Commit c037bd61 authored Aug 21, 2018 by John Johansen

apparmor: remove no-op permission check in policy_unpack



The patch 736ec752: "AppArmor: policy routines for loading and
unpacking policy" from Jul 29, 2010, leads to the following static
checker warning:

    security/apparmor/policy_unpack.c:410 verify_accept()
    warn: bitwise AND condition is false here

    security/apparmor/policy_unpack.c:413 verify_accept()
    warn: bitwise AND condition is false here

security/apparmor/policy_unpack.c
   392  #define DFA_VALID_PERM_MASK             0xffffffff
   393  #define DFA_VALID_PERM2_MASK            0xffffffff
   394
   395  /**
   396   * verify_accept - verify the accept tables of a dfa
   397   * @dfa: dfa to verify accept tables of (NOT NULL)
   398   * @flags: flags governing dfa
   399   *
   400   * Returns: 1 if valid accept tables else 0 if error
   401   */
   402  static bool verify_accept(struct aa_dfa *dfa, int flags)
   403  {
   404          int i;
   405
   406          /* verify accept permissions */
   407          for (i = 0; i < dfa->tables[YYTD_ID_ACCEPT]->td_lolen; i++) {
   408                  int mode = ACCEPT_TABLE(dfa)[i];
   409
   410                  if (mode & ~DFA_VALID_PERM_MASK)
   411                          return 0;
   412
   413                  if (ACCEPT_TABLE2(dfa)[i] & ~DFA_VALID_PERM2_MASK)
   414                          return 0;

fixes: 736ec752 ("AppArmor: policy routines for loading and unpacking policy")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

parent 0a6b2923

security/apparmor/policy_unpack.c

+0 −32

Original line number	Diff line number	Diff line
		@@ -389,32 +389,6 @@ static int unpack_strdup(struct aa_ext e, char string, const char name)
		return res;
		}

		#define DFA_VALID_PERM_MASK 0xffffffff
		#define DFA_VALID_PERM2_MASK 0xffffffff

		/**
		* verify_accept - verify the accept tables of a dfa
		* @dfa: dfa to verify accept tables of (NOT NULL)
		* @flags: flags governing dfa
		*
		* Returns: 1 if valid accept tables else 0 if error
		*/
		static bool verify_accept(struct aa_dfa *dfa, int flags)
		{
		int i;

		/* verify accept permissions */
		for (i = 0; i < dfa->tables[YYTD_ID_ACCEPT]->td_lolen; i++) {
		int mode = ACCEPT_TABLE(dfa)[i];

		if (mode & ~DFA_VALID_PERM_MASK)
		return 0;

		if (ACCEPT_TABLE2(dfa)[i] & ~DFA_VALID_PERM2_MASK)
		return 0;
		}
		return 1;
		}

		/**
		* unpack_dfa - unpack a file rule dfa
		@@ -445,15 +419,9 @@ static struct aa_dfa unpack_dfa(struct aa_ext e)
		if (IS_ERR(dfa))
		return dfa;

		if (!verify_accept(dfa, flags))
		goto fail;
		}

		return dfa;

		fail:
		aa_put_dfa(dfa);
		return ERR_PTR(-EPROTO);
		}

		/**