diff options
| -rw-r--r-- | ipc/mqueue.c | 74 |
1 files changed, 55 insertions, 19 deletions
diff --git a/ipc/mqueue.c b/ipc/mqueue.c index 9f05837a86a6..738579191fd2 100644 --- a/ipc/mqueue.c +++ b/ipc/mqueue.c @@ -325,8 +325,9 @@ err: static int mqueue_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode; - struct ipc_namespace *ns = sb->s_fs_info; + struct ipc_namespace *ns = data; + sb->s_fs_info = ns; sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV; sb->s_blocksize = PAGE_SIZE; sb->s_blocksize_bits = PAGE_SHIFT; @@ -343,18 +344,44 @@ static int mqueue_fill_super(struct super_block *sb, void *data, int silent) return 0; } +static struct file_system_type mqueue_fs_type; +/* + * Return value is pinned only by reference in ->mq_mnt; it will + * live until ipcns dies. Caller does not need to drop it. + */ +static struct vfsmount *mq_internal_mount(void) +{ + struct ipc_namespace *ns = current->nsproxy->ipc_ns; + struct vfsmount *m = ns->mq_mnt; + if (m) + return m; + m = kern_mount_data(&mqueue_fs_type, ns); + spin_lock(&mq_lock); + if (unlikely(ns->mq_mnt)) { + spin_unlock(&mq_lock); + if (!IS_ERR(m)) + kern_unmount(m); + return ns->mq_mnt; + } + if (!IS_ERR(m)) + ns->mq_mnt = m; + spin_unlock(&mq_lock); + return m; +} + static struct dentry *mqueue_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { - struct ipc_namespace *ns; - if (flags & SB_KERNMOUNT) { - ns = data; - data = NULL; - } else { - ns = current->nsproxy->ipc_ns; - } - return mount_ns(fs_type, flags, data, ns, ns->user_ns, mqueue_fill_super); + struct vfsmount *m; + if (flags & SB_KERNMOUNT) + return mount_nodev(fs_type, flags, data, mqueue_fill_super); + m = mq_internal_mount(); + if (IS_ERR(m)) + return ERR_CAST(m); + atomic_inc(&m->mnt_sb->s_active); + down_write(&m->mnt_sb->s_umount); + return dget(m->mnt_root); } static void init_once(void *foo) @@ -743,13 +770,16 @@ static int prepare_open(struct dentry *dentry, int oflag, int ro, static int do_mq_open(const char __user *u_name, int oflag, umode_t mode, struct mq_attr *attr) { - struct vfsmount *mnt = current->nsproxy->ipc_ns->mq_mnt; - struct dentry *root = mnt->mnt_root; + struct vfsmount *mnt = mq_internal_mount(); + struct dentry *root; struct filename *name; struct path path; int fd, error; int ro; + if (IS_ERR(mnt)) + return PTR_ERR(mnt); + audit_mq_open(oflag, mode, attr); if (IS_ERR(name = getname(u_name))) @@ -760,6 +790,7 @@ static int do_mq_open(const char __user *u_name, int oflag, umode_t mode, goto out_putname; ro = mnt_want_write(mnt); /* we'll drop it in any case */ + root = mnt->mnt_root; inode_lock(d_inode(root)); path.dentry = lookup_one_len(name->name, root, strlen(name->name)); if (IS_ERR(path.dentry)) { @@ -808,6 +839,9 @@ SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name) struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; struct vfsmount *mnt = ipc_ns->mq_mnt; + if (!mnt) + return -ENOENT; + name = getname(u_name); if (IS_ERR(name)) return PTR_ERR(name); @@ -1534,28 +1568,26 @@ int mq_init_ns(struct ipc_namespace *ns) ns->mq_msgsize_max = DFLT_MSGSIZEMAX; ns->mq_msg_default = DFLT_MSG; ns->mq_msgsize_default = DFLT_MSGSIZE; + ns->mq_mnt = NULL; - ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns); - if (IS_ERR(ns->mq_mnt)) { - int err = PTR_ERR(ns->mq_mnt); - ns->mq_mnt = NULL; - return err; - } return 0; } void mq_clear_sbinfo(struct ipc_namespace *ns) { - ns->mq_mnt->mnt_sb->s_fs_info = NULL; + if (ns->mq_mnt) + ns->mq_mnt->mnt_sb->s_fs_info = NULL; } void mq_put_mnt(struct ipc_namespace *ns) { - kern_unmount(ns->mq_mnt); + if (ns->mq_mnt) + kern_unmount(ns->mq_mnt); } static int __init init_mqueue_fs(void) { + struct vfsmount *m; int error; mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", @@ -1577,6 +1609,10 @@ static int __init init_mqueue_fs(void) if (error) goto out_filesystem; + m = kern_mount_data(&mqueue_fs_type, &init_ipc_ns); + if (IS_ERR(m)) + goto out_filesystem; + init_ipc_ns.mq_mnt = m; return 0; out_filesystem: |