From: Jarkko Sakkinen <jarkko@kernel.org>
To: x86@kernel.org, linux-sgx@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Jarkko Sakkinen <jarkko@kernel.org>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Matthew Wilcox <willy@infradead.org>,
Jethro Beekman <jethro@fortanix.com>,
andriy.shevchenko@linux.intel.com, asapek@google.com,
bp@alien8.de, cedric.xing@intel.com, chenalexchen@google.com,
conradparker@google.com, cyhanish@google.com,
dave.hansen@intel.com, haitao.huang@intel.com,
kai.huang@intel.com, kai.svahn@intel.com, kmoy@google.com,
ludloff@google.com, luto@kernel.org, nhorman@redhat.com,
npmccallum@redhat.com, puiterwijk@redhat.com,
rientjes@google.com, sean.j.christopherson@intel.com,
tglx@linutronix.de, yaozhangx@google.com, mikko.ylinen@intel.com
Subject: [PATCH v41 22/24] x86/sgx: Add ptrace() support for the SGX driver
Date: Fri, 13 Nov 2020 00:01:33 +0200 [thread overview]
Message-ID: <20201112220135.165028-23-jarkko@kernel.org> (raw)
In-Reply-To: <20201112220135.165028-1-jarkko@kernel.org>
Enclave memory is normally inaccessible from outside the enclave. This
makes enclaves hard to debug. However, enclaves can be put in a debug mode
when they are being built. In debug enclaves data *can* be read and/or
written by using the ENCLS[EDBGRD] and ENCLS[EDBGWR] functions.
This is obviously only for debugging and destroys all the protections
afforded to normal enclaves. But, enclaves know their own debug status and
can adjust their behavior appropriately.
Add a vm_ops->access() implementation which can be used to read and write
memory inside debug enclaves. This is typically used via ptrace() APIs.
Cc: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Tested-by: Jethro Beekman <jethro@fortanix.com> # v40
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
Changes from v39:
* Check only for SGX_ENCL_DEBUG in sgx_vma_access(), so that a debug
enclave's memory can read and written at any phase of its life-cycle.
arch/x86/kernel/cpu/sgx/encl.c | 111 +++++++++++++++++++++++++++++++++
1 file changed, 111 insertions(+)
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 141424657718..94e7e41e6adf 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -272,10 +272,121 @@ static int sgx_vma_mprotect(struct vm_area_struct *vma, unsigned long start,
return sgx_encl_may_map(vma->vm_private_data, start, end, newflags);
}
+static int sgx_encl_debug_read(struct sgx_encl *encl, struct sgx_encl_page *page,
+ unsigned long addr, void *data)
+{
+ unsigned long offset = addr & ~PAGE_MASK;
+ int ret;
+
+
+ ret = __edbgrd(sgx_get_epc_virt_addr(page->epc_page) + offset, data);
+ if (ret)
+ return -EIO;
+
+ return 0;
+}
+
+static int sgx_encl_debug_write(struct sgx_encl *encl, struct sgx_encl_page *page,
+ unsigned long addr, void *data)
+{
+ unsigned long offset = addr & ~PAGE_MASK;
+ int ret;
+
+ ret = __edbgwr(sgx_get_epc_virt_addr(page->epc_page) + offset, data);
+ if (ret)
+ return -EIO;
+
+ return 0;
+}
+
+/*
+ * Load an enclave page to EPC if required, and take encl->lock.
+ */
+static struct sgx_encl_page *sgx_encl_reserve_page(struct sgx_encl *encl,
+ unsigned long addr,
+ unsigned long vm_flags)
+{
+ struct sgx_encl_page *entry;
+
+ for ( ; ; ) {
+ mutex_lock(&encl->lock);
+
+ entry = sgx_encl_load_page(encl, addr, vm_flags);
+ if (PTR_ERR(entry) != -EBUSY)
+ break;
+
+ mutex_unlock(&encl->lock);
+ }
+
+ if (IS_ERR(entry))
+ mutex_unlock(&encl->lock);
+
+ return entry;
+}
+
+static int sgx_vma_access(struct vm_area_struct *vma, unsigned long addr,
+ void *buf, int len, int write)
+{
+ struct sgx_encl *encl = vma->vm_private_data;
+ struct sgx_encl_page *entry = NULL;
+ char data[sizeof(unsigned long)];
+ unsigned long align;
+ int offset;
+ int cnt;
+ int ret = 0;
+ int i;
+
+ /*
+ * If process was forked, VMA is still there but vm_private_data is set
+ * to NULL.
+ */
+ if (!encl)
+ return -EFAULT;
+
+ if (!test_bit(SGX_ENCL_DEBUG, &encl->flags))
+ return -EFAULT;
+
+ for (i = 0; i < len; i += cnt) {
+ entry = sgx_encl_reserve_page(encl, (addr + i) & PAGE_MASK,
+ vma->vm_flags);
+ if (IS_ERR(entry)) {
+ ret = PTR_ERR(entry);
+ break;
+ }
+
+ align = ALIGN_DOWN(addr + i, sizeof(unsigned long));
+ offset = (addr + i) & (sizeof(unsigned long) - 1);
+ cnt = sizeof(unsigned long) - offset;
+ cnt = min(cnt, len - i);
+
+ ret = sgx_encl_debug_read(encl, entry, align, data);
+ if (ret)
+ goto out;
+
+ if (write) {
+ memcpy(data + offset, buf + i, cnt);
+ ret = sgx_encl_debug_write(encl, entry, align, data);
+ if (ret)
+ goto out;
+ } else {
+ memcpy(buf + i, data + offset, cnt);
+ }
+
+out:
+ mutex_unlock(&encl->lock);
+
+ if (ret)
+ break;
+ }
+
+ return ret < 0 ? ret : i;
+}
+
const struct vm_operations_struct sgx_vm_ops = {
.fault = sgx_vma_fault,
.mprotect = sgx_vma_mprotect,
.open = sgx_vma_open,
+ .access = sgx_vma_access,
};
/**
--
2.27.0
next prev parent reply other threads:[~2020-11-12 22:04 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 22:01 [PATCH v41 00/24] Intel SGX foundations Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 01/24] x86/sgx: Add SGX architectural data structures Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 02/24] x86/sgx: Add wrappers for ENCLS functions Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 03/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 04/24] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 05/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen
2020-11-16 22:25 ` [PATCH] x86/sgx: clarify 'laundry_list' locking Dave Hansen
2020-11-17 19:29 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 06/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 07/24] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 08/24] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 09/24] x86/sgx: Add SGX page allocator functions Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 10/24] mm: Add 'mprotect' hook to struct vm_operations_struct Jarkko Sakkinen
2020-11-13 10:25 ` Mel Gorman
2020-11-17 18:16 ` Jarkko Sakkinen
2020-11-15 17:08 ` Dr. Greg
2020-11-15 17:32 ` Matthew Wilcox
2020-11-15 18:36 ` Dave Hansen
2020-11-16 10:09 ` Mel Gorman
2020-11-17 19:15 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 11/24] x86/sgx: Add SGX misc driver interface Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE Jarkko Sakkinen
[not found] ` <20201115044044.11040-1-hdanton@sina.com>
2020-11-17 17:35 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 13/24] x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 14/24] x86/sgx: Add SGX_IOC_ENCLAVE_INIT Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 15/24] x86/sgx: Add SGX_IOC_ENCLAVE_PROVISION Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 16/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 17/24] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 18/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 19/24] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-11-17 13:14 ` Borislav Petkov
2020-11-17 19:41 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 20/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-11-16 18:19 ` Shuah Khan
2020-11-17 13:22 ` Borislav Petkov
2020-11-17 19:42 ` Jarkko Sakkinen
2020-11-17 17:26 ` Borislav Petkov
2020-11-17 21:27 ` Jarkko Sakkinen
2020-11-17 21:38 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 21/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-11-12 22:01 ` Jarkko Sakkinen [this message]
2020-11-12 22:01 ` [PATCH v41 23/24] docs: x86/sgx: Document SGX kernel architecture Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 24/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2020-11-16 16:55 ` [PATCH v41 00/24] Intel SGX foundations Borislav Petkov
2020-11-16 17:21 ` Dave Hansen
2020-11-16 17:28 ` Borislav Petkov
2020-11-17 19:20 ` Jarkko Sakkinen
[not found] ` <20201114084211.5284-1-hdanton@sina.com>
2020-11-16 18:33 ` [PATCH v41 05/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Dave Hansen
[not found] ` <20201115040127.7804-1-hdanton@sina.com>
2020-11-16 21:11 ` [PATCH v41 11/24] x86/sgx: Add SGX misc driver interface Dave Hansen
[not found] ` <20201114090708.8684-1-hdanton@sina.com>
2020-11-17 18:12 ` [PATCH v41 06/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
[not found] ` <20201114093256.7800-1-hdanton@sina.com>
2020-11-17 18:14 ` [PATCH v41 09/24] x86/sgx: Add SGX page allocator functions Jarkko Sakkinen
[not found] ` <20201115030548.1572-1-hdanton@sina.com>
2020-11-17 18:22 ` [PATCH v41 10/24] mm: Add 'mprotect' hook to struct vm_operations_struct Jarkko Sakkinen
2020-12-15 5:38 ` [PATCH v41 00/24] Intel SGX foundations Hui, Chunyang
2020-12-15 5:43 ` Hui, Chunyang
2020-12-15 15:58 ` Jarkko Sakkinen
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