/*      $OpenBSD: library_mquery.c,v 1.76 2024/04/05 13:51:47 deraadt Exp $ */

/*
 * Copyright (c) 2002 Dale Rahn
 * 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.
 *
 */

#define _DYN_LOADER

#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>

#include "syscall.h"
#include "util.h"
#include "archdep.h"
#include "resolve.h"
#include "sod.h"

#define PFLAGS(X) ((((X) & PF_R) ? PROT_READ : 0) | \
                   (((X) & PF_W) ? PROT_WRITE : 0) | \
                   (((X) & PF_X) ? PROT_EXEC : 0))

void
_dl_load_list_free(struct load_list *load_list)
{
        struct load_list *next;
        Elf_Addr align = _dl_pagesz - 1;

        while (load_list != NULL) {
                if (load_list->start != NULL)
                        _dl_munmap(load_list->start,
                            ((load_list->size) + align) & ~align);
                next = load_list->next;
                _dl_free(load_list);
                load_list = next;
        }
}

void
_dl_unload_shlib(elf_object_t *object)
{
        struct dep_node *n;
        elf_object_t *load_object = object->load_object;

        /*
         * If our load object has become unreferenced then we lost the
         * last group reference to it, so the entire group should be taken
         * down.  The current object is somewhere below load_object in
         * the child_vec tree, so it'll get cleaned up by the recursion.
         * That means we can just switch here to the load object.
         */
        if (load_object != object && OBJECT_REF_CNT(load_object) == 0 &&
            (load_object->status & STAT_UNLOADED) == 0) {
                DL_DEB(("unload_shlib switched from %s to %s\n",
                    object->load_name, load_object->load_name));
                object = load_object;
                goto unload;
        }

        DL_DEB(("unload_shlib called on %s\n", object->load_name));
        if (OBJECT_REF_CNT(object) == 0 &&
            (object->status & STAT_UNLOADED) == 0) {
                struct object_vector vec;
                int i;
unload:
                object->status |= STAT_UNLOADED;
                for (vec = object->child_vec, i = 0; i < vec.len; i++)
                        _dl_unload_shlib(vec.vec[i]);
                TAILQ_FOREACH(n, &object->grpref_list, next_sib)
                        _dl_unload_shlib(n->data);
                DL_DEB(("unload_shlib unloading on %s\n", object->load_name));
                _dl_load_list_free(object->load_list);
                _dl_remove_object(object);
        }
}

elf_object_t *
_dl_tryload_shlib(const char *libname, int type, int flags, int nodelete)
{
        struct range_vector imut, mut;
        int libfile, libc = -1, i;
        struct load_list *ld, *lowld = NULL;
        elf_object_t *object;
        Elf_Dyn *dynp = NULL;
        Elf_Ehdr *ehdr;
        Elf_Phdr *phdp, *ptls = NULL;
        Elf_Phdr *syscall_phdp = NULL;
        Elf_Addr load_end = 0;
        Elf_Addr align = _dl_pagesz - 1, off, size;
        Elf_Addr relro_addr = 0, relro_size = 0;
        struct stat sb;
        char hbuf[4096], *exec_start;
        size_t exec_size;

#define powerof2(x) ((((x) - 1) & (x)) == 0)
#define ROUND_PG(x) (((x) + align) & ~(align))
#define TRUNC_PG(x) ((x) & ~(align))

        libfile = _dl_open(libname, O_RDONLY | O_CLOEXEC);
        if (libfile < 0) {
                _dl_errno = DL_CANT_OPEN;
                return(0);
        }

        if (_dl_fstat(libfile, &sb) < 0) {
                _dl_errno = DL_CANT_OPEN;
                return(0);
        }

        for (object = _dl_objects; object != NULL; object = object->next) {
                if (object->dev == sb.st_dev &&
                    object->inode == sb.st_ino) {
                        _dl_close(libfile);
                        _dl_handle_already_loaded(object, flags);
                        return(object);
                }
        }
        if (flags & DF_1_NOOPEN) {
                _dl_close(libfile);
                return NULL;
        }

        _dl_read(libfile, hbuf, sizeof(hbuf));
        ehdr = (Elf_Ehdr *)hbuf;
        if (ehdr->e_ident[0] != ELFMAG0  || ehdr->e_ident[1] != ELFMAG1 ||
            ehdr->e_ident[2] != ELFMAG2 || ehdr->e_ident[3] != ELFMAG3 ||
            ehdr->e_type != ET_DYN || ehdr->e_machine != MACHID) {
                _dl_close(libfile);
                _dl_errno = DL_NOT_ELF;
                return(0);
        }

        /* Insertion sort */
#define LDLIST_INSERT(ld) do { \
        struct load_list **_ld; \
        for (_ld = &lowld; *_ld != NULL; _ld = &(*_ld)->next) \
                if ((*_ld)->moff > ld->moff) \
                        break; \
        ld->next = *_ld; \
        *_ld = ld; \
} while (0)
        /*
         *  Alright, we might have a winner!
         *  Figure out how much VM space we need and set up the load
         *  list that we'll use to find free VM space.
         */
        phdp = (Elf_Phdr *)(hbuf + ehdr->e_phoff);
        for (i = 0; i < ehdr->e_phnum; i++, phdp++) {
                if (phdp->p_align > 1 && !powerof2(phdp->p_align)) {
                        _dl_printf("%s: ld.so invalid ELF input %s.\n",
                            __progname, libname);
                        _dl_close(libfile);
                        _dl_errno = DL_CANT_MMAP;
                        return(0);
                }

                switch (phdp->p_type) {
                case PT_LOAD:
                        off = (phdp->p_vaddr & align);
                        size = off + phdp->p_filesz;

                        if (size != 0) {
                                ld = _dl_malloc(sizeof(struct load_list));
                                if (ld == NULL)
                                        _dl_oom();
                                ld->start = NULL;
                                ld->size = size;
                                ld->moff = TRUNC_PG(phdp->p_vaddr);
                                ld->foff = TRUNC_PG(phdp->p_offset);
                                ld->prot = PFLAGS(phdp->p_flags);
                                LDLIST_INSERT(ld);
                        }

                        if ((PFLAGS(phdp->p_flags) & PROT_WRITE) == 0 ||
                            ROUND_PG(size) == ROUND_PG(off + phdp->p_memsz))
                                break;
                        /* This phdr has a zfod section */
                        ld = _dl_calloc(1, sizeof(struct load_list));
                        if (ld == NULL)
                                _dl_oom();
                        ld->start = NULL;
                        ld->size = ROUND_PG(off + phdp->p_memsz) -
                            ROUND_PG(size);
                        ld->moff = TRUNC_PG(phdp->p_vaddr) +
                            ROUND_PG(size);
                        ld->foff = -1;
                        ld->prot = PFLAGS(phdp->p_flags);
                        LDLIST_INSERT(ld);
                        break;
                case PT_DYNAMIC:
                        dynp = (Elf_Dyn *)phdp->p_vaddr;
                        break;
                case PT_TLS:
                        if (phdp->p_filesz > phdp->p_memsz) {
                                _dl_printf("%s: invalid tls data in %s.\n",
                                    __progname, libname);
                                _dl_close(libfile);
                                _dl_errno = DL_CANT_LOAD_OBJ;
                                return(0);
                        }
                        if (!_dl_tib_static_done) {
                                ptls = phdp;
                                break;
                        }
                        _dl_printf("%s: unsupported TLS program header in %s\n",
                            __progname, libname);
                        _dl_close(libfile);
                        _dl_errno = DL_CANT_LOAD_OBJ;
                        return(0);
                default:
                        break;
                }
        }

#define LOFF ((Elf_Addr)lowld->start - lowld->moff)

retry:
        _dl_memset(&mut, 0, sizeof mut);
        _dl_memset(&imut, 0, sizeof imut);
        exec_start = NULL;
        exec_size = 0;
        for (ld = lowld; ld != NULL; ld = ld->next) {
                off_t foff;
                int fd, flags;
                void *res;

                flags = MAP_PRIVATE;

                if (ld->foff < 0) {
                        fd = -1;
                        foff = 0;
                        flags |= MAP_ANON;
                } else {
                        fd = libfile;
                        foff = ld->foff;
                }

                if (ld == lowld) {
                        /*
                         * Add PROT_EXEC to force the first allocation in
                         * EXEC region unless it is writable.
                         */
                        int exec = (ld->prot & PROT_WRITE) ? 0 : PROT_EXEC;
                        if (exec && lowld->start == NULL)
                                lowld->start = _dl_exec_hint;
                        res = _dl_mquery((void *)(LOFF + ld->moff),
                            ROUND_PG(ld->size), ld->prot | exec, flags,
                            fd, foff);
                        if (_dl_mmap_error(res))
                                goto fail;
                        lowld->start = res;
                }

                res = _dl_mmap((void *)(LOFF + ld->moff), ROUND_PG(ld->size),
                    ld->prot, flags | MAP_FIXED | __MAP_NOREPLACE, fd, foff);
                if (_dl_mmap_error(res)) {
                        struct load_list *ll;

                        /* Unmap any mappings that we did get in. */
                        for (ll = lowld; ll != NULL && ll != ld;
                             ll = ll->next) {
                                _dl_munmap(ll->start, ROUND_PG(ll->size));
                        }

                        lowld->start += ROUND_PG(ld->size);
                        goto retry;
                }

                if ((ld->prot & PROT_EXEC) && exec_start == NULL) {
                        exec_start = (void *)(LOFF + ld->moff);
                        exec_size = ROUND_PG(ld->size);
                }

                /* Entire mapping can become immutable, minus exceptions chosen later */
                _dl_push_range_size(&imut, LOFF + ld->moff, ROUND_PG(ld->size));

                ld->start = res;
        }

        for (ld = lowld; ld != NULL; ld = ld->next) {
                /* Zero out everything past the EOF */
                if ((ld->prot & PROT_WRITE) != 0 && (ld->size & align) != 0)
                        _dl_memset((char *)ld->start + ld->size, 0,
                            _dl_pagesz - (ld->size & align));
                load_end = (Elf_Addr)ld->start + ROUND_PG(ld->size);
        }

        phdp = (Elf_Phdr *)(hbuf + ehdr->e_phoff);
        for (i = 0; i < ehdr->e_phnum; i++, phdp++) {
                switch (phdp->p_type) {
                case PT_OPENBSD_RANDOMIZE:
                        _dl_arc4randombuf((char *)(phdp->p_vaddr + LOFF),
                            phdp->p_memsz);
                        break;
                case PT_GNU_RELRO:
                        relro_addr = phdp->p_vaddr + LOFF;
                        relro_size = phdp->p_memsz;
                        _dl_push_range_size(&mut, relro_addr, relro_size);
                        break;
                case PT_OPENBSD_MUTABLE:
                        _dl_push_range_size(&mut, phdp->p_vaddr + LOFF,
                            phdp->p_memsz);
                        break;
                case PT_OPENBSD_SYSCALLS:
                        syscall_phdp = phdp;
                        break;
                }
        }

        libc = _dl_islibc(dynp, LOFF);
        if (libc && syscall_phdp)
                _dl_pin(libfile, syscall_phdp, lowld->start,
                    (size_t)((exec_start + exec_size) - LOFF),
                    exec_start, exec_size);
        _dl_close(libfile);

        dynp = (Elf_Dyn *)((unsigned long)dynp + LOFF);
        object = _dl_finalize_object(libname, dynp,
            (Elf_Phdr *)((char *)lowld->start + ehdr->e_phoff), ehdr->e_phnum,
            type, (Elf_Addr)lowld->start, LOFF);
        if (object) {
                object->load_size = (Elf_Addr)load_end - (Elf_Addr)lowld->start;
                object->load_list = lowld;
                /* set inode, dev from stat info */
                object->dev = sb.st_dev;
                object->inode = sb.st_ino;
                object->obj_flags |= flags;
                object->nodelete = nodelete;
                object->relro_addr = relro_addr;
                object->relro_size = relro_size;
                object->islibc = libc;
                _dl_set_sod(object->load_name, &object->sod);
                if (ptls != NULL && ptls->p_memsz)
                        _dl_set_tls(object, ptls, (Elf_Addr)lowld->start,
                            libname);
                _dl_bcopy(&mut, &object->mut, sizeof mut);
                _dl_bcopy(&imut, &object->imut, sizeof imut);
        } else {
                _dl_load_list_free(lowld);
        }
        return(object);
fail:
        _dl_printf("%s: ld.so mmap failed mapping %s.\n", __progname, libname);
        _dl_close(libfile);
        _dl_errno = DL_CANT_MMAP;
        _dl_load_list_free(lowld);
        return(0);
}