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Message-ID: <20091124200216.GA5825@redhat.com>
Date: Tue, 24 Nov 2009 21:02:16 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Alexey Dobriyan <adobriyan@...il.com>,
Ananth Mavinakayanahalli <ananth@...ibm.com>,
Christoph Hellwig <hch@...radead.org>,
"Frank Ch. Eigler" <fche@...hat.com>, Ingo Molnar <mingo@...e.hu>,
Peter Zijlstra <peterz@...radead.org>,
Roland McGrath <roland@...hat.com>
Cc: linux-kernel@...r.kernel.org, utrace-devel@...hat.com
Subject: [RFC,PATCH 13/14] implement utrace-ptrace
The patch adds the new file, kernel/ptrace-utrace.c, which contains
the new implementation of ptrace over utrace.
This file is not compiled until we have CONFIG_UTRACE option, will be
added by the next "utrace core" patch.
It's supposed to be an invisible implementation change, nothing should
change to userland when CONFIG_UTRACE is enabled.
Signed-off-by: Roland McGrath <roland@...hat.com>
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
include/linux/ptrace.h | 2
kernel/Makefile | 1
kernel/ptrace.c | 2
kernel/ptrace-utrace.c | 1115 +++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 1119 insertions(+), 1 deletion(-)
--- V1/include/linux/ptrace.h~13_UTRACE_PTRACE 2009-11-24 20:30:16.000000000 +0100
+++ V1/include/linux/ptrace.h 2009-11-24 20:30:17.000000000 +0100
@@ -79,7 +79,7 @@
#include <linux/compiler.h> /* For unlikely. */
#include <linux/sched.h> /* For struct task_struct. */
-
+extern void ptrace_notify_stop(struct task_struct *tracee);
extern long arch_ptrace(struct task_struct *child, long request, long addr, long data);
extern int ptrace_traceme(void);
extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
--- V1/kernel/Makefile~13_UTRACE_PTRACE 2009-11-24 20:27:23.000000000 +0100
+++ V1/kernel/Makefile 2009-11-24 20:30:17.000000000 +0100
@@ -68,6 +68,7 @@ obj-$(CONFIG_IKCONFIG) += configs.o
obj-$(CONFIG_RESOURCE_COUNTERS) += res_counter.o
obj-$(CONFIG_STOP_MACHINE) += stop_machine.o
obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
+obj-$(CONFIG_UTRACE) += ptrace-utrace.o
obj-$(CONFIG_AUDIT) += audit.o auditfilter.o audit_watch.o
obj-$(CONFIG_AUDITSYSCALL) += auditsc.o
obj-$(CONFIG_GCOV_KERNEL) += gcov/
--- V1/kernel/ptrace.c~13_UTRACE_PTRACE 2009-11-24 20:30:16.000000000 +0100
+++ V1/kernel/ptrace.c 2009-11-24 20:30:17.000000000 +0100
@@ -302,6 +302,7 @@ asmlinkage long compat_sys_ptrace(compat
}
#endif /* CONFIG_COMPAT */
+#ifndef CONFIG_UTRACE
/*
* ptrace a task: make the debugger its new parent and
* move it to the ptrace list.
@@ -762,3 +763,4 @@ int compat_ptrace_request(struct task_st
return ret;
}
#endif /* CONFIG_COMPAT */
+#endif /* CONFIG_UTRACE */
--- /dev/null 2009-11-24 16:51:11.614043008 +0100
+++ V1/kernel/ptrace-utrace.c 2009-11-24 20:30:17.000000000 +0100
@@ -0,0 +1,1115 @@
+/*
+ * 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/utrace.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;
+}
+
+/*
+ * 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);
+}
+
+struct ptrace_context {
+ int options;
+
+ int signr;
+ siginfo_t *siginfo;
+
+ int stop_code;
+ unsigned long eventmsg;
+
+ enum utrace_resume_action resume;
+};
+
+#define PT_UTRACED 0x00001000
+
+#define PTRACE_O_SYSEMU 0x100
+
+#define PTRACE_EVENT_SYSCALL (1 << 16)
+#define PTRACE_EVENT_SIGTRAP (2 << 16)
+#define PTRACE_EVENT_SIGNAL (3 << 16)
+/* events visible to user-space */
+#define PTRACE_EVENT_MASK 0xFFFF
+
+static inline bool ptrace_event_pending(struct ptrace_context *ctx)
+{
+ return ctx->stop_code != 0;
+}
+
+static inline int get_stop_event(struct ptrace_context *ctx)
+{
+ return ctx->stop_code >> 8;
+}
+
+static inline void set_stop_code(struct ptrace_context *ctx, int event)
+{
+ ctx->stop_code = (event << 8) | SIGTRAP;
+}
+
+static inline struct ptrace_context *
+ptrace_context(struct utrace_engine *engine)
+{
+ return engine->data;
+}
+
+static const struct utrace_engine_ops ptrace_utrace_ops; /* forward decl */
+
+static struct utrace_engine *ptrace_lookup_engine(struct task_struct *tracee)
+{
+ return utrace_attach_task(tracee, UTRACE_ATTACH_MATCH_OPS,
+ &ptrace_utrace_ops, NULL);
+}
+
+static struct utrace_engine *
+ptrace_reuse_engine(struct task_struct *tracee)
+{
+ struct utrace_engine *engine;
+ struct ptrace_context *ctx;
+ int err = -EPERM;
+
+ engine = ptrace_lookup_engine(tracee);
+ if (IS_ERR(engine))
+ return engine;
+
+ ctx = ptrace_context(engine);
+ if (unlikely(ctx->resume == UTRACE_DETACH)) {
+ /*
+ * Try to reuse this self-detaching engine.
+ * The only caller which can hit this case is ptrace_attach(),
+ * it holds ->cred_guard_mutex.
+ */
+ ctx->options = 0;
+ ctx->eventmsg = 0;
+
+ /* make sure we don't get unwanted reports */
+ err = utrace_set_events(tracee, engine, UTRACE_EVENT(QUIESCE));
+ if (!err || err == -EINPROGRESS) {
+ ctx->resume = UTRACE_RESUME;
+ /* synchronize with ptrace_report_signal() */
+ err = utrace_barrier(tracee, engine);
+ }
+ WARN_ON(!err != (engine->ops == &ptrace_utrace_ops));
+
+ if (!err)
+ return engine;
+ }
+
+ utrace_engine_put(engine);
+ return ERR_PTR(err);
+}
+
+static struct utrace_engine *
+ptrace_attach_engine(struct task_struct *tracee)
+{
+ struct utrace_engine *engine;
+ struct ptrace_context *ctx;
+
+ if (unlikely(task_utrace_flags(tracee))) {
+ engine = ptrace_reuse_engine(tracee);
+ if (!IS_ERR(engine) || IS_ERR(engine) == -EPERM)
+ return engine;
+ }
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (unlikely(!ctx))
+ return ERR_PTR(-ENOMEM);
+
+ ctx->resume = UTRACE_RESUME;
+
+ engine = utrace_attach_task(tracee, UTRACE_ATTACH_CREATE |
+ UTRACE_ATTACH_EXCLUSIVE |
+ UTRACE_ATTACH_MATCH_OPS,
+ &ptrace_utrace_ops, ctx);
+ if (unlikely(IS_ERR(engine))) {
+ if (engine != ERR_PTR(-ESRCH) &&
+ engine != ERR_PTR(-ERESTARTNOINTR))
+ engine = ERR_PTR(-EPERM);
+ kfree(ctx);
+ }
+
+ return engine;
+}
+
+static inline int ptrace_set_events(struct task_struct *target,
+ struct utrace_engine *engine,
+ unsigned long options)
+{
+ struct ptrace_context *ctx = ptrace_context(engine);
+ /*
+ * We need QUIESCE for resume handling, CLONE to check
+ * for CLONE_PTRACE, other events are always reported.
+ */
+ unsigned long events = UTRACE_EVENT(QUIESCE) | UTRACE_EVENT(CLONE) |
+ UTRACE_EVENT(EXEC) | UTRACE_EVENT_SIGNAL_ALL;
+
+ ctx->options = options;
+ if (options & PTRACE_O_TRACEEXIT)
+ events |= UTRACE_EVENT(EXIT);
+
+ return utrace_set_events(target, engine, events);
+}
+
+/*
+ * Attach a utrace engine for ptrace and set up its event mask.
+ * Returns error code or 0 on success.
+ */
+static int ptrace_attach_task(struct task_struct *tracee, int options)
+{
+ struct utrace_engine *engine;
+ int err;
+
+ engine = ptrace_attach_engine(tracee);
+ if (IS_ERR(engine))
+ return PTR_ERR(engine);
+ /*
+ * It can fail only if the tracee is dead, the caller
+ * must notice this before setting PT_UTRACED.
+ */
+ err = ptrace_set_events(tracee, engine, options);
+ WARN_ON(err && !tracee->exit_state);
+ utrace_engine_put(engine);
+ return 0;
+}
+
+static void ptrace_wake_up(struct task_struct *tracee,
+ struct utrace_engine *engine,
+ enum utrace_resume_action action,
+ bool force_wakeup)
+{
+ if (force_wakeup) {
+ unsigned long flags;
+ /*
+ * Preserve the compatibility bug. Historically ptrace
+ * wakes up the tracee even if it should not. Clear
+ * SIGNAL_STOP_STOPPED for utrace_wakeup().
+ */
+ if (lock_task_sighand(tracee, &flags)) {
+ tracee->signal->flags &= ~SIGNAL_STOP_STOPPED;
+ unlock_task_sighand(tracee, &flags);
+ }
+ }
+
+ if (action != UTRACE_REPORT)
+ ptrace_context(engine)->stop_code = 0;
+ utrace_control(tracee, engine, action);
+}
+
+static void ptrace_detach_task(struct task_struct *tracee, int sig)
+{
+ /*
+ * If true, the caller is PTRACE_DETACH, otherwise
+ * the tracer detaches implicitly during exit.
+ */
+ bool voluntary = (sig >= 0);
+ struct utrace_engine *engine = ptrace_lookup_engine(tracee);
+ enum utrace_resume_action action = UTRACE_DETACH;
+
+ if (unlikely(IS_ERR(engine)))
+ return;
+
+ if (sig) {
+ struct ptrace_context *ctx = ptrace_context(engine);
+
+ switch (get_stop_event(ctx)) {
+ case PTRACE_EVENT_SYSCALL:
+ if (voluntary)
+ send_sig_info(sig, SEND_SIG_PRIV, tracee);
+ break;
+
+ case PTRACE_EVENT_SIGNAL:
+ if (voluntary)
+ ctx->signr = sig;
+ ctx->resume = UTRACE_DETACH;
+ action = UTRACE_RESUME;
+ break;
+ }
+ }
+
+ ptrace_wake_up(tracee, engine, action, voluntary);
+ utrace_engine_put(engine);
+}
+
+static void ptrace_abort_attach(struct task_struct *tracee)
+{
+ ptrace_detach_task(tracee, 0);
+}
+
+static u32 ptrace_report_exit(enum utrace_resume_action action,
+ struct utrace_engine *engine,
+ struct task_struct *task,
+ long orig_code, long *code)
+{
+ struct ptrace_context *ctx = ptrace_context(engine);
+
+ WARN_ON(ptrace_event_pending(ctx) &&
+ !signal_group_exit(task->signal));
+
+ set_stop_code(ctx, PTRACE_EVENT_EXIT);
+ ctx->eventmsg = *code;
+
+ return UTRACE_STOP;
+}
+
+static void ptrace_clone_attach(struct task_struct *parent,
+ struct task_struct *child,
+ int options)
+{
+ struct task_struct *tracer;
+ bool abort = true;
+
+ if (unlikely(ptrace_attach_task(child, options))) {
+ WARN_ON(1);
+ return;
+ }
+
+ write_lock_irq(&tasklist_lock);
+ tracer = parent->parent;
+ if (!(tracer->flags & PF_EXITING) && parent->ptrace) {
+ child->ptrace = parent->ptrace;
+ __ptrace_link(child, tracer);
+ abort = false;
+ }
+ write_unlock_irq(&tasklist_lock);
+ if (unlikely(abort)) {
+ ptrace_abort_attach(child);
+ return;
+ }
+
+ sigaddset(&child->pending.signal, SIGSTOP);
+ set_tsk_thread_flag(child, TIF_SIGPENDING);
+}
+
+/*
+ * Prevents sending SIGTRAP after tracehook_report_syscall_exit().
+ * Called when we are going to emulate the stop before SYSCALL_EXIT.
+ */
+static void suppress_sigtrap(struct task_struct *task)
+{
+ if (test_tsk_thread_flag(task, TIF_SINGLESTEP))
+ user_disable_single_step(task);
+}
+
+static u32 ptrace_report_clone(enum utrace_resume_action action,
+ struct utrace_engine *engine,
+ struct task_struct *parent,
+ unsigned long clone_flags,
+ struct task_struct *child)
+{
+ struct ptrace_context *ctx = ptrace_context(engine);
+ int event = 0;
+
+ WARN_ON(ptrace_event_pending(ctx));
+
+ if (clone_flags & CLONE_UNTRACED) {
+ /* no events reported */
+ } else if (clone_flags & CLONE_VFORK) {
+ if (ctx->options & PTRACE_O_TRACEVFORK)
+ event = PTRACE_EVENT_VFORK;
+ else if (ctx->options & PTRACE_O_TRACEVFORKDONE)
+ event = PTRACE_EVENT_VFORK_DONE;
+ } else if ((clone_flags & CSIGNAL) != SIGCHLD) {
+ if (ctx->options & PTRACE_O_TRACECLONE)
+ event = PTRACE_EVENT_CLONE;
+ } else if (ctx->options & PTRACE_O_TRACEFORK) {
+ event = PTRACE_EVENT_FORK;
+ }
+ /*
+ * Any of these reports implies auto-attaching the new child.
+ * So does CLONE_PTRACE, even with no event to report.
+ */
+ if ((event && event != PTRACE_EVENT_VFORK_DONE) ||
+ (clone_flags & CLONE_PTRACE))
+ ptrace_clone_attach(parent, child, ctx->options);
+
+ if (!event)
+ return UTRACE_RESUME;
+
+ suppress_sigtrap(parent);
+
+ set_stop_code(ctx, event);
+ ctx->eventmsg = child->pid;
+ /*
+ * We shouldn't stop now, inside the do_fork() path.
+ * We will stop later, before return to user-mode.
+ */
+ if (event == PTRACE_EVENT_VFORK_DONE)
+ return UTRACE_REPORT;
+ else
+ return UTRACE_STOP;
+}
+
+static inline void set_syscall_code(struct ptrace_context *ctx)
+{
+ set_stop_code(ctx, PTRACE_EVENT_SYSCALL);
+ if (ctx->options & PTRACE_O_TRACESYSGOOD)
+ ctx->stop_code |= 0x80;
+}
+
+static u32 ptrace_report_syscall_entry(u32 action,
+ struct utrace_engine *engine,
+ struct task_struct *task,
+ struct pt_regs *regs)
+{
+ struct ptrace_context *ctx = ptrace_context(engine);
+
+ if (action & UTRACE_SYSCALL_RESUMED) {
+ /*
+ * We already reported the first time.
+ * Nothing more to do now.
+ */
+ if (unlikely(ctx->options & PTRACE_O_SYSEMU))
+ return UTRACE_SYSCALL_ABORT | UTRACE_REPORT;
+ return utrace_syscall_action(action) | UTRACE_RESUME;
+ }
+
+ WARN_ON(ptrace_event_pending(ctx));
+
+ set_syscall_code(ctx);
+
+ if (unlikely(ctx->options & PTRACE_O_SYSEMU)) {
+ suppress_sigtrap(task);
+ return UTRACE_SYSCALL_ABORT | UTRACE_REPORT;
+ }
+
+ /*
+ * Stop now to report. We will get another callback after
+ * we resume, with the UTRACE_SYSCALL_RESUMED flag set.
+ */
+ return UTRACE_SYSCALL_RUN | UTRACE_STOP;
+}
+
+static u32 ptrace_report_syscall_exit(enum utrace_resume_action action,
+ struct utrace_engine *engine,
+ struct task_struct *task,
+ struct pt_regs *regs)
+{
+ struct ptrace_context *ctx = ptrace_context(engine);
+
+ if (ptrace_event_pending(ctx))
+ return UTRACE_STOP;
+
+ if (ctx->resume != UTRACE_RESUME) {
+ WARN_ON(ctx->resume != UTRACE_BLOCKSTEP &&
+ ctx->resume != UTRACE_SINGLESTEP);
+ ctx->resume = UTRACE_RESUME;
+
+ ctx->signr = SIGTRAP;
+ return UTRACE_INTERRUPT;
+ }
+
+ set_syscall_code(ctx);
+ return UTRACE_STOP;
+}
+
+static u32 ptrace_report_exec(enum utrace_resume_action action,
+ struct utrace_engine *engine,
+ struct task_struct *task,
+ const struct linux_binfmt *fmt,
+ const struct linux_binprm *bprm,
+ struct pt_regs *regs)
+{
+ struct ptrace_context *ctx = ptrace_context(engine);
+
+ WARN_ON(ptrace_event_pending(ctx));
+
+ if (!(ctx->options & PTRACE_O_TRACEEXEC)) {
+ /*
+ * Old-fashioned ptrace'd exec just posts a plain signal.
+ */
+ send_sig(SIGTRAP, task, 0);
+ return UTRACE_RESUME;
+ }
+
+ suppress_sigtrap(task);
+ set_stop_code(ctx, PTRACE_EVENT_EXEC);
+
+ return UTRACE_STOP;
+}
+
+static void ptrace_send_sigtrap(struct task_struct *task, siginfo_t *info)
+{
+ user_single_step_siginfo(task, task_pt_regs(task), info);
+ force_sig_info(SIGTRAP, info, task);
+}
+
+static enum utrace_signal_action resume_signal(struct task_struct *task,
+ struct ptrace_context *ctx,
+ struct k_sigaction *return_ka)
+{
+ siginfo_t *info = ctx->siginfo;
+ int signr = ctx->signr;
+
+ ctx->siginfo = NULL;
+ ctx->signr = 0;
+
+ /* Did the debugger cancel the sig? */
+ if (!signr)
+ return UTRACE_SIGNAL_IGN;
+ /*
+ * Update the siginfo structure if the signal has changed.
+ * If the debugger wanted something specific in the siginfo
+ * then it should have updated *info via PTRACE_SETSIGINFO.
+ */
+ if (info->si_signo != signr) {
+ info->si_signo = signr;
+ info->si_errno = 0;
+ info->si_code = SI_USER;
+ info->si_pid = task_pid_vnr(current->parent);
+ info->si_uid = task_uid(current->parent);
+ }
+
+ /* If the (new) signal is now blocked, requeue it. */
+ if (sigismember(&task->blocked, signr)) {
+ send_sig_info(signr, info, task);
+ return UTRACE_SIGNAL_IGN;
+ }
+
+ spin_lock_irq(&task->sighand->siglock);
+ *return_ka = task->sighand->action[signr - 1];
+ spin_unlock_irq(&task->sighand->siglock);
+
+ return UTRACE_SIGNAL_DELIVER;
+}
+
+static u32 ptrace_report_signal(u32 action,
+ struct utrace_engine *engine,
+ struct task_struct *task,
+ struct pt_regs *regs,
+ siginfo_t *info,
+ const struct k_sigaction *orig_ka,
+ struct k_sigaction *return_ka)
+{
+ struct ptrace_context *ctx = ptrace_context(engine);
+ enum utrace_resume_action resume = ctx->resume;
+
+ if (ptrace_event_pending(ctx)) {
+ action = utrace_signal_action(action);
+ WARN_ON(action != UTRACE_SIGNAL_REPORT);
+ return action | UTRACE_STOP;
+ }
+
+ switch (utrace_signal_action(action)) {
+ case UTRACE_SIGNAL_HANDLER:
+ if (WARN_ON(ctx->siginfo))
+ ctx->siginfo = NULL;
+
+ if (resume != UTRACE_RESUME) {
+ WARN_ON(resume != UTRACE_BLOCKSTEP &&
+ resume != UTRACE_SINGLESTEP);
+
+ set_stop_code(ctx, PTRACE_EVENT_SIGTRAP);
+ return UTRACE_STOP | UTRACE_SIGNAL_IGN;
+ }
+
+ case UTRACE_SIGNAL_REPORT:
+ if (!ctx->siginfo) {
+ if (ctx->signr) {
+ /* set by ptrace_resume(SYSCALL_EXIT) */
+ WARN_ON(ctx->signr != SIGTRAP);
+ ptrace_send_sigtrap(task, info);
+ }
+
+ return resume | UTRACE_SIGNAL_IGN;
+ }
+
+ if (WARN_ON(ctx->siginfo != info))
+ return resume | UTRACE_SIGNAL_IGN;
+
+ return resume | resume_signal(task, ctx, return_ka);
+
+ default:
+ break;
+ }
+
+ WARN_ON(ctx->siginfo);
+ ctx->siginfo = info;
+ /*
+ * ctx->siginfo points to the caller's stack.
+ * Make sure the subsequent UTRACE_SIGNAL_REPORT clears
+ * ->siginfo before return from get_signal_to_deliver().
+ */
+ utrace_control(task, engine, UTRACE_INTERRUPT);
+
+ ctx->signr = info->si_signo;
+ ctx->stop_code = (PTRACE_EVENT_SIGNAL << 8) | ctx->signr;
+
+ return UTRACE_STOP | UTRACE_SIGNAL_IGN;
+}
+
+static u32 ptrace_report_quiesce(u32 action,
+ struct utrace_engine *engine,
+ struct task_struct *task,
+ unsigned long event)
+{
+ struct ptrace_context *ctx = ptrace_context(engine);
+
+ if (ptrace_event_pending(ctx))
+ return UTRACE_STOP;
+
+ return event ? UTRACE_RESUME : ctx->resume;
+}
+
+static void ptrace_release(void *data)
+{
+ kfree(data);
+}
+
+static const struct utrace_engine_ops ptrace_utrace_ops = {
+ .report_signal = ptrace_report_signal,
+ .report_quiesce = ptrace_report_quiesce,
+ .report_exec = ptrace_report_exec,
+ .report_exit = ptrace_report_exit,
+ .report_clone = ptrace_report_clone,
+ .report_syscall_entry = ptrace_report_syscall_entry,
+ .report_syscall_exit = ptrace_report_syscall_exit,
+ .release = ptrace_release,
+};
+
+int ptrace_check_attach(struct task_struct *child, int kill)
+{
+ struct utrace_engine *engine;
+ struct utrace_examiner exam;
+ int ret = -ESRCH;
+
+ engine = ptrace_lookup_engine(child);
+ if (IS_ERR(engine))
+ return ret;
+
+ if (child->parent != current)
+ goto out;
+
+ if (unlikely(kill))
+ ret = 0;
+
+ if (!task_is_stopped_or_traced(child))
+ goto out;
+ /*
+ * Make sure our engine has already stopped the child.
+ * Then wait for it to be off the CPU.
+ */
+ if (!utrace_control(child, engine, UTRACE_STOP) &&
+ !utrace_prepare_examine(child, engine, &exam))
+ ret = 0;
+out:
+ utrace_engine_put(engine);
+ return ret;
+}
+
+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;
+
+ retval = ptrace_attach_task(task, 0);
+ if (unlikely(retval))
+ goto unlock_creds;
+
+ write_lock_irq(&tasklist_lock);
+ retval = -EPERM;
+ if (unlikely(task->exit_state))
+ goto unlock_tasklist;
+
+ BUG_ON(task->ptrace);
+ task->ptrace = PT_UTRACED;
+ 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;
+}
+
+/*
+ * Performs checks and sets PT_UTRACED.
+ * Should be used by all ptrace implementations for PTRACE_TRACEME.
+ */
+int ptrace_traceme(void)
+{
+ bool detach = true;
+ int ret = ptrace_attach_task(current, 0);
+
+ if (unlikely(ret))
+ return ret;
+
+ ret = -EPERM;
+ write_lock_irq(&tasklist_lock);
+ BUG_ON(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_UTRACED;
+ __ptrace_link(current, current->real_parent);
+ detach = false;
+ }
+ write_unlock_irq(&tasklist_lock);
+
+ if (detach)
+ ptrace_abort_attach(current);
+ return ret;
+}
+
+static void ptrace_do_detach(struct task_struct *tracee, unsigned int data)
+{
+ bool detach, release;
+
+ write_lock_irq(&tasklist_lock);
+ /*
+ * This tracee can be already killed. Make sure de_thread() or
+ * our sub-thread doing do_wait() didn't do release_task() yet.
+ */
+ detach = tracee->ptrace != 0;
+ release = false;
+ if (likely(detach))
+ release = __ptrace_detach(current, tracee);
+ write_unlock_irq(&tasklist_lock);
+
+ if (unlikely(release))
+ release_task(tracee);
+ else if (likely(detach))
+ ptrace_detach_task(tracee, data);
+}
+
+int ptrace_detach(struct task_struct *child, unsigned int data)
+{
+ if (!valid_signal(data))
+ return -EIO;
+
+ ptrace_do_detach(child, data);
+
+ return 0;
+}
+
+/*
+ * Detach all tasks we were using ptrace on.
+ */
+void exit_ptrace(struct task_struct *tracer)
+{
+ for (;;) {
+ struct task_struct *tracee = NULL;
+
+ read_lock(&tasklist_lock);
+ if (!list_empty(&tracer->ptraced)) {
+ tracee = list_first_entry(&tracer->ptraced,
+ struct task_struct, ptrace_entry);
+ get_task_struct(tracee);
+ }
+ read_unlock(&tasklist_lock);
+ if (!tracee)
+ break;
+
+ ptrace_do_detach(tracee, -1);
+ put_task_struct(tracee);
+ }
+}
+
+static int ptrace_set_options(struct task_struct *tracee,
+ struct utrace_engine *engine, long data)
+{
+ BUILD_BUG_ON(PTRACE_O_MASK & PTRACE_O_SYSEMU);
+
+ ptrace_set_events(tracee, engine, data & PTRACE_O_MASK);
+ return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
+}
+
+static int ptrace_rw_siginfo(struct task_struct *tracee,
+ struct ptrace_context *ctx,
+ siginfo_t *info, bool write)
+{
+ unsigned long flags;
+ int err;
+
+ switch (get_stop_event(ctx)) {
+ case 0: /* jctl stop */
+ return -EINVAL;
+
+ case PTRACE_EVENT_SIGNAL:
+ err = -ESRCH;
+ if (lock_task_sighand(tracee, &flags)) {
+ if (likely(task_is_traced(tracee))) {
+ if (write)
+ *ctx->siginfo = *info;
+ else
+ *info = *ctx->siginfo;
+ err = 0;
+ }
+ unlock_task_sighand(tracee, &flags);
+ }
+
+ return err;
+
+ default:
+ if (!write) {
+ memset(info, 0, sizeof(*info));
+ info->si_signo = SIGTRAP;
+ info->si_code = ctx->stop_code & PTRACE_EVENT_MASK;
+ info->si_pid = task_pid_vnr(tracee);
+ info->si_uid = task_uid(tracee);
+ }
+
+ return 0;
+ }
+}
+
+static void do_ptrace_notify_stop(struct ptrace_context *ctx,
+ struct task_struct *tracee)
+{
+ /*
+ * This can race with SIGKILL, but we borrow this race from
+ * the old ptrace implementation. ->exit_code is only needed
+ * for wait_task_stopped()->task_stopped_code(), we should
+ * change it to use ptrace_context.
+ */
+ tracee->exit_code = ctx->stop_code & PTRACE_EVENT_MASK;
+ WARN_ON(!tracee->exit_code);
+
+ read_lock(&tasklist_lock);
+ /*
+ * Don't want to allow preemption here, because
+ * sys_ptrace() needs this task to be inactive.
+ */
+ preempt_disable();
+ /*
+ * It can be killed and then released by our subthread,
+ * or ptrace_attach() has not completed yet.
+ */
+ if (task_ptrace(tracee))
+ do_notify_parent_cldstop(tracee, CLD_TRAPPED);
+ read_unlock(&tasklist_lock);
+ preempt_enable_no_resched();
+}
+
+void ptrace_notify_stop(struct task_struct *tracee)
+{
+ struct utrace_engine *engine = ptrace_lookup_engine(tracee);
+
+ if (IS_ERR(engine))
+ return;
+
+ do_ptrace_notify_stop(ptrace_context(engine), tracee);
+ utrace_engine_put(engine);
+}
+
+static int ptrace_resume_action(struct task_struct *tracee,
+ struct utrace_engine *engine, long request)
+{
+ struct ptrace_context *ctx = ptrace_context(engine);
+ unsigned long events;
+ int action;
+
+ ctx->options &= ~PTRACE_O_SYSEMU;
+ events = engine->flags & ~UTRACE_EVENT_SYSCALL;
+ action = UTRACE_RESUME;
+
+ switch (request) {
+#ifdef PTRACE_SINGLEBLOCK
+ case PTRACE_SINGLEBLOCK:
+ if (unlikely(!arch_has_block_step()))
+ return -EIO;
+ action = UTRACE_BLOCKSTEP;
+ events |= UTRACE_EVENT(SYSCALL_EXIT);
+ break;
+#endif
+
+#ifdef PTRACE_SINGLESTEP
+ case PTRACE_SINGLESTEP:
+ if (unlikely(!arch_has_single_step()))
+ return -EIO;
+ action = UTRACE_SINGLESTEP;
+ events |= UTRACE_EVENT(SYSCALL_EXIT);
+ break;
+#endif
+
+#ifdef PTRACE_SYSEMU
+ case PTRACE_SYSEMU_SINGLESTEP:
+ if (unlikely(!arch_has_single_step()))
+ return -EIO;
+ action = UTRACE_SINGLESTEP;
+ case PTRACE_SYSEMU:
+ ctx->options |= PTRACE_O_SYSEMU;
+ events |= UTRACE_EVENT(SYSCALL_ENTRY);
+ break;
+#endif
+
+ case PTRACE_SYSCALL:
+ events |= UTRACE_EVENT_SYSCALL;
+ break;
+
+ case PTRACE_CONT:
+ break;
+ default:
+ return -EIO;
+ }
+
+ if (events != engine->flags &&
+ utrace_set_events(tracee, engine, events))
+ return -ESRCH;
+
+ return action;
+}
+
+static int ptrace_resume(struct task_struct *tracee,
+ struct utrace_engine *engine,
+ long request, long data)
+{
+ struct ptrace_context *ctx = ptrace_context(engine);
+ int action;
+
+ if (!valid_signal(data))
+ return -EIO;
+
+ action = ptrace_resume_action(tracee, engine, request);
+ if (action < 0)
+ return action;
+
+ switch (get_stop_event(ctx)) {
+ case PTRACE_EVENT_VFORK:
+ if (ctx->options & PTRACE_O_TRACEVFORKDONE) {
+ set_stop_code(ctx, PTRACE_EVENT_VFORK_DONE);
+ action = UTRACE_REPORT;
+ }
+ break;
+
+ case PTRACE_EVENT_EXEC:
+ case PTRACE_EVENT_FORK:
+ case PTRACE_EVENT_CLONE:
+ case PTRACE_EVENT_VFORK_DONE:
+ if (request == PTRACE_SYSCALL) {
+ set_syscall_code(ctx);
+ do_ptrace_notify_stop(ctx, tracee);
+ return 0;
+ }
+
+ if (action != UTRACE_RESUME) {
+ /*
+ * single-stepping. UTRACE_SIGNAL_REPORT will
+ * synthesize a trap to follow the syscall insn.
+ */
+ ctx->signr = SIGTRAP;
+ action = UTRACE_INTERRUPT;
+ }
+ break;
+
+ case PTRACE_EVENT_SYSCALL:
+ if (data)
+ send_sig_info(data, SEND_SIG_PRIV, tracee);
+ break;
+
+ case PTRACE_EVENT_SIGNAL:
+ ctx->signr = data;
+ break;
+ }
+
+ ctx->resume = action;
+ ptrace_wake_up(tracee, engine, action, true);
+ return 0;
+}
+
+int ptrace_request(struct task_struct *child, long request,
+ long addr, long data)
+{
+ struct utrace_engine *engine = ptrace_lookup_engine(child);
+ siginfo_t siginfo;
+ int ret;
+
+ if (unlikely(IS_ERR(engine)))
+ return -ESRCH;
+
+ switch (request) {
+ case PTRACE_PEEKTEXT:
+ case PTRACE_PEEKDATA:
+ ret = generic_ptrace_peekdata(child, addr, data);
+ break;
+ case PTRACE_POKETEXT:
+ case PTRACE_POKEDATA:
+ ret = generic_ptrace_pokedata(child, addr, data);
+ break;
+
+#ifdef PTRACE_OLDSETOPTIONS
+ case PTRACE_OLDSETOPTIONS:
+#endif
+ case PTRACE_SETOPTIONS:
+ ret = ptrace_set_options(child, engine, data);
+ break;
+ case PTRACE_GETEVENTMSG:
+ ret = put_user(ptrace_context(engine)->eventmsg,
+ (unsigned long __user *) data);
+ break;
+
+ case PTRACE_GETSIGINFO:
+ ret = ptrace_rw_siginfo(child, ptrace_context(engine),
+ &siginfo, false);
+ 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_rw_siginfo(child, ptrace_context(engine),
+ &siginfo, true);
+ break;
+
+ case PTRACE_DETACH: /* detach a process that was attached. */
+ ret = ptrace_detach(child, data);
+ break;
+
+ case PTRACE_KILL:
+ /* Ugly historical behaviour. */
+ if (task_is_traced(child))
+ ptrace_resume(child, engine, PTRACE_CONT, SIGKILL);
+ ret = 0;
+ break;
+
+ default:
+ ret = ptrace_resume(child, engine, request, data);
+ break;
+ }
+
+ utrace_engine_put(engine);
+ return ret;
+}
+
+#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)
+{
+ struct utrace_engine *engine = ptrace_lookup_engine(child);
+ compat_ulong_t __user *datap = compat_ptr(data);
+ compat_ulong_t word;
+ siginfo_t siginfo;
+ int ret;
+
+ if (unlikely(IS_ERR(engine)))
+ return -ESRCH;
+
+ 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)ptrace_context(engine)->eventmsg,
+ datap);
+ break;
+
+ case PTRACE_GETSIGINFO:
+ ret = ptrace_rw_siginfo(child, ptrace_context(engine),
+ &siginfo, false);
+ 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_rw_siginfo(child, ptrace_context(engine),
+ &siginfo, true);
+ break;
+
+ default:
+ ret = ptrace_request(child, request, addr, data);
+ }
+
+ utrace_engine_put(engine);
+ return ret;
+}
+#endif /* CONFIG_COMPAT */
--
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