[PATCH v15 08/23] LSM: Use lsmblob in security_ipc_getsecid

Casey Schaufler
2020-02-22T00:05:10Z

There may be more than one LSM that provides IPC data
for auditing. Change security_ipc_getsecid() to fill in
a lsmblob structure instead of the u32 secid. The
audit data structure containing the secid will be updated
later, so there is a bit of scaffolding here.

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
include/linux/security.h | 7 ++++---
kernel/auditsc.c | 5 ++++-
security/security.c | 12 +++++++++---
3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index fdcba6e8d242..3ceea6c51bed 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -468,7 +468,7 @@ int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5);
void security_task_to_inode(struct task_struct *p, struct inode *inode);
int security_ipc_permission(struct kern_ipc_perm *ipcp, short flag);
-void security_ipc_getsecid(struct kern_ipc_perm *ipcp, u32 *secid);
+void security_ipc_getsecid(struct kern_ipc_perm *ipcp, struct lsmblob *blob);
int security_msg_msg_alloc(struct msg_msg *msg);
void security_msg_msg_free(struct msg_msg *msg);
int security_msg_queue_alloc(struct kern_ipc_perm *msq);
@@ -1176,9 +1176,10 @@ static inline int security_ipc_permission(struct kern_ipc_perm *ipcp,
return 0;
}

-static inline void security_ipc_getsecid(struct kern_ipc_perm *ipcp, u32 *secid)
+static inline void security_ipc_getsecid(struct kern_ipc_perm *ipcp,
+ struct lsmblob *blob)
{
- *secid = 0;
+ lsmblob_init(blob, 0);
}

static inline int security_msg_msg_alloc(struct msg_msg *msg)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index d6723c225c7e..032cdb603ac0 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2285,11 +2285,14 @@ void __audit_mq_getsetattr(mqd_t mqdes, struct mq_attr *mqstat)
void __audit_ipc_obj(struct kern_ipc_perm *ipcp)
{
struct audit_context *context = audit_context();
+ struct lsmblob blob;
context->ipc.uid = ipcp->uid;
context->ipc.gid = ipcp->gid;
context->ipc.mode = ipcp->mode;
context->ipc.has_perm = 0;
- security_ipc_getsecid(ipcp, &context->ipc.osid);
+ security_ipc_getsecid(ipcp, &blob);
+ /* scaffolding on the [0] - change "osid" to a lsmblob */
+ context->ipc.osid = blob.secid[0];
context->type = AUDIT_IPC;
}

diff --git a/security/security.c b/security/security.c
index dae86629a2f6..9d67db68f6f2 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1815,10 +1815,16 @@ int security_ipc_permission(struct kern_ipc_perm *ipcp, short flag)
return call_int_hook(ipc_permission, 0, ipcp, flag);
}

-void security_ipc_getsecid(struct kern_ipc_perm *ipcp, u32 *secid)
+void security_ipc_getsecid(struct kern_ipc_perm *ipcp, struct lsmblob *blob)
{
- *secid = 0;
- call_void_hook(ipc_getsecid, ipcp, secid);
+ struct security_hook_list *hp;
+
+ lsmblob_init(blob, 0);
+ hlist_for_each_entry(hp, &security_hook_heads.ipc_getsecid, list) {
+ if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
+ continue;
+ hp->hook.ipc_getsecid(ipcp, &blob->secid[hp->lsmid->slot]);
+ }
}

int security_msg_msg_alloc(struct msg_msg *msg)