#include <linux/namei.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 */
+static DEFINE_MUTEX(allocated_ptys_lock);
static struct vfsmount *devpts_mnt;
-static struct dentry *devpts_root;
-static struct {
+struct pts_mount_opts {
int setuid;
int setgid;
uid_t uid;
gid_t gid;
umode_t mode;
-} config = {.mode = 0600};
+ umode_t ptmxmode;
+ int newinstance;
+};
-static int devpts_remount(struct super_block *sb, int *flags, char *data)
+enum {
+ Opt_uid, Opt_gid, Opt_mode, Opt_ptmxmode, Opt_newinstance,
+ Opt_err
+};
+
+static const match_table_t tokens = {
+ {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)
+{
+ return sb->s_fs_info;
+}
+
+static inline struct super_block *pts_sb_from_inode(struct inode *inode)
{
- int setuid = 0;
- int setgid = 0;
- uid_t uid = 0;
- gid_t gid = 0;
- umode_t mode = 0600;
- char *this_char;
-
- this_char = NULL;
- while ((this_char = strsep(&data, ",")) != NULL) {
- int n;
- char dummy;
- if (!*this_char)
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+ if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
+ return inode->i_sb;
+#endif
+ return devpts_mnt->mnt_sb;
+}
+
+#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;
+
+ 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];
+ int token;
+ int option;
+
+ if (!*p)
continue;
- if (sscanf(this_char, "uid=%i%c", &n, &dummy) == 1) {
- setuid = 1;
- uid = n;
- } else if (sscanf(this_char, "gid=%i%c", &n, &dummy) == 1) {
- setgid = 1;
- gid = n;
- } else if (sscanf(this_char, "mode=%o%c", &n, &dummy) == 1)
- mode = n & ~S_IFMT;
- else {
- printk("devpts: called with bogus options\n");
+
+ token = match_token(p, tokens, args);
+ switch (token) {
+ case Opt_uid:
+ if (match_int(&args[0], &option))
+ return -EINVAL;
+ opts->uid = option;
+ opts->setuid = 1;
+ break;
+ case Opt_gid:
+ if (match_int(&args[0], &option))
+ return -EINVAL;
+ opts->gid = option;
+ opts->setgid = 1;
+ break;
+ case Opt_mode:
+ if (match_octal(&args[0], &option))
+ 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;
}
}
- config.setuid = setuid;
- config.setgid = setgid;
- config.uid = uid;
- config.gid = gid;
- config.mode = mode;
return 0;
}
-static struct super_operations devpts_sops = {
+#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);
+ struct pts_mount_opts *opts = &fsi->mount_opts;
+
+ if (opts->setuid)
+ seq_printf(seq, ",uid=%u", opts->uid);
+ 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;
+}
+
+static const struct super_operations devpts_sops = {
.statfs = simple_statfs,
.remount_fs = devpts_remount,
+ .show_options = devpts_show_options,
};
+static void *new_pts_fs_info(void)
+{
+ struct pts_fs_info *fsi;
+
+ fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL);
+ if (!fsi)
+ return NULL;
+
+ 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;
s->s_op = &devpts_sops;
s->s_time_gran = 1;
+ s->s_fs_info = new_pts_fs_info();
+ if (!s->s_fs_info)
+ goto fail;
+
inode = new_inode(s);
if (!inode)
- goto fail;
+ goto free_fsi;
inode->i_ino = 1;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
- inode->i_blocks = 0;
- inode->i_blksize = 1024;
- 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;
inode->i_nlink = 2;
- devpts_root = s->s_root = d_alloc_root(inode);
+ 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:
+ kfree(s->s_fs_info);
fail:
return -ENOMEM;
}
-static struct super_block *devpts_get_sb(struct file_system_type *fs_type,
- int flags, const char *dev_name, void *data)
+#ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES
+static int compare_init_pts_sb(struct super_block *s, void *p)
{
- return get_sb_single(fs_type, flags, data, devpts_fill_super);
+ 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;
+ }
+
+ simple_set_mnt(mnt, s);
+
+ memcpy(&(DEVPTS_SB(s))->mount_opts, &opts, sizeof(opts));
+
+ error = mknod_ptmx(s);
+ if (error)
+ goto out_dput;
+
+ return 0;
+
+out_dput:
+ dput(s->s_root); /* undo dget() in simple_set_mnt() */
+
+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_litter_super(sb);
}
static struct file_system_type devpts_fs_type = {
- .owner = THIS_MODULE,
.name = "devpts",
.get_sb = devpts_get_sb,
- .kill_sb = kill_anon_super,
+ .kill_sb = devpts_kill_sb,
};
/*
* to the System V naming convention
*/
-static struct dentry *get_node(int num)
+int devpts_new_index(struct inode *ptmx_inode)
{
- char s[12];
- struct dentry *root = devpts_root;
- mutex_lock(&root->d_inode->i_mutex);
- return lookup_one_len(s, root, sprintf(s, "%d", num));
+ struct super_block *sb = pts_sb_from_inode(ptmx_inode);
+ struct pts_fs_info *fsi = DEVPTS_SB(sb);
+ int index;
+ int ida_ret;
+
+retry:
+ 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);
+ if (ida_ret < 0) {
+ mutex_unlock(&allocated_ptys_lock);
+ if (ida_ret == -EAGAIN)
+ goto retry;
+ return -EIO;
+ }
+
+ if (index >= pty_limit) {
+ ida_remove(&fsi->allocated_ptys, index);
+ mutex_unlock(&allocated_ptys_lock);
+ return -EIO;
+ }
+ mutex_unlock(&allocated_ptys_lock);
+ return index;
+}
+
+void devpts_kill_index(struct inode *ptmx_inode, int idx)
+{
+ struct super_block *sb = pts_sb_from_inode(ptmx_inode);
+ struct pts_fs_info *fsi = DEVPTS_SB(sb);
+
+ mutex_lock(&allocated_ptys_lock);
+ ida_remove(&fsi->allocated_ptys, idx);
+ mutex_unlock(&allocated_ptys_lock);
}
-int devpts_pty_new(struct tty_struct *tty)
+int devpts_pty_new(struct inode *ptmx_inode, struct tty_struct *tty)
{
+ /* 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;
- struct inode *inode = new_inode(devpts_mnt->mnt_sb);
+ struct super_block *sb = pts_sb_from_inode(ptmx_inode);
+ struct inode *inode = new_inode(sb);
+ struct dentry *root = sb->s_root;
+ struct pts_fs_info *fsi = DEVPTS_SB(sb);
+ struct pts_mount_opts *opts = &fsi->mount_opts;
+ char s[12];
/* We're supposed to be given the slave end of a pty */
BUG_ON(driver->type != TTY_DRIVER_TYPE_PTY);
if (!inode)
return -ENOMEM;
- inode->i_ino = number+2;
- inode->i_blksize = 1024;
- 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|config.mode, device);
- inode->u.generic_ip = tty;
+ init_special_inode(inode, S_IFCHR|opts->mode, device);
+ inode->i_private = tty;
+ tty->driver_data = inode;
- dentry = get_node(number);
- if (!IS_ERR(dentry) && !dentry->d_inode)
- d_instantiate(dentry, inode);
+ sprintf(s, "%d", number);
- mutex_unlock(&devpts_root->d_inode->i_mutex);
+ mutex_lock(&root->d_inode->i_mutex);
+
+ dentry = d_alloc_name(root, s);
+ if (!IS_ERR(dentry)) {
+ d_add(dentry, inode);
+ fsnotify_create(root->d_inode, dentry);
+ }
+
+ mutex_unlock(&root->d_inode->i_mutex);
return 0;
}
-struct tty_struct *devpts_get_tty(int number)
+struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number)
{
- struct dentry *dentry = get_node(number);
- struct tty_struct *tty;
+ BUG_ON(pts_inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
- tty = NULL;
- if (!IS_ERR(dentry)) {
- if (dentry->d_inode)
- tty = dentry->d_inode->u.generic_ip;
- dput(dentry);
- }
-
- mutex_unlock(&devpts_root->d_inode->i_mutex);
-
- return tty;
+ if (pts_inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
+ return (struct tty_struct *)pts_inode->i_private;
+ return NULL;
}
-void devpts_pty_kill(int number)
+void devpts_pty_kill(struct tty_struct *tty)
{
- struct dentry *dentry = get_node(number);
+ struct inode *inode = tty->driver_data;
+ struct super_block *sb = pts_sb_from_inode(inode);
+ struct dentry *root = sb->s_root;
+ struct dentry *dentry;
- if (!IS_ERR(dentry)) {
- struct inode *inode = dentry->d_inode;
- if (inode) {
- inode->i_nlink--;
- d_delete(dentry);
- dput(dentry);
- }
- dput(dentry);
+ BUG_ON(inode->i_rdev == MKDEV(TTYAUX_MAJOR, PTMX_MINOR));
+
+ mutex_lock(&root->d_inode->i_mutex);
+
+ dentry = d_find_alias(inode);
+ if (IS_ERR(dentry))
+ goto out;
+
+ if (dentry) {
+ inode->i_nlink--;
+ d_delete(dentry);
+ dput(dentry); /* d_alloc_name() in devpts_pty_new() */
}
- mutex_unlock(&devpts_root->d_inode->i_mutex);
+
+ dput(dentry); /* d_find_alias above */
+out:
+ mutex_unlock(&root->d_inode->i_mutex);
}
static int __init init_devpts_fs(void)
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