[PATCH 5/5] crypto: caam - disable CAAM's bind/unbind attributes
From: Andrey Smirnov
Date: Tue Nov 05 2019 - 10:14:11 EST
Exposing bind/unbind attributes for CAAM device allows user to
circumvent module use counter and remove underlying device even while
it is still in use by crypto API. The problem can be easily reproduce
using the following sinppiet:
$ openssl speed -evp aes-128-cbc -engine afalg &
$ echo 30900000.crypto > /sys/bus/platform/drivers/caam/unbind
[ 164.797687] ------------[ cut here ]------------
[ 164.802320] kernel BUG at crypto/algapi.c:412!
[ 164.806771] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[ 164.812260] Modules linked in: crct10dif_ce caam caamhash_desc caamalg_desc error btusb btbcm btintel
[ 164.821506] CPU: 1 PID: 2170 Comm: sh Not tainted 5.4.0-rc1 #30
[ 164.827428] Hardware name: ZII i.MX8MQ Ultra Zest Board (DT)
[ 164.833091] pstate: 20000005 (nzCv daif -PAN -UAO)
[ 164.837897] pc : crypto_unregister_alg+0xe4/0xf0
[ 164.842520] lr : crypto_unregister_alg+0x8c/0xf0
[ 164.847138] sp : ffff8000130f3b20
[ 164.850454] x29: ffff8000130f3b20 x28: ffff0000f1131a80
[ 164.855771] x27: 0000000000000000 x26: 0000000000000000
[ 164.861087] x25: ffff0000fa147ea0 x24: 0000000000000020
[ 164.866404] x23: ffff8000130f3c58 x22: ffff8000130f3b58
[ 164.871721] x21: ffff800012b787c8 x20: ffff800012be7ef0
[ 164.877037] x19: ffff800008ad7300 x18: 000000000000002b
[ 164.882353] x17: 0000000000000000 x16: 0000000000000000
[ 164.887670] x15: ffff800012b8f4d0 x14: 55980d468eb0c075
[ 164.892987] x13: 4375a0958c16498f x12: 27cb4484db878b3d
[ 164.898304] x11: c3bdc615f6902956 x10: e030849201295489
[ 164.903620] x9 : 00a97e1a31855afa x8 : 00000000000014a5
[ 164.908937] x7 : ffff800008ad7310 x6 : ffff8000130f3a60
[ 164.914253] x5 : ffff8000130f3af8 x4 : ffff800008ad7310
[ 164.919570] x3 : 0000000000000000 x2 : 0000000000000000
[ 164.924886] x1 : ffffffffffffffff x0 : 0000000000000002
[ 164.930202] Call trace:
[ 164.932656] crypto_unregister_alg+0xe4/0xf0
[ 164.936932] crypto_unregister_skcipher+0x20/0x30
[ 164.941662] caam_algapi_exit+0x84/0xa0 [caam]
[ 164.946124] caam_jr_remove+0x54/0xd0 [caam]
[ 164.950401] devm_action_release+0x20/0x30
[ 164.954501] release_nodes+0x1c8/0x240
[ 164.958255] devres_release_all+0x3c/0x60
[ 164.962272] device_release_driver_internal+0x10c/0x1c0
[ 164.967501] device_driver_detach+0x28/0x40
[ 164.971689] unbind_store+0x94/0x100
[ 164.975269] drv_attr_store+0x40/0x60
[ 164.978938] sysfs_kf_write+0x5c/0x70
[ 164.982605] kernfs_fop_write+0xf4/0x1f0
[ 164.986534] __vfs_write+0x48/0x90
[ 164.989941] vfs_write+0xb8/0x1d0
[ 164.993261] ksys_write+0x74/0x100
[ 164.996668] __arm64_sys_write+0x24/0x30
[ 165.000598] el0_svc_handler+0x94/0x100
[ 165.004439] el0_svc+0x8/0xc
[ 165.007329] Code: aa1403e0 97f2d52e 12800020 17fffff5 (d4210000)
[ 165.013428] ---[ end trace 11587fd1ef597dd6 ]---
[ 165.018138] note: sh[2170] exited with preempt_count 1
[ 165.024146] ------------[ cut here ]------------
[ 165.028786] WARNING: CPU: 1 PID: 0 at kernel/rcu/tree.c:569 rcu_idle_enter+0x7c/0x90
[ 165.048977] Hardware name: ZII i.MX8MQ Ultra Zest Board (DT)
[ 165.054640] pstate: 200003c5 (nzCv DAIF -PAN -UAO)
[ 165.059435] pc : rcu_idle_enter+0x7c/0x90
[ 165.063450] lr : do_idle+0x218/0x2b0
[ 165.067027] sp : ffff800012e1bf20
[ 165.070343] x29: ffff800012e1bf20 x28: 0000000000000000
[ 165.075663] x27: 0000000000000000 x26: 0000000000000000
[ 165.080983] x25: 0000000000000000 x24: ffff800012b78884
[ 165.089045] x21: ffff800012b78860 x20: 0000000000000002
[ 165.094362] x19: ffff800012b787e8 x18: 0000000000000010
[ 165.099678] x17: 0000000000000000 x16: 0000000000000001
[ 165.104995] x15: ffff0000ff789170 x14: 0000000000000001
[ 165.110311] x13: ffff0000ff7a8170 x12: ffff0000fa996cd4
[ 165.115628] x11: ffff0000fa996cd4 x10: 0000000000000970
[ 165.120945] x9 : ffff800012e1bea0 x8 : ffff0000fa9aa450
[ 165.126261] x7 : 0000000000000001 x6 : ffff800012e1bee0
[ 165.131577] x5 : 0000000000000001 x4 : ffff800012cc61a8
[ 165.136894] x3 : 4000000000000002 x2 : 4000000000000000
[ 165.142210] x1 : ffff800012b6edc0 x0 : ffff0000ff789dc0
[ 165.147526] Call trace:
[ 165.149978] rcu_idle_enter+0x7c/0x90
[ 165.153644] do_idle+0x218/0x2b0
[ 165.156876] cpu_startup_entry+0x2c/0x50
[ 165.160806] secondary_start_kernel+0x164/0x180
[ 165.165339] ---[ end trace 11587fd1ef597dd7 ]---
Remove bind/unbind attributes of CAAM device, so that the only way to
remove it during runtime would be to remove underlying kernel module.
Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
Cc: Chris Healy <cphealy@xxxxxxxxx>
Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
Cc: Horia GeantÄ <horia.geanta@xxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Iuliana Prodan <iuliana.prodan@xxxxxxx>
Cc: linux-imx@xxxxxxx
Cc: linux-crypto@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
drivers/crypto/caam/ctrl.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/crypto/caam/ctrl.c b/drivers/crypto/caam/ctrl.c
index 0fb39bcf638a..e0c16cd2ce1a 100644
--- a/drivers/crypto/caam/ctrl.c
+++ b/drivers/crypto/caam/ctrl.c
@@ -920,6 +920,7 @@ static struct platform_driver caam_driver = {
.driver = {
.name = "caam",
.of_match_table = caam_match,
+ .suppress_bind_attrs = true,
},
.probe = caam_probe,
};
--
2.21.0