On Tue, Dec 17, 2019 at 02:01:19PM -0800, Casey Schaufler wrote:

On 12/17/2019 9:34 AM, Stephen Smalley wrote:

quoted

On 12/16/19 5:35 PM, Casey Schaufler wrote:

quoted

Change the secid parameter of security_audit_rule_match
to a lsmblob structure pointer. Pass the entry from the
lsmblob structure for the approprite slot to the LSM hook.

Change the users of security_audit_rule_match to use the
lsmblob instead of a u32. In some cases this requires a
temporary conversion using lsmblob_init() that will go
away when other interfaces get converted.

Reviewed-by: Kees Cook <redacted>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
  include/linux/security.h            |  7 ++++---
  kernel/auditfilter.c                |  7 +++++--
  kernel/auditsc.c                    | 14 ++++++++++----
  security/integrity/ima/ima.h        |  4 ++--
  security/integrity/ima/ima_policy.c |  7 +++++--
  security/security.c                 | 18 +++++++++++++++---
  6 files changed, 41 insertions(+), 16 deletions(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index b74dc70088ca..9c6dbe248eaf 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h

@@ -1837,7 +1837,8 @@ static inline int security_key_getsecurity(struct key *key, char **_buffer)

  #ifdef CONFIG_SECURITY
  int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule);
  int security_audit_rule_known(struct audit_krule *krule);
-int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule);
+int security_audit_rule_match(struct lsmblob *blob, u32 field, u32 op,
+                  void *lsmrule);
  void security_audit_rule_free(void *lsmrule);
    #else

@@ -1853,8 +1854,8 @@ static inline int security_audit_rule_known(struct audit_krule *krule)

      return 0;
  }
  -static inline int security_audit_rule_match(u32 secid, u32 field, u32 op,
-                        void *lsmrule)
+static inline int security_audit_rule_match(struct lsmblob *blob, u32 field,
+                        u32 op, void *lsmrule)
  {
      return 0;
  }

diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index b0126e9c0743..356db1dd276c 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c

@@ -1325,6 +1325,7 @@ int audit_filter(int msgtype, unsigned int listtype)

              struct audit_field *f = &e->rule.fields[i];
              pid_t pid;
              u32 sid;
+            struct lsmblob blob;
                switch (f->type) {
              case AUDIT_PID:

@@ -1355,8 +1356,10 @@ int audit_filter(int msgtype, unsigned int listtype)

              case AUDIT_SUBJ_CLR:
                  if (f->lsm_rule) {
                      security_task_getsecid(current, &sid);
-                    result = security_audit_rule_match(sid,
-                           f->type, f->op, f->lsm_rule);
+                    lsmblob_init(&blob, sid);
+                    result = security_audit_rule_match(
+                            &blob, f->type,
+                            f->op, f->lsm_rule);
                  }
                  break;
              case AUDIT_EXE:

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 4effe01ebbe2..7566e5b1c419 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c

@@ -445,6 +445,7 @@ static int audit_filter_rules(struct task_struct *tsk,

      const struct cred *cred;
      int i, need_sid = 1;
      u32 sid;
+    struct lsmblob blob;
      unsigned int sessionid;
        cred = rcu_dereference_check(tsk->cred, tsk == current || task_creation);

@@ -643,7 +644,9 @@ static int audit_filter_rules(struct task_struct *tsk,

                      security_task_getsecid(tsk, &sid);
                      need_sid = 0;
                  }
-                result = security_audit_rule_match(sid, f->type,
+                lsmblob_init(&blob, sid);
+                result = security_audit_rule_match(&blob,
+                                   f->type,
                                     f->op,
                                     f->lsm_rule);
              }

@@ -658,15 +661,17 @@ static int audit_filter_rules(struct task_struct *tsk,

              if (f->lsm_rule) {
                  /* Find files that match */
                  if (name) {
+                    lsmblob_init(&blob, name->osid);
                      result = security_audit_rule_match(
-                                name->osid,
+                                &blob,
                                  f->type,
                                  f->op,
                                  f->lsm_rule);
                  } else if (ctx) {
                      list_for_each_entry(n, &ctx->names_list, list) {
+                        lsmblob_init(&blob, n->osid);
                          if (security_audit_rule_match(
-                                n->osid,
+                                &blob,
                                  f->type,
                                  f->op,
                                  f->lsm_rule)) {

@@ -678,7 +683,8 @@ static int audit_filter_rules(struct task_struct *tsk,

                  /* Find ipc objects that match */
                  if (!ctx || ctx->type != AUDIT_IPC)
                      break;
-                if (security_audit_rule_match(ctx->ipc.osid,
+                lsmblob_init(&blob, ctx->ipc.osid);
+                if (security_audit_rule_match(&blob,
                                    f->type, f->op,
                                    f->lsm_rule))
                      ++result;

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index df4ca482fb53..d95b0ece7434 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h

@@ -381,8 +381,8 @@ static inline int security_filter_rule_init(u32 field, u32 op, char *rulestr,

      return -EINVAL;
  }
  -static inline int security_filter_rule_match(u32 secid, u32 field, u32 op,
-                         void *lsmrule)
+static inline int security_filter_rule_match(struct lsmblob *blob, u32 field,
+                         u32 op, void *lsmrule)
  {
      return -EINVAL;
  }

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index f19a895ad7cd..193ddd55420b 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c

@@ -414,6 +414,7 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,

      for (i = 0; i < MAX_LSM_RULES; i++) {
          int rc = 0;
          u32 osid;
+        struct lsmblob blob;
            if (!rule->lsm[i].rule)
              continue;

@@ -423,7 +424,8 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,

          case LSM_OBJ_ROLE:
          case LSM_OBJ_TYPE:
              security_inode_getsecid(inode, &osid);
-            rc = security_filter_rule_match(osid,
+            lsmblob_init(&blob, osid);
+            rc = security_filter_rule_match(&blob,
                              rule->lsm[i].type,
                              Audit_equal,
                              rule->lsm[i].rule);

@@ -431,7 +433,8 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,

          case LSM_SUBJ_USER:
          case LSM_SUBJ_ROLE:
          case LSM_SUBJ_TYPE:
-            rc = security_filter_rule_match(secid,
+            lsmblob_init(&blob, secid);
+            rc = security_filter_rule_match(&blob,
                              rule->lsm[i].type,
                              Audit_equal,
                              rule->lsm[i].rule);

diff --git a/security/security.c b/security/security.c
index a89634af639a..bfea9739c084 100644
--- a/security/security.c
+++ b/security/security.c

@@ -439,7 +439,7 @@ static int lsm_append(const char *new, char **result)

  /*
   * Current index to use while initializing the lsmblob secid list.
   */
-static int lsm_slot __initdata;
+static int lsm_slot __lsm_ro_after_init;
    /**
   * security_add_hooks - Add a modules hooks to the hook lists.

@@ -2412,9 +2412,21 @@ void security_audit_rule_free(void *lsmrule)

      call_void_hook(audit_rule_free, lsmrule);
  }
  -int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule)
+int security_audit_rule_match(struct lsmblob *blob, u32 field, u32 op,
+                  void *lsmrule)
  {
-    return call_int_hook(audit_rule_match, 0, secid, field, op, lsmrule);
+    struct security_hook_list *hp;
+    int rc;
+
+    hlist_for_each_entry(hp, &security_hook_heads.audit_rule_match, list) {
+        if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
+            continue;

Do you think we really need to retain these WARN_ON()s?

Kees was especially keen on having the WARN_ON().
I'd be fine with removing it.

It should really really never happen, so I like the WARN_ON staying.

-Kees

quoted

  If not, then you could dispense with it now and leave lsm_slot as __initdata?  Otherwise,
Acked-by: Stephen Smalley <redacted>

quoted

+        rc = hp->hook.audit_rule_match(blob->secid[hp->lsmid->slot],
+                           field, op, lsmrule);
+        if (rc != 0)
+            return rc;
+    }
+    return 0;
  }
  #endif /* CONFIG_AUDIT */
 

-- 
Kees Cook