/* $OpenBSD: sys_process.c,v 1.89 2021/12/07 04:19:24 guenther Exp $ */ /* $NetBSD: sys_process.c,v 1.55 1996/05/15 06:17:47 tls Exp $ */ /*- * Copyright (c) 1994 Christopher G. Demetriou. All rights reserved. * Copyright (c) 1982, 1986, 1989, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * from: @(#)sys_process.c 8.1 (Berkeley) 6/10/93 */ /* * References: * (1) Bach's "The Design of the UNIX Operating System", * (2) sys/miscfs/procfs from UCB's 4.4BSD-Lite distribution, * (3) the "4.4BSD Programmer's Reference Manual" published * by USENIX and O'Reilly & Associates. * The 4.4BSD PRM does a reasonably good job of documenting what the various * ptrace() requests should actually do, and its text is quoted several times * in this file. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef PTRACE static inline int process_checktracestate(struct process *_curpr, struct process *_tr, struct proc *_t); static inline struct process *process_tprfind(pid_t _tpid, struct proc **_tp); int ptrace_ctrl(struct proc *, int, pid_t, caddr_t, int); int ptrace_ustate(struct proc *, int, pid_t, void *, int, register_t *); int ptrace_kstate(struct proc *, int, pid_t, void *); int process_auxv_offset(struct proc *, struct process *, struct uio *); int global_ptrace; /* permit tracing of not children */ /* * Process debugging system call. */ int sys_ptrace(struct proc *p, void *v, register_t *retval) { struct sys_ptrace_args /* { syscallarg(int) req; syscallarg(pid_t) pid; syscallarg(caddr_t) addr; syscallarg(int) data; } */ *uap = v; int req = SCARG(uap, req); pid_t pid = SCARG(uap, pid); caddr_t uaddr = SCARG(uap, addr); /* userspace */ void *kaddr = NULL; /* kernelspace */ int data = SCARG(uap, data); union { struct ptrace_thread_state u_pts; struct ptrace_io_desc u_piod; struct ptrace_event u_pe; struct ptrace_state u_ps; register_t u_wcookie; } u; int size = 0; enum { NONE, IN, IN_ALLOC, OUT, OUT_ALLOC, IN_OUT } mode; int kstate = 0; int error; *retval = 0; /* Figure out what sort of copyin/out operations we'll do */ switch (req) { case PT_TRACE_ME: case PT_CONTINUE: case PT_KILL: case PT_ATTACH: case PT_DETACH: #ifdef PT_STEP case PT_STEP: #endif /* control operations do no copyin/out; dispatch directly */ return ptrace_ctrl(p, req, pid, uaddr, data); case PT_READ_I: case PT_READ_D: case PT_WRITE_I: case PT_WRITE_D: mode = NONE; break; case PT_IO: mode = IN_OUT; size = sizeof u.u_piod; data = size; /* suppress the data == size check */ break; case PT_GET_THREAD_FIRST: mode = OUT; size = sizeof u.u_pts; kstate = 1; break; case PT_GET_THREAD_NEXT: mode = IN_OUT; size = sizeof u.u_pts; kstate = 1; break; case PT_GET_EVENT_MASK: mode = OUT; size = sizeof u.u_pe; kstate = 1; break; case PT_SET_EVENT_MASK: mode = IN; size = sizeof u.u_pe; kstate = 1; break; case PT_GET_PROCESS_STATE: mode = OUT; size = sizeof u.u_ps; kstate = 1; break; case PT_GETREGS: mode = OUT_ALLOC; size = sizeof(struct reg); break; case PT_SETREGS: mode = IN_ALLOC; size = sizeof(struct reg); break; #ifdef PT_GETFPREGS case PT_GETFPREGS: mode = OUT_ALLOC; size = sizeof(struct fpreg); break; #endif #ifdef PT_SETFPREGS case PT_SETFPREGS: mode = IN_ALLOC; size = sizeof(struct fpreg); break; #endif #ifdef PT_GETXMMREGS case PT_GETXMMREGS: mode = OUT_ALLOC; size = sizeof(struct xmmregs); break; #endif #ifdef PT_SETXMMREGS case PT_SETXMMREGS: mode = IN_ALLOC; size = sizeof(struct xmmregs); break; #endif #ifdef PT_WCOOKIE case PT_WCOOKIE: mode = OUT; size = sizeof u.u_wcookie; data = size; /* suppress the data == size check */ break; #endif default: return EINVAL; } /* Now do any copyin()s and allocations in a consistent manner */ switch (mode) { case NONE: kaddr = uaddr; break; case IN: case IN_OUT: case OUT: KASSERT(size <= sizeof u); if (data != size) return EINVAL; if (mode == OUT) memset(&u, 0, size); else { /* IN or IN_OUT */ if ((error = copyin(uaddr, &u, size))) return error; } kaddr = &u; break; case IN_ALLOC: kaddr = malloc(size, M_TEMP, M_WAITOK); if ((error = copyin(uaddr, kaddr, size))) { free(kaddr, M_TEMP, size); return error; } break; case OUT_ALLOC: kaddr = malloc(size, M_TEMP, M_WAITOK | M_ZERO); break; } if (kstate) error = ptrace_kstate(p, req, pid, kaddr); else error = ptrace_ustate(p, req, pid, kaddr, data, retval); /* Do any copyout()s and frees */ if (error == 0) { switch (mode) { case NONE: case IN: case IN_ALLOC: break; case IN_OUT: case OUT: error = copyout(&u, uaddr, size); if (req == PT_IO) { /* historically, errors here are ignored */ error = 0; } break; case OUT_ALLOC: error = copyout(kaddr, uaddr, size); break; } } if (mode == IN_ALLOC || mode == OUT_ALLOC) free(kaddr, M_TEMP, size); return error; } /* * ptrace control requests: attach, detach, continue, kill, single-step, etc */ int ptrace_ctrl(struct proc *p, int req, pid_t pid, caddr_t addr, int data) { struct proc *t; /* target thread */ struct process *tr; /* target process */ int error = 0; int s; switch (req) { case PT_TRACE_ME: /* Just set the trace flag. */ tr = p->p_p; if (ISSET(tr->ps_flags, PS_TRACED)) return EBUSY; atomic_setbits_int(&tr->ps_flags, PS_TRACED); tr->ps_oppid = tr->ps_pptr->ps_pid; if (tr->ps_ptstat == NULL) tr->ps_ptstat = malloc(sizeof(*tr->ps_ptstat), M_SUBPROC, M_WAITOK); memset(tr->ps_ptstat, 0, sizeof(*tr->ps_ptstat)); return 0; /* calls that only operate on the PID */ case PT_KILL: case PT_ATTACH: case PT_DETACH: /* Find the process we're supposed to be operating on. */ if ((tr = prfind(pid)) == NULL) { error = ESRCH; goto fail; } t = TAILQ_FIRST(&tr->ps_threads); break; /* calls that accept a PID or a thread ID */ case PT_CONTINUE: #ifdef PT_STEP case PT_STEP: #endif if ((tr = process_tprfind(pid, &t)) == NULL) { error = ESRCH; goto fail; } break; } /* Check permissions/state */ if (req != PT_ATTACH) { /* Check that the data is a valid signal number or zero. */ if (req != PT_KILL && (data < 0 || data >= NSIG)) { error = EINVAL; goto fail; } /* Most operations require the target to already be traced */ if ((error = process_checktracestate(p->p_p, tr, t))) goto fail; /* Do single-step fixup if needed. */ FIX_SSTEP(t); } else { /* * PT_ATTACH is the opposite; you can't attach to a process if: * (1) it's the process that's doing the attaching, */ if (tr == p->p_p) { error = EINVAL; goto fail; } /* * (2) it's a system process */ if (ISSET(tr->ps_flags, PS_SYSTEM)) { error = EPERM; goto fail; } /* * (3) it's already being traced, or */ if (ISSET(tr->ps_flags, PS_TRACED)) { error = EBUSY; goto fail; } /* * (4) it's in the middle of execve(2) */ if (ISSET(tr->ps_flags, PS_INEXEC)) { error = EAGAIN; goto fail; } /* * (5) it's not owned by you, or the last exec * gave us setuid/setgid privs (unless * you're root), or... * * [Note: once PS_SUGID or PS_SUGIDEXEC gets set in * execve(), they stay set until the process does * another execve(). Hence this prevents a setuid * process which revokes its special privileges using * setuid() from being traced. This is good security.] */ if ((tr->ps_ucred->cr_ruid != p->p_ucred->cr_ruid || ISSET(tr->ps_flags, PS_SUGIDEXEC | PS_SUGID)) && (error = suser(p)) != 0) goto fail; /* * (5.5) it's not a child of the tracing process. */ if (global_ptrace == 0 && !inferior(tr, p->p_p) && (error = suser(p)) != 0) goto fail; /* * (6) ...it's init, which controls the security level * of the entire system, and the system was not * compiled with permanently insecure mode turned * on. */ if ((tr->ps_pid == 1) && (securelevel > -1)) { error = EPERM; goto fail; } /* * (7) it's an ancestor of the current process and * not init (because that would create a loop in * the process graph). */ if (tr->ps_pid != 1 && inferior(p->p_p, tr)) { error = EINVAL; goto fail; } } switch (req) { #ifdef PT_STEP case PT_STEP: /* * From the 4.4BSD PRM: * "Execution continues as in request PT_CONTINUE; however * as soon as possible after execution of at least one * instruction, execution stops again. [ ... ]" */ #endif case PT_CONTINUE: /* * From the 4.4BSD PRM: * "The data argument is taken as a signal number and the * child's execution continues at location addr as if it * incurred that signal. Normally the signal number will * be either 0 to indicate that the signal that caused the * stop should be ignored, or that value fetched out of * the process's image indicating which signal caused * the stop. If addr is (int *)1 then execution continues * from where it stopped." */ if (pid < THREAD_PID_OFFSET && tr->ps_single) t = tr->ps_single; /* If the address parameter is not (int *)1, set the pc. */ if ((int *)addr != (int *)1) if ((error = process_set_pc(t, addr)) != 0) goto fail; #ifdef PT_STEP /* * Arrange for a single-step, if that's requested and possible. */ error = process_sstep(t, req == PT_STEP); if (error) goto fail; #endif goto sendsig; case PT_DETACH: /* * From the 4.4BSD PRM: * "The data argument is taken as a signal number and the * child's execution continues at location addr as if it * incurred that signal. Normally the signal number will * be either 0 to indicate that the signal that caused the * stop should be ignored, or that value fetched out of * the process's image indicating which signal caused * the stop. If addr is (int *)1 then execution continues * from where it stopped." */ if (pid < THREAD_PID_OFFSET && tr->ps_single) t = tr->ps_single; #ifdef PT_STEP /* * Stop single stepping. */ error = process_sstep(t, 0); if (error) goto fail; #endif process_untrace(tr); atomic_clearbits_int(&tr->ps_flags, PS_WAITED); sendsig: memset(tr->ps_ptstat, 0, sizeof(*tr->ps_ptstat)); /* Finally, deliver the requested signal (or none). */ if (t->p_stat == SSTOP) { tr->ps_xsig = data; SCHED_LOCK(s); setrunnable(t); SCHED_UNLOCK(s); } else { if (data != 0) psignal(t, data); } break; case PT_KILL: if (pid < THREAD_PID_OFFSET && tr->ps_single) t = tr->ps_single; /* just send the process a KILL signal. */ data = SIGKILL; goto sendsig; /* in PT_CONTINUE, above. */ case PT_ATTACH: /* * As was done in procfs: * Go ahead and set the trace flag. * Save the old parent (it's reset in * _DETACH, and also in kern_exit.c:wait4() * Reparent the process so that the tracing * proc gets to see all the action. * Stop the target. */ atomic_setbits_int(&tr->ps_flags, PS_TRACED); tr->ps_oppid = tr->ps_pptr->ps_pid; process_reparent(tr, p->p_p); if (tr->ps_ptstat == NULL) tr->ps_ptstat = malloc(sizeof(*tr->ps_ptstat), M_SUBPROC, M_WAITOK); data = SIGSTOP; goto sendsig; default: KASSERTMSG(0, "%s: unhandled request %d", __func__, req); break; } fail: return error; } /* * ptrace kernel-state requests: thread list, event mask, process state */ int ptrace_kstate(struct proc *p, int req, pid_t pid, void *addr) { struct process *tr; /* target process */ struct ptrace_event *pe = addr; int error; KASSERT((p->p_flag & P_SYSTEM) == 0); /* Find the process we're supposed to be operating on. */ if ((tr = prfind(pid)) == NULL) return ESRCH; if ((error = process_checktracestate(p->p_p, tr, NULL))) return error; switch (req) { case PT_GET_THREAD_FIRST: case PT_GET_THREAD_NEXT: { struct ptrace_thread_state *pts = addr; struct proc *t; if (req == PT_GET_THREAD_NEXT) { t = tfind(pts->pts_tid - THREAD_PID_OFFSET); if (t == NULL || ISSET(t->p_flag, P_WEXIT)) return ESRCH; if (t->p_p != tr) return EINVAL; t = TAILQ_NEXT(t, p_thr_link); } else { t = TAILQ_FIRST(&tr->ps_threads); } if (t == NULL) pts->pts_tid = -1; else pts->pts_tid = t->p_tid + THREAD_PID_OFFSET; return 0; } } switch (req) { case PT_GET_EVENT_MASK: pe->pe_set_event = tr->ps_ptmask; break; case PT_SET_EVENT_MASK: tr->ps_ptmask = pe->pe_set_event; break; case PT_GET_PROCESS_STATE: if (tr->ps_single) tr->ps_ptstat->pe_tid = tr->ps_single->p_tid + THREAD_PID_OFFSET; memcpy(addr, tr->ps_ptstat, sizeof *tr->ps_ptstat); break; default: KASSERTMSG(0, "%s: unhandled request %d", __func__, req); break; } return 0; } /* * ptrace user-state requests: memory access, registers, stack cookie */ int ptrace_ustate(struct proc *p, int req, pid_t pid, void *addr, int data, register_t *retval) { struct proc *t; /* target thread */ struct process *tr; /* target process */ struct uio uio; struct iovec iov; int error, write; int temp = 0; KASSERT((p->p_flag & P_SYSTEM) == 0); /* Accept either PID or TID */ if ((tr = process_tprfind(pid, &t)) == NULL) return ESRCH; if ((error = process_checktracestate(p->p_p, tr, t))) return error; FIX_SSTEP(t); /* Now do the operation. */ write = 0; if ((error = process_checkioperm(p, tr)) != 0) return error; switch (req) { case PT_WRITE_I: /* XXX no separate I and D spaces */ case PT_WRITE_D: write = 1; temp = data; case PT_READ_I: /* XXX no separate I and D spaces */ case PT_READ_D: /* write = 0 done above. */ iov.iov_base = (caddr_t)&temp; iov.iov_len = sizeof(int); uio.uio_iov = &iov; uio.uio_iovcnt = 1; uio.uio_offset = (off_t)(vaddr_t)addr; uio.uio_resid = sizeof(int); uio.uio_segflg = UIO_SYSSPACE; uio.uio_rw = write ? UIO_WRITE : UIO_READ; uio.uio_procp = p; error = process_domem(p, tr, &uio, write ? PT_WRITE_I : PT_READ_I); if (write == 0) *retval = temp; return error; case PT_IO: { struct ptrace_io_desc *piod = addr; iov.iov_base = piod->piod_addr; iov.iov_len = piod->piod_len; uio.uio_iov = &iov; uio.uio_iovcnt = 1; uio.uio_offset = (off_t)(vaddr_t)piod->piod_offs; uio.uio_resid = piod->piod_len; uio.uio_segflg = UIO_USERSPACE; uio.uio_procp = p; switch (piod->piod_op) { case PIOD_READ_I: req = PT_READ_I; uio.uio_rw = UIO_READ; break; case PIOD_READ_D: req = PT_READ_D; uio.uio_rw = UIO_READ; break; case PIOD_WRITE_I: req = PT_WRITE_I; uio.uio_rw = UIO_WRITE; break; case PIOD_WRITE_D: req = PT_WRITE_D; uio.uio_rw = UIO_WRITE; break; case PIOD_READ_AUXV: req = PT_READ_D; uio.uio_rw = UIO_READ; temp = ELF_AUX_WORDS * sizeof(char *); if (uio.uio_offset > temp) return EIO; if (uio.uio_resid > temp - uio.uio_offset) uio.uio_resid = temp - uio.uio_offset; piod->piod_len = iov.iov_len = uio.uio_resid; error = process_auxv_offset(p, tr, &uio); if (error) return error; break; default: return EINVAL; } error = process_domem(p, tr, &uio, req); piod->piod_len -= uio.uio_resid; return error; } case PT_SETREGS: return process_write_regs(t, addr); case PT_GETREGS: return process_read_regs(t, addr); #ifdef PT_SETFPREGS case PT_SETFPREGS: return process_write_fpregs(t, addr); #endif #ifdef PT_SETFPREGS case PT_GETFPREGS: return process_read_fpregs(t, addr); #endif #ifdef PT_SETXMMREGS case PT_SETXMMREGS: return process_write_xmmregs(t, addr); #endif #ifdef PT_SETXMMREGS case PT_GETXMMREGS: return process_read_xmmregs(t, addr); #endif #ifdef PT_WCOOKIE case PT_WCOOKIE: *(register_t *)addr = process_get_wcookie(t); return 0; #endif default: KASSERTMSG(0, "%s: unhandled request %d", __func__, req); break; } return 0; } /* * Helper for doing "it could be a PID or TID" lookup. On failure * returns NULL; on success returns the selected process and sets *tp * to an appropriate thread in that process. */ static inline struct process * process_tprfind(pid_t tpid, struct proc **tp) { if (tpid > THREAD_PID_OFFSET) { struct proc *t = tfind(tpid - THREAD_PID_OFFSET); if (t == NULL) return NULL; *tp = t; return t->p_p; } else { struct process *tr = prfind(tpid); if (tr == NULL) return NULL; *tp = TAILQ_FIRST(&tr->ps_threads); return tr; } } /* * Check whether 'tr' is currently traced by 'curpr' and in a state * to be manipulated. If 't' is supplied then it must be stopped and * waited for. */ static inline int process_checktracestate(struct process *curpr, struct process *tr, struct proc *t) { /* * You can't do what you want to the process if: * (1) It's not being traced at all, */ if (!ISSET(tr->ps_flags, PS_TRACED)) return EPERM; /* * (2) it's not being traced by _you_, or */ if (tr->ps_pptr != curpr) return EBUSY; /* * (3) it's in the middle of execve(2) */ if (ISSET(tr->ps_flags, PS_INEXEC)) return EAGAIN; /* * (4) if a thread was specified and it's not currently stopped. */ if (t != NULL && (t->p_stat != SSTOP || !ISSET(tr->ps_flags, PS_WAITED))) return EBUSY; return 0; } /* * Check if a process is allowed to fiddle with the memory of another. * * p = tracer * tr = tracee * * 1. You can't attach to a process not owned by you or one that has raised * its privileges. * 1a. ...unless you are root. * * 2. init is always off-limits because it can control the securelevel. * 2a. ...unless securelevel is permanently set to insecure. * * 3. Processes that are in the process of doing an exec() are always * off-limits because of the can of worms they are. Just wait a * second. */ int process_checkioperm(struct proc *p, struct process *tr) { int error; if ((tr->ps_ucred->cr_ruid != p->p_ucred->cr_ruid || ISSET(tr->ps_flags, PS_SUGIDEXEC | PS_SUGID)) && (error = suser(p)) != 0) return (error); if ((tr->ps_pid == 1) && (securelevel > -1)) return (EPERM); if (ISSET(tr->ps_flags, PS_INEXEC)) return (EAGAIN); return (0); } int process_domem(struct proc *curp, struct process *tr, struct uio *uio, int req) { struct vmspace *vm; int error; vaddr_t addr; vsize_t len; len = uio->uio_resid; if (len == 0) return 0; if ((error = process_checkioperm(curp, tr)) != 0) return error; vm = tr->ps_vmspace; if ((tr->ps_flags & PS_EXITING) || (vm->vm_refcnt < 1)) return EFAULT; addr = uio->uio_offset; uvmspace_addref(vm); error = uvm_io(&vm->vm_map, uio, (uio->uio_rw == UIO_WRITE) ? UVM_IO_FIXPROT : 0); uvmspace_free(vm); if (error == 0 && req == PT_WRITE_I) pmap_proc_iflush(tr, addr, len); return error; } int process_auxv_offset(struct proc *curp, struct process *tr, struct uio *uiop) { struct vmspace *vm; struct ps_strings pss; struct iovec iov; struct uio uio; int error; iov.iov_base = &pss; iov.iov_len = sizeof(pss); uio.uio_iov = &iov; uio.uio_iovcnt = 1; uio.uio_offset = (off_t)tr->ps_strings; uio.uio_resid = sizeof(pss); uio.uio_segflg = UIO_SYSSPACE; uio.uio_rw = UIO_READ; uio.uio_procp = curp; vm = tr->ps_vmspace; if ((tr->ps_flags & PS_EXITING) || (vm->vm_refcnt < 1)) return EFAULT; uvmspace_addref(vm); error = uvm_io(&vm->vm_map, &uio, 0); uvmspace_free(vm); if (error != 0) return error; if (pss.ps_envstr == NULL) return EIO; uiop->uio_offset += (off_t)(vaddr_t)(pss.ps_envstr + pss.ps_nenvstr + 1); #ifdef MACHINE_STACK_GROWS_UP if (uiop->uio_offset < (off_t)tr->ps_strings) return EIO; #else if (uiop->uio_offset > (off_t)tr->ps_strings) return EIO; if ((uiop->uio_offset + uiop->uio_resid) > (off_t)tr->ps_strings) uiop->uio_resid = (off_t)tr->ps_strings - uiop->uio_offset; #endif return 0; } #endif