From: Alexandre Chartre <alexandre.chartre@oracle.com>
To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
hpa@zytor.com, x86@kernel.org, dave.hansen@linux.intel.com,
luto@kernel.org, peterz@infradead.org,
linux-kernel@vger.kernel.org, thomas.lendacky@amd.com,
jroedel@suse.de
Cc: konrad.wilk@oracle.com, jan.setjeeilers@oracle.com,
junaids@google.com, oweisse@google.com, rppt@linux.vnet.ibm.com,
graf@amazon.de, mgross@linux.intel.com, kuzuno@gmail.com,
alexandre.chartre@oracle.com
Subject: [RFC][PATCH v2 11/21] x86/pti: Extend PTI user mappings
Date: Mon, 16 Nov 2020 15:47:47 +0100 [thread overview]
Message-ID: <20201116144757.1920077-12-alexandre.chartre@oracle.com> (raw)
In-Reply-To: <20201116144757.1920077-1-alexandre.chartre@oracle.com>
Extend PTI user mappings so that more kernel entry code can be executed
with the user page-table. To do so, we need to map syscall and interrupt
entry code, per cpu offsets (__per_cpu_offset, which is used some in
entry code), the stack canary, and the PTI stack (which is defined per
task).
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
arch/x86/entry/entry_64.S | 2 --
arch/x86/mm/pti.c | 19 +++++++++++++++++++
kernel/fork.c | 22 ++++++++++++++++++++++
3 files changed, 41 insertions(+), 2 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 6e0b5b010e0b..458af12ed9a1 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -274,7 +274,6 @@ SYM_FUNC_END(__switch_to_asm)
* rbx: kernel thread func (NULL for user thread)
* r12: kernel thread arg
*/
-.pushsection .text, "ax"
SYM_CODE_START(ret_from_fork)
UNWIND_HINT_REGS
movq %rsp, %rdi /* pt_regs */
@@ -284,7 +283,6 @@ SYM_CODE_START(ret_from_fork)
call return_from_fork /* returns with IRQs disabled */
jmp swapgs_restore_regs_and_return_to_usermode
SYM_CODE_END(ret_from_fork)
-.popsection
.macro DEBUG_ENTRY_ASSERT_IRQS_OFF
#ifdef CONFIG_DEBUG_ENTRY
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 71ca245d7b38..e4c6cb4a4840 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -449,6 +449,7 @@ static void __init pti_clone_percpu_page(void *addr)
*/
static void __init pti_clone_user_shared(void)
{
+ unsigned long start, end;
unsigned int cpu;
pti_clone_p4d(CPU_ENTRY_AREA_BASE);
@@ -465,7 +466,16 @@ static void __init pti_clone_user_shared(void)
*/
pti_clone_percpu_page(&per_cpu(cpu_tss_rw, cpu));
+ /*
+ * Map fixed_percpu_data to get the stack canary.
+ */
+ if (IS_ENABLED(CONFIG_STACKPROTECTOR))
+ pti_clone_percpu_page(&per_cpu(fixed_percpu_data, cpu));
}
+
+ start = (unsigned long)__per_cpu_offset;
+ end = start + sizeof(__per_cpu_offset);
+ pti_clone_init_pgtable(start, end, PTI_CLONE_PTE);
}
#else /* CONFIG_X86_64 */
@@ -505,6 +515,15 @@ static void pti_clone_entry_text(void)
pti_clone_init_pgtable((unsigned long) __entry_text_start,
(unsigned long) __entry_text_end,
PTI_CLONE_PMD);
+
+ /*
+ * Syscall and interrupt entry code (which is in the noinstr
+ * section) will be entered with the user page-table, so that
+ * code has to be mapped in.
+ */
+ pti_clone_init_pgtable((unsigned long) __noinstr_text_start,
+ (unsigned long) __noinstr_text_end,
+ PTI_CLONE_PMD);
}
/*
diff --git a/kernel/fork.c b/kernel/fork.c
index 6d266388d380..31cd77dbdba3 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -999,6 +999,25 @@ static void mm_init_uprobes_state(struct mm_struct *mm)
#endif
}
+static void mm_map_task(struct mm_struct *mm, struct task_struct *tsk)
+{
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+ unsigned long addr;
+
+ if (!tsk || !static_cpu_has(X86_FEATURE_PTI))
+ return;
+
+ /*
+ * Map the task stack after the kernel stack into the user
+ * address space, so that this stack can be used when entering
+ * syscall or interrupt from user mode.
+ */
+ BUG_ON(!task_stack_page(tsk));
+ addr = (unsigned long)task_top_of_kernel_stack(tsk);
+ pti_clone_pgtable(mm, addr, addr + KERNEL_STACK_SIZE, PTI_CLONE_PTE);
+#endif
+}
+
static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
struct user_namespace *user_ns)
{
@@ -1043,6 +1062,8 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
if (init_new_context(p, mm))
goto fail_nocontext;
+ mm_map_task(mm, p);
+
mm->user_ns = get_user_ns(user_ns);
return mm;
@@ -1404,6 +1425,7 @@ static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
vmacache_flush(tsk);
if (clone_flags & CLONE_VM) {
+ mm_map_task(oldmm, tsk);
mmget(oldmm);
mm = oldmm;
goto good_mm;
--
2.18.4
next prev parent reply other threads:[~2020-11-16 14:49 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-16 14:47 [RFC][PATCH v2 00/21] x86/pti: Defer CR3 switch to C code Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 01/21] x86/syscall: Add wrapper for invoking syscall function Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 02/21] x86/entry: Update asm_call_on_stack to support more function arguments Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 03/21] x86/entry: Consolidate IST entry from userspace Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 04/21] x86/sev-es: Define a setup stack function for the VC idtentry Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 05/21] x86/entry: Implement ret_from_fork body with C code Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 06/21] x86/pti: Provide C variants of PTI switch CR3 macros Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 07/21] x86/entry: Fill ESPFIX stack using C code Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 08/21] x86/pti: Introduce per-task PTI trampoline stack Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 09/21] x86/pti: Function to clone page-table entries from a specified mm Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 10/21] x86/pti: Function to map per-cpu page-table entry Alexandre Chartre
2020-11-16 14:47 ` Alexandre Chartre [this message]
2020-11-16 19:48 ` [RFC][PATCH v2 11/21] x86/pti: Extend PTI user mappings Andy Lutomirski
2020-11-16 20:21 ` Alexandre Chartre
2020-11-16 23:06 ` Andy Lutomirski
2020-11-17 8:42 ` Alexandre Chartre
2020-11-17 15:49 ` Andy Lutomirski
2020-11-19 19:15 ` Thomas Gleixner
2020-11-16 14:47 ` [RFC][PATCH v2 12/21] x86/pti: Use PTI stack instead of trampoline stack Alexandre Chartre
2020-11-16 16:57 ` Andy Lutomirski
2020-11-16 18:10 ` Alexandre Chartre
2020-11-16 18:34 ` Andy Lutomirski
2020-11-16 19:37 ` Alexandre Chartre
2020-11-17 15:09 ` Alexandre Chartre
2020-11-17 15:52 ` Andy Lutomirski
2020-11-17 17:01 ` Alexandre Chartre
2020-11-19 1:49 ` Andy Lutomirski
2020-11-19 8:05 ` Alexandre Chartre
2020-11-19 12:06 ` Alexandre Chartre
2020-11-19 16:06 ` Andy Lutomirski
2020-11-19 17:02 ` Alexandre Chartre
2020-11-16 21:24 ` David Laight
2020-11-17 8:27 ` Alexandre Chartre
2020-11-19 19:10 ` Thomas Gleixner
2020-11-19 19:55 ` Alexandre Chartre
2020-11-19 21:20 ` Thomas Gleixner
2020-11-24 7:20 ` [x86/pti] 5da9e742d1: PANIC:double_fault kernel test robot
2020-11-16 14:47 ` [RFC][PATCH v2 13/21] x86/pti: Execute syscall functions on the kernel stack Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 14/21] x86/pti: Execute IDT handlers " Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 15/21] x86/pti: Execute IDT handlers with error code " Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 16/21] x86/pti: Execute system vector handlers " Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 17/21] x86/pti: Execute page fault handler " Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 18/21] x86/pti: Execute NMI " Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 19/21] x86/pti: Defer CR3 switch to C code for IST entries Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 20/21] x86/pti: Defer CR3 switch to C code for non-IST and syscall entries Alexandre Chartre
2020-11-16 14:47 ` [RFC][PATCH v2 21/21] x86/pti: Use a different stack canary with the user and kernel page-table Alexandre Chartre
2020-11-16 16:56 ` Andy Lutomirski
2020-11-16 18:34 ` Alexandre Chartre
2020-11-16 20:17 ` [RFC][PATCH v2 00/21] x86/pti: Defer CR3 switch to C code Borislav Petkov
2020-11-17 7:56 ` Alexandre Chartre
2020-11-17 16:55 ` Borislav Petkov
2020-11-17 18:12 ` Alexandre Chartre
2020-11-17 18:28 ` Borislav Petkov
2020-11-17 19:02 ` Alexandre Chartre
2020-11-17 21:23 ` Borislav Petkov
2020-11-18 7:08 ` Alexandre Chartre
2020-11-17 21:26 ` Borislav Petkov
2020-11-18 7:41 ` Alexandre Chartre
2020-11-18 9:30 ` David Laight
2020-11-18 10:29 ` Alexandre Chartre
2020-11-18 13:22 ` David Laight
2020-11-18 17:15 ` Alexandre Chartre
2020-11-18 11:29 ` Borislav Petkov
2020-11-18 19:37 ` Alexandre Chartre
2020-11-16 20:24 ` Borislav Petkov
2020-11-17 8:19 ` Alexandre Chartre
2020-11-17 17:07 ` Borislav Petkov
2020-11-17 18:24 ` Alexandre Chartre
2020-11-19 19:32 ` Thomas Gleixner
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