[PATCH v10 00/25] LSM: Module stacking for AppArmor
Stephen Smalley
sds at tycho.nsa.gov
Tue Oct 29 14:53:34 UTC 2019
On 10/24/19 4:52 PM, Casey Schaufler wrote:
> This patchset provides the changes required for
> the AppArmor security module to stack safely with any other.
>
> v10: Ask the security modules if the display can be changed.
>
> v9: There is no version 9
>
> v8: Incorporate feedback from v7
> - Minor clean-up in display value management
> - refactor "compound" context creation to use a common
> append_ctx() function.
>
> v7: Incorporate feedback from v6
> - Make setting the display a privileged operation. The
> availability of compound contexts reduces the need for
> setting the display.
>
> v6: Incorporate feedback from v5
> - Add subj_<lsm>= and obj_<lsm>= fields to audit records
> - Add /proc/.../attr/context to get the full context in
> lsmname\0value\0... format as suggested by Simon McVittie
> - Add SO_PEERCONTEXT for getsockopt() to get the full context
> in the same format, also suggested by Simon McVittie.
> - Add /sys/kernel/security/lsm_display_default to provide
> the display default value.
>
> v5: Incorporate feedback from v4
> - Initialize the lsmcontext in security_secid_to_secctx()
> - Clear the lsmcontext in all security_release_secctx() cases
> - Don't use the "display" on strictly internal context
> interfaces.
> - The SELinux binder hooks check for cases where the context
> "display" isn't compatible with SELinux.
>
> v4: Incorporate feedback from v3
> - Mark new lsm_<blob>_alloc functions static
> - Replace the lsm and slot fields of the security_hook_list
> with a pointer to a LSM allocated lsm_id structure. The
> LSM identifies if it needs a slot explicitly. Use the
> lsm_id rather than make security_add_hooks return the
> slot value.
> - Validate slot values used in security.c
> - Reworked the "display" process attribute handling so that
> it works right and doesn't use goofy list processing.
> - fix display value check in dentry_init_security
> - Replace audit_log of secids with '?' instead of deleting
> the audit log
>
> v3: Incorporate feedback from v2
> - Make lsmblob parameter and variable names more
> meaningful, changing "le" and "l" to "blob".
> - Improve consistency of constant naming.
> - Do more sanity checking during LSM initialization.
> - Be a bit clearer about what is temporary scaffolding.
> - Rather than clutter security_getpeersec_dgram with
> otherwise unnecessary checks remove the apparmor
> stub, which does nothing useful.
>
> Patche 0001 moves management of the sock security blob from the individual
> modules to the infrastructure.
>
> Patches 0002-0012 replace system use of a "secid" with
> a structure "lsmblob" containing information from the
> security modules to be held and reused later. At this
> point lsmblob contains an array of u32 secids, one "slot"
> for each of the security modules compiled into the
> kernel that used secids. A "slot" is allocated when
> a security module requests one.
> The infrastructure is changed to use the slot number
> to pass the correct secid to or from the security module
> hooks.
>
> It is important that the lsmblob be a fixed size entity
> that does not have to be allocated. Several of the places
> where it is used would have performance and/or locking
> issues with dynamic allocation.
>
> Patch 0013 provides a mechanism for a process to
> identify which security module's hooks should be used
> when displaying or converting a security context string.
> A new interface /proc/.../attr/display contains the name
> of the security module to show. Reading from this file
> will present the name of the module, while writing to
> it will set the value. Only names of active security
> modules are accepted. Internally, the name is translated
> to the appropriate "slot" number for the module which
> is then stored in the task security blob. Setting the
> display requires that all modules using the /proc interfaces
> allow the transition.
>
> Patch 0014 Starts the process of changing how a security
> context is represented. Since it is possible for a
> security context to have been generated by more than one
> security module it is now necessary to note which module
> created a security context so that the correct "release"
> hook can be called. There are several places where the
> module that created a security context cannot be inferred.
>
> This is achieved by introducing a "lsmcontext" structure
> which contains the context string, its length and the
> "slot" number of the security module that created it.
> The security_release_secctx() interface is changed,
> replacing the (string,len) pointer pair with a lsmcontext
> pointer.
>
> Patches 0015-0017 convert the security interfaces from
> (string,len) pointer pairs to a lsmcontext pointer.
> The slot number identifying the creating module is
> added by the infrastructure. Where the security context
> is stored for extended periods the data type is changed.
>
> The Netlabel code is converted to save lsmblob structures
> instead of secids in Patches 0018-0019.
>
> Patch 0020 adds checks to the binder hooks which verify
> that if both ends of a transaction use the same "display".
>
> Patches 0021-0022 add addition data to the audit records
> to identify the LSM specific data for all active modules.
>
> Patches 0023-0024 add new interfaces for getting the
> compound security contexts.
>
> Finally, with all interference on the AppArmor hooks
> removed, Patch 0025 removes the exclusive bit from
> AppArmor. An unnecessary stub hook was also removed.
>
> The Ubuntu project is using an earlier version of
> this patchset in their distribution to enable stacking
> for containers.
>
> Performance measurements to date have the change
> within the "noise". The sockperf and dbench results
> are on the order of 0.2% to 0.8% difference, with
> better performance being as common as worse. The
> benchmarks were run with AppArmor and Smack on Ubuntu.
>
> https://github.com/cschaufler/lsm-stacking.git#stack-5.2-v10-apparmor
Can you re-base on something more recent than v5.1-rc2 (that's the base
for that branch currently)?
At present it won't even boot for me on modern Fedora. Two key missing
commits are:
e33c1b9923775d17ad246946fe67fcb9be288677 ("apparmor: Restore Y/N in /sys
for apparmor's "enabled") - without this, dbus falls over (or at least
dbus-broker in Fedora)
169ce0c081cd85f78388bb6c1638c1ad7b81bde7 ("selinux: fix residual uses of
current_security() for the SELinux blob") - without this, selinux ends
up dereferencing something other than its own security blob after these
patches
>
> Signed-off-by: Casey Schaufler <casey at schaufler-ca.com>
> ---
> arch/alpha/include/uapi/asm/socket.h | 1 +
> arch/mips/include/uapi/asm/socket.h | 1 +
> arch/parisc/include/uapi/asm/socket.h | 1 +
> arch/sparc/include/uapi/asm/socket.h | 1 +
> drivers/android/binder.c | 24 +-
> fs/kernfs/dir.c | 5 +-
> fs/kernfs/inode.c | 35 +-
> fs/kernfs/kernfs-internal.h | 3 +-
> fs/nfs/nfs4proc.c | 22 +-
> fs/nfsd/nfs4xdr.c | 20 +-
> fs/proc/base.c | 2 +
> include/linux/audit.h | 1 +
> include/linux/cred.h | 3 +-
> include/linux/lsm_hooks.h | 37 +-
> include/linux/security.h | 175 ++++++++--
> include/net/af_unix.h | 2 +-
> include/net/netlabel.h | 8 +-
> include/net/scm.h | 15 +-
> include/uapi/asm-generic/socket.h | 1 +
> kernel/audit.c | 70 +++-
> kernel/audit.h | 9 +-
> kernel/audit_fsnotify.c | 1 +
> kernel/auditfilter.c | 10 +-
> kernel/auditsc.c | 129 ++++---
> kernel/cred.c | 12 +-
> net/core/sock.c | 7 +-
> net/ipv4/cipso_ipv4.c | 6 +-
> net/ipv4/ip_sockglue.c | 12 +-
> net/netfilter/nf_conntrack_netlink.c | 20 +-
> net/netfilter/nf_conntrack_standalone.c | 11 +-
> net/netfilter/nfnetlink_queue.c | 26 +-
> net/netfilter/nft_meta.c | 13 +-
> net/netfilter/xt_SECMARK.c | 5 +-
> net/netlabel/netlabel_kapi.c | 6 +-
> net/netlabel/netlabel_unlabeled.c | 97 +++---
> net/netlabel/netlabel_unlabeled.h | 2 +-
> net/netlabel/netlabel_user.c | 13 +-
> net/netlabel/netlabel_user.h | 6 +-
> net/unix/af_unix.c | 6 +-
> net/xfrm/xfrm_policy.c | 2 +
> net/xfrm/xfrm_state.c | 2 +
> security/apparmor/include/apparmor.h | 3 +-
> security/apparmor/include/net.h | 6 +-
> security/apparmor/lsm.c | 121 ++++---
> security/commoncap.c | 7 +-
> security/integrity/ima/ima.h | 14 +-
> security/integrity/ima/ima_api.c | 10 +-
> security/integrity/ima/ima_appraise.c | 6 +-
> security/integrity/ima/ima_main.c | 36 +-
> security/integrity/ima/ima_policy.c | 19 +-
> security/integrity/integrity_audit.c | 1 +
> security/loadpin/loadpin.c | 8 +-
> security/safesetid/lsm.c | 8 +-
> security/security.c | 586 +++++++++++++++++++++++++++++---
> security/selinux/hooks.c | 109 +++---
> security/selinux/include/classmap.h | 2 +-
> security/selinux/include/objsec.h | 5 +
> security/selinux/include/security.h | 1 +
> security/selinux/netlabel.c | 25 +-
> security/selinux/ss/services.c | 4 +-
> security/smack/smack.h | 6 +
> security/smack/smack_lsm.c | 124 ++++---
> security/smack/smack_netfilter.c | 8 +-
> security/smack/smackfs.c | 10 +-
> security/tomoyo/tomoyo.c | 8 +-
> security/yama/yama_lsm.c | 7 +-
> 66 files changed, 1376 insertions(+), 580 deletions(-)
>
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