diff options
Diffstat (limited to 'include/linux/ptrace.h')
| -rw-r--r-- | include/linux/ptrace.h | 484 |
1 files changed, 484 insertions, 0 deletions
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h new file mode 100644 index 000000000..c952c5ba8 --- /dev/null +++ b/include/linux/ptrace.h @@ -0,0 +1,484 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_PTRACE_H +#define _LINUX_PTRACE_H + +#include <linux/compiler.h> /* For unlikely. */ +#include <linux/sched.h> /* For struct task_struct. */ +#include <linux/sched/signal.h> /* For send_sig(), same_thread_group(), etc. */ +#include <linux/err.h> /* for IS_ERR_VALUE */ +#include <linux/bug.h> /* For BUG_ON. */ +#include <linux/pid_namespace.h> /* For task_active_pid_ns. */ +#include <uapi/linux/ptrace.h> +#include <linux/seccomp.h> + +/* Add sp to seccomp_data, as seccomp is user API, we don't want to modify it */ +struct syscall_info { + __u64 sp; + struct seccomp_data data; +}; + +extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr, + void *buf, int len, unsigned int gup_flags); + +/* + * Ptrace flags + * + * The owner ship rules for task->ptrace which holds the ptrace + * flags is simple. When a task is running it owns it's task->ptrace + * flags. When the a task is stopped the ptracer owns task->ptrace. + */ + +#define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */ +#define PT_PTRACED 0x00000001 + +#define PT_OPT_FLAG_SHIFT 3 +/* PT_TRACE_* event enable flags */ +#define PT_EVENT_FLAG(event) (1 << (PT_OPT_FLAG_SHIFT + (event))) +#define PT_TRACESYSGOOD PT_EVENT_FLAG(0) +#define PT_TRACE_FORK PT_EVENT_FLAG(PTRACE_EVENT_FORK) +#define PT_TRACE_VFORK PT_EVENT_FLAG(PTRACE_EVENT_VFORK) +#define PT_TRACE_CLONE PT_EVENT_FLAG(PTRACE_EVENT_CLONE) +#define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC) +#define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE) +#define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT) +#define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP) + +#define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT) +#define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT) + +extern long arch_ptrace(struct task_struct *child, long request, + unsigned long addr, unsigned long data); +extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len); +extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len); +extern void ptrace_disable(struct task_struct *); +extern int ptrace_request(struct task_struct *child, long request, + unsigned long addr, unsigned long data); +extern int ptrace_notify(int exit_code, unsigned long message); +extern void __ptrace_link(struct task_struct *child, + struct task_struct *new_parent, + const struct cred *ptracer_cred); +extern void __ptrace_unlink(struct task_struct *child); +extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead); +#define PTRACE_MODE_READ 0x01 +#define PTRACE_MODE_ATTACH 0x02 +#define PTRACE_MODE_NOAUDIT 0x04 +#define PTRACE_MODE_FSCREDS 0x08 +#define PTRACE_MODE_REALCREDS 0x10 + +/* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */ +#define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS) +#define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS) +#define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS) +#define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS) + +/** + * ptrace_may_access - check whether the caller is permitted to access + * a target task. + * @task: target task + * @mode: selects type of access and caller credentials + * + * Returns true on success, false on denial. + * + * One of the flags PTRACE_MODE_FSCREDS and PTRACE_MODE_REALCREDS must + * be set in @mode to specify whether the access was requested through + * a filesystem syscall (should use effective capabilities and fsuid + * of the caller) or through an explicit syscall such as + * process_vm_writev or ptrace (and should use the real credentials). + */ +extern bool ptrace_may_access(struct task_struct *task, unsigned int mode); + +static inline int ptrace_reparented(struct task_struct *child) +{ + return !same_thread_group(child->real_parent, child->parent); +} + +static inline void ptrace_unlink(struct task_struct *child) +{ + if (unlikely(child->ptrace)) + __ptrace_unlink(child); +} + +int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr, + unsigned long data); +int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr, + unsigned long data); + +/** + * ptrace_parent - return the task that is tracing the given task + * @task: task to consider + * + * Returns %NULL if no one is tracing @task, or the &struct task_struct + * pointer to its tracer. + * + * Must called under rcu_read_lock(). The pointer returned might be kept + * live only by RCU. During exec, this may be called with task_lock() held + * on @task, still held from when check_unsafe_exec() was called. + */ +static inline struct task_struct *ptrace_parent(struct task_struct *task) +{ + if (unlikely(task->ptrace)) + return rcu_dereference(task->parent); + return NULL; +} + +/** + * ptrace_event_enabled - test whether a ptrace event is enabled + * @task: ptracee of interest + * @event: %PTRACE_EVENT_* to test + * + * Test whether @event is enabled for ptracee @task. + * + * Returns %true if @event is enabled, %false otherwise. + */ +static inline bool ptrace_event_enabled(struct task_struct *task, int event) +{ + return task->ptrace & PT_EVENT_FLAG(event); +} + +/** + * ptrace_event - possibly stop for a ptrace event notification + * @event: %PTRACE_EVENT_* value to report + * @message: value for %PTRACE_GETEVENTMSG to return + * + * Check whether @event is enabled and, if so, report @event and @message + * to the ptrace parent. + * + * Called without locks. + */ +static inline void ptrace_event(int event, unsigned long message) +{ + if (unlikely(ptrace_event_enabled(current, event))) { + ptrace_notify((event << 8) | SIGTRAP, message); + } else if (event == PTRACE_EVENT_EXEC) { + /* legacy EXEC report via SIGTRAP */ + if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED) + send_sig(SIGTRAP, current, 0); + } +} + +/** + * ptrace_event_pid - possibly stop for a ptrace event notification + * @event: %PTRACE_EVENT_* value to report + * @pid: process identifier for %PTRACE_GETEVENTMSG to return + * + * Check whether @event is enabled and, if so, report @event and @pid + * to the ptrace parent. @pid is reported as the pid_t seen from the + * ptrace parent's pid namespace. + * + * Called without locks. + */ +static inline void ptrace_event_pid(int event, struct pid *pid) +{ + /* + * FIXME: There's a potential race if a ptracer in a different pid + * namespace than parent attaches between computing message below and + * when we acquire tasklist_lock in ptrace_stop(). If this happens, + * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG. + */ + unsigned long message = 0; + struct pid_namespace *ns; + + rcu_read_lock(); + ns = task_active_pid_ns(rcu_dereference(current->parent)); + if (ns) + message = pid_nr_ns(pid, ns); + rcu_read_unlock(); + + ptrace_event(event, message); +} + +/** + * ptrace_init_task - initialize ptrace state for a new child + * @child: new child task + * @ptrace: true if child should be ptrace'd by parent's tracer + * + * This is called immediately after adding @child to its parent's children + * list. @ptrace is false in the normal case, and true to ptrace @child. + * + * Called with current's siglock and write_lock_irq(&tasklist_lock) held. + */ +static inline void ptrace_init_task(struct task_struct *child, bool ptrace) +{ + INIT_LIST_HEAD(&child->ptrace_entry); + INIT_LIST_HEAD(&child->ptraced); + child->jobctl = 0; + child->ptrace = 0; + child->parent = child->real_parent; + + if (unlikely(ptrace) && current->ptrace) { + child->ptrace = current->ptrace; + __ptrace_link(child, current->parent, current->ptracer_cred); + + if (child->ptrace & PT_SEIZED) + task_set_jobctl_pending(child, JOBCTL_TRAP_STOP); + else + sigaddset(&child->pending.signal, SIGSTOP); + } + else + child->ptracer_cred = NULL; +} + +/** + * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped + * @task: task in %EXIT_DEAD state + * + * Called with write_lock(&tasklist_lock) held. + */ +static inline void ptrace_release_task(struct task_struct *task) +{ + BUG_ON(!list_empty(&task->ptraced)); + ptrace_unlink(task); + BUG_ON(!list_empty(&task->ptrace_entry)); +} + +#ifndef force_successful_syscall_return +/* + * System call handlers that, upon successful completion, need to return a + * negative value should call force_successful_syscall_return() right before + * returning. On architectures where the syscall convention provides for a + * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly + * others), this macro can be used to ensure that the error flag will not get + * set. On architectures which do not support a separate error flag, the macro + * is a no-op and the spurious error condition needs to be filtered out by some + * other means (e.g., in user-level, by passing an extra argument to the + * syscall handler, or something along those lines). + */ +#define force_successful_syscall_return() do { } while (0) +#endif + +#ifndef is_syscall_success +/* + * On most systems we can tell if a syscall is a success based on if the retval + * is an error value. On some systems like ia64 and powerpc they have different + * indicators of success/failure and must define their own. + */ +#define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs)))) +#endif + +/* + * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__. + * + * These do-nothing inlines are used when the arch does not + * implement single-step. The kerneldoc comments are here + * to document the interface for all arch definitions. + */ + +#ifndef arch_has_single_step +/** + * arch_has_single_step - does this CPU support user-mode single-step? + * + * If this is defined, then there must be function declarations or + * inlines for user_enable_single_step() and user_disable_single_step(). + * arch_has_single_step() should evaluate to nonzero iff the machine + * supports instruction single-step for user mode. + * It can be a constant or it can test a CPU feature bit. + */ +#define arch_has_single_step() (0) + +/** + * user_enable_single_step - single-step in user-mode task + * @task: either current or a task stopped in %TASK_TRACED + * + * This can only be called when arch_has_single_step() has returned nonzero. + * Set @task so that when it returns to user mode, it will trap after the + * next single instruction executes. If arch_has_block_step() is defined, + * this must clear the effects of user_enable_block_step() too. + */ +static inline void user_enable_single_step(struct task_struct *task) +{ + BUG(); /* This can never be called. */ +} + +/** + * user_disable_single_step - cancel user-mode single-step + * @task: either current or a task stopped in %TASK_TRACED + * + * Clear @task of the effects of user_enable_single_step() and + * user_enable_block_step(). This can be called whether or not either + * of those was ever called on @task, and even if arch_has_single_step() + * returned zero. + */ +static inline void user_disable_single_step(struct task_struct *task) +{ +} +#else +extern void user_enable_single_step(struct task_struct *); +extern void user_disable_single_step(struct task_struct *); +#endif /* arch_has_single_step */ + +#ifndef arch_has_block_step +/** + * arch_has_block_step - does this CPU support user-mode block-step? + * + * If this is defined, then there must be a function declaration or inline + * for user_enable_block_step(), and arch_has_single_step() must be defined + * too. arch_has_block_step() should evaluate to nonzero iff the machine + * supports step-until-branch for user mode. It can be a constant or it + * can test a CPU feature bit. + */ +#define arch_has_block_step() (0) + +/** + * user_enable_block_step - step until branch in user-mode task + * @task: either current or a task stopped in %TASK_TRACED + * + * This can only be called when arch_has_block_step() has returned nonzero, + * and will never be called when single-instruction stepping is being used. + * Set @task so that when it returns to user mode, it will trap after the + * next branch or trap taken. + */ +static inline void user_enable_block_step(struct task_struct *task) +{ + BUG(); /* This can never be called. */ +} +#else +extern void user_enable_block_step(struct task_struct *); +#endif /* arch_has_block_step */ + +#ifdef ARCH_HAS_USER_SINGLE_STEP_REPORT +extern void user_single_step_report(struct pt_regs *regs); +#else +static inline void user_single_step_report(struct pt_regs *regs) +{ + kernel_siginfo_t info; + clear_siginfo(&info); + info.si_signo = SIGTRAP; + info.si_errno = 0; + info.si_code = SI_USER; + info.si_pid = 0; + info.si_uid = 0; + force_sig_info(&info); +} +#endif + +#ifndef arch_ptrace_stop_needed +/** + * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called + * + * This is called with the siglock held, to decide whether or not it's + * necessary to release the siglock and call arch_ptrace_stop(). It can be + * defined to a constant if arch_ptrace_stop() is never required, or always + * is. On machines where this makes sense, it should be defined to a quick + * test to optimize out calling arch_ptrace_stop() when it would be + * superfluous. For example, if the thread has not been back to user mode + * since the last stop, the thread state might indicate that nothing needs + * to be done. + * + * This is guaranteed to be invoked once before a task stops for ptrace and + * may include arch-specific operations necessary prior to a ptrace stop. + */ +#define arch_ptrace_stop_needed() (0) +#endif + +#ifndef arch_ptrace_stop +/** + * arch_ptrace_stop - Do machine-specific work before stopping for ptrace + * + * This is called with no locks held when arch_ptrace_stop_needed() has + * just returned nonzero. It is allowed to block, e.g. for user memory + * access. The arch can have machine-specific work to be done before + * ptrace stops. On ia64, register backing store gets written back to user + * memory here. Since this can be costly (requires dropping the siglock), + * we only do it when the arch requires it for this particular stop, as + * indicated by arch_ptrace_stop_needed(). + */ +#define arch_ptrace_stop() do { } while (0) +#endif + +#ifndef current_pt_regs +#define current_pt_regs() task_pt_regs(current) +#endif + +/* + * unlike current_pt_regs(), this one is equal to task_pt_regs(current) + * on *all* architectures; the only reason to have a per-arch definition + * is optimisation. + */ +#ifndef signal_pt_regs +#define signal_pt_regs() task_pt_regs(current) +#endif + +#ifndef current_user_stack_pointer +#define current_user_stack_pointer() user_stack_pointer(current_pt_regs()) +#endif + +extern int task_current_syscall(struct task_struct *target, struct syscall_info *info); + +extern void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact); + +/* + * ptrace report for syscall entry and exit looks identical. + */ +static inline int ptrace_report_syscall(unsigned long message) +{ + int ptrace = current->ptrace; + int signr; + + if (!(ptrace & PT_PTRACED)) + return 0; + + signr = ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0), + message); + + /* + * this isn't the same as continuing with a signal, but it will do + * for normal use. strace only continues with a signal if the + * stopping signal is not SIGTRAP. -brl + */ + if (signr) + send_sig(signr, current, 1); + + return fatal_signal_pending(current); +} + +/** + * ptrace_report_syscall_entry - task is about to attempt a system call + * @regs: user register state of current task + * + * This will be called if %SYSCALL_WORK_SYSCALL_TRACE or + * %SYSCALL_WORK_SYSCALL_EMU have been set, when the current task has just + * entered the kernel for a system call. Full user register state is + * available here. Changing the values in @regs can affect the system + * call number and arguments to be tried. It is safe to block here, + * preventing the system call from beginning. + * + * Returns zero normally, or nonzero if the calling arch code should abort + * the system call. That must prevent normal entry so no system call is + * made. If @task ever returns to user mode after this, its register state + * is unspecified, but should be something harmless like an %ENOSYS error + * return. It should preserve enough information so that syscall_rollback() + * can work (see asm-generic/syscall.h). + * + * Called without locks, just after entering kernel mode. + */ +static inline __must_check int ptrace_report_syscall_entry( + struct pt_regs *regs) +{ + return ptrace_report_syscall(PTRACE_EVENTMSG_SYSCALL_ENTRY); +} + +/** + * ptrace_report_syscall_exit - task has just finished a system call + * @regs: user register state of current task + * @step: nonzero if simulating single-step or block-step + * + * This will be called if %SYSCALL_WORK_SYSCALL_TRACE has been set, when + * the current task has just finished an attempted system call. Full + * user register state is available here. It is safe to block here, + * preventing signals from being processed. + * + * If @step is nonzero, this report is also in lieu of the normal + * trap that would follow the system call instruction because + * user_enable_block_step() or user_enable_single_step() was used. + * In this case, %SYSCALL_WORK_SYSCALL_TRACE might not be set. + * + * Called without locks, just before checking for pending signals. + */ +static inline void ptrace_report_syscall_exit(struct pt_regs *regs, int step) +{ + if (step) + user_single_step_report(regs); + else + ptrace_report_syscall(PTRACE_EVENTMSG_SYSCALL_EXIT); +} +#endif |