diff options
Diffstat (limited to 'fs/overlayfs/super.c')
-rw-r--r-- | fs/overlayfs/super.c | 563 |
1 files changed, 62 insertions, 501 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index edd46a0e951d..20f48abbb82f 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -9,280 +9,29 @@ #include <linux/fs.h> #include <linux/namei.h> -#include <linux/pagemap.h> #include <linux/xattr.h> -#include <linux/security.h> #include <linux/mount.h> -#include <linux/slab.h> #include <linux/parser.h> #include <linux/module.h> -#include <linux/sched.h> #include <linux/statfs.h> #include <linux/seq_file.h> #include <linux/posix_acl_xattr.h> #include "overlayfs.h" +#include "ovl_entry.h" MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); MODULE_DESCRIPTION("Overlay filesystem"); MODULE_LICENSE("GPL"); -struct ovl_config { - char *lowerdir; - char *upperdir; - char *workdir; - bool default_permissions; -}; - -/* private information held for overlayfs's superblock */ -struct ovl_fs { - struct vfsmount *upper_mnt; - unsigned numlower; - struct vfsmount **lower_mnt; - struct dentry *workdir; - long lower_namelen; - /* pathnames of lower and upper dirs, for show_options */ - struct ovl_config config; - /* creds of process who forced instantiation of super block */ - const struct cred *creator_cred; -}; struct ovl_dir_cache; -/* private information held for every overlayfs dentry */ -struct ovl_entry { - struct dentry *__upperdentry; - struct ovl_dir_cache *cache; - union { - struct { - u64 version; - bool opaque; - }; - struct rcu_head rcu; - }; - unsigned numlower; - struct path lowerstack[]; -}; - #define OVL_MAX_STACK 500 -static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe) -{ - return oe->numlower ? oe->lowerstack[0].dentry : NULL; -} - -enum ovl_path_type ovl_path_type(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - enum ovl_path_type type = 0; - - if (oe->__upperdentry) { - type = __OVL_PATH_UPPER; - - /* - * Non-dir dentry can hold lower dentry from previous - * location. Its purity depends only on opaque flag. - */ - if (oe->numlower && S_ISDIR(dentry->d_inode->i_mode)) - type |= __OVL_PATH_MERGE; - else if (!oe->opaque) - type |= __OVL_PATH_PURE; - } else { - if (oe->numlower > 1) - type |= __OVL_PATH_MERGE; - } - return type; -} - -static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe) -{ - return lockless_dereference(oe->__upperdentry); -} - -void ovl_path_upper(struct dentry *dentry, struct path *path) -{ - struct ovl_fs *ofs = dentry->d_sb->s_fs_info; - struct ovl_entry *oe = dentry->d_fsdata; - - path->mnt = ofs->upper_mnt; - path->dentry = ovl_upperdentry_dereference(oe); -} - -enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) -{ - enum ovl_path_type type = ovl_path_type(dentry); - - if (!OVL_TYPE_UPPER(type)) - ovl_path_lower(dentry, path); - else - ovl_path_upper(dentry, path); - - return type; -} - -struct dentry *ovl_dentry_upper(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - return ovl_upperdentry_dereference(oe); -} - -struct dentry *ovl_dentry_lower(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - return __ovl_dentry_lower(oe); -} - -struct dentry *ovl_dentry_real(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - struct dentry *realdentry; - - realdentry = ovl_upperdentry_dereference(oe); - if (!realdentry) - realdentry = __ovl_dentry_lower(oe); - - return realdentry; -} - -static void ovl_inode_init(struct inode *inode, struct inode *realinode, - bool is_upper) -{ - WRITE_ONCE(inode->i_private, (unsigned long) realinode | - (is_upper ? OVL_ISUPPER_MASK : 0)); -} - -struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode, - bool is_upper) -{ - if (is_upper) { - struct ovl_fs *ofs = inode->i_sb->s_fs_info; - - return ofs->upper_mnt; - } else { - return oe->numlower ? oe->lowerstack[0].mnt : NULL; - } -} - -struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - return oe->cache; -} - -void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - oe->cache = cache; -} - -void ovl_path_lower(struct dentry *dentry, struct path *path) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - *path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL }; -} - -int ovl_want_write(struct dentry *dentry) -{ - struct ovl_fs *ofs = dentry->d_sb->s_fs_info; - return mnt_want_write(ofs->upper_mnt); -} - -void ovl_drop_write(struct dentry *dentry) -{ - struct ovl_fs *ofs = dentry->d_sb->s_fs_info; - mnt_drop_write(ofs->upper_mnt); -} - -struct dentry *ovl_workdir(struct dentry *dentry) -{ - struct ovl_fs *ofs = dentry->d_sb->s_fs_info; - return ofs->workdir; -} - -bool ovl_dentry_is_opaque(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - return oe->opaque; -} - -void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque) -{ - struct ovl_entry *oe = dentry->d_fsdata; - oe->opaque = opaque; -} - -void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode)); - WARN_ON(oe->__upperdentry); - /* - * Make sure upperdentry is consistent before making it visible to - * ovl_upperdentry_dereference(). - */ - smp_wmb(); - oe->__upperdentry = upperdentry; -} - -void ovl_inode_update(struct inode *inode, struct inode *upperinode) -{ - WARN_ON(!upperinode); - WARN_ON(!inode_unhashed(inode)); - WRITE_ONCE(inode->i_private, - (unsigned long) upperinode | OVL_ISUPPER_MASK); - if (!S_ISDIR(upperinode->i_mode)) - __insert_inode_hash(inode, (unsigned long) upperinode); -} - -void ovl_dentry_version_inc(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - WARN_ON(!inode_is_locked(dentry->d_inode)); - oe->version++; -} - -u64 ovl_dentry_version_get(struct dentry *dentry) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - WARN_ON(!inode_is_locked(dentry->d_inode)); - return oe->version; -} - -bool ovl_is_whiteout(struct dentry *dentry) -{ - struct inode *inode = dentry->d_inode; - - return inode && IS_WHITEOUT(inode); -} - -const struct cred *ovl_override_creds(struct super_block *sb) -{ - struct ovl_fs *ofs = sb->s_fs_info; - - return override_creds(ofs->creator_cred); -} - -static bool ovl_is_opaquedir(struct dentry *dentry) -{ - int res; - char val; - - if (!d_is_dir(dentry)) - return false; - - res = vfs_getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1); - if (res == 1 && val == 'y') - return true; - - return false; -} +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(ovl_redirect_dir_def, + "Default to on or off for the redirect_dir feature"); static void ovl_dentry_release(struct dentry *dentry) { @@ -292,6 +41,7 @@ static void ovl_dentry_release(struct dentry *dentry) unsigned int i; dput(oe->__upperdentry); + kfree(oe->redirect); for (i = 0; i < oe->numlower; i++) dput(oe->lowerstack[i].dentry); kfree_rcu(oe, rcu); @@ -304,7 +54,7 @@ static struct dentry *ovl_d_real(struct dentry *dentry, { struct dentry *real; - if (d_is_dir(dentry)) { + if (!d_is_reg(dentry)) { if (!inode || inode == d_inode(dentry)) return dentry; goto bug; @@ -328,11 +78,11 @@ static struct dentry *ovl_d_real(struct dentry *dentry, if (!real) goto bug; + /* Handle recursion */ + real = d_real(real, inode, open_flags); + if (!inode || inode == d_inode(real)) return real; - - /* Handle recursion */ - return d_real(real, inode, open_flags); bug: WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry, inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0); @@ -392,226 +142,6 @@ static const struct dentry_operations ovl_reval_dentry_operations = { .d_weak_revalidate = ovl_dentry_weak_revalidate, }; -static struct ovl_entry *ovl_alloc_entry(unsigned int numlower) -{ - size_t size = offsetof(struct ovl_entry, lowerstack[numlower]); - struct ovl_entry *oe = kzalloc(size, GFP_KERNEL); - - if (oe) - oe->numlower = numlower; - - return oe; -} - -static bool ovl_dentry_remote(struct dentry *dentry) -{ - return dentry->d_flags & - (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | - DCACHE_OP_REAL); -} - -static bool ovl_dentry_weird(struct dentry *dentry) -{ - return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT | - DCACHE_MANAGE_TRANSIT | - DCACHE_OP_HASH | - DCACHE_OP_COMPARE); -} - -static inline struct dentry *ovl_lookup_real(struct dentry *dir, - const struct qstr *name) -{ - struct dentry *dentry; - - dentry = lookup_one_len_unlocked(name->name, dir, name->len); - - if (IS_ERR(dentry)) { - if (PTR_ERR(dentry) == -ENOENT) - dentry = NULL; - } else if (!dentry->d_inode) { - dput(dentry); - dentry = NULL; - } else if (ovl_dentry_weird(dentry)) { - dput(dentry); - /* Don't support traversing automounts and other weirdness */ - dentry = ERR_PTR(-EREMOTE); - } - return dentry; -} - -/* - * Returns next layer in stack starting from top. - * Returns -1 if this is the last layer. - */ -int ovl_path_next(int idx, struct dentry *dentry, struct path *path) -{ - struct ovl_entry *oe = dentry->d_fsdata; - - BUG_ON(idx < 0); - if (idx == 0) { - ovl_path_upper(dentry, path); - if (path->dentry) - return oe->numlower ? 1 : -1; - idx++; - } - BUG_ON(idx > oe->numlower); - *path = oe->lowerstack[idx - 1]; - - return (idx < oe->numlower) ? idx + 1 : -1; -} - -struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, - unsigned int flags) -{ - struct ovl_entry *oe; - const struct cred *old_cred; - struct ovl_entry *poe = dentry->d_parent->d_fsdata; - struct path *stack = NULL; - struct dentry *upperdir, *upperdentry = NULL; - unsigned int ctr = 0; - struct inode *inode = NULL; - bool upperopaque = false; - struct dentry *this, *prev = NULL; - unsigned int i; - int err; - - old_cred = ovl_override_creds(dentry->d_sb); - upperdir = ovl_upperdentry_dereference(poe); - if (upperdir) { - this = ovl_lookup_real(upperdir, &dentry->d_name); - err = PTR_ERR(this); - if (IS_ERR(this)) - goto out; - - if (this) { - if (unlikely(ovl_dentry_remote(this))) { - dput(this); - err = -EREMOTE; - goto out; - } - if (ovl_is_whiteout(this)) { - dput(this); - this = NULL; - upperopaque = true; - } else if (poe->numlower && ovl_is_opaquedir(this)) { - upperopaque = true; - } - } - upperdentry = prev = this; - } - - if (!upperopaque && poe->numlower) { - err = -ENOMEM; - stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL); - if (!stack) - goto out_put_upper; - } - - for (i = 0; !upperopaque && i < poe->numlower; i++) { - bool opaque = false; - struct path lowerpath = poe->lowerstack[i]; - - this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name); - err = PTR_ERR(this); - if (IS_ERR(this)) { - /* - * If it's positive, then treat ENAMETOOLONG as ENOENT. - */ - if (err == -ENAMETOOLONG && (upperdentry || ctr)) - continue; - goto out_put; - } - if (!this) - continue; - if (ovl_is_whiteout(this)) { - dput(this); - break; - } - /* - * Only makes sense to check opaque dir if this is not the - * lowermost layer. - */ - if (i < poe->numlower - 1 && ovl_is_opaquedir(this)) - opaque = true; - - if (prev && (!S_ISDIR(prev->d_inode->i_mode) || - !S_ISDIR(this->d_inode->i_mode))) { - /* - * FIXME: check for upper-opaqueness maybe better done - * in remove code. - */ - if (prev == upperdentry) - upperopaque = true; - dput(this); - break; - } - /* - * If this is a non-directory then stop here. - */ - if (!S_ISDIR(this->d_inode->i_mode)) - opaque = true; - - stack[ctr].dentry = this; - stack[ctr].mnt = lowerpath.mnt; - ctr++; - prev = this; - if (opaque) - break; - } - - oe = ovl_alloc_entry(ctr); - err = -ENOMEM; - if (!oe) - goto out_put; - - if (upperdentry || ctr) { - struct dentry *realdentry; - struct inode *realinode; - - realdentry = upperdentry ? upperdentry : stack[0].dentry; - realinode = d_inode(realdentry); - - err = -ENOMEM; - if (upperdentry && !d_is_dir(upperdentry)) { - inode = ovl_get_inode(dentry->d_sb, realinode); - } else { - inode = ovl_new_inode(dentry->d_sb, realinode->i_mode); - if (inode) - ovl_inode_init(inode, realinode, !!upperdentry); - } - if (!inode) - goto out_free_oe; - ovl_copyattr(realdentry->d_inode, inode); - } - - revert_creds(old_cred); - oe->opaque = upperopaque; - oe->__upperdentry = upperdentry; - memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr); - kfree(stack); - dentry->d_fsdata = oe; - d_add(dentry, inode); - - return NULL; - -out_free_oe: - kfree(oe); -out_put: - for (i = 0; i < ctr; i++) - dput(stack[i].dentry); - kfree(stack); -out_put_upper: - dput(upperdentry); -out: - revert_creds(old_cred); - return ERR_PTR(err); -} - -struct file *ovl_path_open(struct path *path, int flags) -{ - return dentry_open(path, flags | O_NOATIME, current_cred()); -} - static void ovl_put_super(struct super_block *sb) { struct ovl_fs *ufs = sb->s_fs_info; @@ -649,7 +179,7 @@ static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) err = vfs_statfs(&path, buf); if (!err) { - buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen); + buf->f_namelen = ofs->namelen; buf->f_type = OVERLAYFS_SUPER_MAGIC; } @@ -674,6 +204,9 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) } if (ufs->config.default_permissions) seq_puts(m, ",default_permissions"); + if (ufs->config.redirect_dir != ovl_redirect_dir_def) + seq_printf(m, ",redirect_dir=%s", + ufs->config.redirect_dir ? "on" : "off"); return 0; } @@ -700,6 +233,8 @@ enum { OPT_UPPERDIR, OPT_WORKDIR, OPT_DEFAULT_PERMISSIONS, + OPT_REDIRECT_DIR_ON, + OPT_REDIRECT_DIR_OFF, OPT_ERR, }; @@ -708,6 +243,8 @@ static const match_table_t ovl_tokens = { {OPT_UPPERDIR, "upperdir=%s"}, {OPT_WORKDIR, "workdir=%s"}, {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, + {OPT_REDIRECT_DIR_ON, "redirect_dir=on"}, + {OPT_REDIRECT_DIR_OFF, "redirect_dir=off"}, {OPT_ERR, NULL} }; @@ -772,6 +309,14 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) config->default_permissions = true; break; + case OPT_REDIRECT_DIR_ON: + config->redirect_dir = true; + break; + + case OPT_REDIRECT_DIR_OFF: + config->redirect_dir = false; + break; + default: pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p); return -EINVAL; @@ -809,12 +354,9 @@ retry: strlen(OVL_WORKDIR_NAME)); if (!IS_ERR(work)) { - struct kstat stat = { - .mode = S_IFDIR | 0, - }; struct iattr attr = { .ia_valid = ATTR_MODE, - .ia_mode = stat.mode, + .ia_mode = S_IFDIR | 0, }; if (work->d_inode) { @@ -828,7 +370,9 @@ retry: goto retry; } - err = ovl_create_real(dir, work, &stat, NULL, NULL, true); + err = ovl_create_real(dir, work, + &(struct cattr){.mode = S_IFDIR | 0}, + NULL, true); if (err) goto out_dput; @@ -903,7 +447,7 @@ static int ovl_mount_dir_noesc(const char *name, struct path *path) pr_err("overlayfs: filesystem on '%s' not supported\n", name); goto out_put; } - if (!S_ISDIR(path->dentry->d_inode->i_mode)) { + if (!d_is_dir(path->dentry)) { pr_err("overlayfs: '%s' not a directory\n", name); goto out_put; } @@ -936,22 +480,33 @@ static int ovl_mount_dir(const char *name, struct path *path) return err; } -static int ovl_lower_dir(const char *name, struct path *path, long *namelen, - int *stack_depth, bool *remote) +static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs, + const char *name) { - int err; struct kstatfs statfs; + int err = vfs_statfs(path, &statfs); + + if (err) + pr_err("overlayfs: statfs failed on '%s'\n", name); + else + ofs->namelen = max(ofs->namelen, statfs.f_namelen); + + return err; +} + +static int ovl_lower_dir(const char *name, struct path *path, + struct ovl_fs *ofs, int *stack_depth, bool *remote) +{ + int err; err = ovl_mount_dir_noesc(name, path); if (err) goto out; - err = vfs_statfs(path, &statfs); - if (err) { - pr_err("overlayfs: statfs failed on '%s'\n", name); + err = ovl_check_namelen(path, ofs, name); + if (err) goto out_put; - } - *namelen = max(*namelen, statfs.f_namelen); + *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); if (ovl_dentry_remote(path->dentry)) @@ -1067,7 +622,7 @@ static int ovl_own_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, void *buffer, size_t size) { - return -EPERM; + return -EOPNOTSUPP; } static int ovl_own_xattr_set(const struct xattr_handler *handler, @@ -1075,7 +630,7 @@ static int ovl_own_xattr_set(const struct xattr_handler *handler, const char *name, const void *value, size_t size, int flags) { - return -EPERM; + return -EOPNOTSUPP; } static int ovl_other_xattr_get(const struct xattr_handler *handler, @@ -1153,6 +708,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) if (!ufs) goto out; + ufs->config.redirect_dir = ovl_redirect_dir_def; err = ovl_parse_opt((char *) data, &ufs->config); if (err) goto out_free_config; @@ -1183,6 +739,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) goto out_put_upperpath; } + err = ovl_check_namelen(&upperpath, ufs, ufs->config.upperdir); + if (err) + goto out_put_upperpath; + err = ovl_mount_dir(ufs->config.workdir, &workpath); if (err) goto out_put_upperpath; @@ -1214,15 +774,16 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) goto out_free_lowertmp; } + err = -ENOMEM; stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL); if (!stack) goto out_free_lowertmp; + err = -EINVAL; lower = lowertmp; for (numlower = 0; numlower < stacklen; numlower++) { - err = ovl_lower_dir(lower, &stack[numlower], - &ufs->lower_namelen, &sb->s_stack_depth, - &remote); + err = ovl_lower_dir(lower, &stack[numlower], ufs, + &sb->s_stack_depth, &remote); if (err) goto out_put_lowerpath; @@ -1324,7 +885,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) sb->s_fs_info = ufs; sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK; - root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR)); + root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); if (!root_dentry) goto out_free_oe; |