diff options
Diffstat (limited to 'fs/overlayfs/params.c')
| -rw-r--r-- | fs/overlayfs/params.c | 983 |
1 files changed, 983 insertions, 0 deletions
diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c new file mode 100644 index 0000000000..f6ff23fd10 --- /dev/null +++ b/fs/overlayfs/params.c @@ -0,0 +1,983 @@ +// 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_verity, + Opt_volatile, +}; + +static const struct constant_table ovl_parameter_bool[] = { + { "on", true }, + { "off", false }, + {} +}; + +static const struct constant_table ovl_parameter_uuid[] = { + { "off", OVL_UUID_OFF }, + { "null", OVL_UUID_NULL }, + { "auto", OVL_UUID_AUTO }, + { "on", OVL_UUID_ON }, + {} +}; + +static const char *ovl_uuid_mode(struct ovl_config *config) +{ + return ovl_parameter_uuid[config->uuid].name; +} + +static int ovl_uuid_def(void) +{ + return OVL_UUID_AUTO; +} + +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; +} + +static const struct constant_table ovl_parameter_verity[] = { + { "off", OVL_VERITY_OFF }, + { "on", OVL_VERITY_ON }, + { "require", OVL_VERITY_REQUIRE }, + {} +}; + +static const char *ovl_verity_mode(struct ovl_config *config) +{ + return ovl_parameter_verity[config->verity_mode].name; +} + +static int ovl_verity_mode_def(void) +{ + return OVL_VERITY_OFF; +} + +#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_uuid), + 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_enum("verity", Opt_verity, ovl_parameter_verity), + fsparam_flag("volatile", Opt_volatile), + {} +}; + +static char *ovl_next_opt(char **s) +{ + char *sbegin = *s; + char *p; + + if (sbegin == NULL) + return NULL; + + for (p = sbegin; *p; p++) { + if (*p == '\\') { + p++; + if (!*p) + break; + } else if (*p == ',') { + *p = '\0'; + *s = p + 1; + return sbegin; + } + } + *s = NULL; + return sbegin; +} + +static int ovl_parse_monolithic(struct fs_context *fc, void *data) +{ + return vfs_parse_monolithic_sep(fc, data, ovl_next_opt); +} + +static ssize_t ovl_parse_param_split_lowerdirs(char *str) +{ + ssize_t nr_layers = 1, nr_colons = 0; + char *s, *d; + + for (s = d = str;; s++, d++) { + if (*s == '\\') { + /* keep esc chars in split lowerdir */ + *d++ = *s++; + } else if (*s == ':') { + bool next_colon = (*(s + 1) == ':'); + + nr_colons++; + if (nr_colons == 2 && next_colon) { + pr_err("only single ':' or double '::' sequences of unescaped colons in lowerdir mount option allowed.\n"); + return -EINVAL; + } + /* count layers, not colons */ + if (!next_colon) + nr_layers++; + + *d = '\0'; + continue; + } + + *d = *s; + if (!*s) { + /* trailing colons */ + if (nr_colons) { + pr_err("unescaped trailing colons in lowerdir mount option.\n"); + return -EINVAL; + } + break; + } + nr_colons = 0; + } + + return nr_layers; +} + +static int ovl_mount_dir_noesc(const char *name, struct path *path) +{ + int err = -EINVAL; + + if (!*name) { + pr_err("empty lowerdir\n"); + goto out; + } + err = kern_path(name, LOOKUP_FOLLOW, path); + if (err) { + pr_err("failed to resolve '%s': %i\n", name, err); + goto out; + } + err = -EINVAL; + if (ovl_dentry_weird(path->dentry)) { + pr_err("filesystem on '%s' not supported\n", name); + goto out_put; + } + if (!d_is_dir(path->dentry)) { + pr_err("'%s' not a directory\n", name); + goto out_put; + } + return 0; + +out_put: + path_put_init(path); +out: + return err; +} + +static void ovl_unescape(char *s) +{ + char *d = s; + + for (;; s++, d++) { + if (*s == '\\') + s++; + *d = *s; + if (!*s) + break; + } +} + +static int ovl_mount_dir(const char *name, struct path *path, bool upper) +{ + int err = -ENOMEM; + char *tmp = kstrdup(name, GFP_KERNEL); + + if (tmp) { + ovl_unescape(tmp); + err = ovl_mount_dir_noesc(tmp, path); + + if (!err && upper && path->dentry->d_flags & DCACHE_OP_REAL) { + pr_err("filesystem on '%s' not supported as upperdir\n", + tmp); + path_put_init(path); + err = -EINVAL; + } + kfree(tmp); + } + return err; +} + +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; + struct ovl_config *config = &ofs->config; + struct ovl_fs_context *ctx = fc->fs_private; + struct path path; + char *dup; + + err = ovl_mount_dir(name, &path, true); + if (err) + return err; + + /* + * Check whether upper path is read-only here to report failures + * early. Don't forget to recheck when the superblock is created + * as the mount attributes could change. + */ + if (__mnt_is_readonly(path.mnt)) { + path_put(&path); + return -EINVAL; + } + + dup = kstrdup(name, GFP_KERNEL); + if (!dup) { + path_put(&path); + return -ENOMEM; + } + + if (workdir) { + kfree(config->workdir); + config->workdir = dup; + path_put(&ctx->work); + ctx->work = path; + } else { + kfree(config->upperdir); + config->upperdir = dup; + path_put(&ctx->upper); + ctx->upper = path; + } + return 0; +} + +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); + kfree(ctx->lower[nr].name); + ctx->lower[nr].name = NULL; + } + ctx->nr = 0; + ctx->nr_data = 0; +} + +/* + * Parse lowerdir= mount option: + * + * (1) lowerdir=/lower1:/lower2:/lower3::/data1::/data2 + * Set "/lower1", "/lower2", and "/lower3" as lower layers and + * "/data1" and "/data2" as data lower layers. Any existing lower + * layers are replaced. + */ +static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) +{ + int err; + struct ovl_fs_context *ctx = fc->fs_private; + struct ovl_fs_context_layer *l; + char *dup = NULL, *dup_iter; + ssize_t nr_lower = 0, nr = 0, nr_data = 0; + bool append = false, data_layer = false; + + /* + * Ensure we're backwards compatible with mount(2) + * by allowing relative paths. + */ + + /* drop all existing lower layers */ + if (!*name) { + ovl_parse_param_drop_lowerdir(ctx); + return 0; + } + + if (*name == ':') { + pr_err("cannot append lower layer"); + return -EINVAL; + } + + dup = kstrdup(name, GFP_KERNEL); + if (!dup) + return -ENOMEM; + + err = -EINVAL; + nr_lower = ovl_parse_param_split_lowerdirs(dup); + if (nr_lower < 0) + goto out_err; + + if ((nr_lower > OVL_MAX_STACK) || + (append && (size_add(ctx->nr, nr_lower) > OVL_MAX_STACK))) { + pr_err("too many lower directories, limit is %d\n", OVL_MAX_STACK); + goto out_err; + } + + if (!append) + ovl_parse_param_drop_lowerdir(ctx); + + /* + * (1) append + * + * We want nr <= nr_lower <= capacity We know nr > 0 and nr <= + * capacity. If nr == 0 this wouldn't be append. If nr + + * nr_lower is <= capacity then nr <= nr_lower <= capacity + * already holds. If nr + nr_lower exceeds capacity, we realloc. + * + * (2) replace + * + * Ensure we're backwards compatible with mount(2) which allows + * "lowerdir=/a:/b:/c,lowerdir=/d:/e:/f" causing the last + * specified lowerdir mount option to win. + * + * We want nr <= nr_lower <= capacity We know either (i) nr == 0 + * or (ii) nr > 0. We also know nr_lower > 0. The capacity + * could've been changed multiple times already so we only know + * nr <= capacity. If nr + nr_lower > capacity we realloc, + * otherwise nr <= nr_lower <= capacity holds already. + */ + nr_lower += ctx->nr; + if (nr_lower > ctx->capacity) { + err = -ENOMEM; + l = krealloc_array(ctx->lower, nr_lower, sizeof(*ctx->lower), + GFP_KERNEL_ACCOUNT); + if (!l) + goto out_err; + + ctx->lower = l; + ctx->capacity = nr_lower; + } + + /* + * (3) By (1) and (2) we know nr <= nr_lower <= capacity. + * (4) If ctx->nr == 0 => replace + * We have verified above that the lowerdir mount option + * isn't an append, i.e., the lowerdir mount option + * doesn't start with ":" or "::". + * (4.1) The lowerdir mount options only contains regular lower + * layers ":". + * => Nothing to verify. + * (4.2) The lowerdir mount options contains regular ":" and + * data "::" layers. + * => We need to verify that data lower layers "::" aren't + * followed by regular ":" lower layers + * (5) If ctx->nr > 0 => append + * We know that there's at least one regular layer + * otherwise we would've failed when parsing the previous + * lowerdir mount option. + * (5.1) The lowerdir mount option is a regular layer ":" append + * => We need to verify that no data layers have been + * specified before. + * (5.2) The lowerdir mount option is a data layer "::" append + * We know that there's at least one regular layer or + * other data layers. => There's nothing to verify. + */ + dup_iter = dup; + for (nr = ctx->nr; nr < nr_lower; nr++) { + l = &ctx->lower[nr]; + memset(l, 0, sizeof(*l)); + + err = ovl_mount_dir(dup_iter, &l->path, false); + if (err) + goto out_put; + + err = -ENOMEM; + l->name = kstrdup(dup_iter, GFP_KERNEL_ACCOUNT); + if (!l->name) + goto out_put; + + if (data_layer) + nr_data++; + + /* Calling strchr() again would overrun. */ + if ((nr + 1) == nr_lower) + break; + + err = -EINVAL; + dup_iter = strchr(dup_iter, '\0') + 1; + if (*dup_iter) { + /* + * This is a regular layer so we require that + * there are no data layers. + */ + if ((ctx->nr_data + nr_data) > 0) { + pr_err("regular lower layers cannot follow data lower layers"); + goto out_put; + } + + data_layer = false; + continue; + } + + /* This is a data lower layer. */ + data_layer = true; + dup_iter++; + } + ctx->nr = nr_lower; + ctx->nr_data += nr_data; + kfree(dup); + return 0; + +out_put: + /* + * We know nr >= ctx->nr < nr_lower. If we failed somewhere + * we want to undo until nr == ctx->nr. This is correct for + * both ctx->nr == 0 and ctx->nr > 0. + */ + for (; nr >= ctx->nr; nr--) { + l = &ctx->lower[nr]; + kfree(l->name); + l->name = NULL; + path_put(&l->path); + + /* don't overflow */ + if (nr == 0) + break; + } + +out_err: + kfree(dup); + + /* 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_verity: + config->verity_mode = result.uint_32; + 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 = OVL_FS(sb); + 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_monolithic = ovl_parse_monolithic, + .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 = ovl_uuid_def(); + 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); + + /* Reuse ofs->config.lowerdirs as a vfsmount array before freeing it */ + mounts = (struct vfsmount **) ofs->config.lowerdirs; + for (i = 0; i < ofs->numlayer; i++) { + iput(ofs->layers[i].trap); + kfree(ofs->config.lowerdirs[i]); + mounts[i] = ofs->layers[i].mnt; + } + 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.lowerdirs); + 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; + } + + if (!config->upperdir && config->uuid == OVL_UUID_ON) { + pr_info("option \"uuid=on\" requires an upper fs, falling back to uuid=null.\n"); + config->uuid = OVL_UUID_NULL; + } + + /* Resolve verity -> metacopy dependency */ + if (config->verity_mode && !config->metacopy) { + /* Don't allow explicit specified conflicting combinations */ + if (set.metacopy) { + pr_err("conflicting options: metacopy=off,verity=%s\n", + ovl_verity_mode(config)); + return -EINVAL; + } + /* Otherwise automatically enable metacopy. */ + config->metacopy = true; + } + + /* + * 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 verity -> 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 (config->verity_mode && set.redirect) { + pr_err("conflicting options: verity=%s,redirect_dir=%s\n", + ovl_verity_mode(config), 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 && !verity 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 if (config->verity_mode) { + /* + * There was an explicit verity=.. that resulted + * in this conflict. + */ + pr_info("disabling nfs_export due to verity=%s\n", + ovl_verity_mode(config)); + 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 && !verity 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; + } + if (config->verity_mode) { + pr_err("conflicting options: userxattr,verity=%s\n", + ovl_verity_mode(config)); + 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 = OVL_FS(sb); + size_t nr, nr_merged_lower = ofs->numlayer - ofs->numdatalayer; + + /* + * lowerdirs[] starts from offset 1, then + * >= 0 regular lower layers prefixed with : and + * >= 0 data-only lower layers prefixed with :: + * + * we need to escase comma and space like seq_show_option() does and + * we also need to escape the colon separator from lowerdir paths. + */ + seq_puts(m, ",lowerdir="); + for (nr = 1; nr < ofs->numlayer; nr++) { + if (nr > 1) + seq_putc(m, ':'); + if (nr >= nr_merged_lower) + seq_putc(m, ':'); + seq_escape(m, ofs->config.lowerdirs[nr], ":, \t\n\\"); + } + 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 != ovl_uuid_def()) + seq_printf(m, ",uuid=%s", ovl_uuid_mode(&ofs->config)); + 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"); + if (ofs->config.verity_mode != ovl_verity_mode_def()) + seq_printf(m, ",verity=%s", + ovl_verity_mode(&ofs->config)); + return 0; +} |