/*      $OpenBSD: boot.h,v 1.35 2023/11/18 16:26:15 deraadt Exp $ */

/*
 * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
 *
 * 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 ``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.
 *
 */

/*
 * IMPORTANT: any functions below are NOT protected by SSP.  Please
 * do not add anything except what is required to reach GOT with
 * an adjustment.
 */

#define _DYN_LOADER

#include <sys/exec_elf.h>
#include <sys/mman.h>

#include <machine/reloc.h>

__dead
void _csu_abort(void);

#include "archdep.h"

/*
 * Use the internal, hidden name for any syscalls we need, to avoid
 * accidental override by application code
 */
#define REDIRECT_SYSCALL(x)     typeof(x) x asm("_libc_"#x) __dso_hidden
REDIRECT_SYSCALL(mprotect);
REDIRECT_SYSCALL(mimmutable);

#if RELOC_TAG == DT_RELA
typedef Elf_RelA        RELOC_TYPE;
#elif RELOC_TAG == DT_REL
typedef Elf_Rel         RELOC_TYPE;
#else
# error "unknown RELOC_TAG"
#endif

static void *relro_addr;
static size_t relro_size;
#define RCRT0_RELRO()                                                   \
        do {                                                            \
                if (relro_addr != NULL && relro_size != 0) {            \
                        mprotect(relro_addr, relro_size, PROT_READ);    \
                        mimmutable(relro_addr, relro_size);             \
                }                                                       \
        } while (0)

/*
 * Local decls.
 */
void _dl_boot_bind(const long, long *, Elf_Dyn *);

void
_dl_boot_bind(const long sp, long *dl_data, Elf_Dyn *dynp)
{
        AuxInfo         *auxstack;
        long            *stack;
        int             n, argc;
        char            **argv, **envp;
        long            loff;
        RELOC_TYPE      *dt_reloc, *rend;       /* DT_RELA   or DT_REL */
        Elf_Word        dt_relocsz;             /* DT_RELASZ or DT_RELSZ */
        const Elf_Sym   *dt_symtab;
        Elf_Phdr        *phdp;
        Elf_Addr        i;

        /*
         * Scan argument and environment vectors. Find dynamic
         * data vector put after them.
         */
        stack = (long *)sp;
        argc = *stack++;
        argv = (char **)stack;
        envp = &argv[argc + 1];
        stack = (long *)envp;
        while (*stack++ != 0L)
                ;

        /*
         * Zero out dl_data.
         */
        for (n = 0; n <= AUX_entry; n++)
                dl_data[n] = 0;

        /*
         * Dig out auxiliary data set up by exec call. Move all known
         * tags to an indexed local table for easy access.
         */
        for (auxstack = (AuxInfo *)stack; auxstack->au_id != AUX_null;
            auxstack++) {
                if (auxstack->au_id > AUX_entry)
                        continue;
                dl_data[auxstack->au_id] = auxstack->au_v;
        }
        loff = dl_data[AUX_base];       /* XXX assumes ld.so is linked at 0x0 */

        /*
         * Scan the DYNAMIC section for the items we need
         */
        dt_reloc = NULL;
        dt_relocsz = 0;
        while (dynp->d_tag != DT_NULL) {
                /* first the tags that are pointers to be relocated */
                if (dynp->d_tag == DT_SYMTAB)
                        dt_symtab = (void *)(dynp->d_un.d_ptr + loff);
                else if (dynp->d_tag == RELOC_TAG)      /* DT_{RELA,REL} */
                        dt_reloc = (void *)(dynp->d_un.d_ptr + loff);

                /* Now for the tags that are just sizes or counts */
                else if (dynp->d_tag == RELOC_TAG+1)    /* DT_{RELA,REL}SZ */
                        dt_relocsz = dynp->d_un.d_val;
                dynp++;
        }

        rend = (RELOC_TYPE *)((char *)dt_reloc + dt_relocsz);
        for (; dt_reloc < rend; dt_reloc++) {
                Elf_Addr *ra;
                const Elf_Sym *sp;

                sp = dt_symtab + ELF_R_SYM(dt_reloc->r_info);
                if (!ELF_R_SYM(dt_reloc->r_info) || sp->st_value != 0) {
                        ra = (Elf_Addr *)(dt_reloc->r_offset + loff);
                        RELOC_DYN(dt_reloc, sp, ra, loff);
                }
        }

        /* do any RWX -> RX fixups for executable PLTs and apply GNU_RELRO */
        phdp = (Elf_Phdr *)dl_data[AUX_phdr];
        for (i = 0; i < dl_data[AUX_phnum]; i++, phdp++) {
                switch (phdp->p_type) {
#if defined(__alpha__) || defined(__powerpc__) || defined(__sparc64__)
                case PT_LOAD:
                        if ((phdp->p_flags & (PF_X | PF_W)) != (PF_X | PF_W))
                                break;
                        mprotect((void *)(phdp->p_vaddr + loff), phdp->p_memsz,
                            PROT_READ);
                        break;
#endif
                case PT_GNU_RELRO:
                        relro_addr = (void *)(phdp->p_vaddr + loff);
                        relro_size = phdp->p_memsz;
                        /*
                         * GNU_RELRO (a) covers the GOT, and (b) comes after
                         * all LOAD sections, so if we found it then we're done
                         */
                        break;
                }
        }
}