Linux-Sgx Archive on lore.kernel.org
 help / color / Atom feed
From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: linux-sgx@vger.kernel.org
Subject: [PATCH for_v23 3/4] x86/sgx: Fix EEXTEND error handling
Date: Thu, 10 Oct 2019 15:55:29 -0700
Message-ID: <20191010225530.26400-4-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20191010225530.26400-1-sean.j.christopherson@intel.com>

Rework EEXTEND error handling to fix issues related to destroying the
enclave in response to EEXTEND failure.  At the time of EEXTEND, the
page is already visibile in the sense that it has been added to the
radix tree, and therefore will be processed by sgx_encl_destroy().  This
means the "add" part needs to be fully completed prior to invoking
sgx_encl_destroy() in order to avoid consuming half-baked state.

Move sgx_encl_destroy() to the call site of __sgx_encl_extend() so that
it is somewhat more obvious why the add needs to complete before doing
EEXTEND.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kernel/cpu/sgx/ioctl.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 61a2a7b6677e..fd4117f18564 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -351,18 +351,14 @@ static int __sgx_encl_extend(struct sgx_encl *encl,
 	for_each_set_bit(i, &mrmask, 16) {
 		ret = __eextend(sgx_epc_addr(encl->secs.epc_page),
 				sgx_epc_addr(epc_page) + (i * 0x100));
-		if (ret)
-			goto err_out;
+		if (ret) {
+			if (encls_failed(ret))
+				ENCLS_WARN(ret, "EEXTEND");
+			return -EFAULT;
+		}
 	}
 
 	return 0;
-
-err_out:
-	if (encls_failed(ret))
-		ENCLS_WARN(ret, "EEXTEND");
-
-	sgx_encl_destroy(encl);
-	return -EFAULT;
 }
 
 static int sgx_encl_add_page(struct sgx_encl *encl,
@@ -415,19 +411,24 @@ static int sgx_encl_add_page(struct sgx_encl *encl,
 	if (ret)
 		goto err_out;
 
-	ret = __sgx_encl_extend(encl, epc_page, addp->mrmask);
-	if (ret)
-		goto err_out;
-
+	/*
+	 * Complete the "add" before doing the "extend" so that the "add"
+	 * isn't in a half-baked state in the extremely unlikely scenario the
+	 * the enclave will be destroyed in response to EEXTEND failure.
+	 */
 	encl_page->encl = encl;
 	encl_page->epc_page = epc_page;
 	encl->secs_child_cnt++;
 
-	sgx_mark_page_reclaimable(encl_page->epc_page);
+	ret = __sgx_encl_extend(encl, epc_page, addp->mrmask);
+	if (ret)
+		sgx_encl_destroy(encl);
+	else
+		sgx_mark_page_reclaimable(encl_page->epc_page);
 
 	mutex_unlock(&encl->lock);
 	up_read(&current->mm->mmap_sem);
-	return 0;
+	return ret;
 
 err_out:
 	radix_tree_delete(&encl_page->encl->page_tree,
-- 
2.22.0


  parent reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-10 22:55 [PATCH for_v23 0/4] x86/sgx: Fix add page bugs Sean Christopherson
2019-10-10 22:55 ` [PATCH for_v23 1/4] x86/sgx: Pass EADD the kernel's virtual address for the source page Sean Christopherson
2019-10-10 22:55 ` [PATCH for_v23 2/4] x86/sgx: Check the validity of the source page address for EADD Sean Christopherson
2019-10-10 22:55 ` Sean Christopherson [this message]
2019-10-10 22:55 ` [PATCH for_v23 4/4] x86/sgx: Drop mmap_sem before EEXTENDing an enclave page Sean Christopherson
2019-10-14 21:03 ` [PATCH for_v23 0/4] x86/sgx: Fix add page bugs Jarkko Sakkinen
2019-10-16 16:39   ` Sean Christopherson
2019-10-17 16:25     ` Jarkko Sakkinen

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191010225530.26400-4-sean.j.christopherson@intel.com \
    --to=sean.j.christopherson@intel.com \
    --cc=jarkko.sakkinen@linux.intel.com \
    --cc=linux-sgx@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Sgx Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-sgx/0 linux-sgx/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-sgx linux-sgx/ https://lore.kernel.org/linux-sgx \
		linux-sgx@vger.kernel.org linux-sgx@archiver.kernel.org
	public-inbox-index linux-sgx

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-sgx


AGPL code for this site: git clone https://public-inbox.org/ public-inbox