pcontrol.c

Sun Solaris 10 中的 DTrace 组件的源代码。请参看: http://www.sun.com/software/solaris/observability.jsp

		default:
			dprintf("Pgrab: failed to open %s: %s\n",
			    procname, strerror(errno));
			rc = G_STRANGE;
			break;
		}
		goto err;
	}
	P->asfd = fd;

	(void) strcpy(fname, "status");
	if ((fd = open(procname, O_RDONLY)) < 0 ||
	    (fd = dupfd(fd, 0)) < 0) {
		switch (errno) {
		case ENOENT:
			rc = G_NOPROC;
			break;
		default:
			dprintf("Pgrab: failed to open %s: %s\n",
			    procname, strerror(errno));
			rc = G_STRANGE;
			break;
		}
		goto err;
	}
	P->statfd = fd;

	if (!(flags & PGRAB_RDONLY)) {
		(void) strcpy(fname, "ctl");
		if ((fd = open(procname, O_WRONLY)) < 0 ||
		    (fd = dupfd(fd, 0)) < 0) {
			switch (errno) {
			case ENOENT:
				rc = G_NOPROC;
				break;
			default:
				dprintf("Pgrab: failed to open %s: %s\n",
				    procname, strerror(errno));
				rc = G_STRANGE;
				break;
			}
			goto err;
		}
		P->ctlfd = fd;
	}

	P->state = PS_RUN;
	P->pid = pid;

	/*
	 * We are now in the Window of Vulnerability (WoV).  The process may
	 * exec() a setuid/setgid or unreadable object file between the open()
	 * and the PCSTOP.  We will get EAGAIN in this case and must start over.
	 * As Pstopstatus will trigger the first read() from a /proc file,
	 * we also need to handle EOVERFLOW here when 32-bit as an indicator
	 * that this process is 64-bit.  Finally, if the process has become
	 * a zombie (PS_UNDEAD) while we were trying to grab it, just remain
	 * silent about this and pretend there was no process.
	 */
	if (Pstopstatus(P, PCNULL, 0) != 0) {
#ifndef _LP64
		if (errno == EOVERFLOW) {
			rc = G_LP64;
			goto err;
		}
#endif
		if (P->state == PS_LOST) {	/* WoV */
			(void) mutex_destroy(&P->proc_lock);
			goto again;
		}

		if (P->state == PS_UNDEAD)
			rc = G_NOPROC;
		else
			rc = G_STRANGE;

		goto err;
	}

	/*
	 * If the process is a system process, we can't control it even as root
	 */
	if (P->status.pr_flags & PR_ISSYS) {
		rc = G_SYS;
		goto err;
	}
#ifndef _LP64
	/*
	 * We must be a 64-bit process to deal with a 64-bit process
	 */
	if (P->status.pr_dmodel == PR_MODEL_LP64) {
		rc = G_LP64;
		goto err;
	}
#endif

	/*
	 * Remember the status for use by Prelease().
	 */
	P->orig_status = P->status;	/* structure copy */

	/*
	 * Before stopping the process, make sure we are not grabbing ourselves.
	 * If we are, make sure we are doing it PGRAB_RDONLY.
	 */
	if (pid == getpid()) {
		/*
		 * Verify that the process is really ourself:
		 * Set a magic number, read it through the
		 * /proc file and see if the results match.
		 */
		uint32_t magic1 = 0;
		uint32_t magic2 = 2;

		errno = 0;

		if (Pread(P, &magic2, sizeof (magic2), (uintptr_t)&magic1)
		    == sizeof (magic2) &&
		    magic2 == 0 &&
		    (magic1 = 0xfeedbeef) &&
		    Pread(P, &magic2, sizeof (magic2), (uintptr_t)&magic1)
		    == sizeof (magic2) &&
		    magic2 == 0xfeedbeef &&
		    !(flags & PGRAB_RDONLY)) {
			rc = G_SELF;
			goto err;
		}
	}

	/*
	 * If the process is already stopped or has been directed
	 * to stop via /proc, do not set run-on-last-close.
	 */
	if (!(P->status.pr_lwp.pr_flags & (PR_ISTOP|PR_DSTOP)) &&
	    !(flags & PGRAB_RDONLY)) {
		/*
		 * Mark the process run-on-last-close so
		 * it runs even if we die from SIGKILL.
		 */
		if (Psetflags(P, PR_RLC) != 0) {
			if (errno == EAGAIN) {	/* WoV */
				(void) mutex_destroy(&P->proc_lock);
				goto again;
			}
			if (errno == ENOENT)	/* No complaint about zombies */
				rc = G_ZOMB;
			else {
				dprintf("Pgrab: failed to set RLC\n");
				rc = G_STRANGE;
			}
			goto err;
		}
	}

	/*
	 * If a stop directive is pending and the process has not yet stopped,
	 * then synchronously wait for the stop directive to take effect.
	 * Limit the time spent waiting for the process to stop by iterating
	 * at most 10 times. The time-out of 20 ms corresponds to the time
	 * between sending the stop directive and the process actually stopped
	 * as measured by DTrace on a slow, busy system. If the process doesn't
	 * stop voluntarily, clear the PR_DSTOP flag so that the code below
	 * forces the process to stop.
	 */
	if (!(flags & PGRAB_RDONLY)) {
		int niter = 0;
		while ((P->status.pr_lwp.pr_flags & (PR_STOPPED|PR_DSTOP)) ==
		    PR_DSTOP && niter < 10 &&
		    Pstopstatus(P, PCTWSTOP, 20) != 0) {
			niter++;
			if (flags & PGRAB_NOSTOP)
				break;
		}
		if (niter == 10 && !(flags & PGRAB_NOSTOP)) {
			/* Try it harder down below */
			P->status.pr_lwp.pr_flags &= ~PR_DSTOP;
		}
	}

	/*
	 * If the process is not already stopped or directed to stop
	 * and PGRAB_NOSTOP was not specified, stop the process now.
	 */
	if (!(P->status.pr_lwp.pr_flags & (PR_ISTOP|PR_DSTOP)) &&
	    !(flags & PGRAB_NOSTOP)) {
		/*
		 * Stop the process, get its status and signal/syscall masks.
		 */
		if (((P->status.pr_lwp.pr_flags & PR_STOPPED) &&
		    Pstopstatus(P, PCDSTOP, 0) != 0) ||
		    Pstopstatus(P, PCSTOP, 2000) != 0) {
#ifndef _LP64
			if (errno == EOVERFLOW) {
				rc = G_LP64;
				goto err;
			}
#endif
			if (P->state == PS_LOST) {	/* WoV */
				(void) mutex_destroy(&P->proc_lock);
				goto again;
			}
			if ((errno != EINTR && errno != ERESTART) ||
			    (P->state != PS_STOP &&
			    !(P->status.pr_flags & PR_DSTOP))) {
				if (P->state != PS_RUN && errno != ENOENT) {
					dprintf("Pgrab: failed to PCSTOP\n");
					rc = G_STRANGE;
				} else {
					rc = G_ZOMB;
				}
				goto err;
			}
		}

		/*
		 * Process should now either be stopped via /proc or there
		 * should be an outstanding stop directive.
		 */
		if (!(P->status.pr_flags & (PR_ISTOP|PR_DSTOP))) {
			dprintf("Pgrab: process is not stopped\n");
			rc = G_STRANGE;
			goto err;
		}
#ifndef _LP64
		/*
		 * Test this again now because the 32-bit victim process may
		 * have exec'd a 64-bit process in the meantime.
		 */
		if (P->status.pr_dmodel == PR_MODEL_LP64) {
			rc = G_LP64;
			goto err;
		}
#endif
	}

	/*
	 * Cancel all tracing flags unless the PGRAB_RETAIN flag is set.
	 */
	if (!(flags & PGRAB_RETAIN)) {
		(void) Psysentry(P, 0, FALSE);
		(void) Psysexit(P, 0, FALSE);
		(void) Psignal(P, 0, FALSE);
		(void) Pfault(P, 0, FALSE);
		Psync(P);
	}

	*perr = 0;
	return (P);

err:
	Pfree(P);
	*perr = rc;
	return (NULL);
}

/*
 * Return a printable string corresponding to a Pgrab() error return.
 */
const char *
Pgrab_error(int error)
{
	const char *str;

	switch (error) {
	case G_NOPROC:
		str = "no such process";
		break;
	case G_NOCORE:
		str = "no such core file";
		break;
	case G_NOPROCORCORE:
		str = "no such process or core file";
		break;
	case G_NOEXEC:
		str = "cannot find executable file";
		break;
	case G_ZOMB:
		str = "zombie process";
		break;
	case G_PERM:
		str = "permission denied";
		break;
	case G_BUSY:
		str = "process is traced";
		break;
	case G_SYS:
		str = "system process";
		break;
	case G_SELF:
		str = "attempt to grab self";
		break;
	case G_INTR:
		str = "operation interrupted";
		break;
	case G_LP64:
		str = "program is _LP64, self is not";
		break;
	case G_FORMAT:
		str = "file is not an ELF core file";
		break;
	case G_ELF:
		str = "libelf error";
		break;
	case G_NOTE:
		str = "core file is corrupt or missing required data";
		break;
	case G_STRANGE:
		str = "unanticipated system error";
		break;
	case G_ISAINVAL:
		str = "wrong ELF machine type";
		break;
	case G_BADLWPS:
		str = "bad lwp specification";
		break;
	default:
		str = "unknown error";
		break;
	}

	return (str);
}

/*
 * Free a process control structure.
 * Close the file descriptors but don't do the Prelease logic.
 */
void
Pfree(struct ps_prochandle *P)
{
	uint_t i;

	if (P->core != NULL) {
		extern void __priv_free_info(void *);
		lwp_info_t *nlwp, *lwp = list_next(&P->core->core_lwp_head);

		for (i = 0; i < P->core->core_nlwp; i++, lwp = nlwp) {
			nlwp = list_next(lwp);
#ifdef __sparc
			if (lwp->lwp_gwins != NULL)
				free(lwp->lwp_gwins);
			if (lwp->lwp_xregs != NULL)
				free(lwp->lwp_xregs);
			if (lwp->lwp_asrs != NULL)
				free(lwp->lwp_asrs);
#endif
			free(lwp);
		}

		if (P->core->core_platform != NULL)
			free(P->core->core_platform);
		if (P->core->core_uts != NULL)
			free(P->core->core_uts);
		if (P->core->core_cred != NULL)
			free(P->core->core_cred);
		if (P->core->core_priv != NULL)
			free(P->core->core_priv);
		if (P->core->core_privinfo != NULL)
			__priv_free_info(P->core->core_privinfo);
		if (P->core->core_ppii != NULL)
			free(P->core->core_ppii);
		if (P->core->core_zonename != NULL)
			free(P->core->core_zonename);
#if defined(__i386) || defined(__amd64)
		if (P->core->core_ldt != NULL)
			free(P->core->core_ldt);
#endif

		free(P->core);
	}

	if (P->ucaddrs != NULL) {
		free(P->ucaddrs);
		P->ucaddrs = NULL;
		P->ucnelems = 0;
	}

	(void) mutex_lock(&P->proc_lock);
	if (P->hashtab != NULL) {
		struct ps_lwphandle *L;
		for (i = 0; i < HASHSIZE; i++) {
			while ((L = P->hashtab[i]) != NULL)
				Lfree_internal(P, L);
		}
		free(P->hashtab);
	}
	(void) mutex_unlock(&P->proc_lock);
	(void) mutex_destroy(&P->proc_lock);

	if (P->agentctlfd >= 0)
		(void) close(P->agentctlfd);
	if (P->agentstatfd >= 0)
		(void) close(P->agentstatfd);
	if (P->ctlfd >= 0)
		(void) close(P->ctlfd);
	if (P->asfd >= 0)
		(void) close(P->asfd);
	if (P->statfd >= 0)
		(void) close(P->statfd);
	Preset_maps(P);

	/* clear out the structure as a precaution against reuse */
	(void) memset(P, 0, sizeof (*P));
	P->ctlfd = -1;
	P->asfd = -1;
	P->statfd = -1;
	P->agentctlfd = -1;
	P->agentstatfd = -1;

	free(P);
}

/*
 * Return the state of the process, one of the PS_* values.
 */
int
Pstate(struct ps_prochandle *P)
{
	return (P->state);
}

/*
 * Return the open address space file descriptor for the process.
 * Clients must not close this file descriptor, not use it
 * after the process is freed.
 */
int
Pasfd(struct ps_prochandle *P)
{
	return (P->asfd);
}

/*
 * Return the open control file descriptor for the process.
 * Clients must not close this file descriptor, not use it
 * after the process is freed.
 */
int
Pctlfd(struct ps_prochandle *P)
{
	return (P->ctlfd);
}

/*
 * Return a pointer to the process psinfo structure.
 * Clients should not hold on to this pointer indefinitely.
 * It will become invalid on Prelease().
 */
const psinfo_t *
Ppsinfo(struct ps_prochandle *P)
{
	if (P->state == PS_IDLE) {
		errno = ENODATA;
		return (NULL);
	}

	if (P->state != PS_DEAD && proc_get_psinfo(P->pid, &P->psinfo) == -1)
		return (NULL);

	return (&P->psinfo);
}

/*
 * Return a pointer to the process status structure.
 * Clients should not hold on to this pointer indefinitely.
 * It will become invalid on Prelease().
 */
const pstatus_t *
Pstatus(struct ps_prochandle *P)
{
	return (&P->status);
}

/*
 * Fill in a pointer to a process credentials structure.  The ngroups parameter
 * is the number of supplementary group entries allocated in the caller's cred
 * structure.  It should equal zero or one unless extra space has been
 * allocated for the group list by the caller.
 */
int
Pcred(struct ps_prochandle *P, prcred_t *pcrp, int ngroups)
{
	if (P->state == PS_IDLE) {
		errno = ENODATA;
		return (-1);
	}

	if (P->state != PS_DEAD)
		return (proc_get_cred(P->pid, pcrp, ngroups));

	if (P->core->core_cred != NULL) {
		/*
		 * Avoid returning more supplementary group data than the
		 * caller has allocated in their buffer.  We expect them to
		 * check pr_ngroups afterward and potentially call us again.
		 */
		ngroups = MIN(ngroups, P->core->core_cred->pr_ngroups);

		(void) memcpy(pcrp, P->core->core_cred,
		    sizeof (prcred_t) + (ngroups - 1) * sizeof (gid_t));

		return (0);
	}

	errno = ENODATA;
	return (-1);
}

#if defined(__i386) || defined(__amd64)
/*
 * Fill in a pointer to a process LDT structure.
 * The caller provides a buffer of size 'nldt * sizeof (struct ssd)';
 * If pldt == NULL or nldt == 0, we return the number of existing LDT entries.
 * Otherwise we return the actual number of LDT entries fetched (<= nldt).
 */
int
Pldt(struct ps_prochandle *P, struct ssd *pldt, int nldt)
{
	if (P->state == PS_IDLE) {
		errno = ENODATA;
		return (-1);
	}

	if (P->state != PS_DEAD)
		return (proc_get_ldt(P->pid, pldt, nldt));

	if (pldt == NULL || nldt == 0)
		return (P->core->core_nldt);

	if (P->core->core_ldt != NULL) {
		nldt = MIN(nldt, P->core->core_nldt);

		(void) memcpy(pldt, P->core->core_ldt,
		    nldt * sizeof (struct ssd));

		return (nldt);
	}

	errno = ENODATA;
	return (-1);
}
#endif	/* __i386 */

/*
 * Fill in a pointer to a process privilege structure.
 */
ssize_t
Ppriv(struct ps_prochandle *P, prpriv_t *pprv, size_t size)
{
	if (P->state != PS_DEAD) {
		prpriv_t *pp = proc_get_priv(P->pid);
		if (pp != NULL) {
			size = MIN(size, PRIV_PRPRIV_SIZE(pp));
			(void) memcpy(pprv, pp, size);
			free(pp);
			return (size);
		}
		return (-1);
	}