From: Jessica Yu <jeyu@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
keescook@chromium.org, Josh Poimboeuf <jpoimboe@redhat.com>,
Miroslav Benes <mbenes@suse.cz>, Jessica Yu <jeyu@kernel.org>
Subject: [PATCH] module: break nested ARCH_HAS_STRICT_MODULE_RWX and STRICT_MODULE_RWX #ifdefs
Date: Wed, 8 Apr 2020 17:43:23 +0200 [thread overview]
Message-ID: <20200408154323.20631-1-jeyu@kernel.org> (raw)
In-Reply-To: <20200408153249.GA26619@linux-8ccs>
Various frob_* and module_{enable,disable}_* functions are defined in a
CONFIG_ARCH_HAS_STRICT_MODULE_RWX ifdef block which also has a nested
CONFIG_STRICT_MODULE_RWX ifdef block within it. This is unecessary and
makes things hard to read. Not only that, this construction requires
redundant empty stubs for module_enable_nx(). I suspect this was
originally done for cosmetic reasons - to keep all the frob_* functions
in the same place, and all the module_{enable,disable}_* functions right
after, but as a result it made the code harder to read.
Make this more readable by unnesting the ifdef blocks and getting rid of
the redundant empty stubs.
Signed-off-by: Jessica Yu <jeyu@kernel.org>
---
kernel/module.c | 29 ++++++++++++++++++-----------
1 file changed, 18 insertions(+), 11 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c
index b88ec9cd2a7f..2b28f8bf2322 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1943,7 +1943,6 @@ static void mod_sysfs_teardown(struct module *mod)
mod_sysfs_fini(mod);
}
-#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
/*
* LKM RO/NX protection: protect module's text/ro-data
* from modification and any data from execution.
@@ -1957,6 +1956,14 @@ static void mod_sysfs_teardown(struct module *mod)
*
* These values are always page-aligned (as is base)
*/
+
+/*
+ * Since some arches are moving towards PAGE_KERNEL module allocations instead
+ * of PAGE_KERNEL_EXEC, keep frob_text() and module_enable_x() outside of the
+ * CONFIG_STRICT_MODULE_RWX block below because they are needed regardless of
+ * whether we are strict.
+ */
+#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
static void frob_text(const struct module_layout *layout,
int (*set_memory)(unsigned long start, int num_pages))
{
@@ -1966,6 +1973,15 @@ static void frob_text(const struct module_layout *layout,
layout->text_size >> PAGE_SHIFT);
}
+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_x(const struct module *mod) { }
+#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
+
#ifdef CONFIG_STRICT_MODULE_RWX
static void frob_rodata(const struct module_layout *layout,
int (*set_memory)(unsigned long start, int num_pages))
@@ -2037,18 +2053,9 @@ static void module_enable_nx(const struct module *mod)
}
#else /* !CONFIG_STRICT_MODULE_RWX */
+/* module_{enable,disable}_ro() stubs are in module.h */
static void module_enable_nx(const struct module *mod) { }
#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
/*
--
2.16.4
next prev parent reply other threads:[~2020-04-08 15:44 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-03 17:13 [PATCH v2] module: Harden STRICT_MODULE_RWX Peter Zijlstra
2020-04-03 20:31 ` Kees Cook
2020-04-08 15:32 ` Jessica Yu
2020-04-08 15:43 ` Jessica Yu [this message]
2020-04-08 15:57 ` Peter Zijlstra
2020-04-08 16:20 ` Jessica Yu
2020-08-08 8:12 ` Mauro Carvalho Chehab
2020-08-10 9:25 ` Jessica Yu
2020-08-10 15:06 ` Jessica Yu
2020-08-11 14:34 ` Mauro Carvalho Chehab
2020-08-11 14:55 ` peterz
2020-08-11 15:27 ` Mauro Carvalho Chehab
2020-08-11 16:01 ` Jessica Yu
2020-08-11 16:57 ` Will Deacon
2020-08-11 17:59 ` peterz
2020-08-11 21:29 ` Peter Zijlstra
2020-08-12 8:56 ` Ard Biesheuvel
2020-08-12 10:40 ` peterz
2020-08-12 11:41 ` Jessica Yu
2020-08-12 13:14 ` H.J. Lu
2020-08-12 12:56 ` Will Deacon
2020-08-12 14:15 ` Szabolcs Nagy
2020-08-12 16:00 ` Jessica Yu
2020-08-12 16:37 ` Ard Biesheuvel
2020-08-12 16:42 ` Szabolcs Nagy
2020-08-13 9:00 ` Will Deacon
2020-08-12 20:00 ` Peter Zijlstra
2020-08-13 8:36 ` Ard Biesheuvel
2020-08-13 13:04 ` Jessica Yu
2020-08-13 13:07 ` Ard Biesheuvel
2020-08-21 12:20 ` Will Deacon
2020-08-21 12:27 ` Ard Biesheuvel
2020-08-21 12:30 ` Will Deacon
2020-08-22 13:47 ` Ard Biesheuvel
2020-08-24 15:24 ` Jessica Yu
2020-08-25 1:54 ` Masahiro Yamada
2020-08-31 9:46 ` Jessica Yu
2020-08-31 10:42 ` Masahiro Yamada
2020-08-31 13:25 ` Ard Biesheuvel
2020-08-31 15:31 ` Jessica Yu
2020-08-31 15:46 ` Masahiro Yamada
2020-09-03 12:37 ` Jessica Yu
2020-09-01 12:51 ` Will Deacon
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