/* * 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 <asm/uaccess.h> #include "util.h" 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); if (shp->shm_nattch) { shp->shm_perm.mode |= SHM_DEST; /* Do not find it any more */ shp->shm_perm.key = IPC_PRIVATE; 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); } #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(&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 = ipc_lock(&shm_ids(ns), id); if (IS_ERR(ipcp)) return (struct shmid_kernel *)ipcp; return container_of(ipcp, struct shmid_kernel, shm_perm); } 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 ipc_rcu *p = container_of(head, struct ipc_rcu, rcu); struct shmid_kernel *shp = ipc_rcu_to_struct(p); security_shm_free(shp); ipc_rcu_free(head); } static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s) { ipc_rmid(&shm_ids(ns), &s->shm_perm); } /* 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); struct shmid_kernel *shp; shp = shm_lock(sfd->ns, sfd->id); BUG_ON(IS_ERR(shp)); shp->shm_atim = get_seconds(); shp->shm_lprid = task_tgid_vnr(current); shp->shm_nattch++; shm_unlock(shp); } /* * 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(ns, shp); shm_unlock(shp); if (!is_file_hugepages(shm_file)) shmem_lock(shm_file, 0, shp->mlock_user); else if (shp->mlock_user) user_shm_unlock(file_inode(shm_file)->i_size, shp->mlock_user); fput(shm_file); ipc_rcu_putref(shp, 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 ipc_namespace *ns, struct shmid_kernel *shp) { return (shp->shm_nattch == 0) && (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); BUG_ON(IS_ERR(shp)); shp->shm_lprid = task_tgid_vnr(current); shp->shm_dtim = get_seconds(); shp->shm_nattch--; if (shm_may_destroy(ns, shp)) shm_destroy(ns, shp); else shm_unlock(shp); up_write(&shm_ids(ns).rwsem); } /* Called with ns->shm_ids(ns).rwsem locked */ static int shm_try_destroy_current(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); if (shp->shm_creator != current) return 0; /* * Mark it as orphaned to destroy the segment when * kernel.shm_rmid_forced is changed. * It is noop if the following shm_may_destroy() returns true. */ shp->shm_creator = NULL; /* * Don't even try to destroy it. If shm_rmid_forced=0 and IPC_RMID * is not set, it shouldn't be deleted here. */ if (!ns->shm_rmid_forced) return 0; if (shm_may_destroy(ns, shp)) { shm_lock_by_ptr(shp); shm_destroy(ns, shp); } return 0; } /* 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 (shp->shm_creator != NULL) return 0; if (shm_may_destroy(ns, 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); } void exit_shm(struct task_struct *task) { struct ipc_namespace *ns = task->nsproxy->ipc_ns; if (shm_ids(ns).in_use == 0) return; /* Destroy all already created segments, but not mapped yet */ down_write(&shm_ids(ns).rwsem); if (shm_ids(ns).in_use) idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns); up_write(&shm_ids(ns).rwsem); } static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf) { struct file *file = vma->vm_file; struct shm_file_data *sfd = shm_file_data(file); return sfd->vm_ops->fault(vma, vmf); } #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; ret = sfd->file->f_op->mmap(sfd->file, vma); if (ret != 0) return ret; sfd->vm_ops = vma->vm_ops; #ifdef CONFIG_MMU BUG_ON(!sfd->vm_ops->fault); #endif vma->vm_ops = &shm_vm_ops; shm_open(vma); return ret; } static int shm_release(struct inode *ino, struct file *file) { struct shm_file_data *sfd = shm_file_data(file); put_ipc_ns(sfd->ns); 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, #ifndef CONFIG_MMU .get_unmapped_area = shm_get_unmapped_area, #endif .llseek = noop_llseek, .fallocate = shm_fallocate, }; 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, }; int 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, #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]; int id; vm_flags_t acctflag = 0; if (size < SHMMIN || size > ns->shm_ctlmax) return -EINVAL; if (ns->shm_tot + numpages > ns->shm_ctlall) return -ENOSPC; shp = ipc_rcu_alloc(sizeof(*shp)); if (!shp) return -ENOMEM; shp->shm_perm.key = key; shp->shm_perm.mode = (shmflg & S_IRWXUGO); shp->mlock_user = NULL; shp->shm_perm.security = NULL; error = security_shm_alloc(shp); if (error) { ipc_rcu_putref(shp, ipc_rcu_free); 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, &shp->mlock_user, 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_file_setup(name, size, acctflag); } error = PTR_ERR(file); if (IS_ERR(file)) goto no_file; id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni); if (id < 0) { error = id; goto no_id; } shp->shm_cprid = task_tgid_vnr(current); shp->shm_lprid = 0; shp->shm_atim = shp->shm_dtim = 0; shp->shm_ctim = get_seconds(); shp->shm_segsz = size; shp->shm_nattch = 0; shp->shm_file = file; shp->shm_creator = 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: if (is_file_hugepages(file) && shp->mlock_user) user_shm_unlock(size, shp->mlock_user); fput(file); no_file: ipc_rcu_putref(shp, shm_rcu_free); return error; } /* * Called with shm_ids.rwsem and ipcp locked. */ static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg) { struct shmid_kernel *shp; shp = container_of(ipcp, struct shmid_kernel, shm_perm); return security_shm_associate(shp, shmflg); } /* * Called with shm_ids.rwsem and ipcp locked. */ static inline 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; } SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg) { struct ipc_namespace *ns; struct ipc_ops shm_ops; struct ipc_params shm_params; ns = current->nsproxy->ipc_ns; shm_ops.getnew = newseg; shm_ops.associate = shm_security; shm_ops.more_checks = shm_more_checks; shm_params.key = key; shm_params.flg = shmflg; shm_params.u.size = size; return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params); } 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(&info->lock); *rss_add += inode->i_mapping->nrpages; *swp_add += info->swapped; spin_unlock(&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 shmid_ds __user *buf, int version) { struct kern_ipc_perm *ipcp; struct shmid64_ds shmid64; struct shmid_kernel *shp; int err; if (cmd == IPC_SET) { if (copy_shmid_from_user(&shmid64, buf, version)) return -EFAULT; } down_write(&shm_ids(ns).rwsem); rcu_read_lock(); ipcp = ipcctl_pre_down_nolock(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, 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 = get_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_nolock(struct ipc_namespace *ns, int shmid, int cmd, int version, void __user *buf) { int err; struct shmid_kernel *shp; /* preliminary security checks for *_INFO */ if (cmd == IPC_INFO || cmd == SHM_INFO) { err = security_shm_shmctl(NULL, cmd); if (err) return err; } switch (cmd) { case IPC_INFO: { struct shminfo64 shminfo; 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; if (copy_shminfo_to_user(buf, &shminfo, version)) return -EFAULT; down_read(&shm_ids(ns).rwsem); err = ipc_get_maxid(&shm_ids(ns)); up_read(&shm_ids(ns).rwsem); if (err < 0) err = 0; goto out; } case SHM_INFO: { struct shm_info shm_info; 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_maxid(&shm_ids(ns)); up_read(&shm_ids(ns).rwsem); if (copy_to_user(buf, &shm_info, sizeof(shm_info))) { err = -EFAULT; goto out; } err = err < 0 ? 0 : err; goto out; } case SHM_STAT: case IPC_STAT: { struct shmid64_ds tbuf; int result; rcu_read_lock(); if (cmd == SHM_STAT) { shp = shm_obtain_object(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); goto out_unlock; } result = shp->shm_perm.id; } else { shp = shm_obtain_object_check(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); goto out_unlock; } result = 0; } err = -EACCES; if (ipcperms(ns, &shp->shm_perm, S_IRUGO)) goto out_unlock; err = security_shm_shmctl(shp, cmd); if (err) goto out_unlock; memset(&tbuf, 0, sizeof(tbuf)); 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; tbuf.shm_cpid = shp->shm_cprid; tbuf.shm_lpid = shp->shm_lprid; tbuf.shm_nattch = shp->shm_nattch; rcu_read_unlock(); if (copy_shmid_to_user(buf, &tbuf, version)) err = -EFAULT; else err = result; goto out; } default: return -EINVAL; } out_unlock: rcu_read_unlock(); out: return err; } SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf) { struct shmid_kernel *shp; int err, version; struct ipc_namespace *ns; if (cmd < 0 || shmid < 0) return -EINVAL; version = ipc_parse_version(&cmd); ns = current->nsproxy->ipc_ns; switch (cmd) { case IPC_INFO: case SHM_INFO: case SHM_STAT: case IPC_STAT: return shmctl_nolock(ns, shmid, cmd, version, buf); case IPC_RMID: case IPC_SET: return shmctl_down(ns, shmid, cmd, buf, version); case SHM_LOCK: case SHM_UNLOCK: { struct file *shm_file; 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, 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 user_struct *user = current_user(); err = shmem_lock(shm_file, 1, user); if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) { shp->shm_perm.mode |= SHM_LOCKED; shp->mlock_user = user; } goto out_unlock0; } /* SHM_UNLOCK */ if (!(shp->shm_perm.mode & SHM_LOCKED)) goto out_unlock0; shmem_lock(shm_file, 0, shp->mlock_user); shp->shm_perm.mode &= ~SHM_LOCKED; shp->mlock_user = 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; } default: return -EINVAL; } out_unlock0: ipc_unlock_object(&shp->shm_perm); out_unlock1: rcu_read_unlock(); return err; } /* * 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 size; struct file *file; int err; unsigned long flags; unsigned long prot; int acc_mode; struct ipc_namespace *ns; struct shm_file_data *sfd; struct path path; fmode_t f_mode; unsigned long populate = 0; err = -EINVAL; if (shmid < 0) goto out; else if ((addr = (ulong)shmaddr)) { if (addr & (shmlba - 1)) { if (shmflg & SHM_RND) addr &= ~(shmlba - 1); /* round down */ else #ifndef __ARCH_FORCE_SHMLBA if (addr & ~PAGE_MASK) #endif goto out; } flags = MAP_SHARED | MAP_FIXED; } else { if ((shmflg & SHM_REMAP)) goto out; flags = MAP_SHARED; } if (shmflg & SHM_RDONLY) { prot = PROT_READ; acc_mode = S_IRUGO; f_mode = FMODE_READ; } else { prot = PROT_READ | PROT_WRITE; acc_mode = S_IRUGO | S_IWUGO; f_mode = FMODE_READ | FMODE_WRITE; } 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, 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; } path = shp->shm_file->f_path; path_get(&path); shp->shm_nattch++; size = i_size_read(path.dentry->d_inode); ipc_unlock_object(&shp->shm_perm); rcu_read_unlock(); err = -ENOMEM; sfd = kzalloc(sizeof(*sfd), GFP_KERNEL); if (!sfd) { path_put(&path); goto out_nattch; } file = alloc_file(&path, f_mode, is_file_hugepages(shp->shm_file) ? &shm_file_operations_huge : &shm_file_operations); err = PTR_ERR(file); if (IS_ERR(file)) { kfree(sfd); path_put(&path); goto out_nattch; } file->private_data = sfd; file->f_mapping = shp->shm_file->f_mapping; sfd->id = shp->shm_perm.id; sfd->ns = get_ipc_ns(ns); sfd->file = shp->shm_file; sfd->vm_ops = NULL; err = security_mmap_file(file, prot, flags); if (err) goto out_fput; down_write(¤t->mm->mmap_sem); if (addr && !(shmflg & SHM_REMAP)) { err = -EINVAL; if (find_vma_intersection(current->mm, addr, addr + size)) goto invalid; /* * If shm segment goes below stack, make sure there is some * space left for the stack to grow (at least 4 pages). */ if (addr < current->mm->start_stack && addr > current->mm->start_stack - size - PAGE_SIZE * 5) goto invalid; } addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate); *raddr = addr; err = 0; if (IS_ERR_VALUE(addr)) err = (long)addr; invalid: up_write(¤t->mm->mmap_sem); if (populate) mm_populate(addr, populate); out_fput: fput(file); out_nattch: down_write(&shm_ids(ns).rwsem); shp = shm_lock(ns, shmid); BUG_ON(IS_ERR(shp)); shp->shm_nattch--; if (shm_may_destroy(ns, 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; } /* * detach and kill segment if marked destroyed. * The work is done in shm_close. */ SYSCALL_DEFINE1(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 vm_area_struct *next; #endif if (addr & ~PAGE_MASK) return retval; down_write(&mm->mmap_sem); /* * 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. * 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) { size = file_inode(vma->vm_file)->i_size; do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start); /* * 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) do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start); 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); retval = 0; } #endif up_write(&mm->mmap_sem); return retval; } #ifdef CONFIG_PROC_FS static int sysvipc_shm_proc_show(struct seq_file *s, void *it) { struct user_namespace *user_ns = seq_user_ns(s); struct shmid_kernel *shp = it; unsigned long rss = 0, swp = 0; shm_add_rss_swap(shp, &rss, &swp); #if BITS_PER_LONG <= 32 #define SIZE_SPEC "%10lu" #else #define SIZE_SPEC "%21lu" #endif return seq_printf(s, "%10d %10d %4o " SIZE_SPEC " %5u %5u " "%5lu %5u %5u %5u %5u %10lu %10lu %10lu " SIZE_SPEC " " SIZE_SPEC "\n", shp->shm_perm.key, shp->shm_perm.id, shp->shm_perm.mode, shp->shm_segsz, shp->shm_cprid, shp->shm_lprid, 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); } #endif