Implement memory encryption with a new system call that is an
extension of the legacy mprotect() system call.
In encrypt_mprotect the caller must pass a handle to a previously
allocated and programmed encryption key. Validate the key and store
the keyid bits in the vm_page_prot for each VMA in the protection
range.
Signed-off-by: Alison Schofield <alison.schofield@xxxxxxxxx>
---
fs/exec.c | 4 ++--
include/linux/key.h | 2 ++
include/linux/mm.h | 3 ++-
mm/mprotect.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++-----
4 files changed, 67 insertions(+), 9 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index a1a246062561..b681a413db9c 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -754,8 +754,8 @@ int setup_arg_pages(struct linux_binprm *bprm,
vm_flags |= mm->def_flags;
vm_flags |= VM_STACK_INCOMPLETE_SETUP;
- ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
- vm_flags);
+ ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, vm_flags,
+ -1);
if (ret)
goto out_unlock;
BUG_ON(prev != vma);
diff --git a/include/linux/key.h b/include/linux/key.h
index e58ee10f6e58..fb8a7d5f6149 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -346,6 +346,8 @@ static inline key_serial_t key_serial(const struct key *key)
extern void key_set_timeout(struct key *, unsigned);
+extern key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
+ key_perm_t perm);
/*
* The permissions required on a key that we're looking up.
*/
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ac85c0805761..0f9422c7841e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1579,7 +1579,8 @@ extern unsigned long change_protection(struct vm_area_struct *vma, unsigned long
int dirty_accountable, int prot_numa);
extern int mprotect_fixup(struct vm_area_struct *vma,
struct vm_area_struct **pprev, unsigned long start,
- unsigned long end, unsigned long newflags);
+ unsigned long end, unsigned long newflags,
+ int newkeyid);
/*
* doesn't attempt to fault and will return short.
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 56e64ef7931e..6c2e1106525c 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -28,14 +28,17 @@
#include <linux/ksm.h>
#include <linux/uaccess.h>
#include <linux/mm_inline.h>
+#include <linux/key.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
#include <asm/tlbflush.h>
+#include <asm/mktme.h>
#include "internal.h"
#define NO_PKEY -1
+#define NO_KEYID -1
static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end, pgprot_t newprot,
@@ -310,7 +313,8 @@ unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
int
mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
- unsigned long start, unsigned long end, unsigned long newflags)
+ unsigned long start, unsigned long end, unsigned long newflags,
+ int newkeyid)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long oldflags = vma->vm_flags;
@@ -320,10 +324,24 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
int error;
int dirty_accountable = 0;
+ /*
+ * Flags match and Keyids match or we have NO_KEYID.
+ * This _fixup is usually called from do_mprotect_ext() except
+ * for one special case: caller fs/exec.c/setup_arg_pages()
+ * In that case, newkeyid is passed as -1 (NO_KEYID).
+ */
+ if (newflags == oldflags &&
+ (newkeyid == vma_keyid(vma) || newkeyid == NO_KEYID)) {
+ *pprev = vma;
+ return 0;
+ }
+ /* Flags match and Keyid changes */
if (newflags == oldflags) {
+ mprotect_set_encrypt(vma, newkeyid);
*pprev = vma;
return 0;
}
+ /* Flags and Keyids both change, continue. */
/*
* If we make a private mapping writable we increase our commit;
@@ -373,6 +391,8 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
}
success:
+ if (newkeyid != NO_KEYID)
+ mprotect_set_encrypt(vma, newkeyid);
/*
* vm_flags and vm_page_prot are protected by the mmap_sem
* held in write mode.
@@ -404,10 +424,15 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
}
/*
- * When pkey==NO_PKEY we get legacy mprotect behavior here.
+ * do_mprotect_ext() supports the legacy mprotect behavior plus extensions
+ * for protection keys and memory encryption keys. These extensions are
+ * mutually exclusive and the behavior is:
+ * (pkey==NO_PKEY && keyid==NO_KEYID) ==> legacy mprotect
+ * (pkey is valid) ==> legacy mprotect plus protection key extensions
+ * (keyid is valid) ==> legacy mprotect plus encryption key extensions
*/
static int do_mprotect_ext(unsigned long start, size_t len,
- unsigned long prot, int pkey)
+ unsigned long prot, int pkey, int keyid)
{
unsigned long nstart, end, tmp, reqprot;
struct vm_area_struct *vma, *prev;
@@ -505,7 +530,8 @@ static int do_mprotect_ext(unsigned long start, size_t len,
tmp = vma->vm_end;
if (tmp > end)
tmp = end;
- error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
+ error = mprotect_fixup(vma, &prev, nstart, tmp, newflags,
+ keyid);
if (error)
goto out;
nstart = tmp;
@@ -530,7 +556,7 @@ static int do_mprotect_ext(unsigned long start, size_t len,
SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
unsigned long, prot)
{
- return do_mprotect_ext(start, len, prot, NO_PKEY);
+ return do_mprotect_ext(start, len, prot, NO_PKEY, NO_KEYID);
}
#ifdef CONFIG_ARCH_HAS_PKEYS
@@ -538,7 +564,7 @@ SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
unsigned long, prot, int, pkey)
{
- return do_mprotect_ext(start, len, prot, pkey);
+ return do_mprotect_ext(start, len, prot, pkey, NO_KEYID);
}
SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
@@ -587,3 +613,32 @@ SYSCALL_DEFINE1(pkey_free, int, pkey)
}
#endif /* CONFIG_ARCH_HAS_PKEYS */
+
+#ifdef CONFIG_X86_INTEL_MKTME
+
+SYSCALL_DEFINE4(encrypt_mprotect, unsigned long, start, size_t, len,
+ unsigned long, prot, key_serial_t, serial)
+{
+ key_ref_t key_ref;
+ int ret, keyid;
+
+ /* TODO MKTME key service must be initialized */
+
+ key_ref = lookup_user_key(serial, 0, KEY_NEED_VIEW);
+ if (IS_ERR(key_ref))
+ return PTR_ERR(key_ref);
+
+ mktme_map_lock();
+ keyid = mktme_map_keyid_from_serial(serial);
+ if (!keyid) {
+ mktme_map_unlock();
+ key_ref_put(key_ref);
+ return -EINVAL;
+ }
+ ret = do_mprotect_ext(start, len, prot, NO_PKEY, keyid);
+ mktme_map_unlock();
+ key_ref_put(key_ref);
+ return ret;
+}
+
+#endif /* CONFIG_X86_INTEL_MKTME */
--
2.14.1
