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Message-ID: <20191209070633.GA32462@ircssh-2.c.rugged-nimbus-611.internal>
Date: Mon, 9 Dec 2019 07:06:36 +0000
From: Sargun Dhillon <sargun@...gun.me>
To: linux-kernel@...r.kernel.org,
containers@...ts.linux-foundation.org, linux-api@...r.kernel.org,
linux-fsdevel@...r.kernel.org
Cc: tycho@...ho.ws, jannh@...gle.com, cyphar@...har.com,
christian.brauner@...ntu.com, oleg@...hat.com, luto@...capital.net,
viro@...iv.linux.org.uk
Subject: [PATCH v2 3/4] samples: split generalized user-trap code into helper
file
This moves the code for setting up a syscall interceptor with user
notification and sending the user notification file descriptor over a
socket using SCM_RIGHTS into a file that can be shared between multiple
samples.
Signed-off-by: Sargun Dhillon <sargun@...gun.me>
---
samples/seccomp/Makefile | 6 ++-
samples/seccomp/user-trap-helper.c | 84 +++++++++++++++++++++++++++++
samples/seccomp/user-trap-helper.h | 13 +++++
samples/seccomp/user-trap.c | 85 +-----------------------------
4 files changed, 103 insertions(+), 85 deletions(-)
create mode 100644 samples/seccomp/user-trap-helper.c
create mode 100644 samples/seccomp/user-trap-helper.h
diff --git a/samples/seccomp/Makefile b/samples/seccomp/Makefile
index 009775b52538..82b7347318d1 100644
--- a/samples/seccomp/Makefile
+++ b/samples/seccomp/Makefile
@@ -16,9 +16,13 @@ HOSTCFLAGS_bpf-direct.o += -I$(objtree)/usr/include
HOSTCFLAGS_bpf-direct.o += -idirafter $(objtree)/include
bpf-direct-objs := bpf-direct.o
+
+HOSTCFLAGS_user-trap-helper.o += -I$(objtree)/usr/include
+HOSTCFLAGS_user-trap-helper.o += -idirafter $(objtree)/include
+
HOSTCFLAGS_user-trap.o += -I$(objtree)/usr/include
HOSTCFLAGS_user-trap.o += -idirafter $(objtree)/include
-user-trap-objs := user-trap.o
+user-trap-objs := user-trap.o user-trap-helper.o
# Try to match the kernel target.
ifndef CONFIG_64BIT
diff --git a/samples/seccomp/user-trap-helper.c b/samples/seccomp/user-trap-helper.c
new file mode 100644
index 000000000000..f91ae9d947c5
--- /dev/null
+++ b/samples/seccomp/user-trap-helper.c
@@ -0,0 +1,84 @@
+#include <linux/seccomp.h>
+#include <linux/filter.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/syscall.h>
+#include <sys/socket.h>
+#include "user-trap-helper.h"
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
+
+int user_trap_syscall(int nr, unsigned int flags)
+{
+ struct sock_filter filter[] = {
+ BPF_STMT(BPF_LD+BPF_W+BPF_ABS,
+ offsetof(struct seccomp_data, nr)),
+ BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, nr, 0, 1),
+ BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_USER_NOTIF),
+ BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW),
+ };
+
+ struct sock_fprog prog = {
+ .len = (unsigned short)ARRAY_SIZE(filter),
+ .filter = filter,
+ };
+
+ return seccomp(SECCOMP_SET_MODE_FILTER, flags, &prog);
+}
+
+int send_fd(int sock, int fd)
+{
+ struct msghdr msg = {};
+ struct cmsghdr *cmsg;
+ char buf[CMSG_SPACE(sizeof(int))] = {0}, c = 'c';
+ struct iovec io = {
+ .iov_base = &c,
+ .iov_len = 1,
+ };
+
+ msg.msg_iov = &io;
+ msg.msg_iovlen = 1;
+ msg.msg_control = buf;
+ msg.msg_controllen = sizeof(buf);
+ cmsg = CMSG_FIRSTHDR(&msg);
+ cmsg->cmsg_level = SOL_SOCKET;
+ cmsg->cmsg_type = SCM_RIGHTS;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+ *((int *)CMSG_DATA(cmsg)) = fd;
+ msg.msg_controllen = cmsg->cmsg_len;
+
+ if (sendmsg(sock, &msg, 0) < 0) {
+ perror("sendmsg");
+ return -1;
+ }
+
+ return 0;
+}
+
+int recv_fd(int sock)
+{
+ struct msghdr msg = {};
+ struct cmsghdr *cmsg;
+ char buf[CMSG_SPACE(sizeof(int))] = {0}, c = 'c';
+ struct iovec io = {
+ .iov_base = &c,
+ .iov_len = 1,
+ };
+
+ msg.msg_iov = &io;
+ msg.msg_iovlen = 1;
+ msg.msg_control = buf;
+ msg.msg_controllen = sizeof(buf);
+
+ if (recvmsg(sock, &msg, 0) < 0) {
+ perror("recvmsg");
+ return -1;
+ }
+
+ cmsg = CMSG_FIRSTHDR(&msg);
+
+ return *((int *)CMSG_DATA(cmsg));
+}
diff --git a/samples/seccomp/user-trap-helper.h b/samples/seccomp/user-trap-helper.h
new file mode 100644
index 000000000000..a5ebda25fdfe
--- /dev/null
+++ b/samples/seccomp/user-trap-helper.h
@@ -0,0 +1,13 @@
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <errno.h>
+
+static inline int seccomp(unsigned int op, unsigned int flags, void *args)
+{
+ errno = 0;
+ return syscall(__NR_seccomp, op, flags, args);
+}
+
+int user_trap_syscall(int nr, unsigned int flags);
+int send_fd(int sock, int fd);
+int recv_fd(int sock);
diff --git a/samples/seccomp/user-trap.c b/samples/seccomp/user-trap.c
index 6d0125ca8af7..1b6526587456 100644
--- a/samples/seccomp/user-trap.c
+++ b/samples/seccomp/user-trap.c
@@ -5,101 +5,18 @@
#include <errno.h>
#include <fcntl.h>
#include <string.h>
-#include <stddef.h>
#include <sys/sysmacros.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/mman.h>
-#include <sys/syscall.h>
#include <sys/user.h>
#include <sys/ioctl.h>
-#include <sys/ptrace.h>
#include <sys/mount.h>
#include <linux/limits.h>
-#include <linux/filter.h>
#include <linux/seccomp.h>
-
-#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
-
-static int seccomp(unsigned int op, unsigned int flags, void *args)
-{
- errno = 0;
- return syscall(__NR_seccomp, op, flags, args);
-}
-
-static int send_fd(int sock, int fd)
-{
- struct msghdr msg = {};
- struct cmsghdr *cmsg;
- char buf[CMSG_SPACE(sizeof(int))] = {0}, c = 'c';
- struct iovec io = {
- .iov_base = &c,
- .iov_len = 1,
- };
-
- msg.msg_iov = &io;
- msg.msg_iovlen = 1;
- msg.msg_control = buf;
- msg.msg_controllen = sizeof(buf);
- cmsg = CMSG_FIRSTHDR(&msg);
- cmsg->cmsg_level = SOL_SOCKET;
- cmsg->cmsg_type = SCM_RIGHTS;
- cmsg->cmsg_len = CMSG_LEN(sizeof(int));
- *((int *)CMSG_DATA(cmsg)) = fd;
- msg.msg_controllen = cmsg->cmsg_len;
-
- if (sendmsg(sock, &msg, 0) < 0) {
- perror("sendmsg");
- return -1;
- }
-
- return 0;
-}
-
-static int recv_fd(int sock)
-{
- struct msghdr msg = {};
- struct cmsghdr *cmsg;
- char buf[CMSG_SPACE(sizeof(int))] = {0}, c = 'c';
- struct iovec io = {
- .iov_base = &c,
- .iov_len = 1,
- };
-
- msg.msg_iov = &io;
- msg.msg_iovlen = 1;
- msg.msg_control = buf;
- msg.msg_controllen = sizeof(buf);
-
- if (recvmsg(sock, &msg, 0) < 0) {
- perror("recvmsg");
- return -1;
- }
-
- cmsg = CMSG_FIRSTHDR(&msg);
-
- return *((int *)CMSG_DATA(cmsg));
-}
-
-static int user_trap_syscall(int nr, unsigned int flags)
-{
- struct sock_filter filter[] = {
- BPF_STMT(BPF_LD+BPF_W+BPF_ABS,
- offsetof(struct seccomp_data, nr)),
- BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, nr, 0, 1),
- BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_USER_NOTIF),
- BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW),
- };
-
- struct sock_fprog prog = {
- .len = (unsigned short)ARRAY_SIZE(filter),
- .filter = filter,
- };
-
- return seccomp(SECCOMP_SET_MODE_FILTER, flags, &prog);
-}
+#include "user-trap-helper.h"
static int handle_req(struct seccomp_notif *req,
struct seccomp_notif_resp *resp, int listener)
--
2.20.1
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