Messages in this thread | | | Date | Fri, 25 Nov 2022 17:41:49 +0100 | Subject | Re: [PATCH v3 2/9] LSM: Identify the process attributes for each module | From | Mickaël Salaün <> |
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On 23/11/2022 21:15, Casey Schaufler wrote: > Add an integer member "attrs_used" to the struct lsm_id which > identifies the API related data associated with each security > module. The initial set of features maps to information that > has traditionaly been available in /proc/self/attr. They are > documented in a new userspace-api file. > > Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> > --- > Documentation/userspace-api/index.rst | 1 + > Documentation/userspace-api/lsm.rst | 55 +++++++++++++++++++++++++++ > include/linux/lsm_hooks.h | 2 + > include/uapi/linux/lsm.h | 12 ++++++ > security/apparmor/lsm.c | 1 + > security/selinux/hooks.c | 2 + > security/smack/smack_lsm.c | 1 + > 7 files changed, 74 insertions(+) > create mode 100644 Documentation/userspace-api/lsm.rst > > diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst > index c78da9ce0ec4..6feff0fcd88f 100644 > --- a/Documentation/userspace-api/index.rst > +++ b/Documentation/userspace-api/index.rst > @@ -30,6 +30,7 @@ place where this information is gathered. > sysfs-platform_profile > vduse > futex2 > + lsm > > .. only:: subproject and html > > diff --git a/Documentation/userspace-api/lsm.rst b/Documentation/userspace-api/lsm.rst > new file mode 100644 > index 000000000000..6ddf5506110b > --- /dev/null > +++ b/Documentation/userspace-api/lsm.rst > @@ -0,0 +1,55 @@ > +.. SPDX-License-Identifier: GPL-2.0 > +.. Copyright (C) 2022 Casey Schaufler <casey@schaufler-ca.com> > +.. Copyright (C) 2022 Intel Corporation > + > +===================================== > +Linux Security Modules > +===================================== > + > +:Author: Casey Schaufler > +:Date: November 2022 > + > +Linux security modules (LSM) provide a mechanism to implement > +additional access controls to the Linux security policies. > + > +The various security modules may support any of these attributes: > + > +``LSM_ATTR_CURRENT`` is the current, active security context of the > +process. > +The proc filesystem provides this value in ``/proc/self/attr/current``. > +This is supported by the SELinux, Smack and AppArmor security modules. > +Smack also provides this value in ``/proc/self/attr/smack/current``. > +AppArmor also provides this value in ``/proc/self/attr/apparmor/current``. > + > +``LSM_ATTR_EXEC`` is the security context of the process at the time the > +current image was executed. > +The proc filesystem provides this value in ``/proc/self/attr/exec``. > +This is supported by the SELinux and AppArmor security modules. > +AppArmor also provides this value in ``/proc/self/attr/apparmor/exec``. > + > +``LSM_ATTR_FSCREATE`` is the security context of the process used when > +creating file system objects. > +The proc filesystem provides this value in ``/proc/self/attr/fscreate``. > +This is supported by the SELinux security module. > + > +``LSM_ATTR_KEYCREATE`` is the security context of the process used when > +creating key objects. > +The proc filesystem provides this value in ``/proc/self/attr/keycreate``. > +This is supported by the SELinux security module. > + > +``LSM_ATTR_PREV`` is the security context of the process at the time the > +current security context was set. > +The proc filesystem provides this value in ``/proc/self/attr/prev``. > +This is supported by the SELinux and AppArmor security modules. > +AppArmor also provides this value in ``/proc/self/attr/apparmor/prev``. > + > +``LSM_ATTR_SOCKCREATE`` is the security context of the process used when > +creating socket objects. > +The proc filesystem provides this value in ``/proc/self/attr/sockcreate``. > +This is supported by the SELinux security module. > + > +Additional documentation > +======================== > + > +* Documentation/security/lsm.rst > +* Documentation/security/lsm-development.rst > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h > index d306db1044d1..7e88acc37a29 100644 > --- a/include/linux/lsm_hooks.h > +++ b/include/linux/lsm_hooks.h > @@ -1606,12 +1606,14 @@ struct security_hook_heads { > * struct lsm_id - identify a Linux Security Module. > * @lsm: Name of the LSM. Must be approved by the LSM maintainers. > * @id: LSM ID number from uapi/linux/lsm.h > + * @attrs_used: Which attributes this LSM supports. > * > * Contains the information that identifies the LSM. > */ > struct lsm_id { > const u8 *lsm; > u32 id; > + u64 attrs_used;
I'd prefer this field to be part of the previous patch. This doesn't change much but it is to highlight that the struct lsm_id size should not change unless properly handled by userspace.
> }; > > /* > diff --git a/include/uapi/linux/lsm.h b/include/uapi/linux/lsm.h > index 47791c330cbf..8e9124bf622c 100644 > --- a/include/uapi/linux/lsm.h > +++ b/include/uapi/linux/lsm.h > @@ -29,4 +29,16 @@ > #define LSM_ID_BPF 110 > #define LSM_ID_LANDLOCK 111 > > +/* > + * LSM_ATTR_XXX values identify the /proc/.../attr entry that the > + * context represents. Not all security modules provide all of these > + * values. Some security modules provide none of them. > + */ > +#define LSM_ATTR_CURRENT 0x0001 > +#define LSM_ATTR_EXEC 0x0002 > +#define LSM_ATTR_FSCREATE 0x0004 > +#define LSM_ATTR_KEYCREATE 0x0008 > +#define LSM_ATTR_PREV 0x0010 > +#define LSM_ATTR_SOCKCREATE 0x0020 > + > #endif /* _UAPI_LINUX_LSM_H */ > diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c > index b859b1af6c75..3a6bf4f95d84 100644 > --- a/security/apparmor/lsm.c > +++ b/security/apparmor/lsm.c > @@ -1206,6 +1206,7 @@ struct lsm_blob_sizes apparmor_blob_sizes __lsm_ro_after_init = { > static struct lsm_id apparmor_lsmid __lsm_ro_after_init = { > .lsm = "apparmor", > .id = LSM_ID_APPARMOR, > + .attrs_used = LSM_ATTR_CURRENT | LSM_ATTR_PREV | LSM_ATTR_EXEC, > }; > > static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = { > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index 5fcce36267bd..e831d9c38c54 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -7018,6 +7018,8 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd) > static struct lsm_id selinux_lsmid __lsm_ro_after_init = { > .lsm = "selinux", > .id = LSM_ID_SELINUX, > + .attrs_used = LSM_ATTR_CURRENT | LSM_ATTR_EXEC | LSM_ATTR_FSCREATE | > + LSM_ATTR_KEYCREATE | LSM_ATTR_PREV | LSM_ATTR_SOCKCREATE, > }; > > /* > diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c > index c7ba80e20b8d..c2a05217bde4 100644 > --- a/security/smack/smack_lsm.c > +++ b/security/smack/smack_lsm.c > @@ -4791,6 +4791,7 @@ struct lsm_blob_sizes smack_blob_sizes __lsm_ro_after_init = { > static struct lsm_id smack_lsmid __lsm_ro_after_init = { > .lsm = "smack", > .id = LSM_ID_SMACK, > + .attrs_used = LSM_ATTR_CURRENT, > }; > > static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
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