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Message-Id: <20221129191839.2471308-1-jannh@google.com>
Date: Tue, 29 Nov 2022 20:18:38 +0100
From: Jann Horn <jannh@...gle.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Andrei Vagin <avagin@...il.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] time/namespace: Refactor copy-pasted helper into one copy
find_timens_vvar_page() is not arch-specific, as can be seen from how all
five per-architecture versions of it are the same.
(arm64, powerpc and riscv are exactly the same; x86 and s390 have two
characters difference inside a comment, less blank lines, and mark the
!CONFIG_TIME_NS version as inline.)
Refactor the five copies into a central copy in kernel/time/namespace.c.
Marked for stable backporting because it is a prerequisite for the
following patch.
Cc: stable@...r.kernel.org
Signed-off-by: Jann Horn <jannh@...gle.com>
---
arch/arm64/kernel/vdso.c | 22 ----------------------
arch/powerpc/kernel/vdso.c | 22 ----------------------
arch/riscv/kernel/vdso.c | 22 ----------------------
arch/s390/kernel/vdso.c | 20 --------------------
arch/x86/entry/vdso/vma.c | 23 -----------------------
include/linux/time_namespace.h | 6 ++++++
kernel/time/namespace.c | 20 ++++++++++++++++++++
7 files changed, 26 insertions(+), 109 deletions(-)
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 99ae81ab91a74..e59a32aa0c49d 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -151,28 +151,6 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
mmap_read_unlock(mm);
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/$pid/mem or
- * process_vm_{readv,writev}() as long as there's no .access()
- * in special_mapping_vmops.
- * For more details check_vma_flags() and __access_remote_vm()
- */
- WARN(1, "vvar_page accessed remotely");
-
- return NULL;
-}
-#else
-static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
-{
- return NULL;
-}
#endif
static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 4abc019497020..507f8228f983b 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -129,28 +129,6 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
return 0;
}
-
-static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
-{
- if (likely(vma->vm_mm == current->mm))
- return current->nsproxy->time_ns->vvar_page;
-
- /*
- * VM_PFNMAP | VM_IO protect .fault() handler from being called
- * through interfaces like /proc/$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 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,
diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
index 123d05255fcfa..e410275918ac4 100644
--- a/arch/riscv/kernel/vdso.c
+++ b/arch/riscv/kernel/vdso.c
@@ -137,28 +137,6 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
mmap_read_unlock(mm);
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/$pid/mem or
- * process_vm_{readv,writev}() as long as there's no .access()
- * in special_mapping_vmops.
- * For more details check_vma_flags() and __access_remote_vm()
- */
- WARN(1, "vvar_page accessed remotely");
-
- return NULL;
-}
-#else
-static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
-{
- return NULL;
-}
#endif
static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
index 3105ca5bd4701..d6df7169c01f2 100644
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -44,21 +44,6 @@ struct vdso_data *arch_get_vdso_data(void *vvar_page)
return (struct vdso_data *)(vvar_page);
}
-static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
-{
- if (likely(vma->vm_mm == current->mm))
- return current->nsproxy->time_ns->vvar_page;
- /*
- * VM_PFNMAP | VM_IO protect .fault() handler from being called
- * through interfaces like /proc/$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;
-}
-
/*
* The VVAR page layout depends on whether a task belongs to the root or
* non-root time namespace. Whenever a task changes its namespace, the VVAR
@@ -84,11 +69,6 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
mmap_read_unlock(mm);
return 0;
}
-#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,
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 311eae30e0894..6b36485054e8a 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -98,24 +98,6 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
}
#ifdef CONFIG_TIME_NS
-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;
-}
-
/*
* The vvar page layout depends on whether a task belongs to the root or
* non-root time namespace. Whenever a task changes its namespace, the VVAR
@@ -140,11 +122,6 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
return 0;
}
-#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,
diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 3146f1c056c98..bb9d3f5542f8e 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -45,6 +45,7 @@ struct time_namespace *copy_time_ns(unsigned long flags,
void free_time_ns(struct time_namespace *ns);
void timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk);
struct vdso_data *arch_get_vdso_data(void *vvar_page);
+struct page *find_timens_vvar_page(struct vm_area_struct *vma);
static inline void put_time_ns(struct time_namespace *ns)
{
@@ -141,6 +142,11 @@ static inline void timens_on_fork(struct nsproxy *nsproxy,
return;
}
+static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)
+{
+ return NULL;
+}
+
static inline void timens_add_monotonic(struct timespec64 *ts) { }
static inline void timens_add_boottime(struct timespec64 *ts) { }
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index aec832801c26c..761c0ada5142a 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -192,6 +192,26 @@ static void timens_setup_vdso_data(struct vdso_data *vdata,
offset[CLOCK_BOOTTIME_ALARM] = boottime;
}
+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;
+}
+
+
+
/*
* Protects possibly multiple offsets writers racing each other
* and tasks entering the namespace.
base-commit: ca57f02295f188d6c65ec02202402979880fa6d8
--
2.38.1.584.g0f3c55d4c2-goog
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