PCI: hotplug: Constify hotplug_slot_ops

Hotplug drivers cannot declare their hotplug_slot_ops const, making them
attractive targets for attackers, because upon registration of a hotplug
slot, __pci_hp_initialize() writes to the "owner" and "mod_name" members
in that struct.

Fix by moving these members to struct hotplug_slot and constify every
driver's hotplug_slot_ops except for pciehp.

pciehp constructs its hotplug_slot_ops at runtime based on the PCIe
port's capabilities, hence cannot declare them const.  It can be
converted to __write_rarely once that's mainlined:
http://www.openwall.com/lists/kernel-hardening/2016/11/16/3

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>  # drivers/pci/hotplug/rpa*
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> # drivers/platform/x86
Cc: Len Brown <lenb@kernel.org>
Cc: Scott Murray <scott@spiteful.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Oliver OHalloran <oliveroh@au1.ibm.com>
Cc: Gavin Shan <gwshan@linux.vnet.ibm.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Corentin Chary <corentin.chary@gmail.com>
Cc: Darren Hart <dvhart@infradead.org>

12 files changed, 25 insertions, 24 deletions

diff --git a/drivers/pci/hotplug/acpiphp_core.c b/drivers/pci/hotplug/acpiphp_core.c
index ad32ffbc4b91..e883cef0f3bc 100644
--- a/drivers/pci/hotplug/acpiphp_core.c
+++ b/drivers/pci/hotplug/acpiphp_core.c
@@ -57,7 +57,7 @@ static int get_attention_status(struct hotplug_slot *slot, u8 *value);
 static int get_latch_status(struct hotplug_slot *slot, u8 *value);
 static int get_adapter_status(struct hotplug_slot *slot, u8 *value);
 
-static struct hotplug_slot_ops acpi_hotplug_slot_ops = {
+static const struct hotplug_slot_ops acpi_hotplug_slot_ops = {
 	.enable_slot		= enable_slot,
 	.disable_slot		= disable_slot,
 	.set_attention_status	= set_attention_status,
diff --git a/drivers/pci/hotplug/cpci_hotplug_core.c b/drivers/pci/hotplug/cpci_hotplug_core.c
index 52a339baf06c..97c32e4c74c8 100644
--- a/drivers/pci/hotplug/cpci_hotplug_core.c
+++ b/drivers/pci/hotplug/cpci_hotplug_core.c
@@ -57,7 +57,7 @@ static int get_attention_status(struct hotplug_slot *slot, u8 *value);
 static int get_adapter_status(struct hotplug_slot *slot, u8 *value);
 static int get_latch_status(struct hotplug_slot *slot, u8 *value);
 
-static struct hotplug_slot_ops cpci_hotplug_slot_ops = {
+static const struct hotplug_slot_ops cpci_hotplug_slot_ops = {
 	.enable_slot = enable_slot,
 	.disable_slot = disable_slot,
 	.set_attention_status = set_attention_status,
diff --git a/drivers/pci/hotplug/cpqphp_core.c b/drivers/pci/hotplug/cpqphp_core.c
index 5a06636e910a..3409b62fceac 100644
--- a/drivers/pci/hotplug/cpqphp_core.c
+++ b/drivers/pci/hotplug/cpqphp_core.c
@@ -560,7 +560,7 @@ static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
 	return 0;
 }
 
-static struct hotplug_slot_ops cpqphp_hotplug_slot_ops = {
+static const struct hotplug_slot_ops cpqphp_hotplug_slot_ops = {
 	.set_attention_status =	set_attention_status,
 	.enable_slot =		process_SI,
 	.disable_slot =		process_SS,
diff --git a/drivers/pci/hotplug/ibmphp.h b/drivers/pci/hotplug/ibmphp.h
index fddb78606c74..db387e10581e 100644
--- a/drivers/pci/hotplug/ibmphp.h
+++ b/drivers/pci/hotplug/ibmphp.h
@@ -740,7 +740,7 @@ int ibmphp_do_disable_slot(struct slot *slot_cur);
 int ibmphp_update_slot_info(struct slot *);	/* This function is called from HPC, so we need it to not be be static */
 int ibmphp_configure_card(struct pci_func *, u8);
 int ibmphp_unconfigure_card(struct slot **, int);
-extern struct hotplug_slot_ops ibmphp_hotplug_slot_ops;
+extern const struct hotplug_slot_ops ibmphp_hotplug_slot_ops;
 
 #endif				//__IBMPHP_H
 
diff --git a/drivers/pci/hotplug/ibmphp_core.c b/drivers/pci/hotplug/ibmphp_core.c
index 4ea57e9019f1..b82fdc17040d 100644
--- a/drivers/pci/hotplug/ibmphp_core.c
+++ b/drivers/pci/hotplug/ibmphp_core.c
@@ -1259,7 +1259,7 @@ error:
 	goto exit;
 }
 
-struct hotplug_slot_ops ibmphp_hotplug_slot_ops = {
+const struct hotplug_slot_ops ibmphp_hotplug_slot_ops = {
 	.set_attention_status =		set_attention_status,
 	.enable_slot =			enable_slot,
 	.disable_slot =			ibmphp_disable_slot,
diff --git a/drivers/pci/hotplug/pci_hotplug_core.c b/drivers/pci/hotplug/pci_hotplug_core.c
index 90fde5f106d8..ede2ed6f4ce0 100644
--- a/drivers/pci/hotplug/pci_hotplug_core.c
+++ b/drivers/pci/hotplug/pci_hotplug_core.c
@@ -49,15 +49,15 @@ static DEFINE_MUTEX(pci_hp_mutex);
 #define GET_STATUS(name, type)	\
 static int get_##name(struct hotplug_slot *slot, type *value)		\
 {									\
-	struct hotplug_slot_ops *ops = slot->ops;			\
+	const struct hotplug_slot_ops *ops = slot->ops;			\
 	int retval = 0;							\
-	if (!try_module_get(ops->owner))				\
+	if (!try_module_get(slot->owner))				\
 		return -ENODEV;						\
 	if (ops->get_##name)						\
 		retval = ops->get_##name(slot, value);			\
 	else								\
 		*value = slot->info->name;				\
-	module_put(ops->owner);						\
+	module_put(slot->owner);					\
 	return retval;							\
 }
 
@@ -90,7 +90,7 @@ static ssize_t power_write_file(struct pci_slot *pci_slot, const char *buf,
 	power = (u8)(lpower & 0xff);
 	dbg("power = %d\n", power);
 
-	if (!try_module_get(slot->ops->owner)) {
+	if (!try_module_get(slot->owner)) {
 		retval = -ENODEV;
 		goto exit;
 	}
@@ -109,7 +109,7 @@ static ssize_t power_write_file(struct pci_slot *pci_slot, const char *buf,
 		err("Illegal value specified for power\n");
 		retval = -EINVAL;
 	}
-	module_put(slot->ops->owner);
+	module_put(slot->owner);
 
 exit:
 	if (retval)
@@ -138,7 +138,8 @@ static ssize_t attention_read_file(struct pci_slot *pci_slot, char *buf)
 static ssize_t attention_write_file(struct pci_slot *pci_slot, const char *buf,
 				    size_t count)
 {
-	struct hotplug_slot_ops *ops = pci_slot->hotplug->ops;
+	struct hotplug_slot *slot = pci_slot->hotplug;
+	const struct hotplug_slot_ops *ops = slot->ops;
 	unsigned long lattention;
 	u8 attention;
 	int retval = 0;
@@ -147,13 +148,13 @@ static ssize_t attention_write_file(struct pci_slot *pci_slot, const char *buf,
 	attention = (u8)(lattention & 0xff);
 	dbg(" - attention = %d\n", attention);
 
-	if (!try_module_get(ops->owner)) {
+	if (!try_module_get(slot->owner)) {
 		retval = -ENODEV;
 		goto exit;
 	}
 	if (ops->set_attention_status)
-		retval = ops->set_attention_status(pci_slot->hotplug, attention);
-	module_put(ops->owner);
+		retval = ops->set_attention_status(slot, attention);
+	module_put(slot->owner);
 
 exit:
 	if (retval)
@@ -213,13 +214,13 @@ static ssize_t test_write_file(struct pci_slot *pci_slot, const char *buf,
 	test = (u32)(ltest & 0xffffffff);
 	dbg("test = %d\n", test);
 
-	if (!try_module_get(slot->ops->owner)) {
+	if (!try_module_get(slot->owner)) {
 		retval = -ENODEV;
 		goto exit;
 	}
 	if (slot->ops->hardware_test)
 		retval = slot->ops->hardware_test(slot, test);
-	module_put(slot->ops->owner);
+	module_put(slot->owner);
 
 exit:
 	if (retval)
@@ -447,8 +448,8 @@ int __pci_hp_initialize(struct hotplug_slot *slot, struct pci_bus *bus,
 	if ((slot->info == NULL) || (slot->ops == NULL))
 		return -EINVAL;
 
-	slot->ops->owner = owner;
-	slot->ops->mod_name = mod_name;
+	slot->owner = owner;
+	slot->mod_name = mod_name;
 
 	/*
 	 * No problems if we call this interface from both ACPI_PCI_SLOT
diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c
index 3276a5e4c430..12b92a0ff688 100644
--- a/drivers/pci/hotplug/pnv_php.c
+++ b/drivers/pci/hotplug/pnv_php.c
@@ -530,7 +530,7 @@ static int pnv_php_disable_slot(struct hotplug_slot *slot)
 	return ret;
 }
 
-static struct hotplug_slot_ops php_slot_ops = {
+static const struct hotplug_slot_ops php_slot_ops = {
 	.get_power_status	= pnv_php_get_power_state,
 	.get_adapter_status	= pnv_php_get_adapter_state,
 	.set_attention_status	= pnv_php_set_attention_state,
diff --git a/drivers/pci/hotplug/rpaphp.h b/drivers/pci/hotplug/rpaphp.h
index c8311724bd76..f83347819f7b 100644
--- a/drivers/pci/hotplug/rpaphp.h
+++ b/drivers/pci/hotplug/rpaphp.h
@@ -70,7 +70,7 @@ struct slot {
 	struct hotplug_slot *hotplug_slot;
 };
 
-extern struct hotplug_slot_ops rpaphp_hotplug_slot_ops;
+extern const struct hotplug_slot_ops rpaphp_hotplug_slot_ops;
 extern struct list_head rpaphp_slot_head;
 
 /* function prototypes */
diff --git a/drivers/pci/hotplug/rpaphp_core.c b/drivers/pci/hotplug/rpaphp_core.c
index 857c358b727b..8620a3f8c987 100644
--- a/drivers/pci/hotplug/rpaphp_core.c
+++ b/drivers/pci/hotplug/rpaphp_core.c
@@ -477,7 +477,7 @@ static int disable_slot(struct hotplug_slot *hotplug_slot)
 	return 0;
 }
 
-struct hotplug_slot_ops rpaphp_hotplug_slot_ops = {
+const struct hotplug_slot_ops rpaphp_hotplug_slot_ops = {
 	.enable_slot = enable_slot,
 	.disable_slot = disable_slot,
 	.set_attention_status = set_attention_status,
diff --git a/drivers/pci/hotplug/s390_pci_hpc.c b/drivers/pci/hotplug/s390_pci_hpc.c
index 93b5341d282c..5bd45fd4a92a 100644
--- a/drivers/pci/hotplug/s390_pci_hpc.c
+++ b/drivers/pci/hotplug/s390_pci_hpc.c
@@ -130,7 +130,7 @@ static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
 	return 0;
 }
 
-static struct hotplug_slot_ops s390_hotplug_slot_ops = {
+static const struct hotplug_slot_ops s390_hotplug_slot_ops = {
 	.enable_slot =		enable_slot,
 	.disable_slot =		disable_slot,
 	.get_power_status =	get_power_status,
diff --git a/drivers/pci/hotplug/sgi_hotplug.c b/drivers/pci/hotplug/sgi_hotplug.c
index babd23409f61..af4c28c574dd 100644
--- a/drivers/pci/hotplug/sgi_hotplug.c
+++ b/drivers/pci/hotplug/sgi_hotplug.c
@@ -80,7 +80,7 @@ static int enable_slot(struct hotplug_slot *slot);
 static int disable_slot(struct hotplug_slot *slot);
 static inline int get_power_status(struct hotplug_slot *slot, u8 *value);
 
-static struct hotplug_slot_ops sn_hotplug_slot_ops = {
+static const struct hotplug_slot_ops sn_hotplug_slot_ops = {
 	.enable_slot            = enable_slot,
 	.disable_slot           = disable_slot,
 	.get_power_status       = get_power_status,
diff --git a/drivers/pci/hotplug/shpchp_core.c b/drivers/pci/hotplug/shpchp_core.c
index 97cee23f3d51..26cbea04237c 100644
--- a/drivers/pci/hotplug/shpchp_core.c
+++ b/drivers/pci/hotplug/shpchp_core.c
@@ -51,7 +51,7 @@ static int get_attention_status(struct hotplug_slot *slot, u8 *value);
 static int get_latch_status(struct hotplug_slot *slot, u8 *value);
 static int get_adapter_status(struct hotplug_slot *slot, u8 *value);
 
-static struct hotplug_slot_ops shpchp_hotplug_slot_ops = {
+static const struct hotplug_slot_ops shpchp_hotplug_slot_ops = {
 	.set_attention_status =	set_attention_status,
 	.enable_slot =		enable_slot,
 	.disable_slot =		disable_slot,