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 // SPDX-License-Identifier: GPL-2.0
 /*
  * linux/ipc/shm.c
  * Copyright (C) 1992, 1993 Krishna Balasubramanian
  *   Many improvements/fixes by Bruno Haible.
  * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
  * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
  *
  * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
  * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
  * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
  * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
  * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
  * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
  * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
  *
  * support for audit of ipc object properties and permission changes
  * Dustin Kirkland <dustin.kirkland@us.ibm.com>
  *
  * namespaces support
  * OpenVZ, SWsoft Inc.
  * Pavel Emelianov <xemul@openvz.org>
  *
  * Better ipc lock (kern_ipc_perm.lock) handling
  * Davidlohr Bueso <davidlohr.bueso@hp.com>, June 2013.
  */
 
 #include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/hugetlb.h>
 #include <linux/shm.h>
 #include <linux/init.h>
 #include <linux/file.h>
 #include <linux/mman.h>
 #include <linux/shmem_fs.h>
 #include <linux/security.h>
 #include <linux/syscalls.h>
 #include <linux/audit.h>
 #include <linux/capability.h>
 #include <linux/ptrace.h>
 #include <linux/seq_file.h>
 #include <linux/rwsem.h>
 #include <linux/nsproxy.h>
 #include <linux/mount.h>
 #include <linux/ipc_namespace.h>
 #include <linux/rhashtable.h>
 
 #include <linux/uaccess.h>
 
 #include "util.h"
 
 struct shmid_kernel /* private to the kernel */
 {
     struct kern_ipc_perm    shm_perm;
     struct file     *shm_file;
     unsigned long       shm_nattch;
     unsigned long       shm_segsz;
     time64_t        shm_atim;
     time64_t        shm_dtim;
     time64_t        shm_ctim;
     struct pid      *shm_cprid;
     struct pid      *shm_lprid;
     struct ucounts      *mlock_ucounts;
 
     /*
      * The task created the shm object, for
      * task_lock(shp->shm_creator)
      */
     struct task_struct  *shm_creator;
 
     /*
      * List by creator. task_lock(->shm_creator) required for read/write.
      * If list_empty(), then the creator is dead already.
      */
     struct list_head    shm_clist;
     struct ipc_namespace    *ns;
 } __randomize_layout;
 
 /* shm_mode upper byte flags */
 #define SHM_DEST    01000   /* segment will be destroyed on last detach */
 #define SHM_LOCKED  02000   /* segment will not be swapped */
 
 struct shm_file_data {
     int id;
     struct ipc_namespace *ns;
     struct file *file;
     const struct vm_operations_struct *vm_ops;
 };
 
 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
 
 static const struct file_operations shm_file_operations;
 static const struct vm_operations_struct shm_vm_ops;
 
 #define shm_ids(ns) ((ns)->ids[IPC_SHM_IDS])
 
 #define shm_unlock(shp)         \
     ipc_unlock(&(shp)->shm_perm)
 
 static int newseg(struct ipc_namespace *, struct ipc_params *);
 static void shm_open(struct vm_area_struct *vma);
 static void shm_close(struct vm_area_struct *vma);
 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
 #ifdef CONFIG_PROC_FS
 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
 #endif
 
 void shm_init_ns(struct ipc_namespace *ns)
 {
     ns->shm_ctlmax = SHMMAX;
     ns->shm_ctlall = SHMALL;
     ns->shm_ctlmni = SHMMNI;
     ns->shm_rmid_forced = 0;
     ns->shm_tot = 0;
     ipc_init_ids(&shm_ids(ns));
 }
 
 /*
  * Called with shm_ids.rwsem (writer) and the shp structure locked.
  * Only shm_ids.rwsem remains locked on exit.
  */
 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 {
     struct shmid_kernel *shp;
 
     shp = container_of(ipcp, struct shmid_kernel, shm_perm);
     WARN_ON(ns != shp->ns);
 
     if (shp->shm_nattch) {
         shp->shm_perm.mode |= SHM_DEST;
         /* Do not find it any more */
         ipc_set_key_private(&shm_ids(ns), &shp->shm_perm);
         shm_unlock(shp);
     } else
         shm_destroy(ns, shp);
 }
 
 #ifdef CONFIG_IPC_NS
 void shm_exit_ns(struct ipc_namespace *ns)
 {
     free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
     idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
     rhashtable_destroy(&ns->ids[IPC_SHM_IDS].key_ht);
 }
 #endif
 
 static int __init ipc_ns_init(void)
 {
     shm_init_ns(&init_ipc_ns);
     return 0;
 }
 
 pure_initcall(ipc_ns_init);
 
 void __init shm_init(void)
 {
     ipc_init_proc_interface("sysvipc/shm",
 #if BITS_PER_LONG <= 32
                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
 #else
                 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
 #endif
                 IPC_SHM_IDS, sysvipc_shm_proc_show);
 }
 
 static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
 {
     struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
 
     if (IS_ERR(ipcp))
         return ERR_CAST(ipcp);
 
     return container_of(ipcp, struct shmid_kernel, shm_perm);
 }
 
 static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
 {
     struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
 
     if (IS_ERR(ipcp))
         return ERR_CAST(ipcp);
 
     return container_of(ipcp, struct shmid_kernel, shm_perm);
 }
 
 /*
  * shm_lock_(check_) routines are called in the paths where the rwsem
  * is not necessarily held.
  */
 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 {
     struct kern_ipc_perm *ipcp;
 
     rcu_read_lock();
     ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
     if (IS_ERR(ipcp))
         goto err;
 
     ipc_lock_object(ipcp);
     /*
      * ipc_rmid() may have already freed the ID while ipc_lock_object()
      * was spinning: here verify that the structure is still valid.
      * Upon races with RMID, return -EIDRM, thus indicating that
      * the ID points to a removed identifier.
      */
     if (ipc_valid_object(ipcp)) {
         /* return a locked ipc object upon success */
         return container_of(ipcp, struct shmid_kernel, shm_perm);
     }
 
     ipc_unlock_object(ipcp);
     ipcp = ERR_PTR(-EIDRM);
 err:
     rcu_read_unlock();
     /*
      * Callers of shm_lock() must validate the status of the returned ipc
      * object pointer and error out as appropriate.
      */
     return ERR_CAST(ipcp);
 }
 
 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
 {
     rcu_read_lock();
     ipc_lock_object(&ipcp->shm_perm);
 }
 
 static void shm_rcu_free(struct rcu_head *head)
 {
     struct kern_ipc_perm *ptr = container_of(head, struct kern_ipc_perm,
                             rcu);
     struct shmid_kernel *shp = container_of(ptr, struct shmid_kernel,
                             shm_perm);
     security_shm_free(&shp->shm_perm);
     kfree(shp);
 }
 
 /*
  * It has to be called with shp locked.
  * It must be called before ipc_rmid()
  */
 static inline void shm_clist_rm(struct shmid_kernel *shp)
 {
     struct task_struct *creator;
 
     /* ensure that shm_creator does not disappear */
     rcu_read_lock();
 
     /*
      * A concurrent exit_shm may do a list_del_init() as well.
      * Just do nothing if exit_shm already did the work
      */
     if (!list_empty(&shp->shm_clist)) {
         /*
          * shp->shm_creator is guaranteed to be valid *only*
          * if shp->shm_clist is not empty.
          */
         creator = shp->shm_creator;
 
         task_lock(creator);
         /*
          * list_del_init() is a nop if the entry was already removed
          * from the list.
          */
         list_del_init(&shp->shm_clist);
         task_unlock(creator);
     }
     rcu_read_unlock();
 }
 
 static inline void shm_rmid(struct shmid_kernel *s)
 {
     shm_clist_rm(s);
     ipc_rmid(&shm_ids(s->ns), &s->shm_perm);
 }
 
 
 static int __shm_open(struct vm_area_struct *vma)
 {
     struct file *file = vma->vm_file;
     struct shm_file_data *sfd = shm_file_data(file);
     struct shmid_kernel *shp;
 
     shp = shm_lock(sfd->ns, sfd->id);
 
     if (IS_ERR(shp))
         return PTR_ERR(shp);
 
     if (shp->shm_file != sfd->file) {
         /* ID was reused */
         shm_unlock(shp);
         return -EINVAL;
     }
 
     shp->shm_atim = ktime_get_real_seconds();
     ipc_update_pid(&shp->shm_lprid, task_tgid(current));
     shp->shm_nattch++;
     shm_unlock(shp);
     return 0;
 }
 
 /* This is called by fork, once for every shm attach. */
 static void shm_open(struct vm_area_struct *vma)
 {
     int err = __shm_open(vma);
     /*
      * We raced in the idr lookup or with shm_destroy().
      * Either way, the ID is busted.
      */
     WARN_ON_ONCE(err);
 }
 
 /*
  * shm_destroy - free the struct shmid_kernel
  *
  * @ns: namespace
  * @shp: struct to free
  *
  * It has to be called with shp and shm_ids.rwsem (writer) locked,
  * but returns with shp unlocked and freed.
  */
 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 {
     struct file *shm_file;
 
     shm_file = shp->shm_file;
     shp->shm_file = NULL;
     ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
     shm_rmid(shp);
     shm_unlock(shp);
     if (!is_file_hugepages(shm_file))
         shmem_lock(shm_file, 0, shp->mlock_ucounts);
     fput(shm_file);
     ipc_update_pid(&shp->shm_cprid, NULL);
     ipc_update_pid(&shp->shm_lprid, NULL);
     ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 }
 
 /*
  * shm_may_destroy - identifies whether shm segment should be destroyed now
  *
  * Returns true if and only if there are no active users of the segment and
  * one of the following is true:
  *
  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
  *
  * 2) sysctl kernel.shm_rmid_forced is set to 1.
  */
 static bool shm_may_destroy(struct shmid_kernel *shp)
 {
     return (shp->shm_nattch == 0) &&
            (shp->ns->shm_rmid_forced ||
         (shp->shm_perm.mode & SHM_DEST));
 }
 
 /*
  * remove the attach descriptor vma.
  * free memory for segment if it is marked destroyed.
  * The descriptor has already been removed from the current->mm->mmap list
  * and will later be kfree()d.
  */
 static void shm_close(struct vm_area_struct *vma)
 {
     struct file *file = vma->vm_file;
     struct shm_file_data *sfd = shm_file_data(file);
     struct shmid_kernel *shp;
     struct ipc_namespace *ns = sfd->ns;
 
     down_write(&shm_ids(ns).rwsem);
     /* remove from the list of attaches of the shm segment */
     shp = shm_lock(ns, sfd->id);
 
     /*
      * We raced in the idr lookup or with shm_destroy().
      * Either way, the ID is busted.
      */
     if (WARN_ON_ONCE(IS_ERR(shp)))
         goto done; /* no-op */
 
     ipc_update_pid(&shp->shm_lprid, task_tgid(current));
     shp->shm_dtim = ktime_get_real_seconds();
     shp->shm_nattch--;
     if (shm_may_destroy(shp))
         shm_destroy(ns, shp);
     else
         shm_unlock(shp);
 done:
     up_write(&shm_ids(ns).rwsem);
 }
 
 /* Called with ns->shm_ids(ns).rwsem locked */
 static int shm_try_destroy_orphaned(int id, void *p, void *data)
 {
     struct ipc_namespace *ns = data;
     struct kern_ipc_perm *ipcp = p;
     struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 
     /*
      * We want to destroy segments without users and with already
      * exit'ed originating process.
      *
      * As shp->* are changed under rwsem, it's safe to skip shp locking.
      */
     if (!list_empty(&shp->shm_clist))
         return 0;
 
     if (shm_may_destroy(shp)) {
         shm_lock_by_ptr(shp);
         shm_destroy(ns, shp);
     }
     return 0;
 }
 
 void shm_destroy_orphaned(struct ipc_namespace *ns)
 {
     down_write(&shm_ids(ns).rwsem);
     if (shm_ids(ns).in_use)
         idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
     up_write(&shm_ids(ns).rwsem);
 }
 
 /* Locking assumes this will only be called with task == current */
 void exit_shm(struct task_struct *task)
 {
     for (;;) {
         struct shmid_kernel *shp;
         struct ipc_namespace *ns;
 
         task_lock(task);
 
         if (list_empty(&task->sysvshm.shm_clist)) {
             task_unlock(task);
             break;
         }
 
         shp = list_first_entry(&task->sysvshm.shm_clist, struct shmid_kernel,
                 shm_clist);
 
         /*
          * 1) Get pointer to the ipc namespace. It is worth to say
          * that this pointer is guaranteed to be valid because
          * shp lifetime is always shorter than namespace lifetime
          * in which shp lives.
          * We taken task_lock it means that shp won't be freed.
          */
         ns = shp->ns;
 
         /*
          * 2) If kernel.shm_rmid_forced is not set then only keep track of
          * which shmids are orphaned, so that a later set of the sysctl
          * can clean them up.
          */
         if (!ns->shm_rmid_forced)
             goto unlink_continue;
 
         /*
          * 3) get a reference to the namespace.
          *    The refcount could be already 0. If it is 0, then
          *    the shm objects will be free by free_ipc_work().
          */
         ns = get_ipc_ns_not_zero(ns);
         if (!ns) {
 unlink_continue:
             list_del_init(&shp->shm_clist);
             task_unlock(task);
             continue;
         }
 
         /*
          * 4) get a reference to shp.
          *   This cannot fail: shm_clist_rm() is called before
          *   ipc_rmid(), thus the refcount cannot be 0.
          */
         WARN_ON(!ipc_rcu_getref(&shp->shm_perm));
 
         /*
          * 5) unlink the shm segment from the list of segments
          *    created by current.
          *    This must be done last. After unlinking,
          *    only the refcounts obtained above prevent IPC_RMID
          *    from destroying the segment or the namespace.
          */
         list_del_init(&shp->shm_clist);
 
         task_unlock(task);
 
         /*
          * 6) we have all references
          *    Thus lock & if needed destroy shp.
          */
         down_write(&shm_ids(ns).rwsem);
         shm_lock_by_ptr(shp);
         /*
          * rcu_read_lock was implicitly taken in shm_lock_by_ptr, it's
          * safe to call ipc_rcu_putref here
          */
         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 
         if (ipc_valid_object(&shp->shm_perm)) {
             if (shm_may_destroy(shp))
                 shm_destroy(ns, shp);
             else
                 shm_unlock(shp);
         } else {
             /*
              * Someone else deleted the shp from namespace
              * idr/kht while we have waited.
              * Just unlock and continue.
              */
             shm_unlock(shp);
         }
 
         up_write(&shm_ids(ns).rwsem);
         put_ipc_ns(ns); /* paired with get_ipc_ns_not_zero */
     }
 }
 
 static vm_fault_t shm_fault(struct vm_fault *vmf)
 {
     struct file *file = vmf->vma->vm_file;
     struct shm_file_data *sfd = shm_file_data(file);
 
     return sfd->vm_ops->fault(vmf);
 }
 
 static int shm_may_split(struct vm_area_struct *vma, unsigned long addr)
 {
     struct file *file = vma->vm_file;
     struct shm_file_data *sfd = shm_file_data(file);
 
     if (sfd->vm_ops->may_split)
         return sfd->vm_ops->may_split(vma, addr);
 
     return 0;
 }
 
 static unsigned long shm_pagesize(struct vm_area_struct *vma)
 {
     struct file *file = vma->vm_file;
     struct shm_file_data *sfd = shm_file_data(file);
 
     if (sfd->vm_ops->pagesize)
         return sfd->vm_ops->pagesize(vma);
 
     return PAGE_SIZE;
 }
 
 #ifdef CONFIG_NUMA
 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 {
     struct file *file = vma->vm_file;
     struct shm_file_data *sfd = shm_file_data(file);
     int err = 0;
 
     if (sfd->vm_ops->set_policy)
         err = sfd->vm_ops->set_policy(vma, new);
     return err;
 }
 
 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
                     unsigned long addr)
 {
     struct file *file = vma->vm_file;
     struct shm_file_data *sfd = shm_file_data(file);
     struct mempolicy *pol = NULL;
 
     if (sfd->vm_ops->get_policy)
         pol = sfd->vm_ops->get_policy(vma, addr);
     else if (vma->vm_policy)
         pol = vma->vm_policy;
 
     return pol;
 }
 #endif
 
 static int shm_mmap(struct file *file, struct vm_area_struct *vma)
 {
     struct shm_file_data *sfd = shm_file_data(file);
     int ret;
 
     /*
      * In case of remap_file_pages() emulation, the file can represent an
      * IPC ID that was removed, and possibly even reused by another shm
      * segment already.  Propagate this case as an error to caller.
      */
     ret = __shm_open(vma);
     if (ret)
         return ret;
 
     ret = call_mmap(sfd->file, vma);
     if (ret) {
         shm_close(vma);
         return ret;
     }
     sfd->vm_ops = vma->vm_ops;
 #ifdef CONFIG_MMU
     WARN_ON(!sfd->vm_ops->fault);
 #endif
     vma->vm_ops = &shm_vm_ops;
     return 0;
 }
 
 static int shm_release(struct inode *ino, struct file *file)
 {
     struct shm_file_data *sfd = shm_file_data(file);
 
     put_ipc_ns(sfd->ns);
     fput(sfd->file);
     shm_file_data(file) = NULL;
     kfree(sfd);
     return 0;
 }
 
 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 {
     struct shm_file_data *sfd = shm_file_data(file);
 
     if (!sfd->file->f_op->fsync)
         return -EINVAL;
     return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
 }
 
 static long shm_fallocate(struct file *file, int mode, loff_t offset,
               loff_t len)
 {
     struct shm_file_data *sfd = shm_file_data(file);
 
     if (!sfd->file->f_op->fallocate)
         return -EOPNOTSUPP;
     return sfd->file->f_op->fallocate(file, mode, offset, len);
 }
 
 static unsigned long shm_get_unmapped_area(struct file *file,
     unsigned long addr, unsigned long len, unsigned long pgoff,
     unsigned long flags)
 {
     struct shm_file_data *sfd = shm_file_data(file);
 
     return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
                         pgoff, flags);
 }
 
 static const struct file_operations shm_file_operations = {
     .mmap       = shm_mmap,
     .fsync      = shm_fsync,
     .release    = shm_release,
     .get_unmapped_area  = shm_get_unmapped_area,
     .llseek     = noop_llseek,
     .fallocate  = shm_fallocate,
 };
 
 /*
  * shm_file_operations_huge is now identical to shm_file_operations,
  * but we keep it distinct for the sake of is_file_shm_hugepages().
  */
 static const struct file_operations shm_file_operations_huge = {
     .mmap       = shm_mmap,
     .fsync      = shm_fsync,
     .release    = shm_release,
     .get_unmapped_area  = shm_get_unmapped_area,
     .llseek     = noop_llseek,
     .fallocate  = shm_fallocate,
 };
 
 bool is_file_shm_hugepages(struct file *file)
 {
     return file->f_op == &shm_file_operations_huge;
 }
 
 static const struct vm_operations_struct shm_vm_ops = {
     .open   = shm_open, /* callback for a new vm-area open */
     .close  = shm_close,    /* callback for when the vm-area is released */
     .fault  = shm_fault,
     .may_split = shm_may_split,
     .pagesize = shm_pagesize,
 #if defined(CONFIG_NUMA)
     .set_policy = shm_set_policy,
     .get_policy = shm_get_policy,
 #endif
 };
 
 /**
  * newseg - Create a new shared memory segment
  * @ns: namespace
  * @params: ptr to the structure that contains key, size and shmflg
  *
  * Called with shm_ids.rwsem held as a writer.
  */
 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 {
     key_t key = params->key;
     int shmflg = params->flg;
     size_t size = params->u.size;
     int error;
     struct shmid_kernel *shp;
     size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
     struct file *file;
     char name[13];
     vm_flags_t acctflag = 0;
 
     if (size < SHMMIN || size > ns->shm_ctlmax)
         return -EINVAL;
 
     if (numpages << PAGE_SHIFT < size)
         return -ENOSPC;
 
     if (ns->shm_tot + numpages < ns->shm_tot ||
             ns->shm_tot + numpages > ns->shm_ctlall)
         return -ENOSPC;
 
     shp = kmalloc(sizeof(*shp), GFP_KERNEL_ACCOUNT);
     if (unlikely(!shp))
         return -ENOMEM;
 
     shp->shm_perm.key = key;
     shp->shm_perm.mode = (shmflg & S_IRWXUGO);
     shp->mlock_ucounts = NULL;
 
     shp->shm_perm.security = NULL;
     error = security_shm_alloc(&shp->shm_perm);
     if (error) {
         kfree(shp);
         return error;
     }
 
     sprintf(name, "SYSV%08x", key);
     if (shmflg & SHM_HUGETLB) {
         struct hstate *hs;
         size_t hugesize;
 
         hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
         if (!hs) {
             error = -EINVAL;
             goto no_file;
         }
         hugesize = ALIGN(size, huge_page_size(hs));
 
         /* hugetlb_file_setup applies strict accounting */
         if (shmflg & SHM_NORESERVE)
             acctflag = VM_NORESERVE;
         file = hugetlb_file_setup(name, hugesize, acctflag,
                 HUGETLB_SHMFS_INODE, (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
     } else {
         /*
          * Do not allow no accounting for OVERCOMMIT_NEVER, even
          * if it's asked for.
          */
         if  ((shmflg & SHM_NORESERVE) &&
                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
             acctflag = VM_NORESERVE;
         file = shmem_kernel_file_setup(name, size, acctflag);
     }
     error = PTR_ERR(file);
     if (IS_ERR(file))
         goto no_file;
 
     shp->shm_cprid = get_pid(task_tgid(current));
     shp->shm_lprid = NULL;
     shp->shm_atim = shp->shm_dtim = 0;
     shp->shm_ctim = ktime_get_real_seconds();
     shp->shm_segsz = size;
     shp->shm_nattch = 0;
     shp->shm_file = file;
     shp->shm_creator = current;
 
     /* ipc_addid() locks shp upon success. */
     error = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
     if (error < 0)
         goto no_id;
 
     shp->ns = ns;
 
     task_lock(current);
     list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
     task_unlock(current);
 
     /*
      * shmid gets reported as "inode#" in /proc/pid/maps.
      * proc-ps tools use this. Changing this will break them.
      */
     file_inode(file)->i_ino = shp->shm_perm.id;
 
     ns->shm_tot += numpages;
     error = shp->shm_perm.id;
 
     ipc_unlock_object(&shp->shm_perm);
     rcu_read_unlock();
     return error;
 
 no_id:
     ipc_update_pid(&shp->shm_cprid, NULL);
     ipc_update_pid(&shp->shm_lprid, NULL);
     fput(file);
     ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
     return error;
 no_file:
     call_rcu(&shp->shm_perm.rcu, shm_rcu_free);
     return error;
 }
 
 /*
  * Called with shm_ids.rwsem and ipcp locked.
  */
 static int shm_more_checks(struct kern_ipc_perm *ipcp, struct ipc_params *params)
 {
     struct shmid_kernel *shp;
 
     shp = container_of(ipcp, struct shmid_kernel, shm_perm);
     if (shp->shm_segsz < params->u.size)
         return -EINVAL;
 
     return 0;
 }
 
 long ksys_shmget(key_t key, size_t size, int shmflg)
 {
     struct ipc_namespace *ns;
     static const struct ipc_ops shm_ops = {
         .getnew = newseg,
         .associate = security_shm_associate,
         .more_checks = shm_more_checks,
     };
     struct ipc_params shm_params;
 
     ns = current->nsproxy->ipc_ns;
 
     shm_params.key = key;
     shm_params.flg = shmflg;
     shm_params.u.size = size;
 
     return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 }
 
 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 {
     return ksys_shmget(key, size, shmflg);
 }
 
 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 {
     switch (version) {
     case IPC_64:
         return copy_to_user(buf, in, sizeof(*in));
     case IPC_OLD:
         {
         struct shmid_ds out;
 
         memset(&out, 0, sizeof(out));
         ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
         out.shm_segsz   = in->shm_segsz;
         out.shm_atime   = in->shm_atime;
         out.shm_dtime   = in->shm_dtime;
         out.shm_ctime   = in->shm_ctime;
         out.shm_cpid    = in->shm_cpid;
         out.shm_lpid    = in->shm_lpid;
         out.shm_nattch  = in->shm_nattch;
 
         return copy_to_user(buf, &out, sizeof(out));
         }
     default:
         return -EINVAL;
     }
 }
 
 static inline unsigned long
 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 {
     switch (version) {
     case IPC_64:
         if (copy_from_user(out, buf, sizeof(*out)))
             return -EFAULT;
         return 0;
     case IPC_OLD:
         {
         struct shmid_ds tbuf_old;
 
         if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
             return -EFAULT;
 
         out->shm_perm.uid   = tbuf_old.shm_perm.uid;
         out->shm_perm.gid   = tbuf_old.shm_perm.gid;
         out->shm_perm.mode  = tbuf_old.shm_perm.mode;
 
         return 0;
         }
     default:
         return -EINVAL;
     }
 }
 
 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 {
     switch (version) {
     case IPC_64:
         return copy_to_user(buf, in, sizeof(*in));
     case IPC_OLD:
         {
         struct shminfo out;
 
         if (in->shmmax > INT_MAX)
             out.shmmax = INT_MAX;
         else
             out.shmmax = (int)in->shmmax;
 
         out.shmmin  = in->shmmin;
         out.shmmni  = in->shmmni;
         out.shmseg  = in->shmseg;
         out.shmall  = in->shmall;
 
         return copy_to_user(buf, &out, sizeof(out));
         }
     default:
         return -EINVAL;
     }
 }
 
 /*
  * Calculate and add used RSS and swap pages of a shm.
  * Called with shm_ids.rwsem held as a reader
  */
 static void shm_add_rss_swap(struct shmid_kernel *shp,
     unsigned long *rss_add, unsigned long *swp_add)
 {
     struct inode *inode;
 
     inode = file_inode(shp->shm_file);
 
     if (is_file_hugepages(shp->shm_file)) {
         struct address_space *mapping = inode->i_mapping;
         struct hstate *h = hstate_file(shp->shm_file);
         *rss_add += pages_per_huge_page(h) * mapping->nrpages;
     } else {
 #ifdef CONFIG_SHMEM
         struct shmem_inode_info *info = SHMEM_I(inode);
 
         spin_lock_irq(&info->lock);
         *rss_add += inode->i_mapping->nrpages;
         *swp_add += info->swapped;
         spin_unlock_irq(&info->lock);
 #else
         *rss_add += inode->i_mapping->nrpages;
 #endif
     }
 }
 
 /*
  * Called with shm_ids.rwsem held as a reader
  */
 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
         unsigned long *swp)
 {
     int next_id;
     int total, in_use;
 
     *rss = 0;
     *swp = 0;
 
     in_use = shm_ids(ns).in_use;
 
     for (total = 0, next_id = 0; total < in_use; next_id++) {
         struct kern_ipc_perm *ipc;
         struct shmid_kernel *shp;
 
         ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
         if (ipc == NULL)
             continue;
         shp = container_of(ipc, struct shmid_kernel, shm_perm);
 
         shm_add_rss_swap(shp, rss, swp);
 
         total++;
     }
 }
 
 /*
  * This function handles some shmctl commands which require the rwsem
  * to be held in write mode.
  * NOTE: no locks must be held, the rwsem is taken inside this function.
  */
 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
                struct shmid64_ds *shmid64)
 {
     struct kern_ipc_perm *ipcp;
     struct shmid_kernel *shp;
     int err;
 
     down_write(&shm_ids(ns).rwsem);
     rcu_read_lock();
 
     ipcp = ipcctl_obtain_check(ns, &shm_ids(ns), shmid, cmd,
                       &shmid64->shm_perm, 0);
     if (IS_ERR(ipcp)) {
         err = PTR_ERR(ipcp);
         goto out_unlock1;
     }
 
     shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 
     err = security_shm_shmctl(&shp->shm_perm, cmd);
     if (err)
         goto out_unlock1;
 
     switch (cmd) {
     case IPC_RMID:
         ipc_lock_object(&shp->shm_perm);
         /* do_shm_rmid unlocks the ipc object and rcu */
         do_shm_rmid(ns, ipcp);
         goto out_up;
     case IPC_SET:
         ipc_lock_object(&shp->shm_perm);
         err = ipc_update_perm(&shmid64->shm_perm, ipcp);
         if (err)
             goto out_unlock0;
         shp->shm_ctim = ktime_get_real_seconds();
         break;
     default:
         err = -EINVAL;
         goto out_unlock1;
     }
 
 out_unlock0:
     ipc_unlock_object(&shp->shm_perm);
 out_unlock1:
     rcu_read_unlock();
 out_up:
     up_write(&shm_ids(ns).rwsem);
     return err;
 }
 
 static int shmctl_ipc_info(struct ipc_namespace *ns,
                struct shminfo64 *shminfo)
 {
     int err = security_shm_shmctl(NULL, IPC_INFO);
     if (!err) {
         memset(shminfo, 0, sizeof(*shminfo));
         shminfo->shmmni = shminfo->shmseg = ns->shm_ctlmni;
         shminfo->shmmax = ns->shm_ctlmax;
         shminfo->shmall = ns->shm_ctlall;
         shminfo->shmmin = SHMMIN;
         down_read(&shm_ids(ns).rwsem);
         err = ipc_get_maxidx(&shm_ids(ns));
         up_read(&shm_ids(ns).rwsem);
         if (err < 0)
             err = 0;
     }
     return err;
 }
 
 static int shmctl_shm_info(struct ipc_namespace *ns,
                struct shm_info *shm_info)
 {
     int err = security_shm_shmctl(NULL, SHM_INFO);
     if (!err) {
         memset(shm_info, 0, sizeof(*shm_info));
         down_read(&shm_ids(ns).rwsem);
         shm_info->used_ids = shm_ids(ns).in_use;
         shm_get_stat(ns, &shm_info->shm_rss, &shm_info->shm_swp);
         shm_info->shm_tot = ns->shm_tot;
         shm_info->swap_attempts = 0;
         shm_info->swap_successes = 0;
         err = ipc_get_maxidx(&shm_ids(ns));
         up_read(&shm_ids(ns).rwsem);
         if (err < 0)
             err = 0;
     }
     return err;
 }
 
 static int shmctl_stat(struct ipc_namespace *ns, int shmid,
             int cmd, struct shmid64_ds *tbuf)
 {
     struct shmid_kernel *shp;
     int err;
 
     memset(tbuf, 0, sizeof(*tbuf));
 
     rcu_read_lock();
     if (cmd == SHM_STAT || cmd == SHM_STAT_ANY) {
         shp = shm_obtain_object(ns, shmid);
         if (IS_ERR(shp)) {
             err = PTR_ERR(shp);
             goto out_unlock;
         }
     } else { /* IPC_STAT */
         shp = shm_obtain_object_check(ns, shmid);
         if (IS_ERR(shp)) {
             err = PTR_ERR(shp);
             goto out_unlock;
         }
     }
 
     /*
      * Semantically SHM_STAT_ANY ought to be identical to
      * that functionality provided by the /proc/sysvipc/
      * interface. As such, only audit these calls and
      * do not do traditional S_IRUGO permission checks on
      * the ipc object.
      */
     if (cmd == SHM_STAT_ANY)
         audit_ipc_obj(&shp->shm_perm);
     else {
         err = -EACCES;
         if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
             goto out_unlock;
     }
 
     err = security_shm_shmctl(&shp->shm_perm, cmd);
     if (err)
         goto out_unlock;
 
     ipc_lock_object(&shp->shm_perm);
 
     if (!ipc_valid_object(&shp->shm_perm)) {
         ipc_unlock_object(&shp->shm_perm);
         err = -EIDRM;
         goto out_unlock;
     }
 
     kernel_to_ipc64_perm(&shp->shm_perm, &tbuf->shm_perm);
     tbuf->shm_segsz = shp->shm_segsz;
     tbuf->shm_atime = shp->shm_atim;
     tbuf->shm_dtime = shp->shm_dtim;
     tbuf->shm_ctime = shp->shm_ctim;
 #ifndef CONFIG_64BIT
     tbuf->shm_atime_high = shp->shm_atim >> 32;
     tbuf->shm_dtime_high = shp->shm_dtim >> 32;
     tbuf->shm_ctime_high = shp->shm_ctim >> 32;
 #endif
     tbuf->shm_cpid  = pid_vnr(shp->shm_cprid);
     tbuf->shm_lpid  = pid_vnr(shp->shm_lprid);
     tbuf->shm_nattch = shp->shm_nattch;
 
     if (cmd == IPC_STAT) {
         /*
          * As defined in SUS:
          * Return 0 on success
          */
         err = 0;
     } else {
         /*
          * SHM_STAT and SHM_STAT_ANY (both Linux specific)
          * Return the full id, including the sequence number
          */
         err = shp->shm_perm.id;
     }
 
     ipc_unlock_object(&shp->shm_perm);
 out_unlock:
     rcu_read_unlock();
     return err;
 }
 
 static int shmctl_do_lock(struct ipc_namespace *ns, int shmid, int cmd)
 {
     struct shmid_kernel *shp;
     struct file *shm_file;
     int err;
 
     rcu_read_lock();
     shp = shm_obtain_object_check(ns, shmid);
     if (IS_ERR(shp)) {
         err = PTR_ERR(shp);
         goto out_unlock1;
     }
 
     audit_ipc_obj(&(shp->shm_perm));
     err = security_shm_shmctl(&shp->shm_perm, cmd);
     if (err)
         goto out_unlock1;
 
     ipc_lock_object(&shp->shm_perm);
 
     /* check if shm_destroy() is tearing down shp */
     if (!ipc_valid_object(&shp->shm_perm)) {
         err = -EIDRM;
         goto out_unlock0;
     }
 
     if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
         kuid_t euid = current_euid();
 
         if (!uid_eq(euid, shp->shm_perm.uid) &&
             !uid_eq(euid, shp->shm_perm.cuid)) {
             err = -EPERM;
             goto out_unlock0;
         }
         if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
             err = -EPERM;
             goto out_unlock0;
         }
     }
 
     shm_file = shp->shm_file;
     if (is_file_hugepages(shm_file))
         goto out_unlock0;
 
     if (cmd == SHM_LOCK) {
         struct ucounts *ucounts = current_ucounts();
 
         err = shmem_lock(shm_file, 1, ucounts);
         if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
             shp->shm_perm.mode |= SHM_LOCKED;
             shp->mlock_ucounts = ucounts;
         }
         goto out_unlock0;
     }
 
     /* SHM_UNLOCK */
     if (!(shp->shm_perm.mode & SHM_LOCKED))
         goto out_unlock0;
     shmem_lock(shm_file, 0, shp->mlock_ucounts);
     shp->shm_perm.mode &= ~SHM_LOCKED;
     shp->mlock_ucounts = NULL;
     get_file(shm_file);
     ipc_unlock_object(&shp->shm_perm);
     rcu_read_unlock();
     shmem_unlock_mapping(shm_file->f_mapping);
 
     fput(shm_file);
     return err;
 
 out_unlock0:
     ipc_unlock_object(&shp->shm_perm);
 out_unlock1:
     rcu_read_unlock();
     return err;
 }
 
 static long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf, int version)
 {
     int err;
     struct ipc_namespace *ns;
     struct shmid64_ds sem64;
 
     if (cmd < 0 || shmid < 0)
         return -EINVAL;
 
     ns = current->nsproxy->ipc_ns;
 
     switch (cmd) {
     case IPC_INFO: {
         struct shminfo64 shminfo;
         err = shmctl_ipc_info(ns, &shminfo);
         if (err < 0)
             return err;
         if (copy_shminfo_to_user(buf, &shminfo, version))
             err = -EFAULT;
         return err;
     }
     case SHM_INFO: {
         struct shm_info shm_info;
         err = shmctl_shm_info(ns, &shm_info);
         if (err < 0)
             return err;
         if (copy_to_user(buf, &shm_info, sizeof(shm_info)))
             err = -EFAULT;
         return err;
     }
     case SHM_STAT:
     case SHM_STAT_ANY:
     case IPC_STAT: {
         err = shmctl_stat(ns, shmid, cmd, &sem64);
         if (err < 0)
             return err;
         if (copy_shmid_to_user(buf, &sem64, version))
             err = -EFAULT;
         return err;
     }
     case IPC_SET:
         if (copy_shmid_from_user(&sem64, buf, version))
             return -EFAULT;
         fallthrough;
     case IPC_RMID:
         return shmctl_down(ns, shmid, cmd, &sem64);
     case SHM_LOCK:
     case SHM_UNLOCK:
         return shmctl_do_lock(ns, shmid, cmd);
     default:
         return -EINVAL;
     }
 }
 
 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
 {
     return ksys_shmctl(shmid, cmd, buf, IPC_64);
 }
 
 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 long ksys_old_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
 {
     int version = ipc_parse_version(&cmd);
 
     return ksys_shmctl(shmid, cmd, buf, version);
 }
 
 SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
 {
     return ksys_old_shmctl(shmid, cmd, buf);
 }
 #endif
 
 #ifdef CONFIG_COMPAT
 
 struct compat_shmid_ds {
     struct compat_ipc_perm shm_perm;
     int shm_segsz;
     old_time32_t shm_atime;
     old_time32_t shm_dtime;
     old_time32_t shm_ctime;
     compat_ipc_pid_t shm_cpid;
     compat_ipc_pid_t shm_lpid;
     unsigned short shm_nattch;
     unsigned short shm_unused;
     compat_uptr_t shm_unused2;
     compat_uptr_t shm_unused3;
 };
 
 struct compat_shminfo64 {
     compat_ulong_t shmmax;
     compat_ulong_t shmmin;
     compat_ulong_t shmmni;
     compat_ulong_t shmseg;
     compat_ulong_t shmall;
     compat_ulong_t __unused1;
     compat_ulong_t __unused2;
     compat_ulong_t __unused3;
     compat_ulong_t __unused4;
 };
 
 struct compat_shm_info {
     compat_int_t used_ids;
     compat_ulong_t shm_tot, shm_rss, shm_swp;
     compat_ulong_t swap_attempts, swap_successes;
 };
 
 static int copy_compat_shminfo_to_user(void __user *buf, struct shminfo64 *in,
                     int version)
 {
     if (in->shmmax > INT_MAX)
         in->shmmax = INT_MAX;
     if (version == IPC_64) {
         struct compat_shminfo64 info;
         memset(&info, 0, sizeof(info));
         info.shmmax = in->shmmax;
         info.shmmin = in->shmmin;
         info.shmmni = in->shmmni;
         info.shmseg = in->shmseg;
         info.shmall = in->shmall;
         return copy_to_user(buf, &info, sizeof(info));
     } else {
         struct shminfo info;
         memset(&info, 0, sizeof(info));
         info.shmmax = in->shmmax;
         info.shmmin = in->shmmin;
         info.shmmni = in->shmmni;
         info.shmseg = in->shmseg;
         info.shmall = in->shmall;
         return copy_to_user(buf, &info, sizeof(info));
     }
 }
 
 static int put_compat_shm_info(struct shm_info *ip,
                 struct compat_shm_info __user *uip)
 {
     struct compat_shm_info info;
 
     memset(&info, 0, sizeof(info));
     info.used_ids = ip->used_ids;
     info.shm_tot = ip->shm_tot;
     info.shm_rss = ip->shm_rss;
     info.shm_swp = ip->shm_swp;
     info.swap_attempts = ip->swap_attempts;
     info.swap_successes = ip->swap_successes;
     return copy_to_user(uip, &info, sizeof(info));
 }
 
 static int copy_compat_shmid_to_user(void __user *buf, struct shmid64_ds *in,
                     int version)
 {
     if (version == IPC_64) {
         struct compat_shmid64_ds v;
         memset(&v, 0, sizeof(v));
         to_compat_ipc64_perm(&v.shm_perm, &in->shm_perm);
         v.shm_atime  = lower_32_bits(in->shm_atime);
         v.shm_atime_high = upper_32_bits(in->shm_atime);
         v.shm_dtime  = lower_32_bits(in->shm_dtime);
         v.shm_dtime_high = upper_32_bits(in->shm_dtime);
         v.shm_ctime  = lower_32_bits(in->shm_ctime);
         v.shm_ctime_high = upper_32_bits(in->shm_ctime);
         v.shm_segsz = in->shm_segsz;
         v.shm_nattch = in->shm_nattch;
         v.shm_cpid = in->shm_cpid;
         v.shm_lpid = in->shm_lpid;
         return copy_to_user(buf, &v, sizeof(v));
     } else {
         struct compat_shmid_ds v;
         memset(&v, 0, sizeof(v));
         to_compat_ipc_perm(&v.shm_perm, &in->shm_perm);
         v.shm_perm.key = in->shm_perm.key;
         v.shm_atime = in->shm_atime;
         v.shm_dtime = in->shm_dtime;
         v.shm_ctime = in->shm_ctime;
         v.shm_segsz = in->shm_segsz;
         v.shm_nattch = in->shm_nattch;
         v.shm_cpid = in->shm_cpid;
         v.shm_lpid = in->shm_lpid;
         return copy_to_user(buf, &v, sizeof(v));
     }
 }
 
 static int copy_compat_shmid_from_user(struct shmid64_ds *out, void __user *buf,
                     int version)
 {
     memset(out, 0, sizeof(*out));
     if (version == IPC_64) {
         struct compat_shmid64_ds __user *p = buf;
         return get_compat_ipc64_perm(&out->shm_perm, &p->shm_perm);
     } else {
         struct compat_shmid_ds __user *p = buf;
         return get_compat_ipc_perm(&out->shm_perm, &p->shm_perm);
     }
 }
 
 static long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr, int version)
 {
     struct ipc_namespace *ns;
     struct shmid64_ds sem64;
     int err;
 
     ns = current->nsproxy->ipc_ns;
 
     if (cmd < 0 || shmid < 0)
         return -EINVAL;
 
     switch (cmd) {
     case IPC_INFO: {
         struct shminfo64 shminfo;
         err = shmctl_ipc_info(ns, &shminfo);
         if (err < 0)
             return err;
         if (copy_compat_shminfo_to_user(uptr, &shminfo, version))
             err = -EFAULT;
         return err;
     }
     case SHM_INFO: {
         struct shm_info shm_info;
         err = shmctl_shm_info(ns, &shm_info);
         if (err < 0)
             return err;
         if (put_compat_shm_info(&shm_info, uptr))
             err = -EFAULT;
         return err;
     }
     case IPC_STAT:
     case SHM_STAT_ANY:
     case SHM_STAT:
         err = shmctl_stat(ns, shmid, cmd, &sem64);
         if (err < 0)
             return err;
         if (copy_compat_shmid_to_user(uptr, &sem64, version))
             err = -EFAULT;
         return err;
 
     case IPC_SET:
         if (copy_compat_shmid_from_user(&sem64, uptr, version))
             return -EFAULT;
         fallthrough;
     case IPC_RMID:
         return shmctl_down(ns, shmid, cmd, &sem64);
     case SHM_LOCK:
     case SHM_UNLOCK:
         return shmctl_do_lock(ns, shmid, cmd);
     default:
         return -EINVAL;
     }
     return err;
 }
 
 COMPAT_SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, void __user *, uptr)
 {
     return compat_ksys_shmctl(shmid, cmd, uptr, IPC_64);
 }
 
 #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr)
 {
     int version = compat_ipc_parse_version(&cmd);
 
     return compat_ksys_shmctl(shmid, cmd, uptr, version);
 }
 
 COMPAT_SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, void __user *, uptr)
 {
     return compat_ksys_old_shmctl(shmid, cmd, uptr);
 }
 #endif
 #endif
 
 /*
  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
  *
  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
  * "raddr" thing points to kernel space, and there has to be a wrapper around
  * this.
  */
 long do_shmat(int shmid, char __user *shmaddr, int shmflg,
           ulong *raddr, unsigned long shmlba)
 {
     struct shmid_kernel *shp;
     unsigned long addr = (unsigned long)shmaddr;
     unsigned long size;
     struct file *file, *base;
     int    err;
     unsigned long flags = MAP_SHARED;
     unsigned long prot;
     int acc_mode;
     struct ipc_namespace *ns;
     struct shm_file_data *sfd;
     int f_flags;
     unsigned long populate = 0;
 
     err = -EINVAL;
     if (shmid < 0)
         goto out;
 
     if (addr) {
         if (addr & (shmlba - 1)) {
             if (shmflg & SHM_RND) {
                 addr &= ~(shmlba - 1);  /* round down */
 
                 /*
                  * Ensure that the round-down is non-nil
                  * when remapping. This can happen for
                  * cases when addr < shmlba.
                  */
                 if (!addr && (shmflg & SHM_REMAP))
                     goto out;
             } else
 #ifndef __ARCH_FORCE_SHMLBA
                 if (addr & ~PAGE_MASK)
 #endif
                     goto out;
         }
 
         flags |= MAP_FIXED;
     } else if ((shmflg & SHM_REMAP))
         goto out;
 
     if (shmflg & SHM_RDONLY) {
         prot = PROT_READ;
         acc_mode = S_IRUGO;
         f_flags = O_RDONLY;
     } else {
         prot = PROT_READ | PROT_WRITE;
         acc_mode = S_IRUGO | S_IWUGO;
         f_flags = O_RDWR;
     }
     if (shmflg & SHM_EXEC) {
         prot |= PROT_EXEC;
         acc_mode |= S_IXUGO;
     }
 
     /*
      * We cannot rely on the fs check since SYSV IPC does have an
      * additional creator id...
      */
     ns = current->nsproxy->ipc_ns;
     rcu_read_lock();
     shp = shm_obtain_object_check(ns, shmid);
     if (IS_ERR(shp)) {
         err = PTR_ERR(shp);
         goto out_unlock;
     }
 
     err = -EACCES;
     if (ipcperms(ns, &shp->shm_perm, acc_mode))
         goto out_unlock;
 
     err = security_shm_shmat(&shp->shm_perm, shmaddr, shmflg);
     if (err)
         goto out_unlock;
 
     ipc_lock_object(&shp->shm_perm);
 
     /* check if shm_destroy() is tearing down shp */
     if (!ipc_valid_object(&shp->shm_perm)) {
         ipc_unlock_object(&shp->shm_perm);
         err = -EIDRM;
         goto out_unlock;
     }
 
     /*
      * We need to take a reference to the real shm file to prevent the
      * pointer from becoming stale in cases where the lifetime of the outer
      * file extends beyond that of the shm segment.  It's not usually
      * possible, but it can happen during remap_file_pages() emulation as
      * that unmaps the memory, then does ->mmap() via file reference only.
      * We'll deny the ->mmap() if the shm segment was since removed, but to
      * detect shm ID reuse we need to compare the file pointers.
      */
     base = get_file(shp->shm_file);
     shp->shm_nattch++;
     size = i_size_read(file_inode(base));
     ipc_unlock_object(&shp->shm_perm);
     rcu_read_unlock();
 
     err = -ENOMEM;
     sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
     if (!sfd) {
         fput(base);
         goto out_nattch;
     }
 
     file = alloc_file_clone(base, f_flags,
               is_file_hugepages(base) ?
                 &shm_file_operations_huge :
                 &shm_file_operations);
     err = PTR_ERR(file);
     if (IS_ERR(file)) {
         kfree(sfd);
         fput(base);
         goto out_nattch;
     }
 
     sfd->id = shp->shm_perm.id;
     sfd->ns = get_ipc_ns(ns);
     sfd->file = base;
     sfd->vm_ops = NULL;
     file->private_data = sfd;
 
     err = security_mmap_file(file, prot, flags);
     if (err)
         goto out_fput;
 
     if (mmap_write_lock_killable(current->mm)) {
         err = -EINTR;
         goto out_fput;
     }
 
     if (addr && !(shmflg & SHM_REMAP)) {
         err = -EINVAL;
         if (addr + size < addr)
             goto invalid;
 
         if (find_vma_intersection(current->mm, addr, addr + size))
             goto invalid;
     }
 
     addr = do_mmap(file, addr, size, prot, flags, 0, &populate, NULL);
     *raddr = addr;
     err = 0;
     if (IS_ERR_VALUE(addr))
         err = (long)addr;
 invalid:
     mmap_write_unlock(current->mm);
     if (populate)
         mm_populate(addr, populate);
 
 out_fput:
     fput(file);
 
 out_nattch:
     down_write(&shm_ids(ns).rwsem);
     shp = shm_lock(ns, shmid);
     shp->shm_nattch--;
 
     if (shm_may_destroy(shp))
         shm_destroy(ns, shp);
     else
         shm_unlock(shp);
     up_write(&shm_ids(ns).rwsem);
     return err;
 
 out_unlock:
     rcu_read_unlock();
 out:
     return err;
 }
 
 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
 {
     unsigned long ret;
     long err;
 
     err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
     if (err)
         return err;
     force_successful_syscall_return();
     return (long)ret;
 }
 
 #ifdef CONFIG_COMPAT
 
 #ifndef COMPAT_SHMLBA
 #define COMPAT_SHMLBA   SHMLBA
 #endif
 
 COMPAT_SYSCALL_DEFINE3(shmat, int, shmid, compat_uptr_t, shmaddr, int, shmflg)
 {
     unsigned long ret;
     long err;
 
     err = do_shmat(shmid, compat_ptr(shmaddr), shmflg, &ret, COMPAT_SHMLBA);
     if (err)
         return err;
     force_successful_syscall_return();
     return (long)ret;
 }
 #endif
 
 /*
  * detach and kill segment if marked destroyed.
  * The work is done in shm_close.
  */
 long ksys_shmdt(char __user *shmaddr)
 {
     struct mm_struct *mm = current->mm;
     struct vm_area_struct *vma;
     unsigned long addr = (unsigned long)shmaddr;
     int retval = -EINVAL;
 #ifdef CONFIG_MMU
     loff_t size = 0;
     struct file *file;
     struct vm_area_struct *next;
 #endif
 
     if (addr & ~PAGE_MASK)
         return retval;
 
     if (mmap_write_lock_killable(mm))
         return -EINTR;
 
     /*
      * This function tries to be smart and unmap shm segments that
      * were modified by partial mlock or munmap calls:
      * - It first determines the size of the shm segment that should be
      *   unmapped: It searches for a vma that is backed by shm and that
      *   started at address shmaddr. It records it's size and then unmaps
      *   it.
      * - Then it unmaps all shm vmas that started at shmaddr and that
      *   are within the initially determined size and that are from the
      *   same shm segment from which we determined the size.
      * Errors from do_munmap are ignored: the function only fails if
      * it's called with invalid parameters or if it's called to unmap
      * a part of a vma. Both calls in this function are for full vmas,
      * the parameters are directly copied from the vma itself and always
      * valid - therefore do_munmap cannot fail. (famous last words?)
      */
     /*
      * If it had been mremap()'d, the starting address would not
      * match the usual checks anyway. So assume all vma's are
      * above the starting address given.
      */
     vma = find_vma(mm, addr);
 
 #ifdef CONFIG_MMU
     while (vma) {
         next = vma->vm_next;
 
         /*
          * Check if the starting address would match, i.e. it's
          * a fragment created by mprotect() and/or munmap(), or it
          * otherwise it starts at this address with no hassles.
          */
         if ((vma->vm_ops == &shm_vm_ops) &&
             (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
 
             /*
              * Record the file of the shm segment being
              * unmapped.  With mremap(), someone could place
              * page from another segment but with equal offsets
              * in the range we are unmapping.
              */
             file = vma->vm_file;
             size = i_size_read(file_inode(vma->vm_file));
             do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
             /*
              * We discovered the size of the shm segment, so
              * break out of here and fall through to the next
              * loop that uses the size information to stop
              * searching for matching vma's.
              */
             retval = 0;
             vma = next;
             break;
         }
         vma = next;
     }
 
     /*
      * We need look no further than the maximum address a fragment
      * could possibly have landed at. Also cast things to loff_t to
      * prevent overflows and make comparisons vs. equal-width types.
      */
     size = PAGE_ALIGN(size);
     while (vma && (loff_t)(vma->vm_end - addr) <= size) {
         next = vma->vm_next;
 
         /* finding a matching vma now does not alter retval */
         if ((vma->vm_ops == &shm_vm_ops) &&
             ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
             (vma->vm_file == file))
             do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
         vma = next;
     }
 
 #else   /* CONFIG_MMU */
     /* under NOMMU conditions, the exact address to be destroyed must be
      * given
      */
     if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
         retval = 0;
     }
 
 #endif
 
     mmap_write_unlock(mm);
     return retval;
 }
 
 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
 {
     return ksys_shmdt(shmaddr);
 }
 
 #ifdef CONFIG_PROC_FS
 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
 {
     struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
     struct user_namespace *user_ns = seq_user_ns(s);
     struct kern_ipc_perm *ipcp = it;
     struct shmid_kernel *shp;
     unsigned long rss = 0, swp = 0;
 
     shp = container_of(ipcp, struct shmid_kernel, shm_perm);
     shm_add_rss_swap(shp, &rss, &swp);
 
 #if BITS_PER_LONG <= 32
 #define SIZE_SPEC "%10lu"
 #else
 #define SIZE_SPEC "%21lu"
 #endif
 
     seq_printf(s,
            "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
            "%5lu %5u %5u %5u %5u %10llu %10llu %10llu "
            SIZE_SPEC " " SIZE_SPEC "\n",
            shp->shm_perm.key,
            shp->shm_perm.id,
            shp->shm_perm.mode,
            shp->shm_segsz,
            pid_nr_ns(shp->shm_cprid, pid_ns),
            pid_nr_ns(shp->shm_lprid, pid_ns),
            shp->shm_nattch,
            from_kuid_munged(user_ns, shp->shm_perm.uid),
            from_kgid_munged(user_ns, shp->shm_perm.gid),
            from_kuid_munged(user_ns, shp->shm_perm.cuid),
            from_kgid_munged(user_ns, shp->shm_perm.cgid),
            shp->shm_atim,
            shp->shm_dtim,
            shp->shm_ctim,
            rss * PAGE_SIZE,
            swp * PAGE_SIZE);
 
     return 0;
 }
 #endif

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