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-rw-r--r--ipc/shm.c917
1 files changed, 917 insertions, 0 deletions
diff --git a/ipc/shm.c b/ipc/shm.c
new file mode 100644
index 000000000000..06cd5c91056f
--- /dev/null
+++ b/ipc/shm.c
@@ -0,0 +1,917 @@
+/*
+ * 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>
+ *
+ */
+
+#include <linux/config.h>
+#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/proc_fs.h>
+#include <linux/shmem_fs.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/audit.h>
+#include <asm/uaccess.h>
+
+#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(&current->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(&current->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;
+}
+
+/*
+ * 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

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