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authorLennart Poettering <lennart@poettering.net>2012-07-17 04:17:53 +0200
committerLennart Poettering <lennart@poettering.net>2012-07-17 04:17:53 +0200
commit8351ceaea9480d9c2979aa2ff0f4982cfdfef58d (patch)
treefc1f94e5a17679960774da386a54d145255e4ef1 /src/shared/linux
parentcd96b3b86abb4a88cac2722bdfb6e5d4413f6831 (diff)
execute: support syscall filtering using seccomp filters
Diffstat (limited to 'src/shared/linux')
-rw-r--r--src/shared/linux/seccomp-bpf.h76
-rw-r--r--src/shared/linux/seccomp.h47
2 files changed, 123 insertions, 0 deletions
diff --git a/src/shared/linux/seccomp-bpf.h b/src/shared/linux/seccomp-bpf.h
new file mode 100644
index 0000000000..1e3d136739
--- /dev/null
+++ b/src/shared/linux/seccomp-bpf.h
@@ -0,0 +1,76 @@
+/*
+ * seccomp example for x86 (32-bit and 64-bit) with BPF macros
+ *
+ * Copyright (c) 2012 The Chromium OS Authors <chromium-os-dev@chromium.org>
+ * Authors:
+ * Will Drewry <wad@chromium.org>
+ * Kees Cook <keescook@chromium.org>
+ *
+ * The code may be used by anyone for any purpose, and can serve as a
+ * starting point for developing applications using mode 2 seccomp.
+ */
+#ifndef _SECCOMP_BPF_H_
+#define _SECCOMP_BPF_H_
+
+#include <stdio.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <signal.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/prctl.h>
+
+#include <linux/unistd.h>
+#include <linux/audit.h>
+#include <linux/filter.h>
+#include <linux/seccomp.h>
+
+#ifndef SECCOMP_MODE_FILTER
+# define SECCOMP_MODE_FILTER 2 /* uses user-supplied filter. */
+# define SECCOMP_RET_KILL 0x00000000U /* kill the task immediately */
+# define SECCOMP_RET_TRAP 0x00030000U /* disallow and force a SIGSYS */
+# define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */
+struct seccomp_data {
+ int nr;
+ __u32 arch;
+ __u64 instruction_pointer;
+ __u64 args[6];
+};
+#endif
+#ifndef SYS_SECCOMP
+# define SYS_SECCOMP 1
+#endif
+
+#define syscall_nr (offsetof(struct seccomp_data, nr))
+#define arch_nr (offsetof(struct seccomp_data, arch))
+
+#if defined(__i386__)
+# define REG_SYSCALL REG_EAX
+# define ARCH_NR AUDIT_ARCH_I386
+#elif defined(__x86_64__)
+# define REG_SYSCALL REG_RAX
+# define ARCH_NR AUDIT_ARCH_X86_64
+#else
+# warning "Platform does not support seccomp filter yet"
+# define REG_SYSCALL 0
+# define ARCH_NR 0
+#endif
+
+#define VALIDATE_ARCHITECTURE \
+ BPF_STMT(BPF_LD+BPF_W+BPF_ABS, arch_nr), \
+ BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, ARCH_NR, 1, 0), \
+ BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL)
+
+#define EXAMINE_SYSCALL \
+ BPF_STMT(BPF_LD+BPF_W+BPF_ABS, syscall_nr)
+
+#define ALLOW_SYSCALL(name) \
+ BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, __NR_##name, 0, 1), \
+ BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW)
+
+#define _KILL_PROCESS \
+ BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL)
+
+#endif /* _SECCOMP_BPF_H_ */
diff --git a/src/shared/linux/seccomp.h b/src/shared/linux/seccomp.h
new file mode 100644
index 0000000000..9c03683fa0
--- /dev/null
+++ b/src/shared/linux/seccomp.h
@@ -0,0 +1,47 @@
+#ifndef _LINUX_SECCOMP_H
+#define _LINUX_SECCOMP_H
+
+
+#include <linux/types.h>
+
+
+/* Valid values for seccomp.mode and prctl(PR_SET_SECCOMP, <mode>) */
+#define SECCOMP_MODE_DISABLED 0 /* seccomp is not in use. */
+#define SECCOMP_MODE_STRICT 1 /* uses hard-coded filter. */
+#define SECCOMP_MODE_FILTER 2 /* uses user-supplied filter. */
+
+/*
+ * 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 ordering ensures that a min_t() over composed return values always
+ * selects the least permissive choice.
+ */
+#define SECCOMP_RET_KILL 0x00000000U /* kill the task immediately */
+#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_ALLOW 0x7fff0000U /* allow */
+
+/* Masks for the return value sections. */
+#define SECCOMP_RET_ACTION 0x7fff0000U
+#define SECCOMP_RET_DATA 0x0000ffffU
+
+/**
+ * struct seccomp_data - the format the BPF program executes over.
+ * @nr: the system call number
+ * @arch: indicates system call convention as an AUDIT_ARCH_* value
+ * as defined in <linux/audit.h>.
+ * @instruction_pointer: at the time of the system call.
+ * @args: up to 6 system call arguments always stored as 64-bit values
+ * regardless of the architecture.
+ */
+struct seccomp_data {
+ int nr;
+ __u32 arch;
+ __u64 instruction_pointer;
+ __u64 args[6];
+};
+
+#endif /* _LINUX_SECCOMP_H */