/* * 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 * BIGMEM support, Andrea Arcangeli * SMP thread shm, Jean-Luc Boyard * HIGHMEM support, Ingo Molnar * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland * Shared /dev/zero support, Kanoj Sarcar * Move the mm functionality over to mm/shmem.c, Christoph Rohland * */ #include #include #include #include #include #include #include #include #include "util.h" struct shmid_kernel /* private to the kernel */ { struct kern_ipc_perm shm_perm; struct file * shm_file; int id; unsigned long shm_nattch; unsigned long shm_segsz; time_t shm_atim; time_t shm_dtim; time_t shm_ctim; pid_t shm_cprid; pid_t shm_lprid; }; #define shm_flags shm_perm.mode static struct file_operations shm_file_operations; static struct vm_operations_struct shm_vm_ops; static struct ipc_ids shm_ids; #define shm_lock(id) ((struct shmid_kernel*)ipc_lock(&shm_ids,id)) #define shm_unlock(id) ipc_unlock(&shm_ids,id) #define shm_lockall() ipc_lockall(&shm_ids) #define shm_unlockall() ipc_unlockall(&shm_ids) #define shm_get(id) ((struct shmid_kernel*)ipc_get(&shm_ids,id)) #define shm_buildid(id, seq) \ ipc_buildid(&shm_ids, id, seq) static int newseg (key_t key, int shmflg, size_t size); static void shm_open (struct vm_area_struct *shmd); static void shm_close (struct vm_area_struct *shmd); #ifdef CONFIG_PROC_FS static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data); #endif size_t shm_ctlmax = SHMMAX; size_t shm_ctlall = SHMALL; int shm_ctlmni = SHMMNI; static int shm_tot; /* total number of shared memory pages */ void __init shm_init (void) { ipc_init_ids(&shm_ids, 1); #ifdef CONFIG_PROC_FS create_proc_read_entry("sysvipc/shm", 0, 0, sysvipc_shm_read_proc, NULL); #endif } static inline int shm_checkid(struct shmid_kernel *s, int id) { if (ipc_checkid(&shm_ids,&s->shm_perm,id)) return -EIDRM; return 0; } static inline struct shmid_kernel *shm_rmid(int id) { return (struct shmid_kernel *)ipc_rmid(&shm_ids,id); } static inline int shm_addid(struct shmid_kernel *shp) { return ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni+1); } static inline void shm_inc (int id) { struct shmid_kernel *shp; if(!(shp = shm_lock(id))) BUG(); shp->shm_atim = CURRENT_TIME; shp->shm_lprid = current->pid; shp->shm_nattch++; shm_unlock(id); } /* This is called by fork, once for every shm attach. */ static void shm_open (struct vm_area_struct *shmd) { shm_inc (shmd->vm_file->f_dentry->d_inode->i_ino); } /* * shm_destroy - free the struct shmid_kernel * * @shp: struct to free * * It has to be called with shp and shm_ids.sem locked */ static void shm_destroy (struct shmid_kernel *shp) { shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT; shm_rmid (shp->id); shmem_lock(shp->shm_file, 0); fput (shp->shm_file); kfree (shp); } /* * remove the attach descriptor shmd. * 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 *shmd) { struct file * file = shmd->vm_file; int id = file->f_dentry->d_inode->i_ino; struct shmid_kernel *shp; down (&shm_ids.sem); /* remove from the list of attaches of the shm segment */ if(!(shp = shm_lock(id))) BUG(); shp->shm_lprid = current->pid; shp->shm_dtim = CURRENT_TIME; shp->shm_nattch--; if(shp->shm_nattch == 0 && shp->shm_flags & SHM_DEST) shm_destroy (shp); shm_unlock(id); up (&shm_ids.sem); } static int shm_mmap(struct file * file, struct vm_area_struct * vma) { UPDATE_ATIME(file->f_dentry->d_inode); vma->vm_ops = &shm_vm_ops; shm_inc(file->f_dentry->d_inode->i_ino); return 0; } static struct file_operations shm_file_operations = { mmap: shm_mmap }; 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 */ nopage: shmem_nopage, }; static int newseg (key_t key, int shmflg, size_t 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 > shm_ctlmax) return -EINVAL; if (shm_tot + numpages >= shm_ctlall) return -ENOSPC; shp = (struct shmid_kernel *) kmalloc (sizeof (*shp), GFP_USER); if (!shp) return -ENOMEM; sprintf (name, "SYSV%08x", key); file = shmem_file_setup(name, size); error = PTR_ERR(file); if (IS_ERR(file)) goto no_file; error = -ENOSPC; id = shm_addid(shp); if(id == -1) goto no_id; shp->shm_perm.key = key; shp->shm_flags = (shmflg & S_IRWXUGO); shp->shm_cprid = current->pid; shp->shm_lprid = 0; shp->shm_atim = shp->shm_dtim = 0; shp->shm_ctim = CURRENT_TIME; shp->shm_segsz = size; shp->shm_nattch = 0; shp->id = shm_buildid(id,shp->shm_perm.seq); shp->shm_file = file; file->f_dentry->d_inode->i_ino = shp->id; file->f_op = &shm_file_operations; shm_tot += numpages; shm_unlock (id); return shp->id; no_id: fput(file); no_file: kfree(shp); return error; } asmlinkage long sys_shmget (key_t key, size_t size, int shmflg) { struct shmid_kernel *shp; int err, id = 0; down(&shm_ids.sem); if (key == IPC_PRIVATE) { err = newseg(key, shmflg, size); } else if ((id = ipc_findkey(&shm_ids, key)) == -1) { if (!(shmflg & IPC_CREAT)) err = -ENOENT; else err = newseg(key, shmflg, size); } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) { err = -EEXIST; } else { shp = shm_lock(id); if(shp==NULL) BUG(); if (shp->shm_segsz < size) err = -EINVAL; else if (ipcperms(&shp->shm_perm, shmflg)) err = -EACCES; else err = shm_buildid(id, shp->shm_perm.seq); shm_unlock(id); } up(&shm_ids.sem); return err; } static inline unsigned long copy_shmid_to_user(void *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 *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_flags; 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_flags; return 0; } default: return -EINVAL; } } static inline unsigned long copy_shminfo_to_user(void *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; } } static void shm_get_stat (unsigned long *rss, unsigned long *swp) { struct shmem_inode_info *info; int i; *rss = 0; *swp = 0; for(i = 0; i <= shm_ids.max_id; i++) { struct shmid_kernel* shp; struct inode * inode; shp = shm_get(i); if(shp == NULL) continue; inode = shp->shm_file->f_dentry->d_inode; info = SHMEM_I(inode); spin_lock (&info->lock); *rss += inode->i_mapping->nrpages; *swp += info->swapped; spin_unlock (&info->lock); } } asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds *buf) { struct shm_setbuf setbuf; struct shmid_kernel *shp; int err, version; if (cmd < 0 || shmid < 0) return -EINVAL; version = ipc_parse_version(&cmd); switch (cmd) { /* replace with proc interface ? */ case IPC_INFO: { struct shminfo64 shminfo; memset(&shminfo,0,sizeof(shminfo)); shminfo.shmmni = shminfo.shmseg = shm_ctlmni; shminfo.shmmax = shm_ctlmax; shminfo.shmall = shm_ctlall; shminfo.shmmin = SHMMIN; if(copy_shminfo_to_user (buf, &shminfo, version)) return -EFAULT; /* reading a integer is always atomic */ err= shm_ids.max_id; if(err<0) err = 0; return err; } case SHM_INFO: { struct shm_info shm_info; memset(&shm_info,0,sizeof(shm_info)); down(&shm_ids.sem); shm_lockall(); shm_info.used_ids = shm_ids.in_use; shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp); shm_info.shm_tot = shm_tot; shm_info.swap_attempts = 0; shm_info.swap_successes = 0; err = shm_ids.max_id; shm_unlockall(); up(&shm_ids.sem); if(copy_to_user (buf, &shm_info, sizeof(shm_info))) return -EFAULT; return err < 0 ? 0 : err; } case SHM_STAT: case IPC_STAT: { struct shmid64_ds tbuf; int result; memset(&tbuf, 0, sizeof(tbuf)); shp = shm_lock(shmid); if(shp==NULL) return -EINVAL; if(cmd==SHM_STAT) { err = -EINVAL; if (shmid > shm_ids.max_id) goto out_unlock; result = shm_buildid(shmid, shp->shm_perm.seq); } else { err = shm_checkid(shp,shmid); if(err) goto out_unlock; result = 0; } err=-EACCES; if (ipcperms (&shp->shm_perm, S_IRUGO)) 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; tbuf.shm_cpid = shp->shm_cprid; tbuf.shm_lpid = shp->shm_lprid; tbuf.shm_nattch = shp->shm_nattch; shm_unlock(shmid); if(copy_shmid_to_user (buf, &tbuf, version)) return -EFAULT; return result; } case SHM_LOCK: case SHM_UNLOCK: { /* Allow superuser to lock segment in memory */ /* Should the pages be faulted in here or leave it to user? */ /* need to determine interaction with current->swappable */ if (!capable(CAP_IPC_LOCK)) return -EPERM; shp = shm_lock(shmid); if(shp==NULL) return -EINVAL; err = shm_checkid(shp,shmid); if(err) goto out_unlock; if(cmd==SHM_LOCK) { shmem_lock(shp->shm_file, 1); shp->shm_flags |= SHM_LOCKED; } else { shmem_lock(shp->shm_file, 0); shp->shm_flags &= ~SHM_LOCKED; } shm_unlock(shmid); return err; } 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(&shm_ids.sem); shp = shm_lock(shmid); err = -EINVAL; if (shp == NULL) goto out_up; err = shm_checkid(shp, shmid); 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; } if (shp->shm_nattch){ shp->shm_flags |= SHM_DEST; /* Do not find it any more */ shp->shm_perm.key = IPC_PRIVATE; } else shm_destroy (shp); /* Unlock */ shm_unlock(shmid); up(&shm_ids.sem); return err; } case IPC_SET: { if(copy_shmid_from_user (&setbuf, buf, version)) return -EFAULT; down(&shm_ids.sem); shp = shm_lock(shmid); err=-EINVAL; if(shp==NULL) goto out_up; err = shm_checkid(shp,shmid); 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; } shp->shm_perm.uid = setbuf.uid; shp->shm_perm.gid = setbuf.gid; shp->shm_flags = (shp->shm_flags & ~S_IRWXUGO) | (setbuf.mode & S_IRWXUGO); shp->shm_ctim = CURRENT_TIME; break; } default: return -EINVAL; } err = 0; out_unlock_up: shm_unlock(shmid); out_up: up(&shm_ids.sem); return err; out_unlock: shm_unlock(shmid); return err; } /* * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists. */ asmlinkage long sys_shmat (int shmid, char *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; unsigned long o_flags; int acc_mode; void *user_addr; if (shmid < 0) return -EINVAL; if ((addr = (ulong)shmaddr)) { if (addr & (SHMLBA-1)) { if (shmflg & SHM_RND) addr &= ~(SHMLBA-1); /* round down */ else return -EINVAL; } flags = MAP_SHARED | MAP_FIXED; } else { if ((shmflg & SHM_REMAP)) return -EINVAL; flags = MAP_SHARED; } if (shmflg & SHM_RDONLY) { prot = PROT_READ; o_flags = O_RDONLY; acc_mode = S_IRUGO; } else { prot = PROT_READ | PROT_WRITE; o_flags = O_RDWR; acc_mode = S_IRUGO | S_IWUGO; } /* * We cannot rely on the fs check since SYSV IPC does have an * additional creator id... */ shp = shm_lock(shmid); if(shp == NULL) return -EINVAL; err = shm_checkid(shp,shmid); if (err) { shm_unlock(shmid); return err; } if (ipcperms(&shp->shm_perm, acc_mode)) { shm_unlock(shmid); return -EACCES; } file = shp->shm_file; size = file->f_dentry->d_inode->i_size; shp->shm_nattch++; shm_unlock(shmid); down_write(¤t->mm->mmap_sem); if (addr && !(shmflg & SHM_REMAP)) { user_addr = ERR_PTR(-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 = (void*) do_mmap (file, addr, size, prot, flags, 0); invalid: up_write(¤t->mm->mmap_sem); down (&shm_ids.sem); if(!(shp = shm_lock(shmid))) BUG(); shp->shm_nattch--; if(shp->shm_nattch == 0 && shp->shm_flags & SHM_DEST) shm_destroy (shp); shm_unlock(shmid); up (&shm_ids.sem); *raddr = (unsigned long) user_addr; err = 0; if (IS_ERR(user_addr)) err = PTR_ERR(user_addr); return err; } /* * detach and kill segment if marked destroyed. * The work is done in shm_close. */ asmlinkage long sys_shmdt (char *shmaddr) { struct mm_struct *mm = current->mm; struct vm_area_struct *shmd, *shmdnext; int retval = -EINVAL; down_write(&mm->mmap_sem); for (shmd = mm->mmap; shmd; shmd = shmdnext) { shmdnext = shmd->vm_next; if (shmd->vm_ops == &shm_vm_ops && shmd->vm_start - (shmd->vm_pgoff << PAGE_SHIFT) == (ulong) shmaddr) do_munmap(mm, shmd->vm_start, shmd->vm_end - shmd->vm_start); retval = 0; } up_write(&mm->mmap_sem); return retval; } #ifdef CONFIG_PROC_FS static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data) { off_t pos = 0; off_t begin = 0; int i, len = 0; down(&shm_ids.sem); len += sprintf(buffer, " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime\n"); for(i = 0; i <= shm_ids.max_id; i++) { struct shmid_kernel* shp; shp = shm_lock(i); if(shp!=NULL) { #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" char *format; if (sizeof(size_t) <= sizeof(int)) format = SMALL_STRING; else format = BIG_STRING; len += sprintf(buffer + len, format, shp->shm_perm.key, shm_buildid(i, shp->shm_perm.seq), shp->shm_flags, 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); shm_unlock(i); pos += len; if(pos < offset) { len = 0; begin = pos; } if(pos > offset + length) goto done; } } *eof = 1; done: up(&shm_ids.sem); *start = buffer + (offset - begin); len -= (offset - begin); if(len > length) len = length; if(len < 0) len = 0; return len; } #endif