[PATCH 3.10 58/71] libceph: do not hard code max auth ticket len

[Greg Kroah-Hartman]

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ilya Dryomov <ilya.dryomov@xxxxxxxxxxx>

commit c27a3e4d667fdcad3db7b104f75659478e0c68d8 upstream.

We hard code cephx auth ticket buffer size to 256 bytes.  This isn't
enough for any moderate setups and, in case tickets themselves are not
encrypted, leads to buffer overflows (ceph_x_decrypt() errors out, but
ceph_decode_copy() doesn't - it's just a memcpy() wrapper).  Since the
buffer is allocated dynamically anyway, allocated it a bit later, at
the point where we know how much is going to be needed.

Fixes: http://tracker.ceph.com/issues/8979

Signed-off-by: Ilya Dryomov <ilya.dryomov@xxxxxxxxxxx>
Reviewed-by: Sage Weil <sage@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/ceph/auth_x.c |   64 ++++++++++++++++++++++++------------------------------
 1 file changed, 29 insertions(+), 35 deletions(-)

--- a/net/ceph/auth_x.c
+++ b/net/ceph/auth_x.c
@@ -13,8 +13,6 @@
 #include "auth_x.h"
 #include "auth_x_protocol.h"
 
-#define TEMP_TICKET_BUF_LEN	256
-
 static void ceph_x_validate_tickets(struct ceph_auth_client *ac, int *pneed);
 
 static int ceph_x_is_authenticated(struct ceph_auth_client *ac)
@@ -64,7 +62,7 @@ static int ceph_x_encrypt(struct ceph_cr
 }
 
 static int ceph_x_decrypt(struct ceph_crypto_key *secret,
-			  void **p, void *end, void *obuf, size_t olen)
+			  void **p, void *end, void **obuf, size_t olen)
 {
 	struct ceph_x_encrypt_header head;
 	size_t head_len = sizeof(head);
@@ -75,8 +73,14 @@ static int ceph_x_decrypt(struct ceph_cr
 		return -EINVAL;
 
 	dout("ceph_x_decrypt len %d\n", len);
-	ret = ceph_decrypt2(secret, &head, &head_len, obuf, &olen,
-			    *p, len);
+	if (*obuf == NULL) {
+		*obuf = kmalloc(len, GFP_NOFS);
+		if (!*obuf)
+			return -ENOMEM;
+		olen = len;
+	}
+
+	ret = ceph_decrypt2(secret, &head, &head_len, *obuf, &olen, *p, len);
 	if (ret)
 		return ret;
 	if (head.struct_v != 1 || le64_to_cpu(head.magic) != CEPHX_ENC_MAGIC)
@@ -131,18 +135,19 @@ static void remove_ticket_handler(struct
 
 static int process_one_ticket(struct ceph_auth_client *ac,
 			      struct ceph_crypto_key *secret,
-			      void **p, void *end,
-			      void *dbuf, void *ticket_buf)
+			      void **p, void *end)
 {
 	struct ceph_x_info *xi = ac->private;
 	int type;
 	u8 tkt_struct_v, blob_struct_v;
 	struct ceph_x_ticket_handler *th;
+	void *dbuf = NULL;
 	void *dp, *dend;
 	int dlen;
 	char is_enc;
 	struct timespec validity;
 	struct ceph_crypto_key old_key;
+	void *ticket_buf = NULL;
 	void *tp, *tpend;
 	struct ceph_timespec new_validity;
 	struct ceph_crypto_key new_session_key;
@@ -167,8 +172,7 @@ static int process_one_ticket(struct cep
 	}
 
 	/* blob for me */
-	dlen = ceph_x_decrypt(secret, p, end, dbuf,
-			      TEMP_TICKET_BUF_LEN);
+	dlen = ceph_x_decrypt(secret, p, end, &dbuf, 0);
 	if (dlen <= 0) {
 		ret = dlen;
 		goto out;
@@ -195,20 +199,25 @@ static int process_one_ticket(struct cep
 
 	/* ticket blob for service */
 	ceph_decode_8_safe(p, end, is_enc, bad);
-	tp = ticket_buf;
 	if (is_enc) {
 		/* encrypted */
 		dout(" encrypted ticket\n");
-		dlen = ceph_x_decrypt(&old_key, p, end, ticket_buf,
-				      TEMP_TICKET_BUF_LEN);
+		dlen = ceph_x_decrypt(&old_key, p, end, &ticket_buf, 0);
 		if (dlen < 0) {
 			ret = dlen;
 			goto out;
 		}
+		tp = ticket_buf;
 		dlen = ceph_decode_32(&tp);
 	} else {
 		/* unencrypted */
 		ceph_decode_32_safe(p, end, dlen, bad);
+		ticket_buf = kmalloc(dlen, GFP_NOFS);
+		if (!ticket_buf) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		tp = ticket_buf;
 		ceph_decode_need(p, end, dlen, bad);
 		ceph_decode_copy(p, ticket_buf, dlen);
 	}
@@ -237,6 +246,8 @@ static int process_one_ticket(struct cep
 	xi->have_keys |= th->service;
 
 out:
+	kfree(ticket_buf);
+	kfree(dbuf);
 	return ret;
 
 bad:
@@ -249,21 +260,10 @@ static int ceph_x_proc_ticket_reply(stru
 				    void *buf, void *end)
 {
 	void *p = buf;
-	char *dbuf;
-	char *ticket_buf;
 	u8 reply_struct_v;
 	u32 num;
 	int ret;
 
-	dbuf = kmalloc(TEMP_TICKET_BUF_LEN, GFP_NOFS);
-	if (!dbuf)
-		return -ENOMEM;
-
-	ret = -ENOMEM;
-	ticket_buf = kmalloc(TEMP_TICKET_BUF_LEN, GFP_NOFS);
-	if (!ticket_buf)
-		goto out_dbuf;
-
 	ceph_decode_8_safe(&p, end, reply_struct_v, bad);
 	if (reply_struct_v != 1)
 		return -EINVAL;
@@ -272,22 +272,15 @@ static int ceph_x_proc_ticket_reply(stru
 	dout("%d tickets\n", num);
 
 	while (num--) {
-		ret = process_one_ticket(ac, secret, &p, end,
-					 dbuf, ticket_buf);
+		ret = process_one_ticket(ac, secret, &p, end);
 		if (ret)
-			goto out;
+			return ret;
 	}
 
-	ret = 0;
-out:
-	kfree(ticket_buf);
-out_dbuf:
-	kfree(dbuf);
-	return ret;
+	return 0;
 
 bad:
-	ret = -EINVAL;
-	goto out;
+	return -EINVAL;
 }
 
 static int ceph_x_build_authorizer(struct ceph_auth_client *ac,
@@ -603,13 +596,14 @@ static int ceph_x_verify_authorizer_repl
 	struct ceph_x_ticket_handler *th;
 	int ret = 0;
 	struct ceph_x_authorize_reply reply;
+	void *preply = &reply;
 	void *p = au->reply_buf;
 	void *end = p + sizeof(au->reply_buf);
 
 	th = get_ticket_handler(ac, au->service);
 	if (IS_ERR(th))
 		return PTR_ERR(th);
-	ret = ceph_x_decrypt(&th->session_key, &p, end, &reply, sizeof(reply));
+	ret = ceph_x_decrypt(&th->session_key, &p, end, &preply, sizeof(reply));
 	if (ret < 0)
 		return ret;
 	if (ret != sizeof(reply))


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