/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2021 Edward Tomasz Napierala <trasz@FreeBSD.org>
 * Copyright (c) 2018 Chuck Tuffli
 * Copyright (c) 2017 Dell EMC
 * Copyright (c) 2000 David O'Brien
 * Copyright (c) 1995-1996 Søren Schmidt
 * Copyright (c) 1996 Peter Wemm
 * All rights reserved.
 *
 * This software was developed by the University of Cambridge Computer
 * Laboratory as part of the CHERI for Hypervisors and Operating Systems
 * (CHaOS) project, funded by EPSRC grant EP/V000292/1.
 *
 * 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
 *    in this position and unchanged.
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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/param.h>
#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/imgact_elf.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/procfs.h>
#include <sys/reg.h>
#include <sys/sbuf.h>
#include <sys/sysent.h>

#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>

#include <machine/elf.h>

#ifdef COMPAT_LINUX32
#define linux_pt_regset linux_pt_regset32
#define bsd_to_linux_regset bsd_to_linux_regset32
#include <machine/../linux32/linux.h>
#else
#include <machine/../linux/linux.h>
#endif
#include <compat/linux/linux_elf.h>
#include <compat/linux/linux_mib.h>
#include <compat/linux/linux_misc.h>

struct l_elf_siginfo {
        l_int           si_signo;
        l_int           si_code;
        l_int           si_errno;
};

typedef struct linux_pt_regset l_elf_gregset_t;

struct linux_elf_prstatus {
        struct l_elf_siginfo pr_info;
        l_short         pr_cursig;
        l_ulong         pr_sigpend;
        l_ulong         pr_sighold;
        l_pid_t         pr_pid;
        l_pid_t         pr_ppid;
        l_pid_t         pr_pgrp;
        l_pid_t         pr_sid;
        l_timeval       pr_utime;
        l_timeval       pr_stime;
        l_timeval       pr_cutime;
        l_timeval       pr_cstime;
        l_elf_gregset_t pr_reg;
        l_int           pr_fpvalid;
};

#define LINUX_NT_AUXV   6

static void __linuxN(note_fpregset)(void *, struct sbuf *, size_t *);
static void __linuxN(note_prpsinfo)(void *, struct sbuf *, size_t *);
static void __linuxN(note_prstatus)(void *, struct sbuf *, size_t *);
static void __linuxN(note_threadmd)(void *, struct sbuf *, size_t *);
static void __linuxN(note_nt_auxv)(void *, struct sbuf *, size_t *);

void
__linuxN(prepare_notes)(struct thread *td, struct note_info_list *list,
    size_t *sizep)
{
        struct proc *p;
        struct thread *thr;
        size_t size;

        p = td->td_proc;
        size = 0;

        /*
         * To have the debugger select the right thread (LWP) as the initial
         * thread, we dump the state of the thread passed to us in td first.
         * This is the thread that causes the core dump and thus likely to
         * be the right thread one wants to have selected in the debugger.
         */
        thr = td;
        while (thr != NULL) {
                size += __elfN(register_note)(td, list,
                    NT_PRSTATUS, __linuxN(note_prstatus), thr);
                size += __elfN(register_note)(td, list,
                    NT_PRPSINFO, __linuxN(note_prpsinfo), p);
                size += __elfN(register_note)(td, list,
                    LINUX_NT_AUXV, __linuxN(note_nt_auxv), p);
                size += __elfN(register_note)(td, list,
                    NT_FPREGSET, __linuxN(note_fpregset), thr);
                size += __elfN(register_note)(td, list,
                    -1, __linuxN(note_threadmd), thr);

                thr = thr == td ? TAILQ_FIRST(&p->p_threads) :
                    TAILQ_NEXT(thr, td_plist);
                if (thr == td)
                        thr = TAILQ_NEXT(thr, td_plist);
        }

        *sizep = size;
}

typedef struct linux_elf_prstatus linux_elf_prstatus_t;
#ifdef COMPAT_LINUX32
typedef struct prpsinfo32 linux_elf_prpsinfo_t;
typedef struct fpreg32 linux_elf_prfpregset_t;
#else
typedef prpsinfo_t linux_elf_prpsinfo_t;
typedef prfpregset_t linux_elf_prfpregset_t;
#endif

static void
__linuxN(note_prpsinfo)(void *arg, struct sbuf *sb, size_t *sizep)
{
        struct sbuf sbarg;
        size_t len;
        char *cp, *end;
        struct proc *p;
        linux_elf_prpsinfo_t *psinfo;
        int error;

        p = arg;
        if (sb != NULL) {
                KASSERT(*sizep == sizeof(*psinfo), ("invalid size"));
                psinfo = malloc(sizeof(*psinfo), M_TEMP, M_ZERO | M_WAITOK);
                psinfo->pr_version = PRPSINFO_VERSION;
                psinfo->pr_psinfosz = sizeof(linux_elf_prpsinfo_t);
                strlcpy(psinfo->pr_fname, p->p_comm, sizeof(psinfo->pr_fname));
                PROC_LOCK(p);
                if (p->p_args != NULL) {
                        len = sizeof(psinfo->pr_psargs) - 1;
                        if (len > p->p_args->ar_length)
                                len = p->p_args->ar_length;
                        memcpy(psinfo->pr_psargs, p->p_args->ar_args, len);
                        PROC_UNLOCK(p);
                        error = 0;
                } else {
                        _PHOLD(p);
                        PROC_UNLOCK(p);
                        sbuf_new(&sbarg, psinfo->pr_psargs,
                            sizeof(psinfo->pr_psargs), SBUF_FIXEDLEN);
                        error = proc_getargv(curthread, p, &sbarg);
                        PRELE(p);
                        if (sbuf_finish(&sbarg) == 0) {
                                len = sbuf_len(&sbarg) - 1;
                                if (len > 0)
                                        len--;
                        } else {
                                len = sizeof(psinfo->pr_psargs) - 1;
                        }
                        sbuf_delete(&sbarg);
                }
                if (error != 0 || len == 0 || (ssize_t)len == -1)
                        strlcpy(psinfo->pr_psargs, p->p_comm,
                            sizeof(psinfo->pr_psargs));
                else {
                        KASSERT(len < sizeof(psinfo->pr_psargs),
                            ("len is too long: %zu vs %zu", len,
                            sizeof(psinfo->pr_psargs)));
                        cp = psinfo->pr_psargs;
                        end = cp + len - 1;
                        for (;;) {
                                cp = memchr(cp, '\0', end - cp);
                                if (cp == NULL)
                                        break;
                                *cp = ' ';
                        }
                }
                psinfo->pr_pid = p->p_pid;
                sbuf_bcat(sb, psinfo, sizeof(*psinfo));
                free(psinfo, M_TEMP);
        }
        *sizep = sizeof(*psinfo);
}

static void
__linuxN(note_prstatus)(void *arg, struct sbuf *sb, size_t *sizep)
{
        struct thread *td;
        linux_elf_prstatus_t *status;
#ifdef COMPAT_LINUX32
        struct reg32 pr_reg;
#else
        struct reg pr_reg;
#endif

        td = arg;
        if (sb != NULL) {
                KASSERT(*sizep == sizeof(*status), ("invalid size"));
                status = malloc(sizeof(*status), M_TEMP, M_ZERO | M_WAITOK);

                /*
                 * XXX: Some fields missing.
                 */
                status->pr_cursig = td->td_proc->p_sig;
                status->pr_pid = td->td_tid;

#ifdef COMPAT_LINUX32
                fill_regs32(td, &pr_reg);
#else
                fill_regs(td, &pr_reg);
#endif
                bsd_to_linux_regset(&pr_reg, &status->pr_reg);
                sbuf_bcat(sb, status, sizeof(*status));
                free(status, M_TEMP);
        }
        *sizep = sizeof(*status);
}

static void
__linuxN(note_fpregset)(void *arg, struct sbuf *sb, size_t *sizep)
{
        struct thread *td;
        linux_elf_prfpregset_t *fpregset;

        td = arg;
        if (sb != NULL) {
                KASSERT(*sizep == sizeof(*fpregset), ("invalid size"));
                fpregset = malloc(sizeof(*fpregset), M_TEMP, M_ZERO | M_WAITOK);
#ifdef COMPAT_LINUX32
                fill_fpregs32(td, fpregset);
#else
                fill_fpregs(td, fpregset);
#endif
                sbuf_bcat(sb, fpregset, sizeof(*fpregset));
                free(fpregset, M_TEMP);
        }
        *sizep = sizeof(*fpregset);
}

/*
 * Allow for MD specific notes, as well as any MD
 * specific preparations for writing MI notes.
 */
static void
__linuxN(note_threadmd)(void *arg, struct sbuf *sb, size_t *sizep)
{
        struct thread *td;
        void *buf;
        size_t size;

        td = arg;
        size = *sizep;
        if (size != 0 && sb != NULL)
                buf = malloc(size, M_TEMP, M_ZERO | M_WAITOK);
        else
                buf = NULL;
        size = 0;
        __elfN(dump_thread)(td, buf, &size);
        KASSERT(sb == NULL || *sizep == size, ("invalid size"));
        if (size != 0 && sb != NULL)
                sbuf_bcat(sb, buf, size);
        free(buf, M_TEMP);
        *sizep = size;
}

static void
__linuxN(note_nt_auxv)(void *arg, struct sbuf *sb, size_t *sizep)
{
        struct proc *p;
        size_t size;

        p = arg;
        if (sb == NULL) {
                size = 0;
                sb = sbuf_new(NULL, NULL, LINUX_AT_COUNT * sizeof(Elf_Auxinfo),
                    SBUF_FIXEDLEN);
                sbuf_set_drain(sb, sbuf_count_drain, &size);
                PHOLD(p);
                proc_getauxv(curthread, p, sb);
                PRELE(p);
                sbuf_finish(sb);
                sbuf_delete(sb);
                *sizep = size;
        } else {
                PHOLD(p);
                proc_getauxv(curthread, p, sb);
                PRELE(p);
        }
}

/*
 * Copy strings out to the new process address space, constructing new arg
 * and env vector tables. Return a pointer to the base so that it can be used
 * as the initial stack pointer.
 */
int
__linuxN(copyout_strings)(struct image_params *imgp, uintptr_t *stack_base)
{
        char canary[LINUX_AT_RANDOM_LEN];
        char **vectp;
        char *stringp;
        uintptr_t destp, ustringp;
        struct ps_strings *arginfo;
        struct proc *p;
        size_t execpath_len;
        int argc, envc;
        int error;

        p = imgp->proc;
        destp = PROC_PS_STRINGS(p);
        arginfo = imgp->ps_strings = (void *)destp;

        /*
         * Copy the image path for the rtld.
         */
        if (imgp->execpath != NULL && imgp->auxargs != NULL) {
                execpath_len = strlen(imgp->execpath) + 1;
                destp -= execpath_len;
                destp = rounddown2(destp, sizeof(void *));
                imgp->execpathp = (void *)destp;
                error = copyout(imgp->execpath, imgp->execpathp, execpath_len);
                if (error != 0)
                        return (error);
        }

        /*
         * Prepare the canary for SSP.
         */
        arc4rand(canary, sizeof(canary), 0);
        destp -= sizeof(canary);
        imgp->canary = (void *)destp;
        error = copyout(canary, imgp->canary, sizeof(canary));
        if (error != 0)
                return (error);
        imgp->canarylen = sizeof(canary);

        /*
         * Allocate room for the argument and environment strings.
         */
        destp -= ARG_MAX - imgp->args->stringspace;
        destp = rounddown2(destp, sizeof(void *));
        ustringp = destp;

        if (imgp->auxargs) {
                /*
                 * Allocate room on the stack for the ELF auxargs
                 * array.  It has up to LINUX_AT_COUNT entries.
                 */
                destp -= LINUX_AT_COUNT * sizeof(Elf_Auxinfo);
                destp = rounddown2(destp, sizeof(void *));
        }

        vectp = (char **)destp;

        /*
         * Allocate room for the argv[] and env vectors including the
         * terminating NULL pointers.
         */
        vectp -= imgp->args->argc + 1 + imgp->args->envc + 1;

        /*
         * Starting with 2.24, glibc depends on a 16-byte stack alignment.
         */
        vectp = (char **)((((uintptr_t)vectp + 8) & ~0xF) - 8);

        /*
         * vectp also becomes our initial stack base
         */
        *stack_base = (uintptr_t)vectp;

        stringp = imgp->args->begin_argv;
        argc = imgp->args->argc;
        envc = imgp->args->envc;

        /*
         * Copy out strings - arguments and environment.
         */
        error = copyout(stringp, (void *)ustringp,
            ARG_MAX - imgp->args->stringspace);
        if (error != 0)
                return (error);

        /*
         * Fill in "ps_strings" struct for ps, w, etc.
         */
        imgp->argv = vectp;
        if (suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp) != 0 ||
            suword32(&arginfo->ps_nargvstr, argc) != 0)
                return (EFAULT);

        /*
         * Fill in argument portion of vector table.
         */
        for (; argc > 0; --argc) {
                if (suword(vectp++, ustringp) != 0)
                        return (EFAULT);
                while (*stringp++ != 0)
                        ustringp++;
                ustringp++;
        }

        /* a null vector table pointer separates the argp's from the envp's */
        if (suword(vectp++, 0) != 0)
                return (EFAULT);

        imgp->envv = vectp;
        if (suword(&arginfo->ps_envstr, (long)(intptr_t)vectp) != 0 ||
            suword32(&arginfo->ps_nenvstr, envc) != 0)
                return (EFAULT);

        /*
         * Fill in environment portion of vector table.
         */
        for (; envc > 0; --envc) {
                if (suword(vectp++, ustringp) != 0)
                        return (EFAULT);
                while (*stringp++ != 0)
                        ustringp++;
                ustringp++;
        }

        /* end of vector table is a null pointer */
        if (suword(vectp, 0) != 0)
                return (EFAULT);

        if (imgp->auxargs) {
                vectp++;
                error = imgp->sysent->sv_copyout_auxargs(imgp,
                    (uintptr_t)vectp);
                if (error != 0)
                        return (error);
        }

        return (0);
}

bool
linux_trans_osrel(const Elf_Note *note, int32_t *osrel)
{
        const Elf32_Word *desc;
        uintptr_t p;

        p = (uintptr_t)(note + 1);
        p += roundup2(note->n_namesz, sizeof(Elf32_Addr));

        desc = (const Elf32_Word *)p;
        if (desc[0] != GNU_ABI_LINUX)
                return (false);
        /*
         * For Linux we encode osrel using the Linux convention of
         *      (version << 16) | (major << 8) | (minor)
         * See macro in linux_mib.h
         */
        *osrel = LINUX_KERNVER(desc[1], desc[2], desc[3]);

        return (true);
}

int
__linuxN(copyout_auxargs)(struct image_params *imgp, uintptr_t base)
{
        struct thread *td = curthread;
        Elf_Auxargs *args;
        Elf_Auxinfo *aarray, *pos;
        struct proc *p;
        int error, issetugid;

        p = imgp->proc;
        issetugid = p->p_flag & P_SUGID ? 1 : 0;
        args = imgp->auxargs;
        aarray = pos = malloc(LINUX_AT_COUNT * sizeof(*pos), M_TEMP,
            M_WAITOK | M_ZERO);

        __linuxN(arch_copyout_auxargs)(imgp, &pos);
        /*
         * Do not export AT_CLKTCK when emulating Linux kernel prior to 2.4.0,
         * as it has appeared in the 2.4.0-rc7 first time.
         * Being exported, AT_CLKTCK is returned by sysconf(_SC_CLK_TCK),
         * glibc falls back to the hard-coded CLK_TCK value when aux entry
         * is not present.
         * Also see linux_times() implementation.
         */
        if (linux_kernver(td) >= LINUX_KERNVER(2,4,0))
                AUXARGS_ENTRY(pos, LINUX_AT_CLKTCK, stclohz);
        AUXARGS_ENTRY(pos, AT_PAGESZ, args->pagesz);
        AUXARGS_ENTRY(pos, AT_PHDR, args->phdr);
        AUXARGS_ENTRY(pos, AT_PHENT, args->phent);
        AUXARGS_ENTRY(pos, AT_PHNUM, args->phnum);
        AUXARGS_ENTRY(pos, AT_BASE, args->base);
        AUXARGS_ENTRY(pos, AT_FLAGS, args->flags);
        AUXARGS_ENTRY(pos, AT_ENTRY, args->entry);
        AUXARGS_ENTRY(pos, AT_UID, imgp->proc->p_ucred->cr_ruid);
        AUXARGS_ENTRY(pos, AT_EUID, imgp->proc->p_ucred->cr_svuid);
        AUXARGS_ENTRY(pos, AT_GID, imgp->proc->p_ucred->cr_rgid);
        AUXARGS_ENTRY(pos, AT_EGID, imgp->proc->p_ucred->cr_svgid);
        AUXARGS_ENTRY(pos, LINUX_AT_SECURE, issetugid);
        if (linux_kernver(td) >= LINUX_KERNVER(2,6,30))
                AUXARGS_ENTRY_PTR(pos, LINUX_AT_RANDOM, imgp->canary);
        if (linux_kernver(td) >= LINUX_KERNVER(2,6,26) && imgp->execpathp != 0)
                AUXARGS_ENTRY(pos, LINUX_AT_EXECFN, PTROUT(imgp->execpathp));
        if (args->execfd != -1)
                AUXARGS_ENTRY(pos, AT_EXECFD, args->execfd);
        if (linux_kernver(td) >= LINUX_KERNVER(5,13,0))
                AUXARGS_ENTRY(pos, LINUX_AT_MINSIGSTKSZ,
                    imgp->sysent->sv_minsigstksz);
        AUXARGS_ENTRY(pos, AT_NULL, 0);

        free(imgp->auxargs, M_TEMP);
        imgp->auxargs = NULL;
        KASSERT(pos - aarray <= LINUX_AT_COUNT, ("Too many auxargs"));

        error = copyout(aarray, PTRIN(base), sizeof(*aarray) * LINUX_AT_COUNT);
        free(aarray, M_TEMP);
        return (error);
}