/* * 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> */ #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 <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 struct vm_operations_struct shm_vm_ops; static struct ipc_ids init_shm_ids; #define shm_ids(ns) (*((ns)->ids[IPC_SHM_IDS])) #define shm_unlock(shp) \ ipc_unlock(&(shp)->shm_perm) #define shm_buildid(id, seq) ipc_buildid(id, seq) 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 static void __shm_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids) { ns->ids[IPC_SHM_IDS] = ids; ns->shm_ctlmax = SHMMAX; ns->shm_ctlall = SHMALL; ns->shm_ctlmni = SHMMNI; ns->shm_tot = 0; ipc_init_ids(ids); } /* * Called with shm_ids.rw_mutex (writer) and the shp structure locked. * Only shm_ids.rw_mutex remains locked on exit. */ static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp) { 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); } int shm_init_ns(struct ipc_namespace *ns) { struct ipc_ids *ids; ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL); if (ids == NULL) return -ENOMEM; __shm_init_ns(ns, ids); return 0; } void shm_exit_ns(struct ipc_namespace *ns) { struct shmid_kernel *shp; struct kern_ipc_perm *perm; int next_id; int total, in_use; down_write(&shm_ids(ns).rw_mutex); in_use = shm_ids(ns).in_use; for (total = 0, next_id = 0; total < in_use; next_id++) { perm = idr_find(&shm_ids(ns).ipcs_idr, next_id); if (perm == NULL) continue; ipc_lock_by_ptr(perm); shp = container_of(perm, struct shmid_kernel, shm_perm); do_shm_rmid(ns, shp); total++; } up_write(&shm_ids(ns).rw_mutex); kfree(ns->ids[IPC_SHM_IDS]); ns->ids[IPC_SHM_IDS] = NULL; } void __init shm_init (void) { __shm_init_ns(&init_ipc_ns, &init_shm_ids); ipc_init_proc_interface("sysvipc/shm", " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime\n", IPC_SHM_IDS, sysvipc_shm_proc_show); } /* * shm_lock_(check_)down routines are called in the paths where the rw_mutex * is held to protect access to the idr tree. */ static inline struct shmid_kernel *shm_lock_down(struct ipc_namespace *ns, int id) { struct kern_ipc_perm *ipcp = ipc_lock_down(&shm_ids(ns), id); if (IS_ERR(ipcp)) return (struct shmid_kernel *)ipcp; return container_of(ipcp, struct shmid_kernel, shm_perm); } static inline struct shmid_kernel *shm_lock_check_down( struct ipc_namespace *ns, int id) { struct kern_ipc_perm *ipcp = ipc_lock_check_down(&shm_ids(ns), id); if (IS_ERR(ipcp)) return (struct shmid_kernel *)ipcp; return container_of(ipcp, struct shmid_kernel, shm_perm); } /* * shm_lock_(check_) routines are called in the paths where the rw_mutex * is not 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 struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns, int id) { struct kern_ipc_perm *ipcp = ipc_lock_check(&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_rmid(struct ipc_namespace *ns, struct shmid_kernel *s) { ipc_rmid(&shm_ids(ns), &s->shm_perm); } static inline int shm_addid(struct ipc_namespace *ns, struct shmid_kernel *shp) { return ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni); } /* 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.rw_mutex (writer) locked, * but returns with shp unlocked and freed. */ static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp) { ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT; shm_rmid(ns, shp); shm_unlock(shp); if (!is_file_hugepages(shp->shm_file)) shmem_lock(shp->shm_file, 0, shp->mlock_user); else user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size, shp->mlock_user); fput (shp->shm_file); security_shm_free(shp); ipc_rcu_putref(shp); } /* * 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).rw_mutex); /* remove from the list of attaches of the shm segment */ shp = shm_lock_down(ns, sfd->id); BUG_ON(IS_ERR(shp)); shp->shm_lprid = task_tgid_vnr(current); shp->shm_dtim = get_seconds(); shp->shm_nattch--; if(shp->shm_nattch == 0 && shp->shm_perm.mode & SHM_DEST) shm_destroy(ns, shp); else shm_unlock(shp); up_write(&shm_ids(ns).rw_mutex); } 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; else pol = current->mempolicy; 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, struct dentry *dentry, int datasync) { int (*fsync) (struct file *, struct dentry *, int datasync); struct shm_file_data *sfd = shm_file_data(file); int ret = -EINVAL; fsync = sfd->file->f_op->fsync; if (fsync) ret = fsync(sfd->file, sfd->file->f_path.dentry, datasync); return ret; } 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 get_unmapped_area(sfd->file, addr, len, pgoff, flags); } int is_file_shm_hugepages(struct file *file) { int ret = 0; if (file->f_op == &shm_file_operations) { struct shm_file_data *sfd; sfd = shm_file_data(file); ret = is_file_hugepages(sfd->file); } return ret; } static const struct file_operations shm_file_operations = { .mmap = shm_mmap, .fsync = shm_fsync, .release = shm_release, .get_unmapped_area = shm_get_unmapped_area, }; static 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.rw_mutex 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; int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT; struct file * file; char name[13]; int id; 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); return error; } sprintf (name, "SYSV%08x", key); if (shmflg & SHM_HUGETLB) { /* hugetlb_file_setup takes care of mlock user accounting */ file = hugetlb_file_setup(name, size); shp->mlock_user = current->user; } else { int acctflag = VM_ACCOUNT; /* * Do not allow no accounting for OVERCOMMIT_NEVER, even * if it's asked for. */ if ((shmflg & SHM_NORESERVE) && sysctl_overcommit_memory != OVERCOMMIT_NEVER) acctflag = 0; file = shmem_file_setup(name, size, acctflag); } error = PTR_ERR(file); if (IS_ERR(file)) goto no_file; id = shm_addid(ns, shp); 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_perm.id = shm_buildid(id, shp->shm_perm.seq); shp->shm_file = file; /* * shmid gets reported as "inode#" in /proc/pid/maps. * proc-ps tools use this. Changing this will break them. */ file->f_dentry->d_inode->i_ino = shp->shm_perm.id; ns->shm_tot += numpages; error = shp->shm_perm.id; shm_unlock(shp); return error; no_id: fput(file); no_file: security_shm_free(shp); ipc_rcu_putref(shp); return error; } /* * Called with shm_ids.rw_mutex 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.rw_mutex 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; } asmlinkage long sys_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; 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; } } struct shm_setbuf { uid_t uid; gid_t gid; mode_t mode; }; static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version) { switch(version) { case IPC_64: { struct shmid64_ds tbuf; if (copy_from_user(&tbuf, buf, sizeof(tbuf))) return -EFAULT; out->uid = tbuf.shm_perm.uid; out->gid = tbuf.shm_perm.gid; out->mode = tbuf.shm_perm.mode; return 0; } case IPC_OLD: { struct shmid_ds tbuf_old; if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) return -EFAULT; out->uid = tbuf_old.shm_perm.uid; out->gid = tbuf_old.shm_perm.gid; out->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; } } /* * Called with shm_ids.rw_mutex 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 shmid_kernel *shp; struct inode *inode; shp = idr_find(&shm_ids(ns).ipcs_idr, next_id); if (shp == NULL) continue; inode = shp->shm_file->f_path.dentry->d_inode; if (is_file_hugepages(shp->shm_file)) { struct address_space *mapping = inode->i_mapping; *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages; } else { struct shmem_inode_info *info = SHMEM_I(inode); spin_lock(&info->lock); *rss += inode->i_mapping->nrpages; *swp += info->swapped; spin_unlock(&info->lock); } total++; } } asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf) { struct shm_setbuf setbuf; struct shmid_kernel *shp; int err, version; struct ipc_namespace *ns; if (cmd < 0 || shmid < 0) { err = -EINVAL; goto out; } version = ipc_parse_version(&cmd); ns = current->nsproxy->ipc_ns; switch (cmd) { /* replace with proc interface ? */ case IPC_INFO: { struct shminfo64 shminfo; err = security_shm_shmctl(NULL, cmd); if (err) return 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; if(copy_shminfo_to_user (buf, &shminfo, version)) return -EFAULT; down_read(&shm_ids(ns).rw_mutex); err = ipc_get_maxid(&shm_ids(ns)); up_read(&shm_ids(ns).rw_mutex); if(err<0) err = 0; goto out; } case SHM_INFO: { struct shm_info shm_info; err = security_shm_shmctl(NULL, cmd); if (err) return err; memset(&shm_info,0,sizeof(shm_info)); down_read(&shm_ids(ns).rw_mutex); 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).rw_mutex); 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; if (!buf) { err = -EFAULT; goto out; } if (cmd == SHM_STAT) { shp = shm_lock(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); goto out; } result = shp->shm_perm.id; } else { shp = shm_lock_check(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); goto out; } result = 0; } err=-EACCES; if (ipcperms (&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; shm_unlock(shp); if(copy_shmid_to_user (buf, &tbuf, version)) err = -EFAULT; else err = result; goto out; } case SHM_LOCK: case SHM_UNLOCK: { shp = shm_lock_check(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); goto out; } err = audit_ipc_obj(&(shp->shm_perm)); if (err) goto out_unlock; if (!capable(CAP_IPC_LOCK)) { err = -EPERM; if (current->euid != shp->shm_perm.uid && current->euid != shp->shm_perm.cuid) goto out_unlock; if (cmd == SHM_LOCK && !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur) goto out_unlock; } err = security_shm_shmctl(shp, cmd); if (err) goto out_unlock; if(cmd==SHM_LOCK) { struct user_struct * user = current->user; if (!is_file_hugepages(shp->shm_file)) { err = shmem_lock(shp->shm_file, 1, user); if (!err && !(shp->shm_perm.mode & SHM_LOCKED)){ shp->shm_perm.mode |= SHM_LOCKED; shp->mlock_user = user; } } } else if (!is_file_hugepages(shp->shm_file)) { shmem_lock(shp->shm_file, 0, shp->mlock_user); shp->shm_perm.mode &= ~SHM_LOCKED; shp->mlock_user = NULL; } shm_unlock(shp); goto out; } case IPC_RMID: { /* * We cannot simply remove the file. The SVID states * that the block remains until the last person * detaches from it, then is deleted. A shmat() on * an RMID segment is legal in older Linux and if * we change it apps break... * * Instead we set a destroyed flag, and then blow * the name away when the usage hits zero. */ down_write(&shm_ids(ns).rw_mutex); shp = shm_lock_check_down(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); goto out_up; } err = audit_ipc_obj(&(shp->shm_perm)); if (err) goto out_unlock_up; if (current->euid != shp->shm_perm.uid && current->euid != shp->shm_perm.cuid && !capable(CAP_SYS_ADMIN)) { err=-EPERM; goto out_unlock_up; } err = security_shm_shmctl(shp, cmd); if (err) goto out_unlock_up; do_shm_rmid(ns, shp); up_write(&shm_ids(ns).rw_mutex); goto out; } case IPC_SET: { if (!buf) { err = -EFAULT; goto out; } if (copy_shmid_from_user (&setbuf, buf, version)) { err = -EFAULT; goto out; } down_write(&shm_ids(ns).rw_mutex); shp = shm_lock_check_down(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); goto out_up; } err = audit_ipc_obj(&(shp->shm_perm)); if (err) goto out_unlock_up; err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode); if (err) goto out_unlock_up; err=-EPERM; if (current->euid != shp->shm_perm.uid && current->euid != shp->shm_perm.cuid && !capable(CAP_SYS_ADMIN)) { goto out_unlock_up; } err = security_shm_shmctl(shp, cmd); if (err) goto out_unlock_up; shp->shm_perm.uid = setbuf.uid; shp->shm_perm.gid = setbuf.gid; shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO) | (setbuf.mode & S_IRWXUGO); shp->shm_ctim = get_seconds(); break; } default: err = -EINVAL; goto out; } err = 0; out_unlock_up: shm_unlock(shp); out_up: up_write(&shm_ids(ns).rw_mutex); goto out; out_unlock: shm_unlock(shp); out: 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) { struct shmid_kernel *shp; unsigned long addr; unsigned long size; struct file * file; int err; unsigned long flags; unsigned long prot; int acc_mode; unsigned long user_addr; struct ipc_namespace *ns; struct shm_file_data *sfd; struct path path; mode_t f_mode; 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; shp = shm_lock_check(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); goto out; } err = -EACCES; if (ipcperms(&shp->shm_perm, acc_mode)) goto out_unlock; err = security_shm_shmat(shp, shmaddr, shmflg); if (err) goto out_unlock; path.dentry = dget(shp->shm_file->f_path.dentry); path.mnt = shp->shm_file->f_path.mnt; shp->shm_nattch++; size = i_size_read(path.dentry->d_inode); shm_unlock(shp); err = -ENOMEM; sfd = kzalloc(sizeof(*sfd), GFP_KERNEL); if (!sfd) goto out_put_dentry; err = -ENOMEM; file = alloc_file(path.mnt, path.dentry, f_mode, &shm_file_operations); if (!file) goto out_free; 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; 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; } user_addr = do_mmap (file, addr, size, prot, flags, 0); *raddr = user_addr; err = 0; if (IS_ERR_VALUE(user_addr)) err = (long)user_addr; invalid: up_write(¤t->mm->mmap_sem); fput(file); out_nattch: down_write(&shm_ids(ns).rw_mutex); shp = shm_lock_down(ns, shmid); BUG_ON(IS_ERR(shp)); shp->shm_nattch--; if(shp->shm_nattch == 0 && shp->shm_perm.mode & SHM_DEST) shm_destroy(ns, shp); else shm_unlock(shp); up_write(&shm_ids(ns).rw_mutex); out: return err; out_unlock: shm_unlock(shp); goto out; out_free: kfree(sfd); out_put_dentry: dput(path.dentry); goto out_nattch; } asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg) { unsigned long ret; long err; err = do_shmat(shmid, shmaddr, shmflg, &ret); 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. */ asmlinkage long sys_shmdt(char __user *shmaddr) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma, *next; unsigned long addr = (unsigned long)shmaddr; loff_t size = 0; int retval = -EINVAL; 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); 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 = vma->vm_file->f_path.dentry->d_inode->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 comparisions 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; } up_write(&mm->mmap_sem); return retval; } #ifdef CONFIG_PROC_FS static int sysvipc_shm_proc_show(struct seq_file *s, void *it) { struct shmid_kernel *shp = it; char *format; #define SMALL_STRING "%10d %10d %4o %10u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n" #define BIG_STRING "%10d %10d %4o %21u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n" if (sizeof(size_t) <= sizeof(int)) format = SMALL_STRING; else format = BIG_STRING; return seq_printf(s, format, shp->shm_perm.key, shp->shm_perm.id, shp->shm_perm.mode, shp->shm_segsz, shp->shm_cprid, shp->shm_lprid, shp->shm_nattch, shp->shm_perm.uid, shp->shm_perm.gid, shp->shm_perm.cuid, shp->shm_perm.cgid, shp->shm_atim, shp->shm_dtim, shp->shm_ctim); } #endif