/* * 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 #include #include #include #include #include #include #include "util.h" #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(shp) ipc_unlock(&(shp)->shm_perm) #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, NULL, 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); } static inline void shm_inc (int id) { struct shmid_kernel *shp; if(!(shp = shm_lock(id))) BUG(); shp->shm_atim = get_seconds(); shp->shm_lprid = current->tgid; shp->shm_nattch++; shm_unlock(shp); } /* 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, * but returns with shp unlocked and freed. */ static void shm_destroy (struct shmid_kernel *shp) { shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT; shm_rmid (shp->id); 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_dentry->d_inode->i_size, shp->mlock_user); fput (shp->shm_file); security_shm_free(shp); ipc_rcu_putref(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->tgid; shp->shm_dtim = get_seconds(); shp->shm_nattch--; if(shp->shm_nattch == 0 && shp->shm_flags & SHM_DEST) shm_destroy (shp); else shm_unlock(shp); up (&shm_ids.sem); } static int shm_mmap(struct file * file, struct vm_area_struct * vma) { file_accessed(file); 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, #ifdef CONFIG_NUMA .set_policy = shmem_set_policy, .get_policy = shmem_get_policy, #endif }; 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 = ipc_rcu_alloc(sizeof(*shp)); if (!shp) return -ENOMEM; shp->shm_perm.key = key; shp->shm_flags = (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; } if (shmflg & SHM_HUGETLB) { /* hugetlb_zero_setup takes care of mlock user accounting */ file = hugetlb_zero_setup(size); shp->mlock_user = current->user; } else { sprintf (name, "SYSV%08x", key); file = shmem_file_setup(name, size, VM_ACCOUNT); } 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_cprid = current->tgid; 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->id = shm_buildid(id,shp->shm_perm.seq); shp->shm_file = file; file->f_dentry->d_inode->i_ino = shp->id; if (shmflg & SHM_HUGETLB) set_file_hugepages(file); else file->f_op = &shm_file_operations; shm_tot += numpages; shm_unlock(shp); return shp->id; no_id: fput(file); no_file: security_shm_free(shp); ipc_rcu_putref(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 { int shmid = shm_buildid(id, shp->shm_perm.seq); err = security_shm_associate(shp, shmflg); if (!err) err = shmid; } shm_unlock(shp); } up(&shm_ids.sem); return err; } 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_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 __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; } } static void shm_get_stat(unsigned long *rss, unsigned long *swp) { 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) continue; inode = shp->shm_file->f_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); } } } asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf) { struct shm_setbuf setbuf; struct shmid_kernel *shp; int err, version; if (cmd < 0 || shmid < 0) { err = -EINVAL; goto out; } version = ipc_parse_version(&cmd); 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 = 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; 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(&shm_ids.sem); 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; up(&shm_ids.sem); 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; memset(&tbuf, 0, sizeof(tbuf)); shp = shm_lock(shmid); if(shp==NULL) { err = -EINVAL; goto out; } else 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; err = security_shm_shmctl(shp, cmd); if (err) 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; if (!is_file_hugepages(shp->shm_file)) tbuf.shm_nattch = shp->shm_nattch; else tbuf.shm_nattch = file_count(shp->shm_file) - 1; 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(shmid); if(shp==NULL) { err = -EINVAL; goto out; } err = shm_checkid(shp,shmid); 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_flags |= 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_flags &= ~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(&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; } err = security_shm_shmctl(shp, cmd); if (err) 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; shm_unlock(shp); } else shm_destroy (shp); up(&shm_ids.sem); goto out; } case IPC_SET: { if (copy_shmid_from_user (&setbuf, buf, version)) { err = -EFAULT; goto out; } if ((err = audit_ipc_perms(0, setbuf.uid, setbuf.gid, setbuf.mode))) return err; 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; } 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_flags = (shp->shm_flags & ~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(&shm_ids.sem); 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; unsigned long o_flags; int acc_mode; void *user_addr; if (shmid < 0) { err = -EINVAL; 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 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; } 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... */ shp = shm_lock(shmid); if(shp == NULL) { err = -EINVAL; goto out; } err = shm_checkid(shp,shmid); if (err) { shm_unlock(shp); goto out; } if (ipcperms(&shp->shm_perm, acc_mode)) { shm_unlock(shp); err = -EACCES; goto out; } err = security_shm_shmat(shp, shmaddr, shmflg); if (err) { shm_unlock(shp); return err; } file = shp->shm_file; size = i_size_read(file->f_dentry->d_inode); shp->shm_nattch++; shm_unlock(shp); 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); else shm_unlock(shp); up (&shm_ids.sem); *raddr = (unsigned long) user_addr; err = 0; if (IS_ERR(user_addr)) err = PTR_ERR(user_addr); out: return err; } 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; 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 || is_vm_hugetlb_page(vma)) && (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) { size = vma->vm_file->f_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. */ 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 || is_vm_hugetlb_page(vma)) && (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_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, is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : 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(shp); 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