315 lines
7.4 KiB
C
315 lines
7.4 KiB
C
#define _SYSTEM 1
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#include <minix/type.h>
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#include <minix/const.h>
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#include <minix/com.h>
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#include <minix/syslib.h>
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#include <sys/param.h>
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#include <sys/mman.h>
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#include <assert.h>
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#include <unistd.h>
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#include <errno.h>
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#include <libexec.h>
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#include <string.h>
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#include <machine/elf.h>
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#include <machine/vmparam.h>
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#include <machine/memory.h>
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#include <minix/syslib.h>
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/* For verbose logging */
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#define ELF_DEBUG 0
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/* Support only 32-bit ELF objects */
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#define __ELF_WORD_SIZE 32
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#define SECTOR_SIZE 512
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static int check_header(Elf_Ehdr *hdr);
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static int elf_sane(Elf_Ehdr *hdr)
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{
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if (check_header(hdr) != OK) {
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return 0;
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}
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if((hdr->e_type != ET_EXEC) && (hdr->e_type != ET_DYN)) {
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return 0;
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}
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if ((hdr->e_phoff > SECTOR_SIZE) ||
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(hdr->e_phoff + hdr->e_phentsize * hdr->e_phnum) > SECTOR_SIZE) {
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#if ELF_DEBUG
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printf("peculiar phoff\n");
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#endif
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return 0;
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}
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return 1;
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}
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static int elf_ph_sane(Elf_Phdr *phdr)
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{
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if (rounddown((uintptr_t)phdr, sizeof(Elf_Addr)) != (uintptr_t)phdr) {
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return 0;
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}
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return 1;
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}
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static int elf_unpack(char *exec_hdr,
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size_t hdr_len, Elf_Ehdr **hdr, Elf_Phdr **phdr)
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{
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if(hdr_len < sizeof(Elf_Ehdr))
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return ENOEXEC;
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*hdr = (Elf_Ehdr *) exec_hdr;
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if(!elf_sane(*hdr)) {
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return ENOEXEC;
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}
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*phdr = (Elf_Phdr *)(exec_hdr + (*hdr)->e_phoff);
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if(!elf_ph_sane(*phdr)) {
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return ENOEXEC;
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}
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#if 0
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if((int)((*phdr) + (*hdr)->e_phnum) >= hdr_len) return ENOEXEC;
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#endif
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return OK;
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}
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#define IS_ELF(ehdr) ((ehdr).e_ident[EI_MAG0] == ELFMAG0 && \
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(ehdr).e_ident[EI_MAG1] == ELFMAG1 && \
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(ehdr).e_ident[EI_MAG2] == ELFMAG2 && \
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(ehdr).e_ident[EI_MAG3] == ELFMAG3)
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static int check_header(Elf_Ehdr *hdr)
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{
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if (!IS_ELF(*hdr) ||
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hdr->e_ident[EI_DATA] != ELF_TARG_DATA ||
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hdr->e_ident[EI_VERSION] != EV_CURRENT ||
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hdr->e_phentsize != sizeof(Elf_Phdr) ||
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hdr->e_version != ELF_TARG_VER)
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return ENOEXEC;
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return OK;
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}
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/* Return >0 if there is an ELF interpreter (i.e. it is a dynamically linked
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* executable) and we could extract it successfully.
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* Return 0 if there isn't one.
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* Return <0 on error.
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*/
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int elf_has_interpreter(char *exec_hdr, /* executable header */
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size_t hdr_len, char *interp, size_t maxsz)
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{
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Elf_Ehdr *hdr = NULL;
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Elf_Phdr *phdr = NULL;
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int e, i;
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if((e=elf_unpack(exec_hdr, hdr_len, &hdr, &phdr)) != OK) return 0;
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for (i = 0; i < hdr->e_phnum; i++) {
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switch (phdr[i].p_type) {
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case PT_INTERP:
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if(!interp) return 1;
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if(phdr[i].p_filesz >= maxsz)
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return -1;
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if(phdr[i].p_offset + phdr[i].p_filesz >= hdr_len)
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return -1;
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memcpy(interp, exec_hdr + phdr[i].p_offset, phdr[i].p_filesz);
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interp[phdr[i].p_filesz] = '\0';
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return 1;
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default:
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continue;
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}
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}
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return 0;
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}
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int libexec_load_elf(struct exec_info *execi)
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{
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Elf_Ehdr *hdr = NULL;
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Elf_Phdr *phdr = NULL;
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int e, i = 0;
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int first = 1;
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vir_bytes startv = 0, stacklow;
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assert(execi != NULL);
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assert(execi->hdr != NULL);
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if((e=elf_unpack(execi->hdr, execi->hdr_len, &hdr, &phdr)) != OK) {
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return e;
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}
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/* this function can load the dynamic linker, but that
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* shouldn't require an interpreter itself.
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*/
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i = elf_has_interpreter(execi->hdr, execi->hdr_len, NULL, 0);
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if(i > 0) {
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return ENOEXEC;
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}
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execi->stack_size = roundup(execi->stack_size, PAGE_SIZE);
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execi->stack_high = rounddown(execi->stack_high, PAGE_SIZE);
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stacklow = execi->stack_high - execi->stack_size;
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assert(execi->copymem);
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assert(execi->clearmem);
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assert(execi->allocmem_prealloc_cleared);
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assert(execi->allocmem_prealloc_junk);
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assert(execi->allocmem_ondemand);
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for (i = 0; i < hdr->e_phnum; i++) {
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Elf_Phdr *ph = &phdr[i];
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off_t file_limit = ph->p_offset + ph->p_filesz;
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/* sanity check binary before wiping out the target process */
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if(execi->filesize < file_limit) {
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return ENOEXEC;
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}
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}
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if(execi->clearproc) execi->clearproc(execi);
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for (i = 0; i < hdr->e_phnum; i++) {
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vir_bytes seg_membytes, page_offset, p_vaddr, vaddr;
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vir_bytes chunk, vfileend, vmemend;
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off_t foffset, fbytes;
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Elf_Phdr *ph = &phdr[i];
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int try_mmap = 1;
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u16_t clearend = 0;
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int pagechunk;
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int mmap_prot = PROT_READ;
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if(!(ph->p_flags & PF_R)) {
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printf("libexec: warning: unreadable segment\n");
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}
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if(ph->p_flags & PF_W) {
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mmap_prot |= PROT_WRITE;
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#if ELF_DEBUG
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printf("libexec: adding PROT_WRITE\n");
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#endif
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} else {
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#if ELF_DEBUG
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printf("libexec: not adding PROT_WRITE\n");
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#endif
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}
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if (ph->p_type != PT_LOAD || ph->p_memsz == 0) continue;
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if((ph->p_vaddr % PAGE_SIZE) != (ph->p_offset % PAGE_SIZE)) {
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printf("libexec: unaligned ELF program?\n");
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try_mmap = 0;
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}
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if(!execi->memmap) {
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try_mmap = 0;
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}
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foffset = ph->p_offset;
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fbytes = ph->p_filesz;
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vaddr = p_vaddr = ph->p_vaddr + execi->load_offset;
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seg_membytes = ph->p_memsz;
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page_offset = vaddr % PAGE_SIZE;
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vaddr -= page_offset;
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foffset -= page_offset;
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seg_membytes += page_offset;
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fbytes += page_offset;
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vfileend = p_vaddr + ph->p_filesz;
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/* if there's usable memory after the file end, we have
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* to tell VM to clear the memory part of the page when it's
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* mapped in
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*/
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if((pagechunk = (vfileend % PAGE_SIZE))
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&& ph->p_filesz < ph->p_memsz) {
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clearend = PAGE_SIZE - pagechunk;
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}
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seg_membytes = roundup(seg_membytes, PAGE_SIZE);
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fbytes = roundup(fbytes, PAGE_SIZE);
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if(first || startv > vaddr) startv = vaddr;
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first = 0;
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if ((ph->p_flags & PF_X) != 0 && execi->text_size < seg_membytes)
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execi->text_size = seg_membytes;
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else
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execi->data_size = seg_membytes;
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if(try_mmap && execi->memmap(execi, vaddr, fbytes, foffset, clearend, mmap_prot) == OK) {
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#if ELF_DEBUG
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printf("libexec: mmap 0x%lx-0x%lx done, clearend 0x%x\n",
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vaddr, vaddr+fbytes, clearend);
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#endif
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if(seg_membytes > fbytes) {
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int rem_mem = seg_membytes - fbytes;;
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vir_bytes remstart = vaddr + fbytes;
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if(execi->allocmem_ondemand(execi,
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remstart, rem_mem) != OK) {
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printf("libexec: mmap extra mem failed\n");
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return ENOMEM;
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}
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#if ELF_DEBUG
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else printf("libexec: allocated 0x%lx-0x%lx\n",
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remstart, remstart+rem_mem);
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#endif
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}
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} else {
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/* make us some memory */
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if(execi->allocmem_prealloc_junk(execi, vaddr, seg_membytes) != OK) {
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if(execi->clearproc) execi->clearproc(execi);
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return ENOMEM;
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}
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#if ELF_DEBUG
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printf("mmapped 0x%lx-0x%lx\n", vaddr, vaddr+seg_membytes);
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#endif
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/* Copy executable section into it */
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if(execi->copymem(execi, ph->p_offset, p_vaddr, ph->p_filesz) != OK) {
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if(execi->clearproc) execi->clearproc(execi);
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return ENOMEM;
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}
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#if ELF_DEBUG
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printf("copied 0x%lx-0x%lx\n", p_vaddr, p_vaddr+ph->p_filesz);
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#endif
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/* Clear remaining bits */
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vmemend = vaddr + seg_membytes;
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if((chunk = p_vaddr - vaddr) > 0) {
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#if ELF_DEBUG
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printf("start clearing 0x%lx-0x%lx\n", vaddr, vaddr+chunk);
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#endif
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execi->clearmem(execi, vaddr, chunk);
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}
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if((chunk = vmemend - vfileend) > 0) {
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#if ELF_DEBUG
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printf("end clearing 0x%lx-0x%lx\n", vfileend, vfileend+chunk);
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#endif
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execi->clearmem(execi, vfileend, chunk);
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}
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}
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}
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/* Make it a stack */
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if(execi->allocmem_ondemand(execi, stacklow, execi->stack_size) != OK) {
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if(execi->clearproc) execi->clearproc(execi);
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return ENOMEM;
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}
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#if ELF_DEBUG
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printf("stack mmapped 0x%lx-0x%lx\n", stacklow, stacklow+execi->stack_size);
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#endif
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/* record entry point and lowest load vaddr for caller */
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execi->pc = hdr->e_entry + execi->load_offset;
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execi->load_base = startv;
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return OK;
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}
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