ptrace实现PT_DENY_ATTACH,就是对相关进程proc的p_lflag加上P_LNOATTACH标示位。那么要想使得进程和被调试器加载,只需要取消这个标志位。现在的问题是,proc链表结构,是位于iOS内核中,所以我们必须要拥有读写iOS内核的能力,要获取这个能力,第一个想到的办法是对iOS的漏洞利用,毕竟,iOS越狱也是基于这些漏洞,对特定内核位置进行读写。所幸的是,当前一些越狱工具,提供了tfp0(task for pid 0)接口,可供我们读写iOS内核。 那什么是tfp0呢?theiphonewiki上给出的说明如下: In the XNU kernel, task_for_pid is a function that allows a (privileged) process to get the task port of another process on the same host, except the kernel task (process ID 0). A tfp0 patch (or task_for_pid(0) patch) removes this restriction, allowing any executable running as root to call task_for_pid for pid 0 (hence the name) and then use vm_read and vm_write to modify the kernel VM region. The entitlements get-task-allow and task_for_pid-allow are required to make AMFI happy. https://www.theiphonewiki.com/wiki/Tfp0_patch
https://github.com/tututu-patch/iOSFuckDenyAttach iPhone 8 Plus iOS 13.6 , Darwin Kernel Version 19.6.0: Sat Jun 27 04:36:08 PDT 2020; root:xnu-6153.142.1~4/RELEASE_ARM64_T8015
struct proc {
LIST_ENTRY(proc) p_list; /* List of all processes. */
void * XNU_PTRAUTH_SIGNED_PTR("proc.task") task; /* corresponding task (static)*/
struct proc * XNU_PTRAUTH_SIGNED_PTR("proc.p_pptr") p_pptr; /* Pointer to parent process.(LL) */
pid_t p_ppid; /* process's parent pid number */
pid_t p_original_ppid; /* process's original parent pid number, doesn't change if reparented */
pid_t p_pgrpid; /* process group id of the process (LL)*/
uid_t p_uid;
gid_t p_gid;
uid_t p_ruid;
gid_t p_rgid;
uid_t p_svuid;
gid_t p_svgid;
uint64_t p_uniqueid; /* process unique ID - incremented on fork/spawn/vfork, remains same across exec. */
uint64_t p_puniqueid; /* parent's unique ID - set on fork/spawn/vfork, doesn't change if reparented. */
lck_mtx_t p_mlock; /* mutex lock for proc */
pid_t p_pid; /* Process identifier. (static)*/
char p_stat; /* S* process status. (PL)*/
char p_shutdownstate;
char p_kdebug; /* P_KDEBUG eq (CC)*/
char p_btrace; /* P_BTRACE eq (CC)*/
LIST_ENTRY(proc) p_pglist; /* List of processes in pgrp.(PGL) */
LIST_ENTRY(proc) p_sibling; /* List of sibling processes. (LL)*/
LIST_HEAD(, proc) p_children; /* Pointer to list of children. (LL)*/
TAILQ_HEAD(, uthread) p_uthlist; /* List of uthreads (PL) */
LIST_ENTRY(proc) p_hash; /* Hash chain. (LL)*/
#if CONFIG_PERSONAS
struct persona *p_persona;
LIST_ENTRY(proc) p_persona_list;
#endif
lck_mtx_t p_fdmlock; /* proc lock to protect fdesc */
lck_mtx_t p_ucred_mlock; /* mutex lock to protect p_ucred */
/* substructures: */
kauth_cred_t XNU_PTRAUTH_SIGNED_PTR("proc.p_ucred") p_ucred; /* Process owner's identity. (PUCL) */
struct filedesc *p_fd; /* Ptr to open files structure. (PFDL) */
struct pstats *p_stats; /* Accounting/statistics (PL). */
struct plimit *p_limit; /* Process limits.(PL) */
struct sigacts *p_sigacts; /* Signal actions, state (PL) */
lck_spin_t p_slock; /* spin lock for itimer/profil protection */
int p_siglist; /* signals captured back from threads */
unsigned int p_flag; /* P_* flags. (atomic bit ops) */
unsigned int p_lflag; /* local flags (PL) */
unsigned int p_listflag; /* list flags (LL) */
unsigned int p_ladvflag; /* local adv flags (atomic) */
int p_refcount; /* number of outstanding users(LL) */
int p_childrencnt; /* children holding ref on parent (LL) */
int p_parentref; /* children lookup ref on parent (LL) */
pid_t p_oppid; /* Save parent pid during ptrace. XXX */
u_int p_xstat; /* Exit status for wait; also stop signal. */
#ifdef _PROC_HAS_SCHEDINFO_
/* may need cleanup, not used */
u_int p_estcpu; /* Time averaged value of p_cpticks.(used by aio and proc_comapre) */
fixpt_t p_pctcpu; /* %cpu for this process during p_swtime (used by aio)*/
u_int p_slptime; /* used by proc_compare */
#endif /* _PROC_HAS_SCHEDINFO_ */
struct itimerval p_realtimer; /* Alarm timer. (PSL) */
struct timeval p_rtime; /* Real time.(PSL) */
struct itimerval p_vtimer_user; /* Virtual timers.(PSL) */
struct itimerval p_vtimer_prof; /* (PSL) */
struct timeval p_rlim_cpu; /* Remaining rlim cpu value.(PSL) */
int p_debugger; /* NU 1: can exec set-bit programs if suser */
boolean_t sigwait; /* indication to suspend (PL) */
void *sigwait_thread; /* 'thread' holding sigwait(PL) */
void *exit_thread; /* Which thread is exiting(PL) */
void * p_vforkact; /* activation running this vfork proc)(static) */
int p_vforkcnt; /* number of outstanding vforks(PL) */
int p_fpdrainwait; /* (PFDL) */
/* Following fields are info from SIGCHLD (PL) */
pid_t si_pid; /* (PL) */
u_int si_status; /* (PL) */
u_int si_code; /* (PL) */
uid_t si_uid; /* (PL) */
void * vm_shm; /* (SYSV SHM Lock) for sysV shared memory */
#if CONFIG_DTRACE
user_addr_t p_dtrace_argv; /* (write once, read only after that) */
user_addr_t p_dtrace_envp; /* (write once, read only after that) */
lck_mtx_t p_dtrace_sprlock; /* sun proc lock emulation */
uint8_t p_dtrace_stop; /* indicates a DTrace-desired stop */
int p_dtrace_probes; /* (PL) are there probes for this proc? */
u_int p_dtrace_count; /* (sprlock) number of DTrace tracepoints */
struct dtrace_ptss_page* p_dtrace_ptss_pages; /* (sprlock) list of user ptss pages */
struct dtrace_ptss_page_entry* p_dtrace_ptss_free_list; /* (atomic) list of individual ptss entries */
struct dtrace_helpers* p_dtrace_helpers; /* (dtrace_lock) DTrace per-proc private */
struct dof_ioctl_data* p_dtrace_lazy_dofs; /* (sprlock) unloaded dof_helper_t's */
#endif /* CONFIG_DTRACE */
/* XXXXXXXXXXXXX BCOPY'ed on fork XXXXXXXXXXXXXXXX */
/* The following fields are all copied upon creation in fork. */
#define p_startcopy p_argslen
u_int p_argslen; /* Length of process arguments. */
int p_argc; /* saved argc for sysctl_procargs() */
user_addr_t user_stack; /* where user stack was allocated */
struct vnode * XNU_PTRAUTH_SIGNED_PTR("proc.p_textvp") p_textvp; /* Vnode of executable. */
off_t p_textoff; /* offset in executable vnode */
sigset_t p_sigmask; /* DEPRECATED */
sigset_t p_sigignore; /* Signals being ignored. (PL) */
sigset_t p_sigcatch; /* Signals being caught by user.(PL) */
u_char p_priority; /* (NU) Process priority. */
u_char p_resv0; /* (NU) User-priority based on p_cpu and p_nice. */
char p_nice; /* Process "nice" value.(PL) */
u_char p_resv1; /* (NU) User-priority based on p_cpu and p_nice. */
// types currently in sys/param.h
command_t p_comm;
proc_name_t p_name; /* can be changed by the process */
uint8_t p_xhighbits; /* Stores the top byte of exit status to avoid truncation*/
pid_t p_contproc; /* last PID to send us a SIGCONT (PL) */
struct pgrp * XNU_PTRAUTH_SIGNED_PTR("proc.p_pgrp") p_pgrp; /* Pointer to process group. (LL) */
uint32_t p_csflags; /* flags for codesign (PL) */
uint32_t p_pcaction; /* action for process control on starvation */
uint8_t p_uuid[16]; /* from LC_UUID load command */
/*
* CPU type and subtype of binary slice executed in
* this process. Protected by proc lock.
*/
cpu_type_t p_cputype;
cpu_subtype_t p_cpusubtype;
uint8_t *syscall_filter_mask; /* syscall filter bitmask (length: nsysent bits) */
uint32_t p_platform;
uint32_t p_min_sdk;
uint32_t p_sdk;
/* End area that is copied on creation. */
/* XXXXXXXXXXXXX End of BCOPY'ed on fork (AIOLOCK)XXXXXXXXXXXXXXXX */
#define p_endcopy p_aio_total_count
int p_aio_total_count; /* all allocated AIO requests for this proc */
TAILQ_HEAD(, aio_workq_entry ) p_aio_activeq; /* active async IO requests */
TAILQ_HEAD(, aio_workq_entry ) p_aio_doneq; /* completed async IO requests */
struct klist p_klist; /* knote list (PL ?)*/
struct rusage_superset *p_ru; /* Exit information. (PL) */
thread_t p_signalholder;
thread_t p_transholder;
int p_sigwaitcnt;
/* DEPRECATE following field */
u_short p_acflag; /* Accounting flags. */
volatile u_short p_vfs_iopolicy; /* VFS iopolicy flags. (atomic bit ops) */
user_addr_t p_threadstart; /* pthread start fn */
user_addr_t p_wqthread; /* pthread workqueue fn */
int p_pthsize; /* pthread size */
uint32_t p_pth_tsd_offset; /* offset from pthread_t to TSD for new threads */
user_addr_t p_stack_addr_hint; /* stack allocation hint for wq threads */
struct workqueue *_Atomic p_wqptr; /* workq ptr */
struct timeval p_start; /* starting time */
void * p_rcall;
int p_ractive;
int p_idversion; /* version of process identity */
void * p_pthhash; /* pthread waitqueue hash */
volatile uint64_t was_throttled __attribute__((aligned(8))); /* Counter for number of throttled I/Os */
volatile uint64_t did_throttle __attribute__((aligned(8))); /* Counter for number of I/Os this proc throttled */
#if DIAGNOSTIC
unsigned int p_fdlock_pc[4];
unsigned int p_fdunlock_pc[4];
#if SIGNAL_DEBUG
unsigned int lockpc[8];
unsigned int unlockpc[8];
#endif /* SIGNAL_DEBUG */
#endif /* DIAGNOSTIC */
uint64_t p_dispatchqueue_offset;
uint64_t p_dispatchqueue_serialno_offset;
uint64_t p_dispatchqueue_label_offset;
uint64_t p_return_to_kernel_offset;
uint64_t p_mach_thread_self_offset;
#if VM_PRESSURE_EVENTS
struct timeval vm_pressure_last_notify_tstamp;
#endif
#if CONFIG_MEMORYSTATUS
/* Fields protected by proc list lock */
TAILQ_ENTRY(proc) p_memstat_list; /* priority bucket link */
uint32_t p_memstat_state; /* state. Also used as a wakeup channel when the memstat's LOCKED bit changes */
int32_t p_memstat_effectivepriority; /* priority after transaction state accounted for */
int32_t p_memstat_requestedpriority; /* active priority */
int32_t p_memstat_assertionpriority; /* assertion driven priority */
uint32_t p_memstat_dirty; /* dirty state */
uint64_t p_memstat_userdata; /* user state */
uint64_t p_memstat_idledeadline; /* time at which process became clean */
uint64_t p_memstat_idle_start; /* abstime process transitions into the idle band */
uint64_t p_memstat_idle_delta; /* abstime delta spent in idle band */
int32_t p_memstat_memlimit; /* cached memory limit, toggles between active and inactive limits */
int32_t p_memstat_memlimit_active; /* memory limit enforced when process is in active jetsam state */
int32_t p_memstat_memlimit_inactive; /* memory limit enforced when process is in inactive jetsam state */
int32_t p_memstat_relaunch_flags; /* flags indicating relaunch behavior for the process */
#if CONFIG_FREEZE
uint32_t p_memstat_freeze_sharedanon_pages; /* shared pages left behind after freeze */
uint32_t p_memstat_frozen_count;
uint32_t p_memstat_thaw_count;
#endif /* CONFIG_FREEZE */
#endif /* CONFIG_MEMORYSTATUS */
/* cached proc-specific data required for corpse inspection */
pid_t p_responsible_pid; /* pid resonsible for this process */
_Atomic uint32_t p_user_faults; /* count the number of user faults generated */
uint32_t p_memlimit_increase; /* byte increase for memory limit for dyld SPI rdar://problem/49950264, structure packing 32-bit and 64-bit */
struct os_reason *p_exit_reason;
#if CONFIG_PROC_UDATA_STORAGE
uint64_t p_user_data; /* general-purpose storage for userland-provided data */
#endif /* CONFIG_PROC_UDATA_STORAGE */
char * p_subsystem_root_path;
lck_rw_t p_dirs_lock; /* keeps fd_cdir and fd_rdir stable across a lookup */
pid_t p_sessionid;
};