Enable support to register kernel memory reference with TEE. This change will allow TEE bus drivers to register memory references.

Signed-off-by: Sumit Garg sumit.garg@linaro.org --- drivers/tee/tee_shm.c | 16 ++++++++++++++-- include/linux/tee_drv.h | 1 + 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c index 2da026f..5c69b89 100644 --- a/drivers/tee/tee_shm.c +++ b/drivers/tee/tee_shm.c @@ -9,6 +9,7 @@ #include <linux/sched.h> #include <linux/slab.h> #include <linux/tee_drv.h> +#include <linux/uio.h> #include "tee_private.h"

static void tee_shm_release(struct tee_shm *shm) @@ -224,13 +225,14 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr, { struct tee_device *teedev = ctx->teedev; const u32 req_flags = TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED; + const u32 req_ker_flags = TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED; struct tee_shm *shm; void *ret; int rc; int num_pages; unsigned long start;

- if (flags != req_flags) + if (flags != req_flags && flags != req_ker_flags) return ERR_PTR(-ENOTSUPP);

if (!tee_device_get(teedev)) @@ -264,7 +266,17 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr, goto err; }

- rc = get_user_pages_fast(start, num_pages, FOLL_WRITE, shm->pages); + if (flags & TEE_SHM_USER_MAPPED) { + rc = get_user_pages_fast(start, num_pages, FOLL_WRITE, + shm->pages); + } else { + const struct kvec kiov = { + .iov_base = (void *)start, + .iov_len = PAGE_SIZE + }; + + rc = get_kernel_pages(&kiov, num_pages, 0, shm->pages); + } if (rc > 0) shm->num_pages = rc; if (rc != num_pages) { diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h index 7a03f68..dedf8fa 100644 --- a/include/linux/tee_drv.h +++ b/include/linux/tee_drv.h @@ -26,6 +26,7 @@ #define TEE_SHM_REGISTER BIT(3) /* Memory registered in secure world */ #define TEE_SHM_USER_MAPPED BIT(4) /* Memory mapped in user space */ #define TEE_SHM_POOL BIT(5) /* Memory allocated from pool */ +#define TEE_SHM_KERNEL_MAPPED BIT(6) /* Memory mapped in kernel space */

struct device; struct tee_device;

Add support for TEE based trusted keys where TEE provides the functionality to seal and unseal trusted keys using hardware unique key.

Refer to Documentation/tee.txt for detailed information about TEE.

Approach taken in this patch acts as an alternative to a TPM device in case platform doesn't possess one.

Signed-off-by: Sumit Garg sumit.garg@linaro.org --- include/keys/tee_trusted.h | 84 ++++++++ include/keys/trusted-type.h | 1 + security/keys/Kconfig | 3 + security/keys/Makefile | 3 + security/keys/tee_trusted.c | 506 ++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 597 insertions(+) create mode 100644 include/keys/tee_trusted.h create mode 100644 security/keys/tee_trusted.c

diff --git a/include/keys/tee_trusted.h b/include/keys/tee_trusted.h new file mode 100644 index 0000000..e5c0042 --- /dev/null +++ b/include/keys/tee_trusted.h @@ -0,0 +1,84 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2019 Linaro Ltd. + * + * Author: + * Sumit Garg sumit.garg@linaro.org + */ + +#ifndef __TEE_TRUSTED_KEY_H +#define __TEE_TRUSTED_KEY_H + +#include <linux/tee_drv.h> + +#define DRIVER_NAME "tee-trusted-key" + +/* + * Get random data for symmetric key + * + * [out] memref[0] Random data + * + * Result: + * TEE_SUCCESS - Invoke command success + * TEE_ERROR_BAD_PARAMETERS - Incorrect input param + */ +#define TA_CMD_GET_RANDOM 0x0 + +/* + * Seal trusted key using hardware unique key + * + * [in] memref[0] Plain key + * [out] memref[1] Sealed key datablob + * + * Result: + * TEE_SUCCESS - Invoke command success + * TEE_ERROR_BAD_PARAMETERS - Incorrect input param + */ +#define TA_CMD_SEAL 0x1 + +/* + * Unseal trusted key using hardware unique key + * + * [in] memref[0] Sealed key datablob + * [out] memref[1] Plain key + * + * Result: + * TEE_SUCCESS - Invoke command success + * TEE_ERROR_BAD_PARAMETERS - Incorrect input param + */ +#define TA_CMD_UNSEAL 0x2 + +/** + * struct trusted_key_private - TEE Trusted key private data + * @dev: TEE based Trusted key device. + * @ctx: TEE context handler. + * @session_id: Trusted key TA session identifier. + * @shm_pool: Memory pool shared with TEE device. + */ +struct trusted_key_private { + struct device *dev; + struct tee_context *ctx; + u32 session_id; + u32 data_rate; + struct tee_shm *shm_pool; +}; + +#define TEE_KEY_DEBUG 0 + +#if TEE_KEY_DEBUG +static inline void dump_tee_payload(struct trusted_key_payload *p) +{ + pr_info("trusted_key: key_len %d\n", p->key_len); + print_hex_dump(KERN_INFO, "key ", DUMP_PREFIX_NONE, + 16, 1, p->key, p->key_len, 0); + pr_info("trusted_key: bloblen %d\n", p->blob_len); + print_hex_dump(KERN_INFO, "blob ", DUMP_PREFIX_NONE, + 16, 1, p->blob, p->blob_len, 0); +} +#else +static inline void dump_tee_payload(struct trusted_key_payload *p) +{ +} +#endif + +#endif diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h index a94c03a..363ec83 100644 --- a/include/keys/trusted-type.h +++ b/include/keys/trusted-type.h @@ -41,5 +41,6 @@ struct trusted_key_options { };

extern struct key_type key_type_trusted; +extern struct key_type key_type_tee_trusted;

#endif /* _KEYS_TRUSTED_TYPE_H */ diff --git a/security/keys/Kconfig b/security/keys/Kconfig index ee502e4..b206a20 100644 --- a/security/keys/Kconfig +++ b/security/keys/Kconfig @@ -70,6 +70,9 @@ config TRUSTED_KEYS if the boot PCRs and other criteria match. Userspace will only ever see encrypted blobs.

+ It also provides support for alternative TEE based Trusted keys + generation and sealing in case TPM isn't present. + If you are unsure as to whether this is required, answer N.

config ENCRYPTED_KEYS diff --git a/security/keys/Makefile b/security/keys/Makefile index 9cef540..07ad3e2 100644 --- a/security/keys/Makefile +++ b/security/keys/Makefile @@ -30,3 +30,6 @@ obj-$(CONFIG_ASYMMETRIC_KEY_TYPE) += keyctl_pkey.o obj-$(CONFIG_BIG_KEYS) += big_key.o obj-$(CONFIG_TRUSTED_KEYS) += trusted.o obj-$(CONFIG_ENCRYPTED_KEYS) += encrypted-keys/ +ifdef CONFIG_TEE +obj-$(CONFIG_TRUSTED_KEYS) += tee_trusted.o +endif diff --git a/security/keys/tee_trusted.c b/security/keys/tee_trusted.c new file mode 100644 index 0000000..081e45e --- /dev/null +++ b/security/keys/tee_trusted.c @@ -0,0 +1,506 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 Linaro Ltd. + * + * Author: + * Sumit Garg sumit.garg@linaro.org + */ + +#include <linux/err.h> +#include <linux/key-type.h> +#include <linux/module.h> +#include <linux/parser.h> +#include <linux/rcupdate.h> +#include <linux/slab.h> +#include <linux/string.h> +#include <linux/tpm.h> +#include <linux/uaccess.h> +#include <linux/uuid.h> + +#include <keys/trusted-type.h> +#include <keys/user-type.h> +#include <keys/tee_trusted.h> + +static struct trusted_key_private pvt_data; + +/* + * Have the TEE seal(encrypt) the symmetric key + */ +static int tee_key_seal(struct trusted_key_payload *p) +{ + int ret = 0; + struct tee_ioctl_invoke_arg inv_arg; + struct tee_param param[4]; + struct tee_shm *reg_shm_in = NULL, *reg_shm_out = NULL; + + memset(&inv_arg, 0, sizeof(inv_arg)); + memset(&param, 0, sizeof(param)); + + reg_shm_in = tee_shm_register(pvt_data.ctx, (unsigned long)p->key, + p->key_len, TEE_SHM_DMA_BUF | + TEE_SHM_KERNEL_MAPPED); + if (IS_ERR(reg_shm_in)) { + dev_err(pvt_data.dev, "key shm register failed\n"); + return PTR_ERR(reg_shm_in); + } + + reg_shm_out = tee_shm_register(pvt_data.ctx, (unsigned long)p->blob, + sizeof(p->blob), TEE_SHM_DMA_BUF | + TEE_SHM_KERNEL_MAPPED); + if (IS_ERR(reg_shm_out)) { + dev_err(pvt_data.dev, "blob shm register failed\n"); + ret = PTR_ERR(reg_shm_out); + goto out; + } + + inv_arg.func = TA_CMD_SEAL; + inv_arg.session = pvt_data.session_id; + inv_arg.num_params = 4; + + param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT; + param[0].u.memref.shm = reg_shm_in; + param[0].u.memref.size = p->key_len; + param[0].u.memref.shm_offs = 0; + param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT; + param[1].u.memref.shm = reg_shm_out; + param[1].u.memref.size = sizeof(p->blob); + param[1].u.memref.shm_offs = 0; + + ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param); + if ((ret < 0) || (inv_arg.ret != 0)) { + dev_err(pvt_data.dev, "TA_CMD_SEAL invoke err: %x\n", + inv_arg.ret); + ret = -EFAULT; + } else { + p->blob_len = param[1].u.memref.size; + } + +out: + if (reg_shm_out) + tee_shm_free(reg_shm_out); + if (reg_shm_in) + tee_shm_free(reg_shm_in); + + return ret; +} + +/* + * Have the TEE unseal(decrypt) the symmetric key + */ +static int tee_key_unseal(struct trusted_key_payload *p) +{ + int ret = 0; + struct tee_ioctl_invoke_arg inv_arg; + struct tee_param param[4]; + struct tee_shm *reg_shm_in = NULL, *reg_shm_out = NULL; + + memset(&inv_arg, 0, sizeof(inv_arg)); + memset(&param, 0, sizeof(param)); + + reg_shm_in = tee_shm_register(pvt_data.ctx, (unsigned long)p->blob, + p->blob_len, TEE_SHM_DMA_BUF | + TEE_SHM_KERNEL_MAPPED); + if (IS_ERR(reg_shm_in)) { + dev_err(pvt_data.dev, "blob shm register failed\n"); + return PTR_ERR(reg_shm_in); + } + + reg_shm_out = tee_shm_register(pvt_data.ctx, (unsigned long)p->key, + sizeof(p->key), TEE_SHM_DMA_BUF | + TEE_SHM_KERNEL_MAPPED); + if (IS_ERR(reg_shm_out)) { + dev_err(pvt_data.dev, "key shm register failed\n"); + ret = PTR_ERR(reg_shm_out); + goto out; + } + + inv_arg.func = TA_CMD_UNSEAL; + inv_arg.session = pvt_data.session_id; + inv_arg.num_params = 4; + + param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT; + param[0].u.memref.shm = reg_shm_in; + param[0].u.memref.size = p->blob_len; + param[0].u.memref.shm_offs = 0; + param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT; + param[1].u.memref.shm = reg_shm_out; + param[1].u.memref.size = sizeof(p->key); + param[1].u.memref.shm_offs = 0; + + ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param); + if ((ret < 0) || (inv_arg.ret != 0)) { + dev_err(pvt_data.dev, "TA_CMD_UNSEAL invoke err: %x\n", + inv_arg.ret); + ret = -EFAULT; + } else { + p->key_len = param[1].u.memref.size; + } + +out: + if (reg_shm_out) + tee_shm_free(reg_shm_out); + if (reg_shm_in) + tee_shm_free(reg_shm_in); + + return ret; +} + +/* + * Have the TEE generate random symmetric key + */ +static int tee_get_random(unsigned char *key, unsigned int key_len) +{ + int ret = 0; + struct tee_ioctl_invoke_arg inv_arg; + struct tee_param param[4]; + struct tee_shm *reg_shm = NULL; + + memset(&inv_arg, 0, sizeof(inv_arg)); + memset(&param, 0, sizeof(param)); + + reg_shm = tee_shm_register(pvt_data.ctx, (unsigned long)key, key_len, + TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED); + if (IS_ERR(reg_shm)) { + dev_err(pvt_data.dev, "random key shm register failed\n"); + return PTR_ERR(reg_shm); + } + + inv_arg.func = TA_CMD_GET_RANDOM; + inv_arg.session = pvt_data.session_id; + inv_arg.num_params = 4; + + param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT; + param[0].u.memref.shm = reg_shm; + param[0].u.memref.size = key_len; + param[0].u.memref.shm_offs = 0; + + ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param); + if ((ret < 0) || (inv_arg.ret != 0)) { + dev_err(pvt_data.dev, "TA_CMD_GET_RANDOM invoke err: %x\n", + inv_arg.ret); + ret = -EFAULT; + } else { + ret = param[0].u.memref.size; + } + + tee_shm_free(reg_shm); + + return ret; +} + +enum { + Opt_err, + Opt_new, Opt_load +}; + +static const match_table_t key_tokens = { + {Opt_new, "new"}, + {Opt_load, "load"}, + {Opt_err, NULL} +}; + +/* + * datablob_parse - parse the keyctl data and fill in the + * payload structure + * + * On success returns 0, otherwise -EINVAL. + */ +static int datablob_parse(char *datablob, struct trusted_key_payload *p) +{ + substring_t args[MAX_OPT_ARGS]; + long keylen; + int ret = -EINVAL; + int key_cmd; + char *c; + + /* main command */ + c = strsep(&datablob, " \t"); + if (!c) + return -EINVAL; + + key_cmd = match_token(c, key_tokens, args); + switch (key_cmd) { + case Opt_new: + /* first argument is key size */ + c = strsep(&datablob, " \t"); + if (!c) + return -EINVAL; + ret = kstrtol(c, 10, &keylen); + if (ret < 0 || keylen < MIN_KEY_SIZE || keylen > MAX_KEY_SIZE) + return -EINVAL; + p->key_len = keylen; + ret = Opt_new; + break; + case Opt_load: + /* first argument is sealed blob */ + c = strsep(&datablob, " \t"); + if (!c) + return -EINVAL; + p->blob_len = strlen(c) / 2; + if (p->blob_len > MAX_BLOB_SIZE) + return -EINVAL; + ret = hex2bin(p->blob, c, p->blob_len); + if (ret < 0) + return -EINVAL; + ret = Opt_load; + break; + case Opt_err: + return -EINVAL; + } + + return ret; +} + +static struct trusted_key_payload *trusted_payload_alloc(struct key *key) +{ + struct trusted_key_payload *p = NULL; + int ret; + + ret = key_payload_reserve(key, sizeof(*p)); + if (ret < 0) + return p; + + p = kzalloc(sizeof(*p), GFP_KERNEL); + + return p; +} + +/* + * trusted_instantiate - create a new trusted key + * + * Unseal an existing trusted blob or, for a new key, get a + * random key, then seal and create a trusted key-type key, + * adding it to the specified keyring. + * + * On success, return 0. Otherwise return errno. + */ +static int trusted_instantiate(struct key *key, + struct key_preparsed_payload *prep) +{ + struct trusted_key_payload *payload = NULL; + size_t datalen = prep->datalen; + char *datablob; + int ret = 0; + int key_cmd; + size_t key_len; + + if (datalen <= 0 || datalen > 32767 || !prep->data) + return -EINVAL; + + datablob = kmalloc(datalen + 1, GFP_KERNEL); + if (!datablob) + return -ENOMEM; + memcpy(datablob, prep->data, datalen); + datablob[datalen] = '\0'; + + payload = trusted_payload_alloc(key); + if (!payload) { + ret = -ENOMEM; + goto out; + } + + key_cmd = datablob_parse(datablob, payload); + if (key_cmd < 0) { + ret = key_cmd; + goto out; + } + + dump_tee_payload(payload); + + switch (key_cmd) { + case Opt_load: + ret = tee_key_unseal(payload); + dump_tee_payload(payload); + if (ret < 0) + dev_err(pvt_data.dev, "key_unseal failed (%d)\n", ret); + break; + case Opt_new: + key_len = payload->key_len; + ret = tee_get_random(payload->key, key_len); + if (ret != key_len) { + dev_err(pvt_data.dev, "key_create failed (%d)\n", ret); + goto out; + } + + ret = tee_key_seal(payload); + if (ret < 0) + dev_err(pvt_data.dev, "key_seal failed (%d)\n", ret); + dump_tee_payload(payload); + break; + default: + ret = -EINVAL; + goto out; + } +out: + kzfree(datablob); + if (!ret) + rcu_assign_keypointer(key, payload); + else + kzfree(payload); + return ret; +} + +static int trusted_update(struct key *key, struct key_preparsed_payload *prep) +{ + dev_info(pvt_data.dev, "trusted key update method not supported\n"); + + return -EINVAL; +} + +/* + * trusted_read - copy the sealed blob data to userspace in hex. + * On success, return to userspace the trusted key datablob size. + */ +static long trusted_read(const struct key *key, char __user *buffer, + size_t buflen) +{ + const struct trusted_key_payload *p; + char *ascii_buf; + char *bufp; + int i; + + p = dereference_key_locked(key); + if (!p) + return -EINVAL; + + if (buffer && buflen >= 2 * p->blob_len) { + ascii_buf = kmalloc_array(2, p->blob_len, GFP_KERNEL); + if (!ascii_buf) + return -ENOMEM; + + bufp = ascii_buf; + for (i = 0; i < p->blob_len; i++) + bufp = hex_byte_pack(bufp, p->blob[i]); + if (copy_to_user(buffer, ascii_buf, 2 * p->blob_len) != 0) { + kzfree(ascii_buf); + return -EFAULT; + } + kzfree(ascii_buf); + } + return 2 * p->blob_len; +} + +/* + * trusted_destroy - clear and free the key's payload + */ +static void trusted_destroy(struct key *key) +{ + kzfree(key->payload.data[0]); +} + +struct key_type key_type_tee_trusted = { + .name = "trusted", + .instantiate = trusted_instantiate, + .update = trusted_update, + .destroy = trusted_destroy, + .describe = user_describe, + .read = trusted_read, +}; +EXPORT_SYMBOL_GPL(key_type_tee_trusted); + +static int optee_ctx_match(struct tee_ioctl_version_data *ver, const void *data) +{ + if (ver->impl_id == TEE_IMPL_ID_OPTEE) + return 1; + else + return 0; +} + +static int trusted_key_probe(struct device *dev) +{ + struct tee_client_device *rng_device = to_tee_client_device(dev); + int ret = 0, err = -ENODEV; + struct tee_ioctl_open_session_arg sess_arg; + + memset(&sess_arg, 0, sizeof(sess_arg)); + + /* Open context with TEE driver */ + pvt_data.ctx = tee_client_open_context(NULL, optee_ctx_match, NULL, + NULL); + if (IS_ERR(pvt_data.ctx)) + return -ENODEV; + + /* Open session with hwrng Trusted App */ + memcpy(sess_arg.uuid, rng_device->id.uuid.b, TEE_IOCTL_UUID_LEN); + sess_arg.clnt_login = TEE_IOCTL_LOGIN_REE_KERNEL; + sess_arg.num_params = 0; + + ret = tee_client_open_session(pvt_data.ctx, &sess_arg, NULL); + if ((ret < 0) || (sess_arg.ret != 0)) { + dev_err(dev, "tee_client_open_session failed, err: %x\n", + sess_arg.ret); + err = -EINVAL; + goto out_ctx; + } + pvt_data.session_id = sess_arg.session; + + ret = register_key_type(&key_type_tee_trusted); + if (ret < 0) + goto out_sess; + + pvt_data.dev = dev; + + return 0; + +out_sess: + tee_client_close_session(pvt_data.ctx, pvt_data.session_id); +out_ctx: + tee_client_close_context(pvt_data.ctx); + + return err; +} + +static int trusted_key_remove(struct device *dev) +{ + unregister_key_type(&key_type_tee_trusted); + tee_client_close_session(pvt_data.ctx, pvt_data.session_id); + tee_client_close_context(pvt_data.ctx); + + return 0; +} + +static const struct tee_client_device_id trusted_key_id_table[] = { + {UUID_INIT(0xf04a0fe7, 0x1f5d, 0x4b9b, + 0xab, 0xf7, 0x61, 0x9b, 0x85, 0xb4, 0xce, 0x8c)}, + {} +}; + +MODULE_DEVICE_TABLE(tee, trusted_key_id_table); + +static struct tee_client_driver trusted_key_driver = { + .id_table = trusted_key_id_table, + .driver = { + .name = DRIVER_NAME, + .bus = &tee_bus_type, + .probe = trusted_key_probe, + .remove = trusted_key_remove, + }, +}; + +static int __init init_tee_trusted(void) +{ + struct tpm_chip *chip; + + /* + * Check for TPM availability as that is default source for trusted + * keys. If not present, then register driver for TEE based device + * providing support for trusted keys. + */ + chip = tpm_default_chip(); + if (chip) + return 0; + + return driver_register(&trusted_key_driver.driver); +} + +static void __exit cleanup_tee_trusted(void) +{ + driver_unregister(&trusted_key_driver.driver); +} + +late_initcall(init_tee_trusted); +module_exit(cleanup_tee_trusted); + +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Sumit Garg sumit.garg@linaro.org"); +MODULE_DESCRIPTION("TEE based trusted keys");

Provide documentation for usage of TEE based Trusted Keys via existing user-space "keyctl" utility. Also, document various use-cases.

Signed-off-by: Sumit Garg sumit.garg@linaro.org --- Documentation/security/keys/tee-trusted.rst | 93 +++++++++++++++++++++++++++++ 1 file changed, 93 insertions(+) create mode 100644 Documentation/security/keys/tee-trusted.rst

diff --git a/Documentation/security/keys/tee-trusted.rst b/Documentation/security/keys/tee-trusted.rst new file mode 100644 index 0000000..ef03745 --- /dev/null +++ b/Documentation/security/keys/tee-trusted.rst @@ -0,0 +1,93 @@ +====================== +TEE based Trusted Keys +====================== + +TEE based Trusted Keys provides an alternative approach for providing Trusted +Keys in case TPM chip isn't present. + +Trusted Keys use a TEE service/device both to generate and to seal the keys. +Keys are sealed under a hardware unique key in the TEE, and only unsealed by +the TEE. + +For more information about TEE, refer to ``Documentation/tee.txt``. + +Usage:: + + keyctl add trusted name "new keylen" ring + keyctl add trusted name "load hex_blob" ring + keyctl print keyid + +"keyctl print" returns an ascii hex copy of the sealed key, which is in format +specific to TEE device implementation. The key length for new keys are always +in bytes. Trusted Keys can be 32 - 128 bytes (256 - 1024 bits). + +Examples of trusted key and its usage as 'master' key for encrypted key usage: + +More details about encrypted keys can be found here: +``Documentation/security/keys/trusted-encrypted.rst`` + +Create and save a trusted key named "kmk" of length 32 bytes:: + + $ keyctl add trusted kmk "new 32" @u + 754414669 + + $ keyctl show + Session Keyring + 827385718 --alswrv 0 65534 keyring: _uid_ses.0 + 274124851 --alswrv 0 65534 _ keyring: _uid.0 + 754414669 --als-rv 0 0 _ trusted: kmk + + $ keyctl print 754414669 + 15676790697861b422175596ae001c2f505cea2c6f3ebbc5fb08eeb1f343a07e + + $ keyctl pipe 754414669 > kmk.blob + +Load a trusted key from the saved blob:: + + $ keyctl add trusted kmk "load `cat kmk.blob`" @u + 491638700 + + $ keyctl print 491638700 + 15676790697861b422175596ae001c2f505cea2c6f3ebbc5fb08eeb1f343a07e + +The initial consumer of trusted keys is EVM, which at boot time needs a high +quality symmetric key for HMAC protection of file metadata. The use of a +TEE based trusted key provides security that the EVM key has not been +compromised by a user level problem and tied to particular hardware. + +Create and save an encrypted key "evm" using the above trusted key "kmk": + +option 1: omitting 'format':: + + $ keyctl add encrypted evm "new trusted:kmk 32" @u + 608915065 + +option 2: explicitly defining 'format' as 'default':: + + $ keyctl add encrypted evm "new default trusted:kmk 32" @u + 608915065 + + $ keyctl print 608915065 + default trusted:kmk 32 f380ac588a925f488d5be007cf23e4c900b8b652ab62241c8 + ed54906189b6659d139d619d4b51752a2645537b11fd44673f13154a65b3f595d5fb2131 + 2fe45529ea0407c644ea4026f2a1a75661f2c9b66 + + $ keyctl pipe 608915065 > evm.blob + +Load an encrypted key "evm" from saved blob:: + + $ keyctl add encrypted evm "load `cat evm.blob`" @u + 831684262 + + $ keyctl print 831684262 + default trusted:kmk 32 f380ac588a925f488d5be007cf23e4c900b8b652ab62241c8 + ed54906189b6659d139d619d4b51752a2645537b11fd44673f13154a65b3f595d5fb2131 + 2fe45529ea0407c644ea4026f2a1a75661f2c9b66 + +Other uses for trusted and encrypted keys, such as for disk and file encryption +are anticipated. In particular the 'ecryptfs' encrypted keys format can be used +to mount an eCryptfs filesystem. More details about the usage can be found in +the file ``Documentation/security/keys/ecryptfs.rst``. + +Another format 'enc32' can be used to support encrypted keys with payload size +of 32 bytes.

Hi Sumit,

On Thu, Jun 13, 2019 at 04:00:29PM +0530, Sumit Garg wrote:

There are use-cases where user-space shouldn't be allowed to communicate directly with a TEE device which is dedicated to provide a specific service for a kernel client. So add a private login method for kernel clients and disallow user-space to open-session using this login method.

Signed-off-by: Sumit Garg sumit.garg@linaro.org

drivers/tee/tee_core.c | 6 ++++++ include/uapi/linux/tee.h | 2 ++ 2 files changed, 8 insertions(+)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c index 0f16d9f..4581bd1 100644 --- a/drivers/tee/tee_core.c +++ b/drivers/tee/tee_core.c @@ -334,6 +334,12 @@ static int tee_ioctl_open_session(struct tee_context *ctx, goto out; }

• if (arg.clnt_login == TEE_IOCTL_LOGIN_REE_KERNEL) {

TEE_IOCTL_LOGIN_REE_KERNEL is defined as 0x80000000 which is in the range specified and implementation defined by the GP spec. I wonder if we shouldn't filter the entire implementation defined range instead of just this value.

• pr_err("login method not allowed for user-space client\n");
  

pr_debug(), if it's needed at all.

• rc = -EPERM;
  

• goto out;
  

• }
• rc = ctx->teedev->desc->ops->open_session(ctx, &arg, params); if (rc) goto out;

diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h index 4b9eb06..f33c69c 100644 --- a/include/uapi/linux/tee.h +++ b/include/uapi/linux/tee.h @@ -172,6 +172,8 @@ struct tee_ioctl_buf_data { #define TEE_IOCTL_LOGIN_APPLICATION 4 #define TEE_IOCTL_LOGIN_USER_APPLICATION 5 #define TEE_IOCTL_LOGIN_GROUP_APPLICATION 6 +/* Private login method for REE kernel clients */

It's worth noting that this is filtered by the TEE framework, compared to everything else which is treated opaquely.

+#define TEE_IOCTL_LOGIN_REE_KERNEL 0x80000000 /**

• struct tee_ioctl_param - parameter

-- 2.7.4

Thanks, Jens

Thanks Jens for your comments.

On Mon, 8 Jul 2019 at 21:09, Jens Wiklander jens.wiklander@linaro.org wrote:

Hi Sumit,

On Thu, Jun 13, 2019 at 04:00:29PM +0530, Sumit Garg wrote:

...

There are use-cases where user-space shouldn't be allowed to communicate directly with a TEE device which is dedicated to provide a specific service for a kernel client. So add a private login method for kernel clients and disallow user-space to open-session using this login method.

Signed-off-by: Sumit Garg sumit.garg@linaro.org

drivers/tee/tee_core.c | 6 ++++++ include/uapi/linux/tee.h | 2 ++ 2 files changed, 8 insertions(+)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c index 0f16d9f..4581bd1 100644 --- a/drivers/tee/tee_core.c +++ b/drivers/tee/tee_core.c @@ -334,6 +334,12 @@ static int tee_ioctl_open_session(struct tee_context *ctx, goto out; }

• if (arg.clnt_login == TEE_IOCTL_LOGIN_REE_KERNEL) {
  

TEE_IOCTL_LOGIN_REE_KERNEL is defined as 0x80000000 which is in the range specified and implementation defined by the GP spec. I wonder if we shouldn't filter the entire implementation defined range instead of just this value.

Agree. Will rather check for entire implementation defined range: 0x80000000 - 0xFFFFFFFF.

...

•         pr_err("login method not allowed for user-space client\n");
  

pr_debug(), if it's needed at all.

Ok will use pr_debug() instead.

...

•         rc = -EPERM;
  

•         goto out;
  

• }
  

• rc = ctx->teedev->desc->ops->open_session(ctx, &arg, params);
  if (rc)
          goto out;
  

diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h index 4b9eb06..f33c69c 100644 --- a/include/uapi/linux/tee.h +++ b/include/uapi/linux/tee.h @@ -172,6 +172,8 @@ struct tee_ioctl_buf_data { #define TEE_IOCTL_LOGIN_APPLICATION 4 #define TEE_IOCTL_LOGIN_USER_APPLICATION 5 #define TEE_IOCTL_LOGIN_GROUP_APPLICATION 6 +/* Private login method for REE kernel clients */

It's worth noting that this is filtered by the TEE framework, compared to everything else which is treated opaquely.

IIUC, you are referring to login filter in optee_os. Change to prevent filter for this login method is part of this PR [1].

[1] https://github.com/OP-TEE/optee_os/pull/3082

-Sumit

...

+#define TEE_IOCTL_LOGIN_REE_KERNEL 0x80000000

/**

• struct tee_ioctl_param - parameter

-- 2.7.4

Thanks, Jens

On Tue, Jul 09, 2019 at 11:26:19AM +0530, Sumit Garg wrote:

Thanks Jens for your comments.

On Mon, 8 Jul 2019 at 21:09, Jens Wiklander jens.wiklander@linaro.org wrote:

...

Hi Sumit,

On Thu, Jun 13, 2019 at 04:00:29PM +0530, Sumit Garg wrote:

...

There are use-cases where user-space shouldn't be allowed to communicate directly with a TEE device which is dedicated to provide a specific service for a kernel client. So add a private login method for kernel clients and disallow user-space to open-session using this login method.

Signed-off-by: Sumit Garg sumit.garg@linaro.org

drivers/tee/tee_core.c | 6 ++++++ include/uapi/linux/tee.h | 2 ++ 2 files changed, 8 insertions(+)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c index 0f16d9f..4581bd1 100644 --- a/drivers/tee/tee_core.c +++ b/drivers/tee/tee_core.c @@ -334,6 +334,12 @@ static int tee_ioctl_open_session(struct tee_context *ctx, goto out; }

• if (arg.clnt_login == TEE_IOCTL_LOGIN_REE_KERNEL) {
  

TEE_IOCTL_LOGIN_REE_KERNEL is defined as 0x80000000 which is in the range specified and implementation defined by the GP spec. I wonder if we shouldn't filter the entire implementation defined range instead of just this value.

Agree. Will rather check for entire implementation defined range: 0x80000000 - 0xFFFFFFFF.

...

...

•         pr_err("login method not allowed for user-space client\n");
  

pr_debug(), if it's needed at all.

Ok will use pr_debug() instead.

...

...

•         rc = -EPERM;
  

•         goto out;
  

• }
  

• rc = ctx->teedev->desc->ops->open_session(ctx, &arg, params);
  if (rc)
          goto out;
  

diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h index 4b9eb06..f33c69c 100644 --- a/include/uapi/linux/tee.h +++ b/include/uapi/linux/tee.h @@ -172,6 +172,8 @@ struct tee_ioctl_buf_data { #define TEE_IOCTL_LOGIN_APPLICATION 4 #define TEE_IOCTL_LOGIN_USER_APPLICATION 5 #define TEE_IOCTL_LOGIN_GROUP_APPLICATION 6 +/* Private login method for REE kernel clients */

It's worth noting that this is filtered by the TEE framework, compared to everything else which is treated opaquely.

IIUC, you are referring to login filter in optee_os. Change to prevent filter for this login method is part of this PR [1].

[1] https://github.com/OP-TEE/optee_os/pull/3082

No, I was referring to the changes in tee_ioctl_open_session() above. It's relevant for user space to know since it will be prevented from using that range of login identifiers. This will restrict the user space API, but I think the risk of breakage is minimal as OP-TEE is the only in-tree driver registering in the TEE framework. I'm not aware of any out-of-tree drivers registering.

Thanks, Jens

-Sumit

...

...

+#define TEE_IOCTL_LOGIN_REE_KERNEL 0x80000000

/**

• struct tee_ioctl_param - parameter

-- 2.7.4

Thanks, Jens

Hi Sumit,

On Tue, Jul 9, 2019 at 11:36 AM Sumit Garg sumit.garg@linaro.org wrote:

On Tue, 9 Jul 2019 at 12:33, Jens Wiklander jens.wiklander@linaro.org wrote:

...

On Tue, Jul 09, 2019 at 11:26:19AM +0530, Sumit Garg wrote:

...

Thanks Jens for your comments.

On Mon, 8 Jul 2019 at 21:09, Jens Wiklander jens.wiklander@linaro.org wrote:

...

Hi Sumit,

On Thu, Jun 13, 2019 at 04:00:29PM +0530, Sumit Garg wrote:

...

There are use-cases where user-space shouldn't be allowed to communicate directly with a TEE device which is dedicated to provide a specific service for a kernel client. So add a private login method for kernel clients and disallow user-space to open-session using this login method.

Signed-off-by: Sumit Garg sumit.garg@linaro.org

drivers/tee/tee_core.c | 6 ++++++ include/uapi/linux/tee.h | 2 ++ 2 files changed, 8 insertions(+)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c index 0f16d9f..4581bd1 100644 --- a/drivers/tee/tee_core.c +++ b/drivers/tee/tee_core.c @@ -334,6 +334,12 @@ static int tee_ioctl_open_session(struct tee_context *ctx, goto out; }

• if (arg.clnt_login == TEE_IOCTL_LOGIN_REE_KERNEL) {
  

TEE_IOCTL_LOGIN_REE_KERNEL is defined as 0x80000000 which is in the range specified and implementation defined by the GP spec. I wonder if we shouldn't filter the entire implementation defined range instead of just this value.

Agree. Will rather check for entire implementation defined range: 0x80000000 - 0xFFFFFFFF.

I had a second thought on this. It would be more restrictive for user-space TEE client library which may need to use implementation defined login method. So either we could define specific ranges for kernel and user-space or we can start with single login method reserved for kernel.

I think we should reserve a range for kernel internal use. Only reserving a single single login for kernel could force us to restrict the API once more later, better to take a chunk now and be done with it. Half of 0x80000000 - 0xFFFFFFFF is probably more than enough too to leave a range for user space too.

...

...

...

...

•         pr_err("login method not allowed for user-space client\n");
  

pr_debug(), if it's needed at all.

Ok will use pr_debug() instead.

...

...

•         rc = -EPERM;
  

•         goto out;
  

• }
  

• rc = ctx->teedev->desc->ops->open_session(ctx, &arg, params);
  if (rc)
          goto out;
  

diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h index 4b9eb06..f33c69c 100644 --- a/include/uapi/linux/tee.h +++ b/include/uapi/linux/tee.h @@ -172,6 +172,8 @@ struct tee_ioctl_buf_data { #define TEE_IOCTL_LOGIN_APPLICATION 4 #define TEE_IOCTL_LOGIN_USER_APPLICATION 5 #define TEE_IOCTL_LOGIN_GROUP_APPLICATION 6 +/* Private login method for REE kernel clients */

It's worth noting that this is filtered by the TEE framework, compared to everything else which is treated opaquely.

IIUC, you are referring to login filter in optee_os. Change to prevent filter for this login method is part of this PR [1].

[1] https://github.com/OP-TEE/optee_os/pull/3082

No, I was referring to the changes in tee_ioctl_open_session() above. It's relevant for user space to know since it will be prevented from using that range of login identifiers.

Ok, so you mean to extend the comment here for user-space to know that this login method/range is filtered by the TEE framework. Will do that.

...

This will restrict the user space API, but I think the risk of breakage is minimal as OP-TEE is the only in-tree driver registering in the TEE framework. I'm not aware of any out-of-tree drivers registering.

I am not sure if I follow you here. How do you expect this change to break out-of-tree TEE driver registration?

It's a change in common code that put restrictions on the API.

Thanks, Jens

-Sumit

...

Thanks, Jens

...

-Sumit

...

...

+#define TEE_IOCTL_LOGIN_REE_KERNEL 0x80000000

/**

• struct tee_ioctl_param - parameter

-- 2.7.4

Thanks, Jens