diff options
Diffstat (limited to 'ipc/shm.c')
| -rw-r--r-- | ipc/shm.c | 1883 |
1 files changed, 1883 insertions, 0 deletions
diff --git a/ipc/shm.c b/ipc/shm.c new file mode 100644 index 0000000000..576a543b7c --- /dev/null +++ b/ipc/shm.c @@ -0,0 +1,1883 @@ +// 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 shm_file_data *sfd) +{ + 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) +{ + struct file *file = vma->vm_file; + struct shm_file_data *sfd = shm_file_data(file); + int err; + + /* Always call underlying open if present */ + if (sfd->vm_ops->open) + sfd->vm_ops->open(vma); + + err = __shm_open(sfd); + /* + * 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 shm_file_data *sfd) +{ + 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); +} + +static void shm_close(struct vm_area_struct *vma) +{ + struct file *file = vma->vm_file; + struct shm_file_data *sfd = shm_file_data(file); + + /* Always call underlying close if present */ + if (sfd->vm_ops->close) + sfd->vm_ops->close(vma); + + __shm_close(sfd); +} + +/* 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(sfd); + if (ret) + return ret; + + ret = call_mmap(sfd->file, vma); + if (ret) { + __shm_close(sfd); + 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, ¤t->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, 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; + VMA_ITERATOR(vmi, mm, addr); +#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. + */ + +#ifdef CONFIG_MMU + for_each_vma(vmi, vma) { + /* + * 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_vma_munmap(&vmi, vma, vma->vm_start, vma->vm_end, + NULL, false); + /* + * 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 = vma_next(&vmi); + break; + } + } + + /* + * 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) { + /* 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_vma_munmap(&vmi, vma, vma->vm_start, vma->vm_end, + NULL, false); + } + + vma = vma_next(&vmi); + } + +#else /* CONFIG_MMU */ + vma = vma_lookup(mm, addr); + /* 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 |