = SI_USER;
q->info.si_pid = task_tgid_nr_ns(current,
task_active_pid_ns(t));
- q->info.si_uid = from_kuid_munged(current_user_ns(), current_uid());
+ rcu_read_lock();
+ q->info.si_uid =
+ from_kuid_munged(task_cred_xxx(t, user_ns),
+ current_uid());
+ rcu_read_unlock();
break;
case (unsigned long) SEND_SIG_PRIV:
clear_siginfo(&q->info);
break;
default:
copy_siginfo(&q->info, info);
- if (from_ancestor_ns)
- q->info.si_pid = 0;
break;
}
-
- userns_fixup_signal_uid(&q->info, t);
-
- } else if (!is_si_special(info)) {
- if (sig >= SIGRTMIN && info->si_code != SI_USER) {
- /*
- * Queue overflow, abort. We may abort if the
- * signal was rt and sent by user using something
- * other than kill().
- */
- result = TRACE_SIGNAL_OVERFLOW_FAIL;
- ret = -EAGAIN;
- goto ret;
- } else {
- /*
- * This is a silent loss of information. We still
- * send the signal, but the *info bits are lost.
- */
- result = TRACE_SIGNAL_LOSE_INFO;
- }
+ } else if (!is_si_special(info) &&
+ sig >= SIGRTMIN && info->si_code != SI_USER) {
+ /*
+ * Queue overflow, abort. We may abort if the
+ * signal was rt and sent by user using something
+ * other than kill().
+ */
+ result = TRACE_SIGNAL_OVERFLOW_FAIL;
+ ret = -EAGAIN;
+ goto ret;
+ } else {
+ /*
+ * This is a silent loss of information. We still
+ * send the signal, but the *info bits are lost.
+ */
+ result = TRACE_SIGNAL_LOSE_INFO;
}
out_set:
return ret;
}
+static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
+{
+ bool ret = false;
+ switch (siginfo_layout(info->si_signo, info->si_code)) {
+ case SIL_KILL:
+ case SIL_CHLD:
+ case SIL_RT:
+ ret = true;
+ break;
+ case SIL_TIMER:
+ case SIL_POLL:
+ case SIL_FAULT:
+ case SIL_FAULT_MCEERR:
+ case SIL_FAULT_BNDERR:
+ case SIL_FAULT_PKUERR:
+ case SIL_SYS:
+ ret = false;
+ break;
+ }
+ return ret;
+}
+
static int send_signal(int sig, struct kernel_siginfo *info, struct task_struct *t,
enum pid_type type)
{
- int from_ancestor_ns = 0;
+ /* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
+ bool force = false;
-#ifdef CONFIG_PID_NS
- from_ancestor_ns = si_fromuser(info) &&
- !task_pid_nr_ns(current, task_active_pid_ns(t));
-#endif
+ if (info == SEND_SIG_NOINFO) {
+ /* Force if sent from an ancestor pid namespace */
+ force = !task_pid_nr_ns(current, task_active_pid_ns(t));
+ } else if (info == SEND_SIG_PRIV) {
+ /* Don't ignore kernel generated signals */
+ force = true;
+ } else if (has_si_pid_and_uid(info)) {
+ /* SIGKILL and SIGSTOP is special or has ids */
+ struct user_namespace *t_user_ns;
- return __send_signal(sig, info, t, type, from_ancestor_ns);
+ rcu_read_lock();
+ t_user_ns = task_cred_xxx(t, user_ns);
+ if (current_user_ns() != t_user_ns) {
+ kuid_t uid = make_kuid(current_user_ns(), info->si_uid);
+ info->si_uid = from_kuid_munged(t_user_ns, uid);
+ }
+ rcu_read_unlock();
+
+ /* A kernel generated signal? */
+ force = (info->si_code == SI_KERNEL);
+
+ /* From an ancestor pid namespace? */
+ if (!task_pid_nr_ns(current, task_active_pid_ns(t))) {
+ info->si_pid = 0;
+ force = true;
+ }
+ }
+ return __send_signal(sig, info, t, type, force);
}
static void print_fatal_signal(int signr)
* We don't want to have recursive SIGSEGV's etc, for example,
* that is why we also clear SIGNAL_UNKILLABLE.
*/
-int
-force_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *t)
+static int
+force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
{
unsigned long int flags;
int ret, blocked, ignored;
struct k_sigaction *action;
+ int sig = info->si_signo;
spin_lock_irqsave(&t->sighand->siglock, flags);
action = &t->sighand->action[sig-1];
return ret;
}
+int force_sig_info(struct kernel_siginfo *info)
+{
+ return force_sig_info_to_task(info, current);
+}
+
/*
* Nuke all other threads in the group.
*/
uid_eq(cred->uid, pcred->uid);
}
-/* like kill_pid_info(), but doesn't use uid/euid of "current" */
-int kill_pid_info_as_cred(int sig, struct kernel_siginfo *info, struct pid *pid,
- const struct cred *cred)
+/*
+ * The usb asyncio usage of siginfo is wrong. The glibc support
+ * for asyncio which uses SI_ASYNCIO assumes the layout is SIL_RT.
+ * AKA after the generic fields:
+ * kernel_pid_t si_pid;
+ * kernel_uid32_t si_uid;
+ * sigval_t si_value;
+ *
+ * Unfortunately when usb generates SI_ASYNCIO it assumes the layout
+ * after the generic fields is:
+ * void __user *si_addr;
+ *
+ * This is a practical problem when there is a 64bit big endian kernel
+ * and a 32bit userspace. As the 32bit address will encoded in the low
+ * 32bits of the pointer. Those low 32bits will be stored at higher
+ * address than appear in a 32 bit pointer. So userspace will not
+ * see the address it was expecting for it's completions.
+ *
+ * There is nothing in the encoding that can allow
+ * copy_siginfo_to_user32 to detect this confusion of formats, so
+ * handle this by requiring the caller of kill_pid_usb_asyncio to
+ * notice when this situration takes place and to store the 32bit
+ * pointer in sival_int, instead of sival_addr of the sigval_t addr
+ * parameter.
+ */
+int kill_pid_usb_asyncio(int sig, int errno, sigval_t addr,
+ struct pid *pid, const struct cred *cred)
{
- int ret = -EINVAL;
+ struct kernel_siginfo info;
struct task_struct *p;
unsigned long flags;
+ int ret = -EINVAL;
+
+ clear_siginfo(&info);
+ info.si_signo = sig;
+ info.si_errno = errno;
+ info.si_code = SI_ASYNCIO;
+ *((sigval_t *)&info.si_pid) = addr;
if (!valid_signal(sig))
return ret;
ret = -ESRCH;
goto out_unlock;
}
- if (si_fromuser(info) && !kill_as_cred_perm(cred, p)) {
+ if (!kill_as_cred_perm(cred, p)) {
ret = -EPERM;
goto out_unlock;
}
- ret = security_task_kill(p, info, sig, cred);
+ ret = security_task_kill(p, &info, sig, cred);
if (ret)
goto out_unlock;
if (sig) {
if (lock_task_sighand(p, &flags)) {
- ret = __send_signal(sig, info, p, PIDTYPE_TGID, 0);
+ ret = __send_signal(sig, &info, p, PIDTYPE_TGID, false);
unlock_task_sighand(p, &flags);
} else
ret = -ESRCH;
rcu_read_unlock();
return ret;
}
-EXPORT_SYMBOL_GPL(kill_pid_info_as_cred);
+EXPORT_SYMBOL_GPL(kill_pid_usb_asyncio);
/*
* kill_something_info() interprets pid in interesting ways just like kill(2).
}
EXPORT_SYMBOL(send_sig);
-void force_sig(int sig, struct task_struct *p)
+void force_sig(int sig)
{
- force_sig_info(sig, SEND_SIG_PRIV, p);
+ struct kernel_siginfo info;
+
+ clear_siginfo(&info);
+ info.si_signo = sig;
+ info.si_errno = 0;
+ info.si_code = SI_KERNEL;
+ info.si_pid = 0;
+ info.si_uid = 0;
+ force_sig_info(&info);
}
EXPORT_SYMBOL(force_sig);
* the problem was already a SIGSEGV, we'll want to
* make sure we don't even try to deliver the signal..
*/
-void force_sigsegv(int sig, struct task_struct *p)
+void force_sigsegv(int sig)
{
+ struct task_struct *p = current;
+
if (sig == SIGSEGV) {
unsigned long flags;
spin_lock_irqsave(&p->sighand->siglock, flags);
p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
spin_unlock_irqrestore(&p->sighand->siglock, flags);
}
- force_sig(SIGSEGV, p);
+ force_sig(SIGSEGV);
}
-int force_sig_fault(int sig, int code, void __user *addr
+int force_sig_fault_to_task(int sig, int code, void __user *addr
___ARCH_SI_TRAPNO(int trapno)
___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)
, struct task_struct *t)
info.si_flags = flags;
info.si_isr = isr;
#endif
- return force_sig_info(info.si_signo, &info, t);
+ return force_sig_info_to_task(&info, t);
+}
+
+int force_sig_fault(int sig, int code, void __user *addr
+ ___ARCH_SI_TRAPNO(int trapno)
+ ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr))
+{
+ return force_sig_fault_to_task(sig, code, addr
+ ___ARCH_SI_TRAPNO(trapno)
+ ___ARCH_SI_IA64(imm, flags, isr), current);
}
int send_sig_fault(int sig, int code, void __user *addr
return send_sig_info(info.si_signo, &info, t);
}
-int force_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
+int force_sig_mceerr(int code, void __user *addr, short lsb)
{
struct kernel_siginfo info;
info.si_code = code;
info.si_addr = addr;
info.si_addr_lsb = lsb;
- return force_sig_info(info.si_signo, &info, t);
+ return force_sig_info(&info);
}
int send_sig_mceerr(int code, void __user *addr, short lsb, struct task_struct *t)
info.si_addr = addr;
info.si_lower = lower;
info.si_upper = upper;
- return force_sig_info(info.si_signo, &info, current);
+ return force_sig_info(&info);
}
#ifdef SEGV_PKUERR
info.si_code = SEGV_PKUERR;
info.si_addr = addr;
info.si_pkey = pkey;
- return force_sig_info(info.si_signo, &info, current);
+ return force_sig_info(&info);
}
#endif
info.si_errno = errno;
info.si_code = TRAP_HWBKPT;
info.si_addr = addr;
- return force_sig_info(info.si_signo, &info, current);
+ return force_sig_info(&info);
}
int kill_pgrp(struct pid *pid, int sig, int priv)
return ret;
}
+static void do_notify_pidfd(struct task_struct *task)
+{
+ struct pid *pid;
+
+ pid = task_pid(task);
+ wake_up_all(&pid->wait_pidfd);
+}
+
/*
* Let a parent know about the death of a child.
* For a stopped/continued status change, use do_notify_parent_cldstop instead.
BUG_ON(!tsk->ptrace &&
(tsk->group_leader != tsk || !thread_group_empty(tsk)));
+ /* Wake up all pidfd waiters */
+ do_notify_pidfd(tsk);
+
if (sig != SIGCHLD) {
/*
* This is only possible if parent == real_parent.
preempt_disable();
read_unlock(&tasklist_lock);
preempt_enable_no_resched();
+ cgroup_enter_frozen();
freezable_schedule();
+ cgroup_leave_frozen(true);
} else {
/*
* By the time we got the lock, our tracer went away.
}
/* Now we don't run again until woken by SIGCONT or SIGKILL */
+ cgroup_enter_frozen();
freezable_schedule();
return true;
} else {
}
}
+/**
+ * do_freezer_trap - handle the freezer jobctl trap
+ *
+ * Puts the task into frozen state, if only the task is not about to quit.
+ * In this case it drops JOBCTL_TRAP_FREEZE.
+ *
+ * CONTEXT:
+ * Must be called with @current->sighand->siglock held,
+ * which is always released before returning.
+ */
+static void do_freezer_trap(void)
+ __releases(¤t->sighand->siglock)
+{
+ /*
+ * If there are other trap bits pending except JOBCTL_TRAP_FREEZE,
+ * let's make another loop to give it a chance to be handled.
+ * In any case, we'll return back.
+ */
+ if ((current->jobctl & (JOBCTL_PENDING_MASK | JOBCTL_TRAP_FREEZE)) !=
+ JOBCTL_TRAP_FREEZE) {
+ spin_unlock_irq(¤t->sighand->siglock);
+ return;
+ }
+
+ /*
+ * Now we're sure that there is no pending fatal signal and no
+ * pending traps. Clear TIF_SIGPENDING to not get out of schedule()
+ * immediately (if there is a non-fatal signal pending), and
+ * put the task into sleep.
+ */
+ __set_current_state(TASK_INTERRUPTIBLE);
+ clear_thread_flag(TIF_SIGPENDING);
+ spin_unlock_irq(¤t->sighand->siglock);
+ cgroup_enter_frozen();
+ freezable_schedule();
+}
+
static int ptrace_signal(int signr, kernel_siginfo_t *info)
{
/*
if (signal_group_exit(signal)) {
ksig->info.si_signo = signr = SIGKILL;
sigdelset(¤t->pending.signal, SIGKILL);
+ trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
+ &sighand->action[SIGKILL - 1]);
recalc_sigpending();
goto fatal;
}
do_signal_stop(0))
goto relock;
- if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
- do_jobctl_trap();
+ if (unlikely(current->jobctl &
+ (JOBCTL_TRAP_MASK | JOBCTL_TRAP_FREEZE))) {
+ if (current->jobctl & JOBCTL_TRAP_MASK) {
+ do_jobctl_trap();
+ spin_unlock_irq(&sighand->siglock);
+ } else if (current->jobctl & JOBCTL_TRAP_FREEZE)
+ do_freezer_trap();
+
+ goto relock;
+ }
+
+ /*
+ * If the task is leaving the frozen state, let's update
+ * cgroup counters and reset the frozen bit.
+ */
+ if (unlikely(cgroup_task_frozen(current))) {
spin_unlock_irq(&sighand->siglock);
+ cgroup_leave_frozen(false);
goto relock;
}
fatal:
spin_unlock_irq(&sighand->siglock);
+ if (unlikely(cgroup_task_frozen(current)))
+ cgroup_leave_frozen(true);
/*
* Anything else is fatal, maybe with a core dump.
void signal_setup_done(int failed, struct ksignal *ksig, int stepping)
{
if (failed)
- force_sigsegv(ksig->sig, current);
+ force_sigsegv(ksig->sig);
else
signal_delivered(ksig, stepping);
}
*
* This is useful for syscalls such as ppoll, pselect, io_pgetevents and
* epoll_pwait where a new sigmask is passed from userland for the syscalls.
+ *
+ * Note that it does set_restore_sigmask() in advance, so it must be always
+ * paired with restore_saved_sigmask_unless() before return from syscall.
*/
-int set_user_sigmask(const sigset_t __user *usigmask, sigset_t *set,
- sigset_t *oldset, size_t sigsetsize)
+int set_user_sigmask(const sigset_t __user *umask, size_t sigsetsize)
{
- if (!usigmask)
- return 0;
+ sigset_t kmask;
+ if (!umask)
+ return 0;
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
- if (copy_from_user(set, usigmask, sizeof(sigset_t)))
+ if (copy_from_user(&kmask, umask, sizeof(sigset_t)))
return -EFAULT;
- *oldset = current->blocked;
- set_current_blocked(set);
+ set_restore_sigmask();
+ current->saved_sigmask = current->blocked;
+ set_current_blocked(&kmask);
return 0;
}
-EXPORT_SYMBOL(set_user_sigmask);
#ifdef CONFIG_COMPAT
-int set_compat_user_sigmask(const compat_sigset_t __user *usigmask,
- sigset_t *set, sigset_t *oldset,
+int set_compat_user_sigmask(const compat_sigset_t __user *umask,
size_t sigsetsize)
{
- if (!usigmask)
- return 0;
+ sigset_t kmask;
+ if (!umask)
+ return 0;
if (sigsetsize != sizeof(compat_sigset_t))
return -EINVAL;
- if (get_compat_sigset(set, usigmask))
+ if (get_compat_sigset(&kmask, umask))
return -EFAULT;
- *oldset = current->blocked;
- set_current_blocked(set);
+ set_restore_sigmask();
+ current->saved_sigmask = current->blocked;
+ set_current_blocked(&kmask);
return 0;
}
-EXPORT_SYMBOL(set_compat_user_sigmask);
#endif
-/*
- * restore_user_sigmask:
- * usigmask: sigmask passed in from userland.
- * sigsaved: saved sigmask when the syscall started and changed the sigmask to
- * usigmask.
- *
- * This is useful for syscalls such as ppoll, pselect, io_pgetevents and
- * epoll_pwait where a new sigmask is passed in from userland for the syscalls.
- */
-void restore_user_sigmask(const void __user *usigmask, sigset_t *sigsaved)
-{
-
- if (!usigmask)
- return;
- /*
- * When signals are pending, do not restore them here.
- * Restoring sigmask here can lead to delivering signals that the above
- * syscalls are intended to block because of the sigmask passed in.
- */
- if (signal_pending(current)) {
- current->saved_sigmask = *sigsaved;
- set_restore_sigmask();
- return;
- }
-
- /*
- * This is needed because the fast syscall return path does not restore
- * saved_sigmask when signals are not pending.
- */
- set_current_blocked(sigsaved);
-}
-EXPORT_SYMBOL(restore_user_sigmask);
-
/**
* sys_rt_sigprocmask - change the list of currently blocked signals
* @how: whether to add, remove, or set signals
return kill_something_info(sig, &info, pid);
}
-#ifdef CONFIG_PROC_FS
/*
* Verify that the signaler and signalee either are in the same pid namespace
* or that the signaler's pid namespace is an ancestor of the signalee's pid
return copy_siginfo_from_user(kinfo, info);
}
+static struct pid *pidfd_to_pid(const struct file *file)
+{
+ if (file->f_op == &pidfd_fops)
+ return file->private_data;
+
+ return tgid_pidfd_to_pid(file);
+}
+
/**
- * sys_pidfd_send_signal - send a signal to a process through a task file
- * descriptor
- * @pidfd: the file descriptor of the process
- * @sig: signal to be sent
- * @info: the signal info
- * @flags: future flags to be passed
+ * sys_pidfd_send_signal - Signal a process through a pidfd
+ * @pidfd: file descriptor of the process
+ * @sig: signal to send
+ * @info: signal info
+ * @flags: future flags
*
* The syscall currently only signals via PIDTYPE_PID which covers
* kill(<positive-pid>, <signal>. It does not signal threads or process
return -EBADF;
/* Is this a pidfd? */
- pid = tgid_pidfd_to_pid(f.file);
+ pid = pidfd_to_pid(f.file);
if (IS_ERR(pid)) {
ret = PTR_ERR(pid);
goto err;
fdput(f);
return ret;
}
-#endif /* CONFIG_PROC_FS */
static int
do_send_specific(pid_t tgid, pid_t pid, int sig, struct kernel_siginfo *info)
CHECK_OFFSET(si_syscall);
CHECK_OFFSET(si_arch);
#undef CHECK_OFFSET
+
+ /* usb asyncio */
+ BUILD_BUG_ON(offsetof(struct siginfo, si_pid) !=
+ offsetof(struct siginfo, si_addr));
+ if (sizeof(int) == sizeof(void __user *)) {
+ BUILD_BUG_ON(sizeof_field(struct siginfo, si_pid) !=
+ sizeof(void __user *));
+ } else {
+ BUILD_BUG_ON((sizeof_field(struct siginfo, si_pid) +
+ sizeof_field(struct siginfo, si_uid)) !=
+ sizeof(void __user *));
+ BUILD_BUG_ON(offsetofend(struct siginfo, si_pid) !=
+ offsetof(struct siginfo, si_uid));
+ }
+#ifdef CONFIG_COMPAT
+ BUILD_BUG_ON(offsetof(struct compat_siginfo, si_pid) !=
+ offsetof(struct compat_siginfo, si_addr));
+ BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
+ sizeof(compat_uptr_t));
+ BUILD_BUG_ON(sizeof_field(struct compat_siginfo, si_pid) !=
+ sizeof_field(struct siginfo, si_pid));
+#endif
}
void __init signals_init(void)
projects / linux.git / blobdiff