static DEFINE_MUTEX(allocated_ptys_lock);
-static struct vfsmount *devpts_mnt;
-
struct pts_mount_opts {
int setuid;
int setgid;
kgid_t gid;
umode_t mode;
umode_t ptmxmode;
- int newinstance;
+ int reserve;
int max;
};
{Opt_uid, "uid=%u"},
{Opt_gid, "gid=%u"},
{Opt_mode, "mode=%o"},
-#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
{Opt_ptmxmode, "ptmxmode=%o"},
{Opt_newinstance, "newinstance"},
{Opt_max, "max=%d"},
-#endif
{Opt_err, NULL}
};
return sb->s_fs_info;
}
-static inline struct super_block *pts_sb_from_inode(struct inode *inode)
+struct pts_fs_info *devpts_acquire(struct file *filp)
{
-#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
- if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
- return inode->i_sb;
-#endif
- if (!devpts_mnt)
- return NULL;
- return devpts_mnt->mnt_sb;
+ struct pts_fs_info *result;
+ struct path path;
+ struct super_block *sb;
+ int err;
+
+ path = filp->f_path;
+ path_get(&path);
+
+ /* Has the devpts filesystem already been found? */
+ sb = path.mnt->mnt_sb;
+ if (sb->s_magic != DEVPTS_SUPER_MAGIC) {
+ /* Is a devpts filesystem at "pts" in the same directory? */
+ err = path_pts(&path);
+ if (err) {
+ result = ERR_PTR(err);
+ goto out;
+ }
+
+ /* Is the path the root of a devpts filesystem? */
+ result = ERR_PTR(-ENODEV);
+ sb = path.mnt->mnt_sb;
+ if ((sb->s_magic != DEVPTS_SUPER_MAGIC) ||
+ (path.mnt->mnt_root != sb->s_root))
+ goto out;
+ }
+
+ /*
+ * pty code needs to hold extra references in case of last /dev/tty close
+ */
+ atomic_inc(&sb->s_active);
+ result = DEVPTS_SB(sb);
+
+out:
+ path_put(&path);
+ return result;
+}
+
+void devpts_release(struct pts_fs_info *fsi)
+{
+ deactivate_super(fsi->sb);
}
#define PARSE_MOUNT 0
/*
* parse_mount_options():
* Set @opts to mount options specified in @data. If an option is not
- * specified in @data, set it to its default value. The exception is
- * 'newinstance' option which can only be set/cleared on a mount (i.e.
- * cannot be changed during remount).
+ * specified in @data, set it to its default value.
*
* Note: @data may be NULL (in which case all options are set to default).
*/
opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
opts->max = NR_UNIX98_PTY_MAX;
- /* newinstance makes sense only on initial mount */
+ /* Only allow instances mounted from the initial mount
+ * namespace to tap the reserve pool of ptys.
+ */
if (op == PARSE_MOUNT)
- opts->newinstance = 0;
+ opts->reserve =
+ (current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns);
while ((p = strsep(&data, ",")) != NULL) {
substring_t args[MAX_OPT_ARGS];
return -EINVAL;
opts->mode = option & S_IALLUGO;
break;
-#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
case Opt_ptmxmode:
if (match_octal(&args[0], &option))
return -EINVAL;
opts->ptmxmode = option & S_IALLUGO;
break;
case Opt_newinstance:
- /* newinstance makes sense only on initial mount */
- if (op == PARSE_MOUNT)
- opts->newinstance = 1;
break;
case Opt_max:
if (match_int(&args[0], &option) ||
return -EINVAL;
opts->max = option;
break;
-#endif
default:
pr_err("called with bogus options\n");
return -EINVAL;
return 0;
}
-#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
static int mknod_ptmx(struct super_block *sb)
{
int mode;
inode->i_mode = S_IFCHR|fsi->mount_opts.ptmxmode;
}
}
-#else
-static inline void update_ptmx_mode(struct pts_fs_info *fsi)
-{
- return;
-}
-#endif
static int devpts_remount(struct super_block *sb, int *flags, char *data)
{
seq_printf(seq, ",gid=%u",
from_kgid_munged(&init_user_ns, opts->gid));
seq_printf(seq, ",mode=%03o", opts->mode);
-#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode);
if (opts->max < NR_UNIX98_PTY_MAX)
seq_printf(seq, ",max=%d", opts->max);
-#endif
return 0;
}
return -ENOMEM;
}
-#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
-static int compare_init_pts_sb(struct super_block *s, void *p)
-{
- if (devpts_mnt)
- return devpts_mnt->mnt_sb == s;
- return 0;
-}
-
/*
* devpts_mount()
*
- * If the '-o newinstance' mount option was specified, mount a new
- * (private) instance of devpts. PTYs created in this instance are
- * independent of the PTYs in other devpts instances.
- *
- * If the '-o newinstance' option was not specified, mount/remount the
- * initial kernel mount of devpts. This type of mount gives the
- * legacy, single-instance semantics.
- *
- * The 'newinstance' option is needed to support multiple namespace
- * semantics in devpts while preserving backward compatibility of the
- * current 'single-namespace' semantics. i.e all mounts of devpts
- * without the 'newinstance' mount option should bind to the initial
- * kernel mount, like mount_single().
- *
- * Mounts with 'newinstance' option create a new, private namespace.
- *
- * NOTE:
- *
- * For single-mount semantics, devpts cannot use mount_single(),
- * because mount_single()/sget() find and use the super-block from
- * the most recent mount of devpts. But that recent mount may be a
- * 'newinstance' mount and mount_single() would pick the newinstance
- * super-block instead of the initial super-block.
+ * Mount a new (private) instance of devpts. PTYs created in this
+ * instance are independent of the PTYs in other devpts instances.
*/
static struct dentry *devpts_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
if (error)
return ERR_PTR(error);
- /* Require newinstance for all user namespace mounts to ensure
- * the mount options are not changed.
- */
- if ((current_user_ns() != &init_user_ns) && !opts.newinstance)
- return ERR_PTR(-EINVAL);
-
- if (opts.newinstance)
- s = sget(fs_type, NULL, set_anon_super, flags, NULL);
- else
- s = sget(fs_type, compare_init_pts_sb, set_anon_super, flags,
- NULL);
-
+ s = sget(fs_type, NULL, set_anon_super, flags, NULL);
if (IS_ERR(s))
return ERR_CAST(s);
return ERR_PTR(error);
}
-#else
-/*
- * This supports only the legacy single-instance semantics (no
- * multiple-instance semantics)
- */
-static struct dentry *devpts_mount(struct file_system_type *fs_type, int flags,
- const char *dev_name, void *data)
-{
- return mount_single(fs_type, flags, data, devpts_fill_super);
-}
-#endif
-
static void devpts_kill_sb(struct super_block *sb)
{
struct pts_fs_info *fsi = DEVPTS_SB(sb);
.name = "devpts",
.mount = devpts_mount,
.kill_sb = devpts_kill_sb,
-#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
.fs_flags = FS_USERNS_MOUNT | FS_USERNS_DEV_MOUNT,
-#endif
};
/*
int index;
int ida_ret;
- if (!fsi)
- return -ENODEV;
-
retry:
if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL))
return -ENOMEM;
mutex_lock(&allocated_ptys_lock);
- if (pty_count >= pty_limit -
- (fsi->mount_opts.newinstance ? pty_reserve : 0)) {
+ if (pty_count >= (pty_limit -
+ (fsi->mount_opts.reserve ? 0 : pty_reserve))) {
mutex_unlock(&allocated_ptys_lock);
return -ENOSPC;
}
mutex_unlock(&allocated_ptys_lock);
}
-/*
- * pty code needs to hold extra references in case of last /dev/tty close
- */
-struct pts_fs_info *devpts_get_ref(struct inode *ptmx_inode, struct file *file)
-{
- struct super_block *sb;
- struct pts_fs_info *fsi;
-
- sb = pts_sb_from_inode(ptmx_inode);
- if (!sb)
- return NULL;
- fsi = DEVPTS_SB(sb);
- if (!fsi)
- return NULL;
-
- atomic_inc(&sb->s_active);
- return fsi;
-}
-
-void devpts_put_ref(struct pts_fs_info *fsi)
-{
- deactivate_super(fsi->sb);
-}
-
/**
* devpts_pty_new -- create a new inode in /dev/pts/
* @ptmx_inode: inode of the master
struct dentry *devpts_pty_new(struct pts_fs_info *fsi, int index, void *priv)
{
struct dentry *dentry;
- struct super_block *sb;
+ struct super_block *sb = fsi->sb;
struct inode *inode;
struct dentry *root;
struct pts_mount_opts *opts;
char s[12];
- if (!fsi)
- return ERR_PTR(-ENODEV);
-
- sb = fsi->sb;
root = sb->s_root;
opts = &fsi->mount_opts;
static int __init init_devpts_fs(void)
{
int err = register_filesystem(&devpts_fs_type);
- struct ctl_table_header *table;
-
if (!err) {
- struct vfsmount *mnt;
-
- table = register_sysctl_table(pty_root_table);
- mnt = kern_mount(&devpts_fs_type);
- if (IS_ERR(mnt)) {
- err = PTR_ERR(mnt);
- unregister_filesystem(&devpts_fs_type);
- unregister_sysctl_table(table);
- } else {
- devpts_mnt = mnt;
- }
+ register_sysctl_table(pty_root_table);
}
return err;
}
projects / cascardo / linux.git / blobdiff