binfmt_elf.c

Linux 1.0 内核C源代码 Linux最早版本代码 由Linus Torvalds亲自书写的

/*
 * linux/fs/binfmt_elf.c
 */
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/a.out.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/binfmts.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/malloc.h>
#include <linux/shm.h>

#include <asm/segment.h>

asmlinkage int sys_exit(int exit_code);
asmlinkage int sys_close(unsigned fd);
asmlinkage int sys_open(const char *, int, int);
asmlinkage int sys_brk(unsigned long);

#define DLINFO_ITEMS 8

#include <linux/elf.h>

/* We need to explicitly zero any fractional pages
   after the data section (i.e. bss).  This would
   contain the junk from the file that should not
   be in memory */

static void padzero(int elf_bss){
  unsigned int fpnt, nbyte;
  
  if(elf_bss & 0xfff) {
    
    nbyte = (PAGE_SIZE - (elf_bss & 0xfff)) & 0xfff;
    if(nbyte){
      verify_area(VERIFY_WRITE, (void *) elf_bss, nbyte);
      
      fpnt = elf_bss;
      while(fpnt & 0xfff) put_fs_byte(0, fpnt++);
    };
  };
}

unsigned long * create_elf_tables(char * p,int argc,int envc,struct elfhdr * exec, unsigned int load_addr, int ibcs)
{
	unsigned long *argv,*envp, *dlinfo;
	unsigned long * sp;
	struct vm_area_struct *mpnt;

	mpnt = (struct vm_area_struct *)kmalloc(sizeof(*mpnt), GFP_KERNEL);
	if (mpnt) {
		mpnt->vm_task = current;
		mpnt->vm_start = PAGE_MASK & (unsigned long) p;
		mpnt->vm_end = TASK_SIZE;
		mpnt->vm_page_prot = PAGE_PRIVATE|PAGE_DIRTY;
		mpnt->vm_share = NULL;
		mpnt->vm_inode = NULL;
		mpnt->vm_offset = 0;
		mpnt->vm_ops = NULL;
		insert_vm_struct(current, mpnt);
		current->stk_vma = mpnt;
	}
	sp = (unsigned long *) (0xfffffffc & (unsigned long) p);
	if(exec) sp -= DLINFO_ITEMS*2;
	dlinfo = sp;
	sp -= envc+1;
	envp = sp;
	sp -= argc+1;
	argv = sp;
	if (!ibcs) {
		put_fs_long((unsigned long)envp,--sp);
		put_fs_long((unsigned long)argv,--sp);
	}

	/* The constant numbers (0-9) that we are writing here are
	   described in the header file sys/auxv.h on at least
	   some versions of SVr4 */
	if(exec) { /* Put this here for an ELF program interpreter */
	  struct elf_phdr * eppnt;
	  eppnt = (struct elf_phdr *) exec->e_phoff;
	  put_fs_long(3,dlinfo++); put_fs_long(load_addr + exec->e_phoff,dlinfo++);
	  put_fs_long(4,dlinfo++); put_fs_long(sizeof(struct elf_phdr),dlinfo++);
	  put_fs_long(5,dlinfo++); put_fs_long(exec->e_phnum,dlinfo++);
	  put_fs_long(9,dlinfo++); put_fs_long((unsigned long) exec->e_entry,dlinfo++);
	  put_fs_long(7,dlinfo++); put_fs_long(SHM_RANGE_START,dlinfo++);
	  put_fs_long(8,dlinfo++); put_fs_long(0,dlinfo++);
	  put_fs_long(6,dlinfo++); put_fs_long(PAGE_SIZE,dlinfo++);
	  put_fs_long(0,dlinfo++); put_fs_long(0,dlinfo++);
	};

	put_fs_long((unsigned long)argc,--sp);
	current->arg_start = (unsigned long) p;
	while (argc-->0) {
		put_fs_long((unsigned long) p,argv++);
		while (get_fs_byte(p++)) /* nothing */ ;
	}
	put_fs_long(0,argv);
	current->arg_end = current->env_start = (unsigned long) p;
	while (envc-->0) {
		put_fs_long((unsigned long) p,envp++);
		while (get_fs_byte(p++)) /* nothing */ ;
	}
	put_fs_long(0,envp);
	current->env_end = (unsigned long) p;
	return sp;
}


/* This is much more generalized than the library routine read function,
   so we keep this separate.  Techincally the library read function
   is only provided so that we can read a.out libraries that have
   an ELF header */

static unsigned int load_elf_interp(struct elfhdr * interp_elf_ex,
			     struct inode * interpreter_inode)
{
        struct file * file;
	struct elf_phdr *elf_phdata  =  NULL;
	struct elf_phdr *eppnt;
	unsigned int len;
	unsigned int load_addr;
	int elf_exec_fileno;
	int elf_bss;
	int old_fs, retval;
	unsigned int last_bss;
	int error;
	int i, k;
	
	elf_bss = 0;
	last_bss = 0;
	error = load_addr = 0;
	
	/* First of all, some simple consistency checks */
	if((interp_elf_ex->e_type != ET_EXEC && 
	    interp_elf_ex->e_type != ET_DYN) || 
	   (interp_elf_ex->e_machine != EM_386 && interp_elf_ex->e_machine != EM_486) ||
	   (!interpreter_inode->i_op || !interpreter_inode->i_op->bmap || 
	    !interpreter_inode->i_op->default_file_ops->mmap)){
		return 0xffffffff;
	};
	
	/* Now read in all of the header information */
	
	if(sizeof(struct elf_phdr) * interp_elf_ex->e_phnum > PAGE_SIZE) 
	    return 0xffffffff;
	
	elf_phdata =  (struct elf_phdr *) 
		kmalloc(sizeof(struct elf_phdr) * interp_elf_ex->e_phnum, GFP_KERNEL);
	if(!elf_phdata) return 0xffffffff;
	
	old_fs = get_fs();
	set_fs(get_ds());
	retval = read_exec(interpreter_inode, interp_elf_ex->e_phoff, (char *) elf_phdata,
			   sizeof(struct elf_phdr) * interp_elf_ex->e_phnum);
	set_fs(old_fs);
	
	elf_exec_fileno = open_inode(interpreter_inode, O_RDONLY);
	if (elf_exec_fileno < 0) return 0xffffffff;
	file = current->filp[elf_exec_fileno];

	eppnt = elf_phdata;
	for(i=0; i<interp_elf_ex->e_phnum; i++, eppnt++)
	  if(eppnt->p_type == PT_LOAD) {
	    error = do_mmap(file, 
			    eppnt->p_vaddr & 0xfffff000,
			    eppnt->p_filesz + (eppnt->p_vaddr & 0xfff),
			    PROT_READ | PROT_WRITE | PROT_EXEC,
			    MAP_PRIVATE | (interp_elf_ex->e_type == ET_EXEC ? MAP_FIXED : 0),
			    eppnt->p_offset & 0xfffff000);
	    
	    if(!load_addr && interp_elf_ex->e_type == ET_DYN)
	      load_addr = error;
	    k = load_addr + eppnt->p_vaddr + eppnt->p_filesz;
	    if(k > elf_bss) elf_bss = k;
	    if(error < 0 && error > -1024) break;  /* Real error */
	    k = load_addr + eppnt->p_memsz + eppnt->p_vaddr;
	    if(k > last_bss) last_bss = k;
	  }
	
	/* Now use mmap to map the library into memory. */

	
	sys_close(elf_exec_fileno);
	if(error < 0 && error > -1024) {
	        kfree(elf_phdata);
		return 0xffffffff;
	}

	padzero(elf_bss);
	len = (elf_bss + 0xfff) & 0xfffff000; /* What we have mapped so far */

	/* Map the last of the bss segment */
	if (last_bss > len)
	  do_mmap(NULL, len, last_bss-len,
		  PROT_READ|PROT_WRITE|PROT_EXEC,
		  MAP_FIXED|MAP_PRIVATE, 0);
	kfree(elf_phdata);

	return ((unsigned int) interp_elf_ex->e_entry) + load_addr;
}

static unsigned int load_aout_interp(struct exec * interp_ex,
			     struct inode * interpreter_inode)
{
  int retval;
  unsigned int elf_entry;
  
  current->brk = interp_ex->a_bss +
    (current->end_data = interp_ex->a_data +
     (current->end_code = interp_ex->a_text));
  elf_entry = interp_ex->a_entry;
  
  
  if (N_MAGIC(*interp_ex) == OMAGIC) {
    do_mmap(NULL, 0, interp_ex->a_text+interp_ex->a_data,
	    PROT_READ|PROT_WRITE|PROT_EXEC,
	    MAP_FIXED|MAP_PRIVATE, 0);
    retval = read_exec(interpreter_inode, 32, (char *) 0, 
		       interp_ex->a_text+interp_ex->a_data);
  } else if (N_MAGIC(*interp_ex) == ZMAGIC || N_MAGIC(*interp_ex) == QMAGIC) {
    do_mmap(NULL, 0, interp_ex->a_text+interp_ex->a_data,
	    PROT_READ|PROT_WRITE|PROT_EXEC,
	    MAP_FIXED|MAP_PRIVATE, 0);
    retval = read_exec(interpreter_inode,
		       N_TXTOFF(*interp_ex) ,
		       (char *) N_TXTADDR(*interp_ex),
		       interp_ex->a_text+interp_ex->a_data);
  } else
    retval = -1;
  
  if(retval >= 0)
    do_mmap(NULL, (interp_ex->a_text + interp_ex->a_data + 0xfff) & 
	    0xfffff000, interp_ex->a_bss,
	    PROT_READ|PROT_WRITE|PROT_EXEC,
	    MAP_FIXED|MAP_PRIVATE, 0);
  if(retval < 0) return 0xffffffff;
  return elf_entry;
}

/*
 * These are the functions used to load ELF style executables and shared
 * libraries.  There is no binary dependent code anywhere else.
 */

#define INTERPRETER_NONE 0
#define INTERPRETER_AOUT 1
#define INTERPRETER_ELF 2

int load_elf_binary(struct linux_binprm * bprm, struct pt_regs * regs)
{
	struct elfhdr elf_ex;
	struct elfhdr interp_elf_ex;
	struct file * file;
  	struct exec interp_ex;
	struct inode *interpreter_inode;
	unsigned int load_addr;
	unsigned int interpreter_type = INTERPRETER_NONE;
	int i;
	int old_fs;
	int error;
	struct elf_phdr * elf_ppnt, *elf_phdata;
	int elf_exec_fileno;
	unsigned int elf_bss, k, elf_brk;
	int retval;
	char * elf_interpreter;
	unsigned int elf_entry;
	int status;
	unsigned int start_code, end_code, end_data;
	unsigned int elf_stack;
	char passed_fileno[6];
	
	status = 0;
	load_addr = 0;
	elf_ex = *((struct elfhdr *) bprm->buf);	  /* exec-header */
	
	if (elf_ex.e_ident[0] != 0x7f ||
	    strncmp(&elf_ex.e_ident[1], "ELF",3) != 0)
		return  -ENOEXEC;
	
	
	/* First of all, some simple consistency checks */
	if(elf_ex.e_type != ET_EXEC || 
	   (elf_ex.e_machine != EM_386 && elf_ex.e_machine != EM_486) ||
	   (!bprm->inode->i_op || !bprm->inode->i_op->default_file_ops ||
	    !bprm->inode->i_op->default_file_ops->mmap)){
		return -ENOEXEC;
	};
	
	/* Now read in all of the header information */
	
	elf_phdata = (struct elf_phdr *) kmalloc(elf_ex.e_phentsize * 
						 elf_ex.e_phnum, GFP_KERNEL);
	
	old_fs = get_fs();
	set_fs(get_ds());
	retval = read_exec(bprm->inode, elf_ex.e_phoff, (char *) elf_phdata,
			   elf_ex.e_phentsize * elf_ex.e_phnum);
	set_fs(old_fs);
	if (retval < 0) {
	        kfree (elf_phdata);
		return retval;
	}
	
	elf_ppnt = elf_phdata;
	
	elf_bss = 0;
	elf_brk = 0;
	
	elf_exec_fileno = open_inode(bprm->inode, O_RDONLY);

	if (elf_exec_fileno < 0) {
	        kfree (elf_phdata);
		return elf_exec_fileno;
	}