[PATCH] scsi: target: compare all six ISID bytes when identifying a nexus

[PATCH] scsi: target: compare all six ISID bytes when identifying a nexus

[Ciro Iriarte]

lio_sess_get_initiator_sid() reports the ISID as twelve hex digits, and
iSCSI TransportIDs carry the same digits. __transport_register_session(),
__core_scsi3_do_alloc_registration() and
core_scsi3_alloc_aptpl_registration() turn that text into
sess_bin_isid and pr_reg_bin_isid with get_unaligned_be64(), which takes
the first eight characters, i.e. the first four ISID bytes.

open-iscsi ISIDs start with 00023d00 and differ only in the qualifier in
the last two bytes, so every session of one initiator gets the same
binary ISID. target_scsi2_reservation_check() and
target_scsi3_pr_reservation_check() then treat any session of the
reservation holder's initiator as the holder:

- after RESERVE(6) on one session, another session of the same
  initiator can still write;
- with a Write Exclusive persistent reservation, another session that
  is not registered, or registered but not the holder, can still write.

Reproduced with two open-iscsi sessions (ifaces default and if2) to a
ramdisk LUN: on v6.12.113 every command from the second session
completes with GOOD; with this patch TEST UNIT READY and WRITE(10)
under RESERVE(6), and WRITE(10) under Write Exclusive, return
RESERVATION CONFLICT, and READ(10) is still allowed.

Convert all six bytes. Text that is not exactly twelve hex digits keeps
the old conversion of its first eight characters, now copied into a
zeroed buffer so that a shorter string, such as an initiator_sid written
to res_aptpl_metadata, is not read past its end.

An all-zero ISID now converts to 0, which
target_scsi2_reservation_reserve() took to mean "no ISID". Set
DRF_SPC2_RESERVATIONS_WITH_ISID when the fabric reports ISIDs instead.
Also update the TransportID parser comment that referred to the
get_unaligned_be64() read.

Initiators that relied on the old behaviour, reserving through one
session and writing through another without registering it, will now
see RESERVATION CONFLICT, as SPC requires.

Fixes: e48354ce078c ("iscsi-target: Add iSCSI fabric support for target v4.1")
Cc: stable@vger.kernel.org
Signed-off-by: Ciro Iriarte <ciro.iriarte+software@gmail.com>
---
 drivers/target/target_core_fabric_lib.c |  8 +++---
 drivers/target/target_core_pr.c         | 33 ++++++++++++++++++++++---
 drivers/target/target_core_pr.h         |  1 +
 drivers/target/target_core_transport.c  |  2 +-
 4 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/drivers/target/target_core_fabric_lib.c b/drivers/target/target_core_fabric_lib.c
index ad024009d..f720fbce1 100644
--- a/drivers/target/target_core_fabric_lib.c
+++ b/drivers/target/target_core_fabric_lib.c
@@ -372,10 +372,10 @@ static bool iscsi_parse_pr_out_transport_id(
 			return false;
 		}
 		/*
-		 * The registration code reads the ISID as a C string,
-		 * and its first 8 bytes with get_unaligned_be64(), so
-		 * require 8 bytes after the separator and a NUL inside
-		 * the rest of the descriptor.
+		 * The registration code reads the ISID as a C string, so
+		 * require a NUL inside the rest of the descriptor, and at
+		 * least 8 bytes after the separator: an ISID is twelve hex
+		 * digits.
 		 */
 		if (buf + tid_len - p < 8 || !memchr(p, '\0', buf + tid_len - p)) {
 			pr_err("Incomplete or unterminated ISID in iSCSI Initiator port TransportID\n");
diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c
index ca1a2802a..c59032228 100644
--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c
@@ -19,6 +19,7 @@
 #include <linux/fcntl.h>
 #include <linux/fs.h>
 #include <linux/fs_struct.h>
+#include <linux/hex.h>
 #include <scsi/scsi_proto.h>
 #include <linux/unaligned.h>
 
@@ -30,6 +31,28 @@
 #include "target_core_pr.h"
 #include "target_core_ua.h"
 
+/*
+ * lio_sess_get_initiator_sid() prints the six ISID bytes as twelve hex
+ * digits, and iSCSI TransportIDs carry the same digits.  Convert all six
+ * bytes: reading the first eight digits as a big-endian u64 keeps only the
+ * first four ISID bytes, so two sessions of one initiator that differ only
+ * in the qualifier, the usual case, would compare equal.  Text in any other
+ * format keeps the old conversion of its first eight characters, without
+ * reading past the end of a shorter string.
+ */
+u64 target_isid_to_bin(const char *isid)
+{
+	u8 bin[6];
+	char raw[8] = {};
+
+	if (strnlen(isid, 2 * sizeof(bin) + 1) == 2 * sizeof(bin) &&
+	    !hex2bin(bin, isid, sizeof(bin)))
+		return get_unaligned_be48(bin);
+
+	memcpy(raw, isid, strnlen(isid, sizeof(raw)));
+	return get_unaligned_be64(raw);
+}
+
 /*
  * Used for Specify Initiator Ports Capable Bit (SPEC_I_PT)
  */
@@ -285,7 +308,11 @@ target_scsi2_reservation_reserve(struct se_cmd *cmd)
 
 	dev->reservation_holder = sess;
 	dev->dev_reservation_flags |= DRF_SPC2_RESERVATIONS;
-	if (sess->sess_bin_isid != 0) {
+	/*
+	 * An all-zero ISID converts to 0, so test whether the fabric has
+	 * ISIDs rather than the value.
+	 */
+	if (tpg->se_tpg_tfo->sess_get_initiator_sid) {
 		dev->dev_res_bin_isid = sess->sess_bin_isid;
 		dev->dev_reservation_flags |= DRF_SPC2_RESERVATIONS_WITH_ISID;
 	}
@@ -674,7 +701,7 @@ static struct t10_pr_registration *__core_scsi3_do_alloc_registration(
 	 * save it to the registration now.
 	 */
 	if (isid != NULL) {
-		pr_reg->pr_reg_bin_isid = get_unaligned_be64(isid);
+		pr_reg->pr_reg_bin_isid = target_isid_to_bin(isid);
 		snprintf(pr_reg->pr_reg_isid, PR_REG_ISID_LEN, "%s", isid);
 		pr_reg->isid_present_at_reg = 1;
 	}
@@ -866,7 +893,7 @@ int core_scsi3_alloc_aptpl_registration(
 	 * SCSI Initiator Port, restore it now.
 	 */
 	if (isid != NULL) {
-		pr_reg->pr_reg_bin_isid = get_unaligned_be64(isid);
+		pr_reg->pr_reg_bin_isid = target_isid_to_bin(isid);
 		snprintf(pr_reg->pr_reg_isid, PR_REG_ISID_LEN, "%s", isid);
 		pr_reg->isid_present_at_reg = 1;
 	}
diff --git a/drivers/target/target_core_pr.h b/drivers/target/target_core_pr.h
index b793c9963..4debfe4be 100644
--- a/drivers/target/target_core_pr.h
+++ b/drivers/target/target_core_pr.h
@@ -72,6 +72,7 @@ extern void core_scsi3_free_pr_reg_from_nacl(struct se_device *,
 					     struct se_node_acl *);
 extern void core_scsi3_free_all_registrations(struct se_device *);
 extern unsigned char *core_scsi3_pr_dump_type(int);
+u64 target_isid_to_bin(const char *isid);
 
 extern sense_reason_t target_scsi3_emulate_pr_in(struct se_cmd *);
 extern sense_reason_t target_scsi3_emulate_pr_out(struct se_cmd *);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 927861c30..4629c9343 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -419,7 +419,7 @@ void __transport_register_session(
 			memset(&buf[0], 0, PR_REG_ISID_LEN);
 			se_tpg->se_tpg_tfo->sess_get_initiator_sid(se_sess,
 					&buf[0], PR_REG_ISID_LEN);
-			se_sess->sess_bin_isid = get_unaligned_be64(&buf[0]);
+			se_sess->sess_bin_isid = target_isid_to_bin(buf);
 		}
 
 		spin_lock_irqsave(&se_nacl->nacl_sess_lock, flags);
-- 
2.55.0