FAILED: patch "[PATCH] ceph: cap delegated inode count in ceph_parse_deleg_inos()" failed to apply to 5.15-stable tree

PATCH New [email protected] 2 participants 5 messages Sep 3 – Sep 6

Subsystems (2)

Stable branch Ceph client

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[email protected]

author maintainer

2026-09-03 13:46 UTC #0 lore raw

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 4bd3158bd62466d57ed72a3f7bc5f205fedd6919
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026090356-atlantic-hangup-270a@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4bd3158bd62466d57ed72a3f7bc5f205fedd6919 Mon Sep 17 00:00:00 2001
From: Michael Bommarito <[email protected]>
Date: Tue, 7 Jul 2026 14:06:00 -0400
Subject: [PATCH] ceph: cap delegated inode count in ceph_parse_deleg_inos()

ceph_parse_deleg_inos() decodes interval sets of delegated inode numbers from an MDS create-with-delegation reply. For each set it reads a 64-bit start and a 64-bit len with ceph_decode_64_safe(), which only validates that the eight bytes are present in the message, not the value, and then loops over len while inserting entries into s_delegated_inos.

len is fully attacker controlled. A malicious or compromised MDS can send one huge interval, many intervals in one reply, duplicate intervals, or repeated replies that accumulate delegated inodes on the same session. The original code bounded none of these and could spin the insert loop or grow the xarray without limit.

Bound both dimensions with a single enforcement point. Track the number of delegated inodes held by each MDS session in an atomic counter and grow it only in ceph_insert_deleg_ino(), which uses atomic_add_unless() to refuse to push the count past CEPH_MAX_DELEG_INOS. Because that helper is the only place the counter grows, the per-session population can never exceed the cap, so no separate per-session pre-check is needed. The counter is decremented when async create consumes a delegated inode or when an insert fails, incremented when a delegated inode is restored, initialized with the session xarray, and reset when reconnect destroys the xarray.

A per-session cap alone still lets one reply spin the insert loop on duplicate ranges without growing the counter, so also cap the aggregate interval length accepted from a single reply. Together these bound both the loop trip count per reply and the xarray population across replies.

The cap is a fixed, client-chosen constant rather than a value derived from the MDS. mds_client_prealloc_inos is a userspace MDS configuration option; it is never sent to the kernel client on the wire, and a server-supplied bound could not be trusted for a defensive limit in any case. The constant is set well above that option's documented default of 1000 (a generous multiple), so legitimate refill behavior is unaffected while the CPU and xarray memory a malformed delegation stream can consume stays bounded.

Impact: a malicious or compromised Ceph MDS can no longer make a client spin through an unbounded delegated-inode interval or grow one session's delegated-inode xarray without limit.

Cc [email protected]

Fixes d48464878708 ("ceph: decode interval_sets for delegated inos")

Assisted-by Claude:claude-opus-4-8

Signed-off-by Michael Bommarito <[email protected]>

Reviewed-by Viacheslav Dubeyko <[email protected]>

Signed-off-by Ilya Dryomov <[email protected]>

fs/ceph/mds_client.c +53 -6

index 313281197ff4..9925e7e355e8 100644
@@ -619,10 +619,36 @@ static int parse_reply_info_filelock(void **p, void *end,
 
 #define DELEGATED_INO_AVAILABLE		xa_mk_value(1)
 
+static int ceph_insert_deleg_ino(struct ceph_mds_session *s, u64 ino)
+{
+	struct ceph_client *cl = s->s_mdsc->fsc->client;
+	int err;
+
+	/*
+	 * Cap how many delegated inodes a single session may hold. This is
+	 * the only place that grows the count, so atomic_add_unless() bounds
+	 * it at exactly CEPH_MAX_DELEG_INOS; s_num_deleg_inos can never exceed
+	 * that.
+	 */
+	if (!atomic_add_unless(&s->s_num_deleg_inos, 1, CEPH_MAX_DELEG_INOS)) {
+		pr_warn_ratelimited_client(cl,
+			"MDS session already holds %d delegated inodes\n",
+			CEPH_MAX_DELEG_INOS);
+		return -EOVERFLOW;
+	}
+
+	err = xa_insert(&s->s_delegated_inos, ino, DELEGATED_INO_AVAILABLE,
+			GFP_KERNEL);
+	if (err)
+		atomic_dec(&s->s_num_deleg_inos);
+	return err;
+}
+
 static int ceph_parse_deleg_inos(void **p, void *end,
 				 struct ceph_mds_session *s)
 {
 	struct ceph_client *cl = s->s_mdsc->fsc->client;
+	u64 msg_deleg_inos = 0;
 	u32 sets;
 
 	ceph_decode_32_safe(p, end, sets, bad);

@@ -640,16 +666,34 @@ static int ceph_parse_deleg_inos(void **p, void *end,
 				start, len);
 			continue;
 		}
+
+		/*
+		 * Bound the number of inodes one reply may delegate.
+		 * ceph_insert_deleg_ino() separately caps the per-session
+		 * population, so this only has to stop one reply from spinning
+		 * the insert loop under an attacker-controlled len.
+		 */
+		if (len > (u64)CEPH_MAX_DELEG_INOS ||
+		    msg_deleg_inos > (u64)CEPH_MAX_DELEG_INOS - len) {
+			pr_warn_ratelimited_client(cl,
+				"MDS reply delegates too many inodes (have %llu, +%llu, max %d)\n",
+				msg_deleg_inos, len, CEPH_MAX_DELEG_INOS);
+			return -EIO;
+		}
+		msg_deleg_inos += len;
+
 		while (len--) {
-			int err = xa_insert(&s->s_delegated_inos, start++,
-					    DELEGATED_INO_AVAILABLE,
-					    GFP_KERNEL);
+			int err = ceph_insert_deleg_ino(s, start++);
+
 			if (!err) {
 				doutc(cl, "added delegated inode 0x%llx\n", start - 1);
 			} else if (err == -EBUSY) {
 				pr_warn_client(cl,
 					"MDS delegated inode 0x%llx more than once.\n",
 					start - 1);
+			} else if (err == -EOVERFLOW) {
+				/* ceph_insert_deleg_ino() already warned. */
+				return -EIO;
 			} else {
 				return err;
 			}

@@ -667,16 +711,17 @@ u64 ceph_get_deleg_ino(struct ceph_mds_session *s)
 
 	xa_for_each(&s->s_delegated_inos, ino, val) {
 		val = xa_erase(&s->s_delegated_inos, ino);
-		if (val == DELEGATED_INO_AVAILABLE)
+		if (val == DELEGATED_INO_AVAILABLE) {
+			atomic_dec(&s->s_num_deleg_inos);
 			return ino;
+		}
 	}
 	return 0;
 }
 
 int ceph_restore_deleg_ino(struct ceph_mds_session *s, u64 ino)
 {
-	return xa_insert(&s->s_delegated_inos, ino, DELEGATED_INO_AVAILABLE,
-			 GFP_KERNEL);
+	return ceph_insert_deleg_ino(s, ino);
 }
 #else /* BITS_PER_LONG == 64 */
 /*

@@ -1063,6 +1108,7 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
 	INIT_LIST_HEAD(&s->s_waiting);
 	INIT_LIST_HEAD(&s->s_unsafe);
 	xa_init(&s->s_delegated_inos);
+	atomic_set(&s->s_num_deleg_inos, 0);
 	INIT_LIST_HEAD(&s->s_cap_releases);
 	INIT_WORK(&s->s_cap_release_work, ceph_cap_release_work);

@@ -5115,6 +5161,7 @@ static int send_mds_reconnect(struct ceph_mds_client *mdsc,
 
 	/* Serialized by s_mutex against concurrent ceph_get_deleg_ino(). */
 	xa_destroy(&session->s_delegated_inos);
+	atomic_set(&session->s_num_deleg_inos, 0);
 	if (session->s_state == CEPH_MDS_SESSION_CLOSED ||
 	    session->s_state == CEPH_MDS_SESSION_REJECTED) {
 		pr_info_client(cl, "mds%d skipping reconnect, session %s\n",

fs/ceph/mds_client.h +1 -0

index 0ece4c9e3529..3c62e3c3530b 100644
@@ -300,6 +300,7 @@ struct ceph_mds_session {
 	struct list_head  s_waiting;  /* waiting requests */
 	struct list_head  s_unsafe;   /* unsafe requests */
 	struct xarray	  s_delegated_inos;
+	atomic_t	  s_num_deleg_inos;
 };
 
 /*

fs/ceph/super.h +9 -0

index 1d6aab060780..6ce0b771c66b 100644
@@ -641,6 +641,15 @@ static inline int ceph_ino_compare(struct inode *inode, void *data)
 #define CEPH_MDS_INO_LOG_OFFSET		(2 * CEPH_MAX_MDS)
 #define CEPH_INO_SYSTEM_BASE		((6*CEPH_MAX_MDS) + (CEPH_MAX_MDS * CEPH_NUM_STRAY))
 
+/*
+ * Upper bound on the number of delegated inodes a single MDS session may
+ * hold. The MDS normally hands out a small preallocation window (the
+ * userspace mds_client_prealloc_inos option defaults to 1000) and refills
+ * it as the client consumes entries. This leaves generous headroom while
+ * bounding the CPU and memory a malformed delegation interval can consume.
+ */
+#define CEPH_MAX_DELEG_INOS		8192
+
 static inline bool ceph_vino_is_reserved(const struct ceph_vino vino)
 {
 	if (vino.ino >= CEPH_INO_SYSTEM_BASE ||

Sasha Levin

maintainer

2026-09-06 16:25 UTC #1 lore raw

PATCH 1/2 ceph: pass the mdsc to several helpers

From: Xiubo Li <[email protected]>

We will use the 'mdsc' to get the global_id in the following commits.

Link https://tracker.ceph.com/issues/61590

Signed-off-by Xiubo Li <[email protected]>

Reviewed-by Patrick Donnelly <[email protected]>

Reviewed-by Milind Changire <[email protected]>

Signed-off-by Ilya Dryomov <[email protected]>

---
 fs/ceph/caps.c              | 14 ++++---
 fs/ceph/debugfs.c           |  4 +-
 fs/ceph/dir.c               |  2 +-
 fs/ceph/file.c              |  2 +-
 fs/ceph/mds_client.c        | 77 ++++++++++++++++++++++++-------------
 fs/ceph/mds_client.h        |  3 +-
 fs/ceph/mdsmap.c            |  3 +-
 fs/ceph/snap.c              | 21 +++++-----
 fs/ceph/super.h             |  3 +-
 include/linux/ceph/mdsmap.h |  5 ++-
 10 files changed, 85 insertions(+), 49 deletions(-)

fs/ceph/caps.c +8 -6

index bf904dc861a4b..a25c5d8f5c4bd 100644
@@ -1175,7 +1175,8 @@ void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release)
 	}
 }
 
-void ceph_remove_cap(struct ceph_cap *cap, bool queue_release)
+void ceph_remove_cap(struct ceph_mds_client *mdsc, struct ceph_cap *cap,
+		     bool queue_release)
 {
 	struct ceph_inode_info *ci = cap->ci;
 	struct ceph_fs_client *fsc;

@@ -1316,6 +1317,7 @@ static void encode_cap_msg(struct ceph_msg *msg, struct cap_msg_args *arg)
  */
 void __ceph_remove_caps(struct ceph_inode_info *ci)
 {
+	struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(ci->vfs_inode.i_sb);
 	struct rb_node *p;
 
 	/* lock i_ceph_lock, because ceph_d_revalidate(..., LOOKUP_RCU)

@@ -1325,7 +1327,7 @@ void __ceph_remove_caps(struct ceph_inode_info *ci)
 	while (p) {
 		struct ceph_cap *cap = rb_entry(p, struct ceph_cap, ci_node);
 		p = rb_next(p);
-		ceph_remove_cap(cap, true);
+		ceph_remove_cap(mdsc, cap, true);
 	}
 	spin_unlock(&ci->i_ceph_lock);
 }

@@ -3869,7 +3871,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 		goto out_unlock;
 
 	if (target < 0) {
-		ceph_remove_cap(cap, false);
+		ceph_remove_cap(mdsc, cap, false);
 		goto out_unlock;
 	}

@@ -3904,7 +3906,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 				change_auth_cap_ses(ci, tcap->session);
 			}
 		}
-		ceph_remove_cap(cap, false);
+		ceph_remove_cap(mdsc, cap, false);
 		goto out_unlock;
 	} else if (tsession) {
 		/* add placeholder for the export tagert */

@@ -3921,7 +3923,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 			spin_unlock(&mdsc->cap_dirty_lock);
 		}
 
-		ceph_remove_cap(cap, false);
+		ceph_remove_cap(mdsc, cap, false);
 		goto out_unlock;
 	}

@@ -4032,7 +4034,7 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
 					ocap->mseq, mds, le32_to_cpu(ph->seq),
 					le32_to_cpu(ph->mseq));
 		}
-		ceph_remove_cap(ocap, (ph->flags & CEPH_CAP_FLAG_RELEASE));
+		ceph_remove_cap(mdsc, ocap, (ph->flags & CEPH_CAP_FLAG_RELEASE));
 	}
 
 	*old_issued = issued;

fs/ceph/debugfs.c +2 -2

index 38b78b45811f9..44f776c71f427 100644
@@ -81,7 +81,7 @@ static int mdsc_show(struct seq_file *s, void *p)
 		if (req->r_inode) {
 			seq_printf(s, " #%llx", ceph_ino(req->r_inode));
 		} else if (req->r_dentry) {
-			path = ceph_mdsc_build_path(req->r_dentry, &pathlen,
+			path = ceph_mdsc_build_path(mdsc, req->r_dentry, &pathlen,
 						    &pathbase, 0);
 			if (IS_ERR(path))
 				path = NULL;

@@ -100,7 +100,7 @@ static int mdsc_show(struct seq_file *s, void *p)
 		}
 
 		if (req->r_old_dentry) {
-			path = ceph_mdsc_build_path(req->r_old_dentry, &pathlen,
+			path = ceph_mdsc_build_path(mdsc, req->r_old_dentry, &pathlen,
 						    &pathbase, 0);
 			if (IS_ERR(path))
 				path = NULL;

fs/ceph/dir.c +1 -1

index 74845a793aa36..1a0126ae3a44c 100644
@@ -1083,7 +1083,7 @@ static void ceph_async_unlink_cb(struct ceph_mds_client *mdsc,
 	if (result) {
 		int pathlen = 0;
 		u64 base = 0;
-		char *path = ceph_mdsc_build_path(req->r_dentry, &pathlen,
+		char *path = ceph_mdsc_build_path(mdsc, req->r_dentry, &pathlen,
 						  &base, 0);
 
 		/* mark error on parent + clear complete */

fs/ceph/file.c +1 -1

index 7ecb51384497b..95b40b4a1bc60 100644
@@ -531,7 +531,7 @@ static void ceph_async_create_cb(struct ceph_mds_client *mdsc,
 		struct dentry *dentry = req->r_dentry;
 		int pathlen = 0;
 		u64 base = 0;
-		char *path = ceph_mdsc_build_path(req->r_dentry, &pathlen,
+		char *path = ceph_mdsc_build_path(mdsc, req->r_dentry, &pathlen,
 						  &base, 0);
 
 		ceph_dir_clear_complete(req->r_parent);

fs/ceph/mds_client.c +51 ~~-26~~

210 lines not on this page · raw message

fs/ceph/mds_client.h +2 -1

index 4c2741933bf43..df8976aefc5c4 100644
@@ -546,7 +546,8 @@ static inline void ceph_mdsc_free_path(char *path, int len)
 		__putname(path - (PATH_MAX - 1 - len));
 }
 
-extern char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *base,
+extern char *ceph_mdsc_build_path(struct ceph_mds_client *mdsc,
+				  struct dentry *dentry, int *plen, u64 *base,
 				  int stop_on_nosnap);
 
 extern void __ceph_mdsc_drop_dentry_lease(struct dentry *dentry);

fs/ceph/mdsmap.c +2 -1

index 0e869b70a50c1..ce3d99661e96d 100644
@@ -114,7 +114,8 @@ static int __decode_and_drop_compat_set(void **p, void* end)
  * Ignore any fields we don't care about (there are quite a few of
  * them).
  */
-struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end, bool msgr2)
+struct ceph_mdsmap *ceph_mdsmap_decode(struct ceph_mds_client *mdsc, void **p,
+				       void *end, bool msgr2)
 {
 	struct ceph_mdsmap *m;
 	const void *start = *p;

fs/ceph/snap.c +12 -9

index 74a1fc919c6be..f5527960fb521 100644
@@ -319,8 +319,9 @@ static int cmpu64_rev(const void *a, const void *b)
 /*
  * build the snap context for a given realm.
  */
-static int build_snap_context(struct ceph_snap_realm *realm,
-			      struct list_head* dirty_realms)
+static int build_snap_context(struct ceph_mds_client *mdsc,
+			      struct ceph_snap_realm *realm,
+			      struct list_head *dirty_realms)
 {
 	struct ceph_snap_realm *parent = realm->parent;
 	struct ceph_snap_context *snapc;

@@ -334,7 +335,7 @@ static int build_snap_context(struct ceph_snap_realm *realm,
 	 */
 	if (parent) {
 		if (!parent->cached_context) {
-			err = build_snap_context(parent, dirty_realms);
+			err = build_snap_context(mdsc, parent, dirty_realms);
 			if (err)
 				goto fail;
 		}

@@ -417,16 +418,17 @@ static int build_snap_context(struct ceph_snap_realm *realm,
 /*
  * rebuild snap context for the given realm and all of its children.
  */
-static void rebuild_snap_realms(struct ceph_snap_realm *realm,
+static void rebuild_snap_realms(struct ceph_mds_client *mdsc,
+				struct ceph_snap_realm *realm,
 				struct list_head *dirty_realms)
 {
 	struct ceph_snap_realm *child;
 
 	dout("rebuild_snap_realms %llx %p\n", realm->ino, realm);
-	build_snap_context(realm, dirty_realms);
+	build_snap_context(mdsc, realm, dirty_realms);
 
 	list_for_each_entry(child, &realm->children, child_item)
-		rebuild_snap_realms(child, dirty_realms);
+		rebuild_snap_realms(mdsc, child, dirty_realms);
 }

@@ -669,7 +671,8 @@ int __ceph_finish_cap_snap(struct ceph_inode_info *ci,
  * Queue cap_snaps for snap writeback for this realm and its children.
  * Called under snap_rwsem, so realm topology won't change.
  */
-static void queue_realm_cap_snaps(struct ceph_snap_realm *realm)
+static void queue_realm_cap_snaps(struct ceph_mds_client *mdsc,
+				  struct ceph_snap_realm *realm)
 {
 	struct ceph_inode_info *ci;
 	struct inode *lastinode = NULL;

@@ -791,7 +794,7 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
 
 	/* rebuild_snapcs when we reach the _end_ (root) of the trace */
 	if (realm_to_rebuild && p >= e)
-		rebuild_snap_realms(realm_to_rebuild, &dirty_realms);
+		rebuild_snap_realms(mdsc, realm_to_rebuild, &dirty_realms);
 
 	if (!first_realm)
 		first_realm = realm;

@@ -809,7 +812,7 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
 		realm = list_first_entry(&dirty_realms, struct ceph_snap_realm,
 					 dirty_item);
 		list_del_init(&realm->dirty_item);
-		queue_realm_cap_snaps(realm);
+		queue_realm_cap_snaps(mdsc, realm);
 	}
 
 	if (realm_ret)

fs/ceph/super.h +2 -1

index 5e07715b895d1..6c82b4eac46cb 100644
@@ -1140,7 +1140,8 @@ extern void ceph_add_cap(struct inode *inode,
 			 unsigned cap, unsigned seq, u64 realmino, int flags,
 			 struct ceph_cap **new_cap);
 extern void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release);
-extern void ceph_remove_cap(struct ceph_cap *cap, bool queue_release);
+extern void ceph_remove_cap(struct ceph_mds_client *mdsc, struct ceph_cap *cap,
+			    bool queue_release);
 extern void __ceph_remove_caps(struct ceph_inode_info *ci);
 extern void ceph_put_cap(struct ceph_mds_client *mdsc,
 			 struct ceph_cap *cap);

include/linux/ceph/mdsmap.h +4 -1

index 523fd04528562..d5e3ed0487f3e 100644
@@ -5,6 +5,8 @@
 #include <linux/bug.h>
 #include <linux/ceph/types.h>
 
+struct ceph_mds_client;
+
 /*
  * mds map - describe servers in the mds cluster.
  *

@@ -64,7 +66,8 @@ static inline bool ceph_mdsmap_is_laggy(struct ceph_mdsmap *m, int w)
 }
 
 extern int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m);
-struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end, bool msgr2);
+struct ceph_mdsmap *ceph_mdsmap_decode(struct ceph_mds_client *mdsc, void **p,
+				       void *end, bool msgr2);
 extern void ceph_mdsmap_destroy(struct ceph_mdsmap *m);
 extern bool ceph_mdsmap_is_cluster_available(struct ceph_mdsmap *m);

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-09-06 16:25 UTC #2 lore raw

PATCH 2/2 ceph: cap delegated inode count in ceph_parse_deleg_inos()

From: Michael Bommarito <[email protected]>

[ Upstream commit 4bd3158bd62466d57ed72a3f7bc5f205fedd6919 ]

Impact: a malicious or compromised Ceph MDS can no longer make a client spin through an unbounded delegated-inode interval or grow one session's delegated-inode xarray without limit.

Cc [email protected]

Fixes d48464878708 ("ceph: decode interval_sets for delegated inos")

Assisted-by Claude:claude-opus-4-8

Signed-off-by Michael Bommarito <[email protected]>

Reviewed-by Viacheslav Dubeyko <[email protected]>

Signed-off-by Ilya Dryomov <[email protected]>

Signed-off-by Sasha Levin <[email protected]>

---
 fs/ceph/mds_client.c | 59 +++++++++++++++++++++++++++++++++++++++-----
 fs/ceph/mds_client.h |  1 +
 fs/ceph/super.h      |  9 +++++++
 3 files changed, 63 insertions(+), 6 deletions(-)

fs/ceph/mds_client.c +53 -6

index 3092cb14e683c..e20be2e984ec1 100644
@@ -430,10 +430,36 @@ static int parse_reply_info_filelock(void **p, void *end,
 
 #define DELEGATED_INO_AVAILABLE		xa_mk_value(1)
 
+static int ceph_insert_deleg_ino(struct ceph_mds_session *s, u64 ino)
+{
+	struct ceph_client *cl = s->s_mdsc->fsc->client;
+	int err;
+
+	/*
+	 * Cap how many delegated inodes a single session may hold. This is
+	 * the only place that grows the count, so atomic_add_unless() bounds
+	 * it at exactly CEPH_MAX_DELEG_INOS; s_num_deleg_inos can never exceed
+	 * that.
+	 */
+	if (!atomic_add_unless(&s->s_num_deleg_inos, 1, CEPH_MAX_DELEG_INOS)) {
+		pr_warn_ratelimited_client(cl,
+			"MDS session already holds %d delegated inodes\n",
+			CEPH_MAX_DELEG_INOS);
+		return -EOVERFLOW;
+	}
+
+	err = xa_insert(&s->s_delegated_inos, ino, DELEGATED_INO_AVAILABLE,
+			GFP_KERNEL);
+	if (err)
+		atomic_dec(&s->s_num_deleg_inos);
+	return err;
+}
+
 static int ceph_parse_deleg_inos(void **p, void *end,
 				 struct ceph_mds_session *s)
 {
 	struct ceph_client *cl = s->s_mdsc->fsc->client;
+	u64 msg_deleg_inos = 0;
 	u32 sets;
 
 	ceph_decode_32_safe(p, end, sets, bad);

@@ -451,16 +477,34 @@ static int ceph_parse_deleg_inos(void **p, void *end,
 				start, len);
 			continue;
 		}
+
+		/*
+		 * Bound the number of inodes one reply may delegate.
+		 * ceph_insert_deleg_ino() separately caps the per-session
+		 * population, so this only has to stop one reply from spinning
+		 * the insert loop under an attacker-controlled len.
+		 */
+		if (len > (u64)CEPH_MAX_DELEG_INOS ||
+		    msg_deleg_inos > (u64)CEPH_MAX_DELEG_INOS - len) {
+			pr_warn_ratelimited_client(cl,
+				"MDS reply delegates too many inodes (have %llu, +%llu, max %d)\n",
+				msg_deleg_inos, len, CEPH_MAX_DELEG_INOS);
+			return -EIO;
+		}
+		msg_deleg_inos += len;
+
 		while (len--) {
-			int err = xa_insert(&s->s_delegated_inos, start++,
-					    DELEGATED_INO_AVAILABLE,
-					    GFP_KERNEL);
+			int err = ceph_insert_deleg_ino(s, start++);
+
 			if (!err) {
 				doutc(cl, "added delegated inode 0x%llx\n", start - 1);
 			} else if (err == -EBUSY) {
 				pr_warn_client(cl,
 					"MDS delegated inode 0x%llx more than once.\n",
 					start - 1);
+			} else if (err == -EOVERFLOW) {
+				/* ceph_insert_deleg_ino() already warned. */
+				return -EIO;
 			} else {
 				return err;
 			}

@@ -478,16 +522,17 @@ u64 ceph_get_deleg_ino(struct ceph_mds_session *s)
 
 	xa_for_each(&s->s_delegated_inos, ino, val) {
 		val = xa_erase(&s->s_delegated_inos, ino);
-		if (val == DELEGATED_INO_AVAILABLE)
+		if (val == DELEGATED_INO_AVAILABLE) {
+			atomic_dec(&s->s_num_deleg_inos);
 			return ino;
+		}
 	}
 	return 0;
 }
 
 int ceph_restore_deleg_ino(struct ceph_mds_session *s, u64 ino)
 {
-	return xa_insert(&s->s_delegated_inos, ino, DELEGATED_INO_AVAILABLE,
-			 GFP_KERNEL);
+	return ceph_insert_deleg_ino(s, ino);
 }
 #else /* BITS_PER_LONG == 64 */
 /*

@@ -753,6 +798,7 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
 	INIT_LIST_HEAD(&s->s_waiting);
 	INIT_LIST_HEAD(&s->s_unsafe);
 	xa_init(&s->s_delegated_inos);
+	atomic_set(&s->s_num_deleg_inos, 0);
 	INIT_LIST_HEAD(&s->s_cap_releases);
 	INIT_WORK(&s->s_cap_release_work, ceph_cap_release_work);

@@ -4061,6 +4107,7 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
 
 	/* Serialized by s_mutex against concurrent ceph_get_deleg_ino(). */
 	xa_destroy(&session->s_delegated_inos);
+	atomic_set(&session->s_num_deleg_inos, 0);
 	if (session->s_state == CEPH_MDS_SESSION_CLOSED ||
 	    session->s_state == CEPH_MDS_SESSION_REJECTED) {
 		pr_info_client(cl, "mds%d skipping reconnect, session %s\n",

fs/ceph/mds_client.h +1 -0

index df8976aefc5c4..2d5ecff5aa7a7 100644
@@ -209,6 +209,7 @@ struct ceph_mds_session {
 	struct list_head  s_waiting;  /* waiting requests */
 	struct list_head  s_unsafe;   /* unsafe requests */
 	struct xarray	  s_delegated_inos;
+	atomic_t	  s_num_deleg_inos;
 };
 
 /*

fs/ceph/super.h +9 -0

index 6c82b4eac46cb..2477a44ae6544 100644
@@ -545,6 +545,15 @@ static inline int ceph_ino_compare(struct inode *inode, void *data)
 #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))
 
+/*
+ * Upper bound on the number of delegated inodes a single MDS session may
+ * hold. The MDS normally hands out a small preallocation window (the
+ * userspace mds_client_prealloc_inos option defaults to 1000) and refills
+ * it as the client consumes entries. This leaves generous headroom while
+ * bounding the CPU and memory a malformed delegation interval can consume.
+ */
+#define CEPH_MAX_DELEG_INOS		8192
+
 static inline bool ceph_vino_is_reserved(const struct ceph_vino vino)
 {
 	if (vino.ino < CEPH_INO_SYSTEM_BASE &&

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-09-06 16:25 UTC #3 lore raw

PATCH 1/2 ceph: pass the mdsc to several helpers

In reply to [email protected]

From: Xiubo Li <[email protected]>

[ Upstream commit 197b7d792d6aead2e30d4b2c054ffabae2ed73dc ]

We will use the 'mdsc' to get the global_id in the following commits.

Link https://tracker.ceph.com/issues/61590

Signed-off-by Xiubo Li <[email protected]>

Reviewed-by Patrick Donnelly <[email protected]>

Reviewed-by Milind Changire <[email protected]>

Signed-off-by Ilya Dryomov <[email protected]>

Stable-dep-of: 4bd3158bd624 ("ceph: cap delegated inode count in ceph_parse_deleg_inos()")

Signed-off-by Sasha Levin <[email protected]>

---
 fs/ceph/caps.c              | 14 ++++---
 fs/ceph/debugfs.c           |  4 +-
 fs/ceph/dir.c               |  2 +-
 fs/ceph/file.c              |  2 +-
 fs/ceph/mds_client.c        | 77 ++++++++++++++++++++++++-------------
 fs/ceph/mds_client.h        |  3 +-
 fs/ceph/mdsmap.c            |  3 +-
 fs/ceph/snap.c              | 21 +++++-----
 fs/ceph/super.h             |  3 +-
 include/linux/ceph/mdsmap.h |  5 ++-
 10 files changed, 85 insertions(+), 49 deletions(-)

fs/ceph/caps.c +8 -6

index bf904dc861a4b..a25c5d8f5c4bd 100644
@@ -1175,7 +1175,8 @@ void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release)
 	}
 }
 
-void ceph_remove_cap(struct ceph_cap *cap, bool queue_release)
+void ceph_remove_cap(struct ceph_mds_client *mdsc, struct ceph_cap *cap,
+		     bool queue_release)
 {
 	struct ceph_inode_info *ci = cap->ci;
 	struct ceph_fs_client *fsc;

@@ -1316,6 +1317,7 @@ static void encode_cap_msg(struct ceph_msg *msg, struct cap_msg_args *arg)
  */
 void __ceph_remove_caps(struct ceph_inode_info *ci)
 {
+	struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(ci->vfs_inode.i_sb);
 	struct rb_node *p;
 
 	/* lock i_ceph_lock, because ceph_d_revalidate(..., LOOKUP_RCU)

@@ -1325,7 +1327,7 @@ void __ceph_remove_caps(struct ceph_inode_info *ci)
 	while (p) {
 		struct ceph_cap *cap = rb_entry(p, struct ceph_cap, ci_node);
 		p = rb_next(p);
-		ceph_remove_cap(cap, true);
+		ceph_remove_cap(mdsc, cap, true);
 	}
 	spin_unlock(&ci->i_ceph_lock);
 }

@@ -3869,7 +3871,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 		goto out_unlock;
 
 	if (target < 0) {
-		ceph_remove_cap(cap, false);
+		ceph_remove_cap(mdsc, cap, false);
 		goto out_unlock;
 	}

@@ -3904,7 +3906,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 				change_auth_cap_ses(ci, tcap->session);
 			}
 		}
-		ceph_remove_cap(cap, false);
+		ceph_remove_cap(mdsc, cap, false);
 		goto out_unlock;
 	} else if (tsession) {
 		/* add placeholder for the export tagert */

@@ -3921,7 +3923,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 			spin_unlock(&mdsc->cap_dirty_lock);
 		}
 
-		ceph_remove_cap(cap, false);
+		ceph_remove_cap(mdsc, cap, false);
 		goto out_unlock;
 	}

@@ -4032,7 +4034,7 @@ static void handle_cap_import(struct ceph_mds_client *mdsc,
 					ocap->mseq, mds, le32_to_cpu(ph->seq),
 					le32_to_cpu(ph->mseq));
 		}
-		ceph_remove_cap(ocap, (ph->flags & CEPH_CAP_FLAG_RELEASE));
+		ceph_remove_cap(mdsc, ocap, (ph->flags & CEPH_CAP_FLAG_RELEASE));
 	}
 
 	*old_issued = issued;

fs/ceph/debugfs.c +2 -2

index 38b78b45811f9..44f776c71f427 100644
@@ -81,7 +81,7 @@ static int mdsc_show(struct seq_file *s, void *p)
 		if (req->r_inode) {
 			seq_printf(s, " #%llx", ceph_ino(req->r_inode));
 		} else if (req->r_dentry) {
-			path = ceph_mdsc_build_path(req->r_dentry, &pathlen,
+			path = ceph_mdsc_build_path(mdsc, req->r_dentry, &pathlen,
 						    &pathbase, 0);
 			if (IS_ERR(path))
 				path = NULL;

@@ -100,7 +100,7 @@ static int mdsc_show(struct seq_file *s, void *p)
 		}
 
 		if (req->r_old_dentry) {
-			path = ceph_mdsc_build_path(req->r_old_dentry, &pathlen,
+			path = ceph_mdsc_build_path(mdsc, req->r_old_dentry, &pathlen,
 						    &pathbase, 0);
 			if (IS_ERR(path))
 				path = NULL;

fs/ceph/dir.c +1 -1

index 74845a793aa36..1a0126ae3a44c 100644
@@ -1083,7 +1083,7 @@ static void ceph_async_unlink_cb(struct ceph_mds_client *mdsc,
 	if (result) {
 		int pathlen = 0;
 		u64 base = 0;
-		char *path = ceph_mdsc_build_path(req->r_dentry, &pathlen,
+		char *path = ceph_mdsc_build_path(mdsc, req->r_dentry, &pathlen,
 						  &base, 0);
 
 		/* mark error on parent + clear complete */

fs/ceph/file.c +1 -1

index 7ecb51384497b..95b40b4a1bc60 100644
@@ -531,7 +531,7 @@ static void ceph_async_create_cb(struct ceph_mds_client *mdsc,
 		struct dentry *dentry = req->r_dentry;
 		int pathlen = 0;
 		u64 base = 0;
-		char *path = ceph_mdsc_build_path(req->r_dentry, &pathlen,
+		char *path = ceph_mdsc_build_path(mdsc, req->r_dentry, &pathlen,
 						  &base, 0);
 
 		ceph_dir_clear_complete(req->r_parent);

fs/ceph/mds_client.c +51 ~~-26~~

210 lines not on this page · raw message

fs/ceph/mds_client.h +2 -1

index 4c2741933bf43..df8976aefc5c4 100644
@@ -546,7 +546,8 @@ static inline void ceph_mdsc_free_path(char *path, int len)
 		__putname(path - (PATH_MAX - 1 - len));
 }
 
-extern char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *base,
+extern char *ceph_mdsc_build_path(struct ceph_mds_client *mdsc,
+				  struct dentry *dentry, int *plen, u64 *base,
 				  int stop_on_nosnap);
 
 extern void __ceph_mdsc_drop_dentry_lease(struct dentry *dentry);

fs/ceph/mdsmap.c +2 -1

index 0e869b70a50c1..ce3d99661e96d 100644
@@ -114,7 +114,8 @@ static int __decode_and_drop_compat_set(void **p, void* end)
  * Ignore any fields we don't care about (there are quite a few of
  * them).
  */
-struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end, bool msgr2)
+struct ceph_mdsmap *ceph_mdsmap_decode(struct ceph_mds_client *mdsc, void **p,
+				       void *end, bool msgr2)
 {
 	struct ceph_mdsmap *m;
 	const void *start = *p;

fs/ceph/snap.c +12 -9

index 74a1fc919c6be..f5527960fb521 100644
@@ -319,8 +319,9 @@ static int cmpu64_rev(const void *a, const void *b)
 /*
  * build the snap context for a given realm.
  */
-static int build_snap_context(struct ceph_snap_realm *realm,
-			      struct list_head* dirty_realms)
+static int build_snap_context(struct ceph_mds_client *mdsc,
+			      struct ceph_snap_realm *realm,
+			      struct list_head *dirty_realms)
 {
 	struct ceph_snap_realm *parent = realm->parent;
 	struct ceph_snap_context *snapc;

@@ -334,7 +335,7 @@ static int build_snap_context(struct ceph_snap_realm *realm,
 	 */
 	if (parent) {
 		if (!parent->cached_context) {
-			err = build_snap_context(parent, dirty_realms);
+			err = build_snap_context(mdsc, parent, dirty_realms);
 			if (err)
 				goto fail;
 		}

@@ -417,16 +418,17 @@ static int build_snap_context(struct ceph_snap_realm *realm,
 /*
  * rebuild snap context for the given realm and all of its children.
  */
-static void rebuild_snap_realms(struct ceph_snap_realm *realm,
+static void rebuild_snap_realms(struct ceph_mds_client *mdsc,
+				struct ceph_snap_realm *realm,
 				struct list_head *dirty_realms)
 {
 	struct ceph_snap_realm *child;
 
 	dout("rebuild_snap_realms %llx %p\n", realm->ino, realm);
-	build_snap_context(realm, dirty_realms);
+	build_snap_context(mdsc, realm, dirty_realms);
 
 	list_for_each_entry(child, &realm->children, child_item)
-		rebuild_snap_realms(child, dirty_realms);
+		rebuild_snap_realms(mdsc, child, dirty_realms);
 }

@@ -669,7 +671,8 @@ int __ceph_finish_cap_snap(struct ceph_inode_info *ci,
  * Queue cap_snaps for snap writeback for this realm and its children.
  * Called under snap_rwsem, so realm topology won't change.
  */
-static void queue_realm_cap_snaps(struct ceph_snap_realm *realm)
+static void queue_realm_cap_snaps(struct ceph_mds_client *mdsc,
+				  struct ceph_snap_realm *realm)
 {
 	struct ceph_inode_info *ci;
 	struct inode *lastinode = NULL;

@@ -791,7 +794,7 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
 
 	/* rebuild_snapcs when we reach the _end_ (root) of the trace */
 	if (realm_to_rebuild && p >= e)
-		rebuild_snap_realms(realm_to_rebuild, &dirty_realms);
+		rebuild_snap_realms(mdsc, realm_to_rebuild, &dirty_realms);
 
 	if (!first_realm)
 		first_realm = realm;

@@ -809,7 +812,7 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
 		realm = list_first_entry(&dirty_realms, struct ceph_snap_realm,
 					 dirty_item);
 		list_del_init(&realm->dirty_item);
-		queue_realm_cap_snaps(realm);
+		queue_realm_cap_snaps(mdsc, realm);
 	}
 
 	if (realm_ret)

fs/ceph/super.h +2 -1

index 5e07715b895d1..6c82b4eac46cb 100644
@@ -1140,7 +1140,8 @@ extern void ceph_add_cap(struct inode *inode,
 			 unsigned cap, unsigned seq, u64 realmino, int flags,
 			 struct ceph_cap **new_cap);
 extern void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release);
-extern void ceph_remove_cap(struct ceph_cap *cap, bool queue_release);
+extern void ceph_remove_cap(struct ceph_mds_client *mdsc, struct ceph_cap *cap,
+			    bool queue_release);
 extern void __ceph_remove_caps(struct ceph_inode_info *ci);
 extern void ceph_put_cap(struct ceph_mds_client *mdsc,
 			 struct ceph_cap *cap);

include/linux/ceph/mdsmap.h +4 -1

index 523fd04528562..d5e3ed0487f3e 100644
@@ -5,6 +5,8 @@
 #include <linux/bug.h>
 #include <linux/ceph/types.h>
 
+struct ceph_mds_client;
+
 /*
  * mds map - describe servers in the mds cluster.
  *

@@ -64,7 +66,8 @@ static inline bool ceph_mdsmap_is_laggy(struct ceph_mdsmap *m, int w)
 }
 
 extern int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m);
-struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end, bool msgr2);
+struct ceph_mdsmap *ceph_mdsmap_decode(struct ceph_mds_client *mdsc, void **p,
+				       void *end, bool msgr2);
 extern void ceph_mdsmap_destroy(struct ceph_mdsmap *m);
 extern bool ceph_mdsmap_is_cluster_available(struct ceph_mdsmap *m);

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-09-06 16:25 UTC #4 lore raw

PATCH 2/2 ceph: cap delegated inode count in ceph_parse_deleg_inos()

From: Michael Bommarito <[email protected]>

[ Upstream commit 4bd3158bd62466d57ed72a3f7bc5f205fedd6919 ]

Impact: a malicious or compromised Ceph MDS can no longer make a client spin through an unbounded delegated-inode interval or grow one session's delegated-inode xarray without limit.

Cc [email protected]

Fixes d48464878708 ("ceph: decode interval_sets for delegated inos")

Assisted-by Claude:claude-opus-4-8

Signed-off-by Michael Bommarito <[email protected]>

Reviewed-by Viacheslav Dubeyko <[email protected]>

Signed-off-by Ilya Dryomov <[email protected]>

Signed-off-by Sasha Levin <[email protected]>

---
 fs/ceph/mds_client.c | 59 +++++++++++++++++++++++++++++++++++++++-----
 fs/ceph/mds_client.h |  1 +
 fs/ceph/super.h      |  9 +++++++
 3 files changed, 63 insertions(+), 6 deletions(-)

fs/ceph/mds_client.c +53 -6

index 3092cb14e683c..e20be2e984ec1 100644
@@ -430,10 +430,36 @@ static int parse_reply_info_filelock(void **p, void *end,
 
 #define DELEGATED_INO_AVAILABLE		xa_mk_value(1)
 
+static int ceph_insert_deleg_ino(struct ceph_mds_session *s, u64 ino)
+{
+	struct ceph_client *cl = s->s_mdsc->fsc->client;
+	int err;
+
+	/*
+	 * Cap how many delegated inodes a single session may hold. This is
+	 * the only place that grows the count, so atomic_add_unless() bounds
+	 * it at exactly CEPH_MAX_DELEG_INOS; s_num_deleg_inos can never exceed
+	 * that.
+	 */
+	if (!atomic_add_unless(&s->s_num_deleg_inos, 1, CEPH_MAX_DELEG_INOS)) {
+		pr_warn_ratelimited_client(cl,
+			"MDS session already holds %d delegated inodes\n",
+			CEPH_MAX_DELEG_INOS);
+		return -EOVERFLOW;
+	}
+
+	err = xa_insert(&s->s_delegated_inos, ino, DELEGATED_INO_AVAILABLE,
+			GFP_KERNEL);
+	if (err)
+		atomic_dec(&s->s_num_deleg_inos);
+	return err;
+}
+
 static int ceph_parse_deleg_inos(void **p, void *end,
 				 struct ceph_mds_session *s)
 {
 	struct ceph_client *cl = s->s_mdsc->fsc->client;
+	u64 msg_deleg_inos = 0;
 	u32 sets;
 
 	ceph_decode_32_safe(p, end, sets, bad);

@@ -451,16 +477,34 @@ static int ceph_parse_deleg_inos(void **p, void *end,
 				start, len);
 			continue;
 		}
+
+		/*
+		 * Bound the number of inodes one reply may delegate.
+		 * ceph_insert_deleg_ino() separately caps the per-session
+		 * population, so this only has to stop one reply from spinning
+		 * the insert loop under an attacker-controlled len.
+		 */
+		if (len > (u64)CEPH_MAX_DELEG_INOS ||
+		    msg_deleg_inos > (u64)CEPH_MAX_DELEG_INOS - len) {
+			pr_warn_ratelimited_client(cl,
+				"MDS reply delegates too many inodes (have %llu, +%llu, max %d)\n",
+				msg_deleg_inos, len, CEPH_MAX_DELEG_INOS);
+			return -EIO;
+		}
+		msg_deleg_inos += len;
+
 		while (len--) {
-			int err = xa_insert(&s->s_delegated_inos, start++,
-					    DELEGATED_INO_AVAILABLE,
-					    GFP_KERNEL);
+			int err = ceph_insert_deleg_ino(s, start++);
+
 			if (!err) {
 				doutc(cl, "added delegated inode 0x%llx\n", start - 1);
 			} else if (err == -EBUSY) {
 				pr_warn_client(cl,
 					"MDS delegated inode 0x%llx more than once.\n",
 					start - 1);
+			} else if (err == -EOVERFLOW) {
+				/* ceph_insert_deleg_ino() already warned. */
+				return -EIO;
 			} else {
 				return err;
 			}

@@ -478,16 +522,17 @@ u64 ceph_get_deleg_ino(struct ceph_mds_session *s)
 
 	xa_for_each(&s->s_delegated_inos, ino, val) {
 		val = xa_erase(&s->s_delegated_inos, ino);
-		if (val == DELEGATED_INO_AVAILABLE)
+		if (val == DELEGATED_INO_AVAILABLE) {
+			atomic_dec(&s->s_num_deleg_inos);
 			return ino;
+		}
 	}
 	return 0;
 }
 
 int ceph_restore_deleg_ino(struct ceph_mds_session *s, u64 ino)
 {
-	return xa_insert(&s->s_delegated_inos, ino, DELEGATED_INO_AVAILABLE,
-			 GFP_KERNEL);
+	return ceph_insert_deleg_ino(s, ino);
 }
 #else /* BITS_PER_LONG == 64 */
 /*

@@ -753,6 +798,7 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
 	INIT_LIST_HEAD(&s->s_waiting);
 	INIT_LIST_HEAD(&s->s_unsafe);
 	xa_init(&s->s_delegated_inos);
+	atomic_set(&s->s_num_deleg_inos, 0);
 	INIT_LIST_HEAD(&s->s_cap_releases);
 	INIT_WORK(&s->s_cap_release_work, ceph_cap_release_work);

@@ -4061,6 +4107,7 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
 
 	/* Serialized by s_mutex against concurrent ceph_get_deleg_ino(). */
 	xa_destroy(&session->s_delegated_inos);
+	atomic_set(&session->s_num_deleg_inos, 0);
 	if (session->s_state == CEPH_MDS_SESSION_CLOSED ||
 	    session->s_state == CEPH_MDS_SESSION_REJECTED) {
 		pr_info_client(cl, "mds%d skipping reconnect, session %s\n",

fs/ceph/mds_client.h +1 -0

index df8976aefc5c4..2d5ecff5aa7a7 100644
@@ -209,6 +209,7 @@ struct ceph_mds_session {
 	struct list_head  s_waiting;  /* waiting requests */
 	struct list_head  s_unsafe;   /* unsafe requests */
 	struct xarray	  s_delegated_inos;
+	atomic_t	  s_num_deleg_inos;
 };
 
 /*

fs/ceph/super.h +9 -0

index 6c82b4eac46cb..2477a44ae6544 100644
@@ -545,6 +545,15 @@ static inline int ceph_ino_compare(struct inode *inode, void *data)
 #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))
 
+/*
+ * Upper bound on the number of delegated inodes a single MDS session may
+ * hold. The MDS normally hands out a small preallocation window (the
+ * userspace mds_client_prealloc_inos option defaults to 1000) and refills
+ * it as the client consumes entries. This leaves generous headroom while
+ * bounding the CPU and memory a malformed delegation interval can consume.
+ */
+#define CEPH_MAX_DELEG_INOS		8192
+
 static inline bool ceph_vino_is_reserved(const struct ceph_vino vino)
 {
 	if (vino.ino < CEPH_INO_SYSTEM_BASE &&

Signature · 1 line

2.53.0