(added CAAM maintainers) On Mon, Apr 09, 2018 at 03:10:11PM +0100, Martin Townsend wrote: > Hi Mimi, > > On Mon, Apr 9, 2018 at 1:46 PM, Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx> wrote: > > On Mon, 2018-04-09 at 09:41 +0100, Martin Townsend wrote: > >> Hi, > >> > >> I'm trying to get to the bottom of an issue I'm seeing when enabling > >> the CAAM in the kernel with IMA/EVM enabled. I'm using the official > >> NXP (imx_4.9.11_1.0.0_ga) vendor Kernel. > >> [ snip ] > I think the integrity error message is a side effect of the previous > error, ie we are getting this error message because the CAAM is > failing to verify the certificates signature and hence IMA fails to > load the certificate onto the keyring. If I disable CAAM then > everything works as expected. What I'm trying to get to the bottom of > is why CAAM is failing to verify the signature. Further below in the > email I have determined that the signature is 257 bytes do you think > this is correct? I've read a post here: > https://crypto.stackexchange.com/questions/3505/what-is-the-length-of-an-rsa-signature > > That says that for PKCS#1 the signature should always be of the size > of the modulus, then it goes on to say: "In some protocols, there can > be some wrapping around the signature, e.g. to indicate which > algorithm was used," I'm wondering if that's what I'm seeing, an > extra byte in the signature that is the type of algorithm used but > this extra byte is also passed to the CAAM and causes it to fail as > then the signature is now larger than the modulus. But I don't know > what I can do about this, I'm not even sure what protocol is being > used to generate this extra byte, any suggestions on how to find this > out would be appreciated. I don't really understand crypto and I maybe talking complete nonsense, but judging by diffstat between the imx_4.9.11_1.0.0_ga and mainline, the CAAM driver had a lot of additions since then :) The caam_rsa_dec function gained form 2 and form of 3 RSA decoding. That might explain your issue... > > > > > >> I put a dump_stack in the error handling routine in CAAM and in the > >> caam_jr_enqueue to get (I removed some of the caam_jr_enqueue > >> dump_stacks during initialisation to highlight the one of interest) Does any of the other caam_jr_enqueue stacks include load_system_certificate_list() call? If you have a x509 certificate built into the kernel I presume it will also pass through caam_rsa_dec. You can also try using the built-in certificate as IMA x509 certificate and see if it changes anything. > >> caam 2140000.caam: ERA source: CCBVID. > >> caam 2140000.caam: Entropy delay = 3200 > >> caam 2140000.caam: Instantiated RNG4 SH0 > >> caam 2140000.caam: Instantiated RNG4 SH1 > >> caam 2140000.caam: device ID = 0x0a16030000000000 (Era 8) > >> caam 2140000.caam: job rings = 3, qi = 0 > >> caam algorithms registered in /proc/crypto > >> caam_jr_enqueue > >> CPU: 0 PID: 1 Comm: swapper Not tainted 4.9.11-1.0.0+gc27010d #4 > >> Hardware name: Freescale i.MX6 UltraLite (Device Tree) > >> caam_jr_enqueue > >> CPU: 0 PID: 1 Comm: swapper Not tainted 4.9.11-1.0.0+gc27010d #4 > >> Hardware name: Freescale i.MX6 UltraLite (Device Tree) > >> caam_jr 2141000.jr0: registering rng-caam > >> caam 2140000.caam: caam pkc algorithms registered in /proc/crypto > >> caam_jr_enqueue > >> CPU: 0 PID: 1 Comm: swapper Not tainted 4.9.11-1.0.0+gc27010d #4 > >> Hardware name: Freescale i.MX6 UltraLite (Device Tree) > >> caam_rsa_set_pub_key > >> caam_rsa_max_size > >> caam_rsa_enc > >> caam_jr_enqueue > >> CPU: 0 PID: 1 Comm: swapper Not tainted 4.9.11-1.0.0+gc27010d #4 > >> Hardware name: Freescale i.MX6 UltraLite (Device Tree) > >> [<8010dd8c>] (unwind_backtrace) from [<8010b8cc>] (show_stack+0x10/0x14) > >> [<8010b8cc>] (show_stack) from [<80608f74>] (caam_jr_enqueue+0x3c/0x2bc) > >> [<80608f74>] (caam_jr_enqueue) from [<8061fb84>] (caam_rsa_enc+0x210/0x3ac) > >> [<8061fb84>] (caam_rsa_enc) from [<803ed910>] (pkcs1pad_verify+0xa8/0xe4) > >> [<803ed910>] (pkcs1pad_verify) from [<804134e4>] > >> (public_key_verify_signature+0x17c/0x248) > >> [<804134e4>] (public_key_verify_signature) from [<804132a0>] > >> (restrict_link_by_signature+0xa8/0xd4) > >> [<804132a0>] (restrict_link_by_signature) from [<803cadd4>] > >> (key_create_or_update+0x12c/0x370) > >> [<803cadd4>] (key_create_or_update) from [<80c253a0>] > >> (integrity_load_x509+0x70/0xc4) > >> [<80c253a0>] (integrity_load_x509) from [<80c256bc>] (ima_load_x509+0x28/0x3c) > >> [<80c256bc>] (ima_load_x509) from [<80c2510c>] (integrity_load_keys+0x8/0x10) > >> [<80c2510c>] (integrity_load_keys) from [<80c00de0>] > >> (kernel_init_freeable+0x1bc/0x1cc) > >> [<80c00de0>] (kernel_init_freeable) from [<80844ccc>] (kernel_init+0x8/0x114) > >> [<80844ccc>] (kernel_init) from [<801078d8>] (ret_from_fork+0x14/0x3c) > >> CPU: 0 PID: 112 Comm: irq/214-2142000 Not tainted 4.9.11-1.0.0+gc27010d #4 > >> Hardware name: Freescale i.MX6 UltraLite (Device Tree) > >> [<8010dd8c>] (unwind_backtrace) from [<8010b8cc>] (show_stack+0x10/0x14) > >> [<8010b8cc>] (show_stack) from [<8060a0e8>] (report_deco_status+0x30/0xf8) > >> [<8060a0e8>] (report_deco_status) from [<8061f3c8>] (rsa_pub_done+0x20/0x60) > >> [<8061f3c8>] (rsa_pub_done) from [<80608d94>] (caam_jr_threadirq+0x1dc/0x29c) > >> [<80608d94>] (caam_jr_threadirq) from [<80165dcc>] (irq_thread_fn+0x1c/0x54) > >> [<80165dcc>] (irq_thread_fn) from [<80166024>] (irq_thread+0x114/0x1d4) > >> [<80166024>] (irq_thread) from [<801415b4>] (kthread+0xe4/0xec) > >> [<801415b4>] (kthread) from [<801078d8>] (ret_from_fork+0x14/0x3c) > >> caam_jr 2142000.jr1: 40000789: DECO: desc idx 7: Protocol Size Error - > >> A protocol has seen an error in size. When running RSA, pdb size N < > >> (size of F) when no formatting is used; or pdb size N < (F + 11) when > >> formatting is used. > >> integrity: Problem loading X.509 certificate (-129): /etc/keys/ima-x509.der > >> [<8010dd8c>] (unwind_backtrace) from [<8010b8cc>] (show_stack+0x10/0x14) > >> [<8010b8cc>] (show_stack) from [<8060a0d0>] (report_deco_status+0x30/0xf8) > >> [<8060a0d0>] (report_deco_status) from [<8061db94>] (rsa_pub_done+0x20/0x60) > >> [<8061db94>] (rsa_pub_done) from [<80608d94>] (caam_jr_threadirq+0x1dc/0x29c) > >> [<80608d94>] (caam_jr_threadirq) from [<80165dcc>] (irq_thread_fn+0x1c/0x54) > >> [<80165dcc>] (irq_thread_fn) from [<80166024>] (irq_thread+0x114/0x1d4) > >> [<80166024>] (irq_thread) from [<801415b4>] (kthread+0xe4/0xec) > >> [<801415b4>] (kthread) from [<801078d8>] (ret_from_fork+0x14/0x3c) > >> > >> So it's failing to verify the signature on my x509 certificate because > >> pdb size M < (size of F) ... > >> > >> On the NXP mailing lists there is someone with a similar issue and the > >> response was > >> “The error appears to be saying that the public RSA modulus is shorter > >> than the signature being verified. > >> > >> RSA uses modular arithmetic, and all valid values are smaller than the > >> public RSA modulus. However, the signature (F in the error message > >> below), is too large. > >> > >> The customer should try to determine why their public RSA Modulus (N) > >> is shorter than the signature (F).” > >> > >> I have to admit I'm not really sure what this means, I've created my > >> certificate using openssl and a configuration file (shown below) that > >> set the keysize to 2048 bits so I'm not sure how the signature in the > >> x509 is greater than the RSA modulus which in my limited understanding > >> is the key size in bits. > >> > >> I added the following to public_key_verify_signature() > >> > >> printk("%s: Public Key: Keylen: %u\n", __func__, pkey->keylen); > >> printk("%s: Signature: %u\n", __func__, sig->s_size); > >> > >> and get > >> > >> public_key_verify_signature: Public Key: Keylen: 270 > >> public_key_verify_signature: Signature: 257 > >> > >> I'm assuming they are both in bytes which kind of suggests the key > >> length is larger than the signature but then again this keylen may > >> include other information. I'm a bit suspicious of the signature > >> length of 257 maybe this is causing the problem which could point to > >> creating the certificate incorrectly?? Here's the configuration I'm > >> using for the root cert: > >> [ ca ] > >> default_ca = CA_default > >> > >> [ CA_default ] > >> dir = ./ca > >> > >> certs = $dir/certsdb # > >> Where the issued certs are kept > >> new_certs_dir = $certs # > >> default place for new certs. > >> database = $dir/certdbindex.txt # > >> database index file. > >> certificate = $dir/certs/ima-local-ca.x509 # The > >> CA certificate > >> private_key = $dir/private/ca-privkey.pem # The > >> private key > >> default_days = 3650 > >> default_md = sha256 > >> preserve = no > >> email_in_dn = no > >> nameopt = default_ca > >> certopt = default_ca > >> policy = policy_ima_ca > >> > >> [ policy_ima_ca ] > >> countryName = match # Must be > >> the same as the CA > >> stateOrProvinceName = match # Must be > >> the same as the CA > >> organizationName = supplied > >> organizationalUnitName = optional > >> commonName = supplied # Must be there > >> emailAddress = optional > >> > >> [ req ] > >> default_bits = 2048 # Size of keys > >> default_keyfile = privkey.pem # name of > >> generated keys > >> string_mask = utf8only # permitted characters > >> distinguished_name = req_distinguished_name # where to > >> get DN for reqs > >> prompt = no # No prompting > >> x509_extensions = v3_ca # The > >> extentions to add to self signed certs > >> req_extensions = v3_req # The > >> extensions to add to req's > >> > >> [ req_distinguished_name ] > >> O = xxx > >> OU = IMA > >> CN = xxx IMA-EVM Root CA > >> emailAddress = ca-ima-evm@xxxxxxx > >> L = xxx > >> ST = Dorset > >> C = xxx > >> > >> [ v3_ca ] > >> basicConstraints = CA:TRUE > >> subjectKeyIdentifier = hash > >> authorityKeyIdentifier = keyid:always,issuer:always > >> subjectAltName = email:move > >> > >> [ v3_req ] > >> subjectAltName=email:move > >> > >> > >> Then the openssl (1.0.2n 7 Dec 2017) command to create the self > >> signed root CA certificate. > >> > >> openssl req -new -x509 -utf8 -sha256 \ > >> -days $((365 * $duration)) \ > >> -passout file:$rootcadir/private/key_pass.txt \ > >> -keyout $rootca_privkey \ > >> -outform DER \ > >> -out $rootca_pubcert_der \ > >> -config $rootcadir/$ima_root_openssl_cnf > >> > >> I'm not sure what I can do further to debug this so any help or > >> suggestions would be really appreciated. If there is any further > >> debug that would help let me know and I'll try it out. > >> > >> Many Thanks, > >> Martin. > >> > > > -- Sincerely yours, Mike.
