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      1 /*	$NetBSD: linux_ptrace.c,v 1.23 2021/09/07 11:43:04 riastradh 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 
     33 #include <sys/cdefs.h>
     34 __KERNEL_RCSID(0, "$NetBSD: linux_ptrace.c,v 1.23 2021/09/07 11:43:04 riastradh Exp $");
     35 
     36 #include <sys/param.h>
     37 #include <sys/mount.h>
     38 #include <sys/proc.h>
     39 #include <sys/ptrace.h>
     40 #include <sys/systm.h>
     41 #include <sys/syscallargs.h>
     42 #include <uvm/uvm_extern.h>
     43 
     44 #include <machine/reg.h>
     45 #include <machine/pcb.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 /*
     61  * On ARMv2, uregs contains R0--R15, orig_R0.
     62  * On ARMv3 and later, it's R0--R15, CPSR, orig_R0.
     63  * As far as I can see, Linux doesn't initialise orig_R0 on ARMv2, so we
     64  * just produce the ARMv3 version.
     65  */
     66 
     67 struct linux_reg {
     68 	long uregs[18];
     69 };
     70 
     71 #define LINUX_REG_R0	0
     72 #define LINUX_REG_R1	1
     73 #define LINUX_REG_R2	2
     74 #define LINUX_REG_R3	3
     75 #define LINUX_REG_R4	4
     76 #define LINUX_REG_R5	5
     77 #define LINUX_REG_R6	6
     78 #define LINUX_REG_R7	7
     79 #define LINUX_REG_R8	8
     80 #define LINUX_REG_R9	9
     81 #define LINUX_REG_R10	10
     82 #define LINUX_REG_FP	11
     83 #define LINUX_REG_IP	12
     84 #define LINUX_REG_SP	13
     85 #define LINUX_REG_LR	14
     86 #define LINUX_REG_PC	15
     87 #define LINUX_REG_CPSR	16
     88 #define LINUX_REG_ORIG_R0 17
     89 
     90 int linux_ptrace_disabled = 1;	/* bitrotted */
     91 
     92 int
     93 linux_sys_ptrace_arch(struct lwp *l, const struct linux_sys_ptrace_args *uap,
     94     register_t *retval)
     95 {
     96 	/* {
     97 		syscallarg(int) request;
     98 		syscallarg(int) pid;
     99 		syscallarg(int) addr;
    100 		syscallarg(int) data;
    101 	} */
    102 	struct proc *p = l->l_proc, *t;
    103 	struct lwp *lt;
    104 #ifdef _ARM_ARCH_6
    105 	struct pcb *pcb;
    106 	void *val;
    107 #endif
    108 	struct reg *regs = NULL;
    109 	struct linux_reg *linux_regs = NULL;
    110 	int request, error;
    111 
    112 	if (linux_ptrace_disabled)
    113 		return ENOSYS;
    114 
    115 	error = 0;
    116 	request = SCARG(uap, request);
    117 	regs = kmem_alloc(sizeof(struct reg), KM_SLEEP);
    118 	linux_regs = kmem_alloc(sizeof(struct linux_reg), KM_SLEEP);
    119 
    120 	switch (request) {
    121 	case LINUX_PTRACE_GETREGS:
    122 		break;
    123 	case LINUX_PTRACE_SETREGS:
    124 		error = copyin((void *)SCARG(uap, data), linux_regs,
    125 		    sizeof(struct linux_reg));
    126 		if (error) {
    127 			goto out;
    128 		}
    129 		break;
    130 	default:
    131 		error = EIO;
    132 		goto out;
    133 	}
    134 
    135 	/* Find the process we are supposed to be operating on. */
    136 	mutex_enter(&proc_lock);
    137 	if ((t = proc_find(SCARG(uap, pid))) == NULL) {
    138 		mutex_exit(&proc_lock);
    139 		error = ESRCH;
    140 		goto out;
    141 	}
    142 	mutex_enter(t->p_lock);
    143 
    144 	/*
    145 	 * You cannot do what you want to the process if:
    146 	 * 1. It is not being traced at all,
    147 	 */
    148 	if (!ISSET(t->p_slflag, PSL_TRACED)) {
    149 		mutex_exit(t->p_lock);
    150 		mutex_exit(&proc_lock);
    151 		error = EPERM;
    152 		goto out;
    153 	}
    154 	/*
    155 	 * 2. It is being traced by procfs (which has different signal
    156 	 *    delivery semantics),
    157 	 * 3. It is not being traced by _you_, or
    158 	 * 4. It is not currently stopped.
    159 	 */
    160 	if (t->p_pptr != p || t->p_stat != SSTOP || !t->p_waited) {
    161 		mutex_exit(t->p_lock);
    162 		mutex_exit(&proc_lock);
    163 		error = EBUSY;
    164 		goto out;
    165 	}
    166 	mutex_exit(&proc_lock);
    167 	/* XXX: ptrace needs revamp for multi-threading support. */
    168 	if (t->p_nlwps > 1) {
    169 		mutex_exit(t->p_lock);
    170 		error = ENOSYS;
    171 		goto out;
    172 	}
    173 	lt = LIST_FIRST(&t->p_lwps);
    174 	*retval = 0;
    175 
    176 	switch (request) {
    177 	case LINUX_PTRACE_GETREGS:
    178 		error = process_read_regs(lt, regs);
    179 		mutex_exit(t->p_lock);
    180 		if (error) {
    181 			break;
    182 		}
    183 		memset(linux_regs, 0, sizeof(*linux_regs));
    184 		memcpy(linux_regs->uregs, regs->r, 13 * sizeof(register_t));
    185 		linux_regs->uregs[LINUX_REG_SP] = regs->r_sp;
    186 		linux_regs->uregs[LINUX_REG_LR] = regs->r_lr;
    187 		linux_regs->uregs[LINUX_REG_PC] = regs->r_pc;
    188 		linux_regs->uregs[LINUX_REG_CPSR] = regs->r_cpsr;
    189 		linux_regs->uregs[LINUX_REG_ORIG_R0] = regs->r[0];
    190 
    191 		error = copyout(linux_regs, (void *)SCARG(uap, data),
    192 		    sizeof(struct linux_reg));
    193 		break;
    194 
    195 	case LINUX_PTRACE_SETREGS:
    196 		memcpy(regs->r, linux_regs->uregs, 13 * sizeof(register_t));
    197 		regs->r_sp = linux_regs->uregs[LINUX_REG_SP];
    198 		regs->r_lr = linux_regs->uregs[LINUX_REG_LR];
    199 		regs->r_pc = linux_regs->uregs[LINUX_REG_PC];
    200 		regs->r_cpsr = linux_regs->uregs[LINUX_REG_CPSR];
    201 		error = process_write_regs(lt, regs);
    202 		mutex_exit(t->p_lock);
    203 		break;
    204 
    205 #ifdef _ARM_ARCH_6
    206 #define LINUX_PTRACE_GET_THREAD_AREA	22
    207 	case LINUX_PTRACE_GET_THREAD_AREA:
    208 		mutex_exit(t->p_lock);
    209 		pcb = lwp_getpcb(l);
    210 		val = (void *)pcb->pcb_user_pid_ro;
    211 		error = copyout(&val, (void *)SCARG(uap, data), sizeof(val));
    212 		break;
    213 #endif
    214 
    215 	default:
    216 		mutex_exit(t->p_lock);
    217 	}
    218 out:
    219 	if (regs)
    220 		kmem_free(regs, sizeof(*regs));
    221 	if (linux_regs)
    222 		kmem_free(linux_regs, sizeof(*linux_regs));
    223 	return error;
    224 
    225 }
    226