[PATCH] exec: remove legacy custom binfmt modules autoloading
From: Nir Lichtman
Date: Sat Nov 16 2024 - 18:13:35 EST
Problem: The search binary handler logic contains legacy code
to handle automatically loading kernel modules of unsupported
binary formats.
This logic is a leftover from a.out-to-ELF transition.
After removal of a.out support, this code has no use anymore.
Solution: Clean up this code from the search binary handler,
also remove the line initialising retval to -ENOENT and instead
just return -ENOEXEC if the flow has reached the end of the func.
Note: Anyone who might find future uses for this legacy code
would be better off using binfmt_misc to trigger whatever
module loading they might need - would be more flexible that way.
Suggested-by: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Nir Lichtman <nir@xxxxxxxxxxxx>
---
Side-note: This patch is a follow-up for
the discussion on "exec: make printable macro more concise".
fs/exec.c | 16 +---------------
1 file changed, 1 insertion(+), 15 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index 6c53920795c2..f3975b0636bd 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1723,13 +1723,11 @@ int remove_arg_zero(struct linux_binprm *bprm)
}
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
*/
static int search_binary_handler(struct linux_binprm *bprm)
{
- bool need_retry = IS_ENABLED(CONFIG_MODULES);
struct linux_binfmt *fmt;
int retval;
@@ -1741,8 +1739,6 @@ static int search_binary_handler(struct linux_binprm *bprm)
if (retval)
return retval;
- retval = -ENOENT;
- retry:
read_lock(&binfmt_lock);
list_for_each_entry(fmt, &formats, lh) {
if (!try_module_get(fmt->module))
@@ -1760,17 +1756,7 @@ static int search_binary_handler(struct linux_binprm *bprm)
}
read_unlock(&binfmt_lock);
- if (need_retry) {
- if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
- printable(bprm->buf[2]) && printable(bprm->buf[3]))
- return retval;
- if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
- return retval;
- need_retry = false;
- goto retry;
- }
-
- return retval;
+ return -ENOEXEC;
}
/* binfmt handlers will call back into begin_new_exec() on success. */
--
2.39.2