--- /dev/null
+From 3a761d72fa62eec8913e45d29375344f61706541 Mon Sep 17 00:00:00 2001
+From: Christian Brauner <brauner@kernel.org>
+Date: Mon, 4 Apr 2022 12:51:41 +0200
+Subject: exportfs: support idmapped mounts
+
+From: Christian Brauner <brauner@kernel.org>
+
+commit 3a761d72fa62eec8913e45d29375344f61706541 upstream.
+
+Make the two locations where exportfs helpers check permission to lookup
+a given inode idmapped mount aware by switching it to the lookup_one()
+helper. This is a bugfix for the open_by_handle_at() system call which
+doesn't take idmapped mounts into account currently. It's not tied to a
+specific commit so we'll just Cc stable.
+
+In addition this is required to support idmapped base layers in overlay.
+The overlay filesystem uses exportfs to encode and decode file handles
+for its index=on mount option and when nfs_export=on.
+
+Cc: <stable@vger.kernel.org>
+Cc: <linux-fsdevel@vger.kernel.org>
+Tested-by: Giuseppe Scrivano <gscrivan@redhat.com>
+Reviewed-by: Amir Goldstein <amir73il@gmail.com>
+Reviewed-by: Christoph Hellwig <hch@lst.de>
+Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
+Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/exportfs/expfs.c | 5 +++--
+ 1 file changed, 3 insertions(+), 2 deletions(-)
+
+--- a/fs/exportfs/expfs.c
++++ b/fs/exportfs/expfs.c
+@@ -145,7 +145,7 @@ static struct dentry *reconnect_one(stru
+ if (err)
+ goto out_err;
+ dprintk("%s: found name: %s\n", __func__, nbuf);
+- tmp = lookup_one_len_unlocked(nbuf, parent, strlen(nbuf));
++ tmp = lookup_one_unlocked(mnt_user_ns(mnt), nbuf, parent, strlen(nbuf));
+ if (IS_ERR(tmp)) {
+ dprintk("%s: lookup failed: %d\n", __func__, PTR_ERR(tmp));
+ err = PTR_ERR(tmp);
+@@ -525,7 +525,8 @@ exportfs_decode_fh_raw(struct vfsmount *
+ }
+
+ inode_lock(target_dir->d_inode);
+- nresult = lookup_one_len(nbuf, target_dir, strlen(nbuf));
++ nresult = lookup_one(mnt_user_ns(mnt), nbuf,
++ target_dir, strlen(nbuf));
+ if (!IS_ERR(nresult)) {
+ if (unlikely(nresult->d_inode != result->d_inode)) {
+ dput(nresult);
--- /dev/null
+From 00675017e0aeba5305665c52ded4ddce6a4c0231 Mon Sep 17 00:00:00 2001
+From: Christian Brauner <brauner@kernel.org>
+Date: Mon, 4 Apr 2022 12:51:40 +0200
+Subject: fs: add two trivial lookup helpers
+
+From: Christian Brauner <brauner@kernel.org>
+
+commit 00675017e0aeba5305665c52ded4ddce6a4c0231 upstream.
+
+Similar to the addition of lookup_one() add a version of
+lookup_one_unlocked() and lookup_one_positive_unlocked() that take
+idmapped mounts into account. This is required to port overlay to
+support idmapped base layers.
+
+Cc: <linux-fsdevel@vger.kernel.org>
+Tested-by: Giuseppe Scrivano <gscrivan@redhat.com>
+Reviewed-by: Amir Goldstein <amir73il@gmail.com>
+Reviewed-by: Christoph Hellwig <hch@lst.de>
+Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
+Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/namei.c | 70 ++++++++++++++++++++++++++++++++++++++++++--------
+ include/linux/namei.h | 6 ++++
+ 2 files changed, 66 insertions(+), 10 deletions(-)
+
+--- a/fs/namei.c
++++ b/fs/namei.c
+@@ -2718,7 +2718,8 @@ struct dentry *lookup_one(struct user_na
+ EXPORT_SYMBOL(lookup_one);
+
+ /**
+- * lookup_one_len_unlocked - filesystem helper to lookup single pathname component
++ * lookup_one_unlocked - filesystem helper to lookup single pathname component
++ * @mnt_userns: idmapping of the mount the lookup is performed from
+ * @name: pathname component to lookup
+ * @base: base directory to lookup from
+ * @len: maximum length @len should be interpreted to
+@@ -2729,14 +2730,15 @@ EXPORT_SYMBOL(lookup_one);
+ * Unlike lookup_one_len, it should be called without the parent
+ * i_mutex held, and will take the i_mutex itself if necessary.
+ */
+-struct dentry *lookup_one_len_unlocked(const char *name,
+- struct dentry *base, int len)
++struct dentry *lookup_one_unlocked(struct user_namespace *mnt_userns,
++ const char *name, struct dentry *base,
++ int len)
+ {
+ struct qstr this;
+ int err;
+ struct dentry *ret;
+
+- err = lookup_one_common(&init_user_ns, name, base, len, &this);
++ err = lookup_one_common(mnt_userns, name, base, len, &this);
+ if (err)
+ return ERR_PTR(err);
+
+@@ -2745,6 +2747,59 @@ struct dentry *lookup_one_len_unlocked(c
+ ret = lookup_slow(&this, base, 0);
+ return ret;
+ }
++EXPORT_SYMBOL(lookup_one_unlocked);
++
++/**
++ * lookup_one_positive_unlocked - filesystem helper to lookup single
++ * pathname component
++ * @mnt_userns: idmapping of the mount the lookup is performed from
++ * @name: pathname component to lookup
++ * @base: base directory to lookup from
++ * @len: maximum length @len should be interpreted to
++ *
++ * This helper will yield ERR_PTR(-ENOENT) on negatives. The helper returns
++ * known positive or ERR_PTR(). This is what most of the users want.
++ *
++ * Note that pinned negative with unlocked parent _can_ become positive at any
++ * time, so callers of lookup_one_unlocked() need to be very careful; pinned
++ * positives have >d_inode stable, so this one avoids such problems.
++ *
++ * Note that this routine is purely a helper for filesystem usage and should
++ * not be called by generic code.
++ *
++ * The helper should be called without i_mutex held.
++ */
++struct dentry *lookup_one_positive_unlocked(struct user_namespace *mnt_userns,
++ const char *name,
++ struct dentry *base, int len)
++{
++ struct dentry *ret = lookup_one_unlocked(mnt_userns, name, base, len);
++
++ if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) {
++ dput(ret);
++ ret = ERR_PTR(-ENOENT);
++ }
++ return ret;
++}
++EXPORT_SYMBOL(lookup_one_positive_unlocked);
++
++/**
++ * lookup_one_len_unlocked - filesystem helper to lookup single pathname component
++ * @name: pathname component to lookup
++ * @base: base directory to lookup from
++ * @len: maximum length @len should be interpreted to
++ *
++ * Note that this routine is purely a helper for filesystem usage and should
++ * not be called by generic code.
++ *
++ * Unlike lookup_one_len, it should be called without the parent
++ * i_mutex held, and will take the i_mutex itself if necessary.
++ */
++struct dentry *lookup_one_len_unlocked(const char *name,
++ struct dentry *base, int len)
++{
++ return lookup_one_unlocked(&init_user_ns, name, base, len);
++}
+ EXPORT_SYMBOL(lookup_one_len_unlocked);
+
+ /*
+@@ -2758,12 +2813,7 @@ EXPORT_SYMBOL(lookup_one_len_unlocked);
+ struct dentry *lookup_positive_unlocked(const char *name,
+ struct dentry *base, int len)
+ {
+- struct dentry *ret = lookup_one_len_unlocked(name, base, len);
+- if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) {
+- dput(ret);
+- ret = ERR_PTR(-ENOENT);
+- }
+- return ret;
++ return lookup_one_positive_unlocked(&init_user_ns, name, base, len);
+ }
+ EXPORT_SYMBOL(lookup_positive_unlocked);
+
+--- a/include/linux/namei.h
++++ b/include/linux/namei.h
+@@ -69,6 +69,12 @@ extern struct dentry *lookup_one_len(con
+ extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
+ extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int);
+ struct dentry *lookup_one(struct user_namespace *, const char *, struct dentry *, int);
++struct dentry *lookup_one_unlocked(struct user_namespace *mnt_userns,
++ const char *name, struct dentry *base,
++ int len);
++struct dentry *lookup_one_positive_unlocked(struct user_namespace *mnt_userns,
++ const char *name,
++ struct dentry *base, int len);
+
+ extern int follow_down_one(struct path *);
+ extern int follow_down(struct path *);
projects / thirdparty / kernel / stable-queue.git / commitdiff
