From: Andrei Vagin <avagin@gmail.com>
To: Vincenzo Frascino <vincenzo.frascino@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Mark Rutland <mark.rutland@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andrei Vagin <avagin@gmail.com>, Dmitry Safonov <dima@arista.com>
Subject: [PATCH 4/6] arm64/vdso: Handle faults on timens page
Date: Wed, 15 Apr 2020 22:26:16 -0700 [thread overview]
Message-ID: <20200416052618.804515-5-avagin@gmail.com> (raw)
In-Reply-To: <20200416052618.804515-1-avagin@gmail.com>
If a task belongs to a time namespace then the VVAR page which contains
the system wide VDSO data is replaced with a namespace specific page
which has the same layout as the VVAR page.
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
---
arch/arm64/kernel/vdso.c | 57 +++++++++++++++++++++++++++++++++++++---
1 file changed, 53 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index b3e7ce24e59b..fb32c6f76078 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -18,6 +18,7 @@
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/slab.h>
+#include <linux/time_namespace.h>
#include <linux/timekeeper_internal.h>
#include <linux/vmalloc.h>
#include <vdso/datapage.h>
@@ -175,15 +176,63 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
up_write(&mm->mmap_sem);
return 0;
}
+
+static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
+{
+ if (likely(vma->vm_mm == current->mm))
+ return current->nsproxy->time_ns->vvar_page;
+
+ /*
+ * VM_PFNMAP | VM_IO protect .fault() handler from being called
+ * through interfaces like /proc/$pid/mem or
+ * process_vm_{readv,writev}() as long as there's no .access()
+ * in special_mapping_vmops().
+ * For more details check_vma_flags() and __access_remote_vm()
+ */
+
+ WARN(1, "vvar_page accessed remotely");
+
+ return NULL;
+}
+#else
+static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)
+{
+ return NULL;
+}
#endif
static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
struct vm_area_struct *vma, struct vm_fault *vmf)
{
- if (vmf->pgoff == 0)
- return vmf_insert_pfn(vma, vmf->address,
- sym_to_pfn(vdso_data));
- return VM_FAULT_SIGBUS;
+ struct page *timens_page = find_timens_vvar_page(vma);
+ unsigned long pfn;
+
+ switch (vmf->pgoff) {
+ case VVAR_DATA_PAGE_OFFSET:
+ if (timens_page)
+ pfn = page_to_pfn(timens_page);
+ else
+ pfn = sym_to_pfn(vdso_data);
+ break;
+#ifdef CONFIG_TIME_NS
+ case VVAR_TIMENS_PAGE_OFFSET:
+ /*
+ * If a task belongs to a time namespace then a namespace
+ * specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and
+ * the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET
+ * offset.
+ * See also the comment near timens_setup_vdso_data().
+ */
+ if (!timens_page)
+ return VM_FAULT_SIGBUS;
+ pfn = sym_to_pfn(vdso_data);
+ break;
+#endif /* CONFIG_TIME_NS */
+ default:
+ return VM_FAULT_SIGBUS;
+ }
+
+ return vmf_insert_pfn(vma, vmf->address, pfn);
}
static int __setup_additional_pages(enum arch_vdso_type arch_index,
--
2.24.1
next prev parent reply other threads:[~2020-04-16 5:27 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-16 5:26 [PATCH v3 0/6] arm64: add the time namespace support Andrei Vagin
2020-04-16 5:26 ` [PATCH 1/6] arm64/vdso: use the fault callback to map vvar pages Andrei Vagin
2020-04-16 5:26 ` [PATCH 2/6] arm64/vdso: Zap vvar pages when switching to a time namespace Andrei Vagin
2020-04-16 5:26 ` [PATCH 3/6] arm64/vdso: Add time napespace page Andrei Vagin
2020-04-16 10:45 ` Mark Rutland
2020-04-23 5:23 ` Andrei Vagin
2020-04-17 4:11 ` [PATCH 3/6 v2] arm64/vdso: Add time namespace page Andrei Vagin
2020-04-16 5:26 ` Andrei Vagin [this message]
2020-04-16 5:26 ` [PATCH 5/6] arm64/vdso: Restrict splitting VVAR VMA Andrei Vagin
2020-04-16 5:26 ` [PATCH 6/6] arm64: enable time namespace support Andrei Vagin
2020-05-20 12:02 ` [PATCH v3 0/6] arm64: add the " Vincenzo Frascino
2020-06-02 18:02 [PATCH RESEND " Andrei Vagin
2020-06-02 18:02 ` [PATCH 4/6] arm64/vdso: Handle faults on timens page Andrei Vagin
2020-06-16 7:55 [PATCH v4 0/6] arm64: add the time namespace support Andrei Vagin
2020-06-16 7:55 ` [PATCH 4/6] arm64/vdso: Handle faults on timens page Andrei Vagin
2020-06-24 8:33 [PATCH v5 0/6] arm64: add the time namespace support Andrei Vagin
2020-06-24 8:33 ` [PATCH 4/6] arm64/vdso: Handle faults on timens page Andrei Vagin
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=20200416052618.804515-5-avagin@gmail.com \
--to=avagin@gmail.com \
--cc=catalin.marinas@arm.com \
--cc=dima@arista.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=tglx@linutronix.de \
--cc=vincenzo.frascino@arm.com \
--cc=will@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).