diff options
Diffstat (limited to 'fs/overlayfs/params.c')
-rw-r--r-- | fs/overlayfs/params.c | 532 |
1 files changed, 528 insertions, 4 deletions
diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c index d17d6b483dd0..a63160dbb0f9 100644 --- a/fs/overlayfs/params.c +++ b/fs/overlayfs/params.c @@ -1,12 +1,124 @@ // SPDX-License-Identifier: GPL-2.0-only #include <linux/fs.h> +#include <linux/module.h> #include <linux/namei.h> #include <linux/fs_context.h> #include <linux/fs_parser.h> #include <linux/posix_acl_xattr.h> +#include <linux/seq_file.h> #include <linux/xattr.h> #include "overlayfs.h" +#include "params.h" + +static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR); +module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644); +MODULE_PARM_DESC(redirect_dir, + "Default to on or off for the redirect_dir feature"); + +static bool ovl_redirect_always_follow = + IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW); +module_param_named(redirect_always_follow, ovl_redirect_always_follow, + bool, 0644); +MODULE_PARM_DESC(redirect_always_follow, + "Follow redirects even if redirect_dir feature is turned off"); + +static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO); +module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644); +MODULE_PARM_DESC(xino_auto, + "Auto enable xino feature"); + +static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX); +module_param_named(index, ovl_index_def, bool, 0644); +MODULE_PARM_DESC(index, + "Default to on or off for the inodes index feature"); + +static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT); +module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644); +MODULE_PARM_DESC(nfs_export, + "Default to on or off for the NFS export feature"); + +static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY); +module_param_named(metacopy, ovl_metacopy_def, bool, 0644); +MODULE_PARM_DESC(metacopy, + "Default to on or off for the metadata only copy up feature"); + +enum { + Opt_lowerdir, + Opt_upperdir, + Opt_workdir, + Opt_default_permissions, + Opt_redirect_dir, + Opt_index, + Opt_uuid, + Opt_nfs_export, + Opt_userxattr, + Opt_xino, + Opt_metacopy, + Opt_volatile, +}; + +static const struct constant_table ovl_parameter_bool[] = { + { "on", true }, + { "off", false }, + {} +}; + +static const struct constant_table ovl_parameter_xino[] = { + { "off", OVL_XINO_OFF }, + { "auto", OVL_XINO_AUTO }, + { "on", OVL_XINO_ON }, + {} +}; + +const char *ovl_xino_mode(struct ovl_config *config) +{ + return ovl_parameter_xino[config->xino].name; +} + +static int ovl_xino_def(void) +{ + return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF; +} + +const struct constant_table ovl_parameter_redirect_dir[] = { + { "off", OVL_REDIRECT_OFF }, + { "follow", OVL_REDIRECT_FOLLOW }, + { "nofollow", OVL_REDIRECT_NOFOLLOW }, + { "on", OVL_REDIRECT_ON }, + {} +}; + +static const char *ovl_redirect_mode(struct ovl_config *config) +{ + return ovl_parameter_redirect_dir[config->redirect_mode].name; +} + +static int ovl_redirect_mode_def(void) +{ + return ovl_redirect_dir_def ? OVL_REDIRECT_ON : + ovl_redirect_always_follow ? OVL_REDIRECT_FOLLOW : + OVL_REDIRECT_NOFOLLOW; +} + +#define fsparam_string_empty(NAME, OPT) \ + __fsparam(fs_param_is_string, NAME, OPT, fs_param_can_be_empty, NULL) + +const struct fs_parameter_spec ovl_parameter_spec[] = { + fsparam_string_empty("lowerdir", Opt_lowerdir), + fsparam_string("upperdir", Opt_upperdir), + fsparam_string("workdir", Opt_workdir), + fsparam_flag("default_permissions", Opt_default_permissions), + fsparam_enum("redirect_dir", Opt_redirect_dir, ovl_parameter_redirect_dir), + fsparam_enum("index", Opt_index, ovl_parameter_bool), + fsparam_enum("uuid", Opt_uuid, ovl_parameter_bool), + fsparam_enum("nfs_export", Opt_nfs_export, ovl_parameter_bool), + fsparam_flag("userxattr", Opt_userxattr), + fsparam_enum("xino", Opt_xino, ovl_parameter_xino), + fsparam_enum("metacopy", Opt_metacopy, ovl_parameter_bool), + fsparam_flag("volatile", Opt_volatile), + {} +}; static ssize_t ovl_parse_param_split_lowerdirs(char *str) { @@ -110,8 +222,8 @@ static int ovl_mount_dir(const char *name, struct path *path) return err; } -int ovl_parse_param_upperdir(const char *name, struct fs_context *fc, - bool workdir) +static int ovl_parse_param_upperdir(const char *name, struct fs_context *fc, + bool workdir) { int err; struct ovl_fs *ofs = fc->s_fs_info; @@ -154,7 +266,7 @@ int ovl_parse_param_upperdir(const char *name, struct fs_context *fc, return 0; } -void ovl_parse_param_drop_lowerdir(struct ovl_fs_context *ctx) +static void ovl_parse_param_drop_lowerdir(struct ovl_fs_context *ctx) { for (size_t nr = 0; nr < ctx->nr; nr++) { path_put(&ctx->lower[nr].path); @@ -179,7 +291,7 @@ void ovl_parse_param_drop_lowerdir(struct ovl_fs_context *ctx) * Append data "/lower5" as data lower layer. This requires that * there's at least one regular lower layer present. */ -int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) +static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) { int err; struct ovl_fs_context *ctx = fc->fs_private; @@ -387,3 +499,415 @@ out_err: /* Intentionally don't realloc to a smaller size. */ return err; } + +static int ovl_parse_param(struct fs_context *fc, struct fs_parameter *param) +{ + int err = 0; + struct fs_parse_result result; + struct ovl_fs *ofs = fc->s_fs_info; + struct ovl_config *config = &ofs->config; + struct ovl_fs_context *ctx = fc->fs_private; + int opt; + + if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) { + /* + * On remount overlayfs has always ignored all mount + * options no matter if malformed or not so for + * backwards compatibility we do the same here. + */ + if (fc->oldapi) + return 0; + + /* + * Give us the freedom to allow changing mount options + * with the new mount api in the future. So instead of + * silently ignoring everything we report a proper + * error. This is only visible for users of the new + * mount api. + */ + return invalfc(fc, "No changes allowed in reconfigure"); + } + + opt = fs_parse(fc, ovl_parameter_spec, param, &result); + if (opt < 0) + return opt; + + switch (opt) { + case Opt_lowerdir: + err = ovl_parse_param_lowerdir(param->string, fc); + break; + case Opt_upperdir: + fallthrough; + case Opt_workdir: + err = ovl_parse_param_upperdir(param->string, fc, + (Opt_workdir == opt)); + break; + case Opt_default_permissions: + config->default_permissions = true; + break; + case Opt_redirect_dir: + config->redirect_mode = result.uint_32; + if (config->redirect_mode == OVL_REDIRECT_OFF) { + config->redirect_mode = ovl_redirect_always_follow ? + OVL_REDIRECT_FOLLOW : + OVL_REDIRECT_NOFOLLOW; + } + ctx->set.redirect = true; + break; + case Opt_index: + config->index = result.uint_32; + ctx->set.index = true; + break; + case Opt_uuid: + config->uuid = result.uint_32; + break; + case Opt_nfs_export: + config->nfs_export = result.uint_32; + ctx->set.nfs_export = true; + break; + case Opt_xino: + config->xino = result.uint_32; + break; + case Opt_metacopy: + config->metacopy = result.uint_32; + ctx->set.metacopy = true; + break; + case Opt_volatile: + config->ovl_volatile = true; + break; + case Opt_userxattr: + config->userxattr = true; + break; + default: + pr_err("unrecognized mount option \"%s\" or missing value\n", + param->key); + return -EINVAL; + } + + return err; +} + +static int ovl_get_tree(struct fs_context *fc) +{ + return get_tree_nodev(fc, ovl_fill_super); +} + +static inline void ovl_fs_context_free(struct ovl_fs_context *ctx) +{ + ovl_parse_param_drop_lowerdir(ctx); + path_put(&ctx->upper); + path_put(&ctx->work); + kfree(ctx->lower); + kfree(ctx); +} + +static void ovl_free(struct fs_context *fc) +{ + struct ovl_fs *ofs = fc->s_fs_info; + struct ovl_fs_context *ctx = fc->fs_private; + + /* + * ofs is stored in the fs_context when it is initialized. + * ofs is transferred to the superblock on a successful mount, + * but if an error occurs before the transfer we have to free + * it here. + */ + if (ofs) + ovl_free_fs(ofs); + + if (ctx) + ovl_fs_context_free(ctx); +} + +static int ovl_reconfigure(struct fs_context *fc) +{ + struct super_block *sb = fc->root->d_sb; + struct ovl_fs *ofs = sb->s_fs_info; + struct super_block *upper_sb; + int ret = 0; + + if (!(fc->sb_flags & SB_RDONLY) && ovl_force_readonly(ofs)) + return -EROFS; + + if (fc->sb_flags & SB_RDONLY && !sb_rdonly(sb)) { + upper_sb = ovl_upper_mnt(ofs)->mnt_sb; + if (ovl_should_sync(ofs)) { + down_read(&upper_sb->s_umount); + ret = sync_filesystem(upper_sb); + up_read(&upper_sb->s_umount); + } + } + + return ret; +} + +static const struct fs_context_operations ovl_context_ops = { + .parse_param = ovl_parse_param, + .get_tree = ovl_get_tree, + .reconfigure = ovl_reconfigure, + .free = ovl_free, +}; + +/* + * This is called during fsopen() and will record the user namespace of + * the caller in fc->user_ns since we've raised FS_USERNS_MOUNT. We'll + * need it when we actually create the superblock to verify that the + * process creating the superblock is in the same user namespace as + * process that called fsopen(). + */ +int ovl_init_fs_context(struct fs_context *fc) +{ + struct ovl_fs_context *ctx; + struct ovl_fs *ofs; + + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT); + if (!ctx) + return -ENOMEM; + + /* + * By default we allocate for three lower layers. It's likely + * that it'll cover most users. + */ + ctx->lower = kmalloc_array(3, sizeof(*ctx->lower), GFP_KERNEL_ACCOUNT); + if (!ctx->lower) + goto out_err; + ctx->capacity = 3; + + ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); + if (!ofs) + goto out_err; + + ofs->config.redirect_mode = ovl_redirect_mode_def(); + ofs->config.index = ovl_index_def; + ofs->config.uuid = true; + ofs->config.nfs_export = ovl_nfs_export_def; + ofs->config.xino = ovl_xino_def(); + ofs->config.metacopy = ovl_metacopy_def; + + fc->s_fs_info = ofs; + fc->fs_private = ctx; + fc->ops = &ovl_context_ops; + return 0; + +out_err: + ovl_fs_context_free(ctx); + return -ENOMEM; + +} + +void ovl_free_fs(struct ovl_fs *ofs) +{ + struct vfsmount **mounts; + unsigned i; + + iput(ofs->workbasedir_trap); + iput(ofs->indexdir_trap); + iput(ofs->workdir_trap); + dput(ofs->whiteout); + dput(ofs->indexdir); + dput(ofs->workdir); + if (ofs->workdir_locked) + ovl_inuse_unlock(ofs->workbasedir); + dput(ofs->workbasedir); + if (ofs->upperdir_locked) + ovl_inuse_unlock(ovl_upper_mnt(ofs)->mnt_root); + + /* Hack! Reuse ofs->layers as a vfsmount array before freeing it */ + mounts = (struct vfsmount **) ofs->layers; + for (i = 0; i < ofs->numlayer; i++) { + iput(ofs->layers[i].trap); + mounts[i] = ofs->layers[i].mnt; + kfree(ofs->layers[i].name); + } + kern_unmount_array(mounts, ofs->numlayer); + kfree(ofs->layers); + for (i = 0; i < ofs->numfs; i++) + free_anon_bdev(ofs->fs[i].pseudo_dev); + kfree(ofs->fs); + + kfree(ofs->config.upperdir); + kfree(ofs->config.workdir); + if (ofs->creator_cred) + put_cred(ofs->creator_cred); + kfree(ofs); +} + +int ovl_fs_params_verify(const struct ovl_fs_context *ctx, + struct ovl_config *config) +{ + struct ovl_opt_set set = ctx->set; + + if (ctx->nr_data > 0 && !config->metacopy) { + pr_err("lower data-only dirs require metacopy support.\n"); + return -EINVAL; + } + + /* Workdir/index are useless in non-upper mount */ + if (!config->upperdir) { + if (config->workdir) { + pr_info("option \"workdir=%s\" is useless in a non-upper mount, ignore\n", + config->workdir); + kfree(config->workdir); + config->workdir = NULL; + } + if (config->index && set.index) { + pr_info("option \"index=on\" is useless in a non-upper mount, ignore\n"); + set.index = false; + } + config->index = false; + } + + if (!config->upperdir && config->ovl_volatile) { + pr_info("option \"volatile\" is meaningless in a non-upper mount, ignoring it.\n"); + config->ovl_volatile = false; + } + + /* + * This is to make the logic below simpler. It doesn't make any other + * difference, since redirect_dir=on is only used for upper. + */ + if (!config->upperdir && config->redirect_mode == OVL_REDIRECT_FOLLOW) + config->redirect_mode = OVL_REDIRECT_ON; + + /* Resolve metacopy -> redirect_dir dependency */ + if (config->metacopy && config->redirect_mode != OVL_REDIRECT_ON) { + if (set.metacopy && set.redirect) { + pr_err("conflicting options: metacopy=on,redirect_dir=%s\n", + ovl_redirect_mode(config)); + return -EINVAL; + } + if (set.redirect) { + /* + * There was an explicit redirect_dir=... that resulted + * in this conflict. + */ + pr_info("disabling metacopy due to redirect_dir=%s\n", + ovl_redirect_mode(config)); + config->metacopy = false; + } else { + /* Automatically enable redirect otherwise. */ + config->redirect_mode = OVL_REDIRECT_ON; + } + } + + /* Resolve nfs_export -> index dependency */ + if (config->nfs_export && !config->index) { + if (!config->upperdir && + config->redirect_mode != OVL_REDIRECT_NOFOLLOW) { + pr_info("NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n"); + config->nfs_export = false; + } else if (set.nfs_export && set.index) { + pr_err("conflicting options: nfs_export=on,index=off\n"); + return -EINVAL; + } else if (set.index) { + /* + * There was an explicit index=off that resulted + * in this conflict. + */ + pr_info("disabling nfs_export due to index=off\n"); + config->nfs_export = false; + } else { + /* Automatically enable index otherwise. */ + config->index = true; + } + } + + /* Resolve nfs_export -> !metacopy dependency */ + if (config->nfs_export && config->metacopy) { + if (set.nfs_export && set.metacopy) { + pr_err("conflicting options: nfs_export=on,metacopy=on\n"); + return -EINVAL; + } + if (set.metacopy) { + /* + * There was an explicit metacopy=on that resulted + * in this conflict. + */ + pr_info("disabling nfs_export due to metacopy=on\n"); + config->nfs_export = false; + } else { + /* + * There was an explicit nfs_export=on that resulted + * in this conflict. + */ + pr_info("disabling metacopy due to nfs_export=on\n"); + config->metacopy = false; + } + } + + + /* Resolve userxattr -> !redirect && !metacopy dependency */ + if (config->userxattr) { + if (set.redirect && + config->redirect_mode != OVL_REDIRECT_NOFOLLOW) { + pr_err("conflicting options: userxattr,redirect_dir=%s\n", + ovl_redirect_mode(config)); + return -EINVAL; + } + if (config->metacopy && set.metacopy) { + pr_err("conflicting options: userxattr,metacopy=on\n"); + return -EINVAL; + } + /* + * Silently disable default setting of redirect and metacopy. + * This shall be the default in the future as well: these + * options must be explicitly enabled if used together with + * userxattr. + */ + config->redirect_mode = OVL_REDIRECT_NOFOLLOW; + config->metacopy = false; + } + + return 0; +} + +/** + * ovl_show_options + * @m: the seq_file handle + * @dentry: The dentry to query + * + * Prints the mount options for a given superblock. + * Returns zero; does not fail. + */ +int ovl_show_options(struct seq_file *m, struct dentry *dentry) +{ + struct super_block *sb = dentry->d_sb; + struct ovl_fs *ofs = sb->s_fs_info; + size_t nr, nr_merged_lower = ofs->numlayer - ofs->numdatalayer; + const struct ovl_layer *data_layers = &ofs->layers[nr_merged_lower]; + + /* ofs->layers[0] is the upper layer */ + seq_printf(m, ",lowerdir=%s", ofs->layers[1].name); + /* dump regular lower layers */ + for (nr = 2; nr < nr_merged_lower; nr++) + seq_printf(m, ":%s", ofs->layers[nr].name); + /* dump data lower layers */ + for (nr = 0; nr < ofs->numdatalayer; nr++) + seq_printf(m, "::%s", data_layers[nr].name); + if (ofs->config.upperdir) { + seq_show_option(m, "upperdir", ofs->config.upperdir); + seq_show_option(m, "workdir", ofs->config.workdir); + } + if (ofs->config.default_permissions) + seq_puts(m, ",default_permissions"); + if (ofs->config.redirect_mode != ovl_redirect_mode_def()) + seq_printf(m, ",redirect_dir=%s", + ovl_redirect_mode(&ofs->config)); + if (ofs->config.index != ovl_index_def) + seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off"); + if (!ofs->config.uuid) + seq_puts(m, ",uuid=off"); + if (ofs->config.nfs_export != ovl_nfs_export_def) + seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ? + "on" : "off"); + if (ofs->config.xino != ovl_xino_def() && !ovl_same_fs(ofs)) + seq_printf(m, ",xino=%s", ovl_xino_mode(&ofs->config)); + if (ofs->config.metacopy != ovl_metacopy_def) + seq_printf(m, ",metacopy=%s", + ofs->config.metacopy ? "on" : "off"); + if (ofs->config.ovl_volatile) + seq_puts(m, ",volatile"); + if (ofs->config.userxattr) + seq_puts(m, ",userxattr"); + return 0; +} |