提交 867c2026 编写于 作者: M Mimi Zohar 提交者: Linus Torvalds

ima: fix add LSM rule bug

If security_filter_rule_init() doesn't return a rule, then not everything
is as fine as the return code implies.

This bug only occurs when the LSM (eg. SELinux) is disabled at runtime.

Adding an empty LSM rule causes ima_match_rules() to always succeed,
ignoring any remaining rules.

 default IMA TCB policy:
  # PROC_SUPER_MAGIC
  dont_measure fsmagic=0x9fa0
  # SYSFS_MAGIC
  dont_measure fsmagic=0x62656572
  # DEBUGFS_MAGIC
  dont_measure fsmagic=0x64626720
  # TMPFS_MAGIC
  dont_measure fsmagic=0x01021994
  # SECURITYFS_MAGIC
  dont_measure fsmagic=0x73636673

  < LSM specific rule >
  dont_measure obj_type=var_log_t

  measure func=BPRM_CHECK
  measure func=FILE_MMAP mask=MAY_EXEC
  measure func=FILE_CHECK mask=MAY_READ uid=0

Thus without the patch, with the boot parameters 'tcb selinux=0', adding
the above 'dont_measure obj_type=var_log_t' rule to the default IMA TCB
measurement policy, would result in nothing being measured.  The patch
prevents the default TCB policy from being replaced.
Signed-off-by: NMimi Zohar <zohar@us.ibm.com>
Cc: James Morris <jmorris@namei.org>
Acked-by: NSerge Hallyn <serge.hallyn@canonical.com>
Cc: David Safford <safford@watson.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 03ed6a3a
......@@ -253,6 +253,8 @@ static int ima_lsm_rule_init(struct ima_measure_rule_entry *entry,
result = security_filter_rule_init(entry->lsm[lsm_rule].type,
Audit_equal, args,
&entry->lsm[lsm_rule].rule);
if (!entry->lsm[lsm_rule].rule)
return -EINVAL;
return result;
}
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册