security: report the module name to security_module_request

For SELinux to do better filtering in userspace we send the name of the
module along with the AVC denial when a program is denied module_request.

Example output:

type=SYSCALL msg=audit(11/03/2009 10:59:43.510:9) : arch=x86_64 syscall=write success=yes exit=2 a0=3 a1=7fc28c0d56c0 a2=2 a3=7fffca0d7440 items=0 ppid=1727 pid=1729 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=rpc.nfsd exe=/usr/sbin/rpc.nfsd subj=system_u:system_r:nfsd_t:s0 key=(null)
type=AVC msg=audit(11/03/2009 10:59:43.510:9) : avc:  denied  { module_request } for  pid=1729 comm=rpc.nfsd kmod="net-pf-10" scontext=system_u:system_r:nfsd_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=system

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

7 files changed, 36 insertions, 20 deletions

diff --git a/include/linux/lsm_audit.h b/include/linux/lsm_audit.h
index 190c37854870..f78f83d7663f 100644
--- a/include/linux/lsm_audit.h
+++ b/include/linux/lsm_audit.h
@@ -26,14 +26,15 @@
 
 /* Auxiliary data to use in generating the audit record. */
 struct common_audit_data {
-        char    type;
-#define LSM_AUDIT_DATA_FS      1
-#define LSM_AUDIT_DATA_NET     2
-#define LSM_AUDIT_DATA_CAP     3
-#define LSM_AUDIT_DATA_IPC     4
-#define LSM_AUDIT_DATA_TASK    5
-#define LSM_AUDIT_DATA_KEY     6
-#define LSM_AUDIT_NO_AUDIT     7
+        char type;
+#define LSM_AUDIT_DATA_FS       1
+#define LSM_AUDIT_DATA_NET      2
+#define LSM_AUDIT_DATA_CAP      3
+#define LSM_AUDIT_DATA_IPC      4
+#define LSM_AUDIT_DATA_TASK     5
+#define LSM_AUDIT_DATA_KEY      6
+#define LSM_AUDIT_NO_AUDIT      7
+#define LSM_AUDIT_DATA_KMOD     8
         struct task_struct *tsk;
         union   {
                 struct {
@@ -66,6 +67,7 @@ struct common_audit_data {
                         char *key_desc;
                 } key_struct;
 #endif
+                char *kmod_name;
         } u;
         /* this union contains LSM specific data */
         union {
diff --git a/include/linux/security.h b/include/linux/security.h
index ed0faea60b82..466cbadbd1ef 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -706,6 +706,7 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  * @kernel_module_request:
  *      Ability to trigger the kernel to automatically upcall to userspace for
  *      userspace to load a kernel module with the given name.
+ *      @kmod_name name of the module requested by the kernel
  *      Return 0 if successful.
  * @task_setuid:
  *      Check permission before setting one or more of the user identity
@@ -1577,7 +1578,7 @@ struct security_operations {
         void (*cred_transfer)(struct cred *new, const struct cred *old);
         int (*kernel_act_as)(struct cred *new, u32 secid);
         int (*kernel_create_files_as)(struct cred *new, struct inode *inode);
-        int (*kernel_module_request)(void);
+        int (*kernel_module_request)(char *kmod_name);
         int (*task_setuid) (uid_t id0, uid_t id1, uid_t id2, int flags);
         int (*task_fix_setuid) (struct cred *new, const struct cred *old,
                                 int flags);
@@ -1842,7 +1843,7 @@ void security_commit_creds(struct cred *new, const struct cred *old);
 void security_transfer_creds(struct cred *new, const struct cred *old);
 int security_kernel_act_as(struct cred *new, u32 secid);
 int security_kernel_create_files_as(struct cred *new, struct inode *inode);
-int security_kernel_module_request(void);
+int security_kernel_module_request(char *kmod_name);
 int security_task_setuid(uid_t id0, uid_t id1, uid_t id2, int flags);
 int security_task_fix_setuid(struct cred *new, const struct cred *old,
                              int flags);
@@ -2407,7 +2408,7 @@ static inline int security_kernel_create_files_as(struct cred *cred,
         return 0;
 }
 
-static inline int security_kernel_module_request(void)
+static inline int security_kernel_module_request(char *kmod_name)
 {
         return 0;
 }
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 9fcb53a11f87..25b103190364 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -80,16 +80,16 @@ int __request_module(bool wait, const char *fmt, ...)
 #define MAX_KMOD_CONCURRENT 50  /* Completely arbitrary value - KAO */
         static int kmod_loop_msg;
 
-        ret = security_kernel_module_request();
-        if (ret)
-                return ret;
-
         va_start(args, fmt);
         ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
         va_end(args);
         if (ret >= MODULE_NAME_LEN)
                 return -ENAMETOOLONG;
 
+        ret = security_kernel_module_request(module_name);
+        if (ret)
+                return ret;
+
         /* If modprobe needs a service that is in a module, we get a recursive
          * loop.  Limit the number of running kmod threads to max_threads/2 or
          * MAX_KMOD_CONCURRENT, whichever is the smaller.  A cleaner method
diff --git a/security/capability.c b/security/capability.c
index 4f3ab476937f..5c700e1a4fd3 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -421,7 +421,7 @@ static int cap_kernel_create_files_as(struct cred *new, struct inode *inode)
         return 0;
 }
 
-static int cap_kernel_module_request(void)
+static int cap_kernel_module_request(char *kmod_name)
 {
         return 0;
 }
diff --git a/security/lsm_audit.c b/security/lsm_audit.c
index 3bb90b6f1dd3..51bd0fd9c9f0 100644
--- a/security/lsm_audit.c
+++ b/security/lsm_audit.c
@@ -354,6 +354,10 @@ static void dump_common_audit_data(struct audit_buffer *ab,
                 }
                 break;
 #endif
+        case LSM_AUDIT_DATA_KMOD:
+                audit_log_format(ab, " kmod=");
+                audit_log_untrustedstring(ab, a->u.kmod_name);
+                break;
         } /* switch (a->type) */
 }
 
diff --git a/security/security.c b/security/security.c
index aad71b2ca195..24e060be9fa5 100644
--- a/security/security.c
+++ b/security/security.c
@@ -764,9 +764,9 @@ int security_kernel_create_files_as(struct cred *new, struct inode *inode)
         return security_ops->kernel_create_files_as(new, inode);
 }
 
-int security_kernel_module_request(void)
+int security_kernel_module_request(char *kmod_name)
 {
-        return security_ops->kernel_module_request();
+        return security_ops->kernel_module_request(kmod_name);
 }
 
 int security_task_setuid(uid_t id0, uid_t id1, uid_t id2, int flags)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index a29d6612a328..c96d63ec4753 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3337,9 +3337,18 @@ static int selinux_kernel_create_files_as(struct cred *new, struct inode *inode)
         return 0;
 }
 
-static int selinux_kernel_module_request(void)
+static int selinux_kernel_module_request(char *kmod_name)
 {
-        return task_has_system(current, SYSTEM__MODULE_REQUEST);
+        u32 sid;
+        struct common_audit_data ad;
+
+        sid = task_sid(current);
+
+        COMMON_AUDIT_DATA_INIT(&ad, KMOD);
+        ad.u.kmod_name = kmod_name;
+
+        return avc_has_perm(sid, SECINITSID_KERNEL, SECCLASS_SYSTEM,
+                            SYSTEM__MODULE_REQUEST, &ad);
 }
 
 static int selinux_task_setpgid(struct task_struct *p, pid_t pgid)