On Sun, May 19, 2024 at 12:12:52PM -0700, Kees Cook wrote: > 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]. > > Link: https://lore.kernel.org/lkml/20230321122514.1743889-2-mark.rutland@xxxxxxx/ [1] > Co-developed-by: Mark Rutland <mark.rutland@xxxxxxx> > Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > --- > include/kunit/test.h | 17 ++++++ > lib/kunit/test.c | 139 ++++++++++++++++++++++++++++++++++++++++++- > 2 files changed, 155 insertions(+), 1 deletion(-) > > diff --git a/include/kunit/test.h b/include/kunit/test.h > index 61637ef32302..8c3835a6f282 100644 > --- a/include/kunit/test.h > +++ b/include/kunit/test.h > @@ -478,6 +478,23 @@ 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/lib/kunit/test.c b/lib/kunit/test.c > index 1d1475578515..09194dbffb63 100644 > --- a/lib/kunit/test.c > +++ b/lib/kunit/test.c > @@ -11,13 +11,14 @@ > #include <kunit/test-bug.h> > #include <kunit/attributes.h> > #include <linux/kernel.h> > +#include <linux/kthread.h> > +#include <linux/mm.h> > #include <linux/module.h> > #include <linux/moduleparam.h> > #include <linux/mutex.h> > #include <linux/panic.h> > #include <linux/sched/debug.h> > #include <linux/sched.h> > -#include <linux/mm.h> > > #include "debugfs.h" > #include "device-impl.h" > @@ -871,6 +872,142 @@ void kunit_kfree(struct kunit *test, const void *ptr) > } > EXPORT_SYMBOL_GPL(kunit_kfree); > > +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; > +}; > + > +/* > + * Arbitrarily chosen user address for the base allocation. > + */ > +#define UBUF_ADDR_BASE SZ_2M > + > +/* Create and attach a new mm if it doesn't already exist. */ > +static int kunit_attach_mm(void) > +{ > + struct vm_area_struct *vma; > + struct mm_struct *mm; > + > + if (current->mm) > + return 0; My tests deliberately created/destroyed the mm for each test; surely we don't want to inherit an MM in some arbitrary state? ... or is this just so the mm can be allocated lazily upon the first mmap() within a test? > + > + mm = mm_alloc(); > + if (!mm) > + return -ENOMEM; > + > + if (mmap_write_lock_killable(mm)) > + goto out_free; > + > + /* Define the task size. */ > + mm->task_size = TASK_SIZE; > + > + /* Prepare the base VMA. */ > + vma = vm_area_alloc(mm); > + if (!vma) > + goto out_unlock; > + > + vma_set_anonymous(vma); > + vma->vm_start = UBUF_ADDR_BASE; > + vma->vm_end = UBUF_ADDR_BASE + PAGE_SIZE; > + vm_flags_init(vma, VM_READ | VM_MAYREAD | VM_WRITE | VM_MAYWRITE); > + vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); > + > + if (insert_vm_struct(mm, vma)) > + goto out_free_vma; > + > + mmap_write_unlock(mm); Why do we need this VMA given you have kunit_vm_mmap()? This existed in my uaccess tests because I didn't use vm_mmap(), and I wanted complete control over the addresses used. Given you add kunit_vm_mmap(), I don't think we want this VMA -- it doesn't serve any real purpose to tests, and accesses can erroneously hit it, which is problematic. UBUF_ADDR_BASE shouldn't be necessary either with kunit_vm_mmap(), unless you want to use fixed addresses. That was just arbitrarily chosen to be above NULL and the usual minimum mmap limit. Mark. > + > + /* 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; > + > +out_free_vma: > + vm_area_free(vma); > +out_unlock: > + mmap_write_unlock(mm); > +out_free: > + mmput(mm); > + return -ENOMEM; > +} > + > +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); > + > void kunit_cleanup(struct kunit *test) > { > struct kunit_resource *res; > -- > 2.34.1 >
