[PATCH mm] [1/2] Remove a.out interpreter support in ELF loader

[PATCH mm] [1/2] Remove a.out interpreter support in ELF loader

[Andi Kleen]

-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.

Signed-off-by: Andi Kleen <ak@suse.de>

---
 Documentation/feature-removal-schedule.txt |   11 --
 fs/binfmt_elf.c                            |  129 +----------------------------
 2 files changed, 8 insertions(+), 132 deletions(-)

Index: linux/fs/binfmt_elf.c
===================================================================
--- linux.orig/fs/binfmt_elf.c
+++ linux/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 +499,11 @@ out:
 	return error;
 }
 
-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;
-}
-
 /*
  * 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
-
 #ifndef STACK_RND_MASK
 #define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))	/* 8MB of VA */
 #endif
@@ -594,7 +530,6 @@ 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;
@@ -606,7 +541,6 @@ 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;
@@ -783,39 +717,11 @@ static int load_elf_binary(struct linux_
 
 	/* Some simple consistency checks for the interpreter */
 	if (elf_interpreter) {
-		static int warn;
-		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;
-
-		if (memcmp(loc->interp_elf_ex.e_ident, ELFMAG, SELFMAG) != 0)
-			interpreter_type &= ~INTERPRETER_ELF;
-
-		if (interpreter_type == INTERPRETER_AOUT && 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)
+		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  */
@@ -824,17 +730,6 @@ static int load_elf_binary(struct linux_
 
 	/* OK, we are done with that, now set up the arg stuff,
 	   and then start this sucker up */
-	if ((!bprm->sh_bang) && (interpreter_type == INTERPRETER_AOUT)) {
-		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);
@@ -1013,10 +908,7 @@ static int load_elf_binary(struct linux_
 	}
 
 	if (elf_interpreter) {
-		if (interpreter_type == INTERPRETER_AOUT) {
-			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,
@@ -1054,8 +946,7 @@ static int load_elf_binary(struct linux_
 
 	kfree(elf_phdata);
 
-	if (interpreter_type != INTERPRETER_AOUT)
-		sys_close(elf_exec_fileno);
+	sys_close(elf_exec_fileno);
 
 	set_binfmt(&elf_format);
 
@@ -1070,15 +961,11 @@ static int load_elf_binary(struct linux_
 	compute_creds(bprm);
 	current->flags &= ~PF_FORKNOEXEC;
 	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;
 	current->mm->end_code = end_code;
 	current->mm->start_code = start_code;
 	current->mm->start_data = start_data;
Index: linux/Documentation/feature-removal-schedule.txt
===================================================================
--- linux.orig/Documentation/feature-removal-schedule.txt
+++ linux/Documentation/feature-removal-schedule.txt
@@ -107,17 +107,6 @@ Who:	Eric Biederman <ebiederm@xmission.c
 
 ---------------------------
 
-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

[PATCH mm] [2/2] Remove ibcs2 support in ELF loader too

[Andi Kleen]

ibcs2 support has never been supported on 2.6 kernels as far as I know,
and if it has it must have been an external patch. Anyways, if anybody
applies an external patch they could as well readd the ibcs checking
code to the ELF loader in the same patch. But there is no reason
to keep this code running in all Linux kernels. This will save at least
two strcmps each ELF execution.

No deprecation period because it could not have been used anyways.

Signed-off-by: Andi Kleen <ak@suse.de>

---
 fs/binfmt_elf.c |   15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

Index: linux/fs/binfmt_elf.c
===================================================================
--- linux.orig/fs/binfmt_elf.c
+++ linux/fs/binfmt_elf.c
@@ -530,7 +530,6 @@ 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 char ibcs2_interpreter = 0;
 	unsigned long error;
 	struct elf_phdr *elf_ppnt, *elf_phdata;
 	unsigned long elf_bss, elf_brk;
@@ -647,14 +646,6 @@ static int load_elf_binary(struct linux_
 			if (elf_interpreter[elf_ppnt->p_filesz - 1] != '\0')
 				goto out_free_interp;
 
-			/* If the program interpreter is one of these two,
-			 * then assume an iBCS2 image. Otherwise assume
-			 * a native linux image.
-			 */
-			if (strcmp(elf_interpreter,"/usr/lib/libc.so.1") == 0 ||
-			    strcmp(elf_interpreter,"/usr/lib/ld.so.1") == 0)
-				ibcs2_interpreter = 1;
-
 			/*
 			 * The early SET_PERSONALITY here is so that the lookup
 			 * for the interpreter happens in the namespace of the 
@@ -674,7 +665,7 @@ static int load_elf_binary(struct linux_
 			 * switch really is going to happen - do this in
 			 * flush_thread().	- akpm
 			 */
-			SET_PERSONALITY(loc->elf_ex, ibcs2_interpreter);
+			SET_PERSONALITY(loc->elf_ex, 0);
 
 			interpreter = open_exec(elf_interpreter);
 			retval = PTR_ERR(interpreter);
@@ -725,7 +716,7 @@ static int load_elf_binary(struct linux_
 			goto out_free_dentry;
 	} else {
 		/* Executables without an interpreter also need a personality  */
-		SET_PERSONALITY(loc->elf_ex, ibcs2_interpreter);
+		SET_PERSONALITY(loc->elf_ex, 0);
 	}
 
 	/* OK, we are done with that, now set up the arg stuff,
@@ -748,7 +739,7 @@ static int load_elf_binary(struct linux_
 
 	/* Do this immediately, since STACK_TOP as used in setup_arg_pages
 	   may depend on the personality.  */
-	SET_PERSONALITY(loc->elf_ex, ibcs2_interpreter);
+	SET_PERSONALITY(loc->elf_ex, 0);
 	if (elf_read_implies_exec(loc->elf_ex, executable_stack))
 		current->personality |= READ_IMPLIES_EXEC;