Received-SPF: pass (google.com: domain of linux-kernel+bounces-75392-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Date: Wed, 21 Feb 2024 11:40:26 -0800
In-Reply-To: <20240221194052.927623-1-surenb@google.com>
Precedence: bulk
Mime-Version: 1.0
References: <20240221194052.927623-1-surenb@google.com>
Message-ID: <20240221194052.927623-14-surenb@google.com>
Subject: [PATCH v4 13/36] lib: prevent module unloading if memory is not freed
From: Suren Baghdasaryan <surenb@google.com>
To: akpm@linux-foundation.org
Cc: kent.overstreet@linux.dev, mhocko@suse.com, vbabka@suse.cz, 
	hannes@cmpxchg.org, roman.gushchin@linux.dev, mgorman@suse.de, 
	dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, 
	penguin-kernel@i-love.sakura.ne.jp, corbet@lwn.net, void@manifault.com, 
	peterz@infradead.org, juri.lelli@redhat.com, catalin.marinas@arm.com, 
	will@kernel.org, arnd@arndb.de, tglx@linutronix.de, mingo@redhat.com, 
	dave.hansen@linux.intel.com, x86@kernel.org, peterx@redhat.com, 
	david@redhat.com, axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org, 
	nathan@kernel.org, dennis@kernel.org, tj@kernel.org, muchun.song@linux.dev, 
	rppt@kernel.org, paulmck@kernel.org, pasha.tatashin@soleen.com, 
	yosryahmed@google.com, yuzhao@google.com, dhowells@redhat.com, 
	hughd@google.com, andreyknvl@gmail.com, keescook@chromium.org, 
	ndesaulniers@google.com, vvvvvv@google.com, gregkh@linuxfoundation.org, 
	ebiggers@google.com, ytcoode@gmail.com, vincent.guittot@linaro.org, 
	dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, 
	bristot@redhat.com, vschneid@redhat.com, cl@linux.com, penberg@kernel.org, 
	iamjoonsoo.kim@lge.com, 42.hyeyoo@gmail.com, glider@google.com, 
	elver@google.com, dvyukov@google.com, shakeelb@google.com, 
	songmuchun@bytedance.com, jbaron@akamai.com, rientjes@google.com, 
	minchan@google.com, kaleshsingh@google.com, surenb@google.com, 
	kernel-team@android.com, linux-doc@vger.kernel.org, 
	linux-kernel@vger.kernel.org, iommu@lists.linux.dev, 
	linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, 
	linux-modules@vger.kernel.org, kasan-dev@googlegroups.com, 
	cgroups@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"

Skip freeing module's data section if there are non-zero allocation tags
because otherwise, once these allocations are freed, the access to their
code tag would cause UAF.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 include/linux/codetag.h |  6 +++---
 kernel/module/main.c    | 23 +++++++++++++++--------
 lib/codetag.c           | 11 ++++++++---
 3 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/include/linux/codetag.h b/include/linux/codetag.h
index c44f5b83f24d..bfd0ba5c4185 100644
--- a/include/linux/codetag.h
+++ b/include/linux/codetag.h
@@ -35,7 +35,7 @@ struct codetag_type_desc {
 	size_t tag_size;
 	void (*module_load)(struct codetag_type *cttype,
 			    struct codetag_module *cmod);
-	void (*module_unload)(struct codetag_type *cttype,
+	bool (*module_unload)(struct codetag_type *cttype,
 			      struct codetag_module *cmod);
 };
 
@@ -71,10 +71,10 @@ codetag_register_type(const struct codetag_type_desc *desc);
 
 #if defined(CONFIG_CODE_TAGGING) && defined(CONFIG_MODULES)
 void codetag_load_module(struct module *mod);
-void codetag_unload_module(struct module *mod);
+bool codetag_unload_module(struct module *mod);
 #else
 static inline void codetag_load_module(struct module *mod) {}
-static inline void codetag_unload_module(struct module *mod) {}
+static inline bool codetag_unload_module(struct module *mod) { return true; }
 #endif
 
 #endif /* _LINUX_CODETAG_H */
diff --git a/kernel/module/main.c b/kernel/module/main.c
index f400ba076cc7..658b631e76ad 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -1211,15 +1211,19 @@ static void *module_memory_alloc(unsigned int size, enum mod_mem_type type)
 	return module_alloc(size);
 }
 
-static void module_memory_free(void *ptr, enum mod_mem_type type)
+static void module_memory_free(void *ptr, enum mod_mem_type type,
+			       bool unload_codetags)
 {
+	if (!unload_codetags && mod_mem_type_is_core_data(type))
+		return;
+
 	if (mod_mem_use_vmalloc(type))
 		vfree(ptr);
 	else
 		module_memfree(ptr);
 }
 
-static void free_mod_mem(struct module *mod)
+static void free_mod_mem(struct module *mod, bool unload_codetags)
 {
 	for_each_mod_mem_type(type) {
 		struct module_memory *mod_mem = &mod->mem[type];
@@ -1230,20 +1234,23 @@ static void free_mod_mem(struct module *mod)
 		/* Free lock-classes; relies on the preceding sync_rcu(). */
 		lockdep_free_key_range(mod_mem->base, mod_mem->size);
 		if (mod_mem->size)
-			module_memory_free(mod_mem->base, type);
+			module_memory_free(mod_mem->base, type,
+					   unload_codetags);
 	}
 
 	/* MOD_DATA hosts mod, so free it at last */
 	lockdep_free_key_range(mod->mem[MOD_DATA].base, mod->mem[MOD_DATA].size);
-	module_memory_free(mod->mem[MOD_DATA].base, MOD_DATA);
+	module_memory_free(mod->mem[MOD_DATA].base, MOD_DATA, unload_codetags);
 }
 
 /* Free a module, remove from lists, etc. */
 static void free_module(struct module *mod)
 {
+	bool unload_codetags;
+
 	trace_module_free(mod);
 
-	codetag_unload_module(mod);
+	unload_codetags = codetag_unload_module(mod);
 	mod_sysfs_teardown(mod);
 
 	/*
@@ -1285,7 +1292,7 @@ static void free_module(struct module *mod)
 	kfree(mod->args);
 	percpu_modfree(mod);
 
-	free_mod_mem(mod);
+	free_mod_mem(mod, unload_codetags);
 }
 
 void *__symbol_get(const char *symbol)
@@ -2298,7 +2305,7 @@ static int move_module(struct module *mod, struct load_info *info)
 	return 0;
 out_enomem:
 	for (t--; t >= 0; t--)
-		module_memory_free(mod->mem[t].base, t);
+		module_memory_free(mod->mem[t].base, t, true);
 	return ret;
 }
 
@@ -2428,7 +2435,7 @@ static void module_deallocate(struct module *mod, struct load_info *info)
 	percpu_modfree(mod);
 	module_arch_freeing_init(mod);
 
-	free_mod_mem(mod);
+	free_mod_mem(mod, true);
 }
 
 int __weak module_finalize(const Elf_Ehdr *hdr,
diff --git a/lib/codetag.c b/lib/codetag.c
index 9af22648dbfa..b13412ca57cc 100644
--- a/lib/codetag.c
+++ b/lib/codetag.c
@@ -5,6 +5,7 @@
 #include <linux/module.h>
 #include <linux/seq_buf.h>
 #include <linux/slab.h>
+#include <linux/vmalloc.h>
 
 struct codetag_type {
 	struct list_head link;
@@ -239,12 +240,13 @@ void codetag_load_module(struct module *mod)
 	mutex_unlock(&codetag_lock);
 }
 
-void codetag_unload_module(struct module *mod)
+bool codetag_unload_module(struct module *mod)
 {
 	struct codetag_type *cttype;
+	bool unload_ok = true;
 
 	if (!mod)
-		return;
+		return true;
 
 	mutex_lock(&codetag_lock);
 	list_for_each_entry(cttype, &codetag_types, link) {
@@ -261,7 +263,8 @@ void codetag_unload_module(struct module *mod)
 		}
 		if (found) {
 			if (cttype->desc.module_unload)
-				cttype->desc.module_unload(cttype, cmod);
+				if (!cttype->desc.module_unload(cttype, cmod))
+					unload_ok = false;
 
 			cttype->count -= range_size(cttype, &cmod->range);
 			idr_remove(&cttype->mod_idr, mod_id);
@@ -270,4 +273,6 @@ void codetag_unload_module(struct module *mod)
 		up_write(&cttype->mod_lock);
 	}
 	mutex_unlock(&codetag_lock);
+
+	return unload_ok;
 }
-- 
2.44.0.rc0.258.g7320e95886-goog