/*
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  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.
 * 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.
 *
 *      @(#)kern_ktrace.c       8.2 (Berkeley) 9/23/93
 * $FreeBSD: src/sys/kern/kern_ktrace.c,v 1.35.2.6 2002/07/05 22:36:38 darrenr Exp $
 */

#include "opt_ktrace.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/sysmsg.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/fcntl.h>
#include <sys/lock.h>
#include <sys/nlookup.h>
#include <sys/vnode.h>
#include <sys/ktrace.h>
#include <sys/malloc.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/sysent.h>

#include <vm/vm_zone.h>

static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE");

#ifdef KTRACE
static void ktrgetheader (struct ktr_header *kth, int type);
static struct ktr_syscall *ktrgetsyscall(struct ktr_header *kth,
                                struct ktr_syscall *ktp_cache, int narg);
static void ktrputsyscall(struct ktr_syscall *ktp_cache,
                                struct ktr_syscall *ktp);
static void ktrwrite (struct lwp *, struct ktr_header *, struct uio *);
static int ktrcanset (struct thread *,struct proc *);
static int ktrsetchildren (struct thread *, struct proc *,
                                int, int, ktrace_node_t);
static int ktrops (struct thread *,struct proc *,int,int, ktrace_node_t);

/*
 * MPSAFE
 */
static
void
ktrgetheader(struct ktr_header *kth, int type)
{
        thread_t td = curthread;
        struct proc *p = td->td_proc;
        struct lwp *lp = td->td_lwp;

        kth->ktr_type = type;
        /* XXX threaded flag is a hack at the moment */
        kth->ktr_flags = (p->p_nthreads > 1) ? KTRH_THREADED : 0;
        kth->ktr_flags |= KTRH_CPUID_ENCODE(td->td_gd->gd_cpuid);
        /*microtime(&kth->ktr_time); set in ktrwrite */
        kth->ktr_pid = p->p_pid;
        kth->ktr_tid = lp->lwp_tid;
        bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN + 1);
}

static
struct ktr_syscall *
ktrgetsyscall(struct ktr_header *kth, struct ktr_syscall *ktp_cache, int narg)
{
        size_t len;

        len = offsetof(struct ktr_syscall, ktr_args[narg]);
        if (len > sizeof(*ktp_cache))
                ktp_cache = kmalloc(len, M_KTRACE, M_WAITOK);
        kth->ktr_buf = (caddr_t)ktp_cache;
        kth->ktr_len = (int)len;
        return (ktp_cache);
}

static
void
ktrputsyscall(struct ktr_syscall *ktp_cache, struct ktr_syscall *ktp)
{
        if (ktp != ktp_cache)
                kfree(ktp, M_KTRACE);
}

void
ktrsyscall(struct lwp *lp, int code, int narg, union sysunion *uap)
{
        struct ktr_header kth;
        struct ktr_syscall ktp_cache;
        struct ktr_syscall *ktp;
        register_t *argp;
        register_t *args = (void *)uap;
        int i;

        /*
         * Setting the active bit prevents a ktrace recursion from the
         * ktracing op itself.
         */
        lp->lwp_traceflag |= KTRFAC_ACTIVE;
        ktrgetheader(&kth, KTR_SYSCALL);

        ktp = ktrgetsyscall(&kth, &ktp_cache, narg);
        ktp->ktr_code = code;
        ktp->ktr_narg = narg;
        argp = &ktp->ktr_args[0];
        for (i = 0; i < narg; i++)
                *argp++ = args[i];
        ktrwrite(lp, &kth, NULL);

        ktrputsyscall(&ktp_cache, ktp);
        lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
}

void
ktrsysret(struct lwp *lp, int code, int error, register_t retval)
{
        struct ktr_header kth;
        struct ktr_sysret ktp;

        lp->lwp_traceflag |= KTRFAC_ACTIVE;
        ktrgetheader(&kth, KTR_SYSRET);

        ktp.ktr_code = code;
        ktp.ktr_error = error;
        if (error == 0)
                ktp.ktr_retval = retval;                /* what about val2 ? */
        else
                ktp.ktr_retval = 0;

        kth.ktr_buf = (caddr_t)&ktp;
        kth.ktr_len = (int)sizeof(struct ktr_sysret);

        ktrwrite(lp, &kth, NULL);
        lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
}

void
ktrnamei(struct lwp *lp, char *path)
{
        struct ktr_header kth;

        lp->lwp_traceflag |= KTRFAC_ACTIVE;
        ktrgetheader(&kth, KTR_NAMEI);

        kth.ktr_len = (int)strlen(path);
        kth.ktr_buf = path;

        ktrwrite(lp, &kth, NULL);
        lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
}

void
ktrsysctl(struct lwp *lp, int *name, u_int namelen)
{
        struct ktr_header kth;
        u_int mib[CTL_MAXNAME + 2];
        char *mibname;
        size_t mibnamelen;
        int error;

        lp->lwp_traceflag |= KTRFAC_ACTIVE;
        /* Lookup name of mib. */
        KASSERT(namelen <= CTL_MAXNAME, ("sysctl MIB too long"));
        mib[0] = 0;
        mib[1] = 1;
        bcopy(name, mib + 2, namelen * sizeof(*name));
        mibnamelen = 128;
        mibname = kmalloc(mibnamelen, M_KTRACE, M_WAITOK);
        error = kernel_sysctl(mib, namelen + 2, mibname, &mibnamelen,
            NULL, 0, &mibnamelen);
        if (error) {
                kfree(mibname, M_KTRACE);
                lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
                return;
        }
        ktrgetheader(&kth, KTR_SYSCTL);
        kth.ktr_len = mibnamelen;
        kth.ktr_buf = mibname;
        ktrwrite(lp, &kth, NULL);
        lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
}

void
ktrgenio(struct lwp *lp, int fd, enum uio_rw rw, struct uio *uio, int error)
{
        struct ktr_header kth;
        struct ktr_genio ktg;

        if (error)
                return;
        lp->lwp_traceflag |= KTRFAC_ACTIVE;
        ktrgetheader(&kth, KTR_GENIO);

        ktg.ktr_fd = fd;
        ktg.ktr_rw = rw;
        kth.ktr_buf = (caddr_t)&ktg;
        kth.ktr_len = (int)sizeof(struct ktr_genio);
        uio->uio_offset = 0;
        uio->uio_rw = UIO_WRITE;

        ktrwrite(lp, &kth, uio);
        lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
}

void
ktrpsig(struct lwp *lp, int sig, sig_t action, sigset_t *mask, int code)
{
        struct ktr_header kth;
        struct ktr_psig kp;

        lp->lwp_traceflag |= KTRFAC_ACTIVE;
        ktrgetheader(&kth, KTR_PSIG);

        kp.signo = (char)sig;
        kp.action = action;
        kp.mask = *mask;
        kp.code = code;
        kth.ktr_buf = (caddr_t)&kp;
        kth.ktr_len = (int)sizeof(struct ktr_psig);

        ktrwrite(lp, &kth, NULL);
        lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
}

void
ktrcsw(struct lwp *lp, int out, int user)
{
        struct ktr_header kth;
        struct ktr_csw kc;

        lp->lwp_traceflag |= KTRFAC_ACTIVE;
        ktrgetheader(&kth, KTR_CSW);

        kc.out = out;
        kc.user = user;
        kth.ktr_buf = (caddr_t)&kc;
        kth.ktr_len = (int)sizeof(struct ktr_csw);

        ktrwrite(lp, &kth, NULL);
        lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
}
#endif

/* Interface and common routines */

#ifdef KTRACE
/*
 * ktrace system call
 */
struct ktrace_clear_info {
        ktrace_node_t tracenode;
        int rootclear;
        int error;
};

static int ktrace_clear_callback(struct proc *p, void *data);

#endif

/*
 * MPALMOSTSAFE
 */
int
sys_ktrace(struct sysmsg *sysmsg, const struct ktrace_args *uap)
{
#ifdef KTRACE
        struct ktrace_clear_info info;
        struct thread *td = curthread;
        struct proc *curp = td->td_proc;
        struct proc *p;
        struct pgrp *pg;
        int facs = uap->facs & ~KTRFAC_ROOT;
        int ops = KTROP(uap->ops);
        int descend = uap->ops & KTRFLAG_DESCEND;
        int ret = 0;
        int error = 0;
        struct nlookupdata nd;
        ktrace_node_t tracenode = NULL;

        lwkt_gettoken(&curp->p_token);
        curp->p_traceflag |= KTRFAC_ACTIVE;

        if (ops != KTROP_CLEAR) {
                /*
                 * an operation which requires a file argument.
                 */
                error = nlookup_init(&nd, uap->fname, 
                                        UIO_USERSPACE, NLC_LOCKVP);
                if (error == 0)
                        error = vn_open(&nd, NULL, FREAD|FWRITE|O_NOFOLLOW, 0);
                if (error == 0 && nd.nl_open_vp->v_type != VREG)
                        error = EACCES;
                if (error) {
                        curp->p_traceflag &= ~KTRFAC_ACTIVE;
                        nlookup_done(&nd);
                        goto done;
                }
                tracenode = kmalloc(sizeof(struct ktrace_node), M_KTRACE,
                                    M_WAITOK | M_ZERO);
                tracenode->kn_vp = nd.nl_open_vp;
                tracenode->kn_refs = 1;
                nd.nl_open_vp = NULL;
                nlookup_done(&nd);
                vn_unlock(tracenode->kn_vp);
        }
        /*
         * Clear all uses of the tracefile.  Not the most efficient operation
         * in the world.
         */
        if (ops == KTROP_CLEARFILE) {
                info.tracenode = tracenode;
                info.error = 0;
                info.rootclear = 0;
                allproc_scan(ktrace_clear_callback, &info, 0);
                error = info.error;
                goto done;
        }
        /*
         * need something to (un)trace (XXX - why is this here?)
         */
        if (!facs) {
                error = EINVAL;
                goto done;
        }
        /*
         * do it
         */
        if (uap->pid < 0) {
                /*
                 * By process group.  Process group is referenced, preventing
                 * disposal.
                 */
                pg = pgfind(-uap->pid);
                if (pg == NULL) {
                        error = ESRCH;
                        goto done;
                }
                lwkt_gettoken(&pg->pg_token);
                LIST_FOREACH(p, &pg->pg_members, p_pglist) {
                        PHOLD(p);
                        if (descend)
                                ret |= ktrsetchildren(td, p, ops, facs, tracenode);
                        else
                                ret |= ktrops(td, p, ops, facs, tracenode);
                        PRELE(p);
                }
                lwkt_reltoken(&pg->pg_token);
                pgrel(pg);
        } else {
                /*
                 * by pid
                 */
                p = pfind(uap->pid);
                if (p == NULL) {
                        error = ESRCH;
                        goto done;
                }
                if (descend)
                        ret |= ktrsetchildren(td, p, ops, facs, tracenode);
                else
                        ret |= ktrops(td, p, ops, facs, tracenode);
                PRELE(p);
        }
        if (!ret)
                error = EPERM;
done:
        if (tracenode)
                ktrdestroy(&tracenode);
        curp->p_traceflag &= ~KTRFAC_ACTIVE;
        lwkt_reltoken(&curp->p_token);
        return (error);
#else
        return ENOSYS;
#endif
}

#ifdef KTRACE

/*
 * NOTE: NOT MPSAFE (yet)
 */
static int
ktrace_clear_callback(struct proc *p, void *data)
{
        struct ktrace_clear_info *info = data;

        if (p->p_tracenode) {
                if (info->rootclear) {
                        if (p->p_tracenode == info->tracenode) {
                                ktrdestroy(&p->p_tracenode);
                                p->p_traceflag = 0;
                        }
                } else {
                        if (p->p_tracenode->kn_vp == info->tracenode->kn_vp) {
                                if (ktrcanset(curthread, p)) {
                                        ktrdestroy(&p->p_tracenode);
                                        p->p_traceflag = 0;
                                } else {
                                        info->error = EPERM;
                                }
                        }
                }
        }
        return(0);
}

#endif

/*
 * utrace system call
 *
 * MPALMOSTSAFE
 */
int
sys_utrace(struct sysmsg *sysmsg, const struct utrace_args *uap)
{
#ifdef KTRACE
        struct ktr_header kth;
        struct thread *td = curthread;  /* XXX */
        char cp_cache[64];
        caddr_t cp;

        if (!KTRPOINT(td, KTR_USER))
                return (0);
        if (uap->len > KTR_USER_MAXLEN)
                return (EINVAL);
        td->td_lwp->lwp_traceflag |= KTRFAC_ACTIVE;
        ktrgetheader(&kth, KTR_USER);
        if (uap->len <= sizeof(cp_cache))
                cp = cp_cache;
        else
                cp = kmalloc(uap->len, M_KTRACE, M_WAITOK);

        if (!copyin(uap->addr, cp, uap->len)) {
                kth.ktr_buf = cp;
                kth.ktr_len = uap->len;
                ktrwrite(td->td_lwp, &kth, NULL);
        }
        if (cp != cp_cache)
                kfree(cp, M_KTRACE);
        td->td_lwp->lwp_traceflag &= ~KTRFAC_ACTIVE;

        return (0);
#else
        return (ENOSYS);
#endif
}

void
ktrdestroy(struct ktrace_node **tracenodep)
{
        ktrace_node_t tracenode;

        if ((tracenode = *tracenodep) != NULL) {
                *tracenodep = NULL;
                KKASSERT(tracenode->kn_refs > 0);
                if (atomic_fetchadd_int(&tracenode->kn_refs, -1) == 1) {
                        vn_close(tracenode->kn_vp, FREAD|FWRITE, NULL);
                        tracenode->kn_vp = NULL;
                        kfree(tracenode, M_KTRACE);
                }
        }
}

/*
 * This allows a process to inherit a ref on a tracenode and is also used
 * as a temporary ref to prevent a tracenode from being destroyed out from
 * under an active operation.
 */
ktrace_node_t
ktrinherit(ktrace_node_t tracenode)
{
        if (tracenode) {
                KKASSERT(tracenode->kn_refs > 0);
                atomic_add_int(&tracenode->kn_refs, 1);
        }
        return(tracenode);
}

#ifdef KTRACE
static int
ktrops(struct thread *td, struct proc *p, int ops, int facs,
       ktrace_node_t tracenode)
{
        ktrace_node_t oldnode;

        if (!ktrcanset(td, p))
                return (0);
        if (ops == KTROP_SET) {
                if ((oldnode = p->p_tracenode) != tracenode) {
                        p->p_tracenode = ktrinherit(tracenode);
                        ktrdestroy(&oldnode);
                }
                p->p_traceflag |= facs;
                if (td->td_ucred->cr_uid == 0)
                        p->p_traceflag |= KTRFAC_ROOT;
        } else {
                /* KTROP_CLEAR */
                if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
                        /* no more tracing */
                        p->p_traceflag = 0;
                        ktrdestroy(&p->p_tracenode);
                }
        }

        return (1);
}

static int
ktrsetchildren(struct thread *td, struct proc *top, int ops, int facs,
               ktrace_node_t tracenode)
{
        struct proc *p;
        struct proc *np;
        int ret = 0;

        p = top;
        PHOLD(p);
        lwkt_gettoken(&p->p_token);

        for (;;) {
                ret |= ktrops(td, p, ops, facs, tracenode);

                /*
                 * If this process has children, descend to them next,
                 * otherwise do any siblings, and if done with this level,
                 * follow back up the tree (but not past top).
                 */
                if ((np = LIST_FIRST(&p->p_children)) != NULL) {
                        PHOLD(np);
                }
                while (np == NULL) {
                        if (p == top)
                                break;
                        if ((np = LIST_NEXT(p, p_sibling)) != NULL) {
                                PHOLD(np);
                                break;
                        }

                        /*
                         * recurse up to parent, set p in our inner
                         * loop when doing this.  np can be NULL if
                         * we race a reparenting to init (thus 'top'
                         * is skipped past and never encountered).
                         */
                        np = p->p_pptr;
                        if (np == NULL)
                                break;
                        PHOLD(np);
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        p = np;
                        lwkt_gettoken(&p->p_token);
                        np = NULL;
                }
                lwkt_reltoken(&p->p_token);
                PRELE(p);
                p = np;
                if (p == NULL)
                        break;
                /* Already held, but we need the token too */
                lwkt_gettoken(&p->p_token);
        }
        return (ret);
}

static void
ktrwrite(struct lwp *lp, struct ktr_header *kth, struct uio *uio)
{
        struct ktrace_clear_info info;
        struct uio auio;
        struct iovec aiov[2];
        int error;
        ktrace_node_t tracenode;

        /*
         * We have to ref our tracenode to prevent it from being ripped out
         * from under us while we are trying to use it.   p_tracenode can
         * go away at any time if another process gets a write error.
         *
         * XXX not MP safe
         */
        if (lp->lwp_proc->p_tracenode == NULL)
                return;
        tracenode = ktrinherit(lp->lwp_proc->p_tracenode);
        auio.uio_iov = &aiov[0];
        auio.uio_offset = 0;
        auio.uio_segflg = UIO_SYSSPACE;
        auio.uio_rw = UIO_WRITE;
        aiov[0].iov_base = (caddr_t)kth;
        aiov[0].iov_len = sizeof(struct ktr_header);
        auio.uio_resid = sizeof(struct ktr_header);
        auio.uio_iovcnt = 1;
        auio.uio_td = curthread;
        if (kth->ktr_len > 0) {
                auio.uio_iovcnt++;
                aiov[1].iov_base = kth->ktr_buf;
                aiov[1].iov_len = kth->ktr_len;
                auio.uio_resid += kth->ktr_len;
                if (uio != NULL)
                        kth->ktr_len += uio->uio_resid;
        }

        /*
         * NOTE: Must set timestamp after obtaining lock to ensure no
         *       timestamp reversals in the output file.
         */
        vn_lock(tracenode->kn_vp, LK_EXCLUSIVE | LK_RETRY);
        microtime(&kth->ktr_time);
        error = VOP_WRITE(tracenode->kn_vp, &auio,
                          IO_UNIT | IO_APPEND, lp->lwp_thread->td_ucred);
        if (error == 0 && uio != NULL) {
                error = VOP_WRITE(tracenode->kn_vp, uio,
                              IO_UNIT | IO_APPEND, lp->lwp_thread->td_ucred);
        }
        vn_unlock(tracenode->kn_vp);
        if (error) {
                /*
                 * If an error occured, give up tracing on all processes
                 * using this tracenode.  This is not MP safe but is
                 * blocking-safe.
                 */
                log(LOG_NOTICE,
                    "ktrace write failed, errno %d, tracing stopped\n", error);
                info.tracenode = tracenode;
                info.error = 0;
                info.rootclear = 1;
                allproc_scan(ktrace_clear_callback, &info, 0);
        }
        ktrdestroy(&tracenode);
}

/*
 * Return true if caller has permission to set the ktracing state
 * of target.  Essentially, the target can't possess any
 * more permissions than the caller.  KTRFAC_ROOT signifies that
 * root previously set the tracing status on the target process, and
 * so, only root may further change it.
 *
 * TODO: check groups.  use caller effective gid.
 */
static int
ktrcanset(struct thread *calltd, struct proc *targetp)
{
        struct ucred *caller = calltd->td_ucred;
        struct ucred *target = targetp->p_ucred;

        if (!PRISON_CHECK(caller, target))
                return (0);
        if ((caller->cr_uid == target->cr_ruid &&
             target->cr_ruid == target->cr_svuid &&
             caller->cr_rgid == target->cr_rgid &&      /* XXX */
             target->cr_rgid == target->cr_svgid &&
             (targetp->p_traceflag & KTRFAC_ROOT) == 0 &&
             (targetp->p_flags & P_SUGID) == 0) ||
             caller->cr_uid == 0)
                return (1);

        return (0);
}

#endif /* KTRACE */