On 8/8/19 12:30 PM, Paul Moore wrote:
On Thu, Aug 1, 2019 at 10:43 AM Aaron Goidel <acgoide@xxxxxxxxxxxxx> wrote:
From: Nicholas Franck <nhfran2@xxxxxxxxxxxxx>
At present security_capable does not pass any object information
and therefore can neither audit the particular object nor take it
into account. Augment the security_capable interface to support
passing supplementary data. Use this facility initially to convey
the inode for capability checks relevant to inodes. This only
addresses capable_wrt_inode_uidgid calls; other capability checks
relevant to inodes will be addressed in subsequent changes. In the
future, this will be further extended to pass object information for
other capability checks such as the target task for CAP_KILL.
In SELinux this new information is leveraged here to include the inode
in the audit message. In the future, it could also be used to perform
a per inode capability checks.
It would be possible to fold the existing opts argument into this new
supplementary data structure. This was omitted from this change to
minimize changes.
Signed-off-by: Nicholas Franck <nhfran2@xxxxxxxxxxxxx>
Signed-off-by: Aaron Goidel <acgoide@xxxxxxxxxxxxx>
---
v2:
- Changed order of audit prints so optional information comes second
---
include/linux/capability.h | 7 ++++++
include/linux/lsm_audit.h | 5 +++-
include/linux/lsm_hooks.h | 3 ++-
include/linux/security.h | 23 +++++++++++++-----
kernel/capability.c | 33 ++++++++++++++++++--------
kernel/seccomp.c | 2 +-
security/apparmor/capability.c | 8 ++++---
security/apparmor/include/capability.h | 4 +++-
security/apparmor/ipc.c | 2 +-
security/apparmor/lsm.c | 5 ++--
security/apparmor/resource.c | 2 +-
security/commoncap.c | 11 +++++----
security/lsm_audit.c | 21 ++++++++++++++--
security/safesetid/lsm.c | 3 ++-
security/security.c | 5 ++--
security/selinux/hooks.c | 20 +++++++++-------
security/smack/smack_access.c | 2 +-
17 files changed, 110 insertions(+), 46 deletions(-)
You should CC the linux-audit list, I've added them on this mail.
I had hoped to see some thought put into the idea of dynamically
emitting the proper audit records as I mentioned in the previous patch
set, but regardless there are some comments on this code as written
...
diff --git a/security/lsm_audit.c b/security/lsm_audit.c
index 33028c098ef3..18cc7c956b69 100644
--- a/security/lsm_audit.c
+++ b/security/lsm_audit.c
@@ -229,9 +229,26 @@ static void dump_common_audit_data(struct audit_buffer *ab,
case LSM_AUDIT_DATA_IPC:
audit_log_format(ab, " key=%d ", a->u.ipc_id);
break;
- case LSM_AUDIT_DATA_CAP:
- audit_log_format(ab, " capability=%d ", a->u.cap);
+ case LSM_AUDIT_DATA_CAP: {
+ const struct inode *inode;
+
+ audit_log_format(ab, " capability=%d ", a->u.cap_struct.cap);
+ if (a->u.cap_struct.cad) {
+ switch (a->u.cap_struct.cad->type) {
+ case CAP_AUX_DATA_INODE: {
+ inode = a->u.cap_struct.cad->u.inode;
+
+ audit_log_format(ab, " dev=");
+ audit_log_untrustedstring(ab,
+ inode->i_sb->s_id);
+ audit_log_format(ab, " ino=%lu",
+ inode->i_ino);
+ break;
+ }
Since you are declaring "inode" further up, there doesn't appear to be
any need for the CAP_AUX_DATA_INODE braces, please remove them.
The general recommended practice when it comes to "sometimes" fields
in an audit record, is to always record them in the record, but use a
value of "?" when there is nothing relevant to record. For example,
when *not* recording inode information you would do something like the
following:
audit_log_format(ab, " dev=? ino=?");
The issue this brings up is what happens when this is expanded to more
cases? Assuming there will be a case here for logging audit data for
task based capabilities (CAP_AUX_DATA_TASK), what do we want to have
happen if we are recording *neither* inode information nor task
information (say a PID)? If we log something in the inode case, we
presumably don't want to call audit_log_format(ab, " dev=?, pid=?") as
well. (And vice versa for when we log a pid and no inode).
+ }
+ }
break;
+ }
case LSM_AUDIT_DATA_PATH: {
struct inode *inode;
--
Aaron
