This introduces the BPF return value for SECCOMP_RET_KILL_PROCESS to kill
an entire process. This cannot yet be reached by seccomp, but it changes
the default-kill behavior (for unknown return values) from kill-thread to
kill-process.
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
include/uapi/linux/seccomp.h | 18 ++++++++++--------
kernel/seccomp.c | 22 ++++++++++++++++------
2 files changed, 26 insertions(+), 14 deletions(-)
diff --git a/include/uapi/linux/seccomp.h b/include/uapi/linux/seccomp.h
index 5a03f699eb17..7e77c92df78a 100644
--- a/include/uapi/linux/seccomp.h
+++ b/include/uapi/linux/seccomp.h
@@ -22,18 +22,20 @@
/*
* All BPF programs must return a 32-bit value.
* The bottom 16-bits are for optional return data.
- * The upper 16-bits are ordered from least permissive values to most.
+ * The upper 16-bits are ordered from least permissive values to most,
+ * as a signed value (so 0x8000000 is negative).
*
* The ordering ensures that a min_t() over composed return values always
* selects the least permissive choice.
*/
-#define SECCOMP_RET_KILL_THREAD 0x00000000U /* kill the thread */
-#define SECCOMP_RET_KILL SECCOMP_RET_KILL_THREAD
-#define SECCOMP_RET_TRAP 0x00030000U /* disallow and force a SIGSYS */
-#define SECCOMP_RET_ERRNO 0x00050000U /* returns an errno */
-#define SECCOMP_RET_TRACE 0x7ff00000U /* pass to a tracer or disallow */
-#define SECCOMP_RET_LOG 0x7ffc0000U /* allow after logging */
-#define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */
+#define SECCOMP_RET_KILL_PROCESS 0x80000000U /* kill the process */
+#define SECCOMP_RET_KILL_THREAD 0x00000000U /* kill the thread */
+#define SECCOMP_RET_KILL SECCOMP_RET_KILL_THREAD
+#define SECCOMP_RET_TRAP 0x00030000U /* disallow and force a SIGSYS */
+#define SECCOMP_RET_ERRNO 0x00050000U /* returns an errno */
+#define SECCOMP_RET_TRACE 0x7ff00000U /* pass to a tracer or disallow */
+#define SECCOMP_RET_LOG 0x7ffc0000U /* allow after logging */
+#define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */
/* Masks for the return value sections. */
#define SECCOMP_RET_ACTION 0x7fff0000U
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 95ac54cff00f..5c7299b9d953 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -192,7 +192,7 @@ static u32 seccomp_run_filters(const struct seccomp_data *sd,
/* Ensure unexpected behavior doesn't result in failing open. */
if (unlikely(WARN_ON(f == NULL)))
- return SECCOMP_RET_KILL_THREAD;
+ return SECCOMP_RET_KILL_PROCESS;
if (!sd) {
populate_seccomp_data(&sd_local);
@@ -529,14 +529,16 @@ static void seccomp_send_sigsys(int syscall, int reason)
#endif /* CONFIG_SECCOMP_FILTER */
/* For use with seccomp_actions_logged */
-#define SECCOMP_LOG_KILL_THREAD (1 << 0)
+#define SECCOMP_LOG_KILL_PROCESS (1 << 0)
+#define SECCOMP_LOG_KILL_THREAD (1 << 1)
#define SECCOMP_LOG_TRAP (1 << 2)
#define SECCOMP_LOG_ERRNO (1 << 3)
#define SECCOMP_LOG_TRACE (1 << 4)
#define SECCOMP_LOG_LOG (1 << 5)
#define SECCOMP_LOG_ALLOW (1 << 6)
-static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_THREAD |
+static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
+ SECCOMP_LOG_KILL_THREAD |
SECCOMP_LOG_TRAP |
SECCOMP_LOG_ERRNO |
SECCOMP_LOG_TRACE |
@@ -563,8 +565,11 @@ static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
log = seccomp_actions_logged & SECCOMP_LOG_LOG;
break;
case SECCOMP_RET_KILL_THREAD:
- default:
log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
+ break;
+ case SECCOMP_RET_KILL_PROCESS:
+ default:
+ log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
}
/*
@@ -719,10 +724,12 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
return 0;
case SECCOMP_RET_KILL_THREAD:
+ case SECCOMP_RET_KILL_PROCESS:
default:
seccomp_log(this_syscall, SIGSYS, action, true);
/* Dump core only if this is the last remaining thread. */
- if (get_nr_threads(current) == 1) {
+ if (action == SECCOMP_RET_KILL_PROCESS ||
+ get_nr_threads(current) == 1) {
siginfo_t info;
/* Show the original registers in the dump. */
@@ -731,7 +738,10 @@ static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
seccomp_init_siginfo(&info, this_syscall, data);
do_coredump(&info);
}
- do_exit(SIGSYS);
+ if (action == SECCOMP_RET_KILL_PROCESS)
+ do_group_exit(SIGSYS);
+ else
+ do_exit(SIGSYS);
}
unreachable();
--
2.7.4
--
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