audit: use current whenever possible
authorPaul Moore <paul@paul-moore.com>
Mon, 26 Nov 2018 23:40:07 +0000 (18:40 -0500)
committerPaul Moore <paul@paul-moore.com>
Mon, 26 Nov 2018 23:41:21 +0000 (18:41 -0500)
There are many places, notably audit_log_task_info() and
audit_log_exit(), that take task_struct pointers but in reality they
are always working on the current task.  This patch eliminates the
task_struct arguments and uses current directly which allows a number
of cleanups as well.

Acked-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
drivers/tty/tty_audit.c
include/linux/audit.h
kernel/audit.c
kernel/audit.h
kernel/auditsc.c
security/integrity/ima/ima_api.c

index 50f567b6a66ee4daab87aa5ab347019c592ca274..28f87fd6a28e0ba3aa315b7c0ab0265bcbae7064 100644 (file)
@@ -61,20 +61,19 @@ static void tty_audit_log(const char *description, dev_t dev,
                          unsigned char *data, size_t size)
 {
        struct audit_buffer *ab;
-       struct task_struct *tsk = current;
-       pid_t pid = task_pid_nr(tsk);
-       uid_t uid = from_kuid(&init_user_ns, task_uid(tsk));
-       uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(tsk));
-       unsigned int sessionid = audit_get_sessionid(tsk);
+       pid_t pid = task_pid_nr(current);
+       uid_t uid = from_kuid(&init_user_ns, task_uid(current));
+       uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(current));
+       unsigned int sessionid = audit_get_sessionid(current);
 
        ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
        if (ab) {
-               char name[sizeof(tsk->comm)];
+               char name[sizeof(current->comm)];
 
                audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d"
                                 " minor=%d comm=", description, pid, uid,
                                 loginuid, sessionid, MAJOR(dev), MINOR(dev));
-               get_task_comm(name, tsk);
+               get_task_comm(name, current);
                audit_log_untrustedstring(ab, name);
                audit_log_format(ab, " data=");
                audit_log_n_hex(ab, data, size);
index 58cf665f597e00845454910934b9ce070f201d95..a625c29a2ea2aa3047cbb22ac919d82446d88aaa 100644 (file)
@@ -151,8 +151,7 @@ extern void             audit_log_link_denied(const char *operation);
 extern void                audit_log_lost(const char *message);
 
 extern int audit_log_task_context(struct audit_buffer *ab);
-extern void audit_log_task_info(struct audit_buffer *ab,
-                               struct task_struct *tsk);
+extern void audit_log_task_info(struct audit_buffer *ab);
 
 extern int                 audit_update_lsm_rules(void);
 
@@ -200,8 +199,7 @@ static inline int audit_log_task_context(struct audit_buffer *ab)
 {
        return 0;
 }
-static inline void audit_log_task_info(struct audit_buffer *ab,
-                                      struct task_struct *tsk)
+static inline void audit_log_task_info(struct audit_buffer *ab)
 { }
 #define audit_enabled AUDIT_OFF
 #endif /* CONFIG_AUDIT */
index d09298d3c2d2b6a82a5559b9de49a1bf3e3dd0d3..779671883349c1fea89df9dfbf477066b48b205e 100644 (file)
@@ -1096,10 +1096,11 @@ static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature
 
        if (audit_enabled == AUDIT_OFF)
                return;
+
        ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FEATURE_CHANGE);
        if (!ab)
                return;
-       audit_log_task_info(ab, current);
+       audit_log_task_info(ab);
        audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
                         audit_feature_names[which], !!old_feature, !!new_feature,
                         !!old_lock, !!new_lock, res);
@@ -2246,15 +2247,15 @@ out_null:
        audit_log_format(ab, " exe=(null)");
 }
 
-struct tty_struct *audit_get_tty(struct task_struct *tsk)
+struct tty_struct *audit_get_tty(void)
 {
        struct tty_struct *tty = NULL;
        unsigned long flags;
 
-       spin_lock_irqsave(&tsk->sighand->siglock, flags);
-       if (tsk->signal)
-               tty = tty_kref_get(tsk->signal->tty);
-       spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
+       spin_lock_irqsave(&current->sighand->siglock, flags);
+       if (current->signal)
+               tty = tty_kref_get(current->signal->tty);
+       spin_unlock_irqrestore(&current->sighand->siglock, flags);
        return tty;
 }
 
@@ -2263,25 +2264,24 @@ void audit_put_tty(struct tty_struct *tty)
        tty_kref_put(tty);
 }
 
-void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
+void audit_log_task_info(struct audit_buffer *ab)
 {
        const struct cred *cred;
-       char comm[sizeof(tsk->comm)];
+       char comm[sizeof(current->comm)];
        struct tty_struct *tty;
 
        if (!ab)
                return;
 
-       /* tsk == current */
        cred = current_cred();
-       tty = audit_get_tty(tsk);
+       tty = audit_get_tty();
        audit_log_format(ab,
                         " ppid=%d pid=%d auid=%u uid=%u gid=%u"
                         " euid=%u suid=%u fsuid=%u"
                         " egid=%u sgid=%u fsgid=%u tty=%s ses=%u",
-                        task_ppid_nr(tsk),
-                        task_tgid_nr(tsk),
-                        from_kuid(&init_user_ns, audit_get_loginuid(tsk)),
+                        task_ppid_nr(current),
+                        task_tgid_nr(current),
+                        from_kuid(&init_user_ns, audit_get_loginuid(current)),
                         from_kuid(&init_user_ns, cred->uid),
                         from_kgid(&init_user_ns, cred->gid),
                         from_kuid(&init_user_ns, cred->euid),
@@ -2291,11 +2291,11 @@ void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
                         from_kgid(&init_user_ns, cred->sgid),
                         from_kgid(&init_user_ns, cred->fsgid),
                         tty ? tty_name(tty) : "(none)",
-                        audit_get_sessionid(tsk));
+                        audit_get_sessionid(current));
        audit_put_tty(tty);
        audit_log_format(ab, " comm=");
-       audit_log_untrustedstring(ab, get_task_comm(comm, tsk));
-       audit_log_d_path_exe(ab, tsk->mm);
+       audit_log_untrustedstring(ab, get_task_comm(comm, current));
+       audit_log_d_path_exe(ab, current->mm);
        audit_log_task_context(ab);
 }
 EXPORT_SYMBOL(audit_log_task_info);
@@ -2316,7 +2316,7 @@ void audit_log_link_denied(const char *operation)
        if (!ab)
                return;
        audit_log_format(ab, "op=%s", operation);
-       audit_log_task_info(ab, current);
+       audit_log_task_info(ab);
        audit_log_format(ab, " res=0");
        audit_log_end(ab);
 }
index 0b5295aeaebb134fdba2f36890901b5a2a50a1bd..91421679a16889d75706d08dc7367ed5eee8812f 100644 (file)
@@ -264,7 +264,7 @@ extern struct audit_entry *audit_dupe_rule(struct audit_krule *old);
 extern void audit_log_d_path_exe(struct audit_buffer *ab,
                                 struct mm_struct *mm);
 
-extern struct tty_struct *audit_get_tty(struct task_struct *tsk);
+extern struct tty_struct *audit_get_tty(void);
 extern void audit_put_tty(struct tty_struct *tty);
 
 /* audit watch functions */
index 51e735aedf58770f519c52c869be15bbb3c250f6..6593a5207fb03f28a24bf1dfd6a52bcc77412024 100644 (file)
@@ -830,44 +830,6 @@ void audit_filter_inodes(struct task_struct *tsk, struct audit_context *ctx)
        rcu_read_unlock();
 }
 
-/* Transfer the audit context pointer to the caller, clearing it in the tsk's struct */
-static inline struct audit_context *audit_take_context(struct task_struct *tsk,
-                                                     int return_valid,
-                                                     long return_code)
-{
-       struct audit_context *context = tsk->audit_context;
-
-       if (!context)
-               return NULL;
-       context->return_valid = return_valid;
-
-       /*
-        * we need to fix up the return code in the audit logs if the actual
-        * return codes are later going to be fixed up by the arch specific
-        * signal handlers
-        *
-        * This is actually a test for:
-        * (rc == ERESTARTSYS ) || (rc == ERESTARTNOINTR) ||
-        * (rc == ERESTARTNOHAND) || (rc == ERESTART_RESTARTBLOCK)
-        *
-        * but is faster than a bunch of ||
-        */
-       if (unlikely(return_code <= -ERESTARTSYS) &&
-           (return_code >= -ERESTART_RESTARTBLOCK) &&
-           (return_code != -ENOIOCTLCMD))
-               context->return_code = -EINTR;
-       else
-               context->return_code  = return_code;
-
-       if (context->in_syscall && !context->dummy) {
-               audit_filter_syscall(tsk, context, &audit_filter_list[AUDIT_FILTER_EXIT]);
-               audit_filter_inodes(tsk, context);
-       }
-
-       audit_set_context(tsk, NULL);
-       return context;
-}
-
 static inline void audit_proctitle_free(struct audit_context *context)
 {
        kfree(context->proctitle.value);
@@ -1296,15 +1258,18 @@ static inline int audit_proctitle_rtrim(char *proctitle, int len)
        return len;
 }
 
-static void audit_log_proctitle(struct task_struct *tsk,
-                        struct audit_context *context)
+static void audit_log_proctitle(void)
 {
        int res;
        char *buf;
        char *msg = "(null)";
        int len = strlen(msg);
+       struct audit_context *context = audit_context();
        struct audit_buffer *ab;
 
+       if (!context || context->dummy)
+               return;
+
        ab = audit_log_start(context, GFP_KERNEL, AUDIT_PROCTITLE);
        if (!ab)
                return; /* audit_panic or being filtered */
@@ -1317,7 +1282,7 @@ static void audit_log_proctitle(struct task_struct *tsk,
                if (!buf)
                        goto out;
                /* Historically called this from procfs naming */
-               res = get_cmdline(tsk, buf, MAX_PROCTITLE_AUDIT_LEN);
+               res = get_cmdline(current, buf, MAX_PROCTITLE_AUDIT_LEN);
                if (res == 0) {
                        kfree(buf);
                        goto out;
@@ -1337,15 +1302,15 @@ out:
        audit_log_end(ab);
 }
 
-static void audit_log_exit(struct audit_context *context, struct task_struct *tsk)
+static void audit_log_exit(void)
 {
        int i, call_panic = 0;
+       struct audit_context *context = audit_context();
        struct audit_buffer *ab;
        struct audit_aux_data *aux;
        struct audit_names *n;
 
-       /* tsk == current */
-       context->personality = tsk->personality;
+       context->personality = current->personality;
 
        ab = audit_log_start(context, GFP_KERNEL, AUDIT_SYSCALL);
        if (!ab)
@@ -1367,7 +1332,7 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
                         context->argv[3],
                         context->name_count);
 
-       audit_log_task_info(ab, tsk);
+       audit_log_task_info(ab);
        audit_log_key(ab, context->filterkey);
        audit_log_end(ab);
 
@@ -1456,7 +1421,7 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
                audit_log_name(context, n, NULL, i++, &call_panic);
        }
 
-       audit_log_proctitle(tsk, context);
+       audit_log_proctitle();
 
        /* Send end of event record to help user space know we are finished */
        ab = audit_log_start(context, GFP_KERNEL, AUDIT_EOE);
@@ -1474,22 +1439,31 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
  */
 void __audit_free(struct task_struct *tsk)
 {
-       struct audit_context *context;
+       struct audit_context *context = tsk->audit_context;
 
-       context = audit_take_context(tsk, 0, 0);
        if (!context)
                return;
 
-       /* Check for system calls that do not go through the exit
-        * function (e.g., exit_group), then free context block.
-        * We use GFP_ATOMIC here because we might be doing this
-        * in the context of the idle thread */
-       /* that can happen only if we are called from do_exit() */
-       if (context->in_syscall && context->current_state == AUDIT_RECORD_CONTEXT)
-               audit_log_exit(context, tsk);
+       /* We are called either by do_exit() or the fork() error handling code;
+        * in the former case tsk == current and in the latter tsk is a
+        * random task_struct that doesn't doesn't have any meaningful data we
+        * need to log via audit_log_exit().
+        */
+       if (tsk == current && !context->dummy && context->in_syscall) {
+               context->return_valid = 0;
+               context->return_code = 0;
+
+               audit_filter_syscall(tsk, context,
+                                    &audit_filter_list[AUDIT_FILTER_EXIT]);
+               audit_filter_inodes(tsk, context);
+               if (context->current_state == AUDIT_RECORD_CONTEXT)
+                       audit_log_exit();
+       }
+
        if (!list_empty(&context->killed_trees))
                audit_kill_trees(&context->killed_trees);
 
+       audit_set_context(tsk, NULL);
        audit_free_context(context);
 }
 
@@ -1559,17 +1533,40 @@ void __audit_syscall_exit(int success, long return_code)
 {
        struct audit_context *context;
 
-       if (success)
-               success = AUDITSC_SUCCESS;
-       else
-               success = AUDITSC_FAILURE;
-
-       context = audit_take_context(current, success, return_code);
+       context = audit_context();
        if (!context)
                return;
 
-       if (context->in_syscall && context->current_state == AUDIT_RECORD_CONTEXT)
-               audit_log_exit(context, current);
+       if (!context->dummy && context->in_syscall) {
+               if (success)
+                       context->return_valid = AUDITSC_SUCCESS;
+               else
+                       context->return_valid = AUDITSC_FAILURE;
+
+               /*
+                * we need to fix up the return code in the audit logs if the
+                * actual return codes are later going to be fixed up by the
+                * arch specific signal handlers
+                *
+                * This is actually a test for:
+                * (rc == ERESTARTSYS ) || (rc == ERESTARTNOINTR) ||
+                * (rc == ERESTARTNOHAND) || (rc == ERESTART_RESTARTBLOCK)
+                *
+                * but is faster than a bunch of ||
+                */
+               if (unlikely(return_code <= -ERESTARTSYS) &&
+                   (return_code >= -ERESTART_RESTARTBLOCK) &&
+                   (return_code != -ENOIOCTLCMD))
+                       context->return_code = -EINTR;
+               else
+                       context->return_code  = return_code;
+
+               audit_filter_syscall(current, context,
+                                    &audit_filter_list[AUDIT_FILTER_EXIT]);
+               audit_filter_inodes(current, context);
+               if (context->current_state == AUDIT_RECORD_CONTEXT)
+                       audit_log_exit();
+       }
 
        context->in_syscall = 0;
        context->prio = context->state == AUDIT_RECORD_CONTEXT ? ~0ULL : 0;
@@ -1591,7 +1588,6 @@ void __audit_syscall_exit(int success, long return_code)
                kfree(context->filterkey);
                context->filterkey = NULL;
        }
-       audit_set_context(current, context);
 }
 
 static inline void handle_one(const struct inode *inode)
@@ -2025,7 +2021,7 @@ static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
        uid = from_kuid(&init_user_ns, task_uid(current));
        oldloginuid = from_kuid(&init_user_ns, koldloginuid);
        loginuid = from_kuid(&init_user_ns, kloginuid),
-       tty = audit_get_tty(current);
+       tty = audit_get_tty();
 
        audit_log_format(ab, "pid=%d uid=%u", task_tgid_nr(current), uid);
        audit_log_task_context(ab);
@@ -2046,7 +2042,6 @@ static void audit_log_set_loginuid(kuid_t koldloginuid, kuid_t kloginuid,
  */
 int audit_set_loginuid(kuid_t loginuid)
 {
-       struct task_struct *task = current;
        unsigned int oldsessionid, sessionid = AUDIT_SID_UNSET;
        kuid_t oldloginuid;
        int rc;
@@ -2065,8 +2060,8 @@ int audit_set_loginuid(kuid_t loginuid)
                        sessionid = (unsigned int)atomic_inc_return(&session_id);
        }
 
-       task->sessionid = sessionid;
-       task->loginuid = loginuid;
+       current->sessionid = sessionid;
+       current->loginuid = loginuid;
 out:
        audit_log_set_loginuid(oldloginuid, loginuid, oldsessionid, sessionid, rc);
        return rc;
index 99dd1d53fc35bea0847416a7140fc46e04150efb..af134588ab4e8dcbd1e68687fcf19f226e5dd3a3 100644 (file)
@@ -336,7 +336,7 @@ void ima_audit_measurement(struct integrity_iint_cache *iint,
        audit_log_untrustedstring(ab, filename);
        audit_log_format(ab, " hash=\"%s:%s\"", algo_name, hash);
 
-       audit_log_task_info(ab, current);
+       audit_log_task_info(ab);
        audit_log_end(ab);
 
        iint->flags |= IMA_AUDITED;