This is a note to let you know that I've just added the patch titled
ceph: don't allow access to MDS-private inodes
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ceph-don-t-allow-access-to-mds-private-inodes.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7cfb7091aa64ecb0ff830eae4f231d9ea3cbe9e7
Author: Jeff Layton <jlayton@xxxxxxxxxx>
Date: Thu Apr 1 13:55:11 2021 -0400
ceph: don't allow access to MDS-private inodes
[ Upstream commit d4f6b31d721779d91b5e2f8072478af73b196c34 ]
The MDS reserves a set of inodes for its own usage, and these should
never be accessible to clients. Add a new helper to vet a proposed
inode number against that range, and complain loudly and refuse to
create or look it up if it's in it.
Also, ensure that the MDS doesn't try to delegate inodes that are in
that range or lower. Print a warning if it does, and don't save the
range in the xarray.
URL: https://tracker.ceph.com/issues/49922
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Reviewed-by: Xiubo Li <xiubli@xxxxxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/ceph/export.c b/fs/ceph/export.c
index baa6368bece5..042bb4a02c0a 100644
--- a/fs/ceph/export.c
+++ b/fs/ceph/export.c
@@ -129,6 +129,10 @@ static struct inode *__lookup_inode(struct super_block *sb, u64 ino)
vino.ino = ino;
vino.snap = CEPH_NOSNAP;
+
+ if (ceph_vino_is_reserved(vino))
+ return ERR_PTR(-ESTALE);
+
inode = ceph_find_inode(sb, vino);
if (!inode) {
struct ceph_mds_request *req;
@@ -214,6 +218,10 @@ static struct dentry *__snapfh_to_dentry(struct super_block *sb,
vino.ino = sfh->ino;
vino.snap = sfh->snapid;
}
+
+ if (ceph_vino_is_reserved(vino))
+ return ERR_PTR(-ESTALE);
+
inode = ceph_find_inode(sb, vino);
if (inode)
return d_obtain_alias(inode);
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 790433cb849e..346fcdfcd3e9 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -56,6 +56,9 @@ struct inode *ceph_get_inode(struct super_block *sb, struct ceph_vino vino)
{
struct inode *inode;
+ if (ceph_vino_is_reserved(vino))
+ return ERR_PTR(-EREMOTEIO);
+
inode = iget5_locked(sb, (unsigned long)vino.ino, ceph_ino_compare,
ceph_set_ino_cb, &vino);
if (!inode)
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 8f1d7500a7ec..d560752b764d 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -433,6 +433,13 @@ static int ceph_parse_deleg_inos(void **p, void *end,
ceph_decode_64_safe(p, end, start, bad);
ceph_decode_64_safe(p, end, len, bad);
+
+ /* Don't accept a delegation of system inodes */
+ if (start < CEPH_INO_SYSTEM_BASE) {
+ pr_warn_ratelimited("ceph: ignoring reserved inode range delegation (start=0x%llx len=0x%llx)\n",
+ start, len);
+ continue;
+ }
while (len--) {
int err = xa_insert(&s->s_delegated_inos, ino = start++,
DELEGATED_INO_AVAILABLE,
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 482473e4cce1..c33f744a8e11 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -529,10 +529,34 @@ static inline int ceph_ino_compare(struct inode *inode, void *data)
ci->i_vino.snap == pvino->snap;
}
+/*
+ * The MDS reserves a set of inodes for its own usage. These should never
+ * be accessible by clients, and so the MDS has no reason to ever hand these
+ * out. The range is CEPH_MDS_INO_MDSDIR_OFFSET..CEPH_INO_SYSTEM_BASE.
+ *
+ * These come from src/mds/mdstypes.h in the ceph sources.
+ */
+#define CEPH_MAX_MDS 0x100
+#define CEPH_NUM_STRAY 10
+#define CEPH_MDS_INO_MDSDIR_OFFSET (1 * CEPH_MAX_MDS)
+#define CEPH_INO_SYSTEM_BASE ((6*CEPH_MAX_MDS) + (CEPH_MAX_MDS * CEPH_NUM_STRAY))
+
+static inline bool ceph_vino_is_reserved(const struct ceph_vino vino)
+{
+ if (vino.ino < CEPH_INO_SYSTEM_BASE &&
+ vino.ino >= CEPH_MDS_INO_MDSDIR_OFFSET) {
+ WARN_RATELIMIT(1, "Attempt to access reserved inode number 0x%llx", vino.ino);
+ return true;
+ }
+ return false;
+}
static inline struct inode *ceph_find_inode(struct super_block *sb,
struct ceph_vino vino)
{
+ if (ceph_vino_is_reserved(vino))
+ return NULL;
+
/*
* NB: The hashval will be run through the fs/inode.c hash function
* anyway, so there is no need to squash the inode number down to
