From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org, Borislav Petkov <bp@alien8.de>,
Nadav Amit <nadav.amit@gmail.com>,
Kees Cook <keescook@chromium.org>,
Brian Gerst <brgerst@gmail.com>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Josh Poimboeuf <jpoimboe@redhat.com>, Jann Horn <jann@thejh.net>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Andy Lutomirski <luto@kernel.org>,
Oleg Nesterov <oleg@redhat.com>
Subject: [PATCH v5 07/32] fork: Add generic vmalloced stack support
Date: Mon, 11 Jul 2016 13:53:40 -0700 [thread overview]
Message-ID: <51f37059777910f989486657d1e27ded4c7edad2.1468270393.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1468270393.git.luto@kernel.org>
In-Reply-To: <cover.1468270393.git.luto@kernel.org>
If CONFIG_VMAP_STACK is selected, kernel stacks are allocated with
vmalloc_node.
grsecurity has had a similar feature (called
GRKERNSEC_KSTACKOVERFLOW) for a long time.
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/Kconfig | 33 +++++++++++++
arch/ia64/include/asm/thread_info.h | 2 +-
include/linux/sched.h | 15 ++++++
kernel/fork.c | 96 +++++++++++++++++++++++++++++--------
4 files changed, 125 insertions(+), 21 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index 15996290fed4..14398fcf8292 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -661,4 +661,37 @@ config ARCH_NO_COHERENT_DMA_MMAP
config CPU_NO_EFFICIENT_FFS
def_bool n
+config HAVE_ARCH_VMAP_STACK
+ def_bool n
+ help
+ An arch should select this symbol if it can support kernel stacks
+ in vmalloc space. This means:
+
+ - vmalloc space must be large enough to hold many kernel stacks.
+ This may rule out many 32-bit architectures.
+
+ - Stacks in vmalloc space need to work reliably. For example, if
+ vmap page tables are created on demand, either this mechanism
+ needs to work while the stack points to a virtual address with
+ unpopulated page tables or arch code (switch_to and switch_mm,
+ most likely) needs to ensure that the stack's page table entries
+ are populated before running on a possibly unpopulated stack.
+
+ - If the stack overflows into a guard page, something reasonable
+ should happen. The definition of "reasonable" is flexible, but
+ instantly rebooting without logging anything would be unfriendly.
+
+config VMAP_STACK
+ bool "Use a virtually-mapped stack"
+ depends on HAVE_ARCH_VMAP_STACK && !KASAN
+ ---help---
+ Enable this if you want the use virtually-mapped kernel stacks
+ with guard pages. This causes kernel stack overflows to be
+ caught immediately rather than causing difficult-to-diagnose
+ corruption.
+
+ This is presently incompatible with KASAN because KASAN expects
+ the stack to map directly to the KASAN shadow map using a formula
+ that is incorrect if the stack is in vmalloc space.
+
source "kernel/gcov/Kconfig"
diff --git a/arch/ia64/include/asm/thread_info.h b/arch/ia64/include/asm/thread_info.h
index d1212b84fb83..f0a72e98e5a4 100644
--- a/arch/ia64/include/asm/thread_info.h
+++ b/arch/ia64/include/asm/thread_info.h
@@ -56,7 +56,7 @@ struct thread_info {
#define alloc_thread_stack_node(tsk, node) ((unsigned long *) 0)
#define task_thread_info(tsk) ((struct thread_info *) 0)
#endif
-#define free_thread_stack(ti) /* nothing */
+#define free_thread_stack(tsk) /* nothing */
#define task_stack_page(tsk) ((void *)(tsk))
#define __HAVE_THREAD_FUNCTIONS
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 253538f29ade..26869dba21f1 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1918,6 +1918,9 @@ struct task_struct {
#ifdef CONFIG_MMU
struct task_struct *oom_reaper_list;
#endif
+#ifdef CONFIG_VMAP_STACK
+ struct vm_struct *stack_vm_area;
+#endif
/* CPU-specific state of this task */
struct thread_struct thread;
/*
@@ -1934,6 +1937,18 @@ extern int arch_task_struct_size __read_mostly;
# define arch_task_struct_size (sizeof(struct task_struct))
#endif
+#ifdef CONFIG_VMAP_STACK
+static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
+{
+ return t->stack_vm_area;
+}
+#else
+static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
+{
+ return NULL;
+}
+#endif
+
/* Future-safe accessor for struct task_struct's cpus_allowed. */
#define tsk_cpus_allowed(tsk) (&(tsk)->cpus_allowed)
diff --git a/kernel/fork.c b/kernel/fork.c
index 146c9840c079..d2a64a0413be 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -158,19 +158,39 @@ void __weak arch_release_thread_stack(unsigned long *stack)
* Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
* kmemcache based allocator.
*/
-# if THREAD_SIZE >= PAGE_SIZE
-static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
- int node)
+# if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
+static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
{
+#ifdef CONFIG_VMAP_STACK
+ void *stack = __vmalloc_node_range(THREAD_SIZE, THREAD_SIZE,
+ VMALLOC_START, VMALLOC_END,
+ THREADINFO_GFP | __GFP_HIGHMEM,
+ PAGE_KERNEL,
+ 0, node,
+ __builtin_return_address(0));
+
+ /*
+ * We can't call find_vm_area() in interrupt context, and
+ * free_thread_stack can be called in interrupt context, so cache
+ * the vm_struct.
+ */
+ if (stack)
+ tsk->stack_vm_area = find_vm_area(stack);
+ return stack;
+#else
struct page *page = alloc_kmem_pages_node(node, THREADINFO_GFP,
THREAD_SIZE_ORDER);
return page ? page_address(page) : NULL;
+#endif
}
-static inline void free_thread_stack(unsigned long *stack)
+static inline void free_thread_stack(struct task_struct *tsk)
{
- free_kmem_pages((unsigned long)stack, THREAD_SIZE_ORDER);
+ if (task_stack_vm_area(tsk))
+ vfree(tsk->stack);
+ else
+ free_kmem_pages((unsigned long)tsk->stack, THREAD_SIZE_ORDER);
}
# else
static struct kmem_cache *thread_stack_cache;
@@ -181,9 +201,9 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
return kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
}
-static void free_thread_stack(unsigned long *stack)
+static void free_thread_stack(struct task_struct *tsk)
{
- kmem_cache_free(thread_stack_cache, stack);
+ kmem_cache_free(thread_stack_cache, tsk->stack);
}
void thread_stack_cache_init(void)
@@ -213,24 +233,47 @@ struct kmem_cache *vm_area_cachep;
/* SLAB cache for mm_struct structures (tsk->mm) */
static struct kmem_cache *mm_cachep;
-static void account_kernel_stack(unsigned long *stack, int account)
+static void account_kernel_stack(struct task_struct *tsk, int account)
{
- /* All stack pages are in the same zone and belong to the same memcg. */
- struct page *first_page = virt_to_page(stack);
+ void *stack = task_stack_page(tsk);
+ struct vm_struct *vm = task_stack_vm_area(tsk);
+
+ BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
+
+ if (vm) {
+ int i;
+
+ BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
+
+ for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
+ mod_zone_page_state(page_zone(vm->pages[i]),
+ NR_KERNEL_STACK_KB,
+ PAGE_SIZE / 1024 * account);
+ }
- mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
- THREAD_SIZE / 1024 * account);
+ /* All stack pages belong to the same memcg. */
+ memcg_kmem_update_page_stat(vm->pages[0], MEMCG_KERNEL_STACK_KB,
+ account * (THREAD_SIZE / 1024));
+ } else {
+ /*
+ * All stack pages are in the same zone and belong to the
+ * same memcg.
+ */
+ struct page *first_page = virt_to_page(stack);
+
+ mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
+ THREAD_SIZE / 1024 * account);
- memcg_kmem_update_page_stat(
- first_page, MEMCG_KERNEL_STACK_KB,
- account * (THREAD_SIZE / 1024));
+ memcg_kmem_update_page_stat(first_page, MEMCG_KERNEL_STACK_KB,
+ account * (THREAD_SIZE / 1024));
+ }
}
void free_task(struct task_struct *tsk)
{
- account_kernel_stack(tsk->stack, -1);
+ account_kernel_stack(tsk, -1);
arch_release_thread_stack(tsk->stack);
- free_thread_stack(tsk->stack);
+ free_thread_stack(tsk);
rt_mutex_debug_task_free(tsk);
ftrace_graph_exit_task(tsk);
put_seccomp_filter(tsk);
@@ -342,6 +385,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
{
struct task_struct *tsk;
unsigned long *stack;
+ struct vm_struct *stack_vm_area;
int err;
if (node == NUMA_NO_NODE)
@@ -354,11 +398,23 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
if (!stack)
goto free_tsk;
+ stack_vm_area = task_stack_vm_area(tsk);
+
err = arch_dup_task_struct(tsk, orig);
+
+ /*
+ * arch_dup_task_struct clobbers the stack-related fields. Make
+ * sure they're properly initialized before using any stack-related
+ * functions again.
+ */
+ tsk->stack = stack;
+#ifdef CONFIG_VMAP_STACK
+ tsk->stack_vm_area = stack_vm_area;
+#endif
+
if (err)
goto free_stack;
- tsk->stack = stack;
#ifdef CONFIG_SECCOMP
/*
* We must handle setting up seccomp filters once we're under
@@ -390,14 +446,14 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
tsk->task_frag.page = NULL;
tsk->wake_q.next = NULL;
- account_kernel_stack(stack, 1);
+ account_kernel_stack(tsk, 1);
kcov_task_init(tsk);
return tsk;
free_stack:
- free_thread_stack(stack);
+ free_thread_stack(tsk);
free_tsk:
free_task_struct(tsk);
return NULL;
--
2.7.4
next prev parent reply other threads:[~2016-07-11 20:54 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-11 20:53 [PATCH v5 00/32] virtually mapped stacks and thread_info cleanup Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 01/32] bluetooth: Switch SMP to crypto_cipher_encrypt_one() Andy Lutomirski
2016-07-14 19:10 ` Andy Lutomirski
2016-07-14 20:30 ` Marcel Holtmann
2016-07-14 20:41 ` David Miller
2016-07-11 20:53 ` [PATCH v5 02/32] x86/mm/hotplug: Don't remove PGD entries in remove_pagetable() Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 03/32] x86/cpa: In populate_pgd, don't set the pgd entry until it's populated Andy Lutomirski
2016-07-22 4:43 ` [kernel-hardening] " Valdis.Kletnieks
2016-07-22 5:34 ` Andy Lutomirski
2016-07-22 10:21 ` Ingo Molnar
2016-07-22 18:21 ` Andy Lutomirski
2016-07-22 18:31 ` Andy Lutomirski
2016-07-22 20:11 ` Ingo Molnar
2016-07-23 5:21 ` Valdis.Kletnieks
2016-07-23 14:58 ` Nicolai Stange
2016-07-28 9:26 ` Valdis.Kletnieks
2016-07-11 20:53 ` [PATCH v5 04/32] x86/mm: Remove kernel_unmap_pages_in_pgd() and efi_cleanup_page_tables() Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 05/32] mm: Track NR_KERNEL_STACK in KiB instead of number of stacks Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 06/32] mm: Fix memcg stack accounting for sub-page stacks Andy Lutomirski
2016-07-11 20:53 ` Andy Lutomirski [this message]
2016-07-11 20:53 ` [PATCH v5 08/32] dma-api: Teach the "DMA-from-stack" check about vmapped stacks Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 09/32] x86/dumpstack: When OOPSing, rewind the stack before do_exit() Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 10/32] x86/dumpstack: Honor supplied @regs arg Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 11/32] x86/dumpstack: Try harder to get a call trace on stack overflow Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 12/32] x86/dumpstack/64: Handle faults when printing the "Stack:" part of an OOPS Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 13/32] x86/mm/64: In vmalloc_fault(), use CR3 instead of current->active_mm Andy Lutomirski
2016-07-12 17:51 ` [kernel-hardening] " Dave Hansen
2016-07-12 18:03 ` Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 14/32] x86/mm/64: Enable vmapped stacks Andy Lutomirski
2016-07-13 7:53 ` Ingo Molnar
2016-07-13 18:42 ` Andy Lutomirski
2016-07-14 8:34 ` Ingo Molnar
2016-07-14 16:51 ` Andy Lutomirski
2016-07-14 18:45 ` Ingo Molnar
2016-07-11 20:53 ` [PATCH v5 15/32] x86/mm: Improve stack-overflow #PF handling Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 16/32] x86: Move uaccess_err and sig_on_uaccess_err to thread_struct Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 17/32] x86: Move addr_limit " Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 18/32] signal: Consolidate {TS,TLF}_RESTORE_SIGMASK code Andy Lutomirski
2016-07-12 11:57 ` Brian Gerst
2016-07-12 23:01 ` Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 19/32] x86/smp: Remove stack_smp_processor_id() Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 20/32] x86/smp: Remove unnecessary initialization of thread_info::cpu Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 21/32] x86/asm: Move 'status' from struct thread_info to struct thread_struct Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 22/32] kdb: Use task_cpu() instead of task_thread_info()->cpu Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 23/32] printk: When dumping regs, show the stack, not thread_info Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 24/32] x86/entry: Get rid of pt_regs_to_thread_info() Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 25/32] um: Stop conflating task_struct::stack with thread_info Andy Lutomirski
2016-07-11 20:53 ` [PATCH v5 26/32] sched: Allow putting thread_info into task_struct Andy Lutomirski
2016-07-11 20:54 ` [PATCH v5 27/32] x86: Move " Andy Lutomirski
2016-07-11 20:54 ` [PATCH v5 28/32] sched: Add try_get_task_stack() and put_task_stack() Andy Lutomirski
2016-07-11 20:54 ` [PATCH v5 29/32] kthread: to_live_kthread() needs try_get_task_stack() Andy Lutomirski
2016-07-11 20:54 ` [PATCH v5 30/32] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Andy Lutomirski
2016-07-11 20:54 ` [PATCH v5 31/32] sched: Free the stack early if CONFIG_THREAD_INFO_IN_TASK Andy Lutomirski
2016-07-11 20:54 ` [PATCH v5 32/32] fork: Cache two thread stacks per cpu if CONFIG_VMAP_STACK is set Andy Lutomirski
2016-07-12 8:56 ` [PATCH v5 00/32] virtually mapped stacks and thread_info cleanup Herbert Xu
2016-07-13 8:54 ` Christian Borntraeger
2016-07-13 18:36 ` Andy Lutomirski
2016-07-13 18:53 ` Christian Borntraeger
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=51f37059777910f989486657d1e27ded4c7edad2.1468270393.git.luto@kernel.org \
--to=luto@kernel.org \
--cc=bp@alien8.de \
--cc=brgerst@gmail.com \
--cc=heiko.carstens@de.ibm.com \
--cc=jann@thejh.net \
--cc=jpoimboe@redhat.com \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=nadav.amit@gmail.com \
--cc=oleg@redhat.com \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).