591 lines
14 KiB
C
591 lines
14 KiB
C
/* ptrace.c */
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/* By Ross Biro 1/23/92 */
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/*
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* Pentium III FXSR, SSE support
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* Gareth Hughes <gareth@valinux.com>, May 2000
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*/
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/smp_lock.h>
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#include <linux/errno.h>
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#include <linux/ptrace.h>
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#include <linux/user.h>
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#include <linux/security.h>
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#include <linux/audit.h>
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#include <asm/uaccess.h>
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#include <asm/pgtable.h>
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#include <asm/system.h>
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#include <asm/processor.h>
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#include <asm/i387.h>
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#include <asm/debugreg.h>
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#include <asm/ldt.h>
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#include <asm/desc.h>
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/*
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* does not yet catch signals sent when the child dies.
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* in exit.c or in signal.c.
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*/
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/* determines which flags the user has access to. */
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/* 1 = access 0 = no access */
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#define FLAG_MASK 0x00044dd5
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/* set's the trap flag. */
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#define TRAP_FLAG 0x100
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/*
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* Offset of eflags on child stack..
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*/
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#define EFL_OFFSET ((EFL-2)*4-sizeof(struct pt_regs))
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/*
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* this routine will get a word off of the processes privileged stack.
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* the offset is how far from the base addr as stored in the TSS.
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* this routine assumes that all the privileged stacks are in our
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* data space.
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*/
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static inline int get_stack_long(struct task_struct *task, int offset)
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{
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unsigned char *stack;
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stack = (unsigned char *)task->thread.esp0;
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stack += offset;
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return (*((int *)stack));
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}
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/*
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* this routine will put a word on the processes privileged stack.
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* the offset is how far from the base addr as stored in the TSS.
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* this routine assumes that all the privileged stacks are in our
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* data space.
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*/
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static inline int put_stack_long(struct task_struct *task, int offset,
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unsigned long data)
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{
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unsigned char * stack;
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stack = (unsigned char *) task->thread.esp0;
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stack += offset;
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*(unsigned long *) stack = data;
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return 0;
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}
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static int putreg(struct task_struct *child,
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unsigned long regno, unsigned long value)
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{
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switch (regno >> 2) {
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case FS:
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if (value && (value & 3) != 3)
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return -EIO;
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child->thread.fs = value;
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return 0;
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case GS:
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if (value && (value & 3) != 3)
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return -EIO;
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child->thread.gs = value;
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return 0;
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case DS:
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case ES:
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if (value && (value & 3) != 3)
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return -EIO;
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value &= 0xffff;
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break;
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case SS:
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case CS:
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if ((value & 3) != 3)
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return -EIO;
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value &= 0xffff;
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break;
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case EFL:
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value &= FLAG_MASK;
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value |= get_stack_long(child, EFL_OFFSET) & ~FLAG_MASK;
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break;
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}
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if (regno > GS*4)
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regno -= 2*4;
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put_stack_long(child, regno - sizeof(struct pt_regs), value);
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return 0;
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}
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static unsigned long getreg(struct task_struct *child,
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unsigned long regno)
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{
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unsigned long retval = ~0UL;
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switch (regno >> 2) {
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case FS:
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retval = child->thread.fs;
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break;
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case GS:
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retval = child->thread.gs;
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break;
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case DS:
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case ES:
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case SS:
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case CS:
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retval = 0xffff;
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/* fall through */
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default:
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if (regno > GS*4)
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regno -= 2*4;
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regno = regno - sizeof(struct pt_regs);
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retval &= get_stack_long(child, regno);
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}
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return retval;
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}
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static void set_singlestep(struct task_struct *child)
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{
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long eflags;
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set_tsk_thread_flag(child, TIF_SINGLESTEP);
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eflags = get_stack_long(child, EFL_OFFSET);
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put_stack_long(child, EFL_OFFSET, eflags | TRAP_FLAG);
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child->ptrace |= PT_DTRACE;
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}
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static void clear_singlestep(struct task_struct *child)
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{
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if (child->ptrace & PT_DTRACE) {
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long eflags;
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clear_tsk_thread_flag(child, TIF_SINGLESTEP);
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eflags = get_stack_long(child, EFL_OFFSET);
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put_stack_long(child, EFL_OFFSET, eflags & ~TRAP_FLAG);
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child->ptrace &= ~PT_DTRACE;
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}
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}
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/*
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* Called by kernel/ptrace.c when detaching..
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*
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* Make sure the single step bit is not set.
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*/
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void ptrace_disable(struct task_struct *child)
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{
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clear_singlestep(child);
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}
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/*
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* Perform get_thread_area on behalf of the traced child.
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*/
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static int
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ptrace_get_thread_area(struct task_struct *child,
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int idx, struct user_desc __user *user_desc)
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{
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struct user_desc info;
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struct desc_struct *desc;
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/*
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* Get the current Thread-Local Storage area:
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*/
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#define GET_BASE(desc) ( \
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(((desc)->a >> 16) & 0x0000ffff) | \
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(((desc)->b << 16) & 0x00ff0000) | \
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( (desc)->b & 0xff000000) )
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#define GET_LIMIT(desc) ( \
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((desc)->a & 0x0ffff) | \
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((desc)->b & 0xf0000) )
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#define GET_32BIT(desc) (((desc)->b >> 22) & 1)
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#define GET_CONTENTS(desc) (((desc)->b >> 10) & 3)
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#define GET_WRITABLE(desc) (((desc)->b >> 9) & 1)
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#define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1)
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#define GET_PRESENT(desc) (((desc)->b >> 15) & 1)
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#define GET_USEABLE(desc) (((desc)->b >> 20) & 1)
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if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
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return -EINVAL;
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desc = child->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
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info.entry_number = idx;
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info.base_addr = GET_BASE(desc);
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info.limit = GET_LIMIT(desc);
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info.seg_32bit = GET_32BIT(desc);
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info.contents = GET_CONTENTS(desc);
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info.read_exec_only = !GET_WRITABLE(desc);
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info.limit_in_pages = GET_LIMIT_PAGES(desc);
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info.seg_not_present = !GET_PRESENT(desc);
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info.useable = GET_USEABLE(desc);
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if (copy_to_user(user_desc, &info, sizeof(info)))
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return -EFAULT;
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return 0;
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}
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/*
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* Perform set_thread_area on behalf of the traced child.
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*/
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static int
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ptrace_set_thread_area(struct task_struct *child,
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int idx, struct user_desc __user *user_desc)
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{
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struct user_desc info;
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struct desc_struct *desc;
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if (copy_from_user(&info, user_desc, sizeof(info)))
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return -EFAULT;
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if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
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return -EINVAL;
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desc = child->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
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if (LDT_empty(&info)) {
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desc->a = 0;
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desc->b = 0;
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} else {
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desc->a = LDT_entry_a(&info);
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desc->b = LDT_entry_b(&info);
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}
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return 0;
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}
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asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
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{
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struct task_struct *child;
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struct user * dummy = NULL;
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int i, ret;
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unsigned long __user *datap = (unsigned long __user *)data;
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lock_kernel();
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ret = -EPERM;
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if (request == PTRACE_TRACEME) {
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/* are we already being traced? */
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if (current->ptrace & PT_PTRACED)
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goto out;
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ret = security_ptrace(current->parent, current);
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if (ret)
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goto out;
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/* set the ptrace bit in the process flags. */
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current->ptrace |= PT_PTRACED;
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ret = 0;
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goto out;
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}
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ret = -ESRCH;
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read_lock(&tasklist_lock);
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child = find_task_by_pid(pid);
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if (child)
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get_task_struct(child);
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read_unlock(&tasklist_lock);
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if (!child)
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goto out;
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ret = -EPERM;
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if (pid == 1) /* you may not mess with init */
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goto out_tsk;
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if (request == PTRACE_ATTACH) {
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ret = ptrace_attach(child);
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goto out_tsk;
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}
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ret = ptrace_check_attach(child, request == PTRACE_KILL);
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if (ret < 0)
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goto out_tsk;
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switch (request) {
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/* when I and D space are separate, these will need to be fixed. */
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case PTRACE_PEEKTEXT: /* read word at location addr. */
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case PTRACE_PEEKDATA: {
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unsigned long tmp;
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int copied;
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copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
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ret = -EIO;
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if (copied != sizeof(tmp))
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break;
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ret = put_user(tmp, datap);
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break;
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}
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/* read the word at location addr in the USER area. */
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case PTRACE_PEEKUSR: {
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unsigned long tmp;
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ret = -EIO;
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if ((addr & 3) || addr < 0 ||
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addr > sizeof(struct user) - 3)
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break;
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tmp = 0; /* Default return condition */
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if(addr < FRAME_SIZE*sizeof(long))
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tmp = getreg(child, addr);
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if(addr >= (long) &dummy->u_debugreg[0] &&
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addr <= (long) &dummy->u_debugreg[7]){
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addr -= (long) &dummy->u_debugreg[0];
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addr = addr >> 2;
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tmp = child->thread.debugreg[addr];
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}
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ret = put_user(tmp, datap);
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break;
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}
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/* when I and D space are separate, this will have to be fixed. */
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case PTRACE_POKETEXT: /* write the word at location addr. */
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case PTRACE_POKEDATA:
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ret = 0;
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if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
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break;
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ret = -EIO;
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break;
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case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
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ret = -EIO;
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if ((addr & 3) || addr < 0 ||
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addr > sizeof(struct user) - 3)
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break;
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if (addr < FRAME_SIZE*sizeof(long)) {
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ret = putreg(child, addr, data);
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break;
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}
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/* We need to be very careful here. We implicitly
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want to modify a portion of the task_struct, and we
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have to be selective about what portions we allow someone
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to modify. */
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ret = -EIO;
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if(addr >= (long) &dummy->u_debugreg[0] &&
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addr <= (long) &dummy->u_debugreg[7]){
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if(addr == (long) &dummy->u_debugreg[4]) break;
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if(addr == (long) &dummy->u_debugreg[5]) break;
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if(addr < (long) &dummy->u_debugreg[4] &&
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((unsigned long) data) >= TASK_SIZE-3) break;
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/* Sanity-check data. Take one half-byte at once with
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* check = (val >> (16 + 4*i)) & 0xf. It contains the
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* R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits
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* 2 and 3 are LENi. Given a list of invalid values,
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* we do mask |= 1 << invalid_value, so that
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* (mask >> check) & 1 is a correct test for invalid
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* values.
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*
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* R/Wi contains the type of the breakpoint /
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* watchpoint, LENi contains the length of the watched
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* data in the watchpoint case.
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*
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* The invalid values are:
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* - LENi == 0x10 (undefined), so mask |= 0x0f00.
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* - R/Wi == 0x10 (break on I/O reads or writes), so
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* mask |= 0x4444.
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* - R/Wi == 0x00 && LENi != 0x00, so we have mask |=
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* 0x1110.
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*
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* Finally, mask = 0x0f00 | 0x4444 | 0x1110 == 0x5f54.
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*
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* See the Intel Manual "System Programming Guide",
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* 15.2.4
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*
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* Note that LENi == 0x10 is defined on x86_64 in long
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* mode (i.e. even for 32-bit userspace software, but
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* 64-bit kernel), so the x86_64 mask value is 0x5454.
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* See the AMD manual no. 24593 (AMD64 System
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* Programming)*/
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if(addr == (long) &dummy->u_debugreg[7]) {
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data &= ~DR_CONTROL_RESERVED;
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for(i=0; i<4; i++)
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if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
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goto out_tsk;
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}
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addr -= (long) &dummy->u_debugreg;
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addr = addr >> 2;
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child->thread.debugreg[addr] = data;
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ret = 0;
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}
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break;
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case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
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case PTRACE_CONT: /* restart after signal. */
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ret = -EIO;
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if ((unsigned long) data > _NSIG)
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break;
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if (request == PTRACE_SYSCALL) {
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set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
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}
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else {
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clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
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}
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child->exit_code = data;
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/* make sure the single step bit is not set. */
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clear_singlestep(child);
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wake_up_process(child);
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ret = 0;
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break;
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/*
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* make the child exit. Best I can do is send it a sigkill.
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* perhaps it should be put in the status that it wants to
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* exit.
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*/
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case PTRACE_KILL:
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ret = 0;
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if (child->exit_state == EXIT_ZOMBIE) /* already dead */
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break;
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child->exit_code = SIGKILL;
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/* make sure the single step bit is not set. */
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clear_singlestep(child);
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wake_up_process(child);
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break;
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case PTRACE_SINGLESTEP: /* set the trap flag. */
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ret = -EIO;
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if ((unsigned long) data > _NSIG)
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break;
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clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
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set_singlestep(child);
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child->exit_code = data;
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/* give it a chance to run. */
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wake_up_process(child);
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ret = 0;
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break;
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case PTRACE_DETACH:
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/* detach a process that was attached. */
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ret = ptrace_detach(child, data);
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break;
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case PTRACE_GETREGS: { /* Get all gp regs from the child. */
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if (!access_ok(VERIFY_WRITE, datap, FRAME_SIZE*sizeof(long))) {
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ret = -EIO;
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break;
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}
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for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) {
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__put_user(getreg(child, i), datap);
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datap++;
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}
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ret = 0;
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break;
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}
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case PTRACE_SETREGS: { /* Set all gp regs in the child. */
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unsigned long tmp;
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if (!access_ok(VERIFY_READ, datap, FRAME_SIZE*sizeof(long))) {
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ret = -EIO;
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break;
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}
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for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) {
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__get_user(tmp, datap);
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putreg(child, i, tmp);
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datap++;
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}
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ret = 0;
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break;
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}
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case PTRACE_GETFPREGS: { /* Get the child FPU state. */
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if (!access_ok(VERIFY_WRITE, datap,
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sizeof(struct user_i387_struct))) {
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ret = -EIO;
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break;
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}
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ret = 0;
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if (!child->used_math)
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init_fpu(child);
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get_fpregs((struct user_i387_struct __user *)data, child);
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break;
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}
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case PTRACE_SETFPREGS: { /* Set the child FPU state. */
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if (!access_ok(VERIFY_READ, datap,
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sizeof(struct user_i387_struct))) {
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ret = -EIO;
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break;
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}
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child->used_math = 1;
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set_fpregs(child, (struct user_i387_struct __user *)data);
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ret = 0;
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break;
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}
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case PTRACE_GETFPXREGS: { /* Get the child extended FPU state. */
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if (!access_ok(VERIFY_WRITE, datap,
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sizeof(struct user_fxsr_struct))) {
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ret = -EIO;
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break;
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}
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if (!child->used_math)
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init_fpu(child);
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ret = get_fpxregs((struct user_fxsr_struct __user *)data, child);
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break;
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}
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case PTRACE_SETFPXREGS: { /* Set the child extended FPU state. */
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if (!access_ok(VERIFY_READ, datap,
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sizeof(struct user_fxsr_struct))) {
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ret = -EIO;
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break;
|
|
}
|
|
child->used_math = 1;
|
|
ret = set_fpxregs(child, (struct user_fxsr_struct __user *)data);
|
|
break;
|
|
}
|
|
|
|
case PTRACE_GET_THREAD_AREA:
|
|
ret = ptrace_get_thread_area(child, addr,
|
|
(struct user_desc __user *) data);
|
|
break;
|
|
|
|
case PTRACE_SET_THREAD_AREA:
|
|
ret = ptrace_set_thread_area(child, addr,
|
|
(struct user_desc __user *) data);
|
|
break;
|
|
|
|
default:
|
|
ret = ptrace_request(child, request, addr, data);
|
|
break;
|
|
}
|
|
out_tsk:
|
|
put_task_struct(child);
|
|
out:
|
|
unlock_kernel();
|
|
return ret;
|
|
}
|
|
|
|
/* notification of system call entry/exit
|
|
* - triggered by current->work.syscall_trace
|
|
*/
|
|
__attribute__((regparm(3)))
|
|
void do_syscall_trace(struct pt_regs *regs, int entryexit)
|
|
{
|
|
if (unlikely(current->audit_context)) {
|
|
if (!entryexit)
|
|
audit_syscall_entry(current, regs->orig_eax,
|
|
regs->ebx, regs->ecx,
|
|
regs->edx, regs->esi);
|
|
else
|
|
audit_syscall_exit(current, regs->eax);
|
|
}
|
|
|
|
if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
|
|
!test_thread_flag(TIF_SINGLESTEP))
|
|
return;
|
|
if (!(current->ptrace & PT_PTRACED))
|
|
return;
|
|
/* the 0x80 provides a way for the tracing parent to distinguish
|
|
between a syscall stop and SIGTRAP delivery */
|
|
ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) &&
|
|
!test_thread_flag(TIF_SINGLESTEP) ? 0x80 : 0));
|
|
|
|
/*
|
|
* this isn't the same as continuing with a signal, but it will do
|
|
* for normal use. strace only continues with a signal if the
|
|
* stopping signal is not SIGTRAP. -brl
|
|
*/
|
|
if (current->exit_code) {
|
|
send_sig(current->exit_code, current, 1);
|
|
current->exit_code = 0;
|
|
}
|
|
}
|