Martin,
Thank you for the detailed feedback.
Can a separate global lock/mutex (not the lock_sock) be acquired first before using the sock pointer in the kfuncs?
Sure. I will add the mutex around the socket operations. As for the single global sock pointer, I wanted to keep it simple in this patch series to fulfill the current use case. I agree it might be overkill for now to add the bpf map and such.
Is it better to set sk_sndtimeo in bpf_kfunc_init_sock() ? All these new kfunc should have the KF_SLEEPABLE flag. bpf_testmod_exit() should probably do this NULL check and sock_release() also.
Ack. I will add this.
nit. Can "struct sockaddr_storage addr;" be directly used instead of a char array?
When using "struct sockaddr_storage addr;" directly, the BPF program fails to load with the following error message.
libbpf: prog 'kernel_connect': BPF program load failed: Invalid argument libbpf: prog 'kernel_connect': -- BEGIN PROG LOAD LOG -- 0: R1=ctx() R10=fp0 ; return bpf_kfunc_call_kernel_connect(args); @ sock_addr_kern.c:26 0: (85) call bpf_kfunc_call_kernel_connect#99994 arg#0 pointer type STRUCT addr_args must point to scalar, or struct with scalar processed 1 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 -- END PROG LOAD LOG -- libbpf: prog 'kernel_connect': failed to load: -22 libbpf: failed to load object 'sock_addr_kern' libbpf: failed to load BPF skeleton 'sock_addr_kern': -22 load_sock_addr_kern:FAIL:skel unexpected error: -22 test_sock_addr:FAIL:load_sock_addr_kern unexpected error: -1 (errno 22) #288 sock_addr:FAIL
-Jordan
On Tue, Apr 16, 2024 at 2:43 AM Martin KaFai Lau martin.lau@linux.dev wrote:
On 4/12/24 9:52 AM, Jordan Rife wrote:
This patch adds a set of kfuncs to bpf_testmod that can be used to manipulate a socket from kernel space.
Signed-off-by: Jordan Rife jrife@google.com
.../selftests/bpf/bpf_testmod/bpf_testmod.c | 139 ++++++++++++++++++ .../bpf/bpf_testmod/bpf_testmod_kfunc.h | 27 ++++ 2 files changed, 166 insertions(+)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c index 39ad96a18123f..663df8148097e 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c @@ -10,18 +10,29 @@ #include <linux/percpu-defs.h> #include <linux/sysfs.h> #include <linux/tracepoint.h> +#include <linux/net.h> +#include <linux/socket.h> +#include <linux/nsproxy.h> +#include <linux/inet.h> +#include <linux/in.h> +#include <linux/in6.h> +#include <linux/un.h> +#include <net/sock.h> #include "bpf_testmod.h" #include "bpf_testmod_kfunc.h"
#define CREATE_TRACE_POINTS #include "bpf_testmod-events.h"
+#define CONNECT_TIMEOUT_SEC 1
typedef int (*func_proto_typedef)(long); typedef int (*func_proto_typedef_nested1)(func_proto_typedef); typedef int (*func_proto_typedef_nested2)(func_proto_typedef_nested1);
DEFINE_PER_CPU(int, bpf_testmod_ksym_percpu) = 123; long bpf_testmod_test_struct_arg_result;
+static struct socket *sock;
struct bpf_testmod_struct_arg_1 { int a; @@ -494,6 +505,124 @@ __bpf_kfunc static u32 bpf_kfunc_call_test_static_unused_arg(u32 arg, u32 unused return arg; }
+__bpf_kfunc int bpf_kfunc_init_sock(struct init_sock_args *args) +{
int proto;if (sock)pr_warn("%s called without releasing old sock", __func__);hmm...this global sock pointer is quite unease. e.g. what if multiple tasks trying to use init/close/connect... in parallel.
Storing sock in a bpf map will be better but that may be overkill for testing. Can a separate global lock/mutex (not the lock_sock) be acquired first before using the sock pointer in the kfuncs?
switch (args->af) {case AF_INET:case AF_INET6:proto = args->type == SOCK_STREAM ? IPPROTO_TCP : IPPROTO_UDP;break;case AF_UNIX:proto = PF_UNIX;break;default:pr_err("invalid address family %d\n", args->af);return -EINVAL;}return sock_create_kern(&init_net, args->af, args->type, proto, &sock);+}
+__bpf_kfunc void bpf_kfunc_close_sock(void) +{
if (sock) {sock_release(sock);bpf_testmod_exit() should probably do this NULL check and sock_release() also.
sock = NULL;}+}
+__bpf_kfunc int bpf_kfunc_call_kernel_connect(struct addr_args *args) +{
/* Set timeout for call to kernel_connect() to prevent it from hanging,* and consider the connection attempt failed if it returns* -EINPROGRESS.*/sock->sk->sk_sndtimeo = CONNECT_TIMEOUT_SEC * HZ;Is it better to set sk_sndtimeo in bpf_kfunc_init_sock() ?
return kernel_connect(sock, (struct sockaddr *)&args->addr,args->addrlen, 0);+}
+__bpf_kfunc int bpf_kfunc_call_kernel_bind(struct addr_args *args) +{
return kernel_bind(sock, (struct sockaddr *)&args->addr, args->addrlen);+}
+__bpf_kfunc int bpf_kfunc_call_kernel_listen(void) +{
return kernel_listen(sock, 128);+}
+__bpf_kfunc int bpf_kfunc_call_kernel_sendmsg(struct sendmsg_args *args) +{
struct msghdr msg = {.msg_name = &args->addr.addr,.msg_namelen = args->addr.addrlen,};struct kvec iov;int err;iov.iov_base = args->msg;iov.iov_len = args->msglen;err = kernel_sendmsg(sock, &msg, &iov, 1, args->msglen);args->addr.addrlen = msg.msg_namelen;return err;+}
+__bpf_kfunc int bpf_kfunc_call_sock_sendmsg(struct sendmsg_args *args) +{
struct msghdr msg = {.msg_name = &args->addr.addr,.msg_namelen = args->addr.addrlen,};struct kvec iov;int err;iov.iov_base = args->msg;iov.iov_len = args->msglen;iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &iov, 1, args->msglen);err = sock_sendmsg(sock, &msg);args->addr.addrlen = msg.msg_namelen;return err;+}
+__bpf_kfunc int bpf_kfunc_call_kernel_getsockname(struct addr_args *args) +{
int err;err = kernel_getsockname(sock, (struct sockaddr *)&args->addr);if (err < 0)goto out;args->addrlen = err;err = 0;+out:
return err;+}
+__bpf_kfunc int bpf_kfunc_call_kernel_getpeername(struct addr_args *args) +{
int err;err = kernel_getpeername(sock, (struct sockaddr *)&args->addr);if (err < 0)goto out;args->addrlen = err;err = 0;+out:
return err;+}
- BTF_KFUNCS_START(bpf_testmod_check_kfunc_ids) BTF_ID_FLAGS(func, bpf_testmod_test_mod_kfunc) BTF_ID_FLAGS(func, bpf_kfunc_call_test1)
@@ -520,6 +649,15 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_test_ref, KF_TRUSTED_ARGS | KF_RCU) BTF_ID_FLAGS(func, bpf_kfunc_call_test_destructive, KF_DESTRUCTIVE) BTF_ID_FLAGS(func, bpf_kfunc_call_test_static_unused_arg) BTF_ID_FLAGS(func, bpf_kfunc_call_test_offset) +BTF_ID_FLAGS(func, bpf_kfunc_init_sock) +BTF_ID_FLAGS(func, bpf_kfunc_close_sock) +BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_connect) +BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_bind) +BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_listen) +BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_sendmsg) +BTF_ID_FLAGS(func, bpf_kfunc_call_sock_sendmsg) +BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_getsockname) +BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_getpeername)
All these new kfunc should have the KF_SLEEPABLE flag.
BTF_KFUNCS_END(bpf_testmod_check_kfunc_ids)
static int bpf_testmod_ops_init(struct btf *btf) @@ -650,6 +788,7 @@ static int bpf_testmod_init(void) return ret; if (bpf_fentry_test1(0) < 0) return -EINVAL;
sock = NULL; return sysfs_create_bin_file(kernel_kobj, &bin_attr_bpf_testmod_file);diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h index 7c664dd610597..cdf7769a7d8ca 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h @@ -64,6 +64,22 @@ struct prog_test_fail3 { char arr2[]; };
+struct init_sock_args {
int af;int type;+};
+struct addr_args {
char addr[sizeof(struct __kernel_sockaddr_storage)];nit. Can "struct sockaddr_storage addr;" be directly used instead of a char array?
int addrlen;+};
+struct sendmsg_args {
struct addr_args addr;char msg[10];int msglen;+};
- struct prog_test_ref_kfunc * bpf_kfunc_call_test_acquire(unsigned long *scalar_ptr) __ksym; void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p) __ksym;
@@ -106,4 +122,15 @@ void bpf_kfunc_call_test_fail3(struct prog_test_fail3 *p); void bpf_kfunc_call_test_mem_len_fail1(void *mem, int len);
void bpf_kfunc_common_test(void) __ksym;
+int bpf_kfunc_init_sock(struct init_sock_args *args) __ksym; +void bpf_kfunc_close_sock(void) __ksym; +int bpf_kfunc_call_kernel_connect(struct addr_args *args) __ksym; +int bpf_kfunc_call_kernel_bind(struct addr_args *args) __ksym; +int bpf_kfunc_call_kernel_listen(void) __ksym; +int bpf_kfunc_call_kernel_sendmsg(struct sendmsg_args *args) __ksym; +int bpf_kfunc_call_sock_sendmsg(struct sendmsg_args *args) __ksym; +int bpf_kfunc_call_kernel_getsockname(struct addr_args *args) __ksym; +int bpf_kfunc_call_kernel_getpeername(struct addr_args *args) __ksym;
- #endif /* _BPF_TESTMOD_KFUNC_H */