11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/kernel/ptrace.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * (C) Copyright 1999 Linus Torvalds 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Common interfaces for "ptrace()" which we do not want 71da177e4SLinus Torvalds * to continually duplicate across every architecture. 81da177e4SLinus Torvalds */ 91da177e4SLinus Torvalds 101da177e4SLinus Torvalds #include <linux/module.h> 111da177e4SLinus Torvalds #include <linux/sched.h> 121da177e4SLinus Torvalds #include <linux/errno.h> 131da177e4SLinus Torvalds #include <linux/mm.h> 141da177e4SLinus Torvalds #include <linux/highmem.h> 151da177e4SLinus Torvalds #include <linux/pagemap.h> 161da177e4SLinus Torvalds #include <linux/smp_lock.h> 171da177e4SLinus Torvalds #include <linux/ptrace.h> 181da177e4SLinus Torvalds #include <linux/security.h> 191da177e4SLinus Torvalds 201da177e4SLinus Torvalds #include <asm/pgtable.h> 211da177e4SLinus Torvalds #include <asm/uaccess.h> 221da177e4SLinus Torvalds 231da177e4SLinus Torvalds /* 241da177e4SLinus Torvalds * ptrace a task: make the debugger its new parent and 251da177e4SLinus Torvalds * move it to the ptrace list. 261da177e4SLinus Torvalds * 271da177e4SLinus Torvalds * Must be called with the tasklist lock write-held. 281da177e4SLinus Torvalds */ 291da177e4SLinus Torvalds void __ptrace_link(task_t *child, task_t *new_parent) 301da177e4SLinus Torvalds { 311da177e4SLinus Torvalds if (!list_empty(&child->ptrace_list)) 321da177e4SLinus Torvalds BUG(); 331da177e4SLinus Torvalds if (child->parent == new_parent) 341da177e4SLinus Torvalds return; 351da177e4SLinus Torvalds list_add(&child->ptrace_list, &child->parent->ptrace_children); 361da177e4SLinus Torvalds REMOVE_LINKS(child); 371da177e4SLinus Torvalds child->parent = new_parent; 381da177e4SLinus Torvalds SET_LINKS(child); 391da177e4SLinus Torvalds } 401da177e4SLinus Torvalds 411da177e4SLinus Torvalds /* 421da177e4SLinus Torvalds * Turn a tracing stop into a normal stop now, since with no tracer there 431da177e4SLinus Torvalds * would be no way to wake it up with SIGCONT or SIGKILL. If there was a 441da177e4SLinus Torvalds * signal sent that would resume the child, but didn't because it was in 451da177e4SLinus Torvalds * TASK_TRACED, resume it now. 461da177e4SLinus Torvalds * Requires that irqs be disabled. 471da177e4SLinus Torvalds */ 481da177e4SLinus Torvalds void ptrace_untrace(task_t *child) 491da177e4SLinus Torvalds { 501da177e4SLinus Torvalds spin_lock(&child->sighand->siglock); 511da177e4SLinus Torvalds if (child->state == TASK_TRACED) { 521da177e4SLinus Torvalds if (child->signal->flags & SIGNAL_STOP_STOPPED) { 531da177e4SLinus Torvalds child->state = TASK_STOPPED; 541da177e4SLinus Torvalds } else { 551da177e4SLinus Torvalds signal_wake_up(child, 1); 561da177e4SLinus Torvalds } 571da177e4SLinus Torvalds } 581da177e4SLinus Torvalds spin_unlock(&child->sighand->siglock); 591da177e4SLinus Torvalds } 601da177e4SLinus Torvalds 611da177e4SLinus Torvalds /* 621da177e4SLinus Torvalds * unptrace a task: move it back to its original parent and 631da177e4SLinus Torvalds * remove it from the ptrace list. 641da177e4SLinus Torvalds * 651da177e4SLinus Torvalds * Must be called with the tasklist lock write-held. 661da177e4SLinus Torvalds */ 671da177e4SLinus Torvalds void __ptrace_unlink(task_t *child) 681da177e4SLinus Torvalds { 691da177e4SLinus Torvalds if (!child->ptrace) 701da177e4SLinus Torvalds BUG(); 711da177e4SLinus Torvalds child->ptrace = 0; 721da177e4SLinus Torvalds if (!list_empty(&child->ptrace_list)) { 731da177e4SLinus Torvalds list_del_init(&child->ptrace_list); 741da177e4SLinus Torvalds REMOVE_LINKS(child); 751da177e4SLinus Torvalds child->parent = child->real_parent; 761da177e4SLinus Torvalds SET_LINKS(child); 771da177e4SLinus Torvalds } 781da177e4SLinus Torvalds 791da177e4SLinus Torvalds if (child->state == TASK_TRACED) 801da177e4SLinus Torvalds ptrace_untrace(child); 811da177e4SLinus Torvalds } 821da177e4SLinus Torvalds 831da177e4SLinus Torvalds /* 841da177e4SLinus Torvalds * Check that we have indeed attached to the thing.. 851da177e4SLinus Torvalds */ 861da177e4SLinus Torvalds int ptrace_check_attach(struct task_struct *child, int kill) 871da177e4SLinus Torvalds { 881da177e4SLinus Torvalds int ret = -ESRCH; 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds /* 911da177e4SLinus Torvalds * We take the read lock around doing both checks to close a 921da177e4SLinus Torvalds * possible race where someone else was tracing our child and 931da177e4SLinus Torvalds * detached between these two checks. After this locked check, 941da177e4SLinus Torvalds * we are sure that this is our traced child and that can only 951da177e4SLinus Torvalds * be changed by us so it's not changing right after this. 961da177e4SLinus Torvalds */ 971da177e4SLinus Torvalds read_lock(&tasklist_lock); 981da177e4SLinus Torvalds if ((child->ptrace & PT_PTRACED) && child->parent == current && 991da177e4SLinus Torvalds (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) 1001da177e4SLinus Torvalds && child->signal != NULL) { 1011da177e4SLinus Torvalds ret = 0; 1021da177e4SLinus Torvalds spin_lock_irq(&child->sighand->siglock); 1031da177e4SLinus Torvalds if (child->state == TASK_STOPPED) { 1041da177e4SLinus Torvalds child->state = TASK_TRACED; 1051da177e4SLinus Torvalds } else if (child->state != TASK_TRACED && !kill) { 1061da177e4SLinus Torvalds ret = -ESRCH; 1071da177e4SLinus Torvalds } 1081da177e4SLinus Torvalds spin_unlock_irq(&child->sighand->siglock); 1091da177e4SLinus Torvalds } 1101da177e4SLinus Torvalds read_unlock(&tasklist_lock); 1111da177e4SLinus Torvalds 1121da177e4SLinus Torvalds if (!ret && !kill) { 1131da177e4SLinus Torvalds wait_task_inactive(child); 1141da177e4SLinus Torvalds } 1151da177e4SLinus Torvalds 1161da177e4SLinus Torvalds /* All systems go.. */ 1171da177e4SLinus Torvalds return ret; 1181da177e4SLinus Torvalds } 1191da177e4SLinus Torvalds 1201da177e4SLinus Torvalds int ptrace_attach(struct task_struct *task) 1211da177e4SLinus Torvalds { 1221da177e4SLinus Torvalds int retval; 1231da177e4SLinus Torvalds task_lock(task); 1241da177e4SLinus Torvalds retval = -EPERM; 1251da177e4SLinus Torvalds if (task->pid <= 1) 1261da177e4SLinus Torvalds goto bad; 1271da177e4SLinus Torvalds if (task == current) 1281da177e4SLinus Torvalds goto bad; 1291da177e4SLinus Torvalds if (!task->mm) 1301da177e4SLinus Torvalds goto bad; 1311da177e4SLinus Torvalds if(((current->uid != task->euid) || 1321da177e4SLinus Torvalds (current->uid != task->suid) || 1331da177e4SLinus Torvalds (current->uid != task->uid) || 1341da177e4SLinus Torvalds (current->gid != task->egid) || 1351da177e4SLinus Torvalds (current->gid != task->sgid) || 1361da177e4SLinus Torvalds (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) 1371da177e4SLinus Torvalds goto bad; 1381da177e4SLinus Torvalds rmb(); 1391da177e4SLinus Torvalds if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE)) 1401da177e4SLinus Torvalds goto bad; 1411da177e4SLinus Torvalds /* the same process cannot be attached many times */ 1421da177e4SLinus Torvalds if (task->ptrace & PT_PTRACED) 1431da177e4SLinus Torvalds goto bad; 1441da177e4SLinus Torvalds retval = security_ptrace(current, task); 1451da177e4SLinus Torvalds if (retval) 1461da177e4SLinus Torvalds goto bad; 1471da177e4SLinus Torvalds 1481da177e4SLinus Torvalds /* Go */ 1491da177e4SLinus Torvalds task->ptrace |= PT_PTRACED | ((task->real_parent != current) 1501da177e4SLinus Torvalds ? PT_ATTACHED : 0); 1511da177e4SLinus Torvalds if (capable(CAP_SYS_PTRACE)) 1521da177e4SLinus Torvalds task->ptrace |= PT_PTRACE_CAP; 1531da177e4SLinus Torvalds task_unlock(task); 1541da177e4SLinus Torvalds 1551da177e4SLinus Torvalds write_lock_irq(&tasklist_lock); 1561da177e4SLinus Torvalds __ptrace_link(task, current); 1571da177e4SLinus Torvalds write_unlock_irq(&tasklist_lock); 1581da177e4SLinus Torvalds 1591da177e4SLinus Torvalds force_sig_specific(SIGSTOP, task); 1601da177e4SLinus Torvalds return 0; 1611da177e4SLinus Torvalds 1621da177e4SLinus Torvalds bad: 1631da177e4SLinus Torvalds task_unlock(task); 1641da177e4SLinus Torvalds return retval; 1651da177e4SLinus Torvalds } 1661da177e4SLinus Torvalds 1671da177e4SLinus Torvalds int ptrace_detach(struct task_struct *child, unsigned int data) 1681da177e4SLinus Torvalds { 1691da177e4SLinus Torvalds if ((unsigned long) data > _NSIG) 1701da177e4SLinus Torvalds return -EIO; 1711da177e4SLinus Torvalds 1721da177e4SLinus Torvalds /* Architecture-specific hardware disable .. */ 1731da177e4SLinus Torvalds ptrace_disable(child); 1741da177e4SLinus Torvalds 1751da177e4SLinus Torvalds /* .. re-parent .. */ 1761da177e4SLinus Torvalds child->exit_code = data; 1771da177e4SLinus Torvalds 1781da177e4SLinus Torvalds write_lock_irq(&tasklist_lock); 1791da177e4SLinus Torvalds __ptrace_unlink(child); 1801da177e4SLinus Torvalds /* .. and wake it up. */ 1811da177e4SLinus Torvalds if (child->exit_state != EXIT_ZOMBIE) 1821da177e4SLinus Torvalds wake_up_process(child); 1831da177e4SLinus Torvalds write_unlock_irq(&tasklist_lock); 1841da177e4SLinus Torvalds 1851da177e4SLinus Torvalds return 0; 1861da177e4SLinus Torvalds } 1871da177e4SLinus Torvalds 1881da177e4SLinus Torvalds /* 1891da177e4SLinus Torvalds * Access another process' address space. 1901da177e4SLinus Torvalds * Source/target buffer must be kernel space, 1911da177e4SLinus Torvalds * Do not walk the page table directly, use get_user_pages 1921da177e4SLinus Torvalds */ 1931da177e4SLinus Torvalds 1941da177e4SLinus Torvalds int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 1951da177e4SLinus Torvalds { 1961da177e4SLinus Torvalds struct mm_struct *mm; 1971da177e4SLinus Torvalds struct vm_area_struct *vma; 1981da177e4SLinus Torvalds struct page *page; 1991da177e4SLinus Torvalds void *old_buf = buf; 2001da177e4SLinus Torvalds 2011da177e4SLinus Torvalds mm = get_task_mm(tsk); 2021da177e4SLinus Torvalds if (!mm) 2031da177e4SLinus Torvalds return 0; 2041da177e4SLinus Torvalds 2051da177e4SLinus Torvalds down_read(&mm->mmap_sem); 2061da177e4SLinus Torvalds /* ignore errors, just check how much was sucessfully transfered */ 2071da177e4SLinus Torvalds while (len) { 2081da177e4SLinus Torvalds int bytes, ret, offset; 2091da177e4SLinus Torvalds void *maddr; 2101da177e4SLinus Torvalds 2111da177e4SLinus Torvalds ret = get_user_pages(tsk, mm, addr, 1, 2121da177e4SLinus Torvalds write, 1, &page, &vma); 2131da177e4SLinus Torvalds if (ret <= 0) 2141da177e4SLinus Torvalds break; 2151da177e4SLinus Torvalds 2161da177e4SLinus Torvalds bytes = len; 2171da177e4SLinus Torvalds offset = addr & (PAGE_SIZE-1); 2181da177e4SLinus Torvalds if (bytes > PAGE_SIZE-offset) 2191da177e4SLinus Torvalds bytes = PAGE_SIZE-offset; 2201da177e4SLinus Torvalds 2211da177e4SLinus Torvalds maddr = kmap(page); 2221da177e4SLinus Torvalds if (write) { 2231da177e4SLinus Torvalds copy_to_user_page(vma, page, addr, 2241da177e4SLinus Torvalds maddr + offset, buf, bytes); 2251da177e4SLinus Torvalds set_page_dirty_lock(page); 2261da177e4SLinus Torvalds } else { 2271da177e4SLinus Torvalds copy_from_user_page(vma, page, addr, 2281da177e4SLinus Torvalds buf, maddr + offset, bytes); 2291da177e4SLinus Torvalds } 2301da177e4SLinus Torvalds kunmap(page); 2311da177e4SLinus Torvalds page_cache_release(page); 2321da177e4SLinus Torvalds len -= bytes; 2331da177e4SLinus Torvalds buf += bytes; 2341da177e4SLinus Torvalds addr += bytes; 2351da177e4SLinus Torvalds } 2361da177e4SLinus Torvalds up_read(&mm->mmap_sem); 2371da177e4SLinus Torvalds mmput(mm); 2381da177e4SLinus Torvalds 2391da177e4SLinus Torvalds return buf - old_buf; 2401da177e4SLinus Torvalds } 2411da177e4SLinus Torvalds 2421da177e4SLinus Torvalds int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) 2431da177e4SLinus Torvalds { 2441da177e4SLinus Torvalds int copied = 0; 2451da177e4SLinus Torvalds 2461da177e4SLinus Torvalds while (len > 0) { 2471da177e4SLinus Torvalds char buf[128]; 2481da177e4SLinus Torvalds int this_len, retval; 2491da177e4SLinus Torvalds 2501da177e4SLinus Torvalds this_len = (len > sizeof(buf)) ? sizeof(buf) : len; 2511da177e4SLinus Torvalds retval = access_process_vm(tsk, src, buf, this_len, 0); 2521da177e4SLinus Torvalds if (!retval) { 2531da177e4SLinus Torvalds if (copied) 2541da177e4SLinus Torvalds break; 2551da177e4SLinus Torvalds return -EIO; 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds if (copy_to_user(dst, buf, retval)) 2581da177e4SLinus Torvalds return -EFAULT; 2591da177e4SLinus Torvalds copied += retval; 2601da177e4SLinus Torvalds src += retval; 2611da177e4SLinus Torvalds dst += retval; 2621da177e4SLinus Torvalds len -= retval; 2631da177e4SLinus Torvalds } 2641da177e4SLinus Torvalds return copied; 2651da177e4SLinus Torvalds } 2661da177e4SLinus Torvalds 2671da177e4SLinus Torvalds int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) 2681da177e4SLinus Torvalds { 2691da177e4SLinus Torvalds int copied = 0; 2701da177e4SLinus Torvalds 2711da177e4SLinus Torvalds while (len > 0) { 2721da177e4SLinus Torvalds char buf[128]; 2731da177e4SLinus Torvalds int this_len, retval; 2741da177e4SLinus Torvalds 2751da177e4SLinus Torvalds this_len = (len > sizeof(buf)) ? sizeof(buf) : len; 2761da177e4SLinus Torvalds if (copy_from_user(buf, src, this_len)) 2771da177e4SLinus Torvalds return -EFAULT; 2781da177e4SLinus Torvalds retval = access_process_vm(tsk, dst, buf, this_len, 1); 2791da177e4SLinus Torvalds if (!retval) { 2801da177e4SLinus Torvalds if (copied) 2811da177e4SLinus Torvalds break; 2821da177e4SLinus Torvalds return -EIO; 2831da177e4SLinus Torvalds } 2841da177e4SLinus Torvalds copied += retval; 2851da177e4SLinus Torvalds src += retval; 2861da177e4SLinus Torvalds dst += retval; 2871da177e4SLinus Torvalds len -= retval; 2881da177e4SLinus Torvalds } 2891da177e4SLinus Torvalds return copied; 2901da177e4SLinus Torvalds } 2911da177e4SLinus Torvalds 2921da177e4SLinus Torvalds static int ptrace_setoptions(struct task_struct *child, long data) 2931da177e4SLinus Torvalds { 2941da177e4SLinus Torvalds child->ptrace &= ~PT_TRACE_MASK; 2951da177e4SLinus Torvalds 2961da177e4SLinus Torvalds if (data & PTRACE_O_TRACESYSGOOD) 2971da177e4SLinus Torvalds child->ptrace |= PT_TRACESYSGOOD; 2981da177e4SLinus Torvalds 2991da177e4SLinus Torvalds if (data & PTRACE_O_TRACEFORK) 3001da177e4SLinus Torvalds child->ptrace |= PT_TRACE_FORK; 3011da177e4SLinus Torvalds 3021da177e4SLinus Torvalds if (data & PTRACE_O_TRACEVFORK) 3031da177e4SLinus Torvalds child->ptrace |= PT_TRACE_VFORK; 3041da177e4SLinus Torvalds 3051da177e4SLinus Torvalds if (data & PTRACE_O_TRACECLONE) 3061da177e4SLinus Torvalds child->ptrace |= PT_TRACE_CLONE; 3071da177e4SLinus Torvalds 3081da177e4SLinus Torvalds if (data & PTRACE_O_TRACEEXEC) 3091da177e4SLinus Torvalds child->ptrace |= PT_TRACE_EXEC; 3101da177e4SLinus Torvalds 3111da177e4SLinus Torvalds if (data & PTRACE_O_TRACEVFORKDONE) 3121da177e4SLinus Torvalds child->ptrace |= PT_TRACE_VFORK_DONE; 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds if (data & PTRACE_O_TRACEEXIT) 3151da177e4SLinus Torvalds child->ptrace |= PT_TRACE_EXIT; 3161da177e4SLinus Torvalds 3171da177e4SLinus Torvalds return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; 3181da177e4SLinus Torvalds } 3191da177e4SLinus Torvalds 3201da177e4SLinus Torvalds static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data) 3211da177e4SLinus Torvalds { 3221da177e4SLinus Torvalds siginfo_t lastinfo; 3231da177e4SLinus Torvalds int error = -ESRCH; 3241da177e4SLinus Torvalds 3251da177e4SLinus Torvalds read_lock(&tasklist_lock); 3261da177e4SLinus Torvalds if (likely(child->sighand != NULL)) { 3271da177e4SLinus Torvalds error = -EINVAL; 3281da177e4SLinus Torvalds spin_lock_irq(&child->sighand->siglock); 3291da177e4SLinus Torvalds if (likely(child->last_siginfo != NULL)) { 3301da177e4SLinus Torvalds lastinfo = *child->last_siginfo; 3311da177e4SLinus Torvalds error = 0; 3321da177e4SLinus Torvalds } 3331da177e4SLinus Torvalds spin_unlock_irq(&child->sighand->siglock); 3341da177e4SLinus Torvalds } 3351da177e4SLinus Torvalds read_unlock(&tasklist_lock); 3361da177e4SLinus Torvalds if (!error) 3371da177e4SLinus Torvalds return copy_siginfo_to_user(data, &lastinfo); 3381da177e4SLinus Torvalds return error; 3391da177e4SLinus Torvalds } 3401da177e4SLinus Torvalds 3411da177e4SLinus Torvalds static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data) 3421da177e4SLinus Torvalds { 3431da177e4SLinus Torvalds siginfo_t newinfo; 3441da177e4SLinus Torvalds int error = -ESRCH; 3451da177e4SLinus Torvalds 3461da177e4SLinus Torvalds if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) 3471da177e4SLinus Torvalds return -EFAULT; 3481da177e4SLinus Torvalds 3491da177e4SLinus Torvalds read_lock(&tasklist_lock); 3501da177e4SLinus Torvalds if (likely(child->sighand != NULL)) { 3511da177e4SLinus Torvalds error = -EINVAL; 3521da177e4SLinus Torvalds spin_lock_irq(&child->sighand->siglock); 3531da177e4SLinus Torvalds if (likely(child->last_siginfo != NULL)) { 3541da177e4SLinus Torvalds *child->last_siginfo = newinfo; 3551da177e4SLinus Torvalds error = 0; 3561da177e4SLinus Torvalds } 3571da177e4SLinus Torvalds spin_unlock_irq(&child->sighand->siglock); 3581da177e4SLinus Torvalds } 3591da177e4SLinus Torvalds read_unlock(&tasklist_lock); 3601da177e4SLinus Torvalds return error; 3611da177e4SLinus Torvalds } 3621da177e4SLinus Torvalds 3631da177e4SLinus Torvalds int ptrace_request(struct task_struct *child, long request, 3641da177e4SLinus Torvalds long addr, long data) 3651da177e4SLinus Torvalds { 3661da177e4SLinus Torvalds int ret = -EIO; 3671da177e4SLinus Torvalds 3681da177e4SLinus Torvalds switch (request) { 3691da177e4SLinus Torvalds #ifdef PTRACE_OLDSETOPTIONS 3701da177e4SLinus Torvalds case PTRACE_OLDSETOPTIONS: 3711da177e4SLinus Torvalds #endif 3721da177e4SLinus Torvalds case PTRACE_SETOPTIONS: 3731da177e4SLinus Torvalds ret = ptrace_setoptions(child, data); 3741da177e4SLinus Torvalds break; 3751da177e4SLinus Torvalds case PTRACE_GETEVENTMSG: 3761da177e4SLinus Torvalds ret = put_user(child->ptrace_message, (unsigned long __user *) data); 3771da177e4SLinus Torvalds break; 3781da177e4SLinus Torvalds case PTRACE_GETSIGINFO: 3791da177e4SLinus Torvalds ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); 3801da177e4SLinus Torvalds break; 3811da177e4SLinus Torvalds case PTRACE_SETSIGINFO: 3821da177e4SLinus Torvalds ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); 3831da177e4SLinus Torvalds break; 3841da177e4SLinus Torvalds default: 3851da177e4SLinus Torvalds break; 3861da177e4SLinus Torvalds } 3871da177e4SLinus Torvalds 3881da177e4SLinus Torvalds return ret; 3891da177e4SLinus Torvalds } 390