Merge branch 'work.mqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
authorLinus Torvalds <torvalds@linux-foundation.org>
Wed, 31 Jan 2018 02:32:21 +0000 (18:32 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 31 Jan 2018 02:32:21 +0000 (18:32 -0800)
Pull mqueue/bpf vfs cleanups from Al Viro:
 "mqueue and bpf go through rather painful and similar contortions to
  create objects in their dentry trees. Provide a primitive for doing
  that without abusing ->mknod(), switch bpf and mqueue to it.

  Another mqueue-related thing that has ended up in that branch is
  on-demand creation of internal mount (based upon the work of Giuseppe
  Scrivano)"

* 'work.mqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  mqueue: switch to on-demand creation of internal mount
  tidy do_mq_open() up a bit
  mqueue: clean prepare_open() up
  do_mq_open(): move all work prior to dentry_open() into a helper
  mqueue: fold mq_attr_ok() into mqueue_get_inode()
  move dentry_open() calls up into do_mq_open()
  mqueue: switch to vfs_mkobj(), quit abusing ->d_fsdata
  bpf_obj_do_pin(): switch to vfs_mkobj(), quit abusing ->mknod()
  new primitive: vfs_mkobj()

fs/namei.c
include/linux/fs.h
ipc/mqueue.c
kernel/bpf/inode.c

index 4e3fc58dae7227fbb24ce97b1d4404df31ec9445..7c221fb0836bc5fa2022e512d56892e14387b361 100644 (file)
@@ -2895,6 +2895,27 @@ int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 }
 EXPORT_SYMBOL(vfs_create);
 
+int vfs_mkobj(struct dentry *dentry, umode_t mode,
+               int (*f)(struct dentry *, umode_t, void *),
+               void *arg)
+{
+       struct inode *dir = dentry->d_parent->d_inode;
+       int error = may_create(dir, dentry);
+       if (error)
+               return error;
+
+       mode &= S_IALLUGO;
+       mode |= S_IFREG;
+       error = security_inode_create(dir, dentry, mode);
+       if (error)
+               return error;
+       error = f(dentry, mode, arg);
+       if (!error)
+               fsnotify_create(dir, dentry);
+       return error;
+}
+EXPORT_SYMBOL(vfs_mkobj);
+
 bool may_open_dev(const struct path *path)
 {
        return !(path->mnt->mnt_flags & MNT_NODEV) &&
index 569c51d37312a31ba9f7bd74e3d0575b4b9ba849..9798a133e7185b9a78a58c12ce36226a9224298d 100644 (file)
@@ -1608,6 +1608,10 @@ extern int vfs_whiteout(struct inode *, struct dentry *);
 extern struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode,
                                  int open_flag);
 
+int vfs_mkobj(struct dentry *, umode_t,
+               int (*f)(struct dentry *, umode_t, void *),
+               void *);
+
 /*
  * VFS file helper functions.
  */
index 3bc5bb7d68274ed3eddfd5d1c0b71dcf7ce7200b..690ae6665500f7990e29f44cc662d590b491147f 100644 (file)
@@ -270,13 +270,30 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
                 * that means the min(mq_maxmsg, max_priorities) * struct
                 * posix_msg_tree_node.
                 */
+
+               ret = -EINVAL;
+               if (info->attr.mq_maxmsg <= 0 || info->attr.mq_msgsize <= 0)
+                       goto out_inode;
+               if (capable(CAP_SYS_RESOURCE)) {
+                       if (info->attr.mq_maxmsg > HARD_MSGMAX ||
+                           info->attr.mq_msgsize > HARD_MSGSIZEMAX)
+                               goto out_inode;
+               } else {
+                       if (info->attr.mq_maxmsg > ipc_ns->mq_msg_max ||
+                                       info->attr.mq_msgsize > ipc_ns->mq_msgsize_max)
+                               goto out_inode;
+               }
+               ret = -EOVERFLOW;
+               /* check for overflow */
+               if (info->attr.mq_msgsize > ULONG_MAX/info->attr.mq_maxmsg)
+                       goto out_inode;
                mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
                        min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
                        sizeof(struct posix_msg_tree_node);
-
-               mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
-                                         info->attr.mq_msgsize);
-
+               mq_bytes = info->attr.mq_maxmsg * info->attr.mq_msgsize;
+               if (mq_bytes + mq_treesize < mq_bytes)
+                       goto out_inode;
+               mq_bytes += mq_treesize;
                spin_lock(&mq_lock);
                if (u->mq_bytes + mq_bytes < u->mq_bytes ||
                    u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
@@ -308,8 +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;
@@ -326,18 +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)
@@ -416,11 +460,11 @@ static void mqueue_evict_inode(struct inode *inode)
                put_ipc_ns(ipc_ns);
 }
 
-static int mqueue_create(struct inode *dir, struct dentry *dentry,
-                               umode_t mode, bool excl)
+static int mqueue_create_attr(struct dentry *dentry, umode_t mode, void *arg)
 {
+       struct inode *dir = dentry->d_parent->d_inode;
        struct inode *inode;
-       struct mq_attr *attr = dentry->d_fsdata;
+       struct mq_attr *attr = arg;
        int error;
        struct ipc_namespace *ipc_ns;
 
@@ -461,6 +505,12 @@ out_unlock:
        return error;
 }
 
+static int mqueue_create(struct inode *dir, struct dentry *dentry,
+                               umode_t mode, bool excl)
+{
+       return mqueue_create_attr(dentry, mode, NULL);
+}
+
 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
 {
        struct inode *inode = d_inode(dentry);
@@ -691,96 +741,46 @@ static void remove_notification(struct mqueue_inode_info *info)
        info->notify_user_ns = NULL;
 }
 
-static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
-{
-       int mq_treesize;
-       unsigned long total_size;
-
-       if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
-               return -EINVAL;
-       if (capable(CAP_SYS_RESOURCE)) {
-               if (attr->mq_maxmsg > HARD_MSGMAX ||
-                   attr->mq_msgsize > HARD_MSGSIZEMAX)
-                       return -EINVAL;
-       } else {
-               if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
-                               attr->mq_msgsize > ipc_ns->mq_msgsize_max)
-                       return -EINVAL;
-       }
-       /* check for overflow */
-       if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
-               return -EOVERFLOW;
-       mq_treesize = attr->mq_maxmsg * sizeof(struct msg_msg) +
-               min_t(unsigned int, attr->mq_maxmsg, MQ_PRIO_MAX) *
-               sizeof(struct posix_msg_tree_node);
-       total_size = attr->mq_maxmsg * attr->mq_msgsize;
-       if (total_size + mq_treesize < total_size)
-               return -EOVERFLOW;
-       return 0;
-}
-
-/*
- * Invoked when creating a new queue via sys_mq_open
- */
-static struct file *do_create(struct ipc_namespace *ipc_ns, struct inode *dir,
-                       struct path *path, int oflag, umode_t mode,
+static int prepare_open(struct dentry *dentry, int oflag, int ro,
+                       umode_t mode, struct filename *name,
                        struct mq_attr *attr)
-{
-       const struct cred *cred = current_cred();
-       int ret;
-
-       if (attr) {
-               ret = mq_attr_ok(ipc_ns, attr);
-               if (ret)
-                       return ERR_PTR(ret);
-               /* store for use during create */
-               path->dentry->d_fsdata = attr;
-       } else {
-               struct mq_attr def_attr;
-
-               def_attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
-                                        ipc_ns->mq_msg_default);
-               def_attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
-                                         ipc_ns->mq_msgsize_default);
-               ret = mq_attr_ok(ipc_ns, &def_attr);
-               if (ret)
-                       return ERR_PTR(ret);
-       }
-
-       mode &= ~current_umask();
-       ret = vfs_create(dir, path->dentry, mode, true);
-       path->dentry->d_fsdata = NULL;
-       if (ret)
-               return ERR_PTR(ret);
-       return dentry_open(path, oflag, cred);
-}
-
-/* Opens existing queue */
-static struct file *do_open(struct path *path, int oflag)
 {
        static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
                                                  MAY_READ | MAY_WRITE };
        int acc;
+
+       if (d_really_is_negative(dentry)) {
+               if (!(oflag & O_CREAT))
+                       return -ENOENT;
+               if (ro)
+                       return ro;
+               audit_inode_parent_hidden(name, dentry->d_parent);
+               return vfs_mkobj(dentry, mode & ~current_umask(),
+                                 mqueue_create_attr, attr);
+       }
+       /* it already existed */
+       audit_inode(name, dentry, 0);
+       if ((oflag & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
+               return -EEXIST;
        if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
-               return ERR_PTR(-EINVAL);
+               return -EINVAL;
        acc = oflag2acc[oflag & O_ACCMODE];
-       if (inode_permission(d_inode(path->dentry), acc))
-               return ERR_PTR(-EACCES);
-       return dentry_open(path, oflag, current_cred());
+       return inode_permission(d_inode(dentry), acc);
 }
 
 static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
                      struct mq_attr *attr)
 {
-       struct path path;
-       struct file *filp;
+       struct vfsmount *mnt = mq_internal_mount();
+       struct dentry *root;
        struct filename *name;
+       struct path path;
        int fd, error;
-       struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
-       struct vfsmount *mnt = ipc_ns->mq_mnt;
-       struct dentry *root = mnt->mnt_root;
        int ro;
 
+       if (IS_ERR(mnt))
+               return PTR_ERR(mnt);
+
        audit_mq_open(oflag, mode, attr);
 
        if (IS_ERR(name = getname(u_name)))
@@ -791,7 +791,7 @@ 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 */
-       error = 0;
+       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)) {
@@ -799,38 +799,14 @@ static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
                goto out_putfd;
        }
        path.mnt = mntget(mnt);
-
-       if (oflag & O_CREAT) {
-               if (d_really_is_positive(path.dentry)) {        /* entry already exists */
-                       audit_inode(name, path.dentry, 0);
-                       if (oflag & O_EXCL) {
-                               error = -EEXIST;
-                               goto out;
-                       }
-                       filp = do_open(&path, oflag);
-               } else {
-                       if (ro) {
-                               error = ro;
-                               goto out;
-                       }
-                       audit_inode_parent_hidden(name, root);
-                       filp = do_create(ipc_ns, d_inode(root), &path,
-                                        oflag, mode, attr);
-               }
-       } else {
-               if (d_really_is_negative(path.dentry)) {
-                       error = -ENOENT;
-                       goto out;
-               }
-               audit_inode(name, path.dentry, 0);
-               filp = do_open(&path, oflag);
+       error = prepare_open(path.dentry, oflag, ro, mode, name, attr);
+       if (!error) {
+               struct file *file = dentry_open(&path, oflag, current_cred());
+               if (!IS_ERR(file))
+                       fd_install(fd, file);
+               else
+                       error = PTR_ERR(file);
        }
-
-       if (!IS_ERR(filp))
-               fd_install(fd, filp);
-       else
-               error = PTR_ERR(filp);
-out:
        path_put(&path);
 out_putfd:
        if (error) {
@@ -864,6 +840,9 @@ 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);
@@ -1590,28 +1569,26 @@ 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",
@@ -1633,6 +1610,10 @@ 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:
index 5bb5e49ef4c3831050cf9fa92278a150fde40bfa..81e2f6995adb14ea7e99e2a5cf6c27203ed726ef 100644 (file)
@@ -150,39 +150,29 @@ static int bpf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
        return 0;
 }
 
-static int bpf_mkobj_ops(struct inode *dir, struct dentry *dentry,
-                        umode_t mode, const struct inode_operations *iops)
+static int bpf_mkobj_ops(struct dentry *dentry, umode_t mode, void *raw,
+                        const struct inode_operations *iops)
 {
-       struct inode *inode;
-
-       inode = bpf_get_inode(dir->i_sb, dir, mode | S_IFREG);
+       struct inode *dir = dentry->d_parent->d_inode;
+       struct inode *inode = bpf_get_inode(dir->i_sb, dir, mode);
        if (IS_ERR(inode))
                return PTR_ERR(inode);
 
        inode->i_op = iops;
-       inode->i_private = dentry->d_fsdata;
+       inode->i_private = raw;
 
        bpf_dentry_finalize(dentry, inode, dir);
        return 0;
 }
 
-static int bpf_mkobj(struct inode *dir, struct dentry *dentry, umode_t mode,
-                    dev_t devt)
+static int bpf_mkprog(struct dentry *dentry, umode_t mode, void *arg)
 {
-       enum bpf_type type = MINOR(devt);
-
-       if (MAJOR(devt) != UNNAMED_MAJOR || !S_ISREG(mode) ||
-           dentry->d_fsdata == NULL)
-               return -EPERM;
+       return bpf_mkobj_ops(dentry, mode, arg, &bpf_prog_iops);
+}
 
-       switch (type) {
-       case BPF_TYPE_PROG:
-               return bpf_mkobj_ops(dir, dentry, mode, &bpf_prog_iops);
-       case BPF_TYPE_MAP:
-               return bpf_mkobj_ops(dir, dentry, mode, &bpf_map_iops);
-       default:
-               return -EPERM;
-       }
+static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg)
+{
+       return bpf_mkobj_ops(dentry, mode, arg, &bpf_map_iops);
 }
 
 static struct dentry *
@@ -218,7 +208,6 @@ static int bpf_symlink(struct inode *dir, struct dentry *dentry,
 
 static const struct inode_operations bpf_dir_iops = {
        .lookup         = bpf_lookup,
-       .mknod          = bpf_mkobj,
        .mkdir          = bpf_mkdir,
        .symlink        = bpf_symlink,
        .rmdir          = simple_rmdir,
@@ -234,7 +223,6 @@ static int bpf_obj_do_pin(const struct filename *pathname, void *raw,
        struct inode *dir;
        struct path path;
        umode_t mode;
-       dev_t devt;
        int ret;
 
        dentry = kern_path_create(AT_FDCWD, pathname->name, &path, 0);
@@ -242,9 +230,8 @@ static int bpf_obj_do_pin(const struct filename *pathname, void *raw,
                return PTR_ERR(dentry);
 
        mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask());
-       devt = MKDEV(UNNAMED_MAJOR, type);
 
-       ret = security_path_mknod(&path, dentry, mode, devt);
+       ret = security_path_mknod(&path, dentry, mode, 0);
        if (ret)
                goto out;
 
@@ -254,9 +241,16 @@ static int bpf_obj_do_pin(const struct filename *pathname, void *raw,
                goto out;
        }
 
-       dentry->d_fsdata = raw;
-       ret = vfs_mknod(dir, dentry, mode, devt);
-       dentry->d_fsdata = NULL;
+       switch (type) {
+       case BPF_TYPE_PROG:
+               ret = vfs_mkobj(dentry, mode, bpf_mkprog, raw);
+               break;
+       case BPF_TYPE_MAP:
+               ret = vfs_mkobj(dentry, mode, bpf_mkmap, raw);
+               break;
+       default:
+               ret = -EPERM;
+       }
 out:
        done_path_create(&path, dentry);
        return ret;