diff options
Diffstat (limited to 'Documentation/security')
| -rw-r--r-- | Documentation/security/LSM.txt | 7 | ||||
| -rw-r--r-- | Documentation/security/keys.txt | 17 | ||||
| -rw-r--r-- | Documentation/security/self-protection.txt | 10 |
3 files changed, 30 insertions, 4 deletions
diff --git a/Documentation/security/LSM.txt b/Documentation/security/LSM.txt index 3db7e671c440..c2683f28ed36 100644 --- a/Documentation/security/LSM.txt +++ b/Documentation/security/LSM.txt @@ -22,6 +22,13 @@ system, building their checks on top of the defined capability hooks. For more details on capabilities, see capabilities(7) in the Linux man-pages project. +A list of the active security modules can be found by reading +/sys/kernel/security/lsm. This is a comma separated list, and +will always include the capability module. The list reflects the +order in which checks are made. The capability module will always +be first, followed by any "minor" modules (e.g. Yama) and then +the one "major" module (e.g. SELinux) if there is one configured. + Based on https://lkml.org/lkml/2007/10/26/215, a new LSM is accepted into the kernel when its intent (a description of what it tries to protect against and in what cases one would expect to diff --git a/Documentation/security/keys.txt b/Documentation/security/keys.txt index 3849814bfe6d..0e03baf271bd 100644 --- a/Documentation/security/keys.txt +++ b/Documentation/security/keys.txt @@ -1151,8 +1151,21 @@ access the data: usage. This is called key->payload.rcu_data0. The following accessors wrap the RCU calls to this element: - rcu_assign_keypointer(struct key *key, void *data); - void *rcu_dereference_key(struct key *key); + (a) Set or change the first payload pointer: + + rcu_assign_keypointer(struct key *key, void *data); + + (b) Read the first payload pointer with the key semaphore held: + + [const] void *dereference_key_locked([const] struct key *key); + + Note that the return value will inherit its constness from the key + parameter. Static analysis will give an error if it things the lock + isn't held. + + (c) Read the first payload pointer with the RCU read lock held: + + const void *dereference_key_rcu(const struct key *key); =================== diff --git a/Documentation/security/self-protection.txt b/Documentation/security/self-protection.txt index 3010576c9fca..141acfebe6ef 100644 --- a/Documentation/security/self-protection.txt +++ b/Documentation/security/self-protection.txt @@ -51,11 +51,17 @@ kernel, they are implemented in a way where the memory is temporarily made writable during the update, and then returned to the original permissions.) -In support of this are (the poorly named) CONFIG_DEBUG_RODATA and -CONFIG_DEBUG_SET_MODULE_RONX, which seek to make sure that code is not +In support of this are CONFIG_STRICT_KERNEL_RWX and +CONFIG_STRICT_MODULE_RWX, which seek to make sure that code is not writable, data is not executable, and read-only data is neither writable nor executable. +Most architectures have these options on by default and not user selectable. +For some architectures like arm that wish to have these be selectable, +the architecture Kconfig can select ARCH_OPTIONAL_KERNEL_RWX to enable +a Kconfig prompt. CONFIG_ARCH_OPTIONAL_KERNEL_RWX_DEFAULT determines +the default setting when ARCH_OPTIONAL_KERNEL_RWX is enabled. + #### Function pointers and sensitive variables must not be writable Vast areas of kernel memory contain function pointers that are looked |