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[netbsd-mini2440.git] / sys / kern / exec_elf.c

/*      $NetBSD$        */

/*-
 * Copyright (c) 1994, 2000, 2005 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christos Zoulas.
 *
 * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * Copyright (c) 1996 Christopher G. Demetriou
 * 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. 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/cdefs.h>
__KERNEL_RCSID(1, "$NetBSD$");

#ifdef _KERNEL_OPT
#include "opt_pax.h"
#endif /* _KERNEL_OPT */

#include <sys/param.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/kmem.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/exec.h>
#include <sys/exec_elf.h>
#include <sys/syscall.h>
#include <sys/signalvar.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/kauth.h>
#include <sys/bitops.h>

#include <sys/cpu.h>
#include <machine/reg.h>

#include <compat/common/compat_util.h>

#include <sys/pax.h>

extern struct emul emul_netbsd;

#define elf_check_header        ELFNAME(check_header)
#define elf_copyargs            ELFNAME(copyargs)
#define elf_load_file           ELFNAME(load_file)
#define elf_load_psection       ELFNAME(load_psection)
#define exec_elf_makecmds       ELFNAME2(exec,makecmds)
#define netbsd_elf_signature    ELFNAME2(netbsd,signature)
#define netbsd_elf_probe        ELFNAME2(netbsd,probe)
#define coredump                ELFNAMEEND(coredump)

int     elf_load_file(struct lwp *, struct exec_package *, char *,
            struct exec_vmcmd_set *, u_long *, struct elf_args *, Elf_Addr *);
void    elf_load_psection(struct exec_vmcmd_set *, struct vnode *,
            const Elf_Phdr *, Elf_Addr *, u_long *, int *, int);

int     netbsd_elf_signature(struct lwp *, struct exec_package *, Elf_Ehdr *);
int     netbsd_elf_probe(struct lwp *, struct exec_package *, void *, char *,
            vaddr_t *);

/* round up and down to page boundaries. */
#define ELF_ROUND(a, b)         (((a) + (b) - 1) & ~((b) - 1))
#define ELF_TRUNC(a, b)         ((a) & ~((b) - 1))

#define MAXPHNUM        50

#ifdef PAX_ASLR
/*
 * We don't move this code in kern_pax.c because it is compiled twice.
 */
static void
pax_aslr_elf(struct lwp *l, struct exec_package *epp, Elf_Ehdr *eh,
    Elf_Phdr *ph)
{
        size_t pax_align = 0, pax_offset, i;
        uint32_t r;

        if (!pax_aslr_active(l))
                return;

        /*
         * find align XXX: not all sections might have the same
         * alignment
         */
        for (i = 0; i < eh->e_phnum; i++)
                if (ph[i].p_type == PT_LOAD) {
                        pax_align = ph[i].p_align;
                        break;
                }

        r = arc4random();

        if (pax_align == 0)
                pax_align = PGSHIFT;
#ifdef DEBUG_ASLR
        uprintf("r=0x%x a=0x%x p=0x%x Delta=0x%lx\n", r,
            ilog2(pax_align), PGSHIFT, PAX_ASLR_DELTA(r,
                ilog2(pax_align), PAX_ASLR_DELTA_EXEC_LEN));
#endif
        pax_offset = ELF_TRUNC(PAX_ASLR_DELTA(r,
            ilog2(pax_align), PAX_ASLR_DELTA_EXEC_LEN), pax_align);

        for (i = 0; i < eh->e_phnum; i++)
                ph[i].p_vaddr += pax_offset;
        eh->e_entry += pax_offset;
#ifdef DEBUG_ASLR
        uprintf("pax offset=0x%zx entry=0x%llx\n",
            pax_offset, (unsigned long long)eh->e_entry);
#endif
}
#endif /* PAX_ASLR */

/*
 * Copy arguments onto the stack in the normal way, but add some
 * extra information in case of dynamic binding.
 */
int
elf_copyargs(struct lwp *l, struct exec_package *pack,
    struct ps_strings *arginfo, char **stackp, void *argp)
{
        size_t len, vlen;
        AuxInfo ai[ELF_AUX_ENTRIES], *a, *execname;
        struct elf_args *ap;
        int error;

        if ((error = copyargs(l, pack, arginfo, stackp, argp)) != 0)
                return error;

        a = ai;
        execname = NULL;

        /*
         * Push extra arguments on the stack needed by dynamically
         * linked binaries
         */
        if ((ap = (struct elf_args *)pack->ep_emul_arg)) {
                struct vattr *vap = pack->ep_vap;

                a->a_type = AT_PHDR;
                a->a_v = ap->arg_phaddr;
                a++;

                a->a_type = AT_PHENT;
                a->a_v = ap->arg_phentsize;
                a++;

                a->a_type = AT_PHNUM;
                a->a_v = ap->arg_phnum;
                a++;

                a->a_type = AT_PAGESZ;
                a->a_v = PAGE_SIZE;
                a++;

                a->a_type = AT_BASE;
                a->a_v = ap->arg_interp;
                a++;

                a->a_type = AT_FLAGS;
                a->a_v = 0;
                a++;

                a->a_type = AT_ENTRY;
                a->a_v = ap->arg_entry;
                a++;

                a->a_type = AT_EUID;
                if (vap->va_mode & S_ISUID)
                        a->a_v = vap->va_uid;
                else
                        a->a_v = kauth_cred_geteuid(l->l_cred);
                a++;

                a->a_type = AT_RUID;
                a->a_v = kauth_cred_getuid(l->l_cred);
                a++;

                a->a_type = AT_EGID;
                if (vap->va_mode & S_ISGID)
                        a->a_v = vap->va_gid;
                else
                        a->a_v = kauth_cred_getegid(l->l_cred);
                a++;

                a->a_type = AT_RGID;
                a->a_v = kauth_cred_getgid(l->l_cred);
                a++;

                if (pack->ep_path) {
                        execname = a;
                        a->a_type = AT_SUN_EXECNAME;
                        a++;
                }

                free(ap, M_TEMP);
                pack->ep_emul_arg = NULL;
        }

        a->a_type = AT_NULL;
        a->a_v = 0;
        a++;

        vlen = (a - ai) * sizeof(AuxInfo);

        if (execname) {
                char *path = pack->ep_path;
                execname->a_v = (uintptr_t)(*stackp + vlen);
                len = strlen(path) + 1;
                if ((error = copyout(path, (*stackp + vlen), len)) != 0)
                        return error;
                len = ALIGN(len);
        } else
                len = 0;

        if ((error = copyout(ai, *stackp, vlen)) != 0)
                return error;
        *stackp += vlen + len;

        return 0;
}

/*
 * elf_check_header():
 *
 * Check header for validity; return 0 of ok ENOEXEC if error
 */
int
elf_check_header(Elf_Ehdr *eh, int type)
{

        if (memcmp(eh->e_ident, ELFMAG, SELFMAG) != 0 ||
            eh->e_ident[EI_CLASS] != ELFCLASS)
                return ENOEXEC;

        switch (eh->e_machine) {

        ELFDEFNNAME(MACHDEP_ID_CASES)

        default:
                return ENOEXEC;
        }

        if (ELF_EHDR_FLAGS_OK(eh) == 0)
                return ENOEXEC;

        if (eh->e_type != type)
                return ENOEXEC;

        if (eh->e_shnum > 32768 || eh->e_phnum > 128)
                return ENOEXEC;

        return 0;
}

/*
 * elf_load_psection():
 *
 * Load a psection at the appropriate address
 */
void
elf_load_psection(struct exec_vmcmd_set *vcset, struct vnode *vp,
    const Elf_Phdr *ph, Elf_Addr *addr, u_long *size, int *prot, int flags)
{
        u_long msize, psize, rm, rf;
        long diff, offset;

        /*
         * If the user specified an address, then we load there.
         */
        if (*addr == ELFDEFNNAME(NO_ADDR))
                *addr = ph->p_vaddr;

        if (ph->p_align > 1) {
                /*
                 * Make sure we are virtually aligned as we are supposed to be.
                 */
                diff = ph->p_vaddr - ELF_TRUNC(ph->p_vaddr, ph->p_align);
                KASSERT(*addr - diff == ELF_TRUNC(*addr, ph->p_align));
                /*
                 * But make sure to not map any pages before the start of the
                 * psection by limiting the difference to within a page.
                 */
                diff &= PAGE_MASK;
        } else
                diff = 0;

        *prot |= (ph->p_flags & PF_R) ? VM_PROT_READ : 0;
        *prot |= (ph->p_flags & PF_W) ? VM_PROT_WRITE : 0;
        *prot |= (ph->p_flags & PF_X) ? VM_PROT_EXECUTE : 0;

        /*
         * Adjust everything so it all starts on a page boundary.
         */
        *addr -= diff;
        offset = ph->p_offset - diff;
        *size = ph->p_filesz + diff;
        msize = ph->p_memsz + diff;

        if (ph->p_align >= PAGE_SIZE) {
                if ((ph->p_flags & PF_W) != 0) {
                        /*
                         * Because the pagedvn pager can't handle zero fill
                         * of the last data page if it's not page aligned we
                         * map the last page readvn.
                         */
                        psize = trunc_page(*size);
                } else {
                        psize = round_page(*size);
                }
        } else {
                psize = *size;
        }

        if (psize > 0) {
                NEW_VMCMD2(vcset, ph->p_align < PAGE_SIZE ?
                    vmcmd_map_readvn : vmcmd_map_pagedvn, psize, *addr, vp,
                    offset, *prot, flags);
                flags &= VMCMD_RELATIVE;
        }
        if (psize < *size) {
                NEW_VMCMD2(vcset, vmcmd_map_readvn, *size - psize,
                    *addr + psize, vp, offset + psize, *prot, flags);
        }

        /*
         * Check if we need to extend the size of the segment (does
         * bss extend page the next page boundary)?
         */
        rm = round_page(*addr + msize);
        rf = round_page(*addr + *size);

        if (rm != rf) {
                NEW_VMCMD2(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP,
                    0, *prot, flags & VMCMD_RELATIVE);
                *size = msize;
        }
}

/*
 * elf_load_file():
 *
 * Load a file (interpreter/library) pointed to by path
 * [stolen from coff_load_shlib()]. Made slightly generic
 * so it might be used externally.
 */
int
elf_load_file(struct lwp *l, struct exec_package *epp, char *path,
    struct exec_vmcmd_set *vcset, u_long *entryoff, struct elf_args *ap,
    Elf_Addr *last)
{
        int error, i;
        struct vnode *vp;
        struct vattr attr;
        Elf_Ehdr eh;
        Elf_Phdr *ph = NULL;
        const Elf_Phdr *ph0;
        const Elf_Phdr *base_ph;
        const Elf_Phdr *last_ph;
        u_long phsize;
        Elf_Addr addr = *last;
        struct proc *p;

        p = l->l_proc;

        /*
         * 1. open file
         * 2. read filehdr
         * 3. map text, data, and bss out of it using VM_*
         */
        vp = epp->ep_interp;
        if (vp == NULL) {
                error = emul_find_interp(l, epp, path);
                if (error != 0)
                        return error;
                vp = epp->ep_interp;
        }
        /* We'll tidy this ourselves - otherwise we have locking issues */
        epp->ep_interp = NULL;
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);

        /*
         * Similarly, if it's not marked as executable, or it's not a regular
         * file, we don't allow it to be used.
         */
        if (vp->v_type != VREG) {
                error = EACCES;
                goto badunlock;
        }
        if ((error = VOP_ACCESS(vp, VEXEC, l->l_cred)) != 0)
                goto badunlock;

        /* get attributes */
        if ((error = VOP_GETATTR(vp, &attr, l->l_cred)) != 0)
                goto badunlock;

        /*
         * Check mount point.  Though we're not trying to exec this binary,
         * we will be executing code from it, so if the mount point
         * disallows execution or set-id-ness, we punt or kill the set-id.
         */
        if (vp->v_mount->mnt_flag & MNT_NOEXEC) {
                error = EACCES;
                goto badunlock;
        }
        if (vp->v_mount->mnt_flag & MNT_NOSUID)
                epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID);

#ifdef notyet /* XXX cgd 960926 */
        XXX cgd 960926: (maybe) VOP_OPEN it (and VOP_CLOSE in copyargs?)
#endif

        error = vn_marktext(vp);
        if (error)
                goto badunlock;

        VOP_UNLOCK(vp, 0);

        if ((error = exec_read_from(l, vp, 0, &eh, sizeof(eh))) != 0)
                goto bad;

        if ((error = elf_check_header(&eh, ET_DYN)) != 0)
                goto bad;

        if (eh.e_phnum > MAXPHNUM || eh.e_phnum == 0) {
                error = ENOEXEC;
                goto bad;
        }

        phsize = eh.e_phnum * sizeof(Elf_Phdr);
        ph = kmem_alloc(phsize, KM_SLEEP);

        if ((error = exec_read_from(l, vp, eh.e_phoff, ph, phsize)) != 0)
                goto bad;

#ifdef ELF_INTERP_NON_RELOCATABLE
        /*
         * Evil hack:  Only MIPS should be non-relocatable, and the
         * psections should have a high address (typically 0x5ffe0000).
         * If it's now relocatable, it should be linked at 0 and the
         * psections should have zeros in the upper part of the address.
         * Otherwise, force the load at the linked address.
         */
        if (*last == ELF_LINK_ADDR && (ph->p_vaddr & 0xffff0000) == 0)
                *last = ELFDEFNNAME(NO_ADDR);
#endif

        /*
         * If no position to load the interpreter was set by a probe
         * function, pick the same address that a non-fixed mmap(0, ..)
         * would (i.e. something safely out of the way).
         */
        if (*last == ELFDEFNNAME(NO_ADDR)) {
                u_long limit = 0;
                /*
                 * Find the start and ending addresses of the psections to
                 * be loaded.  This will give us the size.
                 */
                for (i = 0, ph0 = ph, base_ph = NULL; i < eh.e_phnum;
                     i++, ph0++) {
                        if (ph0->p_type == PT_LOAD) {
                                u_long psize = ph0->p_vaddr + ph0->p_memsz;
                                if (base_ph == NULL)
                                        base_ph = ph0;
                                if (psize > limit)
                                        limit = psize;
                        }
                }

                if (base_ph == NULL) {
                        error = ENOEXEC;
                        goto bad;
                }

                /*
                 * Now compute the size and load address.
                 */
                addr = (*epp->ep_esch->es_emul->e_vm_default_addr)(p,
                    epp->ep_daddr,
                    round_page(limit) - trunc_page(base_ph->p_vaddr));
        } else
                addr = *last; /* may be ELF_LINK_ADDR */

        /*
         * Load all the necessary sections
         */
        for (i = 0, ph0 = ph, base_ph = NULL, last_ph = NULL;
             i < eh.e_phnum; i++, ph0++) {
                switch (ph0->p_type) {
                case PT_LOAD: {
                        u_long size;
                        int prot = 0;
                        int flags;

                        if (base_ph == NULL) {
                                /*
                                 * First encountered psection is always the
                                 * base psection.  Make sure it's aligned
                                 * properly (align down for topdown and align
                                 * upwards for not topdown).
                                 */
                                base_ph = ph0;
                                flags = VMCMD_BASE;
                                if (addr == ELF_LINK_ADDR)
                                        addr = ph0->p_vaddr;
                                if (p->p_vmspace->vm_map.flags & VM_MAP_TOPDOWN)
                                        addr = ELF_TRUNC(addr, ph0->p_align);
                                else
                                        addr = ELF_ROUND(addr, ph0->p_align);
                        } else {
                                u_long limit = round_page(last_ph->p_vaddr
                                    + last_ph->p_memsz);
                                u_long base = trunc_page(ph0->p_vaddr);

                                /*
                                 * If there is a gap in between the psections,
                                 * map it as inaccessible so nothing else
                                 * mmap'ed will be placed there.
                                 */
                                if (limit != base) {
                                        NEW_VMCMD2(vcset, vmcmd_map_zero,
                                            base - limit,
                                            limit - base_ph->p_vaddr, NULLVP,
                                            0, VM_PROT_NONE, VMCMD_RELATIVE);
                                }

                                addr = ph0->p_vaddr - base_ph->p_vaddr;
                                flags = VMCMD_RELATIVE;
                        }
                        last_ph = ph0;
                        elf_load_psection(vcset, vp, &ph[i], &addr,
                            &size, &prot, flags);
                        /*
                         * If entry is within this psection then this
                         * must contain the .text section.  *entryoff is
                         * relative to the base psection.
                         */
                        if (eh.e_entry >= ph0->p_vaddr &&
                            eh.e_entry < (ph0->p_vaddr + size)) {
                                *entryoff = eh.e_entry - base_ph->p_vaddr;
                        }
                        addr += size;
                        break;
                }

                case PT_DYNAMIC:
                case PT_PHDR:
                        break;

                case PT_NOTE:
                        break;

                default:
                        break;
                }
        }

        kmem_free(ph, phsize);
        /*
         * This value is ignored if TOPDOWN.
         */
        *last = addr;
        vrele(vp);
        return 0;

badunlock:
        VOP_UNLOCK(vp, 0);

bad:
        if (ph != NULL)
                kmem_free(ph, phsize);
#ifdef notyet /* XXX cgd 960926 */
        (maybe) VOP_CLOSE it
#endif
        vrele(vp);
        return error;
}

/*
 * exec_elf_makecmds(): Prepare an Elf binary's exec package
 *
 * First, set of the various offsets/lengths in the exec package.
 *
 * Then, mark the text image busy (so it can be demand paged) or error
 * out if this is not possible.  Finally, set up vmcmds for the
 * text, data, bss, and stack segments.
 */
int
exec_elf_makecmds(struct lwp *l, struct exec_package *epp)
{
        Elf_Ehdr *eh = epp->ep_hdr;
        Elf_Phdr *ph, *pp;
        Elf_Addr phdr = 0, pos = 0;
        int error, i, nload;
        char *interp = NULL;
        u_long phsize;
        struct proc *p;
        bool is_dyn;

        if (epp->ep_hdrvalid < sizeof(Elf_Ehdr))
                return ENOEXEC;

        is_dyn = elf_check_header(eh, ET_DYN) == 0;
        /*
         * XXX allow for executing shared objects. It seems silly
         * but other ELF-based systems allow it as well.
         */
        if (elf_check_header(eh, ET_EXEC) != 0 && !is_dyn)
                return ENOEXEC;

        if (eh->e_phnum > MAXPHNUM || eh->e_phnum == 0)
                return ENOEXEC;

        error = vn_marktext(epp->ep_vp);
        if (error)
                return error;

        /*
         * Allocate space to hold all the program headers, and read them
         * from the file
         */
        p = l->l_proc;
        phsize = eh->e_phnum * sizeof(Elf_Phdr);
        ph = kmem_alloc(phsize, KM_SLEEP);

        if ((error = exec_read_from(l, epp->ep_vp, eh->e_phoff, ph, phsize)) !=
            0)
                goto bad;

        epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR);
        epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR);

        for (i = 0; i < eh->e_phnum; i++) {
                pp = &ph[i];
                if (pp->p_type == PT_INTERP) {
                        if (pp->p_filesz >= MAXPATHLEN) {
                                error = ENOEXEC;
                                goto bad;
                        }
                        interp = PNBUF_GET();
                        interp[0] = '\0';
                        if ((error = exec_read_from(l, epp->ep_vp,
                            pp->p_offset, interp, pp->p_filesz)) != 0)
                                goto bad;
                        break;
                }
        }

        /*
         * On the same architecture, we may be emulating different systems.
         * See which one will accept this executable.
         *
         * Probe functions would normally see if the interpreter (if any)
         * exists. Emulation packages may possibly replace the interpreter in
         * interp[] with a changed path (/emul/xxx/<path>).
         */
        pos = ELFDEFNNAME(NO_ADDR);
        if (epp->ep_esch->u.elf_probe_func) {
                vaddr_t startp = (vaddr_t)pos;

                error = (*epp->ep_esch->u.elf_probe_func)(l, epp, eh, interp,
                                                          &startp);
                if (error)
                        goto bad;
                pos = (Elf_Addr)startp;
        }

#if defined(PAX_MPROTECT) || defined(PAX_SEGVGUARD) || defined(PAX_ASLR)
        p->p_pax = epp->ep_pax_flags;
#endif /* PAX_MPROTECT || PAX_SEGVGUARD || PAX_ASLR */

#ifdef PAX_ASLR
        if (is_dyn)
                pax_aslr_elf(l, epp, eh, ph);
#endif /* PAX_ASLR */

        /*
         * Load all the necessary sections
         */
        for (i = nload = 0; i < eh->e_phnum; i++) {
                Elf_Addr  addr = ELFDEFNNAME(NO_ADDR);
                u_long size = 0;
                int prot = 0;

                pp = &ph[i];

                switch (ph[i].p_type) {
                case PT_LOAD:
                        /*
                         * XXX
                         * Can handle only 2 sections: text and data
                         */
                        if (nload++ == 2) {
                                error = ENOEXEC;
                                goto bad;
                        }
                        elf_load_psection(&epp->ep_vmcmds, epp->ep_vp,
                            &ph[i], &addr, &size, &prot, VMCMD_FIXED);

                        /*
                         * Decide whether it's text or data by looking
                         * at the entry point.
                         */
                        if (eh->e_entry >= addr &&
                            eh->e_entry < (addr + size)) {
                                epp->ep_taddr = addr;
                                epp->ep_tsize = size;
                                if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) {
                                        epp->ep_daddr = addr;
                                        epp->ep_dsize = size;
                                }
                        } else {
                                epp->ep_daddr = addr;
                                epp->ep_dsize = size;
                        }
                        break;

                case PT_SHLIB:
                        /* SCO has these sections. */
                case PT_INTERP:
                        /* Already did this one. */
                case PT_DYNAMIC:
                        break;
                case PT_NOTE:
                        break;
                case PT_PHDR:
                        /* Note address of program headers (in text segment) */
                        phdr = pp->p_vaddr;
                        break;

                default:
                        /*
                         * Not fatal; we don't need to understand everything.
                         */
                        break;
                }
        }

        /*
         * Check if we found a dynamically linked binary and arrange to load
         * its interpreter
         */
        if (interp) {
                struct elf_args *ap;
                int j = epp->ep_vmcmds.evs_used;
                u_long interp_offset;

                ap = (struct elf_args *)malloc(sizeof(struct elf_args),
                    M_TEMP, M_WAITOK);
                if ((error = elf_load_file(l, epp, interp,
                    &epp->ep_vmcmds, &interp_offset, ap, &pos)) != 0) {
                        free(ap, M_TEMP);
                        goto bad;
                }
                ap->arg_interp = epp->ep_vmcmds.evs_cmds[j].ev_addr;
                epp->ep_entry = ap->arg_interp + interp_offset;
                ap->arg_phaddr = phdr;

                ap->arg_phentsize = eh->e_phentsize;
                ap->arg_phnum = eh->e_phnum;
                ap->arg_entry = eh->e_entry;

                epp->ep_emul_arg = ap;

                PNBUF_PUT(interp);
        } else
                epp->ep_entry = eh->e_entry;

#ifdef ELF_MAP_PAGE_ZERO
        /* Dell SVR4 maps page zero, yeuch! */
        NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, PAGE_SIZE, 0,
            epp->ep_vp, 0, VM_PROT_READ);
#endif
        kmem_free(ph, phsize);
        return (*epp->ep_esch->es_setup_stack)(l, epp);

bad:
        if (interp)
                PNBUF_PUT(interp);
        kmem_free(ph, phsize);
        kill_vmcmds(&epp->ep_vmcmds);
        return error;
}

int
netbsd_elf_signature(struct lwp *l, struct exec_package *epp,
    Elf_Ehdr *eh)
{
        size_t i;
        Elf_Phdr *ph;
        size_t phsize;
        int error;
        int isnetbsd = 0;
        char *ndata;

        epp->ep_pax_flags = 0;
        if (eh->e_phnum > MAXPHNUM || eh->e_phnum == 0)
                return ENOEXEC;

        phsize = eh->e_phnum * sizeof(Elf_Phdr);
        ph = kmem_alloc(phsize, KM_SLEEP);
        error = exec_read_from(l, epp->ep_vp, eh->e_phoff, ph, phsize);
        if (error)
                goto out;

        for (i = 0; i < eh->e_phnum; i++) {
                Elf_Phdr *ephp = &ph[i];
                Elf_Nhdr *np;

                if (ephp->p_type != PT_NOTE ||
                    ephp->p_filesz > 1024 ||
                    ephp->p_filesz < sizeof(Elf_Nhdr) + ELF_NOTE_NETBSD_NAMESZ)
                        continue;

                np = kmem_alloc(ephp->p_filesz, KM_SLEEP);
                error = exec_read_from(l, epp->ep_vp, ephp->p_offset, np,
                    ephp->p_filesz);
                if (error)
                        goto next;

                ndata = (char *)(np + 1);
                switch (np->n_type) {
                case ELF_NOTE_TYPE_NETBSD_TAG:
                        if (np->n_namesz != ELF_NOTE_NETBSD_NAMESZ ||
                            np->n_descsz != ELF_NOTE_NETBSD_DESCSZ ||
                            memcmp(ndata, ELF_NOTE_NETBSD_NAME,
                            ELF_NOTE_NETBSD_NAMESZ))
                                goto next;
                        isnetbsd = 1;
                        break;

                case ELF_NOTE_TYPE_PAX_TAG:
                        if (np->n_namesz != ELF_NOTE_PAX_NAMESZ ||
                            np->n_descsz != ELF_NOTE_PAX_DESCSZ ||
                            memcmp(ndata, ELF_NOTE_PAX_NAME,
                            ELF_NOTE_PAX_NAMESZ))
                                goto next;
                        (void)memcpy(&epp->ep_pax_flags,
                            ndata + ELF_NOTE_PAX_NAMESZ,
                            sizeof(epp->ep_pax_flags));
                        break;

                default:
                        break;
                }

next:
                kmem_free(np, ephp->p_filesz);
                continue;
        }

        error = isnetbsd ? 0 : ENOEXEC;
out:
        kmem_free(ph, phsize);
        return error;
}

int
netbsd_elf_probe(struct lwp *l, struct exec_package *epp, void *eh, char *itp,
    vaddr_t *pos)
{
        int error;

        if ((error = netbsd_elf_signature(l, epp, eh)) != 0)
                return error;
#ifdef ELF_MD_PROBE_FUNC
        if ((error = ELF_MD_PROBE_FUNC(l, epp, eh, itp, pos)) != 0)
                return error;
#elif defined(ELF_INTERP_NON_RELOCATABLE)
        *pos = ELF_LINK_ADDR;
#endif
        return 0;
}