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From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: linux-sgx@vger.kernel.org, linux-security-module@vger.kernel.org,
	selinux@vger.kernel.org,
	Bill Roberts <william.c.roberts@intel.com>,
	Casey Schaufler <casey.schaufler@intel.com>,
	James Morris <jmorris@namei.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Cedric Xing <cedric.xing@intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Jethro Beekman <jethro@fortanix.com>,
	"Dr . Greg Wettstein" <greg@enjellic.com>,
	Stephen Smalley <sds@tycho.nsa.gov>
Subject: [RFC PATCH v4 07/12] LSM: x86/sgx: Introduce ->enclave_map() hook for Intel SGX
Date: Wed, 19 Jun 2019 15:23:56 -0700
Message-ID: <20190619222401.14942-8-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20190619222401.14942-1-sean.j.christopherson@intel.com>

enclave_map() is an SGX specific variant of file_mprotect() and
mmap_file(), and is provided so that LSMs can apply W^X restrictions to
enclaves.

Due to the nature of SGX and its Enclave Page Cache (EPC), all enclave
VMAs are backed by a single file, i.e. /dev/sgx/enclave, that must be
MAP_SHARED.  Furthermore, all enclaves need read, write and execute
VMAs.  As a result, applying W^X restrictions on /dev/sgx/enclave using
existing LSM hooks is for all intents and purposes impossible, e.g.
denying either W or X would deny access to any enclave.

Note, extensive discussion yielded no sane alternative to some form of
SGX specific LSM hook[1].

[1] https://lkml.kernel.org/r/CALCETrXf8mSK45h7sTK5Wf+pXLVn=Bjsc_RLpgO-h-qdzBRo5Q@mail.gmail.com

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kernel/cpu/sgx/driver/main.c |  9 ++++++++-
 arch/x86/kernel/cpu/sgx/encl.c        | 12 ++++++++++++
 include/linux/lsm_hooks.h             | 12 ++++++++++++
 include/linux/security.h              | 11 +++++++++++
 security/security.c                   |  7 +++++++
 5 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/sgx/driver/main.c b/arch/x86/kernel/cpu/sgx/driver/main.c
index dabfe2a7245a..4379a2fb1f82 100644
--- a/arch/x86/kernel/cpu/sgx/driver/main.c
+++ b/arch/x86/kernel/cpu/sgx/driver/main.c
@@ -133,13 +133,20 @@ static unsigned long sgx_allowed_rwx(struct sgx_encl *encl,
 static int sgx_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct sgx_encl *encl = file->private_data;
-	unsigned long allowed_rwx;
+	unsigned long allowed_rwx, prot;
 	int ret;
 
 	allowed_rwx = sgx_allowed_rwx(encl, vma);
 	if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC) & ~allowed_rwx)
 		return -EACCES;
 
+	prot = _calc_vm_trans(vma->vm_flags, VM_READ, PROT_READ) |
+	       _calc_vm_trans(vma->vm_flags, VM_WRITE, PROT_WRITE) |
+	       _calc_vm_trans(vma->vm_flags, VM_EXEC, PROT_EXEC);
+	ret = security_enclave_map(prot);
+	if (ret)
+		return ret;
+
 	ret = sgx_encl_mm_add(encl, vma->vm_mm);
 	if (ret)
 		return ret;
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index c6436bbd4a68..059d90dcaa27 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -2,6 +2,7 @@
 // Copyright(c) 2016-18 Intel Corporation.
 
 #include <linux/mm.h>
+#include <linux/security.h>
 #include <linux/shmem_fs.h>
 #include <linux/suspend.h>
 #include <linux/sched/mm.h>
@@ -387,9 +388,20 @@ static int sgx_vma_access(struct vm_area_struct *vma, unsigned long addr,
 	return ret < 0 ? ret : i;
 }
 
+#ifdef CONFIG_SECURITY
+static int sgx_vma_mprotect(struct vm_area_struct *vma, unsigned long start,
+			    unsigned long end, unsigned long prot)
+{
+	return security_enclave_map(prot);
+}
+#endif
+
 const struct vm_operations_struct sgx_vm_ops = {
 	.fault = sgx_vma_fault,
 	.access = sgx_vma_access,
+#ifdef CONFIG_SECURITY
+	.may_mprotect = sgx_vma_mprotect,
+#endif
 };
 
 /**
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 47f58cfb6a19..7c1357105e61 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1446,6 +1446,11 @@
  * @bpf_prog_free_security:
  *	Clean up the security information stored inside bpf prog.
  *
+ * Security hooks for Intel SGX enclaves.
+ *
+ * @enclave_map:
+ *	@prot contains the protection that will be applied by the kernel.
+ *	Return 0 if permission is granted.
  */
 union security_list_options {
 	int (*binder_set_context_mgr)(struct task_struct *mgr);
@@ -1807,6 +1812,10 @@ union security_list_options {
 	int (*bpf_prog_alloc_security)(struct bpf_prog_aux *aux);
 	void (*bpf_prog_free_security)(struct bpf_prog_aux *aux);
 #endif /* CONFIG_BPF_SYSCALL */
+
+#ifdef CONFIG_INTEL_SGX
+	int (*enclave_map)(unsigned long prot);
+#endif /* CONFIG_INTEL_SGX */
 };
 
 struct security_hook_heads {
@@ -2046,6 +2055,9 @@ struct security_hook_heads {
 	struct hlist_head bpf_prog_alloc_security;
 	struct hlist_head bpf_prog_free_security;
 #endif /* CONFIG_BPF_SYSCALL */
+#ifdef CONFIG_INTEL_SGX
+	struct hlist_head enclave_map;
+#endif /* CONFIG_INTEL_SGX */
 } __randomize_layout;
 
 /*
diff --git a/include/linux/security.h b/include/linux/security.h
index 659071c2e57c..6a1f54ba6794 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1829,5 +1829,16 @@ static inline void security_bpf_prog_free(struct bpf_prog_aux *aux)
 #endif /* CONFIG_SECURITY */
 #endif /* CONFIG_BPF_SYSCALL */
 
+#ifdef CONFIG_INTEL_SGX
+#ifdef CONFIG_SECURITY
+int security_enclave_map(unsigned long prot);
+#else
+static inline int security_enclave_map(unsigned long prot)
+{
+	return 0;
+}
+#endif /* CONFIG_SECURITY */
+#endif /* CONFIG_INTEL_SGX */
+
 #endif /* ! __LINUX_SECURITY_H */
 
diff --git a/security/security.c b/security/security.c
index 613a5c00e602..03951e08bdfc 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2359,3 +2359,10 @@ void security_bpf_prog_free(struct bpf_prog_aux *aux)
 	call_void_hook(bpf_prog_free_security, aux);
 }
 #endif /* CONFIG_BPF_SYSCALL */
+
+#ifdef CONFIG_INTEL_SGX
+int security_enclave_map(unsigned long prot)
+{
+	return call_int_hook(enclave_map, 0, prot);
+}
+#endif /* CONFIG_INTEL_SGX */
-- 
2.21.0


  parent reply index

Thread overview: 156+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-19 22:23 [RFC PATCH v4 00/12] security: x86/sgx: SGX vs. LSM Sean Christopherson
2019-06-19 22:23 ` [RFC PATCH v4 01/12] x86/sgx: Use mmu_notifier.release() instead of per-vma refcounting Sean Christopherson
2019-06-20 21:03   ` Jarkko Sakkinen
2019-07-08 14:57     ` Sean Christopherson
2019-07-09 16:18       ` Jarkko Sakkinen
2019-06-19 22:23 ` [RFC PATCH v4 02/12] x86/sgx: Do not naturally align MAP_FIXED address Sean Christopherson
2019-06-20 21:09   ` Jarkko Sakkinen
2019-06-20 22:09     ` Jarkko Sakkinen
2019-06-19 22:23 ` [RFC PATCH v4 03/12] selftests: x86/sgx: Mark the enclave loader as not needing an exec stack Sean Christopherson
2019-06-20 21:17   ` Jarkko Sakkinen
2019-06-19 22:23 ` [RFC PATCH v4 04/12] x86/sgx: Require userspace to define enclave pages' protection bits Sean Christopherson
2019-06-21  1:07   ` Jarkko Sakkinen
2019-06-21  1:16     ` Jarkko Sakkinen
2019-06-21 16:42   ` Xing, Cedric
2019-07-08 16:34     ` Sean Christopherson
2019-07-08 17:29       ` Xing, Cedric
2019-07-01 18:00   ` Andy Lutomirski
2019-07-01 19:22     ` Xing, Cedric
2019-06-19 22:23 ` [RFC PATCH v4 05/12] x86/sgx: Enforce noexec filesystem restriction for enclaves Sean Christopherson
2019-06-21  1:26   ` Jarkko Sakkinen
2019-07-07 19:03     ` Sean Christopherson
2019-06-19 22:23 ` [RFC PATCH v4 06/12] mm: Introduce vm_ops->may_mprotect() Sean Christopherson
2019-06-21  1:35   ` Jarkko Sakkinen
2019-06-19 22:23 ` Sean Christopherson [this message]
2019-06-21  2:28   ` [RFC PATCH v4 07/12] LSM: x86/sgx: Introduce ->enclave_map() hook for Intel SGX Jarkko Sakkinen
2019-06-21 16:54   ` Xing, Cedric
2019-06-25 20:48     ` Stephen Smalley
2019-06-27 20:29       ` Xing, Cedric
2019-07-07 18:01         ` Sean Christopherson
2019-06-19 22:23 ` [RFC PATCH v4 08/12] security/selinux: Require SGX_MAPWX to map enclave page WX Sean Christopherson
2019-06-21 17:09   ` Xing, Cedric
2019-06-25 21:05     ` Stephen Smalley
2019-06-27 20:26       ` Xing, Cedric
2019-06-25 20:19   ` Stephen Smalley
2019-06-26 12:49     ` Dr. Greg
2019-06-19 22:23 ` [RFC PATCH v4 09/12] LSM: x86/sgx: Introduce ->enclave_load() hook for Intel SGX Sean Christopherson
2019-06-21 17:05   ` Xing, Cedric
2019-06-25 21:01     ` Stephen Smalley
2019-06-25 21:49       ` Stephen Smalley
2019-06-27 19:38         ` Xing, Cedric
2019-06-19 22:23 ` [RFC PATCH v4 10/12] security/selinux: Add enclave_load() implementation Sean Christopherson
2019-06-21 21:22   ` Xing, Cedric
2019-06-25 21:09     ` Stephen Smalley
2019-06-27 20:19       ` Xing, Cedric
2019-06-28 16:16         ` Stephen Smalley
2019-06-28 21:20           ` Xing, Cedric
2019-06-29  1:15             ` Stephen Smalley
2019-07-01 18:14               ` Xing, Cedric
2019-06-29 23:41       ` Andy Lutomirski
2019-07-01 17:46         ` Xing, Cedric
2019-07-01 17:53           ` Andy Lutomirski
2019-07-01 18:54             ` Xing, Cedric
2019-07-01 19:03               ` Xing, Cedric
2019-07-01 19:32               ` Andy Lutomirski
2019-07-01 20:03                 ` Xing, Cedric
2019-07-07 18:46                   ` Sean Christopherson
2019-06-25 20:34   ` Stephen Smalley
2019-06-19 22:24 ` [RFC PATCH v4 11/12] security/apparmor: " Sean Christopherson
2019-06-19 22:24 ` [RFC PATCH v4 12/12] LSM: x86/sgx: Show line of sight to LSM support SGX2's EAUG Sean Christopherson
2019-06-21 17:18   ` Xing, Cedric
2019-07-08 14:34     ` Sean Christopherson
2019-06-21  1:32 ` [RFC PATCH v4 00/12] security: x86/sgx: SGX vs. LSM Jarkko Sakkinen
2019-06-27 18:56 ` [RFC PATCH v2 0/3] security/x86/sgx: SGX specific LSM hooks Cedric Xing
2019-07-03 23:16   ` Jarkko Sakkinen
2019-07-03 23:22     ` Jarkko Sakkinen
2019-07-03 23:23       ` Jarkko Sakkinen
2019-07-06  5:04     ` Xing, Cedric
2019-07-08 14:46       ` Jarkko Sakkinen
2019-07-07 23:41   ` [RFC PATCH v3 0/4] " Cedric Xing
2019-07-08 15:55     ` Sean Christopherson
2019-07-08 17:49       ` Xing, Cedric
2019-07-08 18:49         ` Sean Christopherson
2019-07-08 22:26           ` Xing, Cedric
2019-07-07 23:41   ` [RFC PATCH v3 1/4] x86/sgx: Add " Cedric Xing
2019-07-07 23:41   ` [RFC PATCH v3 2/4] x86/64: Call LSM hooks from SGX subsystem/module Cedric Xing
2019-07-09  1:03     ` Sean Christopherson
2019-07-07 23:41   ` [RFC PATCH v3 3/4] X86/sgx: Introduce EMA as a new LSM module Cedric Xing
2019-07-08 16:26     ` Casey Schaufler
2019-07-08 17:16       ` Xing, Cedric
2019-07-08 23:53         ` Casey Schaufler
2019-07-09 22:13           ` Xing, Cedric
2019-07-10  0:10             ` Casey Schaufler
2019-07-10  0:55               ` Xing, Cedric
2019-07-10 21:14                 ` Casey Schaufler
2019-07-11 13:51                 ` Stephen Smalley
2019-07-11 15:12                   ` Sean Christopherson
2019-07-11 16:11                     ` Stephen Smalley
2019-07-11 16:25                       ` Sean Christopherson
2019-07-11 16:32                         ` Stephen Smalley
2019-07-11 23:41                           ` Xing, Cedric
2019-07-07 23:41   ` [RFC PATCH v3 4/4] x86/sgx: Implement SGX specific hooks in SELinux Cedric Xing
2019-07-09  1:33     ` Sean Christopherson
2019-07-09 21:26       ` Xing, Cedric
2019-07-10 15:49     ` Sean Christopherson
2019-07-10 16:08       ` Jethro Beekman
2019-07-10 18:16         ` Xing, Cedric
2019-07-10 17:54       ` Xing, Cedric
2019-06-27 18:56 ` [RFC PATCH v2 1/3] x86/sgx: Add SGX specific LSM hooks Cedric Xing
2019-06-27 22:06   ` Casey Schaufler
2019-06-27 22:52     ` Xing, Cedric
2019-06-27 23:37       ` Casey Schaufler
2019-06-28  0:47         ` Xing, Cedric
2019-06-28 17:22           ` Casey Schaufler
2019-06-28 22:29             ` Xing, Cedric
2019-06-29  1:37             ` Stephen Smalley
2019-06-29 21:35               ` Casey Schaufler
2019-07-01 17:57                 ` Xing, Cedric
2019-07-01 19:53                   ` Casey Schaufler
2019-07-01 21:45                     ` Xing, Cedric
2019-07-01 23:11                       ` Casey Schaufler
2019-07-02  7:42                         ` Xing, Cedric
2019-07-02 15:44                           ` Casey Schaufler
2019-07-03  9:46                             ` Dr. Greg
2019-07-03 15:32                               ` Casey Schaufler
2019-07-07 13:30                                 ` Dr. Greg
2019-07-09  0:02                                   ` Casey Schaufler
2019-07-09  1:52                                     ` Sean Christopherson
2019-07-09 21:16                                       ` Xing, Cedric
2019-07-11 10:22                                     ` Dr. Greg
2019-07-15 22:23                                       ` Andy Lutomirski
2019-06-28 16:37   ` Stephen Smalley
2019-06-28 21:53     ` Xing, Cedric
2019-06-29  1:22       ` Stephen Smalley
2019-07-01 18:02         ` Xing, Cedric
2019-06-29 23:46   ` Andy Lutomirski
2019-07-01 17:11     ` Xing, Cedric
2019-07-01 17:58       ` Andy Lutomirski
2019-07-01 18:31         ` Xing, Cedric
2019-07-01 19:36           ` Andy Lutomirski
2019-07-01 19:56             ` Xing, Cedric
2019-07-02  2:29               ` Andy Lutomirski
2019-07-02  6:35                 ` Xing, Cedric
2019-06-27 18:56 ` [RFC PATCH v2 2/3] x86/sgx: Call LSM hooks from SGX subsystem/module Cedric Xing
2019-06-27 18:56 ` [RFC PATCH v2 3/3] x86/sgx: Implement SGX specific hooks in SELinux Cedric Xing
2019-07-05 16:05 ` [RFC PATCH v4 00/12] security: x86/sgx: SGX vs. LSM Jarkko Sakkinen
2019-07-08 17:29   ` Sean Christopherson
2019-07-08 17:33     ` Xing, Cedric
2019-07-09 16:22     ` Jarkko Sakkinen
2019-07-09 17:09       ` Sean Christopherson
2019-07-09 20:41         ` Xing, Cedric
2019-07-09 22:25           ` Sean Christopherson
2019-07-09 23:11             ` Xing, Cedric
2019-07-10 16:57               ` Sean Christopherson
2019-07-10 20:19         ` Jarkko Sakkinen
2019-07-10 20:31           ` Sean Christopherson
2019-07-11  9:06             ` Jarkko Sakkinen
2019-07-10 22:00           ` Jarkko Sakkinen
2019-07-10 22:16         ` Jarkko Sakkinen
2019-07-10 23:16           ` Xing, Cedric
2019-07-11  9:26             ` Jarkko Sakkinen
2019-07-11 14:32               ` Stephen Smalley
2019-07-11 17:51                 ` Jarkko Sakkinen
2019-07-12  0:08                   ` Xing, Cedric
2019-07-10  1:28     ` Dr. Greg
2019-07-10  2:04       ` Xing, Cedric
2019-07-10  3:21     ` Jethro Beekman

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