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author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-10 11:18:59 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-10 11:18:59 -0800 |
commit | e0e736fc0d33861335e2a132e4f688f7fd380c61 (patch) | |
tree | d9febe9ca1ef1e24efc5e6e1e34e412316d246bd /Documentation | |
parent | a08948812b30653eb2c536ae613b635a989feb6f (diff) | |
parent | aeda4ac3efc29e4d55989abd0a73530453aa69ba (diff) | |
download | linux-e0e736fc0d33861335e2a132e4f688f7fd380c61.tar.gz linux-e0e736fc0d33861335e2a132e4f688f7fd380c61.tar.xz |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6: (30 commits)
MAINTAINERS: Add tomoyo-dev-en ML.
SELinux: define permissions for DCB netlink messages
encrypted-keys: style and other cleanup
encrypted-keys: verify datablob size before converting to binary
trusted-keys: kzalloc and other cleanup
trusted-keys: additional TSS return code and other error handling
syslog: check cap_syslog when dmesg_restrict
Smack: Transmute labels on specified directories
selinux: cache sidtab_context_to_sid results
SELinux: do not compute transition labels on mountpoint labeled filesystems
This patch adds a new security attribute to Smack called SMACK64EXEC. It defines label that is used while task is running.
SELinux: merge policydb_index_classes and policydb_index_others
selinux: convert part of the sym_val_to_name array to use flex_array
selinux: convert type_val_to_struct to flex_array
flex_array: fix flex_array_put_ptr macro to be valid C
SELinux: do not set automatic i_ino in selinuxfs
selinux: rework security_netlbl_secattr_to_sid
SELinux: standardize return code handling in selinuxfs.c
SELinux: standardize return code handling in selinuxfs.c
SELinux: standardize return code handling in policydb.c
...
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/keys-trusted-encrypted.txt | 145 | ||||
-rw-r--r-- | Documentation/sysctl/kernel.txt | 2 |
2 files changed, 146 insertions, 1 deletions
diff --git a/Documentation/keys-trusted-encrypted.txt b/Documentation/keys-trusted-encrypted.txt new file mode 100644 index 000000000000..8fb79bc1ac4b --- /dev/null +++ b/Documentation/keys-trusted-encrypted.txt @@ -0,0 +1,145 @@ + 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 symmetic 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) + 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) + +"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. + +Usage: + keyctl add encrypted name "new 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 'key-type' is either 'trusted' or '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 + +Create and save an encrypted key "evm" using the above trusted key "kmk": + + $ keyctl add encrypted evm "new trusted:kmk 32" @u + 159771175 + + $ keyctl print 159771175 + trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b382dbbc55 + be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e024717c64 + 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 + trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b382dbbc55 + be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e024717c64 + 5972dcb82ab2dde83376d82b2e3c09ffc + + +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. Other uses for trusted and +encrypted keys, such as for disk and file encryption are anticipated. diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index 209e1584c3dc..574067194f38 100644 --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -219,7 +219,7 @@ dmesg_restrict: This toggle indicates whether unprivileged users are prevented from using dmesg(8) to view messages from the kernel's log buffer. When dmesg_restrict is set to (0) there are no restrictions. When -dmesg_restrict is set set to (1), users must have CAP_SYS_ADMIN to use +dmesg_restrict is set set to (1), users must have CAP_SYSLOG to use dmesg(8). The kernel config option CONFIG_SECURITY_DMESG_RESTRICT sets the default |