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Message-Id: <20240612195921.2685842-1-kees@kernel.org>
Date: Wed, 12 Jun 2024 12:59:18 -0700
From: Kees Cook <kees@...nel.org>
To: Mark Rutland <mark.rutland@....com>
Cc: Kees Cook <kees@...nel.org>,
David Gow <davidgow@...gle.com>,
Vitor Massaru Iha <vitor@...saru.org>,
Ivan Orlov <ivan.orlov0322@...il.com>,
Brendan Higgins <brendan.higgins@...ux.dev>,
Rae Moar <rmoar@...gle.com>,
"Gustavo A. R. Silva" <gustavoars@...nel.org>,
linux-kernel@...r.kernel.org,
linux-kselftest@...r.kernel.org,
kunit-dev@...glegroups.com,
linux-hardening@...r.kernel.org
Subject: [PATCH v3 1/2] kunit: test: Add vm_mmap() allocation resource manager
For tests that need to allocate using vm_mmap() (e.g. usercopy and
execve), provide the interface to have the allocation tracked by KUnit
itself. This requires bringing up a placeholder userspace mm.
This combines my earlier attempt at this with Mark Rutland's version[1].
Normally alloc_mm() and arch_pick_mmap_layout() aren't exported for
modules, so export these only for KUnit testing.
Link: https://lore.kernel.org/lkml/20230321122514.1743889-2-mark.rutland@arm.com/ [1]
Co-developed-by: Mark Rutland <mark.rutland@....com>
Signed-off-by: Mark Rutland <mark.rutland@....com>
Reviewed-by: David Gow <davidgow@...gle.com>
Signed-off-by: Kees Cook <kees@...nel.org>
---
include/kunit/test.h | 17 +++++++
kernel/fork.c | 3 ++
lib/kunit/Makefile | 1 +
lib/kunit/user_alloc.c | 113 +++++++++++++++++++++++++++++++++++++++++
mm/util.c | 3 ++
5 files changed, 137 insertions(+)
create mode 100644 lib/kunit/user_alloc.c
diff --git a/include/kunit/test.h b/include/kunit/test.h
index e32b4cb7afa2..ec61cad6b71d 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -480,6 +480,23 @@ static inline void *kunit_kcalloc(struct kunit *test, size_t n, size_t size, gfp
return kunit_kmalloc_array(test, n, size, gfp | __GFP_ZERO);
}
+/**
+ * kunit_vm_mmap() - Allocate KUnit-tracked vm_mmap() area
+ * @test: The test context object.
+ * @file: struct file pointer to map from, if any
+ * @addr: desired address, if any
+ * @len: how many bytes to allocate
+ * @prot: mmap PROT_* bits
+ * @flag: mmap flags
+ * @offset: offset into @file to start mapping from.
+ *
+ * See vm_mmap() for more information.
+ */
+unsigned long kunit_vm_mmap(struct kunit *test, struct file *file,
+ unsigned long addr, unsigned long len,
+ unsigned long prot, unsigned long flag,
+ unsigned long offset);
+
void kunit_cleanup(struct kunit *test);
void __printf(2, 3) kunit_log_append(struct string_stream *log, const char *fmt, ...);
diff --git a/kernel/fork.c b/kernel/fork.c
index 99076dbe27d8..cea203197136 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -115,6 +115,8 @@
#define CREATE_TRACE_POINTS
#include <trace/events/task.h>
+#include <kunit/visibility.h>
+
/*
* Minimum number of threads to boot the kernel
*/
@@ -1334,6 +1336,7 @@ struct mm_struct *mm_alloc(void)
memset(mm, 0, sizeof(*mm));
return mm_init(mm, current, current_user_ns());
}
+EXPORT_SYMBOL_IF_KUNIT(mm_alloc);
static inline void __mmput(struct mm_struct *mm)
{
diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile
index 309659a32a78..56dd67dc6e57 100644
--- a/lib/kunit/Makefile
+++ b/lib/kunit/Makefile
@@ -2,6 +2,7 @@ obj-$(CONFIG_KUNIT) += kunit.o
kunit-objs += test.o \
resource.o \
+ user_alloc.o \
static_stub.o \
string-stream.o \
assert.o \
diff --git a/lib/kunit/user_alloc.c b/lib/kunit/user_alloc.c
new file mode 100644
index 000000000000..76d3d1345ed7
--- /dev/null
+++ b/lib/kunit/user_alloc.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit userspace memory allocation resource management.
+ */
+#include <kunit/resource.h>
+#include <kunit/test.h>
+#include <linux/kthread.h>
+#include <linux/mm.h>
+
+struct kunit_vm_mmap_resource {
+ unsigned long addr;
+ size_t size;
+};
+
+/* vm_mmap() arguments */
+struct kunit_vm_mmap_params {
+ struct file *file;
+ unsigned long addr;
+ unsigned long len;
+ unsigned long prot;
+ unsigned long flag;
+ unsigned long offset;
+};
+
+/* Create and attach a new mm if it doesn't already exist. */
+static int kunit_attach_mm(void)
+{
+ struct mm_struct *mm;
+
+ if (current->mm)
+ return 0;
+
+ mm = mm_alloc();
+ if (!mm)
+ return -ENOMEM;
+
+ /* Define the task size. */
+ mm->task_size = TASK_SIZE;
+
+ /* Make sure we can allocate new VMAs. */
+ arch_pick_mmap_layout(mm, ¤t->signal->rlim[RLIMIT_STACK]);
+
+ /* Attach the mm. It will be cleaned up when the process dies. */
+ kthread_use_mm(mm);
+
+ return 0;
+}
+
+static int kunit_vm_mmap_init(struct kunit_resource *res, void *context)
+{
+ struct kunit_vm_mmap_params *p = context;
+ struct kunit_vm_mmap_resource vres;
+ int ret;
+
+ ret = kunit_attach_mm();
+ if (ret)
+ return ret;
+
+ vres.size = p->len;
+ vres.addr = vm_mmap(p->file, p->addr, p->len, p->prot, p->flag, p->offset);
+ if (!vres.addr)
+ return -ENOMEM;
+ res->data = kmemdup(&vres, sizeof(vres), GFP_KERNEL);
+ if (!res->data) {
+ vm_munmap(vres.addr, vres.size);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static void kunit_vm_mmap_free(struct kunit_resource *res)
+{
+ struct kunit_vm_mmap_resource *vres = res->data;
+
+ /*
+ * Since this is executed from the test monitoring process,
+ * the test's mm has already been torn down. We don't need
+ * to run vm_munmap(vres->addr, vres->size), only clean up
+ * the vres.
+ */
+
+ kfree(vres);
+ res->data = NULL;
+}
+
+unsigned long kunit_vm_mmap(struct kunit *test, struct file *file,
+ unsigned long addr, unsigned long len,
+ unsigned long prot, unsigned long flag,
+ unsigned long offset)
+{
+ struct kunit_vm_mmap_params params = {
+ .file = file,
+ .addr = addr,
+ .len = len,
+ .prot = prot,
+ .flag = flag,
+ .offset = offset,
+ };
+ struct kunit_vm_mmap_resource *vres;
+
+ vres = kunit_alloc_resource(test,
+ kunit_vm_mmap_init,
+ kunit_vm_mmap_free,
+ GFP_KERNEL,
+ ¶ms);
+ if (vres)
+ return vres->addr;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(kunit_vm_mmap);
+
+MODULE_IMPORT_NS(EXPORTED_FOR_KUNIT_TESTING);
diff --git a/mm/util.c b/mm/util.c
index c9e519e6811f..df37c47d9374 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -26,6 +26,8 @@
#include <linux/uaccess.h>
+#include <kunit/visibility.h>
+
#include "internal.h"
#include "swap.h"
@@ -482,6 +484,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
clear_bit(MMF_TOPDOWN, &mm->flags);
}
#endif
+EXPORT_SYMBOL_IF_KUNIT(arch_pick_mmap_layout);
/**
* __account_locked_vm - account locked pages to an mm's locked_vm
--
2.34.1
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