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-rw-r--r--fs/overlayfs/super.c563
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;