Remove a.out interpreter support in ELF loader (d20894a2) · Commits · 戴 / test

Documentation/feature-removal-schedule.txt

+0 −11

Original line number	Diff line number	Diff line
		@@ -99,17 +99,6 @@ Who: Eric Biederman <ebiederm@xmission.com>

		---------------------------

		What: a.out interpreter support for ELF executables
		When: 2.6.25
		Files: fs/binfmt_elf.c
		Why: Using a.out interpreters for ELF executables was a feature for
		transition from a.out to ELF. But now it is unlikely to be still
		needed anymore and removing it would simplify the hairy ELF
		loader code.
		Who: Andi Kleen <ak@suse.de>

		---------------------------

		What: remove EXPORT_SYMBOL(kernel_thread)
		When: August 2006
		Files: arch//kernel/_ksyms.c

fs/binfmt_elf.c

+21 −152

Original line number	Diff line number	Diff line
		@@ -134,8 +134,7 @@ static int padzero(unsigned long elf_bss)

		static int
		create_elf_tables(struct linux_binprm bprm, struct elfhdr exec,
		int interp_aout, unsigned long load_addr,
		unsigned long interp_load_addr)
		unsigned long load_addr, unsigned long interp_load_addr)
		{
		unsigned long p = bprm->p;
		int argc = bprm->argc;
		@@ -223,12 +222,7 @@ create_elf_tables(struct linux_binprm bprm, struct elfhdr exec,

		sp = STACK_ADD(p, ei_index);

		items = (argc + 1) + (envc + 1);
		if (interp_aout) {
		items += 3; /* a.out interpreters require argv & envp too */
		} else {
		items += 1; /* ELF interpreters only put argc on the stack */
		}
		items = (argc + 1) + (envc + 1) + 1;
		bprm->p = STACK_ROUND(sp, items);

		/* Point sp at the lowest address on the stack */
		@@ -251,16 +245,8 @@ create_elf_tables(struct linux_binprm bprm, struct elfhdr exec,
		/* Now, let's put argc (and argv, envp if appropriate) on the stack */
		if (__put_user(argc, sp++))
		return -EFAULT;
		if (interp_aout) {
		argv = sp + 2;
		envp = argv + argc + 1;
		if (__put_user((elf_addr_t)(unsigned long)argv, sp++) \|\|
		__put_user((elf_addr_t)(unsigned long)envp, sp++))
		return -EFAULT;
		} else {
		argv = sp;
		envp = argv + argc + 1;
		}

		/* Populate argv and envp */
		p = current->mm->arg_end = current->mm->arg_start;
		@@ -513,61 +499,6 @@ out:
		return error;
		}

		#ifdef CONFIG_ARCH_SUPPORTS_AOUT
		static unsigned long load_aout_interp(struct exec *interp_ex,
		struct file *interpreter)
		{
		unsigned long text_data, elf_entry = ~0UL;
		char __user * addr;
		loff_t offset;

		current->mm->end_code = interp_ex->a_text;
		text_data = interp_ex->a_text + interp_ex->a_data;
		current->mm->end_data = text_data;
		current->mm->brk = interp_ex->a_bss + text_data;

		switch (N_MAGIC(*interp_ex)) {
		case OMAGIC:
		offset = 32;
		addr = (char __user *)0;
		break;
		case ZMAGIC:
		case QMAGIC:
		offset = N_TXTOFF(*interp_ex);
		addr = (char __user )N_TXTADDR(interp_ex);
		break;
		default:
		goto out;
		}

		down_write(&current->mm->mmap_sem);
		do_brk(0, text_data);
		up_write(&current->mm->mmap_sem);
		if (!interpreter->f_op \|\| !interpreter->f_op->read)
		goto out;
		if (interpreter->f_op->read(interpreter, addr, text_data, &offset) < 0)
		goto out;
		flush_icache_range((unsigned long)addr,
		(unsigned long)addr + text_data);

		down_write(&current->mm->mmap_sem);
		do_brk(ELF_PAGESTART(text_data + ELF_MIN_ALIGN - 1),
		interp_ex->a_bss);
		up_write(&current->mm->mmap_sem);
		elf_entry = interp_ex->a_entry;

		out:
		return elf_entry;
		}
		#else
		/* dummy extern - the function should never be called if !CONFIG_AOUT_BINFMT */
		static inline unsigned long load_aout_interp(struct exec *interp_ex,
		struct file *interpreter)
		{
		return -ELIBACC;
		}
		#endif

		/*
		* These are the functions used to load ELF style executables and shared
		* libraries. There is no binary dependent code anywhere else.
		@@ -576,13 +507,6 @@ static inline unsigned long load_aout_interp(struct exec *interp_ex,
		#define INTERPRETER_NONE 0
		#define INTERPRETER_ELF 2

		#ifdef CONFIG_ARCH_SUPPORTS_AOUT
		#define INTERPRETER_AOUT 1
		#define IS_AOUT_INTERP(x) ((x) == INTERPRETER_AOUT)
		#else
		#define IS_AOUT_INTERP(x) (0)
		#endif

		#ifndef STACK_RND_MASK
		#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */
		#endif
		@@ -609,7 +533,6 @@ static int load_elf_binary(struct linux_binprm bprm, struct pt_regs regs)
		unsigned long load_addr = 0, load_bias = 0;
		int load_addr_set = 0;
		char * elf_interpreter = NULL;
		unsigned int interpreter_type = INTERPRETER_NONE;
		unsigned long error;
		struct elf_phdr elf_ppnt, elf_phdata;
		unsigned long elf_bss, elf_brk;
		@@ -620,7 +543,6 @@ static int load_elf_binary(struct linux_binprm bprm, struct pt_regs regs)
		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];
		struct files_struct *files;
		int executable_stack = EXSTACK_DEFAULT;
		unsigned long def_flags = 0;
		@@ -789,62 +711,18 @@ static int load_elf_binary(struct linux_binprm bprm, struct pt_regs regs)

		/* Some simple consistency checks for the interpreter */
		if (elf_interpreter) {
		static int warn;
		#ifdef CONFIG_ARCH_SUPPORTS_AOUT
		interpreter_type = INTERPRETER_ELF \| INTERPRETER_AOUT;

		/* Now figure out which format our binary is */
		if ((N_MAGIC(loc->interp_ex) != OMAGIC) &&
		(N_MAGIC(loc->interp_ex) != ZMAGIC) &&
		(N_MAGIC(loc->interp_ex) != QMAGIC))
		interpreter_type = INTERPRETER_ELF;
		#else
		interpreter_type = INTERPRETER_ELF;
		#endif
		if (memcmp(loc->interp_elf_ex.e_ident, ELFMAG, SELFMAG) != 0)
		interpreter_type &= ~INTERPRETER_ELF;

		if (IS_AOUT_INTERP(interpreter_type) && warn < 10) {
		printk(KERN_WARNING "a.out ELF interpreter %s is "
		"deprecated and will not be supported "
		"after Linux 2.6.25\n", elf_interpreter);
		warn++;
		}

		retval = -ELIBBAD;
		if (!interpreter_type)
		/* Not an ELF interpreter */
		if (memcmp(loc->interp_elf_ex.e_ident, ELFMAG, SELFMAG) != 0)
		goto out_free_dentry;

		/* Make sure only one type was selected */
		if ((interpreter_type & INTERPRETER_ELF) &&
		interpreter_type != INTERPRETER_ELF) {
		// FIXME - ratelimit this before re-enabling
		// printk(KERN_WARNING "ELF: Ambiguous type, using ELF\n");
		interpreter_type = INTERPRETER_ELF;
		}
		/* Verify the interpreter has a valid arch */
		if ((interpreter_type == INTERPRETER_ELF) &&
		!elf_check_arch(&loc->interp_elf_ex))
		if (!elf_check_arch(&loc->interp_elf_ex))
		goto out_free_dentry;
		} else {
		/* Executables without an interpreter also need a personality */
		SET_PERSONALITY(loc->elf_ex, 0);
		}

		/* OK, we are done with that, now set up the arg stuff,
		and then start this sucker up */
		if (IS_AOUT_INTERP(interpreter_type) && !bprm->sh_bang) {
		char *passed_p = passed_fileno;
		sprintf(passed_fileno, "%d", elf_exec_fileno);

		if (elf_interpreter) {
		retval = copy_strings_kernel(1, &passed_p, bprm);
		if (retval)
		goto out_free_dentry;
		bprm->argc++;
		}
		}

		/* Flush all traces of the currently running executable */
		retval = flush_old_exec(bprm);
		if (retval)
		@@ -1022,10 +900,6 @@ static int load_elf_binary(struct linux_binprm bprm, struct pt_regs regs)
		}

		if (elf_interpreter) {
		if (IS_AOUT_INTERP(interpreter_type)) {
		elf_entry = load_aout_interp(&loc->interp_ex,
		interpreter);
		} else {
		unsigned long uninitialized_var(interp_map_addr);

		elf_entry = load_elf_interp(&loc->interp_elf_ex,
		@@ -1040,7 +914,6 @@ static int load_elf_binary(struct linux_binprm bprm, struct pt_regs regs)
		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) ?
		@@ -1063,7 +936,6 @@ static int load_elf_binary(struct linux_binprm bprm, struct pt_regs regs)

		kfree(elf_phdata);

		if (!IS_AOUT_INTERP(interpreter_type))
		sys_close(elf_exec_fileno);

		set_binfmt(&elf_format);
		@@ -1079,15 +951,12 @@ static int load_elf_binary(struct linux_binprm bprm, struct pt_regs regs)
		compute_creds(bprm);
		current->flags &= ~PF_FORKNOEXEC;
		retval = create_elf_tables(bprm, &loc->elf_ex,
		IS_AOUT_INTERP(interpreter_type),
		load_addr, interp_load_addr);
		if (retval < 0) {
		send_sig(SIGKILL, current, 0);
		goto out;
		}
		/* N.B. passed_fileno might not be initialized? */
		if (IS_AOUT_INTERP(interpreter_type))
		current->mm->arg_start += strlen(passed_fileno) + 1;
		current->mm->end_code = end_code;
		current->mm->start_code = start_code;
		current->mm->start_data = start_data;

Admin message