ucopy.c - platform/external/strace - Git at Google

 /*
  * Copyright (c) 1991, 1992 Paul Kranenburg <pk@cs.few.eur.nl>
  * Copyright (c) 1993 Branko Lankester <branko@hacktic.nl>
  * Copyright (c) 1993, 1994, 1995, 1996 Rick Sladkey <jrs@world.std.com>
  * Copyright (c) 1996-1999 Wichert Akkerman <wichert@cistron.nl>
  * Copyright (c) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
  *                     Linux for s390 port by D.J. Barrow
  *                    <barrow_dj@mail.yahoo.com,djbarrow@de.ibm.com>
  * Copyright (c) 1999-2017 The strace developers.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "defs.h"
 #include <sys/uio.h>
 #include <asm/unistd.h>

 #include "scno.h"
 #include "ptrace.h"

 static bool process_vm_readv_not_supported;

 #ifndef HAVE_PROCESS_VM_READV
 /*
  * Need to do this since process_vm_readv() is not yet available in libc.
  * When libc is updated, only "static bool process_vm_readv_not_supported"
  * line remains.
  * The name is different to avoid potential collision with OS headers.
  */
 static ssize_t strace_process_vm_readv(pid_t pid,
 		 const struct iovec *lvec,
 		 unsigned long liovcnt,
 		 const struct iovec *rvec,
 		 unsigned long riovcnt,
 		 unsigned long flags)
 {
 	return syscall(__NR_process_vm_readv,
 		       (long) pid, lvec, liovcnt, rvec, riovcnt, flags);
 }
 # define process_vm_readv strace_process_vm_readv
 #endif /* !HAVE_PROCESS_VM_READV */

 static ssize_t
 vm_read_mem(const pid_t pid, void *const laddr,
 	    const kernel_ulong_t raddr, const size_t len)
 {
 	const unsigned long truncated_raddr = raddr;

 #if SIZEOF_LONG < SIZEOF_KERNEL_LONG_T
 	if (raddr != (kernel_ulong_t) truncated_raddr) {
 		errno = EIO;
 		return -1;
 	}
 #endif

 	const struct iovec local = {
 		.iov_base = laddr,
 		.iov_len = len
 	};
 	const struct iovec remote = {
 		.iov_base = (void *) truncated_raddr,
 		.iov_len = len
 	};

 	const ssize_t rc = process_vm_readv(pid, &local, 1, &remote, 1, 0);
 	if (rc < 0 && errno == ENOSYS)
 		process_vm_readv_not_supported = true;

 	return rc;
 }

 static bool
 tracee_addr_is_invalid(kernel_ulong_t addr)
 {
 	return
 #if ANY_WORDSIZE_LESS_THAN_KERNEL_LONG
 		current_wordsize < sizeof(addr) && addr & ~(kernel_ulong_t) -1U;
 #else
 		false;
 #endif
 }

 /* legacy method of copying from tracee */
 static int
 umoven_peekdata(const int pid, kernel_ulong_t addr, unsigned int len,
 		void *laddr)
 {
 	unsigned int nread = 0;
 	unsigned int residue = addr & (sizeof(long) - 1);

 	while (len) {
 		addr &= -sizeof(long);		/* aligned address */

 		errno = 0;
 		union {
 			long val;
 			char x[sizeof(long)];
 		} u = { .val = ptrace(PTRACE_PEEKDATA, pid, addr, 0) };

 		switch (errno) {
 			case 0:
 				break;
 			case ESRCH: case EINVAL:
 				/* these could be seen if the process is gone */
 				return -1;
 			case EFAULT: case EIO: case EPERM:
 				/* address space is inaccessible */
 				if (nread) {
 					perror_msg("umoven: short read (%u < %u) @0x%" PRI_klx,
 						   nread, nread + len, addr - nread);
 				}
 				return -1;
 			default:
 				/* all the rest is strange and should be reported */
 				perror_msg("umoven: PTRACE_PEEKDATA pid:%d @0x%" PRI_klx,
 					    pid, addr);
 				return -1;
 		}

 		unsigned int m = MIN(sizeof(long) - residue, len);
 		memcpy(laddr, &u.x[residue], m);
 		residue = 0;
 		addr += sizeof(long);
 		laddr += m;
 		nread += m;
 		len -= m;
 	}

 	return 0;
 }

 /*
  * Copy `len' bytes of data from process `pid'
  * at address `addr' to our space at `our_addr'.
  */
 int
 umoven(struct tcb *const tcp, kernel_ulong_t addr, unsigned int len,
        void *const our_addr)
 {
 	if (tracee_addr_is_invalid(addr))
 		return -1;

 	const int pid = tcp->pid;

 	if (process_vm_readv_not_supported)
 		return umoven_peekdata(pid, addr, len, our_addr);

 	int r = vm_read_mem(pid, our_addr, addr, len);
 	if ((unsigned int) r == len)
 		return 0;
 	if (r >= 0) {
 		error_msg("umoven: short read (%u < %u) @0x%" PRI_klx,
 			  (unsigned int) r, len, addr);
 		return -1;
 	}
 	switch (errno) {
 		case ENOSYS:
 		case EPERM:
 			/* try PTRACE_PEEKDATA */
 			return umoven_peekdata(pid, addr, len, our_addr);
 		case ESRCH:
 			/* the process is gone */
 			return -1;
 		case EFAULT: case EIO:
 			/* address space is inaccessible */
 			return -1;
 		default:
 			/* all the rest is strange and should be reported */
 			perror_msg("process_vm_readv: pid:%d @0x%" PRI_klx,
 				    pid, addr);
 			return -1;
 	}
 }

 /*
  * Like umoven_peekdata but make the additional effort of looking
  * for a terminating zero byte.
  */
 static int
 umovestr_peekdata(const int pid, kernel_ulong_t addr, unsigned int len,
 		  void *laddr)
 {
 	unsigned int nread = 0;
 	unsigned int residue = addr & (sizeof(long) - 1);
 	void *const orig_addr = laddr;

 	while (len) {
 		addr &= -sizeof(long);		/* aligned address */

 		errno = 0;
 		union {
 			unsigned long val;
 			char x[sizeof(long)];
 		} u = { .val = ptrace(PTRACE_PEEKDATA, pid, addr, 0) };

 		switch (errno) {
 			case 0:
 				break;
 			case ESRCH: case EINVAL:
 				/* these could be seen if the process is gone */
 				return -1;
 			case EFAULT: case EIO: case EPERM:
 				/* address space is inaccessible */
 				if (nread) {
 					perror_msg("umovestr: short read (%d < %d) @0x%" PRI_klx,
 						   nread, nread + len, addr - nread);
 				}
 				return -1;
 			default:
 				/* all the rest is strange and should be reported */
 				perror_msg("umovestr: PTRACE_PEEKDATA pid:%d @0x%" PRI_klx,
 					   pid, addr);
 				return -1;
 		}

 		unsigned int m = MIN(sizeof(long) - residue, len);
 		memcpy(laddr, &u.x[residue], m);
 		while (residue < sizeof(long))
 			if (u.x[residue++] == '\0')
 				return (laddr - orig_addr) + residue;
 		residue = 0;
 		addr += sizeof(long);
 		laddr += m;
 		nread += m;
 		len -= m;
 	}

 	return 0;
 }

 /*
  * Like `umove' but make the additional effort of looking
  * for a terminating zero byte.
  *
  * Returns < 0 on error, strlen + 1  if NUL was seen,
  * else 0 if len bytes were read but no NUL byte seen.
  *
  * Note: there is no guarantee we won't overwrite some bytes
  * in laddr[] _after_ terminating NUL (but, of course,
  * we never write past laddr[len-1]).
  */
 int
 umovestr(struct tcb *const tcp, kernel_ulong_t addr, unsigned int len,
 	 char *laddr)
 {
 	if (tracee_addr_is_invalid(addr))
 		return -1;

 	const int pid = tcp->pid;

 	if (process_vm_readv_not_supported)
 		return umovestr_peekdata(pid, addr, len, laddr);

 	const size_t page_size = get_pagesize();
 	const size_t page_mask = page_size - 1;
 	unsigned int nread = 0;

 	while (len) {
 		/*
 		 * Don't cross pages, otherwise we can get EFAULT
 		 * and fail to notice that terminating NUL lies
 		 * in the existing (first) page.
 		 */
 		unsigned int chunk_len = len > page_size ? page_size : len;
 		unsigned int end_in_page = (addr + chunk_len) & page_mask;
 		if (chunk_len > end_in_page) /* crosses to the next page */
 			chunk_len -= end_in_page;

 		int r = vm_read_mem(pid, laddr, addr, chunk_len);
 		if (r > 0) {
 			char *nul_addr = memchr(laddr, '\0', r);

 			if (nul_addr)
 				return (nul_addr - laddr) + 1;
 			addr += r;
 			laddr += r;
 			nread += r;
 			len -= r;
 			continue;
 		}
 		switch (errno) {
 			case ENOSYS:
 			case EPERM:
 				/* try PTRACE_PEEKDATA */
 				if (!nread)
 					return umovestr_peekdata(pid, addr,
 								 len, laddr);
 				/* fall through */
 			case EFAULT: case EIO:
 				/* address space is inaccessible */
 				if (nread)
 					perror_msg("umovestr: short read (%d < %d) @0x%" PRI_klx,
 						   nread, nread + len, addr - nread);
 				return -1;
 			case ESRCH:
 				/* the process is gone */
 				return -1;
 			default:
 				/* all the rest is strange and should be reported */
 				perror_msg("process_vm_readv: pid:%d @0x%" PRI_klx,
 					    pid, addr);
 				return -1;
 		}
 	}

 	return 0;
 }
	/*
	* Copyright (c) 1991, 1992 Paul Kranenburg <pk@cs.few.eur.nl>
	* Copyright (c) 1993 Branko Lankester <branko@hacktic.nl>
	* Copyright (c) 1993, 1994, 1995, 1996 Rick Sladkey <jrs@world.std.com>
	* Copyright (c) 1996-1999 Wichert Akkerman <wichert@cistron.nl>
	* Copyright (c) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
	* Linux for s390 port by D.J. Barrow
	* <barrow_dj@mail.yahoo.com,djbarrow@de.ibm.com>
	* Copyright (c) 1999-2017 The strace developers.
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. The name of the author may not be used to endorse or promote products
	* derived from this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "defs.h"
	#include <sys/uio.h>
	#include <asm/unistd.h>

	#include "scno.h"
	#include "ptrace.h"

	static bool process_vm_readv_not_supported;

	#ifndef HAVE_PROCESS_VM_READV
	/*
	* Need to do this since process_vm_readv() is not yet available in libc.
	* When libc is updated, only "static bool process_vm_readv_not_supported"
	* line remains.
	* The name is different to avoid potential collision with OS headers.
	*/
	static ssize_t strace_process_vm_readv(pid_t pid,
	const struct iovec *lvec,
	unsigned long liovcnt,
	const struct iovec *rvec,
	unsigned long riovcnt,
	unsigned long flags)
	{
	return syscall(__NR_process_vm_readv,
	(long) pid, lvec, liovcnt, rvec, riovcnt, flags);
	}
	# define process_vm_readv strace_process_vm_readv
	#endif /* !HAVE_PROCESS_VM_READV */

	static ssize_t
	vm_read_mem(const pid_t pid, void *const laddr,
	const kernel_ulong_t raddr, const size_t len)
	{
	const unsigned long truncated_raddr = raddr;

	#if SIZEOF_LONG < SIZEOF_KERNEL_LONG_T
	if (raddr != (kernel_ulong_t) truncated_raddr) {
	errno = EIO;
	return -1;
	}
	#endif

	const struct iovec local = {
	.iov_base = laddr,
	.iov_len = len
	};
	const struct iovec remote = {
	.iov_base = (void *) truncated_raddr,
	.iov_len = len
	};

	const ssize_t rc = process_vm_readv(pid, &local, 1, &remote, 1, 0);
	if (rc < 0 && errno == ENOSYS)
	process_vm_readv_not_supported = true;

	return rc;
	}

	static bool
	tracee_addr_is_invalid(kernel_ulong_t addr)
	{
	return
	#if ANY_WORDSIZE_LESS_THAN_KERNEL_LONG
	current_wordsize < sizeof(addr) && addr & ~(kernel_ulong_t) -1U;
	#else
	false;
	#endif
	}

	/* legacy method of copying from tracee */
	static int
	umoven_peekdata(const int pid, kernel_ulong_t addr, unsigned int len,
	void *laddr)
	{
	unsigned int nread = 0;
	unsigned int residue = addr & (sizeof(long) - 1);

	while (len) {
	addr &= -sizeof(long); /* aligned address */

	errno = 0;
	union {
	long val;
	char x[sizeof(long)];
	} u = { .val = ptrace(PTRACE_PEEKDATA, pid, addr, 0) };

	switch (errno) {
	case 0:
	break;
	case ESRCH: case EINVAL:
	/* these could be seen if the process is gone */
	return -1;
	case EFAULT: case EIO: case EPERM:
	/* address space is inaccessible */
	if (nread) {
	perror_msg("umoven: short read (%u < %u) @0x%" PRI_klx,
	nread, nread + len, addr - nread);
	}
	return -1;
	default:
	/* all the rest is strange and should be reported */
	perror_msg("umoven: PTRACE_PEEKDATA pid:%d @0x%" PRI_klx,
	pid, addr);
	return -1;
	}

	unsigned int m = MIN(sizeof(long) - residue, len);
	memcpy(laddr, &u.x[residue], m);
	residue = 0;
	addr += sizeof(long);
	laddr += m;
	nread += m;
	len -= m;
	}

	return 0;
	}

	/*
	* Copy `len' bytes of data from process `pid'
	* at address `addr' to our space at `our_addr'.
	*/
	int
	umoven(struct tcb *const tcp, kernel_ulong_t addr, unsigned int len,
	void *const our_addr)
	{
	if (tracee_addr_is_invalid(addr))
	return -1;

	const int pid = tcp->pid;

	if (process_vm_readv_not_supported)
	return umoven_peekdata(pid, addr, len, our_addr);

	int r = vm_read_mem(pid, our_addr, addr, len);
	if ((unsigned int) r == len)
	return 0;
	if (r >= 0) {
	error_msg("umoven: short read (%u < %u) @0x%" PRI_klx,
	(unsigned int) r, len, addr);
	return -1;
	}
	switch (errno) {
	case ENOSYS:
	case EPERM:
	/* try PTRACE_PEEKDATA */
	return umoven_peekdata(pid, addr, len, our_addr);
	case ESRCH:
	/* the process is gone */
	return -1;
	case EFAULT: case EIO:
	/* address space is inaccessible */
	return -1;
	default:
	/* all the rest is strange and should be reported */
	perror_msg("process_vm_readv: pid:%d @0x%" PRI_klx,
	pid, addr);
	return -1;
	}
	}

	/*
	* Like umoven_peekdata but make the additional effort of looking
	* for a terminating zero byte.
	*/
	static int
	umovestr_peekdata(const int pid, kernel_ulong_t addr, unsigned int len,
	void *laddr)
	{
	unsigned int nread = 0;
	unsigned int residue = addr & (sizeof(long) - 1);
	void *const orig_addr = laddr;

	while (len) {
	addr &= -sizeof(long); /* aligned address */

	errno = 0;
	union {
	unsigned long val;
	char x[sizeof(long)];
	} u = { .val = ptrace(PTRACE_PEEKDATA, pid, addr, 0) };

	switch (errno) {
	case 0:
	break;
	case ESRCH: case EINVAL:
	/* these could be seen if the process is gone */
	return -1;
	case EFAULT: case EIO: case EPERM:
	/* address space is inaccessible */
	if (nread) {
	perror_msg("umovestr: short read (%d < %d) @0x%" PRI_klx,
	nread, nread + len, addr - nread);
	}
	return -1;
	default:
	/* all the rest is strange and should be reported */
	perror_msg("umovestr: PTRACE_PEEKDATA pid:%d @0x%" PRI_klx,
	pid, addr);
	return -1;
	}

	unsigned int m = MIN(sizeof(long) - residue, len);
	memcpy(laddr, &u.x[residue], m);
	while (residue < sizeof(long))
	if (u.x[residue++] == '\0')
	return (laddr - orig_addr) + residue;
	residue = 0;
	addr += sizeof(long);
	laddr += m;
	nread += m;
	len -= m;
	}

	return 0;
	}

	/*
	* Like `umove' but make the additional effort of looking
	* for a terminating zero byte.
	*
	* Returns < 0 on error, strlen + 1 if NUL was seen,
	* else 0 if len bytes were read but no NUL byte seen.
	*
	* Note: there is no guarantee we won't overwrite some bytes
	* in laddr[] _after_ terminating NUL (but, of course,
	* we never write past laddr[len-1]).
	*/
	int
	umovestr(struct tcb *const tcp, kernel_ulong_t addr, unsigned int len,
	char *laddr)
	{
	if (tracee_addr_is_invalid(addr))
	return -1;

	const int pid = tcp->pid;

	if (process_vm_readv_not_supported)
	return umovestr_peekdata(pid, addr, len, laddr);

	const size_t page_size = get_pagesize();
	const size_t page_mask = page_size - 1;
	unsigned int nread = 0;

	while (len) {
	/*
	* Don't cross pages, otherwise we can get EFAULT
	* and fail to notice that terminating NUL lies
	* in the existing (first) page.
	*/
	unsigned int chunk_len = len > page_size ? page_size : len;
	unsigned int end_in_page = (addr + chunk_len) & page_mask;
	if (chunk_len > end_in_page) /* crosses to the next page */
	chunk_len -= end_in_page;

	int r = vm_read_mem(pid, laddr, addr, chunk_len);
	if (r > 0) {
	char *nul_addr = memchr(laddr, '\0', r);

	if (nul_addr)
	return (nul_addr - laddr) + 1;
	addr += r;
	laddr += r;
	nread += r;
	len -= r;
	continue;
	}
	switch (errno) {
	case ENOSYS:
	case EPERM:
	/* try PTRACE_PEEKDATA */
	if (!nread)
	return umovestr_peekdata(pid, addr,
	len, laddr);
	/* fall through */
	case EFAULT: case EIO:
	/* address space is inaccessible */
	if (nread)
	perror_msg("umovestr: short read (%d < %d) @0x%" PRI_klx,
	nread, nread + len, addr - nread);
	return -1;
	case ESRCH:
	/* the process is gone */
	return -1;
	default:
	/* all the rest is strange and should be reported */
	perror_msg("process_vm_readv: pid:%d @0x%" PRI_klx,
	pid, addr);
	return -1;
	}
	}

	return 0;
	}