linux_ptrace.c revision 314210 
1/*-
2 * Copyright (c) 2001 Alexander Kabaev
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer
10 *    in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote products
15 *    derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD: stable/11/sys/i386/linux/linux_ptrace.c 314210 2017-02-24 16:02:01Z kib $");
31
32#include "opt_cpu.h"
33
34#include <sys/param.h>
35#include <sys/lock.h>
36#include <sys/mutex.h>
37#include <sys/proc.h>
38#include <sys/ptrace.h>
39#include <sys/syscallsubr.h>
40#include <sys/systm.h>
41
42#include <machine/md_var.h>
43#include <machine/pcb.h>
44#include <machine/reg.h>
45
46#include <i386/linux/linux.h>
47#include <i386/linux/linux_proto.h>
48#include <compat/linux/linux_signal.h>
49
50/*
51 *   Linux ptrace requests numbers. Mostly identical to FreeBSD,
52 *   except for MD ones and PT_ATTACH/PT_DETACH.
53 */
54#define	PTRACE_TRACEME		0
55#define	PTRACE_PEEKTEXT		1
56#define	PTRACE_PEEKDATA		2
57#define	PTRACE_PEEKUSR		3
58#define	PTRACE_POKETEXT		4
59#define	PTRACE_POKEDATA		5
60#define	PTRACE_POKEUSR		6
61#define	PTRACE_CONT		7
62#define	PTRACE_KILL		8
63#define	PTRACE_SINGLESTEP	9
64
65#define PTRACE_ATTACH		16
66#define PTRACE_DETACH		17
67
68#define	LINUX_PTRACE_SYSCALL	24
69
70#define PTRACE_GETREGS		12
71#define PTRACE_SETREGS		13
72#define PTRACE_GETFPREGS	14
73#define PTRACE_SETFPREGS	15
74#define PTRACE_GETFPXREGS	18
75#define PTRACE_SETFPXREGS	19
76
77#define PTRACE_SETOPTIONS	21
78
79/*
80 * Linux keeps debug registers at the following
81 * offset in the user struct
82 */
83#define LINUX_DBREG_OFFSET	252
84#define LINUX_DBREG_SIZE	(8*sizeof(l_int))
85
86static __inline int
87map_signum(int signum)
88{
89
90	signum = linux_to_bsd_signal(signum);
91	return ((signum == SIGSTOP)? 0 : signum);
92}
93
94struct linux_pt_reg {
95	l_long	ebx;
96	l_long	ecx;
97	l_long	edx;
98	l_long	esi;
99	l_long	edi;
100	l_long	ebp;
101	l_long	eax;
102	l_int	xds;
103	l_int	xes;
104	l_int	xfs;
105	l_int	xgs;
106	l_long	orig_eax;
107	l_long	eip;
108	l_int	xcs;
109	l_long	eflags;
110	l_long	esp;
111	l_int	xss;
112};
113
114/*
115 *   Translate i386 ptrace registers between Linux and FreeBSD formats.
116 *   The translation is pretty straighforward, for all registers, but
117 *   orig_eax on Linux side and r_trapno and r_err in FreeBSD
118 */
119static void
120map_regs_to_linux(struct reg *bsd_r, struct linux_pt_reg *linux_r)
121{
122	linux_r->ebx = bsd_r->r_ebx;
123	linux_r->ecx = bsd_r->r_ecx;
124	linux_r->edx = bsd_r->r_edx;
125	linux_r->esi = bsd_r->r_esi;
126	linux_r->edi = bsd_r->r_edi;
127	linux_r->ebp = bsd_r->r_ebp;
128	linux_r->eax = bsd_r->r_eax;
129	linux_r->xds = bsd_r->r_ds;
130	linux_r->xes = bsd_r->r_es;
131	linux_r->xfs = bsd_r->r_fs;
132	linux_r->xgs = bsd_r->r_gs;
133	linux_r->orig_eax = bsd_r->r_eax;
134	linux_r->eip = bsd_r->r_eip;
135	linux_r->xcs = bsd_r->r_cs;
136	linux_r->eflags = bsd_r->r_eflags;
137	linux_r->esp = bsd_r->r_esp;
138	linux_r->xss = bsd_r->r_ss;
139}
140
141static void
142map_regs_from_linux(struct reg *bsd_r, struct linux_pt_reg *linux_r)
143{
144	bsd_r->r_ebx = linux_r->ebx;
145	bsd_r->r_ecx = linux_r->ecx;
146	bsd_r->r_edx = linux_r->edx;
147	bsd_r->r_esi = linux_r->esi;
148	bsd_r->r_edi = linux_r->edi;
149	bsd_r->r_ebp = linux_r->ebp;
150	bsd_r->r_eax = linux_r->eax;
151	bsd_r->r_ds  = linux_r->xds;
152	bsd_r->r_es  = linux_r->xes;
153	bsd_r->r_fs  = linux_r->xfs;
154	bsd_r->r_gs  = linux_r->xgs;
155	bsd_r->r_eip = linux_r->eip;
156	bsd_r->r_cs  = linux_r->xcs;
157	bsd_r->r_eflags = linux_r->eflags;
158	bsd_r->r_esp = linux_r->esp;
159	bsd_r->r_ss = linux_r->xss;
160}
161
162struct linux_pt_fpreg {
163	l_long cwd;
164	l_long swd;
165	l_long twd;
166	l_long fip;
167	l_long fcs;
168	l_long foo;
169	l_long fos;
170	l_long st_space[2*10];
171};
172
173static void
174map_fpregs_to_linux(struct fpreg *bsd_r, struct linux_pt_fpreg *linux_r)
175{
176	linux_r->cwd = bsd_r->fpr_env[0];
177	linux_r->swd = bsd_r->fpr_env[1];
178	linux_r->twd = bsd_r->fpr_env[2];
179	linux_r->fip = bsd_r->fpr_env[3];
180	linux_r->fcs = bsd_r->fpr_env[4];
181	linux_r->foo = bsd_r->fpr_env[5];
182	linux_r->fos = bsd_r->fpr_env[6];
183	bcopy(bsd_r->fpr_acc, linux_r->st_space, sizeof(linux_r->st_space));
184}
185
186static void
187map_fpregs_from_linux(struct fpreg *bsd_r, struct linux_pt_fpreg *linux_r)
188{
189	bsd_r->fpr_env[0] = linux_r->cwd;
190	bsd_r->fpr_env[1] = linux_r->swd;
191	bsd_r->fpr_env[2] = linux_r->twd;
192	bsd_r->fpr_env[3] = linux_r->fip;
193	bsd_r->fpr_env[4] = linux_r->fcs;
194	bsd_r->fpr_env[5] = linux_r->foo;
195	bsd_r->fpr_env[6] = linux_r->fos;
196	bcopy(bsd_r->fpr_acc, linux_r->st_space, sizeof(bsd_r->fpr_acc));
197}
198
199struct linux_pt_fpxreg {
200	l_ushort	cwd;
201	l_ushort	swd;
202	l_ushort	twd;
203	l_ushort	fop;
204	l_long		fip;
205	l_long		fcs;
206	l_long		foo;
207	l_long		fos;
208	l_long		mxcsr;
209	l_long		reserved;
210	l_long		st_space[32];
211	l_long		xmm_space[32];
212	l_long		padding[56];
213};
214
215static int
216linux_proc_read_fpxregs(struct thread *td, struct linux_pt_fpxreg *fpxregs)
217{
218
219	PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
220	if (cpu_fxsr == 0 || (td->td_proc->p_flag & P_INMEM) == 0)
221		return (EIO);
222	bcopy(&get_pcb_user_save_td(td)->sv_xmm, fpxregs, sizeof(*fpxregs));
223	return (0);
224}
225
226static int
227linux_proc_write_fpxregs(struct thread *td, struct linux_pt_fpxreg *fpxregs)
228{
229
230	PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
231	if (cpu_fxsr == 0 || (td->td_proc->p_flag & P_INMEM) == 0)
232		return (EIO);
233	bcopy(fpxregs, &get_pcb_user_save_td(td)->sv_xmm, sizeof(*fpxregs));
234	return (0);
235}
236
237int
238linux_ptrace(struct thread *td, struct linux_ptrace_args *uap)
239{
240	union {
241		struct linux_pt_reg	reg;
242		struct linux_pt_fpreg	fpreg;
243		struct linux_pt_fpxreg	fpxreg;
244	} r;
245	union {
246		struct reg		bsd_reg;
247		struct fpreg		bsd_fpreg;
248		struct dbreg		bsd_dbreg;
249	} u;
250	void *addr;
251	pid_t pid;
252	int error, req;
253
254	error = 0;
255
256	/* by default, just copy data intact */
257	req  = uap->req;
258	pid  = (pid_t)uap->pid;
259	addr = (void *)uap->addr;
260
261	switch (req) {
262	case PTRACE_TRACEME:
263	case PTRACE_POKETEXT:
264	case PTRACE_POKEDATA:
265	case PTRACE_KILL:
266		error = kern_ptrace(td, req, pid, addr, uap->data);
267		break;
268	case PTRACE_PEEKTEXT:
269	case PTRACE_PEEKDATA: {
270		/* need to preserve return value */
271		int rval = td->td_retval[0];
272		error = kern_ptrace(td, req, pid, addr, 0);
273		if (error == 0)
274			error = copyout(td->td_retval, (void *)uap->data,
275			    sizeof(l_int));
276		td->td_retval[0] = rval;
277		break;
278	}
279	case PTRACE_DETACH:
280		error = kern_ptrace(td, PT_DETACH, pid, (void *)1,
281		     map_signum(uap->data));
282		break;
283	case PTRACE_SINGLESTEP:
284	case PTRACE_CONT:
285		error = kern_ptrace(td, req, pid, (void *)1,
286		     map_signum(uap->data));
287		break;
288	case PTRACE_ATTACH:
289		error = kern_ptrace(td, PT_ATTACH, pid, addr, uap->data);
290		break;
291	case PTRACE_GETREGS:
292		/* Linux is using data where FreeBSD is using addr */
293		error = kern_ptrace(td, PT_GETREGS, pid, &u.bsd_reg, 0);
294		if (error == 0) {
295			map_regs_to_linux(&u.bsd_reg, &r.reg);
296			error = copyout(&r.reg, (void *)uap->data,
297			    sizeof(r.reg));
298		}
299		break;
300	case PTRACE_SETREGS:
301		/* Linux is using data where FreeBSD is using addr */
302		error = copyin((void *)uap->data, &r.reg, sizeof(r.reg));
303		if (error == 0) {
304			map_regs_from_linux(&u.bsd_reg, &r.reg);
305			error = kern_ptrace(td, PT_SETREGS, pid, &u.bsd_reg, 0);
306		}
307		break;
308	case PTRACE_GETFPREGS:
309		/* Linux is using data where FreeBSD is using addr */
310		error = kern_ptrace(td, PT_GETFPREGS, pid, &u.bsd_fpreg, 0);
311		if (error == 0) {
312			map_fpregs_to_linux(&u.bsd_fpreg, &r.fpreg);
313			error = copyout(&r.fpreg, (void *)uap->data,
314			    sizeof(r.fpreg));
315		}
316		break;
317	case PTRACE_SETFPREGS:
318		/* Linux is using data where FreeBSD is using addr */
319		error = copyin((void *)uap->data, &r.fpreg, sizeof(r.fpreg));
320		if (error == 0) {
321			map_fpregs_from_linux(&u.bsd_fpreg, &r.fpreg);
322			error = kern_ptrace(td, PT_SETFPREGS, pid,
323			    &u.bsd_fpreg, 0);
324		}
325		break;
326	case PTRACE_SETFPXREGS:
327		error = copyin((void *)uap->data, &r.fpxreg, sizeof(r.fpxreg));
328		if (error)
329			break;
330		/* FALL THROUGH */
331	case PTRACE_GETFPXREGS: {
332		struct proc *p;
333		struct thread *td2;
334
335		if (sizeof(struct linux_pt_fpxreg) != sizeof(struct savexmm)) {
336			static int once = 0;
337			if (!once) {
338				printf("linux: savexmm != linux_pt_fpxreg\n");
339				once = 1;
340			}
341			error = EIO;
342			break;
343		}
344
345		if ((p = pfind(uap->pid)) == NULL) {
346			error = ESRCH;
347			break;
348		}
349
350		/* Exiting processes can't be debugged. */
351		if ((p->p_flag & P_WEXIT) != 0) {
352			error = ESRCH;
353			goto fail;
354		}
355
356		if ((error = p_candebug(td, p)) != 0)
357			goto fail;
358
359		/* System processes can't be debugged. */
360		if ((p->p_flag & P_SYSTEM) != 0) {
361			error = EINVAL;
362			goto fail;
363		}
364
365		/* not being traced... */
366		if ((p->p_flag & P_TRACED) == 0) {
367			error = EPERM;
368			goto fail;
369		}
370
371		/* not being traced by YOU */
372		if (p->p_pptr != td->td_proc) {
373			error = EBUSY;
374			goto fail;
375		}
376
377		/* not currently stopped */
378		if (!P_SHOULDSTOP(p) || (p->p_flag & P_WAITED) == 0) {
379			error = EBUSY;
380			goto fail;
381		}
382
383		if (req == PTRACE_GETFPXREGS) {
384			_PHOLD(p);	/* may block */
385			td2 = FIRST_THREAD_IN_PROC(p);
386			error = linux_proc_read_fpxregs(td2, &r.fpxreg);
387			_PRELE(p);
388			PROC_UNLOCK(p);
389			if (error == 0)
390				error = copyout(&r.fpxreg, (void *)uap->data,
391				    sizeof(r.fpxreg));
392		} else {
393			/* clear dangerous bits exactly as Linux does*/
394			r.fpxreg.mxcsr &= 0xffbf;
395			_PHOLD(p);	/* may block */
396			td2 = FIRST_THREAD_IN_PROC(p);
397			error = linux_proc_write_fpxregs(td2, &r.fpxreg);
398			_PRELE(p);
399			PROC_UNLOCK(p);
400		}
401		break;
402
403	fail:
404		PROC_UNLOCK(p);
405		break;
406	}
407	case PTRACE_PEEKUSR:
408	case PTRACE_POKEUSR: {
409		error = EIO;
410
411		/* check addr for alignment */
412		if (uap->addr < 0 || uap->addr & (sizeof(l_int) - 1))
413			break;
414		/*
415		 * Allow linux programs to access register values in
416		 * user struct. We simulate this through PT_GET/SETREGS
417		 * as necessary.
418		 */
419		if (uap->addr < sizeof(struct linux_pt_reg)) {
420			error = kern_ptrace(td, PT_GETREGS, pid, &u.bsd_reg, 0);
421			if (error != 0)
422				break;
423
424			map_regs_to_linux(&u.bsd_reg, &r.reg);
425			if (req == PTRACE_PEEKUSR) {
426				error = copyout((char *)&r.reg + uap->addr,
427				    (void *)uap->data, sizeof(l_int));
428				break;
429			}
430
431			*(l_int *)((char *)&r.reg + uap->addr) =
432			    (l_int)uap->data;
433
434			map_regs_from_linux(&u.bsd_reg, &r.reg);
435			error = kern_ptrace(td, PT_SETREGS, pid, &u.bsd_reg, 0);
436		}
437
438		/*
439		 * Simulate debug registers access
440		 */
441		if (uap->addr >= LINUX_DBREG_OFFSET &&
442		    uap->addr <= LINUX_DBREG_OFFSET + LINUX_DBREG_SIZE) {
443			error = kern_ptrace(td, PT_GETDBREGS, pid, &u.bsd_dbreg,
444			    0);
445			if (error != 0)
446				break;
447
448			uap->addr -= LINUX_DBREG_OFFSET;
449			if (req == PTRACE_PEEKUSR) {
450				error = copyout((char *)&u.bsd_dbreg +
451				    uap->addr, (void *)uap->data,
452				    sizeof(l_int));
453				break;
454			}
455
456			*(l_int *)((char *)&u.bsd_dbreg + uap->addr) =
457			     uap->data;
458			error = kern_ptrace(td, PT_SETDBREGS, pid,
459			    &u.bsd_dbreg, 0);
460		}
461
462		break;
463	}
464	case LINUX_PTRACE_SYSCALL:
465		/* fall through */
466	default:
467		printf("linux: ptrace(%u, ...) not implemented\n",
468		    (unsigned int)uap->req);
469		error = EINVAL;
470		break;
471	}
472
473	return (error);
474}
475