The T_DUMPCORE implementation was not only broken - it would currently produce a coredump of the tracer process rather than the traced process - but also deeply flawed, and fixing it would require serious alteration of PM's internal state machine. It should be possible to implement the same functionality in userland, and that is now the suggested way forward. For now, also remove the (identical) utilities using T_DUMPCORE: dumpcore(1) and gcore(1). Change-Id: I1d51be19c739362b8a5833de949b76382a1edbcc
268 lines
7.7 KiB
C
268 lines
7.7 KiB
C
/* This file handles the process manager's part of debugging, using the
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* ptrace system call. Most of the commands are passed on to the system
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* task for completion.
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*
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* The debugging commands available are:
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* T_STOP stop the process
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* T_OK enable tracing by parent for this process
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* T_GETINS return value from instruction space
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* T_GETDATA return value from data space
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* T_GETUSER return value from user process table
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* T_SETINS set value in instruction space
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* T_SETDATA set value in data space
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* T_SETUSER set value in user process table
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* T_RESUME resume execution
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* T_EXIT exit
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* T_STEP set trace bit
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* T_SYSCALL trace system call
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* T_ATTACH attach to an existing process
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* T_DETACH detach from a traced process
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* T_SETOPT set trace options
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* T_GETRANGE get range of values
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* T_SETRANGE set range of values
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*
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* The T_OK, T_ATTACH, T_EXIT, and T_SETOPT commands are handled here, and the
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* T_RESUME, T_STEP, T_SYSCALL, and T_DETACH commands are partially handled
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* here and completed by the system task. The rest are handled entirely by the
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* system task.
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*/
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#include "pm.h"
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#include <minix/com.h>
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#include <sys/ptrace.h>
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#include <signal.h>
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#include "mproc.h"
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#include "param.h"
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/*===========================================================================*
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* do_trace *
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*===========================================================================*/
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int do_trace()
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{
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register struct mproc *child;
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struct ptrace_range pr;
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int i, r, req;
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message m;
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req = m_in.request;
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/* The T_OK call is made by the child fork of the debugger before it execs
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* the process to be traced. The T_ATTACH call is made by the debugger itself
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* to attach to an existing process.
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*/
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switch (req) {
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case T_OK: /* enable tracing by parent for this proc */
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if (mp->mp_tracer != NO_TRACER) return(EBUSY);
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mp->mp_tracer = mp->mp_parent;
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mp->mp_reply.reply_trace = 0;
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return(OK);
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case T_ATTACH: /* attach to an existing process */
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if ((child = find_proc(m_in.pid)) == NULL) return(ESRCH);
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if (child->mp_flags & EXITING) return(ESRCH);
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/* For non-root processes, user and group ID must match. */
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if (mp->mp_effuid != SUPER_USER &&
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(mp->mp_effuid != child->mp_effuid ||
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mp->mp_effgid != child->mp_effgid ||
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child->mp_effuid != child->mp_realuid ||
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child->mp_effgid != child->mp_realgid)) return(EPERM);
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/* Only root may trace system servers. */
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if (mp->mp_effuid != SUPER_USER && (child->mp_flags & PRIV_PROC))
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return(EPERM);
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/* System servers may not trace anyone. They can use sys_trace(). */
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if (mp->mp_flags & PRIV_PROC) return(EPERM);
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/* Can't trace self, PM or VM. */
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if (child == mp || child->mp_endpoint == PM_PROC_NR ||
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child->mp_endpoint == VM_PROC_NR) return(EPERM);
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/* Can't trace a process that is already being traced. */
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if (child->mp_tracer != NO_TRACER) return(EBUSY);
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child->mp_tracer = who_p;
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child->mp_trace_flags = TO_NOEXEC;
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sig_proc(child, SIGSTOP, TRUE /*trace*/, FALSE /* ksig */);
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mp->mp_reply.reply_trace = 0;
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return(OK);
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case T_STOP: /* stop the process */
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/* This call is not exposed to user programs, because its effect can be
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* achieved better by sending the traced process a signal with kill(2).
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*/
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return(EINVAL);
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case T_READB_INS: /* special hack for reading text segments */
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if (mp->mp_effuid != SUPER_USER) return(EPERM);
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if ((child = find_proc(m_in.pid)) == NULL) return(ESRCH);
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if (child->mp_flags & EXITING) return(ESRCH);
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r = sys_trace(req, child->mp_endpoint, m_in.PMTRACE_ADDR, &m_in.data);
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if (r != OK) return(r);
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mp->mp_reply.reply_trace = m_in.data;
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return(OK);
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case T_WRITEB_INS: /* special hack for patching text segments */
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if (mp->mp_effuid != SUPER_USER) return(EPERM);
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if ((child = find_proc(m_in.pid)) == NULL) return(ESRCH);
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if (child->mp_flags & EXITING) return(ESRCH);
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#if 0
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/* Should check for shared text */
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/* Make sure the text segment is not used as a source for shared
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* text.
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*/
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child->mp_ino = 0;
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child->mp_dev = 0;
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child->mp_ctime = 0;
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#endif
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r = sys_trace(req, child->mp_endpoint, m_in.PMTRACE_ADDR, &m_in.data);
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if (r != OK) return(r);
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mp->mp_reply.reply_trace = m_in.data;
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return(OK);
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}
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/* All the other calls are made by the tracing process to control execution
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* of the child. For all these calls, the child must be stopped.
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*/
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if ((child = find_proc(m_in.pid)) == NULL) return(ESRCH);
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if (child->mp_flags & EXITING) return(ESRCH);
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if (child->mp_tracer != who_p) return(ESRCH);
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if (!(child->mp_flags & STOPPED)) return(EBUSY);
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switch (req) {
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case T_EXIT: /* exit */
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child->mp_flags |= TRACE_EXIT;
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/* Defer the exit if the traced process has an VFS call pending. */
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if (child->mp_flags & VFS_CALL)
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child->mp_exitstatus = (int) m_in.data; /* save for later */
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else
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exit_proc(child, (int) m_in.data, FALSE /*dump_core*/);
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/* Do not reply to the caller until VFS has processed the exit
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* request.
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*/
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return(SUSPEND);
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case T_SETOPT: /* set trace options */
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child->mp_trace_flags = m_in.data;
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mp->mp_reply.reply_trace = 0;
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return(OK);
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case T_GETRANGE:
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case T_SETRANGE: /* get/set range of values */
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r = sys_datacopy(who_e, (vir_bytes) m_in.PMTRACE_ADDR,
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SELF, (vir_bytes) &pr, (phys_bytes) sizeof(pr));
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if (r != OK) return(r);
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if (pr.pr_space != TS_INS && pr.pr_space != TS_DATA) return(EINVAL);
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if (pr.pr_size == 0 || pr.pr_size > LONG_MAX) return(EINVAL);
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if (req == T_GETRANGE)
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r = sys_vircopy(child->mp_endpoint, (vir_bytes) pr.pr_addr,
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who_e, (vir_bytes) pr.pr_ptr,
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(phys_bytes) pr.pr_size);
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else
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r = sys_vircopy(who_e, (vir_bytes) pr.pr_ptr,
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child->mp_endpoint, (vir_bytes) pr.pr_addr,
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(phys_bytes) pr.pr_size);
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if (r != OK) return(r);
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mp->mp_reply.reply_trace = 0;
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return(OK);
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case T_DETACH: /* detach from traced process */
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if (m_in.data < 0 || m_in.data >= _NSIG) return(EINVAL);
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child->mp_tracer = NO_TRACER;
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/* Let all tracer-pending signals through the filter. */
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for (i = 1; i < _NSIG; i++) {
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if (sigismember(&child->mp_sigtrace, i)) {
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sigdelset(&child->mp_sigtrace, i);
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check_sig(child->mp_pid, i, FALSE /* ksig */);
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}
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}
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if (m_in.data > 0) { /* issue signal */
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sig_proc(child, (int) m_in.data, TRUE /*trace*/,
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FALSE /* ksig */);
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}
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/* Resume the child as if nothing ever happened. */
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child->mp_flags &= ~STOPPED;
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child->mp_trace_flags = 0;
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check_pending(child);
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break;
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case T_RESUME:
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case T_STEP:
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case T_SYSCALL: /* resume execution */
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if (m_in.data < 0 || m_in.data >= _NSIG) return(EINVAL);
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if (m_in.data > 0) { /* issue signal */
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sig_proc(child, (int) m_in.data, FALSE /*trace*/,
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FALSE /* ksig */);
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}
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/* If there are any other signals waiting to be delivered,
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* feign a successful resumption.
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*/
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for (i = 1; i < _NSIG; i++) {
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if (sigismember(&child->mp_sigtrace, i)) {
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mp->mp_reply.reply_trace = 0;
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return(OK);
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}
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}
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child->mp_flags &= ~STOPPED;
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check_pending(child);
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break;
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}
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r = sys_trace(req, child->mp_endpoint, m_in.PMTRACE_ADDR, &m_in.data);
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if (r != OK) return(r);
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mp->mp_reply.reply_trace = m_in.data;
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return(OK);
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}
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/*===========================================================================*
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* stop_proc *
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*===========================================================================*/
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void stop_proc(rmp, signo)
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register struct mproc *rmp;
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int signo;
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{
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/* A traced process got a signal so stop it. */
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register struct mproc *rpmp = mproc + rmp->mp_tracer;
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int r;
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r = sys_trace(T_STOP, rmp->mp_endpoint, 0L, (long *) 0);
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if (r != OK) panic("sys_trace failed: %d", r);
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rmp->mp_flags |= STOPPED;
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if (wait_test(rpmp, rmp)) {
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sigdelset(&rmp->mp_sigtrace, signo);
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rpmp->mp_flags &= ~WAITING; /* parent is no longer waiting */
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rpmp->mp_reply.reply_res2 = 0177 | (signo << 8);
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setreply(rmp->mp_tracer, rmp->mp_pid);
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}
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}
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