Commit 60bfba7e authored by Jan Kratochvil's avatar Jan Kratochvil Committed by Linus Torvalds
Browse files

PIE randomization 

This patch is using mmap()'s randomization functionality in such a way that
it maps the main executable of (specially compiled/linked -pie/-fpie)
ET_DYN binaries onto a random address (in cases in which mmap() is allowed
to perform a randomization).

Origin of this patch is in exec-shield
(http://people.redhat.com/mingo/exec-shield/

)

[jkosina@suse.cz: pie randomization: fix BAD_ADDR macro]
Signed-off-by: default avatarJan Kratochvil <honza@jikos.cz>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Roland McGrath <roland@redhat.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f057eac0

arch/ia64/ia32/binfmt_elf32.c

+1 −1
Original line number Diff line number Diff line
@@ -261,7 +261,7 @@ elf32_set_personality (void) 
}



static unsigned long

elf32_map (struct file *filep, unsigned long addr, struct elf_phdr *eppnt, int prot, int type)

elf32_map (struct file *filep, unsigned long addr, struct elf_phdr *eppnt, int prot, int type, unsigned long unused)

{

	unsigned long pgoff = (eppnt->p_vaddr) & ~IA32_PAGE_MASK;

fs/binfmt_elf.c

+86 −23
Original line number Diff line number Diff line
@@ -45,7 +45,7 @@ 


static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs);

static int load_elf_library(struct file *);

static unsigned long elf_map (struct file *, unsigned long, struct elf_phdr *, int, int);

static unsigned long elf_map (struct file *, unsigned long, struct elf_phdr *, int, int, unsigned long);



/*

 * If we don't support core dumping, then supply a NULL so we
@@ -80,7 +80,7 @@ static struct linux_binfmt elf_format = { 
		.hasvdso	= 1

};



#define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)

#define BAD_ADDR(x) IS_ERR_VALUE(x)



static int set_brk(unsigned long start, unsigned long end)

{
@@ -285,33 +285,70 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec, 
#ifndef elf_map



static unsigned long elf_map(struct file *filep, unsigned long addr,

		struct elf_phdr *eppnt, int prot, int type)

		struct elf_phdr *eppnt, int prot, int type,

		unsigned long total_size)

{

	unsigned long map_addr;

	unsigned long pageoffset = ELF_PAGEOFFSET(eppnt->p_vaddr);

	unsigned long size = eppnt->p_filesz + ELF_PAGEOFFSET(eppnt->p_vaddr);

	unsigned long off = eppnt->p_offset - ELF_PAGEOFFSET(eppnt->p_vaddr);

	addr = ELF_PAGESTART(addr);

	size = ELF_PAGEALIGN(size);



	down_write(&current->mm->mmap_sem);

	/* mmap() will return -EINVAL if given a zero size, but a

	 * segment with zero filesize is perfectly valid */

	if (eppnt->p_filesz + pageoffset)

		map_addr = do_mmap(filep, ELF_PAGESTART(addr),

				   eppnt->p_filesz + pageoffset, prot, type,

				   eppnt->p_offset - pageoffset);

	else

		map_addr = ELF_PAGESTART(addr);

	if (!size)

		return addr;



	down_write(&current->mm->mmap_sem);

	/*

	* total_size is the size of the ELF (interpreter) image.

	* The _first_ mmap needs to know the full size, otherwise

	* randomization might put this image into an overlapping

	* position with the ELF binary image. (since size < total_size)

	* So we first map the 'big' image - and unmap the remainder at

	* the end. (which unmap is needed for ELF images with holes.)

	*/

	if (total_size) {

		total_size = ELF_PAGEALIGN(total_size);

		map_addr = do_mmap(filep, addr, total_size, prot, type, off);

		if (!BAD_ADDR(map_addr))

			do_munmap(current->mm, map_addr+size, total_size-size);

	} else

		map_addr = do_mmap(filep, addr, size, prot, type, off);



	up_write(&current->mm->mmap_sem);

	return(map_addr);

}



#endif /* !elf_map */



static unsigned long total_mapping_size(struct elf_phdr *cmds, int nr)

{

	int i, first_idx = -1, last_idx = -1;



	for (i = 0; i < nr; i++) {

		if (cmds[i].p_type == PT_LOAD) {

			last_idx = i;

			if (first_idx == -1)

				first_idx = i;

		}

	}

	if (first_idx == -1)

		return 0;



	return cmds[last_idx].p_vaddr + cmds[last_idx].p_memsz -

				ELF_PAGESTART(cmds[first_idx].p_vaddr);

}





/* This is much more generalized than the library routine read function,

   so we keep this separate.  Technically the library read function

   is only provided so that we can read a.out libraries that have

   an ELF header */



static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,

		struct file *interpreter, unsigned long *interp_load_addr)

		struct file *interpreter, unsigned long *interp_map_addr,

		unsigned long no_base)

{

	struct elf_phdr *elf_phdata;

	struct elf_phdr *eppnt;
@@ -319,6 +356,7 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, 
	int load_addr_set = 0;

	unsigned long last_bss = 0, elf_bss = 0;

	unsigned long error = ~0UL;

	unsigned long total_size;

	int retval, i, size;



	/* First of all, some simple consistency checks */
@@ -357,6 +395,12 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, 
		goto out_close;

	}



	total_size = total_mapping_size(elf_phdata, interp_elf_ex->e_phnum);

	if (!total_size) {

		error = -EINVAL;

		goto out_close;

	}



	eppnt = elf_phdata;

	for (i = 0; i < interp_elf_ex->e_phnum; i++, eppnt++) {

		if (eppnt->p_type == PT_LOAD) {
@@ -374,9 +418,14 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, 
			vaddr = eppnt->p_vaddr;

			if (interp_elf_ex->e_type == ET_EXEC || load_addr_set)

				elf_type |= MAP_FIXED;

			else if (no_base && interp_elf_ex->e_type == ET_DYN)

				load_addr = -vaddr;



			map_addr = elf_map(interpreter, load_addr + vaddr,

					   eppnt, elf_prot, elf_type);

					   eppnt, elf_prot, elf_type, total_size);

			total_size = 0;

			if (!*interp_map_addr)

				*interp_map_addr = map_addr;

			error = map_addr;

			if (BAD_ADDR(map_addr))

				goto out_close;
@@ -442,8 +491,7 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, 
			goto out_close;

	}



	*interp_load_addr = load_addr;

	error = ((unsigned long)interp_elf_ex->e_entry) + load_addr;

	error = load_addr;



out_close:

	kfree(elf_phdata);
@@ -540,7 +588,8 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) 
	int elf_exec_fileno;

	int retval, i;

	unsigned int size;

	unsigned long elf_entry, interp_load_addr = 0;

	unsigned long elf_entry;

	unsigned long interp_load_addr = 0;

	unsigned long start_code, end_code, start_data, end_data;

	unsigned long reloc_func_desc = 0;

	char passed_fileno[6];
@@ -808,9 +857,7 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) 
	current->mm->start_stack = bprm->p;



	/* Now we do a little grungy work by mmaping the ELF image into

	   the correct location in memory.  At this point, we assume that

	   the image should be loaded at fixed address, not at a variable

	   address. */

	   the correct location in memory. */

	for(i = 0, elf_ppnt = elf_phdata;

	    i < loc->elf_ex.e_phnum; i++, elf_ppnt++) {

		int elf_prot = 0, elf_flags;
@@ -864,11 +911,15 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) 
			 * default mmap base, as well as whatever program they

			 * might try to exec.  This is because the brk will

			 * follow the loader, and is not movable.  */

#ifdef CONFIG_X86

			load_bias = 0;

#else

			load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr);

#endif

		}



		error = elf_map(bprm->file, load_bias + vaddr, elf_ppnt,

				elf_prot, elf_flags);

				elf_prot, elf_flags,0);

		if (BAD_ADDR(error)) {

			send_sig(SIGKILL, current, 0);

			retval = IS_ERR((void *)error) ?
@@ -944,13 +995,25 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) 
	}



	if (elf_interpreter) {

		if (interpreter_type == INTERPRETER_AOUT)

		if (interpreter_type == INTERPRETER_AOUT) {

			elf_entry = load_aout_interp(&loc->interp_ex,

						     interpreter);

		else

		} else {

			unsigned long interp_map_addr;	/* unused */



			elf_entry = load_elf_interp(&loc->interp_elf_ex,

						    interpreter,

						    &interp_load_addr);

						    &interp_map_addr,

						    load_bias);

			if (!BAD_ADDR(elf_entry)) {

				/*

				 * load_elf_interp() returns relocation

				 * adjustment

				 */

				interp_load_addr = elf_entry;

				elf_entry += loc->interp_elf_ex.e_entry;

			}

		}

		if (BAD_ADDR(elf_entry)) {

			force_sig(SIGSEGV, current);

			retval = IS_ERR((void *)elf_entry) ?

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