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Commit b6a2fea3 authored by Ollie Wild's avatar Ollie Wild Committed by Linus Torvalds
Browse files

mm: variable length argument support 



Remove the arg+env limit of MAX_ARG_PAGES by copying the strings directly from
the old mm into the new mm.

We create the new mm before the binfmt code runs, and place the new stack at
the very top of the address space.  Once the binfmt code runs and figures out
where the stack should be, we move it downwards.

It is a bit peculiar in that we have one task with two mm's, one of which is
inactive.

[a.p.zijlstra@chello.nl: limit stack size]
Signed-off-by: default avatarOllie Wild <aaw@google.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <linux-arch@vger.kernel.org>
Cc: Hugh Dickins <hugh@veritas.com>
[bunk@stusta.de: unexport bprm_mm_init]
Signed-off-by: default avatarAdrian Bunk <bunk@stusta.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bdf4c48a

arch/ia64/ia32/binfmt_elf32.c

+16 −51
Original line number Diff line number Diff line
@@ -195,62 +195,27 @@ ia64_elf32_init (struct pt_regs *regs) 
	ia32_load_state(current);

}



/*

 * Undo the override of setup_arg_pages() without this ia32_setup_arg_pages()

 * will suffer infinite self recursion.

 */

#undef setup_arg_pages



int

ia32_setup_arg_pages (struct linux_binprm *bprm, int executable_stack)

{

	unsigned long stack_base;

	struct vm_area_struct *mpnt;

	struct mm_struct *mm = current->mm;

	int i, ret;



	stack_base = IA32_STACK_TOP - MAX_ARG_PAGES*PAGE_SIZE;

	mm->arg_start = bprm->p + stack_base;



	bprm->p += stack_base;

	if (bprm->loader)

		bprm->loader += stack_base;

	bprm->exec += stack_base;



	mpnt = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);

	if (!mpnt)

		return -ENOMEM;



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

	{

		mpnt->vm_mm = current->mm;

		mpnt->vm_start = PAGE_MASK & (unsigned long) bprm->p;

		mpnt->vm_end = IA32_STACK_TOP;

		if (executable_stack == EXSTACK_ENABLE_X)

			mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;

		else if (executable_stack == EXSTACK_DISABLE_X)

			mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;

		else

			mpnt->vm_flags = VM_STACK_FLAGS;

		mpnt->vm_page_prot = (mpnt->vm_flags & VM_EXEC)?

					PAGE_COPY_EXEC: PAGE_COPY;

		if ((ret = insert_vm_struct(current->mm, mpnt))) {

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

			kmem_cache_free(vm_area_cachep, mpnt);

			return ret;

		}

		current->mm->stack_vm = current->mm->total_vm = vma_pages(mpnt);

	}



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

		struct page *page = bprm->page[i];

		if (page) {

			bprm->page[i] = NULL;

			install_arg_page(mpnt, page, stack_base);

		}

		stack_base += PAGE_SIZE;

	}

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

	int ret;



	/* Can't do it in ia64_elf32_init(). Needs to be done before calls to

	   elf32_map() */

	ret = setup_arg_pages(bprm, IA32_STACK_TOP, executable_stack);

	if (!ret) {

		/*

		 * Can't do it in ia64_elf32_init(). Needs to be done before

		 * calls to elf32_map()

		 */

		current->thread.ppl = ia32_init_pp_list();

	}



	return 0;

	return ret;

}



static void

arch/x86_64/ia32/ia32_aout.c

+1 −1
Original line number Diff line number Diff line
@@ -404,7 +404,7 @@ beyond_if: 


	set_brk(current->mm->start_brk, current->mm->brk);



	retval = ia32_setup_arg_pages(bprm, IA32_STACK_TOP, EXSTACK_DEFAULT);

	retval = setup_arg_pages(bprm, IA32_STACK_TOP, EXSTACK_DEFAULT);

	if (retval < 0) { 

		/* Someone check-me: is this error path enough? */ 

		send_sig(SIGKILL, current, 0);

arch/x86_64/ia32/ia32_binfmt.c

+0 −58
Original line number Diff line number Diff line
@@ -232,9 +232,6 @@ do { \ 
#define load_elf_binary load_elf32_binary



#define ELF_PLAT_INIT(r, load_addr)	elf32_init(r)

#define setup_arg_pages(bprm, stack_top, exec_stack) \

	ia32_setup_arg_pages(bprm, stack_top, exec_stack)

int ia32_setup_arg_pages(struct linux_binprm *bprm, unsigned long stack_top, int executable_stack);



#undef start_thread

#define start_thread(regs,new_rip,new_rsp) do { \
@@ -286,61 +283,6 @@ static void elf32_init(struct pt_regs *regs) 
	me->thread.es = __USER_DS;

}



int ia32_setup_arg_pages(struct linux_binprm *bprm, unsigned long stack_top,

			 int executable_stack)

{

	unsigned long stack_base;

	struct vm_area_struct *mpnt;

	struct mm_struct *mm = current->mm;

	int i, ret;



	stack_base = stack_top - MAX_ARG_PAGES * PAGE_SIZE;

	mm->arg_start = bprm->p + stack_base;



	bprm->p += stack_base;

	if (bprm->loader)

		bprm->loader += stack_base;

	bprm->exec += stack_base;



	mpnt = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);

	if (!mpnt) 

		return -ENOMEM; 



	down_write(&mm->mmap_sem);

	{

		mpnt->vm_mm = mm;

		mpnt->vm_start = PAGE_MASK & (unsigned long) bprm->p;

		mpnt->vm_end = stack_top;

		if (executable_stack == EXSTACK_ENABLE_X)

			mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;

		else if (executable_stack == EXSTACK_DISABLE_X)

			mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;

		else

			mpnt->vm_flags = VM_STACK_FLAGS;

 		mpnt->vm_page_prot = (mpnt->vm_flags & VM_EXEC) ? 

 			PAGE_COPY_EXEC : PAGE_COPY;

		if ((ret = insert_vm_struct(mm, mpnt))) {

			up_write(&mm->mmap_sem);

			kmem_cache_free(vm_area_cachep, mpnt);

			return ret;

		}

		mm->stack_vm = mm->total_vm = vma_pages(mpnt);

	} 



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

		struct page *page = bprm->page[i];

		if (page) {

			bprm->page[i] = NULL;

			install_arg_page(mpnt, page, stack_base);

		}

		stack_base += PAGE_SIZE;

	}

	up_write(&mm->mmap_sem);

	

	return 0;

}

EXPORT_SYMBOL(ia32_setup_arg_pages);



#ifdef CONFIG_SYSCTL

/* Register vsyscall32 into the ABI table */

#include <linux/sysctl.h>

fs/binfmt_elf.c

+19 −9
Original line number Diff line number Diff line
@@ -148,6 +148,7 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec, 
	elf_addr_t *elf_info;

	int ei_index = 0;

	struct task_struct *tsk = current;

	struct vm_area_struct *vma;



	/*

	 * If this architecture has a platform capability string, copy it
@@ -234,6 +235,15 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec, 
	sp = (elf_addr_t __user *)bprm->p;

#endif





	/*

	 * Grow the stack manually; some architectures have a limit on how

	 * far ahead a user-space access may be in order to grow the stack.

	 */

	vma = find_extend_vma(current->mm, bprm->p);

	if (!vma)

		return -EFAULT;



	/* Now, let's put argc (and argv, envp if appropriate) on the stack */

	if (__put_user(argc, sp++))

		return -EFAULT;
@@ -254,8 +264,8 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec, 
		size_t len;

		if (__put_user((elf_addr_t)p, argv++))

			return -EFAULT;

		len = strnlen_user((void __user *)p, PAGE_SIZE*MAX_ARG_PAGES);

		if (!len || len > PAGE_SIZE*MAX_ARG_PAGES)

		len = strnlen_user((void __user *)p, MAX_ARG_STRLEN);

		if (!len || len > MAX_ARG_STRLEN)

			return 0;

		p += len;

	}
@@ -266,8 +276,8 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec, 
		size_t len;

		if (__put_user((elf_addr_t)p, envp++))

			return -EFAULT;

		len = strnlen_user((void __user *)p, PAGE_SIZE*MAX_ARG_PAGES);

		if (!len || len > PAGE_SIZE*MAX_ARG_PAGES)

		len = strnlen_user((void __user *)p, MAX_ARG_STRLEN);

		if (!len || len > MAX_ARG_STRLEN)

			return 0;

		p += len;

	}
@@ -826,10 +836,6 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) 
	}



	/* OK, This is the point of no return */

	current->mm->start_data = 0;

	current->mm->end_data = 0;

	current->mm->end_code = 0;

	current->mm->mmap = NULL;

	current->flags &= ~PF_FORKNOEXEC;

	current->mm->def_flags = def_flags;
@@ -1051,9 +1057,13 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) 


	compute_creds(bprm);

	current->flags &= ~PF_FORKNOEXEC;

	create_elf_tables(bprm, &loc->elf_ex,

	retval = create_elf_tables(bprm, &loc->elf_ex,

			  (interpreter_type == INTERPRETER_AOUT),

			  load_addr, interp_load_addr);

	if (retval < 0) {

		send_sig(SIGKILL, current, 0);

		goto out;

	}

	/* N.B. passed_fileno might not be initialized? */

	if (interpreter_type == INTERPRETER_AOUT)

		current->mm->arg_start += strlen(passed_fileno) + 1;

fs/binfmt_elf_fdpic.c

+4 −4
Original line number Diff line number Diff line
@@ -621,8 +621,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm, 
	p = (char __user *) current->mm->arg_start;

	for (loop = bprm->argc; loop > 0; loop--) {

		__put_user((elf_caddr_t) p, argv++);

		len = strnlen_user(p, PAGE_SIZE * MAX_ARG_PAGES);

		if (!len || len > PAGE_SIZE * MAX_ARG_PAGES)

		len = strnlen_user(p, MAX_ARG_STRLEN);

		if (!len || len > MAX_ARG_STRLEN)

			return -EINVAL;

		p += len;

	}
@@ -633,8 +633,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm, 
	current->mm->env_start = (unsigned long) p;

	for (loop = bprm->envc; loop > 0; loop--) {

		__put_user((elf_caddr_t)(unsigned long) p, envp++);

		len = strnlen_user(p, PAGE_SIZE * MAX_ARG_PAGES);

		if (!len || len > PAGE_SIZE * MAX_ARG_PAGES)

		len = strnlen_user(p, MAX_ARG_STRLEN);

		if (!len || len > MAX_ARG_STRLEN)

			return -EINVAL;

		p += len;

	}