binfmt handler searching issues

From: Arun Sharma (arun.sharma@intel.com)
Date: Mon Jul 28 2003 - 16:11:49 EST


A script such as

#!/bin/foo.bar
...

where /bin/foo.bar is handled by binfmt_misc, is not handled correctly i.e. the interpreter of foo.bar doesn't receive the correct arguments.

The binfmt_misc handler requires that bprm->filename is appropriately filled so that the argv[1] could be correctly passed to the interpreter.

However, binfmt_script, as it exists today doesn't populate bprm->filename correctly.

Another motivation for this patch is the output of ps. Emulators which use binfmt_misc may want to keep the output of ps consistent with native execution. This requires preserving bprm->filename. The attached patch guarantees this even if we have to go through several binfmt handlers (think of finite loops involving binfmt_script and binfmt_misc).

        -Arun


--- linux/fs/exec.c- Thu Mar 13 11:42:51 2003
+++ linux/fs/exec.c Thu Mar 13 11:43:05 2003
@@ -882,6 +882,7 @@
 
         bprm.file = file;
         bprm.filename = filename;
+ bprm.interp = filename;
         bprm.sh_bang = 0;
         bprm.loader = 0;
         bprm.exec = 0;
--- linux/fs/binfmt_script.c- Thu Mar 13 12:09:28 2003
+++ linux/fs/binfmt_script.c Thu Mar 13 12:09:46 2003
@@ -78,6 +78,8 @@
         retval = copy_strings_kernel(1, &i_name, bprm);
         if (retval) return retval;
         bprm->argc++;
+ bprm->interp = interp;
+
         /*
          * OK, now restart the process with the interpreter's dentry.
          */
--- linux/include/linux/binfmts.h- Thu Mar 13 11:40:41 2003
+++ linux/include/linux/binfmts.h Thu Mar 13 11:42:05 2003
@@ -30,7 +30,10 @@
         int e_uid, e_gid;
         kernel_cap_t cap_inheritable, cap_permitted, cap_effective;
         int argc, envc;
- char * filename; /* Name of binary */
+ char * filename; /* Name of binary as seen by procps */
+ char * interp; /* Name of the binary really executed. Most
+ of the time same as filename, but could be
+ different for binfmt_{misc,script} */
         unsigned long loader, exec;
 };

--- linux/fs/binfmt_script.c- Mon Mar 17 08:10:56 2003
+++ linux/fs/binfmt_script.c Mon Mar 17 08:13:07 2003
@@ -67,7 +67,7 @@
          * user environment and arguments are stored.
          */
         remove_arg_zero(bprm);
- retval = copy_strings_kernel(1, &bprm->filename, bprm);
+ retval = copy_strings_kernel(1, &bprm->interp, bprm);
         if (retval < 0) return retval;
         bprm->argc++;
         if (i_arg) {
 
--- linux/fs/binfmt_misc.c.orig Wed Mar 19 15:45:34 2003
+++ linux/fs/binfmt_misc.c Wed Mar 19 15:49:39 2003
@@ -58,7 +58,7 @@
  */
 static Node *check_file(struct linux_binprm *bprm)
 {
- char *p = strrchr(bprm->filename, '.');
+ char *p = strrchr(bprm->interp, '.');
         struct list_head *l;
 
         for (l = entries.next; l != &entries; l = l->next) {
@@ -125,13 +125,13 @@
         if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
                 remove_arg_zero(bprm);
         }
- retval = copy_strings_kernel(1, &bprm->filename, bprm);
+ retval = copy_strings_kernel(1, &bprm->interp, bprm);
         if (retval < 0) goto _ret;
         bprm->argc++;
         retval = copy_strings_kernel(1, &iname_addr, bprm);
         if (retval < 0) goto _ret;
         bprm->argc++;
- bprm->filename = iname; /* for binfmt_script */
+ bprm->interp = iname; /* for binfmt_script */
 
         file = open_exec(iname);
         retval = PTR_ERR(file);

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