#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/namei.h>
+#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/tty.h>
#include <linux/mutex.h>
+#include <linux/magic.h>
#include <linux/idr.h>
#include <linux/devpts_fs.h>
#include <linux/parser.h>
#include <linux/fsnotify.h>
#include <linux/seq_file.h>
-#define DEVPTS_SUPER_MAGIC 0x1cd1
-
#define DEVPTS_DEFAULT_MODE 0600
+/*
+ * ptmx is a new node in /dev/pts and will be unused in legacy (single-
+ * instance) mode. To prevent surprises in user space, set permissions of
+ * ptmx to 0. Use 'chmod' or remount with '-o ptmxmode' to set meaningful
+ * permissions.
+ */
+#define DEVPTS_DEFAULT_PTMX_MODE 0000
#define PTMX_MINOR 2
extern int pty_limit; /* Config limit on Unix98 ptys */
uid_t uid;
gid_t gid;
umode_t mode;
+ umode_t ptmxmode;
+ int newinstance;
};
enum {
- Opt_uid, Opt_gid, Opt_mode,
+ Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance,
Opt_err
};
{Opt_uid, "uid=%u"},
{Opt_gid, "gid=%u"},
{Opt_mode, "mode=%o"},
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+ {Opt_ptmxmode, "ptmxmode=%o"},
+ {Opt_newinstance, "newinstance"},
+#endif
{Opt_err, NULL}
};
struct pts_fs_info {
struct ida allocated_ptys;
struct pts_mount_opts mount_opts;
+ struct dentry *ptmx_dentry;
};
static inline struct pts_fs_info *DEVPTS_SB(struct super_block *sb)
static inline struct super_block *pts_sb_from_inode(struct inode *inode)
{
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
return inode->i_sb;
-
+#endif
return devpts_mnt->mnt_sb;
}
-static int devpts_remount(struct super_block *sb, int *flags, char *data)
+#define PARSE_MOUNT 0
+#define PARSE_REMOUNT 1
+
+/*
+ * 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).
+ *
+ * Note: @data may be NULL (in which case all options are set to default).
+ */
+static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts)
{
char *p;
- struct pts_fs_info *fsi = DEVPTS_SB(sb);
- struct pts_mount_opts *opts = &fsi->mount_opts;
opts->setuid = 0;
opts->setgid = 0;
opts->uid = 0;
opts->gid = 0;
opts->mode = DEVPTS_DEFAULT_MODE;
+ opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
+
+ /* newinstance makes sense only on initial mount */
+ if (op == PARSE_MOUNT)
+ opts->newinstance = 0;
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;
+#endif
default:
printk(KERN_ERR "devpts: called with bogus options\n");
return -EINVAL;
return 0;
}
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+static int mknod_ptmx(struct super_block *sb)
+{
+ int mode;
+ int rc = -ENOMEM;
+ struct dentry *dentry;
+ struct inode *inode;
+ struct dentry *root = sb->s_root;
+ struct pts_fs_info *fsi = DEVPTS_SB(sb);
+ struct pts_mount_opts *opts = &fsi->mount_opts;
+
+ mutex_lock(&root->d_inode->i_mutex);
+
+ /* If we have already created ptmx node, return */
+ if (fsi->ptmx_dentry) {
+ rc = 0;
+ goto out;
+ }
+
+ dentry = d_alloc_name(root, "ptmx");
+ if (!dentry) {
+ printk(KERN_NOTICE "Unable to alloc dentry for ptmx node\n");
+ goto out;
+ }
+
+ /*
+ * Create a new 'ptmx' node in this mount of devpts.
+ */
+ inode = new_inode(sb);
+ if (!inode) {
+ printk(KERN_ERR "Unable to alloc inode for ptmx node\n");
+ dput(dentry);
+ goto out;
+ }
+
+ inode->i_ino = 2;
+ inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+
+ mode = S_IFCHR|opts->ptmxmode;
+ init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
+
+ d_add(dentry, inode);
+
+ fsi->ptmx_dentry = dentry;
+ rc = 0;
+out:
+ mutex_unlock(&root->d_inode->i_mutex);
+ return rc;
+}
+
+static void update_ptmx_mode(struct pts_fs_info *fsi)
+{
+ struct inode *inode;
+ if (fsi->ptmx_dentry) {
+ inode = fsi->ptmx_dentry->d_inode;
+ 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)
+{
+ int err;
+ struct pts_fs_info *fsi = DEVPTS_SB(sb);
+ struct pts_mount_opts *opts = &fsi->mount_opts;
+
+ err = parse_mount_options(data, PARSE_REMOUNT, opts);
+
+ /*
+ * parse_mount_options() restores options to default values
+ * before parsing and may have changed ptmxmode. So, update the
+ * mode in the inode too. Bogus options don't fail the remount,
+ * so do this even on error return.
+ */
+ update_ptmx_mode(fsi);
+
+ return err;
+}
+
static int devpts_show_options(struct seq_file *seq, struct vfsmount *vfs)
{
struct pts_fs_info *fsi = DEVPTS_SB(vfs->mnt_sb);
if (opts->setgid)
seq_printf(seq, ",gid=%u", opts->gid);
seq_printf(seq, ",mode=%03o", opts->mode);
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+ seq_printf(seq, ",ptmxmode=%03o", opts->ptmxmode);
+#endif
return 0;
}
ida_init(&fsi->allocated_ptys);
fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE;
+ fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE;
return fsi;
}
static int
devpts_fill_super(struct super_block *s, void *data, int silent)
{
- struct inode * inode;
+ struct inode *inode;
s->s_blocksize = 1024;
s->s_blocksize_bits = 10;
goto free_fsi;
inode->i_ino = 1;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
- inode->i_blocks = 0;
- inode->i_uid = inode->i_gid = 0;
inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
s->s_root = d_alloc_root(inode);
if (s->s_root)
return 0;
-
- printk("devpts: get root dentry failed\n");
+
+ printk(KERN_ERR "devpts: get root dentry failed\n");
iput(inode);
free_fsi:
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_get_sb()
+ *
+ * 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 get_sb_single().
+ *
+ * Mounts with 'newinstance' option create a new, private namespace.
+ *
+ * NOTE:
+ *
+ * For single-mount semantics, devpts cannot use get_sb_single(),
+ * because get_sb_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 get_sb_single() would pick the newinstance
+ * super-block instead of the initial super-block.
+ */
static int devpts_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
+ int error;
+ struct pts_mount_opts opts;
+ struct super_block *s;
+
+ error = parse_mount_options(data, PARSE_MOUNT, &opts);
+ if (error)
+ return error;
+
+ if (opts.newinstance)
+ s = sget(fs_type, NULL, set_anon_super, NULL);
+ else
+ s = sget(fs_type, compare_init_pts_sb, set_anon_super, NULL);
+
+ if (IS_ERR(s))
+ return PTR_ERR(s);
+
+ if (!s->s_root) {
+ s->s_flags = flags;
+ error = devpts_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
+ if (error)
+ goto out_undo_sget;
+ s->s_flags |= MS_ACTIVE;
+ }
+
+ memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts));
+
+ error = mknod_ptmx(s);
+ if (error)
+ goto out_undo_sget;
+
+ simple_set_mnt(mnt, s);
+
+ return 0;
+
+out_undo_sget:
+ deactivate_locked_super(s);
+ return error;
+}
+
+#else
+/*
+ * This supports only the legacy single-instance semantics (no
+ * multiple-instance semantics)
+ */
+static int devpts_get_sb(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *data, struct vfsmount *mnt)
+{
return get_sb_single(fs_type, flags, data, devpts_fill_super, mnt);
}
+#endif
static void devpts_kill_sb(struct super_block *sb)
{
struct pts_fs_info *fsi = DEVPTS_SB(sb);
kfree(fsi);
- kill_anon_super(sb);
+ kill_litter_super(sb);
}
static struct file_system_type devpts_fs_type = {
- .owner = THIS_MODULE,
.name = "devpts",
.get_sb = devpts_get_sb,
.kill_sb = devpts_kill_sb,
int ida_ret;
retry:
- if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) {
+ if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL))
return -ENOMEM;
- }
mutex_lock(&allocated_ptys_lock);
ida_ret = ida_get_new(&fsi->allocated_ptys, &index);
int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
{
- int number = tty->index; /* tty layer puts index from devpts_new_index() in here */
+ /* tty layer puts index from devpts_new_index() in here */
+ int number = tty->index;
struct tty_driver *driver = tty->driver;
dev_t device = MKDEV(driver->major, driver->minor_start+number);
struct dentry *dentry;
if (!inode)
return -ENOMEM;
- inode->i_ino = number+2;
- inode->i_uid = config.setuid ? config.uid : current_fsuid();
- inode->i_gid = config.setgid ? config.gid : current_fsgid();
+ inode->i_ino = number + 3;
+ inode->i_uid = opts->setuid ? opts->uid : current_fsuid();
+ inode->i_gid = opts->setgid ? opts->gid : current_fsgid();
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
init_special_inode(inode, S_IFCHR|opts->mode, device);
inode->i_private = tty;
struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
{
+ struct dentry *dentry;
+ struct tty_struct *tty;
+
BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
+ /* Ensure dentry has not been deleted by devpts_pty_kill() */
+ dentry = d_find_alias(pts_inode);
+ if (!dentry)
+ return NULL;
+
+ tty = NULL;
if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
- return (struct tty_struct *)pts_inode->i_private;
- return NULL;
+ tty = (struct tty_struct *)pts_inode->i_private;
+
+ dput(dentry);
+
+ return tty;
}
void devpts_pty_kill(struct tty_struct *tty)
mutex_lock(&root->d_inode->i_mutex);
dentry = d_find_alias(inode);
- if (dentry && !IS_ERR(dentry)) {
+ if (IS_ERR(dentry))
+ goto out;
+
+ if (dentry) {
inode->i_nlink--;
d_delete(dentry);
- dput(dentry);
+ dput(dentry); /* d_alloc_name() in devpts_pty_new() */
}
+ dput(dentry); /* d_find_alias above */
+out:
mutex_unlock(&root->d_inode->i_mutex);
}
int err = register_filesystem(&devpts_fs_type);
if (!err) {
devpts_mnt = kern_mount(&devpts_fs_type);
- if (IS_ERR(devpts_mnt))
+ if (IS_ERR(devpts_mnt)) {
err = PTR_ERR(devpts_mnt);
+ unregister_filesystem(&devpts_fs_type);
+ }
}
return err;
}
-
-static void __exit exit_devpts_fs(void)
-{
- unregister_filesystem(&devpts_fs_type);
- mntput(devpts_mnt);
-}
-
module_init(init_devpts_fs)
-module_exit(exit_devpts_fs)
-MODULE_LICENSE("GPL");
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff