[PATCH] audit signal recipients
When auditing syscalls that send signals, log the pid and security
context for each target process. Optimize the data collection by
adding a counter for signal-related rules, and avoiding allocating an
aux struct unless we have more than one target process. For process
groups, collect pid/context data in blocks of 16. Move the
audit_signal_info() hook up in check_kill_permission() so we audit
attempts where permission is denied.
Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/kernel/audit.h b/kernel/audit.h
index a337023..815d6f5 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -83,6 +83,7 @@
u32 field_count;
char *filterkey; /* ties events to rules */
struct audit_field *fields;
+ struct audit_field *arch_f; /* quick access to arch field */
struct audit_field *inode_f; /* quick access to an inode field */
struct audit_watch *watch; /* associated watch */
struct list_head rlist; /* entry in audit_watch.rules list */
@@ -131,17 +132,19 @@
extern int selinux_audit_rule_update(void);
#ifdef CONFIG_AUDITSYSCALL
-extern void __audit_signal_info(int sig, struct task_struct *t);
-static inline void audit_signal_info(int sig, struct task_struct *t)
+extern int __audit_signal_info(int sig, struct task_struct *t);
+static inline int audit_signal_info(int sig, struct task_struct *t)
{
- if (unlikely(audit_pid && t->tgid == audit_pid))
- __audit_signal_info(sig, t);
+ if (unlikely((audit_pid && t->tgid == audit_pid) ||
+ (audit_signals && !audit_dummy_context())))
+ return __audit_signal_info(sig, t);
+ return 0;
}
extern enum audit_state audit_filter_inodes(struct task_struct *,
struct audit_context *);
extern void audit_set_auditable(struct audit_context *);
#else
-#define audit_signal_info(s,t)
+#define audit_signal_info(s,t) AUDIT_DISABLED
#define audit_filter_inodes(t,c) AUDIT_DISABLED
#define audit_set_auditable(c)
#endif
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 3749193..6c61263 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -311,6 +311,43 @@
return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall);
}
+static inline int audit_match_class_bits(int class, u32 *mask)
+{
+ int i;
+
+ if (classes[class]) {
+ for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
+ if (mask[i] & classes[class][i])
+ return 0;
+ }
+ return 1;
+}
+
+static int audit_match_signal(struct audit_entry *entry)
+{
+ struct audit_field *arch = entry->rule.arch_f;
+
+ if (!arch) {
+ /* When arch is unspecified, we must check both masks on biarch
+ * as syscall number alone is ambiguous. */
+ return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
+ entry->rule.mask) &&
+ audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
+ entry->rule.mask));
+ }
+
+ switch(audit_classify_arch(arch->val)) {
+ case 0: /* native */
+ return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
+ entry->rule.mask));
+ case 1: /* 32bit on biarch */
+ return (audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
+ entry->rule.mask));
+ default:
+ return 1;
+ }
+}
+
/* Common user-space to kernel rule translation. */
static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule)
{
@@ -429,6 +466,7 @@
err = -EINVAL;
goto exit_free;
}
+ entry->rule.arch_f = f;
break;
case AUDIT_PERM:
if (f->val & ~15)
@@ -519,7 +557,6 @@
case AUDIT_FSGID:
case AUDIT_LOGINUID:
case AUDIT_PERS:
- case AUDIT_ARCH:
case AUDIT_MSGTYPE:
case AUDIT_PPID:
case AUDIT_DEVMAJOR:
@@ -531,6 +568,9 @@
case AUDIT_ARG2:
case AUDIT_ARG3:
break;
+ case AUDIT_ARCH:
+ entry->rule.arch_f = f;
+ break;
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
@@ -1221,6 +1261,9 @@
#ifdef CONFIG_AUDITSYSCALL
if (!dont_count)
audit_n_rules++;
+
+ if (!audit_match_signal(entry))
+ audit_signals++;
#endif
mutex_unlock(&audit_filter_mutex);
@@ -1294,6 +1337,9 @@
#ifdef CONFIG_AUDITSYSCALL
if (!dont_count)
audit_n_rules--;
+
+ if (!audit_match_signal(entry))
+ audit_signals--;
#endif
mutex_unlock(&audit_filter_mutex);
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 2243c55..6aff0df 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -89,6 +89,9 @@
/* number of audit rules */
int audit_n_rules;
+/* determines whether we collect data for signals sent */
+int audit_signals;
+
/* When fs/namei.c:getname() is called, we store the pointer in name and
* we don't let putname() free it (instead we free all of the saved
* pointers at syscall exit time).
@@ -114,6 +117,9 @@
#define AUDIT_AUX_IPCPERM 0
+/* Number of target pids per aux struct. */
+#define AUDIT_AUX_PIDS 16
+
struct audit_aux_data_mq_open {
struct audit_aux_data d;
int oflag;
@@ -181,6 +187,13 @@
struct vfsmount *mnt;
};
+struct audit_aux_data_pids {
+ struct audit_aux_data d;
+ pid_t target_pid[AUDIT_AUX_PIDS];
+ u32 target_sid[AUDIT_AUX_PIDS];
+ int pid_count;
+};
+
/* The per-task audit context. */
struct audit_context {
int dummy; /* must be the first element */
@@ -201,6 +214,7 @@
struct vfsmount * pwdmnt;
struct audit_context *previous; /* For nested syscalls */
struct audit_aux_data *aux;
+ struct audit_aux_data *aux_pids;
/* Save things to print about task_struct */
pid_t pid, ppid;
@@ -657,6 +671,10 @@
context->aux = aux->next;
kfree(aux);
}
+ while ((aux = context->aux_pids)) {
+ context->aux_pids = aux->next;
+ kfree(aux);
+ }
}
static inline void audit_zero_context(struct audit_context *context,
@@ -798,6 +816,29 @@
audit_log_task_context(ab);
}
+static int audit_log_pid_context(struct audit_context *context, pid_t pid,
+ u32 sid)
+{
+ struct audit_buffer *ab;
+ char *s = NULL;
+ u32 len;
+ int rc = 0;
+
+ ab = audit_log_start(context, GFP_KERNEL, AUDIT_OBJ_PID);
+ if (!ab)
+ return 1;
+
+ if (selinux_sid_to_string(sid, &s, &len)) {
+ audit_log_format(ab, "opid=%d obj=(none)", pid);
+ rc = 1;
+ } else
+ audit_log_format(ab, "opid=%d obj=%s", pid, s);
+ audit_log_end(ab);
+ kfree(s);
+
+ return rc;
+}
+
static void audit_log_exit(struct audit_context *context, struct task_struct *tsk)
{
int i, call_panic = 0;
@@ -976,23 +1017,21 @@
audit_log_end(ab);
}
- if (context->target_pid) {
- ab =audit_log_start(context, GFP_KERNEL, AUDIT_OBJ_PID);
- if (ab) {
- char *s = NULL, *t;
- u32 len;
- if (selinux_sid_to_string(context->target_sid,
- &s, &len))
- t = "(none)";
- else
- t = s;
- audit_log_format(ab, "opid=%d obj=%s",
- context->target_pid, t);
- audit_log_end(ab);
- kfree(s);
- }
+ for (aux = context->aux_pids; aux; aux = aux->next) {
+ struct audit_aux_data_pids *axs = (void *)aux;
+ int i;
+
+ for (i = 0; i < axs->pid_count; i++)
+ if (audit_log_pid_context(context, axs->target_pid[i],
+ axs->target_sid[i]))
+ call_panic = 1;
}
+ if (context->target_pid &&
+ audit_log_pid_context(context, context->target_pid,
+ context->target_sid))
+ call_panic = 1;
+
if (context->pwd && context->pwdmnt) {
ab = audit_log_start(context, GFP_KERNEL, AUDIT_CWD);
if (ab) {
@@ -1213,7 +1252,10 @@
} else {
audit_free_names(context);
audit_free_aux(context);
+ context->aux = NULL;
+ context->aux_pids = NULL;
context->target_pid = 0;
+ context->target_sid = 0;
kfree(context->filterkey);
context->filterkey = NULL;
tsk->audit_context = context;
@@ -1947,15 +1989,17 @@
* If the audit subsystem is being terminated, record the task (pid)
* and uid that is doing that.
*/
-void __audit_signal_info(int sig, struct task_struct *t)
+int __audit_signal_info(int sig, struct task_struct *t)
{
+ struct audit_aux_data_pids *axp;
+ struct task_struct *tsk = current;
+ struct audit_context *ctx = tsk->audit_context;
extern pid_t audit_sig_pid;
extern uid_t audit_sig_uid;
extern u32 audit_sig_sid;
- if (sig == SIGTERM || sig == SIGHUP || sig == SIGUSR1) {
- struct task_struct *tsk = current;
- struct audit_context *ctx = tsk->audit_context;
+ if (audit_pid && t->tgid == audit_pid &&
+ (sig == SIGTERM || sig == SIGHUP || sig == SIGUSR1)) {
audit_sig_pid = tsk->pid;
if (ctx)
audit_sig_uid = ctx->loginuid;
@@ -1963,4 +2007,33 @@
audit_sig_uid = tsk->uid;
selinux_get_task_sid(tsk, &audit_sig_sid);
}
+
+ if (!audit_signals) /* audit_context checked in wrapper */
+ return 0;
+
+ /* optimize the common case by putting first signal recipient directly
+ * in audit_context */
+ if (!ctx->target_pid) {
+ ctx->target_pid = t->tgid;
+ selinux_get_task_sid(t, &ctx->target_sid);
+ return 0;
+ }
+
+ axp = (void *)ctx->aux_pids;
+ if (!axp || axp->pid_count == AUDIT_AUX_PIDS) {
+ axp = kzalloc(sizeof(*axp), GFP_ATOMIC);
+ if (!axp)
+ return -ENOMEM;
+
+ axp->d.type = AUDIT_OBJ_PID;
+ axp->d.next = ctx->aux_pids;
+ ctx->aux_pids = (void *)axp;
+ }
+ BUG_ON(axp->pid_count > AUDIT_AUX_PIDS);
+
+ axp->target_pid[axp->pid_count] = t->tgid;
+ selinux_get_task_sid(t, &axp->target_sid[axp->pid_count]);
+ axp->pid_count++;
+
+ return 0;
}
diff --git a/kernel/signal.c b/kernel/signal.c
index 2ac3a66..c43a3f1 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -497,6 +497,11 @@
int error = -EINVAL;
if (!valid_signal(sig))
return error;
+
+ error = audit_signal_info(sig, t); /* Let audit system see the signal */
+ if (error)
+ return error;
+
error = -EPERM;
if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
&& ((sig != SIGCONT) ||
@@ -506,10 +511,7 @@
&& !capable(CAP_KILL))
return error;
- error = security_task_kill(t, info, sig, 0);
- if (!error)
- audit_signal_info(sig, t); /* Let audit system see the signal */
- return error;
+ return security_task_kill(t, info, sig, 0);
}
/* forward decl */