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snp.c
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Editing: snp.c
/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org> * All rights reserved. * * 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. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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. */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); #include <sys/param.h> #include <sys/conf.h> #include <sys/fcntl.h> #include <sys/filio.h> #include <sys/kernel.h> #include <sys/malloc.h> #include <sys/module.h> #include <sys/poll.h> #include <sys/proc.h> #include <sys/snoop.h> #include <sys/sx.h> #include <sys/systm.h> #include <sys/tty.h> #include <sys/uio.h> static struct cdev *snp_dev; static MALLOC_DEFINE(M_SNP, "snp", "tty snoop device"); /* XXX: should be mtx, but TTY can be locked by Giant. */ #if 0 static struct mtx snp_register_lock; MTX_SYSINIT(snp_register_lock, &snp_register_lock, "tty snoop registration", MTX_DEF); #define SNP_LOCK() mtx_lock(&snp_register_lock) #define SNP_UNLOCK() mtx_unlock(&snp_register_lock) #else static struct sx snp_register_lock; SX_SYSINIT(snp_register_lock, &snp_register_lock, "tty snoop registration"); #define SNP_LOCK() sx_xlock(&snp_register_lock) #define SNP_UNLOCK() sx_xunlock(&snp_register_lock) #endif #define SNPGTYY_32DEV _IOR('T', 89, uint32_t) /* * There is no need to have a big input buffer. In most typical setups, * we won't inject much data into the TTY, because users can't type * really fast. */ #define SNP_INPUT_BUFSIZE 16 /* * The output buffer has to be really big. Right now we don't support * any form of flow control, which means we lost any data we can't * accept. We set the output buffer size to about twice the size of a * pseudo-terminal/virtual console's output buffer. */ #define SNP_OUTPUT_BUFSIZE 16384 static d_open_t snp_open; static d_read_t snp_read; static d_write_t snp_write; static d_ioctl_t snp_ioctl; static d_poll_t snp_poll; static struct cdevsw snp_cdevsw = { .d_version = D_VERSION, .d_open = snp_open, .d_read = snp_read, .d_write = snp_write, .d_ioctl = snp_ioctl, .d_poll = snp_poll, .d_name = "snp", }; static th_getc_capture_t snp_getc_capture; static struct ttyhook snp_hook = { .th_getc_capture = snp_getc_capture, }; /* * Per-instance structure. * * List of locks * (r) locked by snp_register_lock on assignment * (t) locked by tty_lock */ struct snp_softc { struct tty *snp_tty; /* (r) TTY we're snooping. */ struct ttyoutq snp_outq; /* (t) Output queue. */ struct cv snp_outwait; /* (t) Output wait queue. */ struct selinfo snp_outpoll; /* (t) Output polling. */ }; static void snp_dtor(void *data) { struct snp_softc *ss = data; struct tty *tp; tp = ss->snp_tty; if (tp != NULL) { tty_lock(tp); ttyoutq_free(&ss->snp_outq); ttyhook_unregister(tp); } cv_destroy(&ss->snp_outwait); free(ss, M_SNP); } /* * Snoop device node routines. */ static int snp_open(struct cdev *dev, int flag, int mode, struct thread *td) { struct snp_softc *ss; /* Allocate per-snoop data. */ ss = malloc(sizeof(struct snp_softc), M_SNP, M_WAITOK|M_ZERO); cv_init(&ss->snp_outwait, "snp out"); devfs_set_cdevpriv(ss, snp_dtor); return (0); } static int snp_read(struct cdev *dev, struct uio *uio, int flag) { int error, oresid = uio->uio_resid; struct snp_softc *ss; struct tty *tp; if (uio->uio_resid == 0) return (0); error = devfs_get_cdevpriv((void **)&ss); if (error != 0) return (error); tp = ss->snp_tty; if (tp == NULL || tty_gone(tp)) return (EIO); tty_lock(tp); for (;;) { error = ttyoutq_read_uio(&ss->snp_outq, tp, uio); if (error != 0 || uio->uio_resid != oresid) break; /* Wait for more data. */ if (flag & O_NONBLOCK) { error = EWOULDBLOCK; break; } error = cv_wait_sig(&ss->snp_outwait, tty_getlock(tp)); if (error != 0) break; if (tty_gone(tp)) { error = EIO; break; } } tty_unlock(tp); return (error); } static int snp_write(struct cdev *dev, struct uio *uio, int flag) { struct snp_softc *ss; struct tty *tp; int error, len; char in[SNP_INPUT_BUFSIZE]; error = devfs_get_cdevpriv((void **)&ss); if (error != 0) return (error); tp = ss->snp_tty; if (tp == NULL || tty_gone(tp)) return (EIO); while (uio->uio_resid > 0) { /* Read new data. */ len = imin(uio->uio_resid, sizeof in); error = uiomove(in, len, uio); if (error != 0) return (error); tty_lock(tp); /* Driver could have abandoned the TTY in the mean time. */ if (tty_gone(tp)) { tty_unlock(tp); return (ENXIO); } /* * Deliver data to the TTY. Ignore errors for now, * because we shouldn't bail out when we're running * close to the watermarks. */ ttydisc_rint_simple(tp, in, len); ttydisc_rint_done(tp); tty_unlock(tp); } return (0); } static int snp_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags, struct thread *td) { struct snp_softc *ss; struct tty *tp; int error; error = devfs_get_cdevpriv((void **)&ss); if (error != 0) return (error); switch (cmd) { case SNPSTTY: /* Bind TTY to snoop instance. */ SNP_LOCK(); if (ss->snp_tty != NULL) { SNP_UNLOCK(); return (EBUSY); } /* * XXXRW / XXXJA: no capability check here. */ error = ttyhook_register(&ss->snp_tty, td->td_proc, *(int *)data, &snp_hook, ss); SNP_UNLOCK(); if (error != 0) return (error); /* Now that went okay, allocate a buffer for the queue. */ tp = ss->snp_tty; tty_lock(tp); ttyoutq_setsize(&ss->snp_outq, tp, SNP_OUTPUT_BUFSIZE); tty_unlock(tp); return (0); case SNPGTTY: /* Obtain device number of associated TTY. */ if (ss->snp_tty == NULL) *(dev_t *)data = NODEV; else *(dev_t *)data = tty_udev(ss->snp_tty); return (0); case SNPGTYY_32DEV: if (ss->snp_tty == NULL) *(uint32_t *)data = -1; else *(uint32_t *)data = tty_udev(ss->snp_tty); /* trunc */ return (0); case FIONREAD: tp = ss->snp_tty; if (tp != NULL) { tty_lock(tp); *(int *)data = ttyoutq_bytesused(&ss->snp_outq); tty_unlock(tp); } else { *(int *)data = 0; } return (0); default: return (ENOTTY); } } static int snp_poll(struct cdev *dev, int events, struct thread *td) { struct snp_softc *ss; struct tty *tp; int revents; if (devfs_get_cdevpriv((void **)&ss) != 0) return (events & (POLLHUP|POLLIN|POLLRDNORM|POLLOUT|POLLWRNORM)); revents = 0; if (events & (POLLIN | POLLRDNORM)) { tp = ss->snp_tty; if (tp != NULL) { tty_lock(tp); if (ttyoutq_bytesused(&ss->snp_outq) > 0) revents |= events & (POLLIN | POLLRDNORM); tty_unlock(tp); } } if (revents == 0) selrecord(td, &ss->snp_outpoll); return (revents); } /* * TTY hook events. */ static int snp_modevent(module_t mod, int type, void *data) { switch (type) { case MOD_LOAD: snp_dev = make_dev(&snp_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "snp"); return (0); case MOD_UNLOAD: /* XXX: Make existing users leave. */ destroy_dev(snp_dev); return (0); default: return (EOPNOTSUPP); } } static void snp_getc_capture(struct tty *tp, const void *buf, size_t len) { struct snp_softc *ss = ttyhook_softc(tp); ttyoutq_write(&ss->snp_outq, buf, len); cv_broadcast(&ss->snp_outwait); selwakeup(&ss->snp_outpoll); } static moduledata_t snp_mod = { "snp", snp_modevent, NULL }; DECLARE_MODULE(snp, snp_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
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