@@ -564,6 +564,39 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long addr,
return ret;
}
+static int sgx_encl_page_copy(void *dst, unsigned long src, unsigned long prot)
+{
+ struct vm_area_struct *vma;
+ int ret;
+
+ /* Hold mmap_sem across copy_from_user() to avoid a TOCTOU race. */
+ down_read(¤t->mm->mmap_sem);
+
+ /* Query vma's VM_MAYEXEC as an indirect path_noexec() check. */
+ if (prot & PROT_EXEC) {
+ vma = find_vma(current->mm, src);
+ if (!vma) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ if (!(vma->vm_flags & VM_MAYEXEC)) {
+ ret = -EACCES;
+ goto out;
+ }
+ }
+
+ if (copy_from_user(dst, (void __user *)src, PAGE_SIZE))
+ ret = -EFAULT;
+ else
+ ret = 0;
+
+out:
+ up_read(¤t->mm->mmap_sem);
+
+ return ret;
+}
+
/**
* sgx_ioc_enclave_add_page - handler for %SGX_IOC_ENCLAVE_ADD_PAGE
*
@@ -604,13 +637,12 @@ static long sgx_ioc_enclave_add_page(struct file *filep, void __user *arg)
data = kmap(data_page);
- if (copy_from_user((void *)data, (void __user *)addp.src, PAGE_SIZE)) {
- ret = -EFAULT;
- goto out;
- }
-
prot = addp.flags & (PROT_READ | PROT_WRITE | PROT_EXEC);
+ ret = sgx_encl_page_copy(data, addp.src, prot);
+ if (ret)
+ goto out;
+
ret = sgx_encl_add_page(encl, addp.addr, data, &secinfo, addp.mrmask,
prot);
if (ret)
Do not allow an enclave page to be mapped with PROT_EXEC if the source vma does not have VM_MAYEXEC. This effectively enforces noexec as do_mmap() clears VM_MAYEXEC if the vma is being loaded from a noexec path, i.e. prevents executing a file by loading it into an enclave. Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> --- arch/x86/kernel/cpu/sgx/driver/ioctl.c | 42 +++++++++++++++++++++++--- 1 file changed, 37 insertions(+), 5 deletions(-)