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-rw-r--r--Documentation/sysctl/kernel.txt1
-rw-r--r--Documentation/userspace-api/seccomp_filter.rst16
-rw-r--r--kernel/seccomp.c51
3 files changed, 68 insertions, 0 deletions
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index bac23c198360..995c42cf86ba 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -74,6 +74,7 @@ show up in /proc/sys/kernel:
- reboot-cmd [ SPARC only ]
- rtsig-max
- rtsig-nr
+- seccomp/ ==> Documentation/userspace-api/seccomp_filter.rst
- sem
- sem_next_id [ sysv ipc ]
- sg-big-buff [ generic SCSI device (sg) ]
diff --git a/Documentation/userspace-api/seccomp_filter.rst b/Documentation/userspace-api/seccomp_filter.rst
index f71eb5ef1f2d..35fc7cbf1d95 100644
--- a/Documentation/userspace-api/seccomp_filter.rst
+++ b/Documentation/userspace-api/seccomp_filter.rst
@@ -169,7 +169,23 @@ The ``samples/seccomp/`` directory contains both an x86-specific example
and a more generic example of a higher level macro interface for BPF
program generation.
+Sysctls
+=======
+
+Seccomp's sysctl files can be found in the ``/proc/sys/kernel/seccomp/``
+directory. Here's a description of each file in that directory:
+
+``actions_avail``:
+ A read-only ordered list of seccomp return values (refer to the
+ ``SECCOMP_RET_*`` macros above) in string form. The ordering, from
+ left-to-right, is the least permissive return value to the most
+ permissive return value.
+ The list represents the set of seccomp return values supported
+ by the kernel. A userspace program may use this list to
+ determine if the actions found in the ``seccomp.h``, when the
+ program was built, differs from the set of actions actually
+ supported in the current running kernel.
Adding architecture support
===========================
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 1f3347fc2605..5f19f41e4e50 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -17,11 +17,13 @@
#include <linux/audit.h>
#include <linux/compat.h>
#include <linux/coredump.h>
+#include <linux/kmemleak.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/seccomp.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
+#include <linux/sysctl.h>
#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
#include <asm/syscall.h>
@@ -934,3 +936,52 @@ out:
return ret;
}
#endif
+
+#ifdef CONFIG_SYSCTL
+
+/* Human readable action names for friendly sysctl interaction */
+#define SECCOMP_RET_KILL_NAME "kill"
+#define SECCOMP_RET_TRAP_NAME "trap"
+#define SECCOMP_RET_ERRNO_NAME "errno"
+#define SECCOMP_RET_TRACE_NAME "trace"
+#define SECCOMP_RET_ALLOW_NAME "allow"
+
+static const char seccomp_actions_avail[] = SECCOMP_RET_KILL_NAME " "
+ SECCOMP_RET_TRAP_NAME " "
+ SECCOMP_RET_ERRNO_NAME " "
+ SECCOMP_RET_TRACE_NAME " "
+ SECCOMP_RET_ALLOW_NAME;
+
+static struct ctl_path seccomp_sysctl_path[] = {
+ { .procname = "kernel", },
+ { .procname = "seccomp", },
+ { }
+};
+
+static struct ctl_table seccomp_sysctl_table[] = {
+ {
+ .procname = "actions_avail",
+ .data = (void *) &seccomp_actions_avail,
+ .maxlen = sizeof(seccomp_actions_avail),
+ .mode = 0444,
+ .proc_handler = proc_dostring,
+ },
+ { }
+};
+
+static int __init seccomp_sysctl_init(void)
+{
+ struct ctl_table_header *hdr;
+
+ hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
+ if (!hdr)
+ pr_warn("seccomp: sysctl registration failed\n");
+ else
+ kmemleak_not_leak(hdr);
+
+ return 0;
+}
+
+device_initcall(seccomp_sysctl_init)
+
+#endif /* CONFIG_SYSCTL */