In some situations the userspace memory context may live longer than
the userspace process itself so if we need to do proper memory context
cleanup, we better have tce_container take a reference to mm_struct and
use it later when the process is gone (@current or @current->mm is NULL).
This references mm and stores the pointer in the container; this is done
in a new helper - tce_iommu_mm_set() - when one of the following happens:
- a container is enabled (IOMMU v1);
- a first attempt to pre-register memory is made (IOMMU v2);
- a DMA window is created (IOMMU v2).
The @mm stays referenced till the container is destroyed.
This replaces current->mm with container->mm everywhere except debug
prints.
This adds a check that current->mm is the same as the one stored in
the container to prevent userspace from making changes to a memory
context of other processes.
DMA map/unmap ioctls() do not check for @mm as they already check
for @enabled which is set after tce_iommu_mm_set() is called.
Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
---
Changes:
v5:
* postpone referencing of mm
v4:
* added check for container->mm!=current->mm in tce_iommu_ioctl()
for all ioctls and removed other redundand checks
---
drivers/vfio/vfio_iommu_spapr_tce.c | 159 ++++++++++++++++++++++--------------
1 file changed, 99 insertions(+), 60 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 1c02498..9a81a7e 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -31,49 +31,49 @@
static void tce_iommu_detach_group(void *iommu_data,
struct iommu_group *iommu_group);
-static long try_increment_locked_vm(long npages)
+static long try_increment_locked_vm(struct mm_struct *mm, long npages)
{
long ret = 0, locked, lock_limit;
- if (!current || !current->mm)
- return -ESRCH; /* process exited */
+ if (!mm)
+ return -EPERM;
if (!npages)
return 0;
- down_write(¤t->mm->mmap_sem);
- locked = current->mm->locked_vm + npages;
+ down_write(&mm->mmap_sem);
+ locked = mm->locked_vm + npages;
lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
if (locked > lock_limit && !capable(CAP_IPC_LOCK))
ret = -ENOMEM;
else
- current->mm->locked_vm += npages;
+ mm->locked_vm += npages;
pr_debug("[%d] RLIMIT_MEMLOCK +%ld %ld/%ld%s\n", current->pid,
npages << PAGE_SHIFT,
- current->mm->locked_vm << PAGE_SHIFT,
+ mm->locked_vm << PAGE_SHIFT,
rlimit(RLIMIT_MEMLOCK),
ret ? " - exceeded" : "");
- up_write(¤t->mm->mmap_sem);
+ up_write(&mm->mmap_sem);
return ret;
}
-static void decrement_locked_vm(long npages)
+static void decrement_locked_vm(struct mm_struct *mm, long npages)
{
- if (!current || !current->mm || !npages)
- return; /* process exited */
+ if (!mm && !npages)
+ return;
- down_write(¤t->mm->mmap_sem);
- if (WARN_ON_ONCE(npages > current->mm->locked_vm))
- npages = current->mm->locked_vm;
- current->mm->locked_vm -= npages;
+ down_write(&mm->mmap_sem);
+ if (WARN_ON_ONCE(npages > mm->locked_vm))
+ npages = mm->locked_vm;
+ mm->locked_vm -= npages;
pr_debug("[%d] RLIMIT_MEMLOCK -%ld %ld/%ld\n", current->pid,
npages << PAGE_SHIFT,
- current->mm->locked_vm << PAGE_SHIFT,
+ mm->locked_vm << PAGE_SHIFT,
rlimit(RLIMIT_MEMLOCK));
- up_write(¤t->mm->mmap_sem);
+ up_write(&mm->mmap_sem);
}
/*
@@ -99,26 +99,38 @@ struct tce_container {
bool v2;
bool def_window_pending;
unsigned long locked_pages;
+ struct mm_struct *mm;
struct iommu_table *tables[IOMMU_TABLE_GROUP_MAX_TABLES];
struct list_head group_list;
};
+static long tce_iommu_mm_set(struct tce_container *container)
+{
+ if (container->mm) {
+ if (container->mm == current->mm)
+ return 0;
+ return -EPERM;
+ }
+ BUG_ON(!current->mm);
+ container->mm = current->mm;
+ atomic_inc(&container->mm->mm_count);
+
+ return 0;
+}
+
static long tce_iommu_unregister_pages(struct tce_container *container,
__u64 vaddr, __u64 size)
{
struct mm_iommu_table_group_mem_t *mem;
- if (!current || !current->mm)
- return -ESRCH; /* process exited */
-
if ((vaddr & ~PAGE_MASK) || (size & ~PAGE_MASK))
return -EINVAL;
- mem = mm_iommu_find(current->mm, vaddr, size >> PAGE_SHIFT);
+ mem = mm_iommu_find(container->mm, vaddr, size >> PAGE_SHIFT);
if (!mem)
return -ENOENT;
- return mm_iommu_put(current->mm, mem);
+ return mm_iommu_put(container->mm, mem);
}
static long tce_iommu_register_pages(struct tce_container *container,
@@ -128,14 +140,11 @@ static long tce_iommu_register_pages(struct tce_container *container,
struct mm_iommu_table_group_mem_t *mem = NULL;
unsigned long entries = size >> PAGE_SHIFT;
- if (!current || !current->mm)
- return -ESRCH; /* process exited */
-
if ((vaddr & ~PAGE_MASK) || (size & ~PAGE_MASK) ||
((vaddr + size) < vaddr))
return -EINVAL;
- ret = mm_iommu_get(current->mm, vaddr, entries, &mem);
+ ret = mm_iommu_get(container->mm, vaddr, entries, &mem);
if (ret)
return ret;
@@ -144,7 +153,8 @@ static long tce_iommu_register_pages(struct tce_container *container,
return 0;
}
-static long tce_iommu_userspace_view_alloc(struct iommu_table *tbl)
+static long tce_iommu_userspace_view_alloc(struct iommu_table *tbl,
+ struct mm_struct *mm)
{
unsigned long cb = _ALIGN_UP(sizeof(tbl->it_userspace[0]) *
tbl->it_size, PAGE_SIZE);
@@ -153,13 +163,13 @@ static long tce_iommu_userspace_view_alloc(struct iommu_table *tbl)
BUG_ON(tbl->it_userspace);
- ret = try_increment_locked_vm(cb >> PAGE_SHIFT);
+ ret = try_increment_locked_vm(mm, cb >> PAGE_SHIFT);
if (ret)
return ret;
uas = vzalloc(cb);
if (!uas) {
- decrement_locked_vm(cb >> PAGE_SHIFT);
+ decrement_locked_vm(mm, cb >> PAGE_SHIFT);
return -ENOMEM;
}
tbl->it_userspace = uas;
@@ -167,7 +177,8 @@ static long tce_iommu_userspace_view_alloc(struct iommu_table *tbl)
return 0;
}
-static void tce_iommu_userspace_view_free(struct iommu_table *tbl)
+static void tce_iommu_userspace_view_free(struct iommu_table *tbl,
+ struct mm_struct *mm)
{
unsigned long cb = _ALIGN_UP(sizeof(tbl->it_userspace[0]) *
tbl->it_size, PAGE_SIZE);
@@ -177,7 +188,7 @@ static void tce_iommu_userspace_view_free(struct iommu_table *tbl)
vfree(tbl->it_userspace);
tbl->it_userspace = NULL;
- decrement_locked_vm(cb >> PAGE_SHIFT);
+ decrement_locked_vm(mm, cb >> PAGE_SHIFT);
}
static bool tce_page_is_contained(struct page *page, unsigned page_shift)
@@ -237,9 +248,6 @@ static int tce_iommu_enable(struct tce_container *container)
struct iommu_table_group *table_group;
struct tce_iommu_group *tcegrp;
- if (!current->mm)
- return -ESRCH; /* process exited */
-
if (container->enabled)
return -EBUSY;
@@ -284,8 +292,12 @@ static int tce_iommu_enable(struct tce_container *container)
if (!table_group->tce32_size)
return -EPERM;
+ ret = tce_iommu_mm_set(container);
+ if (ret)
+ return ret;
+
locked = table_group->tce32_size >> PAGE_SHIFT;
- ret = try_increment_locked_vm(locked);
+ ret = try_increment_locked_vm(container->mm, locked);
if (ret)
return ret;
@@ -303,10 +315,8 @@ static void tce_iommu_disable(struct tce_container *container)
container->enabled = false;
- if (!current->mm)
- return;
-
- decrement_locked_vm(container->locked_pages);
+ BUG_ON(!container->mm);
+ decrement_locked_vm(container->mm, container->locked_pages);
}
static void *tce_iommu_open(unsigned long arg)
@@ -333,7 +343,8 @@ static void *tce_iommu_open(unsigned long arg)
static int tce_iommu_clear(struct tce_container *container,
struct iommu_table *tbl,
unsigned long entry, unsigned long pages);
-static void tce_iommu_free_table(struct iommu_table *tbl);
+static void tce_iommu_free_table(struct tce_container *container,
+ struct iommu_table *tbl);
static void tce_iommu_release(void *iommu_data)
{
@@ -358,10 +369,12 @@ static void tce_iommu_release(void *iommu_data)
continue;
tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
- tce_iommu_free_table(tbl);
+ tce_iommu_free_table(container, tbl);
}
tce_iommu_disable(container);
+ if (container->mm)
+ mmdrop(container->mm);
mutex_destroy(&container->lock);
kfree(container);
@@ -376,13 +389,14 @@ static void tce_iommu_unuse_page(struct tce_container *container,
put_page(page);
}
-static int tce_iommu_prereg_ua_to_hpa(unsigned long tce, unsigned long size,
+static int tce_iommu_prereg_ua_to_hpa(struct tce_container *container,
+ unsigned long tce, unsigned long size,
unsigned long *phpa, struct mm_iommu_table_group_mem_t **pmem)
{
long ret = 0;
struct mm_iommu_table_group_mem_t *mem;
- mem = mm_iommu_lookup(current->mm, tce, size);
+ mem = mm_iommu_lookup(container->mm, tce, size);
if (!mem)
return -EINVAL;
@@ -395,18 +409,18 @@ static int tce_iommu_prereg_ua_to_hpa(unsigned long tce, unsigned long size,
return 0;
}
-static void tce_iommu_unuse_page_v2(struct iommu_table *tbl,
- unsigned long entry)
+static void tce_iommu_unuse_page_v2(struct tce_container *container,
+ struct iommu_table *tbl, unsigned long entry)
{
struct mm_iommu_table_group_mem_t *mem = NULL;
int ret;
unsigned long hpa = 0;
unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
- if (!pua || !current || !current->mm)
+ if (!pua)
return;
- ret = tce_iommu_prereg_ua_to_hpa(*pua, IOMMU_PAGE_SIZE(tbl),
+ ret = tce_iommu_prereg_ua_to_hpa(container, *pua, IOMMU_PAGE_SIZE(tbl),
&hpa, &mem);
if (ret)
pr_debug("%s: tce %lx at #%lx was not cached, ret=%d\n",
@@ -436,7 +450,7 @@ static int tce_iommu_clear(struct tce_container *container,
continue;
if (container->v2) {
- tce_iommu_unuse_page_v2(tbl, entry);
+ tce_iommu_unuse_page_v2(container, tbl, entry);
continue;
}
@@ -517,7 +531,7 @@ static long tce_iommu_build_v2(struct tce_container *container,
enum dma_data_direction dirtmp;
if (!tbl->it_userspace) {
- ret = tce_iommu_userspace_view_alloc(tbl);
+ ret = tce_iommu_userspace_view_alloc(tbl, container->mm);
if (ret)
return ret;
}
@@ -527,8 +541,8 @@ static long tce_iommu_build_v2(struct tce_container *container,
unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl,
entry + i);
- ret = tce_iommu_prereg_ua_to_hpa(tce, IOMMU_PAGE_SIZE(tbl),
- &hpa, &mem);
+ ret = tce_iommu_prereg_ua_to_hpa(container,
+ tce, IOMMU_PAGE_SIZE(tbl), &hpa, &mem);
if (ret)
break;
@@ -549,7 +563,7 @@ static long tce_iommu_build_v2(struct tce_container *container,
ret = iommu_tce_xchg(tbl, entry + i, &hpa, &dirtmp);
if (ret) {
/* dirtmp cannot be DMA_NONE here */
- tce_iommu_unuse_page_v2(tbl, entry + i);
+ tce_iommu_unuse_page_v2(container, tbl, entry + i);
pr_err("iommu_tce: %s failed ioba=%lx, tce=%lx, ret=%ld\n",
__func__, entry << tbl->it_page_shift,
tce, ret);
@@ -557,7 +571,7 @@ static long tce_iommu_build_v2(struct tce_container *container,
}
if (dirtmp != DMA_NONE)
- tce_iommu_unuse_page_v2(tbl, entry + i);
+ tce_iommu_unuse_page_v2(container, tbl, entry + i);
*pua = tce;
@@ -585,7 +599,7 @@ static long tce_iommu_create_table(struct tce_container *container,
if (!table_size)
return -EINVAL;
- ret = try_increment_locked_vm(table_size >> PAGE_SHIFT);
+ ret = try_increment_locked_vm(container->mm, table_size >> PAGE_SHIFT);
if (ret)
return ret;
@@ -598,13 +612,14 @@ static long tce_iommu_create_table(struct tce_container *container,
return ret;
}
-static void tce_iommu_free_table(struct iommu_table *tbl)
+static void tce_iommu_free_table(struct tce_container *container,
+ struct iommu_table *tbl)
{
unsigned long pages = tbl->it_allocated_size >> PAGE_SHIFT;
- tce_iommu_userspace_view_free(tbl);
+ tce_iommu_userspace_view_free(tbl, container->mm);
tbl->it_ops->free(tbl);
- decrement_locked_vm(pages);
+ decrement_locked_vm(container->mm, pages);
}
static long tce_iommu_create_window(struct tce_container *container,
@@ -667,7 +682,7 @@ static long tce_iommu_create_window(struct tce_container *container,
table_group = iommu_group_get_iommudata(tcegrp->grp);
table_group->ops->unset_window(table_group, num);
}
- tce_iommu_free_table(tbl);
+ tce_iommu_free_table(container, tbl);
return ret;
}
@@ -705,7 +720,7 @@ static long tce_iommu_remove_window(struct tce_container *container,
/* Free table */
tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
- tce_iommu_free_table(tbl);
+ tce_iommu_free_table(container, tbl);
container->tables[num] = NULL;
return 0;
@@ -754,7 +769,17 @@ static long tce_iommu_ioctl(void *iommu_data,
}
return (ret < 0) ? 0 : ret;
+ }
+ /*
+ * Sanity check to prevent one userspace from manipulating
+ * another userspace mm.
+ */
+ BUG_ON(!container);
+ if (container->mm && container->mm != current->mm)
+ return -EPERM;
+
+ switch (cmd) {
case VFIO_IOMMU_SPAPR_TCE_GET_INFO: {
struct vfio_iommu_spapr_tce_info info;
struct tce_iommu_group *tcegrp;
@@ -929,6 +954,10 @@ static long tce_iommu_ioctl(void *iommu_data,
minsz = offsetofend(struct vfio_iommu_spapr_register_memory,
size);
+ ret = tce_iommu_mm_set(container);
+ if (ret)
+ return ret;
+
if (copy_from_user(¶m, (void __user *)arg, minsz))
return -EFAULT;
@@ -952,6 +981,9 @@ static long tce_iommu_ioctl(void *iommu_data,
if (!container->v2)
break;
+ if (!container->mm)
+ return -EPERM;
+
minsz = offsetofend(struct vfio_iommu_spapr_register_memory,
size);
@@ -1010,6 +1042,10 @@ static long tce_iommu_ioctl(void *iommu_data,
if (!container->v2)
break;
+ ret = tce_iommu_mm_set(container);
+ if (ret)
+ return ret;
+
if (!tce_groups_attached(container))
return -ENXIO;
@@ -1046,6 +1082,9 @@ static long tce_iommu_ioctl(void *iommu_data,
if (!container->v2)
break;
+ if (!container->mm)
+ return -EPERM;
+
if (!tce_groups_attached(container))
return -ENXIO;
@@ -1092,7 +1131,7 @@ static void tce_iommu_release_ownership(struct tce_container *container,
continue;
tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
- tce_iommu_userspace_view_free(tbl);
+ tce_iommu_userspace_view_free(tbl, container->mm);
if (tbl->it_map)
iommu_release_ownership(tbl);
--
2.5.0.rc3
--
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