On 2019/6/26 3:21, Jessica Yu wrote:
+++ Yang Yingliang [25/06/19 17:40 +0800]:
If CONFIG_ARCH_HAS_STRICT_MODULE_RWX is not defined,
we need stub for module_enable_nx() and module_enable_x().
If CONFIG_ARCH_HAS_STRICT_MODULE_RWX is defined, but
CONFIG_STRICT_MODULE_RWX is disabled, we need stub for
module_enable_nx.
Move frob_text() outside of the CONFIG_STRICT_MODULE_RWX,
because it is needed anyway.
Maybe include a fixes tag?
Fixes: 2eef1399a866 ("modules: fix BUG when load module with rodata=n")
OK, I will add it in v2.
Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
---
kernel/module.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c
index c3ae34c..cfff441 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1875,7 +1875,7 @@ static void mod_sysfs_teardown(struct module *mod)
mod_sysfs_fini(mod);
}
-#ifdef CONFIG_STRICT_MODULE_RWX
+#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
Could you please explain why you introduced a new
CONFIG_ARCH_HAS_STRICT_MODULE_RWX #ifdef block instead of just moving
frob_text() and module_enable_x() outside of CONFIG_STRICT_MODULE_RWX?
If CONFIG_STRICT_MODULE_RWX is not defined, it has two reasons, one is
that the
arch don't have strict module rwx and the other reason is that
CONFIG_STRICT_MODULE_RWX
is disabled. So I introduce CONFIG_ARCH_HAS_STRICT_MODULE_RWX #ifdef
block to
distinguish this two cases.
I do not have anything against it, although the nested #ifdef's are a
bit painful to read. But I could not find a better way to do it :/
It's awkward because we need module_enable_x() and frob_text()
regardless of of CONFIG_STRICT_MODULE_RWX for x86, but other arches
don't need to call module_enable_x(), they usually just call the empty
stub.
Yes, you are right.
Actually, I was thinking moving all frob_* outside of
CONFIG_STRICT_MODULE_RWX,
because they all should be regardless of of CONFIG_STRICT_MODULE_RWX.
But current
only frob_next() is used, move other frob_* outside of
CONFIG_STRICT_MODULE_RWX
will cause a compile warning if CONFIG_STRICT_MODULE_RWX is disabled, so
I left them
in CONFIG_STRICT_MODULE_RWX. We can move them outside of
CONFIG_STRICT_MODULE_RWX
if they are used in future.
But I think having the CONFIG_ARCH_HAS_STRICT_MODULE_RWX block is OK,
for the reason of limiting the scope of the calls rather than
blanketly calling frob_text() andd module_enable_x() for arches that
don't need to call them. Was that your reasoning as well?
Yes, it's my reasoning.
Thanks,
Yang
Thanks,
Jessica
/*
* LKM RO/NX protection: protect module's text/ro-data
* from modification and any data from execution.
@@ -1898,6 +1898,7 @@ static void frob_text(const struct
module_layout *layout,
layout->text_size >> PAGE_SHIFT);
}
+#ifdef CONFIG_STRICT_MODULE_RWX
static void frob_rodata(const struct module_layout *layout,
int (*set_memory)(unsigned long start, int num_pages))
{
@@ -2010,15 +2011,19 @@ void set_all_modules_text_ro(void)
}
mutex_unlock(&module_mutex);
}
-#else
+#else /* !CONFIG_STRICT_MODULE_RWX */
static void module_enable_nx(const struct module *mod) { }
-#endif
-
+#endif /* CONFIG_STRICT_MODULE_RWX */
static void module_enable_x(const struct module *mod)
{
frob_text(&mod->core_layout, set_memory_x);
frob_text(&mod->init_layout, set_memory_x);
}
+#else /* !CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
+static void module_enable_nx(const struct module *mod) { }
+static void module_enable_x(const struct module *mod) { }
+#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
+
#ifdef CONFIG_LIVEPATCH
/*
--
1.8.3
.
