kernel/compat.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  *  linux/kernel/compat.c
  *
  *  Kernel compatibililty routines for e.g. 32 bit syscall support
  *  on 64 bit kernels.
  *
  *  Copyright (C) 2002-2003 Stephen Rothwell, IBM Corporation
  */

 #include <linux/linkage.h>
 #include <linux/compat.h>
 #include <linux/errno.h>
 #include <linux/time.h>
 #include <linux/signal.h>
 #include <linux/sched.h>	/* for MAX_SCHEDULE_TIMEOUT */
 #include <linux/syscalls.h>
 #include <linux/unistd.h>
 #include <linux/security.h>
 #include <linux/export.h>
 #include <linux/migrate.h>
 #include <linux/posix-timers.h>
 #include <linux/times.h>
 #include <linux/ptrace.h>
 #include <linux/gfp.h>

 #include <linux/uaccess.h>

 #ifdef __ARCH_WANT_SYS_SIGPROCMASK

 /*
  * sys_sigprocmask SIG_SETMASK sets the first (compat) word of the
  * blocked set of signals to the supplied signal set
  */
 static inline void compat_sig_setmask(sigset_t *blocked, compat_sigset_word set)
 {
 	memcpy(blocked->sig, &set, sizeof(set));
 }

 COMPAT_SYSCALL_DEFINE3(sigprocmask, int, how,
 		       compat_old_sigset_t __user *, nset,
 		       compat_old_sigset_t __user *, oset)
 {
 	old_sigset_t old_set, new_set;
 	sigset_t new_blocked;

 	old_set = current->blocked.sig[0];

 	if (nset) {
 		if (get_user(new_set, nset))
 			return -EFAULT;
 		new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));

 		new_blocked = current->blocked;

 		switch (how) {
 		case SIG_BLOCK:
 			sigaddsetmask(&new_blocked, new_set);
 			break;
 		case SIG_UNBLOCK:
 			sigdelsetmask(&new_blocked, new_set);
 			break;
 		case SIG_SETMASK:
 			compat_sig_setmask(&new_blocked, new_set);
 			break;
 		default:
 			return -EINVAL;
 		}

 		set_current_blocked(&new_blocked);
 	}

 	if (oset) {
 		if (put_user(old_set, oset))
 			return -EFAULT;
 	}

 	return 0;
 }

 #endif

 int put_compat_rusage(const struct rusage *r, struct compat_rusage __user *ru)
 {
 	struct compat_rusage r32;
 	memset(&r32, 0, sizeof(r32));
 	r32.ru_utime.tv_sec = r->ru_utime.tv_sec;
 	r32.ru_utime.tv_usec = r->ru_utime.tv_usec;
 	r32.ru_stime.tv_sec = r->ru_stime.tv_sec;
 	r32.ru_stime.tv_usec = r->ru_stime.tv_usec;
 	r32.ru_maxrss = r->ru_maxrss;
 	r32.ru_ixrss = r->ru_ixrss;
 	r32.ru_idrss = r->ru_idrss;
 	r32.ru_isrss = r->ru_isrss;
 	r32.ru_minflt = r->ru_minflt;
 	r32.ru_majflt = r->ru_majflt;
 	r32.ru_nswap = r->ru_nswap;
 	r32.ru_inblock = r->ru_inblock;
 	r32.ru_oublock = r->ru_oublock;
 	r32.ru_msgsnd = r->ru_msgsnd;
 	r32.ru_msgrcv = r->ru_msgrcv;
 	r32.ru_nsignals = r->ru_nsignals;
 	r32.ru_nvcsw = r->ru_nvcsw;
 	r32.ru_nivcsw = r->ru_nivcsw;
 	if (copy_to_user(ru, &r32, sizeof(r32)))
 		return -EFAULT;
 	return 0;
 }

 static int compat_get_user_cpu_mask(compat_ulong_t __user *user_mask_ptr,
 				    unsigned len, struct cpumask *new_mask)
 {
 	unsigned long *k;

 	if (len < cpumask_size())
 		memset(new_mask, 0, cpumask_size());
 	else if (len > cpumask_size())
 		len = cpumask_size();

 	k = cpumask_bits(new_mask);
 	return compat_get_bitmap(k, user_mask_ptr, len * 8);
 }

 COMPAT_SYSCALL_DEFINE3(sched_setaffinity, compat_pid_t, pid,
 		       unsigned int, len,
 		       compat_ulong_t __user *, user_mask_ptr)
 {
 	cpumask_var_t new_mask;
 	int retval;

 	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
 		return -ENOMEM;

 	retval = compat_get_user_cpu_mask(user_mask_ptr, len, new_mask);
 	if (retval)
 		goto out;

 	retval = sched_setaffinity(pid, new_mask);
 out:
 	free_cpumask_var(new_mask);
 	return retval;
 }

 COMPAT_SYSCALL_DEFINE3(sched_getaffinity, compat_pid_t,  pid, unsigned int, len,
 		       compat_ulong_t __user *, user_mask_ptr)
 {
 	int ret;
 	cpumask_var_t mask;

 	if ((len * BITS_PER_BYTE) < nr_cpu_ids)
 		return -EINVAL;
 	if (len & (sizeof(compat_ulong_t)-1))
 		return -EINVAL;

 	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
 		return -ENOMEM;

 	ret = sched_getaffinity(pid, mask);
 	if (ret == 0) {
 		unsigned int retlen = min(len, cpumask_size());

 		if (compat_put_bitmap(user_mask_ptr, cpumask_bits(mask), retlen * 8))
 			ret = -EFAULT;
 		else
 			ret = retlen;
 	}
 	free_cpumask_var(mask);

 	return ret;
 }

 /*
  * We currently only need the following fields from the sigevent
  * structure: sigev_value, sigev_signo, sig_notify and (sometimes
  * sigev_notify_thread_id).  The others are handled in user mode.
  * We also assume that copying sigev_value.sival_int is sufficient
  * to keep all the bits of sigev_value.sival_ptr intact.
  */
 int get_compat_sigevent(struct sigevent *event,
 		const struct compat_sigevent __user *u_event)
 {
 	memset(event, 0, sizeof(*event));
 	return (!access_ok(u_event, sizeof(*u_event)) ||
 		__get_user(event->sigev_value.sival_int,
 			&u_event->sigev_value.sival_int) ||
 		__get_user(event->sigev_signo, &u_event->sigev_signo) ||
 		__get_user(event->sigev_notify, &u_event->sigev_notify) ||
 		__get_user(event->sigev_notify_thread_id,
 			&u_event->sigev_notify_thread_id))
 		? -EFAULT : 0;
 }

 long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
 		       unsigned long bitmap_size)
 {
 	unsigned long nr_compat_longs;

 	/* align bitmap up to nearest compat_long_t boundary */
 	bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
 	nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);

 	if (!user_read_access_begin(umask, bitmap_size / 8))
 		return -EFAULT;

 	while (nr_compat_longs > 1) {
 		compat_ulong_t l1, l2;
 		unsafe_get_user(l1, umask++, Efault);
 		unsafe_get_user(l2, umask++, Efault);
 		*mask++ = ((unsigned long)l2 << BITS_PER_COMPAT_LONG) | l1;
 		nr_compat_longs -= 2;
 	}
 	if (nr_compat_longs)
 		unsafe_get_user(*mask, umask++, Efault);
 	user_read_access_end();
 	return 0;

 Efault:
 	user_read_access_end();
 	return -EFAULT;
 }

 long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
 		       unsigned long bitmap_size)
 {
 	unsigned long nr_compat_longs;

 	/* align bitmap up to nearest compat_long_t boundary */
 	bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
 	nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);

 	if (!user_write_access_begin(umask, bitmap_size / 8))
 		return -EFAULT;

 	while (nr_compat_longs > 1) {
 		unsigned long m = *mask++;
 		unsafe_put_user((compat_ulong_t)m, umask++, Efault);
 		unsafe_put_user(m >> BITS_PER_COMPAT_LONG, umask++, Efault);
 		nr_compat_longs -= 2;
 	}
 	if (nr_compat_longs)
 		unsafe_put_user((compat_ulong_t)*mask, umask++, Efault);
 	user_write_access_end();
 	return 0;
 Efault:
 	user_write_access_end();
 	return -EFAULT;
 }

 int
 get_compat_sigset(sigset_t *set, const compat_sigset_t __user *compat)
 {
 #ifdef __BIG_ENDIAN
 	compat_sigset_t v;
 	if (copy_from_user(&v, compat, sizeof(compat_sigset_t)))
 		return -EFAULT;
 	switch (_NSIG_WORDS) {
 	case 4: set->sig[3] = v.sig[6] | (((long)v.sig[7]) << 32 );
 		fallthrough;
 	case 3: set->sig[2] = v.sig[4] | (((long)v.sig[5]) << 32 );
 		fallthrough;
 	case 2: set->sig[1] = v.sig[2] | (((long)v.sig[3]) << 32 );
 		fallthrough;
 	case 1: set->sig[0] = v.sig[0] | (((long)v.sig[1]) << 32 );
 	}
 #else
 	if (copy_from_user(set, compat, sizeof(compat_sigset_t)))
 		return -EFAULT;
 #endif
 	return 0;
 }
 EXPORT_SYMBOL_GPL(get_compat_sigset);

 /*
  * Allocate user-space memory for the duration of a single system call,
  * in order to marshall parameters inside a compat thunk.
  */
 void __user *compat_alloc_user_space(unsigned long len)
 {
 	void __user *ptr;

 	/* If len would occupy more than half of the entire compat space... */
 	if (unlikely(len > (((compat_uptr_t)~0) >> 1)))
 		return NULL;

 	ptr = arch_compat_alloc_user_space(len);

 	if (unlikely(!access_ok(ptr, len)))
 		return NULL;

 	return ptr;
 }
 EXPORT_SYMBOL_GPL(compat_alloc_user_space);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* linux/kernel/compat.c
	*
	* Kernel compatibililty routines for e.g. 32 bit syscall support
	* on 64 bit kernels.
	*
	* Copyright (C) 2002-2003 Stephen Rothwell, IBM Corporation
	*/

	#include <linux/linkage.h>
	#include <linux/compat.h>
	#include <linux/errno.h>
	#include <linux/time.h>
	#include <linux/signal.h>
	#include <linux/sched.h> /* for MAX_SCHEDULE_TIMEOUT */
	#include <linux/syscalls.h>
	#include <linux/unistd.h>
	#include <linux/security.h>
	#include <linux/export.h>
	#include <linux/migrate.h>
	#include <linux/posix-timers.h>
	#include <linux/times.h>
	#include <linux/ptrace.h>
	#include <linux/gfp.h>

	#include <linux/uaccess.h>

	#ifdef __ARCH_WANT_SYS_SIGPROCMASK

	/*
	* sys_sigprocmask SIG_SETMASK sets the first (compat) word of the
	* blocked set of signals to the supplied signal set
	*/
	static inline void compat_sig_setmask(sigset_t *blocked, compat_sigset_word set)
	{
	memcpy(blocked->sig, &set, sizeof(set));
	}

	COMPAT_SYSCALL_DEFINE3(sigprocmask, int, how,
	compat_old_sigset_t __user *, nset,
	compat_old_sigset_t __user *, oset)
	{
	old_sigset_t old_set, new_set;
	sigset_t new_blocked;

	old_set = current->blocked.sig[0];

	if (nset) {
	if (get_user(new_set, nset))
	return -EFAULT;
	new_set &= ~(sigmask(SIGKILL) \| sigmask(SIGSTOP));

	new_blocked = current->blocked;

	switch (how) {
	case SIG_BLOCK:
	sigaddsetmask(&new_blocked, new_set);
	break;
	case SIG_UNBLOCK:
	sigdelsetmask(&new_blocked, new_set);
	break;
	case SIG_SETMASK:
	compat_sig_setmask(&new_blocked, new_set);
	break;
	default:
	return -EINVAL;
	}

	set_current_blocked(&new_blocked);
	}

	if (oset) {
	if (put_user(old_set, oset))
	return -EFAULT;
	}

	return 0;
	}

	#endif

	int put_compat_rusage(const struct rusage r, struct compat_rusage __user ru)
	{
	struct compat_rusage r32;
	memset(&r32, 0, sizeof(r32));
	r32.ru_utime.tv_sec = r->ru_utime.tv_sec;
	r32.ru_utime.tv_usec = r->ru_utime.tv_usec;
	r32.ru_stime.tv_sec = r->ru_stime.tv_sec;
	r32.ru_stime.tv_usec = r->ru_stime.tv_usec;
	r32.ru_maxrss = r->ru_maxrss;
	r32.ru_ixrss = r->ru_ixrss;
	r32.ru_idrss = r->ru_idrss;
	r32.ru_isrss = r->ru_isrss;
	r32.ru_minflt = r->ru_minflt;
	r32.ru_majflt = r->ru_majflt;
	r32.ru_nswap = r->ru_nswap;
	r32.ru_inblock = r->ru_inblock;
	r32.ru_oublock = r->ru_oublock;
	r32.ru_msgsnd = r->ru_msgsnd;
	r32.ru_msgrcv = r->ru_msgrcv;
	r32.ru_nsignals = r->ru_nsignals;
	r32.ru_nvcsw = r->ru_nvcsw;
	r32.ru_nivcsw = r->ru_nivcsw;
	if (copy_to_user(ru, &r32, sizeof(r32)))
	return -EFAULT;
	return 0;
	}

	static int compat_get_user_cpu_mask(compat_ulong_t __user *user_mask_ptr,
	unsigned len, struct cpumask *new_mask)
	{
	unsigned long *k;

	if (len < cpumask_size())
	memset(new_mask, 0, cpumask_size());
	else if (len > cpumask_size())
	len = cpumask_size();

	k = cpumask_bits(new_mask);
	return compat_get_bitmap(k, user_mask_ptr, len * 8);
	}

	COMPAT_SYSCALL_DEFINE3(sched_setaffinity, compat_pid_t, pid,
	unsigned int, len,
	compat_ulong_t __user *, user_mask_ptr)
	{
	cpumask_var_t new_mask;
	int retval;

	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
	return -ENOMEM;

	retval = compat_get_user_cpu_mask(user_mask_ptr, len, new_mask);
	if (retval)
	goto out;

	retval = sched_setaffinity(pid, new_mask);
	out:
	free_cpumask_var(new_mask);
	return retval;
	}

	COMPAT_SYSCALL_DEFINE3(sched_getaffinity, compat_pid_t, pid, unsigned int, len,
	compat_ulong_t __user *, user_mask_ptr)
	{
	int ret;
	cpumask_var_t mask;

	if ((len * BITS_PER_BYTE) < nr_cpu_ids)
	return -EINVAL;
	if (len & (sizeof(compat_ulong_t)-1))
	return -EINVAL;

	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
	return -ENOMEM;

	ret = sched_getaffinity(pid, mask);
	if (ret == 0) {
	unsigned int retlen = min(len, cpumask_size());

	if (compat_put_bitmap(user_mask_ptr, cpumask_bits(mask), retlen * 8))
	ret = -EFAULT;
	else
	ret = retlen;
	}
	free_cpumask_var(mask);

	return ret;
	}

	/*
	* We currently only need the following fields from the sigevent
	* structure: sigev_value, sigev_signo, sig_notify and (sometimes
	* sigev_notify_thread_id). The others are handled in user mode.
	* We also assume that copying sigev_value.sival_int is sufficient
	* to keep all the bits of sigev_value.sival_ptr intact.
	*/
	int get_compat_sigevent(struct sigevent *event,
	const struct compat_sigevent __user *u_event)
	{
	memset(event, 0, sizeof(*event));
	return (!access_ok(u_event, sizeof(*u_event)) \|\|
	__get_user(event->sigev_value.sival_int,
	&u_event->sigev_value.sival_int) \|\|
	__get_user(event->sigev_signo, &u_event->sigev_signo) \|\|
	__get_user(event->sigev_notify, &u_event->sigev_notify) \|\|
	__get_user(event->sigev_notify_thread_id,
	&u_event->sigev_notify_thread_id))
	? -EFAULT : 0;
	}

	long compat_get_bitmap(unsigned long mask, const compat_ulong_t __user umask,
	unsigned long bitmap_size)
	{
	unsigned long nr_compat_longs;

	/* align bitmap up to nearest compat_long_t boundary */
	bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
	nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);

	if (!user_read_access_begin(umask, bitmap_size / 8))
	return -EFAULT;

	while (nr_compat_longs > 1) {
	compat_ulong_t l1, l2;
	unsafe_get_user(l1, umask++, Efault);
	unsafe_get_user(l2, umask++, Efault);
	*mask++ = ((unsigned long)l2 << BITS_PER_COMPAT_LONG) \| l1;
	nr_compat_longs -= 2;
	}
	if (nr_compat_longs)
	unsafe_get_user(*mask, umask++, Efault);
	user_read_access_end();
	return 0;

	Efault:
	user_read_access_end();
	return -EFAULT;
	}

	long compat_put_bitmap(compat_ulong_t __user umask, unsigned long mask,
	unsigned long bitmap_size)
	{
	unsigned long nr_compat_longs;

	/* align bitmap up to nearest compat_long_t boundary */
	bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
	nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);

	if (!user_write_access_begin(umask, bitmap_size / 8))
	return -EFAULT;

	while (nr_compat_longs > 1) {
	unsigned long m = *mask++;
	unsafe_put_user((compat_ulong_t)m, umask++, Efault);
	unsafe_put_user(m >> BITS_PER_COMPAT_LONG, umask++, Efault);
	nr_compat_longs -= 2;
	}
	if (nr_compat_longs)
	unsafe_put_user((compat_ulong_t)*mask, umask++, Efault);
	user_write_access_end();
	return 0;
	Efault:
	user_write_access_end();
	return -EFAULT;
	}

	int
	get_compat_sigset(sigset_t set, const compat_sigset_t __user compat)
	{
	#ifdef __BIG_ENDIAN
	compat_sigset_t v;
	if (copy_from_user(&v, compat, sizeof(compat_sigset_t)))
	return -EFAULT;
	switch (_NSIG_WORDS) {
	case 4: set->sig[3] = v.sig[6] \| (((long)v.sig[7]) << 32 );
	fallthrough;
	case 3: set->sig[2] = v.sig[4] \| (((long)v.sig[5]) << 32 );
	fallthrough;
	case 2: set->sig[1] = v.sig[2] \| (((long)v.sig[3]) << 32 );
	fallthrough;
	case 1: set->sig[0] = v.sig[0] \| (((long)v.sig[1]) << 32 );
	}
	#else
	if (copy_from_user(set, compat, sizeof(compat_sigset_t)))
	return -EFAULT;
	#endif
	return 0;
	}
	EXPORT_SYMBOL_GPL(get_compat_sigset);

	/*
	* Allocate user-space memory for the duration of a single system call,
	* in order to marshall parameters inside a compat thunk.
	*/
	void __user *compat_alloc_user_space(unsigned long len)
	{
	void __user *ptr;

	/* If len would occupy more than half of the entire compat space... */
	if (unlikely(len > (((compat_uptr_t)~0) >> 1)))
	return NULL;

	ptr = arch_compat_alloc_user_space(len);

	if (unlikely(!access_ok(ptr, len)))
	return NULL;

	return ptr;
	}
	EXPORT_SYMBOL_GPL(compat_alloc_user_space);