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Remove deprecation of a.out ELF interpreters

PATCH In review Andi Kleen 2 participants 5 messages Jan 30, 2008 – Jan 31, 2008

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Andi Kleen

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#0 lore raw

PATCH 1/1 Remove deprecation of a.out ELF interpreters

Andrew has already queued the patch to remove the support for a.out ELF interpreters. So remove the deprecation with it too.

Documentation/feature-removal-schedule.txt +0 -11
Index: linux/Documentation/feature-removal-schedule.txt
===================================================================
@@ -107,17 +107,6 @@ Who:	Eric Biederman <[email protected]
 
 ---------------------------
 
-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 <[email protected]>
-
----------------------------
-
 What:	remove EXPORT_SYMBOL(kernel_thread)
 When:	August 2006
 Files:	arch/*/kernel/*_ksyms.c
#1 lore raw
Quoted 4 lines · On Wed, 30 Jan 2008 09:40:41 +0100 Andi Kleen <[email protected]> wrote:

Andrew has already queued the patch to remove the support for a.out ELF interpreters. So remove the deprecation with it too.

I'm trying to find which patch I might have queued which did this and came up blank. aout-suppress-aout-library-support-if-config_arch_supports_aout.patch is the only relevant one.

You have such a patch in your tree but afaict that will just wreck David's patch.

Confused.

author
#2 lore raw
Quoted 10 lines · Andrew Morton
Quoted 4 lines · On Wed, 30 Jan 2008 09:40:41 +0100 Andi Kleen <[email protected]> wrote:

Andrew has already queued the patch to remove the support for a.out ELF interpreters. So remove the deprecation with it too.

I'm trying to find which patch I might have queued which did this and came up blank.

Sorry I somehow thought you had it queued.

My patch makes parts of David's patch obsolete because he makes the code ifdef, but I remove the code completely. David also does some other cleanups which still make sense.

So I think the correct way is to apply my patch first and then David's and just ignore all the rejects and refresh. The result should be correct.

Basically after that only the core dump changes in David's patch should be left over.

Can you do that or should I resubmit both patches in a merged form? (I can do that too)

-Andi

#3 lore raw
Quoted 18 lines · On Thu, 31 Jan 2008 04:09:19 +0100 Andi Kleen <[email protected]> wrote:
Quoted 10 lines · Andrew Morton
Quoted 4 lines · On Wed, 30 Jan 2008 09:40:41 +0100 Andi Kleen <[email protected]> wrote:

Andrew has already queued the patch to remove the support for a.out ELF interpreters. So remove the deprecation with it too.

I'm trying to find which patch I might have queued which did this and came up blank.

Sorry I somehow thought you had it queued.

My patch makes parts of David's patch obsolete because he makes the code ifdef, but I remove the code completely. David also does some other cleanups which still make sense.

Quoted 9 lines

So I think the correct way is to apply my patch first and then David's and just ignore all the rejects and refresh. The result should be correct.

Basically after that only the core dump changes in David's patch should be left over.

Can you do that or should I resubmit both patches in a merged form? (I can do that too)

Your patch on top of rc8-mm1 would be simplest for me.

I'm at a bit of a loss because I don't appear to have a copy of the patch which we're discussing handy.

author
#4 lore raw
Quoted 1 line

Your patch on top of rc8-mm1 would be simplest for me.

Here you go. I also folded in the update deprecation file patch so you only need this one, nothing else.

-Andi

---

Remove a.out interpreter support in ELF loader

-mm patch for now. To be applied to 2.6.25.

Following the deprecation schedule the a.out ELF interpreter support is removed now with this patch. a.out ELF interpreters were an transition feature for moving a.out systems to ELF, but they're unlikely to be still needed. Pure a.out systems will still work of course. This allows to simplify the hairy ELF loader.

---
 Documentation/feature-removal-schedule.txt |   11 --
 fs/binfmt_elf.c                            |  129 +----------------------------
 2 files changed, 8 insertions(+), 132 deletions(-)
fs/binfmt_elf.c +21 -152
Index: linux-2.6.24-rc8-mm1/fs/binfmt_elf.c
===================================================================
@@ -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 *b
 
 	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 *b
 	/* 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;
-	}
+	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_in
 #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_
  	unsigned long load_addr = 0, load_bias = 0;
 	int load_addr_set = 0;
 	char * elf_interpreter = NULL;
-	unsigned int interpreter_type = INTERPRETER_NONE;
 	unsigned char ibcs2_interpreter = 0;
 	unsigned long error;
 	struct elf_phdr *elf_ppnt, *elf_phdata;
@@ -621,7 +544,6 @@ static int load_elf_binary(struct linux_
 	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;
@@ -798,62 +720,18 @@ static int load_elf_binary(struct linux_
 
 	/* 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, ibcs2_interpreter);
 	}
 
-	/* 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)
@@ -1031,24 +909,19 @@ static int load_elf_binary(struct linux_
 	}
 
 	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,
-						    interpreter,
-						    &interp_map_addr,
-						    load_bias);
-			if (!IS_ERR((void *)elf_entry)) {
-				/*
-				 * load_elf_interp() returns relocation
-				 * adjustment
-				 */
-				interp_load_addr = elf_entry;
-				elf_entry += loc->interp_elf_ex.e_entry;
-			}
+		unsigned long uninitialized_var(interp_map_addr);
+
+		elf_entry = load_elf_interp(&loc->interp_elf_ex,
+					    interpreter,
+					    &interp_map_addr,
+					    load_bias);
+		if (!IS_ERR((void *)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);
@@ -1072,8 +945,7 @@ static int load_elf_binary(struct linux_
 
 	kfree(elf_phdata);
 
-	if (!IS_AOUT_INTERP(interpreter_type))
-		sys_close(elf_exec_fileno);
+	sys_close(elf_exec_fileno);
 
 	set_binfmt(&elf_format);
 
@@ -1088,15 +960,12 @@ static int load_elf_binary(struct linux_
 	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;
Documentation/feature-removal-schedule.txt +0 -11
Index: linux-2.6.24-rc8-mm1/Documentation/feature-removal-schedule.txt
===================================================================
@@ -90,17 +90,6 @@ Who:	Eric Biederman <[email protected]
 
 ---------------------------
 
-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 <[email protected]>
-
----------------------------
-
 What:	remove EXPORT_SYMBOL(kernel_thread)
 When:	August 2006
 Files:	arch/*/kernel/*_ksyms.c