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path: root/fs/overlayfs/super.c
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Diffstat (limited to 'fs/overlayfs/super.c')
-rw-r--r--fs/overlayfs/super.c123
1 files changed, 95 insertions, 28 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 84c5e27fbfd9..7466ff339c66 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -273,11 +273,58 @@ static void ovl_dentry_release(struct dentry *dentry)
}
}
+static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ unsigned int i;
+ int ret = 1;
+
+ for (i = 0; i < oe->numlower; i++) {
+ struct dentry *d = oe->lowerstack[i].dentry;
+
+ if (d->d_flags & DCACHE_OP_REVALIDATE) {
+ ret = d->d_op->d_revalidate(d, flags);
+ if (ret < 0)
+ return ret;
+ if (!ret) {
+ if (!(flags & LOOKUP_RCU))
+ d_invalidate(d);
+ return -ESTALE;
+ }
+ }
+ }
+ return 1;
+}
+
+static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ unsigned int i;
+ int ret = 1;
+
+ for (i = 0; i < oe->numlower; i++) {
+ struct dentry *d = oe->lowerstack[i].dentry;
+
+ if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) {
+ ret = d->d_op->d_weak_revalidate(d, flags);
+ if (ret <= 0)
+ break;
+ }
+ }
+ return ret;
+}
+
static const struct dentry_operations ovl_dentry_operations = {
.d_release = ovl_dentry_release,
.d_select_inode = ovl_d_select_inode,
};
+static const struct dentry_operations ovl_reval_dentry_operations = {
+ .d_release = ovl_dentry_release,
+ .d_revalidate = ovl_dentry_revalidate,
+ .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]);
@@ -289,6 +336,20 @@ static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
return oe;
}
+static bool ovl_dentry_remote(struct dentry *dentry)
+{
+ return dentry->d_flags &
+ (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+}
+
+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,
struct qstr *name)
{
@@ -304,6 +365,10 @@ static inline struct dentry *ovl_lookup_real(struct dentry *dir,
} 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;
}
@@ -351,6 +416,11 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
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;
@@ -530,7 +600,7 @@ static int ovl_remount(struct super_block *sb, int *flags, char *data)
{
struct ovl_fs *ufs = sb->s_fs_info;
- if (!(*flags & MS_RDONLY) && !ufs->upper_mnt)
+ if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt || !ufs->workdir))
return -EROFS;
return 0;
@@ -695,25 +765,6 @@ static void ovl_unescape(char *s)
}
}
-static bool ovl_is_allowed_fs_type(struct dentry *root)
-{
- const struct dentry_operations *dop = root->d_op;
-
- /*
- * We don't support:
- * - automount filesystems
- * - filesystems with revalidate (FIXME for lower layer)
- * - filesystems with case insensitive names
- */
- if (dop &&
- (dop->d_manage || dop->d_automount ||
- dop->d_revalidate || dop->d_weak_revalidate ||
- dop->d_compare || dop->d_hash)) {
- return false;
- }
- return true;
-}
-
static int ovl_mount_dir_noesc(const char *name, struct path *path)
{
int err = -EINVAL;
@@ -728,7 +779,7 @@ static int ovl_mount_dir_noesc(const char *name, struct path *path)
goto out;
}
err = -EINVAL;
- if (!ovl_is_allowed_fs_type(path->dentry)) {
+ if (ovl_dentry_weird(path->dentry)) {
pr_err("overlayfs: filesystem on '%s' not supported\n", name);
goto out_put;
}
@@ -752,13 +803,21 @@ static int ovl_mount_dir(const char *name, struct path *path)
if (tmp) {
ovl_unescape(tmp);
err = ovl_mount_dir_noesc(tmp, path);
+
+ if (!err)
+ if (ovl_dentry_remote(path->dentry)) {
+ pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
+ tmp);
+ path_put(path);
+ err = -EINVAL;
+ }
kfree(tmp);
}
return err;
}
static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
- int *stack_depth)
+ int *stack_depth, bool *remote)
{
int err;
struct kstatfs statfs;
@@ -775,6 +834,9 @@ static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
*namelen = max(*namelen, statfs.f_namelen);
*stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
+ if (ovl_dentry_remote(path->dentry))
+ *remote = true;
+
return 0;
out_put:
@@ -828,6 +890,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
unsigned int numlower;
unsigned int stacklen = 0;
unsigned int i;
+ bool remote = false;
int err;
err = -ENOMEM;
@@ -901,7 +964,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
lower = lowertmp;
for (numlower = 0; numlower < stacklen; numlower++) {
err = ovl_lower_dir(lower, &stack[numlower],
- &ufs->lower_namelen, &sb->s_stack_depth);
+ &ufs->lower_namelen, &sb->s_stack_depth,
+ &remote);
if (err)
goto out_put_lowerpath;
@@ -926,9 +990,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry);
err = PTR_ERR(ufs->workdir);
if (IS_ERR(ufs->workdir)) {
- pr_err("overlayfs: failed to create directory %s/%s\n",
- ufs->config.workdir, OVL_WORKDIR_NAME);
- goto out_put_upper_mnt;
+ pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
+ ufs->config.workdir, OVL_WORKDIR_NAME, -err);
+ sb->s_flags |= MS_RDONLY;
+ ufs->workdir = NULL;
}
}
@@ -958,7 +1023,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
if (!ufs->upper_mnt)
sb->s_flags |= MS_RDONLY;
- sb->s_d_op = &ovl_dentry_operations;
+ if (remote)
+ sb->s_d_op = &ovl_reval_dentry_operations;
+ else
+ sb->s_d_op = &ovl_dentry_operations;
err = -ENOMEM;
oe = ovl_alloc_entry(numlower);
@@ -998,7 +1066,6 @@ out_put_lower_mnt:
kfree(ufs->lower_mnt);
out_put_workdir:
dput(ufs->workdir);
-out_put_upper_mnt:
mntput(ufs->upper_mnt);
out_put_lowerpath:
for (i = 0; i < numlower; i++)
generated by cgit (git 2.34.1) at 2024-05-26 04:35:52 +0000