diff options
Diffstat (limited to 'kernel/ptrace.c')
| -rw-r--r-- | kernel/ptrace.c | 1456 |
1 files changed, 1456 insertions, 0 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c new file mode 100644 index 000000000..aab480e24 --- /dev/null +++ b/kernel/ptrace.c @@ -0,0 +1,1456 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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/export.h> +#include <linux/sched.h> +#include <linux/sched/mm.h> +#include <linux/sched/coredump.h> +#include <linux/sched/task.h> +#include <linux/errno.h> +#include <linux/mm.h> +#include <linux/highmem.h> +#include <linux/pagemap.h> +#include <linux/ptrace.h> +#include <linux/security.h> +#include <linux/signal.h> +#include <linux/uio.h> +#include <linux/audit.h> +#include <linux/pid_namespace.h> +#include <linux/syscalls.h> +#include <linux/uaccess.h> +#include <linux/regset.h> +#include <linux/hw_breakpoint.h> +#include <linux/cn_proc.h> +#include <linux/compat.h> +#include <linux/sched/signal.h> + +#include <asm/syscall.h> /* for syscall_get_* */ + +/* + * Access another process' address space via ptrace. + * Source/target buffer must be kernel space, + * Do not walk the page table directly, use get_user_pages + */ +int ptrace_access_vm(struct task_struct *tsk, unsigned long addr, + void *buf, int len, unsigned int gup_flags) +{ + struct mm_struct *mm; + int ret; + + mm = get_task_mm(tsk); + if (!mm) + return 0; + + if (!tsk->ptrace || + (current != tsk->parent) || + ((get_dumpable(mm) != SUID_DUMP_USER) && + !ptracer_capable(tsk, mm->user_ns))) { + mmput(mm); + return 0; + } + + ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags); + mmput(mm); + + return ret; +} + + +void __ptrace_link(struct task_struct *child, struct task_struct *new_parent, + const struct cred *ptracer_cred) +{ + BUG_ON(!list_empty(&child->ptrace_entry)); + list_add(&child->ptrace_entry, &new_parent->ptraced); + child->parent = new_parent; + child->ptracer_cred = get_cred(ptracer_cred); +} + +/* + * 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. + */ +static void ptrace_link(struct task_struct *child, struct task_struct *new_parent) +{ + __ptrace_link(child, new_parent, current_cred()); +} + +/** + * __ptrace_unlink - unlink ptracee and restore its execution state + * @child: ptracee to be unlinked + * + * Remove @child from the ptrace list, move it back to the original parent, + * and restore the execution state so that it conforms to the group stop + * state. + * + * Unlinking can happen via two paths - explicit PTRACE_DETACH or ptracer + * exiting. For PTRACE_DETACH, unless the ptracee has been killed between + * ptrace_check_attach() and here, it's guaranteed to be in TASK_TRACED. + * If the ptracer is exiting, the ptracee can be in any state. + * + * After detach, the ptracee should be in a state which conforms to the + * group stop. If the group is stopped or in the process of stopping, the + * ptracee should be put into TASK_STOPPED; otherwise, it should be woken + * up from TASK_TRACED. + * + * If the ptracee is in TASK_TRACED and needs to be moved to TASK_STOPPED, + * it goes through TRACED -> RUNNING -> STOPPED transition which is similar + * to but in the opposite direction of what happens while attaching to a + * stopped task. However, in this direction, the intermediate RUNNING + * state is not hidden even from the current ptracer and if it immediately + * re-attaches and performs a WNOHANG wait(2), it may fail. + * + * CONTEXT: + * write_lock_irq(tasklist_lock) + */ +void __ptrace_unlink(struct task_struct *child) +{ + const struct cred *old_cred; + BUG_ON(!child->ptrace); + + clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); +#ifdef TIF_SYSCALL_EMU + clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); +#endif + + child->parent = child->real_parent; + list_del_init(&child->ptrace_entry); + old_cred = child->ptracer_cred; + child->ptracer_cred = NULL; + put_cred(old_cred); + + spin_lock(&child->sighand->siglock); + child->ptrace = 0; + /* + * Clear all pending traps and TRAPPING. TRAPPING should be + * cleared regardless of JOBCTL_STOP_PENDING. Do it explicitly. + */ + task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK); + task_clear_jobctl_trapping(child); + + /* + * Reinstate JOBCTL_STOP_PENDING if group stop is in effect and + * @child isn't dead. + */ + if (!(child->flags & PF_EXITING) && + (child->signal->flags & SIGNAL_STOP_STOPPED || + child->signal->group_stop_count)) { + child->jobctl |= JOBCTL_STOP_PENDING; + + /* + * This is only possible if this thread was cloned by the + * traced task running in the stopped group, set the signal + * for the future reports. + * FIXME: we should change ptrace_init_task() to handle this + * case. + */ + if (!(child->jobctl & JOBCTL_STOP_SIGMASK)) + child->jobctl |= SIGSTOP; + } + + /* + * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick + * @child in the butt. Note that @resume should be used iff @child + * is in TASK_TRACED; otherwise, we might unduly disrupt + * TASK_KILLABLE sleeps. + */ + if (child->jobctl & JOBCTL_STOP_PENDING || task_is_traced(child)) + ptrace_signal_wake_up(child, true); + + spin_unlock(&child->sighand->siglock); +} + +static bool looks_like_a_spurious_pid(struct task_struct *task) +{ + if (task->exit_code != ((PTRACE_EVENT_EXEC << 8) | SIGTRAP)) + return false; + + if (task_pid_vnr(task) == task->ptrace_message) + return false; + /* + * The tracee changed its pid but the PTRACE_EVENT_EXEC event + * was not wait()'ed, most probably debugger targets the old + * leader which was destroyed in de_thread(). + */ + return true; +} + +/* Ensure that nothing can wake it up, even SIGKILL */ +static bool ptrace_freeze_traced(struct task_struct *task) +{ + bool ret = false; + + /* Lockless, nobody but us can set this flag */ + if (task->jobctl & JOBCTL_LISTENING) + return ret; + + spin_lock_irq(&task->sighand->siglock); + if (task_is_traced(task) && !looks_like_a_spurious_pid(task) && + !__fatal_signal_pending(task)) { + task->state = __TASK_TRACED; + ret = true; + } + spin_unlock_irq(&task->sighand->siglock); + + return ret; +} + +static void ptrace_unfreeze_traced(struct task_struct *task) +{ + if (task->state != __TASK_TRACED) + return; + + WARN_ON(!task->ptrace || task->parent != current); + + /* + * PTRACE_LISTEN can allow ptrace_trap_notify to wake us up remotely. + * Recheck state under the lock to close this race. + */ + spin_lock_irq(&task->sighand->siglock); + if (task->state == __TASK_TRACED) { + if (__fatal_signal_pending(task)) + wake_up_state(task, __TASK_TRACED); + else + task->state = TASK_TRACED; + } + spin_unlock_irq(&task->sighand->siglock); +} + +/** + * ptrace_check_attach - check whether ptracee is ready for ptrace operation + * @child: ptracee to check for + * @ignore_state: don't check whether @child is currently %TASK_TRACED + * + * Check whether @child is being ptraced by %current and ready for further + * ptrace operations. If @ignore_state is %false, @child also should be in + * %TASK_TRACED state and on return the child is guaranteed to be traced + * and not executing. If @ignore_state is %true, @child can be in any + * state. + * + * CONTEXT: + * Grabs and releases tasklist_lock and @child->sighand->siglock. + * + * RETURNS: + * 0 on success, -ESRCH if %child is not ready. + */ +static int ptrace_check_attach(struct task_struct *child, bool ignore_state) +{ + 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 && child->parent == current) { + WARN_ON(child->state == __TASK_TRACED); + /* + * child->sighand can't be NULL, release_task() + * does ptrace_unlink() before __exit_signal(). + */ + if (ignore_state || ptrace_freeze_traced(child)) + ret = 0; + } + read_unlock(&tasklist_lock); + + if (!ret && !ignore_state) { + if (!wait_task_inactive(child, __TASK_TRACED)) { + /* + * This can only happen if may_ptrace_stop() fails and + * ptrace_stop() changes ->state back to TASK_RUNNING, + * so we should not worry about leaking __TASK_TRACED. + */ + WARN_ON(child->state == __TASK_TRACED); + ret = -ESRCH; + } + } + + return ret; +} + +static bool ptrace_has_cap(struct user_namespace *ns, unsigned int mode) +{ + if (mode & PTRACE_MODE_NOAUDIT) + return ns_capable_noaudit(ns, CAP_SYS_PTRACE); + return ns_capable(ns, CAP_SYS_PTRACE); +} + +/* Returns 0 on success, -errno on denial. */ +static int __ptrace_may_access(struct task_struct *task, unsigned int mode) +{ + const struct cred *cred = current_cred(), *tcred; + struct mm_struct *mm; + kuid_t caller_uid; + kgid_t caller_gid; + + if (!(mode & PTRACE_MODE_FSCREDS) == !(mode & PTRACE_MODE_REALCREDS)) { + WARN(1, "denying ptrace access check without PTRACE_MODE_*CREDS\n"); + return -EPERM; + } + + /* 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. + */ + + /* Don't let security modules deny introspection */ + if (same_thread_group(task, current)) + return 0; + rcu_read_lock(); + if (mode & PTRACE_MODE_FSCREDS) { + caller_uid = cred->fsuid; + caller_gid = cred->fsgid; + } else { + /* + * Using the euid would make more sense here, but something + * in userland might rely on the old behavior, and this + * shouldn't be a security problem since + * PTRACE_MODE_REALCREDS implies that the caller explicitly + * used a syscall that requests access to another process + * (and not a filesystem syscall to procfs). + */ + caller_uid = cred->uid; + caller_gid = cred->gid; + } + tcred = __task_cred(task); + if (uid_eq(caller_uid, tcred->euid) && + uid_eq(caller_uid, tcred->suid) && + uid_eq(caller_uid, tcred->uid) && + gid_eq(caller_gid, tcred->egid) && + gid_eq(caller_gid, tcred->sgid) && + gid_eq(caller_gid, tcred->gid)) + goto ok; + if (ptrace_has_cap(tcred->user_ns, mode)) + goto ok; + rcu_read_unlock(); + return -EPERM; +ok: + rcu_read_unlock(); + /* + * If a task drops privileges and becomes nondumpable (through a syscall + * like setresuid()) while we are trying to access it, we must ensure + * that the dumpability is read after the credentials; otherwise, + * we may be able to attach to a task that we shouldn't be able to + * attach to (as if the task had dropped privileges without becoming + * nondumpable). + * Pairs with a write barrier in commit_creds(). + */ + smp_rmb(); + mm = task->mm; + if (mm && + ((get_dumpable(mm) != SUID_DUMP_USER) && + !ptrace_has_cap(mm->user_ns, mode))) + 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; +} + +static int check_ptrace_options(unsigned long data) +{ + if (data & ~(unsigned long)PTRACE_O_MASK) + return -EINVAL; + + if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) { + if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) || + !IS_ENABLED(CONFIG_SECCOMP)) + return -EINVAL; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (seccomp_mode(¤t->seccomp) != SECCOMP_MODE_DISABLED || + current->ptrace & PT_SUSPEND_SECCOMP) + return -EPERM; + } + return 0; +} + +static int ptrace_attach(struct task_struct *task, long request, + unsigned long addr, + unsigned long flags) +{ + bool seize = (request == PTRACE_SEIZE); + int retval; + + retval = -EIO; + if (seize) { + if (addr != 0) + goto out; + /* + * This duplicates the check in check_ptrace_options() because + * ptrace_attach() and ptrace_setoptions() have historically + * used different error codes for unknown ptrace options. + */ + if (flags & ~(unsigned long)PTRACE_O_MASK) + goto out; + retval = check_ptrace_options(flags); + if (retval) + return retval; + flags = PT_PTRACED | PT_SEIZED | (flags << PT_OPT_FLAG_SHIFT); + } else { + flags = PT_PTRACED; + } + + 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; + * SUID, SGID and LSM creds get determined differently + * under ptrace. + */ + retval = -ERESTARTNOINTR; + if (mutex_lock_interruptible(&task->signal->cred_guard_mutex)) + goto out; + + task_lock(task); + retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH_REALCREDS); + 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; + + if (seize) + flags |= PT_SEIZED; + task->ptrace = flags; + + ptrace_link(task, current); + + /* SEIZE doesn't trap tracee on attach */ + if (!seize) + send_sig_info(SIGSTOP, SEND_SIG_PRIV, task); + + spin_lock(&task->sighand->siglock); + + /* + * If the task is already STOPPED, set JOBCTL_TRAP_STOP and + * TRAPPING, and kick it so that it transits to TRACED. TRAPPING + * will be cleared if the child completes the transition or any + * event which clears the group stop states happens. We'll wait + * for the transition to complete before returning from this + * function. + * + * This hides STOPPED -> RUNNING -> TRACED transition from the + * attaching thread but a different thread in the same group can + * still observe the transient RUNNING state. IOW, if another + * thread's WNOHANG wait(2) on the stopped tracee races against + * ATTACH, the wait(2) may fail due to the transient RUNNING. + * + * The following task_is_stopped() test is safe as both transitions + * in and out of STOPPED are protected by siglock. + */ + if (task_is_stopped(task) && + task_set_jobctl_pending(task, JOBCTL_TRAP_STOP | JOBCTL_TRAPPING)) + signal_wake_up_state(task, __TASK_STOPPED); + + spin_unlock(&task->sighand->siglock); + + retval = 0; +unlock_tasklist: + write_unlock_irq(&tasklist_lock); +unlock_creds: + mutex_unlock(&task->signal->cred_guard_mutex); +out: + if (!retval) { + /* + * We do not bother to change retval or clear JOBCTL_TRAPPING + * if wait_on_bit() was interrupted by SIGKILL. The tracer will + * not return to user-mode, it will exit and clear this bit in + * __ptrace_unlink() if it wasn't already cleared by the tracee; + * and until then nobody can ptrace this task. + */ + wait_on_bit(&task->jobctl, JOBCTL_TRAPPING_BIT, TASK_KILLABLE); + proc_ptrace_connector(task, PTRACE_ATTACH); + } + + return retval; +} + +/** + * ptrace_traceme -- helper for PTRACE_TRACEME + * + * Performs checks and sets PT_PTRACED. + * Should be used by all ptrace implementations for PTRACE_TRACEME. + */ +static 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) +{ + bool dead; + + __ptrace_unlink(p); + + if (p->exit_state != EXIT_ZOMBIE) + return false; + + dead = !thread_group_leader(p); + + if (!dead && thread_group_empty(p)) { + if (!same_thread_group(p->real_parent, tracer)) + dead = do_notify_parent(p, p->exit_signal); + else if (ignoring_children(tracer->sighand)) { + __wake_up_parent(p, tracer); + dead = true; + } + } + /* Mark it as in the process of being reaped. */ + if (dead) + p->exit_state = EXIT_DEAD; + return dead; +} + +static int ptrace_detach(struct task_struct *child, unsigned int data) +{ + if (!valid_signal(data)) + return -EIO; + + /* Architecture-specific hardware disable .. */ + ptrace_disable(child); + + write_lock_irq(&tasklist_lock); + /* + * We rely on ptrace_freeze_traced(). It can't be killed and + * untraced by another thread, it can't be a zombie. + */ + WARN_ON(!child->ptrace || child->exit_state); + /* + * tasklist_lock avoids the race with wait_task_stopped(), see + * the comment in ptrace_resume(). + */ + child->exit_code = data; + __ptrace_detach(current, child); + write_unlock_irq(&tasklist_lock); + + proc_ptrace_connector(child, PTRACE_DETACH); + + return 0; +} + +/* + * Detach all tasks we were using ptrace on. Called with tasklist held + * for writing. + */ +void exit_ptrace(struct task_struct *tracer, struct list_head *dead) +{ + struct task_struct *p, *n; + + list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) { + if (unlikely(p->ptrace & PT_EXITKILL)) + send_sig_info(SIGKILL, SEND_SIG_PRIV, p); + + if (__ptrace_detach(tracer, p)) + list_add(&p->ptrace_entry, dead); + } +} + +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 = ptrace_access_vm(tsk, src, buf, this_len, FOLL_FORCE); + + 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 = ptrace_access_vm(tsk, dst, buf, this_len, + FOLL_FORCE | FOLL_WRITE); + 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, unsigned long data) +{ + unsigned flags; + int ret; + + ret = check_ptrace_options(data); + if (ret) + return ret; + + /* Avoid intermediate state when all opts are cleared */ + flags = child->ptrace; + flags &= ~(PTRACE_O_MASK << PT_OPT_FLAG_SHIFT); + flags |= (data << PT_OPT_FLAG_SHIFT); + child->ptrace = flags; + + return 0; +} + +static int ptrace_getsiginfo(struct task_struct *child, kernel_siginfo_t *info) +{ + unsigned long flags; + int error = -ESRCH; + + if (lock_task_sighand(child, &flags)) { + error = -EINVAL; + if (likely(child->last_siginfo != NULL)) { + copy_siginfo(info, child->last_siginfo); + error = 0; + } + unlock_task_sighand(child, &flags); + } + return error; +} + +static int ptrace_setsiginfo(struct task_struct *child, const kernel_siginfo_t *info) +{ + unsigned long flags; + int error = -ESRCH; + + if (lock_task_sighand(child, &flags)) { + error = -EINVAL; + if (likely(child->last_siginfo != NULL)) { + copy_siginfo(child->last_siginfo, info); + error = 0; + } + unlock_task_sighand(child, &flags); + } + return error; +} + +static int ptrace_peek_siginfo(struct task_struct *child, + unsigned long addr, + unsigned long data) +{ + struct ptrace_peeksiginfo_args arg; + struct sigpending *pending; + struct sigqueue *q; + int ret, i; + + ret = copy_from_user(&arg, (void __user *) addr, + sizeof(struct ptrace_peeksiginfo_args)); + if (ret) + return -EFAULT; + + if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED) + return -EINVAL; /* unknown flags */ + + if (arg.nr < 0) + return -EINVAL; + + /* Ensure arg.off fits in an unsigned long */ + if (arg.off > ULONG_MAX) + return 0; + + if (arg.flags & PTRACE_PEEKSIGINFO_SHARED) + pending = &child->signal->shared_pending; + else + pending = &child->pending; + + for (i = 0; i < arg.nr; ) { + kernel_siginfo_t info; + unsigned long off = arg.off + i; + bool found = false; + + spin_lock_irq(&child->sighand->siglock); + list_for_each_entry(q, &pending->list, list) { + if (!off--) { + found = true; + copy_siginfo(&info, &q->info); + break; + } + } + spin_unlock_irq(&child->sighand->siglock); + + if (!found) /* beyond the end of the list */ + break; + +#ifdef CONFIG_COMPAT + if (unlikely(in_compat_syscall())) { + compat_siginfo_t __user *uinfo = compat_ptr(data); + + if (copy_siginfo_to_user32(uinfo, &info)) { + ret = -EFAULT; + break; + } + + } else +#endif + { + siginfo_t __user *uinfo = (siginfo_t __user *) data; + + if (copy_siginfo_to_user(uinfo, &info)) { + ret = -EFAULT; + break; + } + } + + data += sizeof(siginfo_t); + i++; + + if (signal_pending(current)) + break; + + cond_resched(); + } + + if (i > 0) + return i; + + return ret; +} + +#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, + unsigned long data) +{ + bool need_siglock; + + 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); + } + + /* + * Change ->exit_code and ->state under siglock to avoid the race + * with wait_task_stopped() in between; a non-zero ->exit_code will + * wrongly look like another report from tracee. + * + * Note that we need siglock even if ->exit_code == data and/or this + * status was not reported yet, the new status must not be cleared by + * wait_task_stopped() after resume. + * + * If data == 0 we do not care if wait_task_stopped() reports the old + * status and clears the code too; this can't race with the tracee, it + * takes siglock after resume. + */ + need_siglock = data && !thread_group_empty(current); + if (need_siglock) + spin_lock_irq(&child->sighand->siglock); + child->exit_code = data; + wake_up_state(child, __TASK_TRACED); + if (need_siglock) + spin_unlock_irq(&child->sighand->siglock); + + return 0; +} + +#ifdef CONFIG_HAVE_ARCH_TRACEHOOK + +static const struct user_regset * +find_regset(const struct user_regset_view *view, unsigned int type) +{ + const struct user_regset *regset; + int n; + + for (n = 0; n < view->n; ++n) { + regset = view->regsets + n; + if (regset->core_note_type == type) + return regset; + } + + return NULL; +} + +static int ptrace_regset(struct task_struct *task, int req, unsigned int type, + struct iovec *kiov) +{ + const struct user_regset_view *view = task_user_regset_view(task); + const struct user_regset *regset = find_regset(view, type); + int regset_no; + + if (!regset || (kiov->iov_len % regset->size) != 0) + return -EINVAL; + + regset_no = regset - view->regsets; + kiov->iov_len = min(kiov->iov_len, + (__kernel_size_t) (regset->n * regset->size)); + + if (req == PTRACE_GETREGSET) + return copy_regset_to_user(task, view, regset_no, 0, + kiov->iov_len, kiov->iov_base); + else + return copy_regset_from_user(task, view, regset_no, 0, + kiov->iov_len, kiov->iov_base); +} + +/* + * This is declared in linux/regset.h and defined in machine-dependent + * code. We put the export here, near the primary machine-neutral use, + * to ensure no machine forgets it. + */ +EXPORT_SYMBOL_GPL(task_user_regset_view); + +static unsigned long +ptrace_get_syscall_info_entry(struct task_struct *child, struct pt_regs *regs, + struct ptrace_syscall_info *info) +{ + unsigned long args[ARRAY_SIZE(info->entry.args)]; + int i; + + info->op = PTRACE_SYSCALL_INFO_ENTRY; + info->entry.nr = syscall_get_nr(child, regs); + syscall_get_arguments(child, regs, args); + for (i = 0; i < ARRAY_SIZE(args); i++) + info->entry.args[i] = args[i]; + + /* args is the last field in struct ptrace_syscall_info.entry */ + return offsetofend(struct ptrace_syscall_info, entry.args); +} + +static unsigned long +ptrace_get_syscall_info_seccomp(struct task_struct *child, struct pt_regs *regs, + struct ptrace_syscall_info *info) +{ + /* + * As struct ptrace_syscall_info.entry is currently a subset + * of struct ptrace_syscall_info.seccomp, it makes sense to + * initialize that subset using ptrace_get_syscall_info_entry(). + * This can be reconsidered in the future if these structures + * diverge significantly enough. + */ + ptrace_get_syscall_info_entry(child, regs, info); + info->op = PTRACE_SYSCALL_INFO_SECCOMP; + info->seccomp.ret_data = child->ptrace_message; + + /* ret_data is the last field in struct ptrace_syscall_info.seccomp */ + return offsetofend(struct ptrace_syscall_info, seccomp.ret_data); +} + +static unsigned long +ptrace_get_syscall_info_exit(struct task_struct *child, struct pt_regs *regs, + struct ptrace_syscall_info *info) +{ + info->op = PTRACE_SYSCALL_INFO_EXIT; + info->exit.rval = syscall_get_error(child, regs); + info->exit.is_error = !!info->exit.rval; + if (!info->exit.is_error) + info->exit.rval = syscall_get_return_value(child, regs); + + /* is_error is the last field in struct ptrace_syscall_info.exit */ + return offsetofend(struct ptrace_syscall_info, exit.is_error); +} + +static int +ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size, + void __user *datavp) +{ + struct pt_regs *regs = task_pt_regs(child); + struct ptrace_syscall_info info = { + .op = PTRACE_SYSCALL_INFO_NONE, + .arch = syscall_get_arch(child), + .instruction_pointer = instruction_pointer(regs), + .stack_pointer = user_stack_pointer(regs), + }; + unsigned long actual_size = offsetof(struct ptrace_syscall_info, entry); + unsigned long write_size; + + /* + * This does not need lock_task_sighand() to access + * child->last_siginfo because ptrace_freeze_traced() + * called earlier by ptrace_check_attach() ensures that + * the tracee cannot go away and clear its last_siginfo. + */ + switch (child->last_siginfo ? child->last_siginfo->si_code : 0) { + case SIGTRAP | 0x80: + switch (child->ptrace_message) { + case PTRACE_EVENTMSG_SYSCALL_ENTRY: + actual_size = ptrace_get_syscall_info_entry(child, regs, + &info); + break; + case PTRACE_EVENTMSG_SYSCALL_EXIT: + actual_size = ptrace_get_syscall_info_exit(child, regs, + &info); + break; + } + break; + case SIGTRAP | (PTRACE_EVENT_SECCOMP << 8): + actual_size = ptrace_get_syscall_info_seccomp(child, regs, + &info); + break; + } + + write_size = min(actual_size, user_size); + return copy_to_user(datavp, &info, write_size) ? -EFAULT : actual_size; +} +#endif /* CONFIG_HAVE_ARCH_TRACEHOOK */ + +int ptrace_request(struct task_struct *child, long request, + unsigned long addr, unsigned long data) +{ + bool seized = child->ptrace & PT_SEIZED; + int ret = -EIO; + kernel_siginfo_t siginfo, *si; + void __user *datavp = (void __user *) data; + unsigned long __user *datalp = datavp; + unsigned long flags; + + 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, datalp); + break; + + case PTRACE_PEEKSIGINFO: + ret = ptrace_peek_siginfo(child, addr, data); + break; + + case PTRACE_GETSIGINFO: + ret = ptrace_getsiginfo(child, &siginfo); + if (!ret) + ret = copy_siginfo_to_user(datavp, &siginfo); + break; + + case PTRACE_SETSIGINFO: + ret = copy_siginfo_from_user(&siginfo, datavp); + if (!ret) + ret = ptrace_setsiginfo(child, &siginfo); + break; + + case PTRACE_GETSIGMASK: { + sigset_t *mask; + + if (addr != sizeof(sigset_t)) { + ret = -EINVAL; + break; + } + + if (test_tsk_restore_sigmask(child)) + mask = &child->saved_sigmask; + else + mask = &child->blocked; + + if (copy_to_user(datavp, mask, sizeof(sigset_t))) + ret = -EFAULT; + else + ret = 0; + + break; + } + + case PTRACE_SETSIGMASK: { + sigset_t new_set; + + if (addr != sizeof(sigset_t)) { + ret = -EINVAL; + break; + } + + if (copy_from_user(&new_set, datavp, sizeof(sigset_t))) { + ret = -EFAULT; + break; + } + + sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP)); + + /* + * Every thread does recalc_sigpending() after resume, so + * retarget_shared_pending() and recalc_sigpending() are not + * called here. + */ + spin_lock_irq(&child->sighand->siglock); + child->blocked = new_set; + spin_unlock_irq(&child->sighand->siglock); + + clear_tsk_restore_sigmask(child); + + ret = 0; + break; + } + + case PTRACE_INTERRUPT: + /* + * Stop tracee without any side-effect on signal or job + * control. At least one trap is guaranteed to happen + * after this request. If @child is already trapped, the + * current trap is not disturbed and another trap will + * happen after the current trap is ended with PTRACE_CONT. + * + * The actual trap might not be PTRACE_EVENT_STOP trap but + * the pending condition is cleared regardless. + */ + if (unlikely(!seized || !lock_task_sighand(child, &flags))) + break; + + /* + * INTERRUPT doesn't disturb existing trap sans one + * exception. If ptracer issued LISTEN for the current + * STOP, this INTERRUPT should clear LISTEN and re-trap + * tracee into STOP. + */ + if (likely(task_set_jobctl_pending(child, JOBCTL_TRAP_STOP))) + ptrace_signal_wake_up(child, child->jobctl & JOBCTL_LISTENING); + + unlock_task_sighand(child, &flags); + ret = 0; + break; + + case PTRACE_LISTEN: + /* + * Listen for events. Tracee must be in STOP. It's not + * resumed per-se but is not considered to be in TRACED by + * wait(2) or ptrace(2). If an async event (e.g. group + * stop state change) happens, tracee will enter STOP trap + * again. Alternatively, ptracer can issue INTERRUPT to + * finish listening and re-trap tracee into STOP. + */ + if (unlikely(!seized || !lock_task_sighand(child, &flags))) + break; + + si = child->last_siginfo; + if (likely(si && (si->si_code >> 8) == PTRACE_EVENT_STOP)) { + child->jobctl |= JOBCTL_LISTENING; + /* + * If NOTIFY is set, it means event happened between + * start of this trap and now. Trigger re-trap. + */ + if (child->jobctl & JOBCTL_TRAP_NOTIFY) + ptrace_signal_wake_up(child, true); + ret = 0; + } + unlock_task_sighand(child, &flags); + break; + + case PTRACE_DETACH: /* detach a process that was attached. */ + ret = ptrace_detach(child, data); + break; + +#ifdef CONFIG_BINFMT_ELF_FDPIC + case PTRACE_GETFDPIC: { + struct mm_struct *mm = get_task_mm(child); + unsigned long tmp = 0; + + ret = -ESRCH; + if (!mm) + break; + + switch (addr) { + case PTRACE_GETFDPIC_EXEC: + tmp = mm->context.exec_fdpic_loadmap; + break; + case PTRACE_GETFDPIC_INTERP: + tmp = mm->context.interp_fdpic_loadmap; + break; + default: + break; + } + mmput(mm); + + ret = put_user(tmp, datalp); + break; + } +#endif + +#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: + send_sig_info(SIGKILL, SEND_SIG_NOINFO, child); + return 0; + +#ifdef CONFIG_HAVE_ARCH_TRACEHOOK + case PTRACE_GETREGSET: + case PTRACE_SETREGSET: { + struct iovec kiov; + struct iovec __user *uiov = datavp; + + if (!access_ok(uiov, sizeof(*uiov))) + return -EFAULT; + + if (__get_user(kiov.iov_base, &uiov->iov_base) || + __get_user(kiov.iov_len, &uiov->iov_len)) + return -EFAULT; + + ret = ptrace_regset(child, request, addr, &kiov); + if (!ret) + ret = __put_user(kiov.iov_len, &uiov->iov_len); + break; + } + + case PTRACE_GET_SYSCALL_INFO: + ret = ptrace_get_syscall_info(child, addr, datavp); + break; +#endif + + case PTRACE_SECCOMP_GET_FILTER: + ret = seccomp_get_filter(child, addr, datavp); + break; + + case PTRACE_SECCOMP_GET_METADATA: + ret = seccomp_get_metadata(child, addr, datavp); + break; + + default: + break; + } + + return ret; +} + +#ifndef arch_ptrace_attach +#define arch_ptrace_attach(child) do { } while (0) +#endif + +SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr, + unsigned long, data) +{ + struct task_struct *child; + long ret; + + if (request == PTRACE_TRACEME) { + ret = ptrace_traceme(); + if (!ret) + arch_ptrace_attach(current); + goto out; + } + + child = find_get_task_by_vpid(pid); + if (!child) { + ret = -ESRCH; + goto out; + } + + if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) { + ret = ptrace_attach(child, request, addr, data); + /* + * 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 || + request == PTRACE_INTERRUPT); + if (ret < 0) + goto out_put_task_struct; + + ret = arch_ptrace(child, request, addr, data); + if (ret || request != PTRACE_DETACH) + ptrace_unfreeze_traced(child); + + out_put_task_struct: + put_task_struct(child); + out: + return ret; +} + +int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr, + unsigned long data) +{ + unsigned long tmp; + int copied; + + copied = ptrace_access_vm(tsk, addr, &tmp, sizeof(tmp), FOLL_FORCE); + if (copied != sizeof(tmp)) + return -EIO; + return put_user(tmp, (unsigned long __user *)data); +} + +int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr, + unsigned long data) +{ + int copied; + + copied = ptrace_access_vm(tsk, addr, &data, sizeof(data), + FOLL_FORCE | FOLL_WRITE); + return (copied == sizeof(data)) ? 0 : -EIO; +} + +#if defined CONFIG_COMPAT + +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; + kernel_siginfo_t siginfo; + int ret; + + switch (request) { + case PTRACE_PEEKTEXT: + case PTRACE_PEEKDATA: + ret = ptrace_access_vm(child, addr, &word, sizeof(word), + FOLL_FORCE); + if (ret != sizeof(word)) + ret = -EIO; + else + ret = put_user(word, datap); + break; + + case PTRACE_POKETEXT: + case PTRACE_POKEDATA: + ret = ptrace_access_vm(child, addr, &data, sizeof(data), + FOLL_FORCE | FOLL_WRITE); + 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: + ret = copy_siginfo_from_user32( + &siginfo, (struct compat_siginfo __user *) datap); + if (!ret) + ret = ptrace_setsiginfo(child, &siginfo); + break; +#ifdef CONFIG_HAVE_ARCH_TRACEHOOK + case PTRACE_GETREGSET: + case PTRACE_SETREGSET: + { + struct iovec kiov; + struct compat_iovec __user *uiov = + (struct compat_iovec __user *) datap; + compat_uptr_t ptr; + compat_size_t len; + + if (!access_ok(uiov, sizeof(*uiov))) + return -EFAULT; + + if (__get_user(ptr, &uiov->iov_base) || + __get_user(len, &uiov->iov_len)) + return -EFAULT; + + kiov.iov_base = compat_ptr(ptr); + kiov.iov_len = len; + + ret = ptrace_regset(child, request, addr, &kiov); + if (!ret) + ret = __put_user(kiov.iov_len, &uiov->iov_len); + break; + } +#endif + + default: + ret = ptrace_request(child, request, addr, data); + } + + return ret; +} + +COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid, + compat_long_t, addr, compat_long_t, data) +{ + struct task_struct *child; + long ret; + + if (request == PTRACE_TRACEME) { + ret = ptrace_traceme(); + goto out; + } + + child = find_get_task_by_vpid(pid); + if (!child) { + ret = -ESRCH; + goto out; + } + + if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) { + ret = ptrace_attach(child, request, addr, data); + /* + * 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 || + request == PTRACE_INTERRUPT); + if (!ret) { + ret = compat_arch_ptrace(child, request, addr, data); + if (ret || request != PTRACE_DETACH) + ptrace_unfreeze_traced(child); + } + + out_put_task_struct: + put_task_struct(child); + out: + return ret; +} +#endif /* CONFIG_COMPAT */ |