On Wed, Mar 27, 2019 at 11:48:41PM +0000, David Howells wrote: > Convert the devpts filesystem to the new internal mount API as the old > one will be obsoleted and removed. This allows greater flexibility in > communication of mount parameters between userspace, the VFS and the > filesystem. > > See Documentation/filesystems/mount_api.txt for more information. > > Signed-off-by: David Howells <[email protected]> > cc: "Eric W. Biederman" <[email protected]> > cc: Christian Brauner <[email protected]>
One nit below otherwise: Acked-by: Christian Brauner <[email protected]> > --- > > fs/devpts/inode.c | 265 > +++++++++++++++++++++++++---------------------------- > 1 file changed, 124 insertions(+), 141 deletions(-) > > diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c > index 553a3f3300ae..ed4a49012570 100644 > --- a/fs/devpts/inode.c > +++ b/fs/devpts/inode.c > @@ -15,6 +15,8 @@ > #include <linux/module.h> > #include <linux/init.h> > #include <linux/fs.h> > +#include <linux/fs_context.h> > +#include <linux/fs_parser.h> > #include <linux/sched.h> > #include <linux/namei.h> > #include <linux/slab.h> > @@ -24,7 +26,6 @@ > #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> > > @@ -109,14 +110,19 @@ enum { > Opt_err > }; > > -static const match_table_t tokens = { > - {Opt_uid, "uid=%u"}, > - {Opt_gid, "gid=%u"}, > - {Opt_mode, "mode=%o"}, > - {Opt_ptmxmode, "ptmxmode=%o"}, > - {Opt_newinstance, "newinstance"}, > - {Opt_max, "max=%d"}, > - {Opt_err, NULL} > +static const struct fs_parameter_spec devpts_param_specs[] = { > + fsparam_u32 ("gid", Opt_gid), > + fsparam_s32 ("max", Opt_max), > + fsparam_u32oct ("mode", Opt_mode), > + fsparam_flag ("newinstance", Opt_newinstance), > + fsparam_u32oct ("ptmxmode", Opt_ptmxmode), > + fsparam_u32 ("uid", Opt_uid), > + {} > +}; > + > +static const struct fs_parameter_description devpts_fs_parameters = { > + .name = "devpts", > + .specs = devpts_param_specs, > }; > > struct pts_fs_info { > @@ -236,93 +242,56 @@ void devpts_release(struct pts_fs_info *fsi) > deactivate_super(fsi->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. > - * > - * Note: @data may be NULL (in which case all options are set to default). > + * devpts_parse_param - Parse mount parameters > */ > -static int parse_mount_options(char *data, int op, struct pts_mount_opts > *opts) > +static int devpts_parse_param(struct fs_context *fc, struct fs_parameter > *param) > { > - char *p; > + struct pts_fs_info *fsi = fc->s_fs_info; > + struct pts_mount_opts *opts = &fsi->mount_opts; > + struct fs_parse_result result; > kuid_t uid; > kgid_t gid; > - > - opts->setuid = 0; > - opts->setgid = 0; > - opts->uid = GLOBAL_ROOT_UID; > - opts->gid = GLOBAL_ROOT_GID; > - opts->mode = DEVPTS_DEFAULT_MODE; > - opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; > - opts->max = NR_UNIX98_PTY_MAX; > - > - /* Only allow instances mounted from the initial mount > - * namespace to tap the reserve pool of ptys. > - */ > - if (op == PARSE_MOUNT) > - opts->reserve = > - (current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns); > - > - while ((p = strsep(&data, ",")) != NULL) { > - substring_t args[MAX_OPT_ARGS]; > - int token; > - int option; > - > - if (!*p) > - continue; > - > - token = match_token(p, tokens, args); > - switch (token) { > - case Opt_uid: > - if (match_int(&args[0], &option)) > - return -EINVAL; > - uid = make_kuid(current_user_ns(), option); > - if (!uid_valid(uid)) > - return -EINVAL; > - opts->uid = uid; > - opts->setuid = 1; > - break; > - case Opt_gid: > - if (match_int(&args[0], &option)) > - return -EINVAL; > - gid = make_kgid(current_user_ns(), option); > - if (!gid_valid(gid)) > - return -EINVAL; > - opts->gid = gid; > - opts->setgid = 1; > - break; > - case Opt_mode: > - if (match_octal(&args[0], &option)) > - return -EINVAL; > - opts->mode = option & S_IALLUGO; > - break; > - case Opt_ptmxmode: > - if (match_octal(&args[0], &option)) > - return -EINVAL; > - opts->ptmxmode = option & S_IALLUGO; > - break; > - case Opt_newinstance: > - break; > - case Opt_max: > - if (match_int(&args[0], &option) || > - option < 0 || option > NR_UNIX98_PTY_MAX) > - return -EINVAL; > - opts->max = option; > - break; > - default: > - pr_err("called with bogus options\n"); > - return -EINVAL; > - } > + int opt; > + > + opt = fs_parse(fc, &devpts_fs_parameters, param, &result); > + if (opt < 0) > + return opt; > + > + switch (opt) { > + case Opt_uid: > + uid = make_kuid(current_user_ns(), result.uint_32); > + if (!uid_valid(uid)) > + return invalf(fc, "Unknown uid"); > + opts->uid = uid; > + opts->setuid = 1; > + break; > + case Opt_gid: > + gid = make_kgid(current_user_ns(), result.uint_32); > + if (!gid_valid(gid)) > + return invalf(fc, "Unknown gid"); > + opts->gid = gid; > + opts->setgid = 1; > + break; > + case Opt_mode: > + opts->mode = result.uint_32 & S_IALLUGO; > + break; > + case Opt_ptmxmode: > + opts->ptmxmode = result.uint_32 & S_IALLUGO; > + break; > + case Opt_newinstance: > + break; > + case Opt_max: > + if (result.uint_32 > NR_UNIX98_PTY_MAX) > + return invalf(fc, "max out of range"); > + opts->max = result.uint_32; > + break; > } > > return 0; > } > > -static int mknod_ptmx(struct super_block *sb) > +static int mknod_ptmx(struct super_block *sb, struct fs_context *fc) > { > int mode; > int rc = -ENOMEM; > @@ -344,7 +313,7 @@ static int mknod_ptmx(struct super_block *sb) > > dentry = d_alloc_name(root, "ptmx"); > if (!dentry) { > - pr_err("Unable to alloc dentry for ptmx node\n"); > + errorf(fc, "Unable to alloc dentry for ptmx node\n"); > goto out; > } > > @@ -353,7 +322,7 @@ static int mknod_ptmx(struct super_block *sb) > */ > inode = new_inode(sb); > if (!inode) { > - pr_err("Unable to alloc inode for ptmx node\n"); > + errorf(fc, "Unable to alloc inode for ptmx node\n"); > dput(dentry); > goto out; > } > @@ -384,13 +353,23 @@ static void update_ptmx_mode(struct pts_fs_info *fsi) > } > } > > -static int devpts_remount(struct super_block *sb, int *flags, char *data) > +static int devpts_reconfigure(struct fs_context *fc) > { > - int err; > - struct pts_fs_info *fsi = DEVPTS_SB(sb); > - struct pts_mount_opts *opts = &fsi->mount_opts; > + struct pts_fs_info *fsi = DEVPTS_SB(fc->root->d_sb); > + struct pts_fs_info *new = fc->s_fs_info; > > - err = parse_mount_options(data, PARSE_REMOUNT, opts); > + /* Apply the revised options. We don't want to change ->reserve. > + * Ideally, we'd update each option conditionally on it having being s/being/been/ ? > + * explicitly changed, but the default is to reset everything so that > + * would break UAPI... > + */ > + fsi->mount_opts.setuid = new->mount_opts.setuid; > + fsi->mount_opts.setgid = new->mount_opts.setgid; > + fsi->mount_opts.uid = new->mount_opts.uid; > + fsi->mount_opts.gid = new->mount_opts.gid; > + fsi->mount_opts.mode = new->mount_opts.mode; > + fsi->mount_opts.ptmxmode = new->mount_opts.ptmxmode; > + fsi->mount_opts.max = new->mount_opts.max; > > /* > * parse_mount_options() restores options to default values > @@ -400,7 +379,7 @@ static int devpts_remount(struct super_block *sb, int > *flags, char *data) > */ > update_ptmx_mode(fsi); > > - return err; > + return 0; > } > > static int devpts_show_options(struct seq_file *seq, struct dentry *root) > @@ -424,31 +403,13 @@ static int devpts_show_options(struct seq_file *seq, > struct dentry *root) > > 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(struct super_block *sb) > -{ > - 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; > - fsi->sb = sb; > - > - return fsi; > -} > - > -static int > -devpts_fill_super(struct super_block *s, void *data, int silent) > +static int devpts_fill_super(struct super_block *s, struct fs_context *fc) > { > + struct pts_fs_info *fsi = DEVPTS_SB(s); > struct inode *inode; > - int error; > > s->s_iflags &= ~SB_I_NODEV; > s->s_blocksize = 1024; > @@ -457,20 +418,12 @@ devpts_fill_super(struct super_block *s, void *data, > int silent) > s->s_op = &devpts_sops; > s->s_d_op = &simple_dentry_operations; > s->s_time_gran = 1; > + fsi->sb = s; > > - error = -ENOMEM; > - s->s_fs_info = new_pts_fs_info(s); > - if (!s->s_fs_info) > - goto fail; > - > - error = parse_mount_options(data, PARSE_MOUNT, > &DEVPTS_SB(s)->mount_opts); > - if (error) > - goto fail; > - > - error = -ENOMEM; > inode = new_inode(s); > if (!inode) > - goto fail; > + return -ENOMEM; > + > inode->i_ino = 1; > inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); > inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR; > @@ -480,20 +433,11 @@ devpts_fill_super(struct super_block *s, void *data, > int silent) > > s->s_root = d_make_root(inode); > if (!s->s_root) { > - pr_err("get root dentry failed\n"); > - goto fail; > + errorf(fc, "get root dentry failed"); > + return -ENOMEM; > } > > - error = mknod_ptmx(s); > - if (error) > - goto fail_dput; > - > - return 0; > -fail_dput: > - dput(s->s_root); > - s->s_root = NULL; > -fail: > - return error; > + return mknod_ptmx(s, fc); > } > > /* > @@ -502,10 +446,48 @@ devpts_fill_super(struct super_block *s, void *data, > int silent) > * 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) > +static int devpts_get_tree(struct fs_context *fc) > +{ > + return vfs_get_super(fc, vfs_get_independent_super, devpts_fill_super); > +} > + > +static void devpts_free_fc(struct fs_context *fc) > +{ > + kfree(fc->s_fs_info); > +} > + > +static const struct fs_context_operations devpts_context_ops = { > + .free = devpts_free_fc, > + .parse_param = devpts_parse_param, > + .get_tree = devpts_get_tree, > + .reconfigure = devpts_reconfigure, > +}; > + > +/* > + * Set up the filesystem mount context. > + */ > +static int devpts_init_fs_context(struct fs_context *fc) > { > - return mount_nodev(fs_type, flags, data, devpts_fill_super); > + struct pts_fs_info *fsi; > + > + fsi = kzalloc(sizeof(struct pts_fs_info), GFP_KERNEL); > + if (!fsi) > + return -ENOMEM; > + > + ida_init(&fsi->allocated_ptys); > + fsi->mount_opts.uid = GLOBAL_ROOT_UID; > + fsi->mount_opts.gid = GLOBAL_ROOT_GID; > + fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; > + fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; > + fsi->mount_opts.max = NR_UNIX98_PTY_MAX; > + > + if (fc->purpose == FS_CONTEXT_FOR_MOUNT && > + current->nsproxy->mnt_ns == init_task.nsproxy->mnt_ns) > + fsi->mount_opts.reserve = true; > + > + fc->s_fs_info = fsi; > + fc->ops = &devpts_context_ops; > + return 0; > } > > static void devpts_kill_sb(struct super_block *sb) > @@ -520,7 +502,8 @@ static void devpts_kill_sb(struct super_block *sb) > > static struct file_system_type devpts_fs_type = { > .name = "devpts", > - .mount = devpts_mount, > + .init_fs_context = devpts_init_fs_context, > + .parameters = &devpts_fs_parameters, > .kill_sb = devpts_kill_sb, > .fs_flags = FS_USERNS_MOUNT, > }; >
