---
v4:
- Changed retval debugfs file type - now it keeps a signed integer.
- Made CONFIG_FAIL_LSM_HOOKS depend on CONFIG_SECURITY.
v2:
- Renamed should_fail_lsm_hook() to lsm_hooks_inject_fail().
---
 lib/Kconfig.debug   |  6 ++++
 security/security.c | 69 +++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 72 insertions(+), 3 deletions(-)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 6140413174be..5f4399816019 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug

@@ -1813,6 +1813,12 @@ config FAIL_MAKE_REQUEST
        help
          Provide fault-injection capability for disk IO.

+config FAIL_LSM_HOOKS
+       bool "Fault-injection capability for LSM hooks"
+       depends on FAULT_INJECTION && SECURITY
+       help
+         Provide fault-injection capability for LSM hooks.
+
 config FAIL_IO_TIMEOUT
        bool "Fault-injection capability for faking disk interrupts"
        depends on FAULT_INJECTION && BLOCK

diff --git a/security/security.c b/security/security.c
index 69ff6e2e2cd4..be3a3c7c6d6a 100644
--- a/security/security.c
+++ b/security/security.c

@@ -28,6 +28,7 @@
 #include <linux/backing-dev.h>
 #include <linux/string.h>
 #include <linux/msg.h>
+#include <linux/fault-inject.h>
 #include <net/flow.h>

 #define MAX_LSM_EVM_XATTR      2

@@ -669,6 +670,67 @@ static void __init lsm_early_task(struct task_struct *task)
                panic("%s: Early task alloc failed.\n", __func__);
 }

+
+#ifdef CONFIG_FAIL_LSM_HOOKS
+
+static struct {
+       struct fault_attr attr;
+       int retval;
+} fail_lsm_hooks = {
+       .attr = FAULT_ATTR_INITIALIZER,
+       .retval = -EACCES
+};
+
+static int __init setup_fail_lsm_hooks(char *str)
+{
+       return setup_fault_attr(&fail_lsm_hooks.attr, str);
+}
+__setup("fail_lsm_hooks=", setup_fail_lsm_hooks);
+
+static int lsm_hooks_inject_fail(void)
+{
+       return should_fail(&fail_lsm_hooks.attr, 1) ? fail_lsm_hooks.retval : 0;
+}
+
+#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
+
+static int fail_lsm_retval_set(void *data, u64 val)
+{
+       fail_lsm_hooks.retval = (int)val;
+       return 0;
+}
+
+static int fail_lsm_retval_get(void *data, u64 *val)
+{
+       *val = (u64)fail_lsm_hooks.retval;
+       return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(fail_lsm_retval_ops, fail_lsm_retval_get,
+                                                fail_lsm_retval_set, "%lld\n");
+
+static int __init fail_lsm_hooks_debugfs(void)
+{
+       umode_t mode = S_IFREG | 0600;
+       struct dentry *dir;
+
+       dir = fault_create_debugfs_attr("fail_lsm_hooks", NULL,
+                                       &fail_lsm_hooks.attr);
+       debugfs_create_file("retval", mode, dir, NULL,
+                                               &fail_lsm_retval_ops);
+       return 0;
+}
+
+late_initcall(fail_lsm_hooks_debugfs);
+
+#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
+
+#else
+
+static inline int lsm_hooks_inject_fail(void) { return 0; }
+
+#endif /* CONFIG_FAIL_LSM_HOOKS */
+
 /*
  * The default value of the LSM hook is defined in linux/lsm_hook_defs.h and
  * can be accessed with:

@@ -707,16 +769,17 @@ static void __init lsm_early_task(struct task_struct *task)
        } while (0)

 #define call_int_hook(FUNC, IRC, ...) ({                       \
-       int RC = IRC;                                           \
-       do {                                                    \
+       int RC = lsm_hooks_inject_fail();                       \
+       if (RC == 0) {                                                          \
                struct security_hook_list *P;                   \
+               RC = IRC;                                                               \
                                                                \
                hlist_for_each_entry(P, &security_hook_heads.FUNC, list) { \
                        RC = P->hook.FUNC(__VA_ARGS__);         \
                        if (RC != 0)                            \
                                break;                          \
                }                                               \
-       } while (0);                                            \
+       }                                                       \
        RC;                                                     \
 })

--

2.29.2.222.g5d2a92d10f8-goog