From 5395d312dff00d9e94702d28fe1e08dacd1cbe31 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Sat, 13 May 2017 04:51:53 -0700 Subject: doc: ReSTify keys-trusted-encrypted.txt Adjusts for ReST markup and moves under keys security devel index. Cc: David Howells Cc: Mimi Zohar Signed-off-by: Kees Cook Signed-off-by: Jonathan Corbet --- Documentation/security/00-INDEX | 4 - Documentation/security/conf.py | 8 - Documentation/security/keys-trusted-encrypted.txt | 167 --------------------- Documentation/security/keys/index.rst | 1 + Documentation/security/keys/trusted-encrypted.rst | 175 ++++++++++++++++++++++ 5 files changed, 176 insertions(+), 179 deletions(-) delete mode 100644 Documentation/security/00-INDEX delete mode 100644 Documentation/security/conf.py delete mode 100644 Documentation/security/keys-trusted-encrypted.txt create mode 100644 Documentation/security/keys/trusted-encrypted.rst (limited to 'Documentation/security') diff --git a/Documentation/security/00-INDEX b/Documentation/security/00-INDEX deleted file mode 100644 index c8dbbc227326..000000000000 --- a/Documentation/security/00-INDEX +++ /dev/null @@ -1,4 +0,0 @@ -00-INDEX - - this file. -keys-trusted-encrypted.txt - - info on the Trusted and Encrypted keys in the kernel key ring service. diff --git a/Documentation/security/conf.py b/Documentation/security/conf.py deleted file mode 100644 index 472fc9a8eb67..000000000000 --- a/Documentation/security/conf.py +++ /dev/null @@ -1,8 +0,0 @@ -project = "The kernel security subsystem manual" - -tags.add("subproject") - -latex_documents = [ - ('index', 'security.tex', project, - 'The kernel development community', 'manual'), -] diff --git a/Documentation/security/keys-trusted-encrypted.txt b/Documentation/security/keys-trusted-encrypted.txt deleted file mode 100644 index b20a993a32af..000000000000 --- a/Documentation/security/keys-trusted-encrypted.txt +++ /dev/null @@ -1,167 +0,0 @@ - Trusted and Encrypted Keys - -Trusted and Encrypted Keys are two new key types added to the existing kernel -key ring service. Both of these new types are variable length symmetric keys, -and in both cases all keys are created in the kernel, and user space sees, -stores, and loads only encrypted blobs. Trusted Keys require the availability -of a Trusted Platform Module (TPM) chip for greater security, while Encrypted -Keys can be used on any system. All user level blobs, are displayed and loaded -in hex ascii for convenience, and are integrity verified. - -Trusted Keys use a TPM both to generate and to seal the keys. Keys are sealed -under a 2048 bit RSA key in the TPM, and optionally sealed to specified PCR -(integrity measurement) values, and only unsealed by the TPM, if PCRs and blob -integrity verifications match. A loaded Trusted Key can be updated with new -(future) PCR values, so keys are easily migrated to new pcr values, such as -when the kernel and initramfs are updated. The same key can have many saved -blobs under different PCR values, so multiple boots are easily supported. - -By default, trusted keys are sealed under the SRK, which has the default -authorization value (20 zeros). This can be set at takeownership time with the -trouser's utility: "tpm_takeownership -u -z". - -Usage: - keyctl add trusted name "new keylen [options]" ring - keyctl add trusted name "load hex_blob [pcrlock=pcrnum]" ring - keyctl update key "update [options]" - keyctl print keyid - - options: - keyhandle= ascii hex value of sealing key default 0x40000000 (SRK) - keyauth= ascii hex auth for sealing key default 0x00...i - (40 ascii zeros) - blobauth= ascii hex auth for sealed data default 0x00... - (40 ascii zeros) - pcrinfo= ascii hex of PCR_INFO or PCR_INFO_LONG (no default) - pcrlock= pcr number to be extended to "lock" blob - migratable= 0|1 indicating permission to reseal to new PCR values, - default 1 (resealing allowed) - hash= hash algorithm name as a string. For TPM 1.x the only - allowed value is sha1. For TPM 2.x the allowed values - are sha1, sha256, sha384, sha512 and sm3-256. - policydigest= digest for the authorization policy. must be calculated - with the same hash algorithm as specified by the 'hash=' - option. - policyhandle= handle to an authorization policy session that defines the - same policy and with the same hash algorithm as was used to - seal the key. - -"keyctl print" returns an ascii hex copy of the sealed key, which is in standard -TPM_STORED_DATA format. The key length for new keys are always in bytes. -Trusted Keys can be 32 - 128 bytes (256 - 1024 bits), the upper limit is to fit -within the 2048 bit SRK (RSA) keylength, with all necessary structure/padding. - -Encrypted keys do not depend on a TPM, and are faster, as they use AES for -encryption/decryption. New keys are created from kernel generated random -numbers, and are encrypted/decrypted using a specified 'master' key. The -'master' key can either be a trusted-key or user-key type. The main -disadvantage of encrypted keys is that if they are not rooted in a trusted key, -they are only as secure as the user key encrypting them. The master user key -should therefore be loaded in as secure a way as possible, preferably early in -boot. - -The decrypted portion of encrypted keys can contain either a simple symmetric -key or a more complex structure. The format of the more complex structure is -application specific, which is identified by 'format'. - -Usage: - keyctl add encrypted name "new [format] key-type:master-key-name keylen" - ring - keyctl add encrypted name "load hex_blob" ring - keyctl update keyid "update key-type:master-key-name" - -format:= 'default | ecryptfs' -key-type:= 'trusted' | 'user' - - -Examples of trusted and encrypted key usage: - -Create and save a trusted key named "kmk" of length 32 bytes: - - $ keyctl add trusted kmk "new 32" @u - 440502848 - - $ keyctl show - Session Keyring - -3 --alswrv 500 500 keyring: _ses - 97833714 --alswrv 500 -1 \_ keyring: _uid.500 - 440502848 --alswrv 500 500 \_ trusted: kmk - - $ keyctl print 440502848 - 0101000000000000000001005d01b7e3f4a6be5709930f3b70a743cbb42e0cc95e18e915 - 3f60da455bbf1144ad12e4f92b452f966929f6105fd29ca28e4d4d5a031d068478bacb0b - 27351119f822911b0a11ba3d3498ba6a32e50dac7f32894dd890eb9ad578e4e292c83722 - a52e56a097e6a68b3f56f7a52ece0cdccba1eb62cad7d817f6dc58898b3ac15f36026fec - d568bd4a706cb60bb37be6d8f1240661199d640b66fb0fe3b079f97f450b9ef9c22c6d5d - dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471dc6d13ecf8298b946f65345faa5ef0 - f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b - e4a8aea2b607ec96931e6f4d4fe563ba - - $ keyctl pipe 440502848 > kmk.blob - -Load a trusted key from the saved blob: - - $ keyctl add trusted kmk "load `cat kmk.blob`" @u - 268728824 - - $ keyctl print 268728824 - 0101000000000000000001005d01b7e3f4a6be5709930f3b70a743cbb42e0cc95e18e915 - 3f60da455bbf1144ad12e4f92b452f966929f6105fd29ca28e4d4d5a031d068478bacb0b - 27351119f822911b0a11ba3d3498ba6a32e50dac7f32894dd890eb9ad578e4e292c83722 - a52e56a097e6a68b3f56f7a52ece0cdccba1eb62cad7d817f6dc58898b3ac15f36026fec - d568bd4a706cb60bb37be6d8f1240661199d640b66fb0fe3b079f97f450b9ef9c22c6d5d - dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471dc6d13ecf8298b946f65345faa5ef0 - f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b - e4a8aea2b607ec96931e6f4d4fe563ba - -Reseal a trusted key under new pcr values: - - $ keyctl update 268728824 "update pcrinfo=`cat pcr.blob`" - $ keyctl print 268728824 - 010100000000002c0002800093c35a09b70fff26e7a98ae786c641e678ec6ffb6b46d805 - 77c8a6377aed9d3219c6dfec4b23ffe3000001005d37d472ac8a44023fbb3d18583a4f73 - d3a076c0858f6f1dcaa39ea0f119911ff03f5406df4f7f27f41da8d7194f45c9f4e00f2e - df449f266253aa3f52e55c53de147773e00f0f9aca86c64d94c95382265968c354c5eab4 - 9638c5ae99c89de1e0997242edfb0b501744e11ff9762dfd951cffd93227cc513384e7e6 - e782c29435c7ec2edafaa2f4c1fe6e7a781b59549ff5296371b42133777dcc5b8b971610 - 94bc67ede19e43ddb9dc2baacad374a36feaf0314d700af0a65c164b7082401740e489c9 - 7ef6a24defe4846104209bf0c3eced7fa1a672ed5b125fc9d8cd88b476a658a4434644ef - df8ae9a178e9f83ba9f08d10fa47e4226b98b0702f06b3b8 - -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 -trusted key provides strong guarantees that the EVM key has not been -compromised by a user level problem, and when sealed to specific boot PCR -values, protects against boot and offline attacks. 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 - 159771175 - -option 2: explicitly defining 'format' as 'default' - $ keyctl add encrypted evm "new default trusted:kmk 32" @u - 159771175 - - $ keyctl print 159771175 - default trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3 - 82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0 - 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc - - $ keyctl pipe 159771175 > 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 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3 - 82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0 - 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc - -Other uses for trusted and encrypted keys, such as for disk and file encryption -are anticipated. In particular the new format 'ecryptfs' has been defined in -in order to use encrypted keys to mount an eCryptfs filesystem. More details -about the usage can be found in the file -'Documentation/security/keys-ecryptfs.txt'. diff --git a/Documentation/security/keys/index.rst b/Documentation/security/keys/index.rst index d7ddbc1c2502..647d58f2588e 100644 --- a/Documentation/security/keys/index.rst +++ b/Documentation/security/keys/index.rst @@ -8,3 +8,4 @@ Kernel Keys core ecryptfs request-key + trusted-encrypted diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst new file mode 100644 index 000000000000..7b503831bdea --- /dev/null +++ b/Documentation/security/keys/trusted-encrypted.rst @@ -0,0 +1,175 @@ +========================== +Trusted and Encrypted Keys +========================== + +Trusted and Encrypted Keys are two new key types added to the existing kernel +key ring service. Both of these new types are variable length symmetric keys, +and in both cases all keys are created in the kernel, and user space sees, +stores, and loads only encrypted blobs. Trusted Keys require the availability +of a Trusted Platform Module (TPM) chip for greater security, while Encrypted +Keys can be used on any system. All user level blobs, are displayed and loaded +in hex ascii for convenience, and are integrity verified. + +Trusted Keys use a TPM both to generate and to seal the keys. Keys are sealed +under a 2048 bit RSA key in the TPM, and optionally sealed to specified PCR +(integrity measurement) values, and only unsealed by the TPM, if PCRs and blob +integrity verifications match. A loaded Trusted Key can be updated with new +(future) PCR values, so keys are easily migrated to new pcr values, such as +when the kernel and initramfs are updated. The same key can have many saved +blobs under different PCR values, so multiple boots are easily supported. + +By default, trusted keys are sealed under the SRK, which has the default +authorization value (20 zeros). This can be set at takeownership time with the +trouser's utility: "tpm_takeownership -u -z". + +Usage:: + + keyctl add trusted name "new keylen [options]" ring + keyctl add trusted name "load hex_blob [pcrlock=pcrnum]" ring + keyctl update key "update [options]" + keyctl print keyid + + options: + keyhandle= ascii hex value of sealing key default 0x40000000 (SRK) + keyauth= ascii hex auth for sealing key default 0x00...i + (40 ascii zeros) + blobauth= ascii hex auth for sealed data default 0x00... + (40 ascii zeros) + pcrinfo= ascii hex of PCR_INFO or PCR_INFO_LONG (no default) + pcrlock= pcr number to be extended to "lock" blob + migratable= 0|1 indicating permission to reseal to new PCR values, + default 1 (resealing allowed) + hash= hash algorithm name as a string. For TPM 1.x the only + allowed value is sha1. For TPM 2.x the allowed values + are sha1, sha256, sha384, sha512 and sm3-256. + policydigest= digest for the authorization policy. must be calculated + with the same hash algorithm as specified by the 'hash=' + option. + policyhandle= handle to an authorization policy session that defines the + same policy and with the same hash algorithm as was used to + seal the key. + +"keyctl print" returns an ascii hex copy of the sealed key, which is in standard +TPM_STORED_DATA format. The key length for new keys are always in bytes. +Trusted Keys can be 32 - 128 bytes (256 - 1024 bits), the upper limit is to fit +within the 2048 bit SRK (RSA) keylength, with all necessary structure/padding. + +Encrypted keys do not depend on a TPM, and are faster, as they use AES for +encryption/decryption. New keys are created from kernel generated random +numbers, and are encrypted/decrypted using a specified 'master' key. The +'master' key can either be a trusted-key or user-key type. The main +disadvantage of encrypted keys is that if they are not rooted in a trusted key, +they are only as secure as the user key encrypting them. The master user key +should therefore be loaded in as secure a way as possible, preferably early in +boot. + +The decrypted portion of encrypted keys can contain either a simple symmetric +key or a more complex structure. The format of the more complex structure is +application specific, which is identified by 'format'. + +Usage:: + + keyctl add encrypted name "new [format] key-type:master-key-name keylen" + ring + keyctl add encrypted name "load hex_blob" ring + keyctl update keyid "update key-type:master-key-name" + +Where:: + + format:= 'default | ecryptfs' + key-type:= 'trusted' | 'user' + + +Examples of trusted and encrypted key usage: + +Create and save a trusted key named "kmk" of length 32 bytes:: + + $ keyctl add trusted kmk "new 32" @u + 440502848 + + $ keyctl show + Session Keyring + -3 --alswrv 500 500 keyring: _ses + 97833714 --alswrv 500 -1 \_ keyring: _uid.500 + 440502848 --alswrv 500 500 \_ trusted: kmk + + $ keyctl print 440502848 + 0101000000000000000001005d01b7e3f4a6be5709930f3b70a743cbb42e0cc95e18e915 + 3f60da455bbf1144ad12e4f92b452f966929f6105fd29ca28e4d4d5a031d068478bacb0b + 27351119f822911b0a11ba3d3498ba6a32e50dac7f32894dd890eb9ad578e4e292c83722 + a52e56a097e6a68b3f56f7a52ece0cdccba1eb62cad7d817f6dc58898b3ac15f36026fec + d568bd4a706cb60bb37be6d8f1240661199d640b66fb0fe3b079f97f450b9ef9c22c6d5d + dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471dc6d13ecf8298b946f65345faa5ef0 + f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b + e4a8aea2b607ec96931e6f4d4fe563ba + + $ keyctl pipe 440502848 > kmk.blob + +Load a trusted key from the saved blob:: + + $ keyctl add trusted kmk "load `cat kmk.blob`" @u + 268728824 + + $ keyctl print 268728824 + 0101000000000000000001005d01b7e3f4a6be5709930f3b70a743cbb42e0cc95e18e915 + 3f60da455bbf1144ad12e4f92b452f966929f6105fd29ca28e4d4d5a031d068478bacb0b + 27351119f822911b0a11ba3d3498ba6a32e50dac7f32894dd890eb9ad578e4e292c83722 + a52e56a097e6a68b3f56f7a52ece0cdccba1eb62cad7d817f6dc58898b3ac15f36026fec + d568bd4a706cb60bb37be6d8f1240661199d640b66fb0fe3b079f97f450b9ef9c22c6d5d + dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471dc6d13ecf8298b946f65345faa5ef0 + f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b + e4a8aea2b607ec96931e6f4d4fe563ba + +Reseal a trusted key under new pcr values:: + + $ keyctl update 268728824 "update pcrinfo=`cat pcr.blob`" + $ keyctl print 268728824 + 010100000000002c0002800093c35a09b70fff26e7a98ae786c641e678ec6ffb6b46d805 + 77c8a6377aed9d3219c6dfec4b23ffe3000001005d37d472ac8a44023fbb3d18583a4f73 + d3a076c0858f6f1dcaa39ea0f119911ff03f5406df4f7f27f41da8d7194f45c9f4e00f2e + df449f266253aa3f52e55c53de147773e00f0f9aca86c64d94c95382265968c354c5eab4 + 9638c5ae99c89de1e0997242edfb0b501744e11ff9762dfd951cffd93227cc513384e7e6 + e782c29435c7ec2edafaa2f4c1fe6e7a781b59549ff5296371b42133777dcc5b8b971610 + 94bc67ede19e43ddb9dc2baacad374a36feaf0314d700af0a65c164b7082401740e489c9 + 7ef6a24defe4846104209bf0c3eced7fa1a672ed5b125fc9d8cd88b476a658a4434644ef + df8ae9a178e9f83ba9f08d10fa47e4226b98b0702f06b3b8 + +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 +trusted key provides strong guarantees that the EVM key has not been +compromised by a user level problem, and when sealed to specific boot PCR +values, protects against boot and offline attacks. 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 + 159771175 + +option 2: explicitly defining 'format' as 'default':: + + $ keyctl add encrypted evm "new default trusted:kmk 32" @u + 159771175 + + $ keyctl print 159771175 + default trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3 + 82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0 + 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc + + $ keyctl pipe 159771175 > 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 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3 + 82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0 + 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc + +Other uses for trusted and encrypted keys, such as for disk and file encryption +are anticipated. In particular the new format 'ecryptfs' has been defined in +in order to use encrypted keys to mount an eCryptfs filesystem. More details +about the usage can be found in the file +``Documentation/security/keys-ecryptfs.txt``. -- cgit v1.2.3