Restore the old kernel/ptrace.c. ---
kernel/ptrace.c | 764 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 764 insertions(+) --- /dev/null 2009-11-21 14:04:55.632015473 +0100 +++ UTRACE-PTRACE/kernel/ptrace.c 2009-09-24 21:38:54.000000000 +0200 @@ -0,0 +1,764 @@ +/* + * linux/kernel/ptrace.c + * + * (C) Copyright 1999 Linus Torvalds + * + * Common interfaces for "ptrace()" which we do not want + * to continually duplicate across every architecture. + */ + +#include <linux/capability.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/errno.h> +#include <linux/mm.h> +#include <linux/highmem.h> +#include <linux/pagemap.h> +#include <linux/smp_lock.h> +#include <linux/ptrace.h> +#include <linux/security.h> +#include <linux/signal.h> +#include <linux/audit.h> +#include <linux/pid_namespace.h> +#include <linux/syscalls.h> +#include <linux/uaccess.h> + + +/* + * ptrace a task: make the debugger its new parent and + * move it to the ptrace list. + * + * Must be called with the tasklist lock write-held. + */ +void __ptrace_link(struct task_struct *child, struct task_struct *new_parent) +{ + BUG_ON(!list_empty(&child->ptrace_entry)); + list_add(&child->ptrace_entry, &new_parent->ptraced); + child->parent = new_parent; +} + +/* + * Turn a tracing stop into a normal stop now, since with no tracer there + * would be no way to wake it up with SIGCONT or SIGKILL. If there was a + * signal sent that would resume the child, but didn't because it was in + * TASK_TRACED, resume it now. + * Requires that irqs be disabled. + */ +static void ptrace_untrace(struct task_struct *child) +{ + spin_lock(&child->sighand->siglock); + if (task_is_traced(child)) { + /* + * If the group stop is completed or in progress, + * this thread was already counted as stopped. + */ + if (child->signal->flags & SIGNAL_STOP_STOPPED || + child->signal->group_stop_count) + __set_task_state(child, TASK_STOPPED); + else + signal_wake_up(child, 1); + } + spin_unlock(&child->sighand->siglock); +} + +/* + * unptrace a task: move it back to its original parent and + * remove it from the ptrace list. + * + * Must be called with the tasklist lock write-held. + */ +void __ptrace_unlink(struct task_struct *child) +{ + BUG_ON(!child->ptrace); + + child->ptrace = 0; + child->parent = child->real_parent; + list_del_init(&child->ptrace_entry); + + arch_ptrace_untrace(child); + if (task_is_traced(child)) + ptrace_untrace(child); +} + +/* + * Check that we have indeed attached to the thing.. + */ +int ptrace_check_attach(struct task_struct *child, int kill) +{ + int ret = -ESRCH; + + /* + * We take the read lock around doing both checks to close a + * possible race where someone else was tracing our child and + * detached between these two checks. After this locked check, + * we are sure that this is our traced child and that can only + * be changed by us so it's not changing right after this. + */ + read_lock(&tasklist_lock); + if ((child->ptrace & PT_PTRACED) && child->parent == current) { + ret = 0; + /* + * child->sighand can't be NULL, release_task() + * does ptrace_unlink() before __exit_signal(). + */ + spin_lock_irq(&child->sighand->siglock); + if (task_is_stopped(child)) + child->state = TASK_TRACED; + else if (!task_is_traced(child) && !kill) + ret = -ESRCH; + spin_unlock_irq(&child->sighand->siglock); + } + read_unlock(&tasklist_lock); + + if (!ret && !kill) + ret = wait_task_inactive(child, TASK_TRACED) ? 0 : -ESRCH; + + /* All systems go.. */ + return ret; +} + +int __ptrace_may_access(struct task_struct *task, unsigned int mode) +{ + const struct cred *cred = current_cred(), *tcred; + + /* May we inspect the given task? + * This check is used both for attaching with ptrace + * and for allowing access to sensitive information in /proc. + * + * ptrace_attach denies several cases that /proc allows + * because setting up the necessary parent/child relationship + * or halting the specified task is impossible. + */ + int dumpable = 0; + /* Don't let security modules deny introspection */ + if (task == current) + return 0; + rcu_read_lock(); + tcred = __task_cred(task); + if ((cred->uid != tcred->euid || + cred->uid != tcred->suid || + cred->uid != tcred->uid || + cred->gid != tcred->egid || + cred->gid != tcred->sgid || + cred->gid != tcred->gid) && + !capable(CAP_SYS_PTRACE)) { + rcu_read_unlock(); + return -EPERM; + } + rcu_read_unlock(); + smp_rmb(); + if (task->mm) + dumpable = get_dumpable(task->mm); + if (!dumpable && !capable(CAP_SYS_PTRACE)) + return -EPERM; + + return security_ptrace_access_check(task, mode); +} + +bool ptrace_may_access(struct task_struct *task, unsigned int mode) +{ + int err; + task_lock(task); + err = __ptrace_may_access(task, mode); + task_unlock(task); + return !err; +} + +int ptrace_attach(struct task_struct *task) +{ + int retval; + + audit_ptrace(task); + + retval = -EPERM; + if (unlikely(task->flags & PF_KTHREAD)) + goto out; + if (same_thread_group(task, current)) + goto out; + + /* + * Protect exec's credential calculations against our interference; + * interference; SUID, SGID and LSM creds get determined differently + * under ptrace. + */ + retval = -ERESTARTNOINTR; + if (mutex_lock_interruptible(&task->cred_guard_mutex)) + goto out; + + task_lock(task); + retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH); + task_unlock(task); + if (retval) + goto unlock_creds; + + write_lock_irq(&tasklist_lock); + retval = -EPERM; + if (unlikely(task->exit_state)) + goto unlock_tasklist; + if (task->ptrace) + goto unlock_tasklist; + + task->ptrace = PT_PTRACED; + if (capable(CAP_SYS_PTRACE)) + task->ptrace |= PT_PTRACE_CAP; + + __ptrace_link(task, current); + send_sig_info(SIGSTOP, SEND_SIG_FORCED, task); + + retval = 0; +unlock_tasklist: + write_unlock_irq(&tasklist_lock); +unlock_creds: + mutex_unlock(&task->cred_guard_mutex); +out: + return retval; +} + +/** + * ptrace_traceme -- helper for PTRACE_TRACEME + * + * Performs checks and sets PT_PTRACED. + * Should be used by all ptrace implementations for PTRACE_TRACEME. + */ +int ptrace_traceme(void) +{ + int ret = -EPERM; + + write_lock_irq(&tasklist_lock); + /* Are we already being traced? */ + if (!current->ptrace) { + ret = security_ptrace_traceme(current->parent); + /* + * Check PF_EXITING to ensure ->real_parent has not passed + * exit_ptrace(). Otherwise we don't report the error but + * pretend ->real_parent untraces us right after return. + */ + if (!ret && !(current->real_parent->flags & PF_EXITING)) { + current->ptrace = PT_PTRACED; + __ptrace_link(current, current->real_parent); + } + } + write_unlock_irq(&tasklist_lock); + + return ret; +} + +/* + * Called with irqs disabled, returns true if childs should reap themselves. + */ +static int ignoring_children(struct sighand_struct *sigh) +{ + int ret; + spin_lock(&sigh->siglock); + ret = (sigh->action[SIGCHLD-1].sa.sa_handler == SIG_IGN) || + (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT); + spin_unlock(&sigh->siglock); + return ret; +} + +/* + * Called with tasklist_lock held for writing. + * Unlink a traced task, and clean it up if it was a traced zombie. + * Return true if it needs to be reaped with release_task(). + * (We can't call release_task() here because we already hold tasklist_lock.) + * + * If it's a zombie, our attachedness prevented normal parent notification + * or self-reaping. Do notification now if it would have happened earlier. + * If it should reap itself, return true. + * + * If it's our own child, there is no notification to do. But if our normal + * children self-reap, then this child was prevented by ptrace and we must + * reap it now, in that case we must also wake up sub-threads sleeping in + * do_wait(). + */ +static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p) +{ + __ptrace_unlink(p); + + if (p->exit_state == EXIT_ZOMBIE) { + if (!task_detached(p) && thread_group_empty(p)) { + if (!same_thread_group(p->real_parent, tracer)) + do_notify_parent(p, p->exit_signal); + else if (ignoring_children(tracer->sighand)) { + __wake_up_parent(p, tracer); + p->exit_signal = -1; + } + } + if (task_detached(p)) { + /* Mark it as in the process of being reaped. */ + p->exit_state = EXIT_DEAD; + return true; + } + } + + return false; +} + +int ptrace_detach(struct task_struct *child, unsigned int data) +{ + bool dead = false; + + if (!valid_signal(data)) + return -EIO; + + /* Architecture-specific hardware disable .. */ + ptrace_disable(child); + clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); + + write_lock_irq(&tasklist_lock); + /* + * This child can be already killed. Make sure de_thread() or + * our sub-thread doing do_wait() didn't do release_task() yet. + */ + if (child->ptrace) { + child->exit_code = data; + dead = __ptrace_detach(current, child); + if (!child->exit_state) + wake_up_process(child); + } + write_unlock_irq(&tasklist_lock); + + if (unlikely(dead)) + release_task(child); + + return 0; +} + +/* + * Detach all tasks we were using ptrace on. + */ +void exit_ptrace(struct task_struct *tracer) +{ + struct task_struct *p, *n; + LIST_HEAD(ptrace_dead); + + write_lock_irq(&tasklist_lock); + list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) { + if (__ptrace_detach(tracer, p)) + list_add(&p->ptrace_entry, &ptrace_dead); + } + write_unlock_irq(&tasklist_lock); + + BUG_ON(!list_empty(&tracer->ptraced)); + + list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_entry) { + list_del_init(&p->ptrace_entry); + release_task(p); + } +} + +int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) +{ + int copied = 0; + + while (len > 0) { + char buf[128]; + int this_len, retval; + + this_len = (len > sizeof(buf)) ? sizeof(buf) : len; + retval = access_process_vm(tsk, src, buf, this_len, 0); + if (!retval) { + if (copied) + break; + return -EIO; + } + if (copy_to_user(dst, buf, retval)) + return -EFAULT; + copied += retval; + src += retval; + dst += retval; + len -= retval; + } + return copied; +} + +int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) +{ + int copied = 0; + + while (len > 0) { + char buf[128]; + int this_len, retval; + + this_len = (len > sizeof(buf)) ? sizeof(buf) : len; + if (copy_from_user(buf, src, this_len)) + return -EFAULT; + retval = access_process_vm(tsk, dst, buf, this_len, 1); + if (!retval) { + if (copied) + break; + return -EIO; + } + copied += retval; + src += retval; + dst += retval; + len -= retval; + } + return copied; +} + +static int ptrace_setoptions(struct task_struct *child, long data) +{ + child->ptrace &= ~PT_TRACE_MASK; + + if (data & PTRACE_O_TRACESYSGOOD) + child->ptrace |= PT_TRACESYSGOOD; + + if (data & PTRACE_O_TRACEFORK) + child->ptrace |= PT_TRACE_FORK; + + if (data & PTRACE_O_TRACEVFORK) + child->ptrace |= PT_TRACE_VFORK; + + if (data & PTRACE_O_TRACECLONE) + child->ptrace |= PT_TRACE_CLONE; + + if (data & PTRACE_O_TRACEEXEC) + child->ptrace |= PT_TRACE_EXEC; + + if (data & PTRACE_O_TRACEVFORKDONE) + child->ptrace |= PT_TRACE_VFORK_DONE; + + if (data & PTRACE_O_TRACEEXIT) + child->ptrace |= PT_TRACE_EXIT; + + return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; +} + +static int ptrace_getsiginfo(struct task_struct *child, siginfo_t *info) +{ + unsigned long flags; + int error = -ESRCH; + + if (lock_task_sighand(child, &flags)) { + error = -EINVAL; + if (likely(child->last_siginfo != NULL)) { + *info = *child->last_siginfo; + error = 0; + } + unlock_task_sighand(child, &flags); + } + return error; +} + +static int ptrace_setsiginfo(struct task_struct *child, const siginfo_t *info) +{ + unsigned long flags; + int error = -ESRCH; + + if (lock_task_sighand(child, &flags)) { + error = -EINVAL; + if (likely(child->last_siginfo != NULL)) { + *child->last_siginfo = *info; + error = 0; + } + unlock_task_sighand(child, &flags); + } + return error; +} + + +#ifdef PTRACE_SINGLESTEP +#define is_singlestep(request) ((request) == PTRACE_SINGLESTEP) +#else +#define is_singlestep(request) 0 +#endif + +#ifdef PTRACE_SINGLEBLOCK +#define is_singleblock(request) ((request) == PTRACE_SINGLEBLOCK) +#else +#define is_singleblock(request) 0 +#endif + +#ifdef PTRACE_SYSEMU +#define is_sysemu_singlestep(request) ((request) == PTRACE_SYSEMU_SINGLESTEP) +#else +#define is_sysemu_singlestep(request) 0 +#endif + +static int ptrace_resume(struct task_struct *child, long request, long data) +{ + if (!valid_signal(data)) + return -EIO; + + if (request == PTRACE_SYSCALL) + set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); + else + clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); + +#ifdef TIF_SYSCALL_EMU + if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP) + set_tsk_thread_flag(child, TIF_SYSCALL_EMU); + else + clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); +#endif + + if (is_singleblock(request)) { + if (unlikely(!arch_has_block_step())) + return -EIO; + user_enable_block_step(child); + } else if (is_singlestep(request) || is_sysemu_singlestep(request)) { + if (unlikely(!arch_has_single_step())) + return -EIO; + user_enable_single_step(child); + } else { + user_disable_single_step(child); + } + + child->exit_code = data; + wake_up_process(child); + + return 0; +} + +int ptrace_request(struct task_struct *child, long request, + long addr, long data) +{ + int ret = -EIO; + siginfo_t siginfo; + + switch (request) { + case PTRACE_PEEKTEXT: + case PTRACE_PEEKDATA: + return generic_ptrace_peekdata(child, addr, data); + case PTRACE_POKETEXT: + case PTRACE_POKEDATA: + return generic_ptrace_pokedata(child, addr, data); + +#ifdef PTRACE_OLDSETOPTIONS + case PTRACE_OLDSETOPTIONS: +#endif + case PTRACE_SETOPTIONS: + ret = ptrace_setoptions(child, data); + break; + case PTRACE_GETEVENTMSG: + ret = put_user(child->ptrace_message, (unsigned long __user *) data); + break; + + case PTRACE_GETSIGINFO: + ret = ptrace_getsiginfo(child, &siginfo); + if (!ret) + ret = copy_siginfo_to_user((siginfo_t __user *) data, + &siginfo); + break; + + case PTRACE_SETSIGINFO: + if (copy_from_user(&siginfo, (siginfo_t __user *) data, + sizeof siginfo)) + ret = -EFAULT; + else + ret = ptrace_setsiginfo(child, &siginfo); + break; + + case PTRACE_DETACH: /* detach a process that was attached. */ + ret = ptrace_detach(child, data); + break; + +#ifdef PTRACE_SINGLESTEP + case PTRACE_SINGLESTEP: +#endif +#ifdef PTRACE_SINGLEBLOCK + case PTRACE_SINGLEBLOCK: +#endif +#ifdef PTRACE_SYSEMU + case PTRACE_SYSEMU: + case PTRACE_SYSEMU_SINGLESTEP: +#endif + case PTRACE_SYSCALL: + case PTRACE_CONT: + return ptrace_resume(child, request, data); + + case PTRACE_KILL: + if (child->exit_state) /* already dead */ + return 0; + return ptrace_resume(child, request, SIGKILL); + + default: + break; + } + + return ret; +} + +static struct task_struct *ptrace_get_task_struct(pid_t pid) +{ + struct task_struct *child; + + rcu_read_lock(); + child = find_task_by_vpid(pid); + if (child) + get_task_struct(child); + rcu_read_unlock(); + + if (!child) + return ERR_PTR(-ESRCH); + return child; +} + +#ifndef arch_ptrace_attach +#define arch_ptrace_attach(child) do { } while (0) +#endif + +SYSCALL_DEFINE4(ptrace, long, request, long, pid, long, addr, long, data) +{ + struct task_struct *child; + long ret; + + /* + * This lock_kernel fixes a subtle race with suid exec + */ + lock_kernel(); + if (request == PTRACE_TRACEME) { + ret = ptrace_traceme(); + if (!ret) + arch_ptrace_attach(current); + goto out; + } + + child = ptrace_get_task_struct(pid); + if (IS_ERR(child)) { + ret = PTR_ERR(child); + goto out; + } + + if (request == PTRACE_ATTACH) { + ret = ptrace_attach(child); + /* + * Some architectures need to do book-keeping after + * a ptrace attach. + */ + if (!ret) + arch_ptrace_attach(child); + goto out_put_task_struct; + } + + ret = ptrace_check_attach(child, request == PTRACE_KILL); + if (ret < 0) + goto out_put_task_struct; + + ret = arch_ptrace(child, request, addr, data); + + out_put_task_struct: + put_task_struct(child); + out: + unlock_kernel(); + return ret; +} + +int generic_ptrace_peekdata(struct task_struct *tsk, long addr, long data) +{ + unsigned long tmp; + int copied; + + copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0); + if (copied != sizeof(tmp)) + return -EIO; + return put_user(tmp, (unsigned long __user *)data); +} + +int generic_ptrace_pokedata(struct task_struct *tsk, long addr, long data) +{ + int copied; + + copied = access_process_vm(tsk, addr, &data, sizeof(data), 1); + return (copied == sizeof(data)) ? 0 : -EIO; +} + +#if defined CONFIG_COMPAT +#include <linux/compat.h> + +int compat_ptrace_request(struct task_struct *child, compat_long_t request, + compat_ulong_t addr, compat_ulong_t data) +{ + compat_ulong_t __user *datap = compat_ptr(data); + compat_ulong_t word; + siginfo_t siginfo; + int ret; + + switch (request) { + case PTRACE_PEEKTEXT: + case PTRACE_PEEKDATA: + ret = access_process_vm(child, addr, &word, sizeof(word), 0); + if (ret != sizeof(word)) + ret = -EIO; + else + ret = put_user(word, datap); + break; + + case PTRACE_POKETEXT: + case PTRACE_POKEDATA: + ret = access_process_vm(child, addr, &data, sizeof(data), 1); + ret = (ret != sizeof(data) ? -EIO : 0); + break; + + case PTRACE_GETEVENTMSG: + ret = put_user((compat_ulong_t) child->ptrace_message, datap); + break; + + case PTRACE_GETSIGINFO: + ret = ptrace_getsiginfo(child, &siginfo); + if (!ret) + ret = copy_siginfo_to_user32( + (struct compat_siginfo __user *) datap, + &siginfo); + break; + + case PTRACE_SETSIGINFO: + memset(&siginfo, 0, sizeof siginfo); + if (copy_siginfo_from_user32( + &siginfo, (struct compat_siginfo __user *) datap)) + ret = -EFAULT; + else + ret = ptrace_setsiginfo(child, &siginfo); + break; + + default: + ret = ptrace_request(child, request, addr, data); + } + + return ret; +} + +asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid, + compat_long_t addr, compat_long_t data) +{ + struct task_struct *child; + long ret; + + /* + * This lock_kernel fixes a subtle race with suid exec + */ + lock_kernel(); + if (request == PTRACE_TRACEME) { + ret = ptrace_traceme(); + goto out; + } + + child = ptrace_get_task_struct(pid); + if (IS_ERR(child)) { + ret = PTR_ERR(child); + goto out; + } + + if (request == PTRACE_ATTACH) { + ret = ptrace_attach(child); + /* + * Some architectures need to do book-keeping after + * a ptrace attach. + */ + if (!ret) + arch_ptrace_attach(child); + goto out_put_task_struct; + } + + ret = ptrace_check_attach(child, request == PTRACE_KILL); + if (!ret) + ret = compat_arch_ptrace(child, request, addr, data); + + out_put_task_struct: + put_task_struct(child); + out: + unlock_kernel(); + return ret; +} +#endif /* CONFIG_COMPAT */