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exec: cleanup the CONFIG_MODULES logic

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search_binary_handler() uses "for (try=0; try<2; try++)" to avoid "goto"
but the code looks too complicated and horrible imho.  We still need to
check "try == 0" before request_module() and add the additional "break"
for !CONFIG_MODULES case.

Kill this loop and use a simple "bool need_retry" + "goto retry".  The
code looks much simpler and we do not even need ifdef's, gcc can optimize
out the "if (need_retry)" block if !IS_ENABLED().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Zach Levis <zml@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov
2013-09-11 14:24:44 -07:00
committed by Linus Torvalds
parent 92eaa565ad
commit cb7b6b1cbc
1 changed files with 33 additions and 39 deletions
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72
fs/exec.c
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@@ -1367,13 +1367,15 @@ out:
} }
EXPORT_SYMBOL(remove_arg_zero); EXPORT_SYMBOL(remove_arg_zero);
#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
/* /*
* cycle the list of binary formats handler, until one recognizes the image * cycle the list of binary formats handler, until one recognizes the image
*/ */
int search_binary_handler(struct linux_binprm *bprm) int search_binary_handler(struct linux_binprm *bprm)
{ {
int try, retval; bool need_retry = IS_ENABLED(CONFIG_MODULES);
struct linux_binfmt *fmt; struct linux_binfmt *fmt;
int retval;
/* This allows 4 levels of binfmt rewrites before failing hard. */ /* This allows 4 levels of binfmt rewrites before failing hard. */
if (bprm->recursion_depth > 5) if (bprm->recursion_depth > 5)
@@ -1388,47 +1390,39 @@ int search_binary_handler(struct linux_binprm *bprm)
return retval; return retval;
retval = -ENOENT; retval = -ENOENT;
for (try=0; try<2; try++) { retry:
read_lock(&binfmt_lock); read_lock(&binfmt_lock);
list_for_each_entry(fmt, &formats, lh) { list_for_each_entry(fmt, &formats, lh) {
if (!try_module_get(fmt->module)) if (!try_module_get(fmt->module))
continue; continue;
read_unlock(&binfmt_lock);
bprm->recursion_depth++;
retval = fmt->load_binary(bprm);
bprm->recursion_depth--;
if (retval >= 0) {
put_binfmt(fmt);
return retval;
}
read_lock(&binfmt_lock);
put_binfmt(fmt);
if (retval != -ENOEXEC || bprm->mm == NULL)
break;
if (!bprm->file) {
read_unlock(&binfmt_lock);
return retval;
}
}
read_unlock(&binfmt_lock); read_unlock(&binfmt_lock);
#ifdef CONFIG_MODULES bprm->recursion_depth++;
if (retval != -ENOEXEC || bprm->mm == NULL) { retval = fmt->load_binary(bprm);
break; bprm->recursion_depth--;
} else { if (retval >= 0) {
#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) put_binfmt(fmt);
if (printable(bprm->buf[0]) && return retval;
printable(bprm->buf[1]) && }
printable(bprm->buf[2]) && read_lock(&binfmt_lock);
printable(bprm->buf[3])) put_binfmt(fmt);
break; /* -ENOEXEC */ if (retval != -ENOEXEC || bprm->mm == NULL)
if (try) break;
break; /* -ENOEXEC */ if (!bprm->file) {
request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); read_unlock(&binfmt_lock);
return retval;
} }
#else
break;
#endif
} }
read_unlock(&binfmt_lock);
if (need_retry && retval == -ENOEXEC && bprm->mm) {
if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
printable(bprm->buf[2]) && printable(bprm->buf[3]))
return retval;
request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2));
need_retry = false;
goto retry;
}
return retval; return retval;
} }
EXPORT_SYMBOL(search_binary_handler); EXPORT_SYMBOL(search_binary_handler);