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author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-05-19 09:21:36 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-05-19 09:21:36 -0700 |
commit | f4f27d0028aabce57e44c16c2fdefccd6310d2f3 (patch) | |
tree | 09f25601316d22b64165c19042da51c101bde3c4 /Documentation | |
parent | 2600a46ee0ed57c0e0a382c2a37ebac64d374d20 (diff) | |
parent | b937190c40de0f6f07f592042e3097b16c6b0130 (diff) | |
download | linux-f4f27d0028aabce57e44c16c2fdefccd6310d2f3.tar.gz linux-f4f27d0028aabce57e44c16c2fdefccd6310d2f3.tar.bz2 linux-f4f27d0028aabce57e44c16c2fdefccd6310d2f3.zip |
Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull security subsystem updates from James Morris:
"Highlights:
- A new LSM, "LoadPin", from Kees Cook is added, which allows forcing
of modules and firmware to be loaded from a specific device (this
is from ChromeOS, where the device as a whole is verified
cryptographically via dm-verity).
This is disabled by default but can be configured to be enabled by
default (don't do this if you don't know what you're doing).
- Keys: allow authentication data to be stored in an asymmetric key.
Lots of general fixes and updates.
- SELinux: add restrictions for loading of kernel modules via
finit_module(). Distinguish non-init user namespace capability
checks. Apply execstack check on thread stacks"
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (48 commits)
LSM: LoadPin: provide enablement CONFIG
Yama: use atomic allocations when reporting
seccomp: Fix comment typo
ima: add support for creating files using the mknodat syscall
ima: fix ima_inode_post_setattr
vfs: forbid write access when reading a file into memory
fs: fix over-zealous use of "const"
selinux: apply execstack check on thread stacks
selinux: distinguish non-init user namespace capability checks
LSM: LoadPin for kernel file loading restrictions
fs: define a string representation of the kernel_read_file_id enumeration
Yama: consolidate error reporting
string_helpers: add kstrdup_quotable_file
string_helpers: add kstrdup_quotable_cmdline
string_helpers: add kstrdup_quotable
selinux: check ss_initialized before revalidating an inode label
selinux: delay inode label lookup as long as possible
selinux: don't revalidate an inode's label when explicitly setting it
selinux: Change bool variable name to index.
KEYS: Add KEYCTL_DH_COMPUTE command
...
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/security/LoadPin.txt | 17 | ||||
-rw-r--r-- | Documentation/security/keys.txt | 52 |
2 files changed, 69 insertions, 0 deletions
diff --git a/Documentation/security/LoadPin.txt b/Documentation/security/LoadPin.txt new file mode 100644 index 000000000000..e11877f5d3d4 --- /dev/null +++ b/Documentation/security/LoadPin.txt @@ -0,0 +1,17 @@ +LoadPin is a Linux Security Module that ensures all kernel-loaded files +(modules, firmware, etc) all originate from the same filesystem, with +the expectation that such a filesystem is backed by a read-only device +such as dm-verity or CDROM. This allows systems that have a verified +and/or unchangeable filesystem to enforce module and firmware loading +restrictions without needing to sign the files individually. + +The LSM is selectable at build-time with CONFIG_SECURITY_LOADPIN, and +can be controlled at boot-time with the kernel command line option +"loadpin.enabled". By default, it is enabled, but can be disabled at +boot ("loadpin.enabled=0"). + +LoadPin starts pinning when it sees the first file loaded. If the +block device backing the filesystem is not read-only, a sysctl is +created to toggle pinning: /proc/sys/kernel/loadpin/enabled. (Having +a mutable filesystem means pinning is mutable too, but having the +sysctl allows for easy testing on systems with a mutable filesystem.) diff --git a/Documentation/security/keys.txt b/Documentation/security/keys.txt index 8c183873b2b7..20d05719bceb 100644 --- a/Documentation/security/keys.txt +++ b/Documentation/security/keys.txt @@ -823,6 +823,36 @@ The keyctl syscall functions are: A process must have search permission on the key for this function to be successful. + (*) Compute a Diffie-Hellman shared secret or public key + + long keyctl(KEYCTL_DH_COMPUTE, struct keyctl_dh_params *params, + char *buffer, size_t buflen); + + The params struct contains serial numbers for three keys: + + - The prime, p, known to both parties + - The local private key + - The base integer, which is either a shared generator or the + remote public key + + The value computed is: + + result = base ^ private (mod prime) + + If the base is the shared generator, the result is the local + public key. If the base is the remote public key, the result is + the shared secret. + + The buffer length must be at least the length of the prime, or zero. + + If the buffer length is nonzero, the length of the result is + returned when it is successfully calculated and copied in to the + buffer. When the buffer length is zero, the minimum required + buffer length is returned. + + This function will return error EOPNOTSUPP if the key type is not + supported, error ENOKEY if the key could not be found, or error + EACCES if the key is not readable by the caller. =============== KERNEL SERVICES @@ -999,6 +1029,10 @@ payload contents" for more information. struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, const struct cred *cred, key_perm_t perm, + int (*restrict_link)(struct key *, + const struct key_type *, + unsigned long, + const union key_payload *), unsigned long flags, struct key *dest); @@ -1010,6 +1044,24 @@ payload contents" for more information. KEY_ALLOC_NOT_IN_QUOTA in flags if the keyring shouldn't be accounted towards the user's quota). Error ENOMEM can also be returned. + If restrict_link not NULL, it should point to a function that will be + called each time an attempt is made to link a key into the new keyring. + This function is called to check whether a key may be added into the keying + or not. Callers of key_create_or_update() within the kernel can pass + KEY_ALLOC_BYPASS_RESTRICTION to suppress the check. An example of using + this is to manage rings of cryptographic keys that are set up when the + kernel boots where userspace is also permitted to add keys - provided they + can be verified by a key the kernel already has. + + When called, the restriction function will be passed the keyring being + added to, the key flags value and the type and payload of the key being + added. Note that when a new key is being created, this is called between + payload preparsing and actual key creation. The function should return 0 + to allow the link or an error to reject it. + + A convenience function, restrict_link_reject, exists to always return + -EPERM to in this case. + (*) To check the validity of a key, this function can be called: |