[PATCH V3 10/30] x86/sgx: Create utility to validate user provided offset and length

Reinette Chatre
2022-04-04T21:25:27Z

User provided offset and length is validated when parsing the parameters
of the SGX_IOC_ENCLAVE_ADD_PAGES ioctl(). Extract this validation
into a utility that can be used by the SGX2 ioctl()s that will
also provide these values.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
---
No changes since V2

Changes since V1:
- New patch

arch/x86/kernel/cpu/sgx/ioctl.c | 28 ++++++++++++++++++++++------
1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 83df20e3e633..f487549bccba 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -372,6 +372,26 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src,
return ret;
}

+/*
+ * Ensure user provided offset and length values are valid for
+ * an enclave.
+ */
+static int sgx_validate_offset_length(struct sgx_encl *encl,
+ unsigned long offset,
+ unsigned long length)
+{
+ if (!IS_ALIGNED(offset, PAGE_SIZE))
+ return -EINVAL;
+
+ if (!length || length & (PAGE_SIZE - 1))
+ return -EINVAL;
+
+ if (offset + length - PAGE_SIZE >= encl->size)
+ return -EINVAL;
+
+ return 0;
+}
+
/**
* sgx_ioc_enclave_add_pages() - The handler for %SGX_IOC_ENCLAVE_ADD_PAGES
* @encl: an enclave pointer
@@ -425,14 +445,10 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
if (copy_from_user(&add_arg, arg, sizeof(add_arg)))
return -EFAULT;

- if (!IS_ALIGNED(add_arg.offset, PAGE_SIZE) ||
- !IS_ALIGNED(add_arg.src, PAGE_SIZE))
- return -EINVAL;
-
- if (!add_arg.length || add_arg.length & (PAGE_SIZE - 1))
+ if (!IS_ALIGNED(add_arg.src, PAGE_SIZE))
return -EINVAL;

- if (add_arg.offset + add_arg.length - PAGE_SIZE >= encl->size)
+ if (sgx_validate_offset_length(encl, add_arg.offset, add_arg.length))
return -EINVAL;

if (copy_from_user(&secinfo, (void __user *)add_arg.secinfo,
--
2.25.1