/* ptrace.c */ /* By Ross Biro 1/23/92 */ /* * Pentium III FXSR, SSE support * Gareth Hughes , May 2000 */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * does not yet catch signals sent when the child dies. * in exit.c or in signal.c. */ /* determines which flags the user has access to. */ /* 1 = access 0 = no access */ #define FLAG_MASK 0x00044dd5 /* set's the trap flag. */ #define TRAP_FLAG 0x100 /* * Offset of eflags on child stack.. */ #define EFL_OFFSET ((EFL-2)*4-sizeof(struct pt_regs)) static inline struct pt_regs *get_child_regs(struct task_struct *task) { void *stack_top = (void *)task->thread.esp0; return stack_top - sizeof(struct pt_regs); } /* * this routine will get a word off of the processes privileged stack. * the offset is how far from the base addr as stored in the TSS. * this routine assumes that all the privileged stacks are in our * data space. */ static inline int get_stack_long(struct task_struct *task, int offset) { unsigned char *stack; stack = (unsigned char *)task->thread.esp0; stack += offset; return (*((int *)stack)); } /* * this routine will put a word on the processes privileged stack. * the offset is how far from the base addr as stored in the TSS. * this routine assumes that all the privileged stacks are in our * data space. */ static inline int put_stack_long(struct task_struct *task, int offset, unsigned long data) { unsigned char * stack; stack = (unsigned char *) task->thread.esp0; stack += offset; *(unsigned long *) stack = data; return 0; } static int putreg(struct task_struct *child, unsigned long regno, unsigned long value) { switch (regno >> 2) { case FS: if (value && (value & 3) != 3) return -EIO; child->thread.fs = value; return 0; case GS: if (value && (value & 3) != 3) return -EIO; child->thread.gs = value; return 0; case DS: case ES: if (value && (value & 3) != 3) return -EIO; value &= 0xffff; break; case SS: case CS: if ((value & 3) != 3) return -EIO; value &= 0xffff; break; case EFL: value &= FLAG_MASK; value |= get_stack_long(child, EFL_OFFSET) & ~FLAG_MASK; break; } if (regno > GS*4) regno -= 2*4; put_stack_long(child, regno - sizeof(struct pt_regs), value); return 0; } static unsigned long getreg(struct task_struct *child, unsigned long regno) { unsigned long retval = ~0UL; switch (regno >> 2) { case FS: retval = child->thread.fs; break; case GS: retval = child->thread.gs; break; case DS: case ES: case SS: case CS: retval = 0xffff; /* fall through */ default: if (regno > GS*4) regno -= 2*4; regno = regno - sizeof(struct pt_regs); retval &= get_stack_long(child, regno); } return retval; } #define LDT_SEGMENT 4 static unsigned long convert_eip_to_linear(struct task_struct *child, struct pt_regs *regs) { unsigned long addr, seg; addr = regs->eip; seg = regs->xcs & 0xffff; if (regs->eflags & VM_MASK) { addr = (addr & 0xffff) + (seg << 4); return addr; } /* * We'll assume that the code segments in the GDT * are all zero-based. That is largely true: the * TLS segments are used for data, and the PNPBIOS * and APM bios ones we just ignore here. */ if (seg & LDT_SEGMENT) { u32 *desc; unsigned long base; down(&child->mm->context.sem); desc = child->mm->context.ldt + (seg & ~7); base = (desc[0] >> 16) | ((desc[1] & 0xff) << 16) | (desc[1] & 0xff000000); /* 16-bit code segment? */ if (!((desc[1] >> 22) & 1)) addr &= 0xffff; addr += base; up(&child->mm->context.sem); } return addr; } static inline int is_at_popf(struct task_struct *child, struct pt_regs *regs) { int i, copied; unsigned char opcode[16]; unsigned long addr = convert_eip_to_linear(child, regs); copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0); for (i = 0; i < copied; i++) { switch (opcode[i]) { /* popf */ case 0x9d: return 1; /* opcode and address size prefixes */ case 0x66: case 0x67: continue; /* irrelevant prefixes (segment overrides and repeats) */ case 0x26: case 0x2e: case 0x36: case 0x3e: case 0x64: case 0x65: case 0xf0: case 0xf2: case 0xf3: continue; /* * pushf: NOTE! We should probably not let * the user see the TF bit being set. But * it's more pain than it's worth to avoid * it, and a debugger could emulate this * all in user space if it _really_ cares. */ case 0x9c: default: return 0; } } return 0; } static void set_singlestep(struct task_struct *child) { struct pt_regs *regs = get_child_regs(child); /* * Always set TIF_SINGLESTEP - this guarantees that * we single-step system calls etc.. This will also * cause us to set TF when returning to user mode. */ set_tsk_thread_flag(child, TIF_SINGLESTEP); /* * If TF was already set, don't do anything else */ if (regs->eflags & TRAP_FLAG) return; /* Set TF on the kernel stack.. */ regs->eflags |= TRAP_FLAG; /* * ..but if TF is changed by the instruction we will trace, * don't mark it as being "us" that set it, so that we * won't clear it by hand later. */ if (is_at_popf(child, regs)) return; child->ptrace |= PT_DTRACE; } static void clear_singlestep(struct task_struct *child) { /* Always clear TIF_SINGLESTEP... */ clear_tsk_thread_flag(child, TIF_SINGLESTEP); /* But touch TF only if it was set by us.. */ if (child->ptrace & PT_DTRACE) { struct pt_regs *regs = get_child_regs(child); regs->eflags &= ~TRAP_FLAG; child->ptrace &= ~PT_DTRACE; } } /* * Called by kernel/ptrace.c when detaching.. * * Make sure the single step bit is not set. */ void ptrace_disable(struct task_struct *child) { clear_singlestep(child); } /* * Perform get_thread_area on behalf of the traced child. */ static int ptrace_get_thread_area(struct task_struct *child, int idx, struct user_desc __user *user_desc) { struct user_desc info; struct desc_struct *desc; /* * Get the current Thread-Local Storage area: */ #define GET_BASE(desc) ( \ (((desc)->a >> 16) & 0x0000ffff) | \ (((desc)->b << 16) & 0x00ff0000) | \ ( (desc)->b & 0xff000000) ) #define GET_LIMIT(desc) ( \ ((desc)->a & 0x0ffff) | \ ((desc)->b & 0xf0000) ) #define GET_32BIT(desc) (((desc)->b >> 22) & 1) #define GET_CONTENTS(desc) (((desc)->b >> 10) & 3) #define GET_WRITABLE(desc) (((desc)->b >> 9) & 1) #define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1) #define GET_PRESENT(desc) (((desc)->b >> 15) & 1) #define GET_USEABLE(desc) (((desc)->b >> 20) & 1) if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) return -EINVAL; desc = child->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; info.entry_number = idx; info.base_addr = GET_BASE(desc); info.limit = GET_LIMIT(desc); info.seg_32bit = GET_32BIT(desc); info.contents = GET_CONTENTS(desc); info.read_exec_only = !GET_WRITABLE(desc); info.limit_in_pages = GET_LIMIT_PAGES(desc); info.seg_not_present = !GET_PRESENT(desc); info.useable = GET_USEABLE(desc); if (copy_to_user(user_desc, &info, sizeof(info))) return -EFAULT; return 0; } /* * Perform set_thread_area on behalf of the traced child. */ static int ptrace_set_thread_area(struct task_struct *child, int idx, struct user_desc __user *user_desc) { struct user_desc info; struct desc_struct *desc; if (copy_from_user(&info, user_desc, sizeof(info))) return -EFAULT; if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) return -EINVAL; desc = child->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; if (LDT_empty(&info)) { desc->a = 0; desc->b = 0; } else { desc->a = LDT_entry_a(&info); desc->b = LDT_entry_b(&info); } return 0; } asmlinkage int sys_ptrace(long request, long pid, long addr, long data) { struct task_struct *child; struct user * dummy = NULL; int i, ret; unsigned long __user *datap = (unsigned long __user *)data; lock_kernel(); ret = -EPERM; if (request == PTRACE_TRACEME) { /* are we already being traced? */ if (current->ptrace & PT_PTRACED) goto out; ret = security_ptrace(current->parent, current); if (ret) goto out; /* set the ptrace bit in the process flags. */ current->ptrace |= PT_PTRACED; ret = 0; goto out; } ret = -ESRCH; read_lock(&tasklist_lock); child = find_task_by_pid(pid); if (child) get_task_struct(child); read_unlock(&tasklist_lock); if (!child) goto out; ret = -EPERM; if (pid == 1) /* you may not mess with init */ goto out_tsk; if (request == PTRACE_ATTACH) { ret = ptrace_attach(child); goto out_tsk; } ret = ptrace_check_attach(child, request == PTRACE_KILL); if (ret < 0) goto out_tsk; switch (request) { /* when I and D space are separate, these will need to be fixed. */ case PTRACE_PEEKTEXT: /* read word at location addr. */ case PTRACE_PEEKDATA: { unsigned long tmp; int copied; copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); ret = -EIO; if (copied != sizeof(tmp)) break; ret = put_user(tmp, datap); break; } /* read the word at location addr in the USER area. */ case PTRACE_PEEKUSR: { unsigned long tmp; ret = -EIO; if ((addr & 3) || addr < 0 || addr > sizeof(struct user) - 3) break; tmp = 0; /* Default return condition */ if(addr < FRAME_SIZE*sizeof(long)) tmp = getreg(child, addr); if(addr >= (long) &dummy->u_debugreg[0] && addr <= (long) &dummy->u_debugreg[7]){ addr -= (long) &dummy->u_debugreg[0]; addr = addr >> 2; tmp = child->thread.debugreg[addr]; } ret = put_user(tmp, datap); break; } /* when I and D space are separate, this will have to be fixed. */ case PTRACE_POKETEXT: /* write the word at location addr. */ case PTRACE_POKEDATA: ret = 0; if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data)) break; ret = -EIO; break; case PTRACE_POKEUSR: /* write the word at location addr in the USER area */ ret = -EIO; if ((addr & 3) || addr < 0 || addr > sizeof(struct user) - 3) break; if (addr < FRAME_SIZE*sizeof(long)) { ret = putreg(child, addr, data); break; } /* We need to be very careful here. We implicitly want to modify a portion of the task_struct, and we have to be selective about what portions we allow someone to modify. */ ret = -EIO; if(addr >= (long) &dummy->u_debugreg[0] && addr <= (long) &dummy->u_debugreg[7]){ if(addr == (long) &dummy->u_debugreg[4]) break; if(addr == (long) &dummy->u_debugreg[5]) break; if(addr < (long) &dummy->u_debugreg[4] && ((unsigned long) data) >= TASK_SIZE-3) break; /* Sanity-check data. Take one half-byte at once with * check = (val >> (16 + 4*i)) & 0xf. It contains the * R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits * 2 and 3 are LENi. Given a list of invalid values, * we do mask |= 1 << invalid_value, so that * (mask >> check) & 1 is a correct test for invalid * values. * * R/Wi contains the type of the breakpoint / * watchpoint, LENi contains the length of the watched * data in the watchpoint case. * * The invalid values are: * - LENi == 0x10 (undefined), so mask |= 0x0f00. * - R/Wi == 0x10 (break on I/O reads or writes), so * mask |= 0x4444. * - R/Wi == 0x00 && LENi != 0x00, so we have mask |= * 0x1110. * * Finally, mask = 0x0f00 | 0x4444 | 0x1110 == 0x5f54. * * See the Intel Manual "System Programming Guide", * 15.2.4 * * Note that LENi == 0x10 is defined on x86_64 in long * mode (i.e. even for 32-bit userspace software, but * 64-bit kernel), so the x86_64 mask value is 0x5454. * See the AMD manual no. 24593 (AMD64 System * Programming)*/ if(addr == (long) &dummy->u_debugreg[7]) { data &= ~DR_CONTROL_RESERVED; for(i=0; i<4; i++) if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1) goto out_tsk; } addr -= (long) &dummy->u_debugreg; addr = addr >> 2; child->thread.debugreg[addr] = data; ret = 0; } break; case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */ case PTRACE_CONT: /* restart after signal. */ ret = -EIO; if (!valid_signal(data)) break; if (request == PTRACE_SYSCALL) { set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); } else { clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); } child->exit_code = data; /* make sure the single step bit is not set. */ clear_singlestep(child); wake_up_process(child); ret = 0; break; /* * make the child exit. Best I can do is send it a sigkill. * perhaps it should be put in the status that it wants to * exit. */ case PTRACE_KILL: ret = 0; if (child->exit_state == EXIT_ZOMBIE) /* already dead */ break; child->exit_code = SIGKILL; /* make sure the single step bit is not set. */ clear_singlestep(child); wake_up_process(child); break; case PTRACE_SINGLESTEP: /* set the trap flag. */ ret = -EIO; if (!valid_signal(data)) break; clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); set_singlestep(child); child->exit_code = data; /* give it a chance to run. */ wake_up_process(child); ret = 0; break; case PTRACE_DETACH: /* detach a process that was attached. */ ret = ptrace_detach(child, data); break; case PTRACE_GETREGS: { /* Get all gp regs from the child. */ if (!access_ok(VERIFY_WRITE, datap, FRAME_SIZE*sizeof(long))) { ret = -EIO; break; } for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) { __put_user(getreg(child, i), datap); datap++; } ret = 0; break; } case PTRACE_SETREGS: { /* Set all gp regs in the child. */ unsigned long tmp; if (!access_ok(VERIFY_READ, datap, FRAME_SIZE*sizeof(long))) { ret = -EIO; break; } for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) { __get_user(tmp, datap); putreg(child, i, tmp); datap++; } ret = 0; break; } case PTRACE_GETFPREGS: { /* Get the child FPU state. */ if (!access_ok(VERIFY_WRITE, datap, sizeof(struct user_i387_struct))) { ret = -EIO; break; } ret = 0; if (!tsk_used_math(child)) init_fpu(child); get_fpregs((struct user_i387_struct __user *)data, child); break; } case PTRACE_SETFPREGS: { /* Set the child FPU state. */ if (!access_ok(VERIFY_READ, datap, sizeof(struct user_i387_struct))) { ret = -EIO; break; } set_stopped_child_used_math(child); set_fpregs(child, (struct user_i387_struct __user *)data); ret = 0; break; } case PTRACE_GETFPXREGS: { /* Get the child extended FPU state. */ if (!access_ok(VERIFY_WRITE, datap, sizeof(struct user_fxsr_struct))) { ret = -EIO; break; } if (!tsk_used_math(child)) init_fpu(child); ret = get_fpxregs((struct user_fxsr_struct __user *)data, child); break; } case PTRACE_SETFPXREGS: { /* Set the child extended FPU state. */ if (!access_ok(VERIFY_READ, datap, sizeof(struct user_fxsr_struct))) { ret = -EIO; break; } set_stopped_child_used_math(child); 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; } void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code) { struct siginfo info; tsk->thread.trap_no = 1; tsk->thread.error_code = error_code; memset(&info, 0, sizeof(info)); info.si_signo = SIGTRAP; info.si_code = TRAP_BRKPT; /* User-mode eip? */ info.si_addr = user_mode_vm(regs) ? (void __user *) regs->eip : NULL; /* Send us the fakey SIGTRAP */ force_sig_info(SIGTRAP, &info, tsk); } /* 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) { /* do the secure computing check first */ secure_computing(regs->orig_eax); if (unlikely(current->audit_context)) { if (entryexit) audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax); /* Debug traps, when using PTRACE_SINGLESTEP, must be sent only * on the syscall exit path. Normally, when TIF_SYSCALL_AUDIT is * not used, entry.S will call us only on syscall exit, not * entry ; so when TIF_SYSCALL_AUDIT is used we must avoid * calling send_sigtrap() on syscall entry. */ else if (is_singlestep) goto out; } if (!(current->ptrace & PT_PTRACED)) goto out; /* Fake a debug trap */ if (test_thread_flag(TIF_SINGLESTEP)) send_sigtrap(current, regs, 0); if (!test_thread_flag(TIF_SYSCALL_TRACE)) goto out; /* 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) ? 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; } out: if (unlikely(current->audit_context) && !entryexit) audit_syscall_entry(current, AUDIT_ARCH_I386, regs->orig_eax, regs->ebx, regs->ecx, regs->edx, regs->esi); }