VAS segments are an extension to first class virtual address spaces that
can be used to share specific memory regions between multiple first class
virtual address spaces. VAS segments have a specific size and position in a
virtual address space and can thereby be used to share in-memory pointer
based data structures between multiple address spaces as well as other
in-memory data without the need to represent them in mmap-able files or
use shmem.
Similar to first class virtual address spaces, VAS segments must be created
and destroyed explicitly by a user. The system will never automatically
destroy or create a virtual segment. Via attaching a VAS segment to a first
class virtual address space, the memory that is contained in the VAS
segment can be accessed and changed.
Signed-off-by: Till Smejkal <till.smejkal@xxxxxxxxx>
Signed-off-by: Marco Benatto <marco.antonio.780@xxxxxxxxx>
---
arch/x86/entry/syscalls/syscall_32.tbl | 7 +
arch/x86/entry/syscalls/syscall_64.tbl | 7 +
include/linux/syscalls.h | 10 +
include/linux/vas.h | 114 +++
include/linux/vas_types.h | 91 ++-
include/uapi/asm-generic/unistd.h | 16 +-
include/uapi/linux/vas.h | 12 +
kernel/sys_ni.c | 7 +
mm/vas.c | 1234 ++++++++++++++++++++++++++++++--
9 files changed, 1451 insertions(+), 47 deletions(-)
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 8c553eef8c44..a4f91d14a856 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -398,3 +398,10 @@
389 i386 active_vas sys_active_vas
390 i386 vas_getattr sys_vas_getattr
391 i386 vas_setattr sys_vas_setattr
+392 i386 vas_seg_create sys_vas_seg_create
+393 i386 vas_seg_delete sys_vas_seg_delete
+394 i386 vas_seg_find sys_vas_seg_find
+395 i386 vas_seg_attach sys_vas_seg_attach
+396 i386 vas_seg_detach sys_vas_seg_detach
+397 i386 vas_seg_getattr sys_vas_seg_getattr
+398 i386 vas_seg_setattr sys_vas_seg_setattr
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 72f1f0495710..a0f9503c3d28 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -347,6 +347,13 @@
338 common active_vas sys_active_vas
339 common vas_getattr sys_vas_getattr
340 common vas_setattr sys_vas_setattr
+341 common vas_seg_create sys_vas_seg_create
+342 common vas_seg_delete sys_vas_seg_delete
+343 common vas_seg_find sys_vas_seg_find
+344 common vas_seg_attach sys_vas_seg_attach
+345 common vas_seg_detach sys_vas_seg_detach
+346 common vas_seg_getattr sys_vas_seg_getattr
+347 common vas_seg_setattr sys_vas_seg_setattr
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index fdea27d37c96..7380dcdc4bc1 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -66,6 +66,7 @@ struct perf_event_attr;
struct file_handle;
struct sigaltstack;
struct vas_attr;
+struct vas_seg_attr;
union bpf_attr;
#include <linux/types.h>
@@ -914,4 +915,13 @@ asmlinkage long sys_active_vas(void);
asmlinkage long sys_vas_getattr(int vid, struct vas_attr __user *attr);
asmlinkage long sys_vas_setattr(int vid, struct vas_attr __user *attr);
+asmlinkage long sys_vas_seg_create(const char __user *name, unsigned long start,
+ unsigned long end, umode_t mode);
+asmlinkage long sys_vas_seg_delete(int sid);
+asmlinkage long sys_vas_seg_find(const char __user *name);
+asmlinkage long sys_vas_seg_attach(int vid, int sid, int type);
+asmlinkage long sys_vas_seg_detach(int vid, int sid);
+asmlinkage long sys_vas_seg_getattr(int sid, struct vas_seg_attr __user *attr);
+asmlinkage long sys_vas_seg_setattr(int sid, struct vas_seg_attr __user *attr);
+
#endif
diff --git a/include/linux/vas.h b/include/linux/vas.h
index 6a72e42f96d2..376b9fa1ee27 100644
--- a/include/linux/vas.h
+++ b/include/linux/vas.h
@@ -138,6 +138,120 @@ extern int vas_setattr(int vid, struct vas_attr *attr);
/***
+ * Management of VAS segments
+ ***/
+
+/**
+ * Lock and unlock helper for VAS segments.
+ **/
+#define vas_seg_lock(seg) mutex_lock(&(seg)->mtx)
+#define vas_seg_unlock(seg) mutex_unlock(&(seg)->mtx)
+
+/**
+ * Create a new VAS segment.
+ *
+ * @param[in] name: The name of the new VAS segment.
+ * @param[in] start: The address where the VAS segment begins.
+ * @param[in] end: The address where the VAS segment ends.
+ * @param[in] mode: The access rights for the VAS segment.
+ *
+ * @returns: The VAS segment ID on success, -ERRNO otherwise.
+ **/
+extern int vas_seg_create(const char *name, unsigned long start,
+ unsigned long end, umode_t mode);
+
+/**
+ * Get a pointer to a VAS segment data structure.
+ *
+ * @param[in] sid: The ID of the VAS segment whose data structure
+ * should be returned.
+ *
+ * @returns: The pointer to the VAS segment data structure
+ * on success, or NULL otherwise.
+ **/
+extern struct vas_seg *vas_seg_get(int sid);
+
+/**
+ * Return a pointer to a VAS segment data structure again.
+ *
+ * @param[in] seg: The pointer to the VAS segment data structure
+ * that should be returned.
+ **/
+extern void vas_seg_put(struct vas_seg *seg);
+
+/**
+ * Get ID of the VAS segment belonging to a given name.
+ *
+ * @param[in] name: The name of the VAS segment for which the ID
+ * should be returned.
+ *
+ * @returns: The VAS segment ID on success, -ERRNO
+ * otherwise.
+ **/
+extern int vas_seg_find(const char *name);
+
+/**
+ * Delete the given VAS segment again.
+ *
+ * @param[in] id: The ID of the VAS segment which should be
+ * deleted.
+ *
+ * @returns: 0 on success, -ERRNO otherwise.
+ **/
+extern int vas_seg_delete(int id);
+
+/**
+ * Attach a VAS segment to a VAS.
+ *
+ * @param[in] vid: The ID of the VAS to which the VAS segment
+ * should be attached.
+ * @param[in] sid: The ID of the VAS segment which should be
+ * attached.
+ * @param[in] type: The type how the VAS segment should be
+ * attached.
+ *
+ * @returns: 0 on success, -ERRNO otherwise.
+ **/
+extern int vas_seg_attach(int vid, int sid, int type);
+
+/**
+ * Detach a VAS segment from a VAS.
+ *
+ * @param[in] vid: The ID of the VAS from which the VAS segment
+ * should be detached.
+ * @param[in] sid: The ID of the VAS segment which should be
+ * detached.
+ *
+ * @returns: 0 on success, -ERRNO otherwise.
+ **/
+extern int vas_seg_detach(int vid, int sid);
+
+/**
+ * Get attributes of a VAS segment.
+ *
+ * @param[in] sid: The ID of the VAS segment for which the
+ * attributes should be returned.
+ * @param[out] attr: The pointer to the struct where the attributes
+ * should be saved.
+ *
+ * @returns: 0 on success, -ERRNO otherwise.
+ **/
+extern int vas_seg_getattr(int sid, struct vas_seg_attr *attr);
+
+/**
+ * Set attributes of a VAS segment.
+ *
+ * @param[in] sid: The ID of the VAS segment for which the
+ * attributes should be updated.
+ * @param[in] attr: The pointer to the struct containing the new
+ * attributes.
+ *
+ * @returns: 0 on success, -ERRNO otherwise.
+ **/
+extern int vas_seg_setattr(int sid, struct vas_seg_attr *attr);
+
+
+/***
* Management of the VAS subsystem
***/
diff --git a/include/linux/vas_types.h b/include/linux/vas_types.h
index f06bfa9ef729..a5291a18ea07 100644
--- a/include/linux/vas_types.h
+++ b/include/linux/vas_types.h
@@ -24,8 +24,8 @@ struct task_struct;
* The struct representing a Virtual Address Space (VAS).
*
* This data structure contains all the necessary information of a VAS such as
- * its name, ID. It also contains access rights and other management
- * information.
+ * its name, ID, as well as the list of all the VAS segments which are attached
+ * to it. It also contains access rights and other management information.
**/
struct vas {
struct kobject kobj; /* < the internal kobject that we use *
@@ -38,7 +38,8 @@ struct vas {
struct mutex mtx; /* < lock for parallel access. */
struct mm_struct *mm; /* < a partial memory map containing *
- * all mappings of this VAS. */
+ * all mappings of this VAS and all *
+ * of its attached VAS segments. */
struct list_head link; /* < the link in the global VAS list. */
struct rcu_head rcu; /* < the RCU helper used for *
@@ -54,6 +55,11 @@ struct vas {
* of the current sharing state of *
* the VAS. */
+ struct list_head segments; /* < the list of attached VAS *
+ * segments. */
+ u32 nr_segments; /* < the number of VAS segments *
+ * attached to this VAS. */
+
umode_t mode; /* < the access rights to this VAS. */
kuid_t uid; /* < the UID of the owning user of *
* this VAS. */
@@ -85,4 +91,83 @@ struct att_vas {
int type; /* < the type of attaching (RO/RW). */
};
+/**
+ * The struct representing a VAS segment.
+ *
+ * A VAS segment is a region in memory. Accordingly, it is very similar to a
+ * vm_area. However, instead of a vm_area it can only represent a memory region
+ * and not a file and also knows where it is mapped. In addition VAS segments
+ * also have an ID, a name, access rights and a lock managing the way it can be
+ * shared between multiple VAS.
+ **/
+struct vas_seg {
+ struct kobject kobj; /* < the internal kobject that we use *
+ * for reference counting and sysfs *
+ * handling. */
+
+ int id; /* < ID */
+ char name[VAS_MAX_NAME_LENGTH]; /* < name */
+
+ struct mutex mtx; /* < lock for parallel access. */
+
+ unsigned long start; /* < the virtual address where the *
+ * VAS segment starts. */
+ unsigned long end; /* < the virtual address where the *
+ * VAS segment ends. */
+ unsigned long length; /* < the size of the VAS segment in *
+ * bytes. */
+
+ struct mm_struct *mm; /* < a partial memory map containing *
+ * all the mappings for this VAS *
+ * segment. */
+
+ struct list_head link; /* < the link in the global VAS *
+ * segment list. */
+ struct rcu_head rcu; /* < the RCU helper used for *
+ * asynchronous VAS segment *
+ * deletion. */
+
+ u16 refcount; /* < how often is the VAS segment *
+ * attached. */
+ struct list_head attaches; /* < the list of VASes which have *
+ * this VAS segment attached. */
+
+ spinlock_t share_lock; /* < lock for protecting sharing *
+ * state. */
+ u32 sharing; /* < the variable used to keep track *
+ * of the current sharing state of *
+ * the VAS segment. */
+
+ umode_t mode; /* < the access rights to this VAS *
+ * segment. */
+ kuid_t uid; /* < the UID of the owning user of *
+ * this VAS segment. */
+ kgid_t gid; /* < the GID of the owning group of *
+ * this VAS segment. */
+};
+
+/**
+ * The struct representing a VAS segment being attached to a VAS.
+ *
+ * Since a VAS segment can be attached to a multiple VAS this data structure is
+ * necessary. It forms the connection between the VAS and the VAS segment
+ * itself.
+ **/
+struct att_vas_seg {
+ struct vas_seg *seg; /* < the reference to the actual VAS *
+ * segment containing all the *
+ * information. */
+
+ struct vas *vas; /* < the reference to the VAS to *
+ * which the VAS segment is *
+ * attached to. */
+
+ struct list_head vas_link; /* < the link in the list managed *
+ * inside the VAS. */
+ struct list_head seg_link; /* < the link in the list managed *
+ * inside the VAS segment. */
+
+ int type; /* < the type of attaching (RO/RW). */
+};
+
#endif
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 35df7d40a443..4014b4bd2f18 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -748,9 +748,23 @@ __SYSCALL(__NR_active_vas, sys_active_vas)
__SYSCALL(__NR_vas_getattr, sys_vas_getattr)
#define __NR_vas_setattr 299
__SYSCALL(__NR_vas_setattr, sys_vas_setattr)
+#define __NR_vas_seg_create 300
+__SYSCALL(__NR_vas_seg_create, sys_vas_seg_create)
+#define __NR_vas_seg_delete 301
+__SYSCALL(__NR_vas_seg_delete, sys_vas_seg_delete)
+#define __NR_vas_seg_find 302
+__SYSCALL(__NR_vas_seg_find, sys_vas_seg_find)
+#define __NR_vas_seg_attach 303
+__SYSCALL(__NR_vas_seg_attach, sys_vas_seg_attach)
+#define __NR_vas_seg_detach 304
+__SYSCALL(__NR_vas_seg_detach, sys_vas_seg_detach)
+#define __NR_vas_seg_getattr 305
+__SYSCALL(__NR_vas_seg_getattr, sys_vas_seg_getattr)
+#define __NR_vas_seg_setattr 306
+__SYSCALL(__NR_vas_seg_setattr, sys_vas_seg_setattr)
#undef __NR_syscalls
-#define __NR_syscalls 300
+#define __NR_syscalls 307
/*
* All syscalls below here should go away really,
diff --git a/include/uapi/linux/vas.h b/include/uapi/linux/vas.h
index 02f70f88bdcb..a8858b013a44 100644
--- a/include/uapi/linux/vas.h
+++ b/include/uapi/linux/vas.h
@@ -13,4 +13,16 @@ struct vas_attr {
__kernel_gid_t group; /* < the owning group of the VAS. */
};
+/**
+ * The struct containing attributes of a VAS segment.
+ **/
+struct vas_seg_attr {
+ __kernel_mode_t mode; /* < the access rights to the VAS *
+ * segment. */
+ __kernel_uid_t user; /* < the owning user of the VAS *
+ * segment. */
+ __kernel_gid_t group; /* < the owning group of the VAS *
+ * segment. */
+};
+
#endif
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index f6f83c5ec1a1..659fe96afcfa 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -269,3 +269,10 @@ cond_syscall(sys_vas_switch);
cond_syscall(sys_active_vas);
cond_syscall(sys_vas_getattr);
cond_syscall(sys_vas_setattr);
+cond_syscall(sys_segment_create);
+cond_syscall(sys_segment_delete);
+cond_syscall(sys_segment_find);
+cond_syscall(sys_segment_attach);
+cond_syscall(sys_segment_detach);
+cond_syscall(sys_segment_getattr);
+cond_syscall(sys_segment_setattr);
diff --git a/mm/vas.c b/mm/vas.c
index 447d61e1da79..345b023c21aa 100644
--- a/mm/vas.c
+++ b/mm/vas.c
@@ -61,7 +61,7 @@
#define VAS_MAX_ID INT_MAX
/**
- * Masks and bits to implement sharing of VAS.
+ * Masks and bits to implement sharing of VAS and VAS segments.
**/
#define VAS_SHARE_READABLE (1 << 0)
#define VAS_SHARE_WRITABLE (1 << 16)
@@ -194,6 +194,8 @@ static void __dump_memory_map(const char *title, struct mm_struct *mm)
static struct kmem_cache *vas_cachep;
static struct kmem_cache *att_vas_cachep;
static struct kmem_cache *vas_context_cachep;
+static struct kmem_cache *seg_cachep;
+static struct kmem_cache *att_seg_cachep;
/**
* Global management data structures and their associated locks.
@@ -201,16 +203,21 @@ static struct kmem_cache *vas_context_cachep;
static struct idr vases;
static spinlock_t vases_lock;
+static struct idr vas_segs;
+static spinlock_t vas_segs_lock;
+
/**
* The place holder variables that are used to identify to-be-deleted items in
* our global management data structures.
**/
static struct vas *INVALID_VAS;
+static struct vas_seg *INVALID_VAS_SEG;
/**
* Kernel 'ksets' where all objects will be managed.
**/
static struct kset *vases_kset;
+static struct kset *vas_segs_kset;
/***
@@ -273,6 +280,40 @@ static inline void __delete_vas_context(struct vas_context *ctx)
kmem_cache_free(vas_context_cachep, ctx);
}
+static inline struct vas_seg *__new_vas_seg(void)
+{
+ return kmem_cache_zalloc(seg_cachep, GFP_KERNEL);
+}
+
+static inline void __delete_vas_seg(struct vas_seg *seg)
+{
+ WARN_ON(seg->refcount != 0);
+
+ mutex_destroy(&seg->mtx);
+
+ if (seg->mm)
+ mmput_async(seg->mm);
+ kmem_cache_free(seg_cachep, seg);
+}
+
+static inline void __delete_vas_seg_rcu(struct rcu_head *rp)
+{
+ struct vas_seg *seg = container_of(rp, struct vas_seg, rcu);
+
+ __delete_vas_seg(seg);
+}
+
+static inline struct att_vas_seg *__new_att_vas_seg(void)
+{
+ return kmem_cache_zalloc(att_seg_cachep, GFP_ATOMIC);
+}
+
+static inline void __delete_att_vas_seg(struct att_vas_seg *aseg)
+{
+ kmem_cache_free(att_seg_cachep, aseg);
+}
+
+
/***
* Kobject management of data structures
***/
@@ -418,6 +459,161 @@ static struct kobj_type vas_ktype = {
.default_attrs = vas_default_attr,
};
+/**
+ * Correctly get and put VAS segments.
+ **/
+static inline struct vas_seg *__vas_seg_get(struct vas_seg *seg)
+{
+ return container_of(kobject_get(&seg->kobj), struct vas_seg, kobj);
+}
+
+static inline void __vas_seg_put(struct vas_seg *seg)
+{
+ kobject_put(&seg->kobj);
+}
+
+/**
+ * The sysfs structure we need to handle attributes of a VAS segment.
+ **/
+struct vas_seg_sysfs_attr {
+ struct attribute attr;
+ ssize_t (*show)(struct vas_seg *seg, struct vas_seg_sysfs_attr *ssattr,
+ char *buf);
+ ssize_t (*store)(struct vas_seg *seg, struct vas_seg_sysfs_attr *ssattr,
+ const char *buf, ssize_t count);
+};
+
+#define VAS_SEG_SYSFS_ATTR(NAME, MODE, SHOW, STORE) \
+static struct vas_seg_sysfs_attr vas_seg_sysfs_attr_##NAME = \
+ __ATTR(NAME, MODE, SHOW, STORE)
+
+/**
+ * Functions for all the sysfs operations for VAS segments.
+ **/
+static ssize_t __vas_seg_sysfs_attr_show(struct kobject *kobj,
+ struct attribute *attr,
+ char *buf)
+{
+ struct vas_seg *seg;
+ struct vas_seg_sysfs_attr *ssattr;
+
+ seg = container_of(kobj, struct vas_seg, kobj);
+ ssattr = container_of(attr, struct vas_seg_sysfs_attr, attr);
+
+ if (!ssattr->show)
+ return -EIO;
+
+ return ssattr->show(seg, ssattr, buf);
+}
+
+static ssize_t __vas_seg_sysfs_attr_store(struct kobject *kobj,
+ struct attribute *attr,
+ const char *buf, size_t count)
+{
+ struct vas_seg *seg;
+ struct vas_seg_sysfs_attr *ssattr;
+
+ seg = container_of(kobj, struct vas_seg, kobj);
+ ssattr = container_of(attr, struct vas_seg_sysfs_attr, attr);
+
+ if (!ssattr->store)
+ return -EIO;
+
+ return ssattr->store(seg, ssattr, buf, count);
+}
+
+/**
+ * The sysfs operations structure for a VAS segment.
+ **/
+static const struct sysfs_ops vas_seg_sysfs_ops = {
+ .show = __vas_seg_sysfs_attr_show,
+ .store = __vas_seg_sysfs_attr_store,
+};
+
+/**
+ * Default attributes of a VAS segment.
+ **/
+static ssize_t __show_vas_seg_name(struct vas_seg *seg,
+ struct vas_seg_sysfs_attr *ssattr,
+ char *buf)
+{
+ return scnprintf(buf, PAGE_SIZE, "%s", seg->name);
+}
+VAS_SEG_SYSFS_ATTR(name, 0444, __show_vas_seg_name, NULL);
+
+static ssize_t __show_vas_seg_mode(struct vas_seg *seg,
+ struct vas_seg_sysfs_attr *ssattr,
+ char *buf)
+{
+ return scnprintf(buf, PAGE_SIZE, "%#03o", seg->mode);
+}
+VAS_SEG_SYSFS_ATTR(mode, 0444, __show_vas_seg_mode, NULL);
+
+static ssize_t __show_vas_seg_user(struct vas_seg *seg,
+ struct vas_seg_sysfs_attr *ssattr,
+ char *buf)
+{
+ struct user_namespace *ns = current_user_ns();
+
+ return scnprintf(buf, PAGE_SIZE, "%d", from_kuid(ns, seg->uid));
+}
+VAS_SEG_SYSFS_ATTR(user, 0444, __show_vas_seg_user, NULL);
+
+static ssize_t __show_vas_seg_group(struct vas_seg *seg,
+ struct vas_seg_sysfs_attr *ssattr,
+ char *buf)
+{
+ struct user_namespace *ns = current_user_ns();
+
+ return scnprintf(buf, PAGE_SIZE, "%d", from_kgid(ns, seg->gid));
+}
+VAS_SEG_SYSFS_ATTR(group, 0444, __show_vas_seg_group, NULL);
+
+static ssize_t __show_vas_seg_region(struct vas_seg *seg,
+ struct vas_seg_sysfs_attr *ssattr,
+ char *buf)
+{
+ return scnprintf(buf, PAGE_SIZE, "%lx-%lx", seg->start, seg->end);
+}
+VAS_SEG_SYSFS_ATTR(region, 0444, __show_vas_seg_region, NULL);
+
+static struct attribute *vas_seg_default_attr[] = {
+ &vas_seg_sysfs_attr_name.attr,
+ &vas_seg_sysfs_attr_mode.attr,
+ &vas_seg_sysfs_attr_user.attr,
+ &vas_seg_sysfs_attr_group.attr,
+ &vas_seg_sysfs_attr_region.attr,
+ NULL
+};
+
+/**
+ * Function to release the VAS segment after its kobject is gone.
+ **/
+static void __vas_seg_release(struct kobject *kobj)
+{
+ struct vas_seg *seg = container_of(kobj, struct vas_seg, kobj);
+
+ /* Give up the ID in the IDR that was occupied by this VAS segment. */
+ spin_lock(&vas_segs_lock);
+ idr_remove(&vas_segs, seg->id);
+ spin_unlock(&vas_segs_lock);
+
+ /*
+ * Wait a full RCU grace period before actually deleting the VAS segment
+ * data structure since we haven't done it earlier.
+ */
+ call_rcu(&seg->rcu, __delete_vas_seg_rcu);
+}
+
+/**
+ * The ktype data structure representing a VAS segment.
+ **/
+static struct kobj_type vas_seg_ktype = {
+ .sysfs_ops = &vas_seg_sysfs_ops,
+ .release = __vas_seg_release,
+ .default_attrs = vas_seg_default_attr,
+};
+
/***
* Internally visible functions
@@ -526,8 +722,99 @@ static inline struct vas *vas_lookup_by_name(const char *name)
return vas;
}
+/**
+ * Working with the global VAS segments list.
+ **/
+static inline void vas_seg_remove(struct vas_seg *seg)
+{
+ spin_lock(&vas_segs_lock);
+
+ /*
+ * We only put a to-be-deleted place holder in the IDR at this point.
+ * See @vas_remove for more details.
+ */
+ idr_replace(&vas_segs, INVALID_VAS_SEG, seg->id);
+ spin_unlock(&vas_segs_lock);
+
+ /* No need to wait for grace period. See @vas_remove why. */
+ __vas_seg_put(seg);
+}
+
+static inline int vas_seg_insert(struct vas_seg *seg)
+{
+ int ret;
+
+ /* Add the VAS segment in the IDR cache. */
+ spin_lock(&vas_segs_lock);
+
+ ret = idr_alloc(&vas_segs, seg, 1, VAS_MAX_ID, GFP_KERNEL);
+
+ spin_unlock(&vas_segs_lock);
+
+ if (ret < 0) {
+ __delete_vas_seg(seg);
+ return ret;
+ }
+
+ /* Add the remaining data to the VAS segment's data structure. */
+ seg->id = ret;
+ seg->kobj.kset = vas_segs_kset;
+
+ /* Initialize the kobject and add it to the sysfs. */
+ ret = kobject_init_and_add(&seg->kobj, &vas_seg_ktype, NULL,
+ "%d", seg->id);
+ if (ret != 0) {
+ vas_seg_remove(seg);
+ return ret;
+ }
+
+ kobject_uevent(&seg->kobj, KOBJ_ADD);
+
+ return 0;
+}
+
+static inline struct vas_seg *vas_seg_lookup(int id)
+{
+ struct vas_seg *seg;
+
+ rcu_read_lock();
+
+ seg = idr_find(&vas_segs, id);
+ if (seg == INVALID_VAS_SEG)
+ seg = NULL;
+ if (seg)
+ seg = __vas_seg_get(seg);
+
+ rcu_read_unlock();
+
+ return seg;
+}
+
+static inline struct vas_seg *vas_seg_lookup_by_name(const char *name)
+{
+ struct vas_seg *seg;
+ int id;
+
+ rcu_read_lock();
+
+ idr_for_each_entry(&vas_segs, seg, id) {
+ if (seg == INVALID_VAS_SEG)
+ continue;
+
+ if (strcmp(seg->name, name) == 0)
+ break;
+ }
+
+ if (seg)
+ seg = __vas_seg_get(seg);
+
+ rcu_read_unlock();
+
+ return seg;
+}
+
/**
- * Management of the sharing of VAS.
+ * Management of the sharing of VAS and VAS segments.
**/
static inline int vas_take_share(int type, struct vas *vas)
{
@@ -562,6 +849,39 @@ static inline void vas_put_share(int type, struct vas *vas)
spin_unlock(&vas->share_lock);
}
+static inline int vas_seg_take_share(int type, struct vas_seg *seg)
+{
+ int ret;
+
+ spin_lock(&seg->share_lock);
+ if (type & MAY_WRITE) {
+ if ((seg->sharing & VAS_SHARE_READ_WRITE_MASK) == 0) {
+ seg->sharing += VAS_SHARE_WRITABLE;
+ ret = 1;
+ } else
+ ret = 0;
+ } else {
+ if ((seg->sharing & VAS_SHARE_WRITE_MASK) == 0) {
+ seg->sharing += VAS_SHARE_READABLE;
+ ret = 1;
+ } else
+ ret = 0;
+ }
+ spin_unlock(&seg->share_lock);
+
+ return ret;
+}
+
+static inline void vas_seg_put_share(int type, struct vas_seg *seg)
+{
+ spin_lock(&seg->share_lock);
+ if (type & MAY_WRITE)
+ seg->sharing -= VAS_SHARE_WRITABLE;
+ else
+ seg->sharing -= VAS_SHARE_READABLE;
+ spin_unlock(&seg->share_lock);
+}
+
/**
* Management of the memory maps.
**/
@@ -609,6 +929,59 @@ static int init_att_vas_mm(struct att_vas *avas, struct task_struct *owner)
return 0;
}
+static int init_vas_seg_mm(struct vas_seg *seg)
+{
+ struct mm_struct *mm;
+ unsigned long map_flags, page_prot_flags;
+ vm_flags_t vm_flags;
+ unsigned long map_addr;
+ int ret;
+
+ mm = mm_alloc();
+ if (!mm)
+ return -ENOMEM;
+
+ mm = mm_setup(mm);
+ if (!mm)
+ return -ENOMEM;
+
+ arch_pick_mmap_layout(mm);
+
+ map_flags = MAP_ANONYMOUS | MAP_FIXED;
+ page_prot_flags = PROT_READ | PROT_WRITE;
+ vm_flags = calc_vm_prot_bits(page_prot_flags, 0) |
+ calc_vm_flag_bits(map_flags) | mm->def_flags |
+ VM_DONTEXPAND | VM_DONTCOPY;
+
+ /* Find the possible mapping address for the VAS segment. */
+ map_addr = get_unmapped_area(mm, NULL, seg->start, seg->length,
+ 0, map_flags);
+ if (map_addr != seg->start) {
+ ret = -EFAULT;
+ goto out_free;
+ }
+
+ /* Insert the mapping into the mm_struct of the VAS segment. */
+ map_addr = mmap_region(mm, NULL, seg->start, seg->length,
+ vm_flags, 0);
+ if (map_addr != seg->start) {
+ ret = -EFAULT;
+ goto out_free;
+ }
+
+ /* Populate the VAS segments memory region. */
+ mm_populate(mm, seg->start, seg->length);
+
+ /* The mm_struct is properly setup. We are done here. */
+ seg->mm = mm;
+
+ return 0;
+
+out_free:
+ mmput(mm);
+ return ret;
+}
+
/**
* Lookup the corresponding vm_area in the referenced memory map.
*
@@ -1126,61 +1499,200 @@ static int task_unmerge(struct att_vas *avas, struct task_struct *tsk)
}
/**
- * Attach a VAS to a task -- update internal information ONLY
+ * Merge a VAS segment's memory map into a VAS memory map.
*
- * Requires that the VAS is already locked.
+ * Requires that the VAS and the VAS segment is already locked.
*
- * @param[in] avas: The pointer to the attached-VAS data structure
- * containing all the information of this attaching.
- * @param[in] tsk: The pointer to the task to which the VAS should be
- * attached.
- * @param[in] vas: The pointer to the VAS which should be attached.
+ * @param[in] vas: The pointer to the VAS into which the VAS segment should
+ * be merged.
+ * @param[in] seg: The pointer to the VAS segment that should be merged.
+ * @param[in] type: The type of attaching (see attach_segment for more
+ * information).
*
- * @returns: 0 on succes, -ERRNO otherwise.
+ * @returns: 0 on success, -ERRNO otherwise.
**/
-static int __vas_attach(struct att_vas *avas, struct task_struct *tsk,
- struct vas *vas)
+static int vas_seg_merge(struct vas *vas, struct vas_seg *seg, int type)
{
+ struct vm_area_struct *vma, *new_vma;
+ struct mm_struct *vas_mm, *seg_mm;
int ret;
- /* Before doing anything, synchronize the RSS-stat of the task. */
- sync_mm_rss(tsk->mm);
+ vas_mm = vas->mm;
+ seg_mm = seg->mm;
- /*
- * Try to acquire the VAS share with the proper type. This will ensure
- * that the different sharing possibilities of VAS are respected.
- */
- if (!vas_take_share(avas->type, vas)) {
- pr_vas_debug("VAS is already attached exclusively\n");
- return -EBUSY;
- }
+ dump_memory_map("Before VAS MM", vas_mm);
+ dump_memory_map("Before VAS segment MM", seg_mm);
- ret = vas_merge(avas, vas, avas->type);
- if (ret != 0)
- goto out_put_share;
+ if (down_write_killable(&vas_mm->mmap_sem))
+ return -EINTR;
+ down_read_nested(&seg_mm->mmap_sem, SINGLE_DEPTH_NESTING);
- ret = task_merge(avas, tsk);
- if (ret != 0)
- goto out_put_share;
+ /* Try to copy all VMAs of the VAS into the AS of the attached-VAS. */
+ for (vma = seg_mm->mmap; vma; vma = vma->vm_next) {
+ unsigned long merged_vm_flags = vma->vm_flags;
- vas->refcount++;
+ pr_vas_debug("Merging a VAS segment memory region (%#lx - %#lx)\n",
+ vma->vm_start, vma->vm_end);
- return 0;
+ /*
+ * Remove the writable bit from the vm_flags if the VAS segment
+ * is attached only readable.
+ */
+ if (!(type & MAY_WRITE))
+ merged_vm_flags &= ~(VM_WRITE | VM_MAYWRITE);
-out_put_share:
- vas_put_share(avas->type, vas);
- return ret;
-}
+ new_vma = __copy_vm_area(seg_mm, vma, vas_mm, merged_vm_flags);
+ if (!new_vma) {
+ pr_vas_debug("Failed to merge a VAS segment memory region (%#lx - %#lx)\n",
+ vma->vm_start, vma->vm_end);
+ ret = -EFAULT;
+ goto out_unlock;
+ }
-/**
- * Detach a VAS from a task -- update internal information ONLY
- *
- * Requires that the VAS is already locked.
- *
- * @param[in] avas: The pointer to the attached-VAS data structure
- * containing all the information of this attaching.
- * @param[in] tsk: The pointer to the task from which the VAS should be
- * detached.
+ /*
+ * Remember for the VMA that we just added it to the VAS that it
+ * actually belongs to the VAS segment.
+ */
+ new_vma->vas_reference = seg_mm;
+ }
+
+ ret = 0;
+
+out_unlock:
+ up_read(&seg_mm->mmap_sem);
+ up_write(&vas_mm->mmap_sem);
+
+ dump_memory_map("After VAS MM", vas_mm);
+ dump_memory_map("After VAS segment MM", seg_mm);
+
+ return ret;
+}
+
+/**
+ * Unmerge the VAS segment-related parts of a VAS' memory map back into the
+ * VAS segment's memory map.
+ *
+ * Requires that the VAS and the VAS segment are already locked.
+ *
+ * @param[in] vas: The pointer to the VAS from which the VAS segment
+ * related data should be taken.
+ * @param[in] seg: The pointer to the VAS segment for which the memory map
+ * should be updated again.
+ *
+ * @returns: 0 on success, -ERRNO otherwise.
+ **/
+static int vas_seg_unmerge(struct vas *vas, struct vas_seg *seg)
+{
+ struct vm_area_struct *vma, *next;
+ struct mm_struct *vas_mm, *seg_mm;
+ int ret;
+
+ vas_mm = vas->mm;
+ seg_mm = seg->mm;
+
+ dump_memory_map("Before VAS MM", vas_mm);
+ dump_memory_map("Before VAS segment MM", seg_mm);
+
+ if (down_write_killable(&vas_mm->mmap_sem))
+ return -EINTR;
+ down_write_nested(&seg_mm->mmap_sem, SINGLE_DEPTH_NESTING);
+
+ /* Update all memory regions which belonged to the VAS segment. */
+ for (vma = vas_mm->mmap, next = next_vma_safe(vma); vma;
+ vma = next, next = next_vma_safe(next)) {
+ struct mm_struct *ref_mm = vma->vas_reference;
+
+ if (ref_mm != seg_mm) {
+ pr_vas_debug("Skipping memory region (%#lx - %#lx) during VAS segment unmerging\n",
+ vma->vm_start, vma->vm_end);
+ continue;
+ } else {
+ struct vm_area_struct *upd_vma;
+
+ pr_vas_debug("Unmerging a VAS segment memory region (%#lx - %#lx)\n",
+ vma->vm_start, vma->vm_end);
+
+ upd_vma = __update_vm_area(vas_mm, vma, seg_mm, NULL);
+ if (!upd_vma) {
+ pr_vas_debug("Failed to unmerge a VAS segment memory region (%#lx - %#lx)\n",
+ vma->vm_start, vma->vm_end);
+ ret = -EFAULT;
+ goto out_unlock;
+ }
+ }
+
+ /* Remove the current VMA from the VAS memory map. */
+ __remove_vm_area(vas_mm, vma);
+ }
+
+ ret = 0;
+
+out_unlock:
+ up_write(&seg_mm->mmap_sem);
+ up_write(&vas_mm->mmap_sem);
+
+ dump_memory_map("After VAS MM", vas_mm);
+ dump_memory_map("After VAS segment MM", seg_mm);
+
+ return ret;
+}
+
+/**
+ * Attach a VAS to a task -- update internal information ONLY
+ *
+ * Requires that the VAS is already locked.
+ *
+ * @param[in] avas: The pointer to the attached-VAS data structure
+ * containing all the information of this attaching.
+ * @param[in] tsk: The pointer to the task to which the VAS should be
+ * attached.
+ * @param[in] vas: The pointer to the VAS which should be attached.
+ *
+ * @returns: 0 on success, -ERRNO otherwise.
+ **/
+static int __vas_attach(struct att_vas *avas, struct task_struct *tsk,
+ struct vas *vas)
+{
+ int ret;
+
+ /* Before doing anything, synchronize the RSS-stat of the task. */
+ sync_mm_rss(tsk->mm);
+
+ /*
+ * Try to acquire the VAS share with the proper type. This will ensure
+ * that the different sharing possibilities of VAS are respected.
+ */
+ if (!vas_take_share(avas->type, vas)) {
+ pr_vas_debug("VAS is already attached exclusively\n");
+ return -EBUSY;
+ }
+
+ ret = vas_merge(avas, vas, avas->type);
+ if (ret != 0)
+ goto out_put_share;
+
+ ret = task_merge(avas, tsk);
+ if (ret != 0)
+ goto out_put_share;
+
+ vas->refcount++;
+
+ return 0;
+
+out_put_share:
+ vas_put_share(avas->type, vas);
+ return ret;
+}
+
+/**
+ * Detach a VAS from a task -- update internal information ONLY
+ *
+ * Requires that the VAS is already locked.
+ *
+ * @param[in] avas: The pointer to the attached-VAS data structure
+ * containing all the information of this attaching.
+ * @param[in] tsk: The pointer to the task from which the VAS should be
+ * detached.
* @param[in] vas: The pointer to the VAS which should be detached.
*
* @returns: 0 on success, -ERRNO otherwise.
@@ -1209,6 +1721,83 @@ static int __vas_detach(struct att_vas *avas, struct task_struct *tsk,
return 0;
}
+/**
+ * Attach a VAS segment to a VAS -- update internal information ONLY
+ *
+ * Requires that the VAS segment and the VAS are already locked.
+ *
+ * @param aseg: The pointer tot he attached VAS segment data structure
+ * containing all the information of this attaching.
+ * @param vas: The pointer to the VAS to which the VAS segment should
+ * be attached.
+ * @param seg: The pointer to the VAS segment which should be attached.
+ *
+ * @returns: 0 on success, -ERRNO otherwise.
+ **/
+static int __vas_seg_attach(struct att_vas_seg *aseg, struct vas *vas,
+ struct vas_seg *seg)
+{
+ int ret;
+
+ /*
+ * Try to acquire the VAS segment share with the proper type. This will
+ * ensure that the different sharing possibilities of VAS segments are
+ * respected.
+ */
+ if (!vas_seg_take_share(aseg->type, seg)) {
+ pr_vas_debug("VAS segment is already attached to a VAS writable\n");
+ return -EBUSY;
+ }
+
+ /* Update the memory map of the VAS. */
+ ret = vas_seg_merge(vas, seg, aseg->type);
+ if (ret != 0)
+ goto out_put_share;
+
+ seg->refcount++;
+ vas->nr_segments++;
+
+ return 0;
+
+out_put_share:
+ vas_seg_put_share(aseg->type, seg);
+ return ret;
+}
+
+/**
+ * Detach a VAS segment from a VAS -- update internal information ONLY
+ *
+ * Requires that the VAS segment and the VAS are already locked.
+ *
+ * @param aseg: The pointer to the attached VAS segment data structure
+ * containing all the information of this attaching.
+ * @param vas: The pointer to the VAS from which the VAS segment should
+ * be detached.
+ * @param seg: The pointer to the VAS segment which should be detached.
+ *
+ * @returns: 0 on success, -ERRNO otherwise.
+ **/
+static int __vas_seg_detach(struct att_vas_seg *aseg, struct vas *vas,
+ struct vas_seg *seg)
+{
+ int ret;
+
+ /* Update the memory maps of the VAS segment and the VAS. */
+ ret = vas_seg_unmerge(vas, seg);
+ if (ret != 0)
+ return ret;
+
+ seg->refcount--;
+ vas->nr_segments--;
+
+ /*
+ * We unlock the VAS segment here to ensure our sharing properties.
+ */
+ vas_seg_put_share(aseg->type, seg);
+
+ return 0;
+}
+
static int __sync_from_task(struct mm_struct *avas_mm, struct mm_struct *tsk_mm)
{
struct vm_area_struct *vma;
@@ -1542,6 +2131,9 @@ int vas_create(const char *name, umode_t mode)
spin_lock_init(&vas->share_lock);
vas->sharing = 0;
+ INIT_LIST_HEAD(&vas->segments);
+ vas->nr_segments = 0;
+
vas->mode = mode & 0666;
vas->uid = current_uid();
vas->gid = current_gid();
@@ -1596,6 +2188,7 @@ EXPORT_SYMBOL(vas_find);
int vas_delete(int vid)
{
struct vas *vas;
+ struct att_vas_seg *aseg, *s_aseg;
int ret;
vas = vas_get(vid);
@@ -1618,6 +2211,39 @@ int vas_delete(int vid)
goto out_unlock;
}
+ /* Detach all still attached VAS segments. */
+ list_for_each_entry_safe(aseg, s_aseg, &vas->segments, vas_link) {
+ struct vas_seg *seg = aseg->seg;
+ int error;
+
+ pr_vas_debug("Detaching VAS segment - name: %s - from to-be-deleted VAS - name: %s\n",
+ seg->name, vas->name);
+
+ /*
+ * Make sure that our VAS segment reference is not removed while
+ * we work with it.
+ */
+ __vas_seg_get(seg);
+
+ /*
+ * Since the VAS from which we detach this VAS segment is going
+ * to be deleted anyways we can shorten the detaching process.
+ */
+ vas_seg_lock(seg);
+
+ error = __vas_seg_detach(aseg, vas, seg);
+ if (error != 0)
+ pr_alert("Detaching VAS segment from VAS failed with %d\n",
+ error);
+
+ list_del(&aseg->seg_link);
+ list_del(&aseg->vas_link);
+ __delete_att_vas_seg(aseg);
+
+ vas_seg_unlock(seg);
+ __vas_seg_put(seg);
+ }
+
vas_unlock(vas);
vas_remove(vas);
@@ -1908,19 +2534,433 @@ int vas_setattr(int vid, struct vas_attr *attr)
}
EXPORT_SYMBOL(vas_setattr);
+int vas_seg_create(const char *name, unsigned long start, unsigned long end,
+ umode_t mode)
+{
+ struct vas_seg *seg;
+ int ret;
+
+ if (!name || !PAGE_ALIGNED(start) || !PAGE_ALIGNED(end) ||
+ (end <= start))
+ return -EINVAL;
+
+ if (vas_seg_find(name) > 0)
+ return -EEXIST;
+
+ pr_vas_debug("Creating a new VAS segment - name: %s start: %#lx end: %#lx\n",
+ name, start, end);
+
+ /* Allocate and initialize the VAS segment. */
+ seg = __new_vas_seg();
+ if (!seg)
+ return -ENOMEM;
+
+ if (strscpy(seg->name, name, VAS_MAX_NAME_LENGTH) < 0) {
+ ret = -EINVAL;
+ goto out_free;
+ }
+
+ mutex_init(&seg->mtx);
+
+ seg->start = start;
+ seg->end = end;
+ seg->length = end - start;
+
+ ret = init_vas_seg_mm(seg);
+ if (ret != 0)
+ goto out_free;
+
+ seg->refcount = 0;
+
+ INIT_LIST_HEAD(&seg->attaches);
+ spin_lock_init(&seg->share_lock);
+ seg->sharing = 0;
+
+ seg->mode = mode & 0666;
+ seg->uid = current_uid();
+ seg->gid = current_gid();
+
+ ret = vas_seg_insert(seg);
+ if (ret != 0)
+ /*
+ * We don't need to free anything here. @vas_seg_insert will
+ * care for the deletion if something went wrong.
+ */
+ return ret;
+
+ return seg->id;
+
+out_free:
+ __delete_vas_seg(seg);
+ return ret;
+}
+EXPORT_SYMBOL(vas_seg_create);
+
+struct vas_seg *vas_seg_get(int sid)
+{
+ return vas_seg_lookup(sid);
+}
+EXPORT_SYMBOL(vas_seg_get);
+
+void vas_seg_put(struct vas_seg *seg)
+{
+ if (!seg)
+ return;
+
+ return __vas_seg_put(seg);
+}
+EXPORT_SYMBOL(vas_seg_put);
+
+int vas_seg_find(const char *name)
+{
+ struct vas_seg *seg;
+
+ seg = vas_seg_lookup_by_name(name);
+ if (seg) {
+ int sid = seg->id;
+
+ vas_seg_put(seg);
+ return sid;
+ }
+
+ return -ESRCH;
+}
+EXPORT_SYMBOL(vas_seg_find);
+
+int vas_seg_delete(int id)
+{
+ struct vas_seg *seg;
+ int ret;
+
+ seg = vas_seg_get(id);
+ if (!seg)
+ return -EINVAL;
+
+ pr_vas_debug("Deleting VAS segment - name: %s\n", seg->name);
+
+ vas_seg_lock(seg);
+
+ if (seg->refcount != 0) {
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
+ /* The user needs write permission to the VAS segment to delete it. */
+ ret = __check_permission(seg->uid, seg->gid, seg->mode, MAY_WRITE);
+ if (ret != 0) {
+ pr_vas_debug("User doesn't have the appropriate permissions to delete the VAS segment\n");
+ goto out_unlock;
+ }
+
+ vas_seg_unlock(seg);
+
+ vas_seg_remove(seg);
+ vas_seg_put(seg);
+
+ return 0;
+
+out_unlock:
+ vas_seg_unlock(seg);
+ vas_seg_put(seg);
+
+ return ret;
+}
+EXPORT_SYMBOL(vas_seg_delete);
+
+int vas_seg_attach(int vid, int sid, int type)
+{
+ struct vas *vas;
+ struct vas_seg *seg;
+ struct att_vas_seg *aseg;
+ int ret;
+
+ type &= (MAY_READ | MAY_WRITE);
+
+ vas = vas_get(vid);
+ if (!vas)
+ return -EINVAL;
+
+ seg = vas_seg_get(sid);
+ if (!seg) {
+ vas_put(vas);
+ return -EINVAL;
+ }
+
+ pr_vas_debug("Attaching VAS segment - name: %s - to VAS - name: %s - %s\n",
+ seg->name, vas->name, access_type_str(type));
+
+ vas_lock(vas);
+ vas_seg_lock(seg);
+
+ /*
+ * Before we can attach the VAS segment to the VAS we have to make some
+ * sanity checks.
+ */
+
+ /*
+ * 1: Check that the user has adequate permissions to attach the VAS
+ * segment in the given way.
+ */
+ ret = __check_permission(seg->uid, seg->gid, seg->mode, type);
+ if (ret != 0) {
+ pr_vas_debug("User doesn't have the appropriate permissions to attach the VAS segment\n");
+ goto out_unlock;
+ }
+
+ /*
+ * 2: The user needs write permission to the VAS to attach a VAS segment
+ * to it. Check that this requirement is fulfilled.
+ */
+ ret = __check_permission(vas->uid, vas->gid, vas->mode, MAY_WRITE);
+ if (ret != 0) {
+ pr_vas_debug("User doesn't have the appropriate permissions on the VAS to attach the VAS segment\n");
+ goto out_unlock;
+ }
+
+
+ /*
+ * 3: Check if the VAS is attached to a process. We do not support
+ * changes to an attached VAS. A VAS must not be attached to a process
+ * to be able to make changes to it. This ensures that the page tables
+ * are always properly initialized.
+ */
+ if (vas->refcount != 0) {
+ pr_vas_debug("VAS is attached to a process\n");
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
+ /*
+ * 4: Check if the VAS segment is already attached to this particular
+ * VAS. Double-attaching would lead to unintended behavior.
+ */
+ list_for_each_entry(aseg, &seg->attaches, seg_link) {
+ if (aseg->vas == vas) {
+ pr_vas_debug("VAS segment is already attached to the VAS\n");
+ ret = 0;
+ goto out_unlock;
+ }
+ }
+
+ /* 5: Check if we reached the maximum number of shares for this VAS. */
+ if (seg->refcount == VAS_MAX_SHARES) {
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
+ /*
+ * All sanity checks are done. It is safe to attach this VAS segment to
+ * the VAS now.
+ */
+
+ /* Allocate and initialize the attached VAS segment data structure. */
+ aseg = __new_att_vas_seg();
+ if (!aseg) {
+ ret = -ENOMEM;
+ goto out_unlock;
+ }
+
+ aseg->seg = seg;
+ aseg->vas = vas;
+ aseg->type = type;
+
+ ret = __vas_seg_attach(aseg, vas, seg);
+ if (ret != 0)
+ goto out_free_aseg;
+
+ list_add(&aseg->vas_link, &vas->segments);
+ list_add(&aseg->seg_link, &seg->attaches);
+
+ ret = 0;
+
+out_unlock:
+ vas_seg_unlock(seg);
+ vas_seg_put(seg);
+
+ vas_unlock(vas);
+ vas_put(vas);
+
+ return ret;
+
+out_free_aseg:
+ __delete_att_vas_seg(aseg);
+ goto out_unlock;
+}
+EXPORT_SYMBOL(vas_seg_attach);
+
+int vas_seg_detach(int vid, int sid)
+{
+ struct vas *vas;
+ struct vas_seg *seg;
+ struct att_vas_seg *aseg;
+ bool is_attached;
+ int ret;
+
+ vas = vas_get(vid);
+ if (!vas)
+ return -EINVAL;
+
+ vas_lock(vas);
+
+ is_attached = false;
+ list_for_each_entry(aseg, &vas->segments, vas_link) {
+ if (aseg->seg->id == sid) {
+ is_attached = true;
+ break;
+ }
+ }
+ if (!is_attached) {
+ pr_vas_debug("VAS segment is not attached to the given VAS\n");
+ ret = -EINVAL;
+ goto out_unlock_vas;
+ }
+
+ seg = aseg->seg;
+
+ /*
+ * Make sure that our reference to the VAS segment is not deleted while
+ * we are working with it.
+ */
+ __vas_seg_get(seg);
+
+ vas_seg_lock(seg);
+
+ pr_vas_debug("Detaching VAS segment - name: %s - from VAS - name: %s\n",
+ seg->name, vas->name);
+
+ /*
+ * Before we can detach the VAS segment from the VAS we have to do some
+ * sanity checks.
+ */
+
+ /*
+ * 1: Check if the VAS is attached to a process. We do not support
+ * changes to an attached VAS. A VAS must not be attached to a process
+ * to be able to make changes to it. This ensures that the page tables
+ * are always properly initialized.
+ */
+ if (vas->refcount != 0) {
+ pr_vas_debug("VAS is attached to a process\n");
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
+ /*
+ * All sanity checks are done. It is safe to detach the VAS segment from
+ * the VAS now.
+ */
+ ret = __vas_seg_detach(aseg, vas, seg);
+ if (ret != 0)
+ goto out_unlock;
+
+ list_del(&aseg->seg_link);
+ list_del(&aseg->vas_link);
+ __delete_att_vas_seg(aseg);
+
+ ret = 0;
+
+out_unlock:
+ vas_seg_unlock(seg);
+ __vas_seg_put(seg);
+
+out_unlock_vas:
+ vas_unlock(vas);
+ vas_put(vas);
+
+ return ret;
+}
+EXPORT_SYMBOL(vas_seg_detach);
+
+int vas_seg_getattr(int sid, struct vas_seg_attr *attr)
+{
+ struct vas_seg *seg;
+ struct user_namespace *ns = current_user_ns();
+
+ if (!attr)
+ return -EINVAL;
+
+ seg = vas_seg_get(sid);
+ if (!seg)
+ return -EINVAL;
+
+ pr_vas_debug("Getting attributes for VAS segment - name: %s\n",
+ seg->name);
+
+ vas_seg_lock(seg);
+
+ memset(attr, 0, sizeof(struct vas_seg_attr));
+ attr->mode = seg->mode;
+ attr->user = from_kuid(ns, seg->uid);
+ attr->group = from_kgid(ns, seg->gid);
+
+ vas_seg_unlock(seg);
+ vas_seg_put(seg);
+
+ return 0;
+}
+EXPORT_SYMBOL(vas_seg_getattr);
+
+int vas_seg_setattr(int sid, struct vas_seg_attr *attr)
+{
+ struct vas_seg *seg;
+ struct user_namespace *ns = current_user_ns();
+ int ret;
+
+ if (!attr)
+ return -EINVAL;
+
+ seg = vas_seg_get(sid);
+ if (!seg)
+ return -EINVAL;
+
+ pr_vas_debug("Setting attributes for VAS segment - name: %s\n",
+ seg->name);
+
+ vas_seg_lock(seg);
+
+ /*
+ * The user needs write permission to change attributes for the
+ * VAS segment.
+ */
+ ret = __check_permission(seg->uid, seg->gid, seg->mode, MAY_WRITE);
+ if (ret != 0) {
+ pr_vas_debug("User doesn't have the appropriate permissions to set attributes for the VAS segment\n");
+ goto out_unlock;
+ }
+
+ seg->mode = attr->mode & 0666;
+ seg->uid = make_kuid(ns, attr->user);
+ seg->gid = make_kgid(ns, attr->group);
+
+ ret = 0;
+
+out_unlock:
+ vas_seg_unlock(seg);
+ vas_seg_put(seg);
+
+ return ret;
+}
+EXPORT_SYMBOL(vas_seg_setattr);
+
void __init vas_init(void)
{
/* Create the SLAB caches for our data structures. */
vas_cachep = KMEM_CACHE(vas, SLAB_PANIC|SLAB_NOTRACK);
att_vas_cachep = KMEM_CACHE(att_vas, SLAB_PANIC|SLAB_NOTRACK);
vas_context_cachep = KMEM_CACHE(vas_context, SLAB_PANIC|SLAB_NOTRACK);
+ seg_cachep = KMEM_CACHE(vas_seg, SLAB_PANIC|SLAB_NOTRACK);
+ att_seg_cachep = KMEM_CACHE(att_vas_seg, SLAB_PANIC|SLAB_NOTRACK);
/* Initialize the internal management data structures. */
idr_init(&vases);
spin_lock_init(&vases_lock);
+ idr_init(&vas_segs);
+ spin_lock_init(&vas_segs_lock);
+
/* Initialize the place holder variables. */
INVALID_VAS = __new_vas();
+ INVALID_VAS_SEG = __new_vas_seg();
/* Initialize the VAS context of the init task. */
vas_clone(0, &init_task);
@@ -1941,6 +2981,12 @@ static int __init vas_sysfs_init(void)
return -ENOMEM;
}
+ vas_segs_kset = kset_create_and_add("vas_segs", NULL, kernel_kobj);
+ if (!vas_segs_kset) {
+ pr_err("Failed to initialize the VAS segment sysfs directory\n");
+ return -ENOMEM;
+ }
+
return 0;
}
postcore_initcall(vas_sysfs_init);
@@ -2186,3 +3232,105 @@ SYSCALL_DEFINE2(vas_setattr, int, vid, struct vas_attr __user *, uattr)
return vas_setattr(vid, &attr);
}
+
+SYSCALL_DEFINE4(vas_seg_create, const char __user *, name, unsigned long, begin,
+ unsigned long, end, umode_t, mode)
+{
+ char seg_name[VAS_MAX_NAME_LENGTH];
+ int len;
+
+ if (!name)
+ return -EINVAL;
+
+ len = strlen(name);
+ if (len >= VAS_MAX_NAME_LENGTH)
+ return -EINVAL;
+
+ if (copy_from_user(seg_name, name, len) != 0)
+ return -EFAULT;
+
+ seg_name[len] = '\0';
+
+ return vas_seg_create(seg_name, begin, end, mode);
+}
+
+SYSCALL_DEFINE1(vas_seg_delete, int, id)
+{
+ if (id < 0)
+ return -EINVAL;
+
+ return vas_seg_delete(id);
+}
+
+SYSCALL_DEFINE1(vas_seg_find, const char __user *, name)
+{
+ char seg_name[VAS_MAX_NAME_LENGTH];
+ int len;
+
+ if (!name)
+ return -EINVAL;
+
+ len = strlen(name);
+ if (len >= VAS_MAX_NAME_LENGTH)
+ return -EINVAL;
+
+ if (copy_from_user(seg_name, name, len) != 0)
+ return -EFAULT;
+
+ seg_name[len] = '\0';
+
+ return vas_seg_find(seg_name);
+}
+
+SYSCALL_DEFINE3(vas_seg_attach, int, vid, int, sid, int, type)
+{
+ int vas_acc_type;
+
+ if (vid < 0 || sid < 0)
+ return -EINVAL;
+
+ vas_acc_type = __build_vas_access_type(type);
+ if (vas_acc_type == -1)
+ return -EINVAL;
+
+ return vas_seg_attach(vid, sid, vas_acc_type);
+}
+
+SYSCALL_DEFINE2(vas_seg_detach, int, vid, int, sid)
+{
+ if (vid < 0 || sid < 0)
+ return -EINVAL;
+
+ return vas_seg_detach(vid, sid);
+}
+
+SYSCALL_DEFINE2(vas_seg_getattr, int, sid, struct vas_seg_attr __user *, uattr)
+{
+ struct vas_seg_attr attr;
+ int ret;
+
+ if (sid < 0 || !uattr)
+ return -EINVAL;
+
+ ret = vas_seg_getattr(sid, &attr);
+ if (ret != 0)
+ return ret;
+
+ if (copy_to_user(uattr, &attr, sizeof(struct vas_seg_attr)) != 0)
+ return -EFAULT;
+
+ return 0;
+}
+
+SYSCALL_DEFINE2(vas_seg_setattr, int, sid, struct vas_seg_attr __user *, uattr)
+{
+ struct vas_seg_attr attr;
+
+ if (sid < 0 || !uattr)
+ return -EINVAL;
+
+ if (copy_from_user(&attr, uattr, sizeof(struct vas_seg_attr)) != 0)
+ return -EFAULT;
+
+ return vas_seg_setattr(sid, &attr);
+}
--
2.12.0
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