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linux_ptrace.c revision 1.28
      1 /*	$NetBSD: linux_ptrace.c,v 1.27 2014/01/04 00:10:03 dsl Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1999 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Matthias Scheler.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __KERNEL_RCSID(0, "$NetBSD: linux_ptrace.c,v 1.27 2014/01/04 00:10:03 dsl Exp $");
     34 
     35 #include <sys/param.h>
     36 #include <sys/malloc.h>
     37 #include <sys/mount.h>
     38 #include <sys/proc.h>
     39 #include <sys/ptrace.h>
     40 #include <sys/systm.h>
     41 #include <sys/syscall.h>
     42 #include <sys/syscallargs.h>
     43 #include <uvm/uvm_extern.h>
     44 
     45 #include <machine/reg.h>
     46 
     47 #include <compat/linux/common/linux_types.h>
     48 #include <compat/linux/common/linux_ptrace.h>
     49 #include <compat/linux/common/linux_signal.h>
     50 
     51 #include <compat/linux/common/linux_util.h>
     52 #include <compat/linux/common/linux_machdep.h>
     53 #include <compat/linux/common/linux_emuldata.h>
     54 #include <compat/linux/common/linux_exec.h>	/* for emul_linux */
     55 
     56 #include <compat/linux/linux_syscallargs.h>
     57 
     58 #include <lib/libkern/libkern.h>	/* for offsetof() */
     59 
     60 struct linux_reg {
     61 	long ebx;
     62 	long ecx;
     63 	long edx;
     64 	long esi;
     65 	long edi;
     66 	long ebp;
     67 	long eax;
     68 	long xds, xes;		/* unsigned short ds, __ds, es, __es; */
     69 	long __fs, __gs;	/* unsigned short fs, __fs, gs, __gs; */
     70 	long orig_eax;
     71 	long eip;
     72 	long xcs;		/* unsigned short cs, __cs; */
     73 	long eflags;
     74 	long esp;
     75 	long xss;		/* unsigned short ss, __ss; */
     76 };
     77 
     78 /* structure used for storing floating point context */
     79 struct linux_fpctx {
     80 	long cwd;
     81 	long swd;
     82 	long twd;
     83 	long fip;
     84 	long fcs;
     85 	long foo;
     86 	long fos;
     87 	long st_space[20];
     88 };
     89 
     90 /* user struct for linux process - this is used for Linux ptrace emulation */
     91 /* most of it is junk only used by gdb */
     92 struct linux_user {
     93 	struct linux_reg regs;		/* registers */
     94 	int u_fpvalid;		/* true if math co-processor being used. */
     95 	struct linux_fpctx i387;	/* Math Co-processor registers. */
     96 /* The rest of this junk is to help gdb figure out what goes where */
     97 #define lusr_startgdb	u_tsize
     98 	unsigned long int u_tsize;	/* Text segment size (pages). */
     99 	unsigned long int u_dsize;	/* Data segment size (pages). */
    100 	unsigned long int u_ssize;	/* Stack segment size (pages). */
    101 	unsigned long start_code;	/* Starting virtual address of text. */
    102 	unsigned long start_stack;	/* Starting virtual address of stack
    103 					   area. This is actually the bottom of
    104 					   the stack, the top of the stack is
    105 					   always found in the esp register. */
    106 	long int __signal;  		/* Signal that caused the core dump. */
    107 	int __reserved;			/* unused */
    108 	void *u_ar0;			/* Used by gdb to help find the values
    109 					   for the registers. */
    110 	struct linux_fpctx *u_fpstate;	/* Math Co-processor pointer. */
    111 	unsigned long __magic;		/* To uniquely identify a core file */
    112 	char u_comm[32];		/* User command that was responsible */
    113 	int u_debugreg[8];
    114 #define u_debugreg_end	u_debugreg[7]
    115 };
    116 
    117 #define LUSR_OFF(member)	offsetof(struct linux_user, member)
    118 #define ISSET(t, f)		((t) & (f))
    119 
    120 int linux_ptrace_disabled = 1;	/* bitrotted */
    121 
    122 int
    123 linux_sys_ptrace_arch(struct lwp *l, const struct linux_sys_ptrace_args *uap,
    124     register_t *retval)
    125 {
    126 	/* {
    127 		syscallarg(int) request;
    128 		syscallarg(int) pid;
    129 		syscallarg(int) addr;
    130 		syscallarg(int) data;
    131 	} */
    132 	struct proc *p = l->l_proc, *t;
    133 	struct lwp *lt;
    134 	struct reg *regs = NULL;
    135 	struct fpreg *fpregs = NULL;
    136 	struct linux_reg *linux_regs = NULL;
    137 	struct linux_fpctx *linux_fpregs = NULL;
    138 	struct linux_emuldata *led;
    139 	int request, error, addr;
    140 	size_t fp_size;
    141 
    142 	if (linux_ptrace_disabled)
    143 		return ENOSYS;
    144 
    145 	error = 0;
    146 	request = SCARG(uap, request);
    147 
    148 	switch (request) {
    149 	case LINUX_PTRACE_PEEKUSR:
    150 	case LINUX_PTRACE_POKEUSR:
    151 		break;
    152 	case LINUX_PTRACE_GETREGS:
    153 	case LINUX_PTRACE_SETREGS:
    154 		regs = kmem_alloc(sizeof(struct reg), KM_SLEEP);
    155 		linux_regs = kmem_alloc(sizeof(struct linux_reg), KM_SLEEP);
    156 		if (request == LINUX_PTRACE_SETREGS) {
    157 			error = copyin((void *)SCARG(uap, data), linux_regs,
    158 			    sizeof(struct linux_reg));
    159 			if (error) {
    160 				goto out;
    161 			}
    162 		}
    163 		break;
    164 	case LINUX_PTRACE_GETFPREGS:
    165 	case LINUX_PTRACE_SETFPREGS:
    166 		fpregs = kmem_alloc(sizeof(struct fpreg), KM_SLEEP);
    167 		linux_fpregs = kmem_alloc(sizeof(struct linux_fpctx), KM_SLEEP);
    168 		if (request == LINUX_PTRACE_SETFPREGS) {
    169 			error = copyin((void *)SCARG(uap, data), linux_fpregs,
    170 			    sizeof(struct linux_fpctx));
    171 			if (error) {
    172 				goto out;
    173 			}
    174 		}
    175 		break;
    176 	default:
    177 		error = EIO;
    178 		goto out;
    179 	}
    180 
    181 	/* Find the process we are supposed to be operating on. */
    182 	mutex_enter(proc_lock);
    183 	if ((t = proc_find(SCARG(uap, pid))) == NULL) {
    184 		mutex_exit(proc_lock);
    185 		return ESRCH;
    186 	}
    187 	mutex_enter(t->p_lock);
    188 	mutex_exit(proc_lock);
    189 
    190 	/*
    191 	 * You cannot do what you want to the process if:
    192 	 * 1. It is not being traced at all,
    193 	 */
    194 	if (!ISSET(t->p_slflag, PSL_TRACED)) {
    195 		mutex_exit(t->p_lock);
    196 		error = EPERM;
    197 		goto out;
    198 	}
    199 	/*
    200 	 * 2. It is being traced by procfs (which has different signal
    201 	 *    delivery semantics),
    202 	 * 3. It is not being traced by _you_, or
    203 	 * 4. It is not currently stopped.
    204 	 */
    205 	if (ISSET(t->p_slflag, PSL_FSTRACE) || t->p_pptr != p ||
    206 	    t->p_stat != SSTOP || !t->p_waited) {
    207 		mutex_exit(t->p_lock);
    208 		error = EBUSY;
    209 		goto out;
    210 	}
    211 	/* XXX: ptrace needs revamp for multi-threading support. */
    212 	if (t->p_nlwps > 1) {
    213 		mutex_exit(t->p_lock);
    214 		error = ENOSYS;
    215 		goto out;
    216 	}
    217 	lt = LIST_FIRST(&t->p_lwps);
    218 	*retval = 0;
    219 
    220 	switch (request) {
    221 	case LINUX_PTRACE_GETREGS:
    222 		error = process_read_regs(lt, regs);
    223 		mutex_exit(t->p_lock);
    224 		if (error) {
    225 			break;
    226 		}
    227 		linux_regs->ebx = regs->r_ebx;
    228 		linux_regs->ecx = regs->r_ecx;
    229 		linux_regs->edx = regs->r_edx;
    230 		linux_regs->esi = regs->r_esi;
    231 		linux_regs->edi = regs->r_edi;
    232 		linux_regs->ebp = regs->r_ebp;
    233 		linux_regs->eax = regs->r_eax;
    234 		linux_regs->xds = regs->r_ds;
    235 		linux_regs->xes = regs->r_es;
    236 		linux_regs->orig_eax = regs->r_eax; /* XXX is this correct? */
    237 		linux_regs->eip = regs->r_cs + regs->r_eip;
    238 		linux_regs->xcs = regs->r_cs;
    239 		linux_regs->eflags = regs->r_eflags;
    240 		linux_regs->esp = regs->r_esp;
    241 		linux_regs->xss = regs->r_ss;
    242 
    243 		error = copyout(linux_regs, (void *)SCARG(uap, data),
    244 		    sizeof(struct linux_reg));
    245 		break;
    246 
    247 	case LINUX_PTRACE_SETREGS:
    248 		regs->r_ebx = linux_regs->ebx;
    249 		regs->r_ecx = linux_regs->ecx;
    250 		regs->r_edx = linux_regs->edx;
    251 		regs->r_esi = linux_regs->esi;
    252 		regs->r_edi = linux_regs->edi;
    253 		regs->r_ebp = linux_regs->ebp;
    254 		regs->r_eax = linux_regs->eax;
    255 		regs->r_ds = linux_regs->xds;
    256 		regs->r_es = linux_regs->xes;
    257 		regs->r_eip = linux_regs->eip - linux_regs->xcs;
    258 		regs->r_cs = linux_regs->xcs;
    259 		regs->r_eflags = linux_regs->eflags;
    260 		regs->r_esp = linux_regs->esp;
    261 		regs->r_ss = linux_regs->xss;
    262 
    263 		error = process_write_regs(lt, regs);
    264 		mutex_exit(t->p_lock);
    265 		break;
    266 
    267 	case LINUX_PTRACE_GETFPREGS:
    268 		fp_size = sizeof fpregs;
    269 		error = process_read_fpregs(lt, fpregs, &fp_size);
    270 		mutex_exit(t->p_lock);
    271 		if (error) {
    272 			break;
    273 		}
    274 		/* Zero the contents if NetBSD fpreg structure is smaller */
    275 		if (fp_size < sizeof(struct linux_fpctx)) {
    276 			memset(linux_fpregs, '\0', sizeof(struct linux_fpctx));
    277 		}
    278 		memcpy(linux_fpregs, fpregs,
    279 		    min(sizeof(struct linux_fpctx), fp_size));
    280 		error = copyout(linux_fpregs, (void *)SCARG(uap, data),
    281 		    sizeof(struct linux_fpctx));
    282 		break;
    283 
    284 	case LINUX_PTRACE_SETFPREGS:
    285 		memset(fpregs, '\0', sizeof(struct fpreg));
    286 		memcpy(fpregs, linux_fpregs,
    287 		    min(sizeof(struct linux_fpctx), sizeof(struct fpreg)));
    288 		error = process_write_regs(lt, regs);
    289 		mutex_exit(t->p_lock);
    290 		break;
    291 
    292 	case LINUX_PTRACE_PEEKUSR:
    293 		/* XXX locking */
    294 		addr = SCARG(uap, addr);
    295 
    296 		error = 0;
    297 		if (addr < LUSR_OFF(lusr_startgdb)) {
    298 			/* XXX should provide appropriate register */
    299 			error = ENOTSUP;
    300 		} else if (addr == LUSR_OFF(u_tsize))
    301 			*retval = p->p_vmspace->vm_tsize;
    302 		else if (addr == LUSR_OFF(u_dsize))
    303 			*retval = p->p_vmspace->vm_dsize;
    304 		else if (addr == LUSR_OFF(u_ssize))
    305 			*retval = p->p_vmspace->vm_ssize;
    306 		else if (addr == LUSR_OFF(start_code))
    307 			*retval = (register_t) p->p_vmspace->vm_taddr;
    308 		else if (addr == LUSR_OFF(start_stack))
    309 			*retval = (register_t) p->p_vmspace->vm_minsaddr;
    310 		else if (addr == LUSR_OFF(u_ar0))
    311 			*retval = LUSR_OFF(regs);
    312 		else if (addr >= LUSR_OFF(u_debugreg)
    313 			   && addr <= LUSR_OFF(u_debugreg_end)) {
    314 			int off = (addr - LUSR_OFF(u_debugreg)) / sizeof(int);
    315 
    316 			/* only do this for Linux processes */
    317 			if (t->p_emul != &emul_linux) {
    318 				mutex_exit(t->p_lock);
    319 				return EINVAL;
    320 			}
    321 
    322 			led = lt->l_emuldata;
    323 			*retval = led->led_debugreg[off];
    324 		} else if (addr == LUSR_OFF(__signal)) {
    325 			error = ENOTSUP;
    326 		} else if (addr == LUSR_OFF(u_fpstate)) {
    327 			error = ENOTSUP;
    328 		} else if (addr == LUSR_OFF(__magic)) {
    329 			error = ENOTSUP;
    330 		} else if (addr == LUSR_OFF(u_comm)) {
    331 			error = ENOTSUP;
    332 		} else {
    333 #ifdef DEBUG_LINUX
    334 			printf("linux_ptrace: unsupported address: %d\n", addr);
    335 #endif
    336 			error = ENOTSUP;
    337 		}
    338 		mutex_exit(t->p_lock);
    339 		break;
    340 
    341 	case LINUX_PTRACE_POKEUSR:
    342 		/* we only support setting debugregs for now */
    343 		addr = SCARG(uap, addr);
    344 		if (addr >= LUSR_OFF(u_debugreg) &&
    345 		    addr <= LUSR_OFF(u_debugreg_end)) {
    346 			int off = (addr - LUSR_OFF(u_debugreg)) / sizeof(int);
    347 			int data = SCARG(uap, data);
    348 
    349 			/* only do this for Linux processes */
    350 			if (t->p_emul != &emul_linux) {
    351 				mutex_exit(t->p_lock);
    352 				return EINVAL;
    353 			}
    354 			led = lt->l_emuldata;
    355 			led->led_debugreg[off] = data;
    356 		}
    357 		mutex_exit(t->p_lock);
    358 		break;
    359 
    360 	default:
    361 		mutex_exit(t->p_lock);
    362 		break;
    363 	}
    364 out:
    365 	if (regs)
    366 		kmem_free(regs, sizeof(*regs));
    367 	if (linux_regs)
    368 		kmem_free(linux_regs, sizeof(*linux_regs));
    369 	if (fpregs)
    370 		kmem_free(fpregs, sizeof(*fpregs));
    371 	if (linux_fpregs)
    372 		kmem_free(linux_fpregs, sizeof(*linux_fpregs));
    373 
    374 	return error;
    375 }
    376