From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>,
Cedric Xing <cedric.xing@intel.com>,
Stephen Smalley <sds@tycho.nsa.gov>,
James Morris <jmorris@namei.org>,
"Serge E . Hallyn" <serge@hallyn.com>,
LSM List <linux-security-module@vger.kernel.org>,
Paul Moore <paul@paul-moore.com>,
Eric Paris <eparis@parisplace.org>,
selinux@vger.kernel.org, Jethro Beekman <jethro@fortanix.com>,
Dave Hansen <dave.hansen@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
linux-sgx@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
nhorman@redhat.com, npmccallum@redhat.com,
Serge Ayoun <serge.ayoun@intel.com>,
Shay Katz-zamir <shay.katz-zamir@intel.com>,
Haitao Huang <haitao.huang@intel.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Kai Svahn <kai.svahn@intel.com>, Borislav Petkov <bp@alien8.de>,
Josh Triplett <josh@joshtriplett.org>,
Kai Huang <kai.huang@intel.com>,
David Rientjes <rientjes@google.com>,
William Roberts <william.c.roberts@intel.com>,
Philip Tricca <philip.b.tricca@intel.com>
Subject: [RFC PATCH v2 3/5] x86/sgx: Enforce noexec filesystem restriction for enclaves
Date: Wed, 5 Jun 2019 19:11:43 -0700 [thread overview]
Message-ID: <20190606021145.12604-4-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20190606021145.12604-1-sean.j.christopherson@intel.com>
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.
Checking noexec indirectly by way of VM_MAYEXEC naturally handles any
other cases that clear VM_MAYEXEC to deny execute permissions.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kernel/cpu/sgx/driver/ioctl.c | 47 +++++++++++++++++++++++---
1 file changed, 42 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/cpu/sgx/driver/ioctl.c b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
index ef5c2ce0f37b..44b2d73de7c3 100644
--- a/arch/x86/kernel/cpu/sgx/driver/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/driver/ioctl.c
@@ -577,6 +577,44 @@ 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;
+
+ if (!(prot & VM_EXEC))
+ return 0;
+
+ /* Hold mmap_sem across copy_from_user() to avoid a TOCTOU race. */
+ down_read(¤t->mm->mmap_sem);
+
+ vma = find_vma(current->mm, src);
+ if (!vma) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ /*
+ * Query VM_MAYEXEC as an indirect path_noexec() check (see do_mmap()),
+ * but with some future proofing against other cases that may deny
+ * execute permissions.
+ */
+ 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
*
@@ -616,13 +654,12 @@ static long sgx_ioc_enclave_add_page(struct file *filep, unsigned int cmd,
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)
--
2.21.0
next prev parent reply other threads:[~2019-06-06 2:12 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-06 2:11 [RFC PATCH v2 0/5] security: x86/sgx: SGX vs. LSM Sean Christopherson
2019-06-06 2:11 ` [RFC PATCH v2 1/5] mm: Introduce vm_ops->may_mprotect() Sean Christopherson
2019-06-10 15:06 ` Jarkko Sakkinen
2019-06-10 15:55 ` Sean Christopherson
2019-06-10 17:47 ` Xing, Cedric
2019-06-10 19:49 ` Sean Christopherson
2019-06-10 22:06 ` Xing, Cedric
2019-06-06 2:11 ` [RFC PATCH v2 2/5] x86/sgx: Require userspace to define enclave pages' protection bits Sean Christopherson
2019-06-10 15:27 ` Jarkko Sakkinen
2019-06-10 16:15 ` Sean Christopherson
2019-06-10 17:45 ` Jarkko Sakkinen
2019-06-10 18:17 ` Sean Christopherson
2019-06-12 19:26 ` Jarkko Sakkinen
2019-06-10 18:29 ` Xing, Cedric
2019-06-10 19:15 ` Andy Lutomirski
2019-06-10 22:28 ` Xing, Cedric
2019-06-12 0:09 ` Andy Lutomirski
2019-06-12 14:34 ` Sean Christopherson
2019-06-12 18:20 ` Xing, Cedric
2019-06-06 2:11 ` Sean Christopherson [this message]
2019-06-10 16:00 ` [RFC PATCH v2 3/5] x86/sgx: Enforce noexec filesystem restriction for enclaves Jarkko Sakkinen
2019-06-10 16:44 ` Andy Lutomirski
2019-06-11 17:21 ` Stephen Smalley
2019-06-06 2:11 ` [RFC PATCH v2 4/5] LSM: x86/sgx: Introduce ->enclave_load() hook for Intel SGX Sean Christopherson
2019-06-07 19:58 ` Stephen Smalley
2019-06-10 16:21 ` Sean Christopherson
2019-06-10 16:05 ` Jarkko Sakkinen
2019-06-06 2:11 ` [RFC PATCH v2 5/5] security/selinux: Add enclave_load() implementation Sean Christopherson
2019-06-07 21:16 ` Stephen Smalley
2019-06-10 16:46 ` Sean Christopherson
2019-06-17 16:38 ` Jarkko Sakkinen
2019-06-10 7:03 ` [RFC PATCH v1 0/3] security/x86/sgx: SGX specific LSM hooks Cedric Xing
2019-06-10 7:03 ` [RFC PATCH v1 1/3] LSM/x86/sgx: Add " Cedric Xing
2019-06-10 7:03 ` [RFC PATCH v1 2/3] LSM/x86/sgx: Implement SGX specific hooks in SELinux Cedric Xing
2019-06-11 13:40 ` Stephen Smalley
2019-06-11 22:02 ` Sean Christopherson
2019-06-12 9:32 ` Dr. Greg
2019-06-12 14:25 ` Sean Christopherson
2019-06-13 7:25 ` Dr. Greg
2019-06-12 19:30 ` Andy Lutomirski
2019-06-12 22:02 ` Sean Christopherson
2019-06-13 0:10 ` Xing, Cedric
2019-06-13 1:02 ` Xing, Cedric
2019-06-13 17:02 ` Stephen Smalley
2019-06-13 23:03 ` Xing, Cedric
2019-06-13 23:17 ` Sean Christopherson
2019-06-14 0:31 ` Xing, Cedric
2019-06-14 0:46 ` Sean Christopherson
2019-06-14 15:38 ` Sean Christopherson
2019-06-16 22:14 ` Andy Lutomirski
2019-06-17 16:49 ` Sean Christopherson
2019-06-17 17:08 ` Andy Lutomirski
2019-06-18 15:40 ` Dr. Greg
2019-06-14 17:16 ` Xing, Cedric
2019-06-14 17:45 ` Sean Christopherson
2019-06-14 17:53 ` Sean Christopherson
2019-06-14 20:01 ` Sean Christopherson
2019-06-16 22:16 ` Andy Lutomirski
2019-06-14 23:19 ` Dr. Greg
2019-06-11 22:55 ` Xing, Cedric
2019-06-13 18:00 ` Stephen Smalley
2019-06-13 19:48 ` Sean Christopherson
2019-06-13 21:09 ` Xing, Cedric
2019-06-13 21:02 ` Xing, Cedric
2019-06-14 0:37 ` Sean Christopherson
2019-06-10 7:03 ` [RFC PATCH v1 3/3] LSM/x86/sgx: Call new LSM hooks from SGX subsystem Cedric Xing
2019-06-10 17:36 ` [RFC PATCH v1 0/3] security/x86/sgx: SGX specific LSM hooks Jarkko Sakkinen
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