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[89.229.233.64]) by smtp.gmail.com with ESMTPSA id z188sm239622lfa.141.2020.11.26.01.22.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Nov 2020 01:22:53 -0800 (PST) From: mariusz.dudek@gmail.com X-Google-Original-From: mariuszx.dudek@intel.com To: andrii.nakryiko@gmail.com, magnus.karlsson@intel.com, bjorn.topel@intel.com, ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org, jonathan.lemon@gmail.com Cc: bpf@vger.kernel.org, Mariusz Dudek Subject: [PATCH v4 bpf-next 1/2] libbpf: separate XDP program load with xsk socket creation Date: Thu, 26 Nov 2020 10:22:47 +0100 Message-Id: <20201126092248.6192-2-mariuszx.dudek@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20201126092248.6192-1-mariuszx.dudek@intel.com> References: <20201126092248.6192-1-mariuszx.dudek@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: Mariusz Dudek Add support for separation of eBPF program load and xsk socket creation. This is needed for use-case when you want to privide as little privileges as possible to the data plane application that will handle xsk socket creation and incoming traffic. With this patch the data entity container can be run with only CAP_NET_RAW capability to fulfill its purpose of creating xsk socket and handling packages. In case your umem is larger or equal process limit for MEMLOCK you need either increase the limit or CAP_IPC_LOCK capability. To resolve privileges issue two APIs are introduced: - xsk_setup_xdp_prog - loads the built in XDP program. It can also return xsks_map_fd which is needed by unprivileged process to update xsks_map with AF_XDP socket "fd" - xsk_socket__update_xskmap - inserts an AF_XDP socket into an xskmap for a particular xsk_socket Signed-off-by: Mariusz Dudek --- tools/lib/bpf/libbpf.map | 2 + tools/lib/bpf/xsk.c | 92 ++++++++++++++++++++++++++++++++++++---- tools/lib/bpf/xsk.h | 5 +++ 3 files changed, 90 insertions(+), 9 deletions(-) diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 29ff4807b909..d939d5ac092e 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -345,4 +345,6 @@ LIBBPF_0.3.0 { btf__parse_split; btf__new_empty_split; btf__new_split; + xsk_setup_xdp_prog; + xsk_socket__update_xskmap; } LIBBPF_0.2.0; diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c index 9bc537d0b92d..4b051ec7cfbb 100644 --- a/tools/lib/bpf/xsk.c +++ b/tools/lib/bpf/xsk.c @@ -566,8 +566,35 @@ static int xsk_set_bpf_maps(struct xsk_socket *xsk) &xsk->fd, 0); } -static int xsk_setup_xdp_prog(struct xsk_socket *xsk) +static int xsk_create_xsk_struct(int ifindex, struct xsk_socket *xsk) { + char ifname[IFNAMSIZ]; + struct xsk_ctx *ctx; + char *interface; + + ctx = calloc(1, sizeof(*ctx)); + if (!ctx) + return -ENOMEM; + + interface = if_indextoname(ifindex, &ifname[0]); + if (!interface) { + free(ctx); + return -errno; + } + + ctx->ifindex = ifindex; + strncpy(ctx->ifname, ifname, IFNAMSIZ - 1); + ctx->ifname[IFNAMSIZ - 1] = 0; + + xsk->ctx = ctx; + + return 0; +} + +static int __xsk_setup_xdp_prog(struct xsk_socket *_xdp, + int *xsks_map_fd) +{ + struct xsk_socket *xsk = _xdp; struct xsk_ctx *ctx = xsk->ctx; __u32 prog_id = 0; int err; @@ -584,8 +611,7 @@ static int xsk_setup_xdp_prog(struct xsk_socket *xsk) err = xsk_load_xdp_prog(xsk); if (err) { - xsk_delete_bpf_maps(xsk); - return err; + goto err_load_xdp_prog; } } else { ctx->prog_fd = bpf_prog_get_fd_by_id(prog_id); @@ -598,15 +624,29 @@ static int xsk_setup_xdp_prog(struct xsk_socket *xsk) } } - if (xsk->rx) + if (xsk->rx) { err = xsk_set_bpf_maps(xsk); - if (err) { - xsk_delete_bpf_maps(xsk); - close(ctx->prog_fd); - return err; + if (err) { + if (!prog_id) { + goto err_set_bpf_maps; + } else { + close(ctx->prog_fd); + return err; + } + } } + if (xsks_map_fd) + *xsks_map_fd = ctx->xsks_map_fd; return 0; + +err_set_bpf_maps: + close(ctx->prog_fd); + bpf_set_link_xdp_fd(ctx->ifindex, -1, 0); +err_load_xdp_prog: + xsk_delete_bpf_maps(xsk); + + return err; } static struct xsk_ctx *xsk_get_ctx(struct xsk_umem *umem, int ifindex, @@ -689,6 +729,40 @@ static struct xsk_ctx *xsk_create_ctx(struct xsk_socket *xsk, return ctx; } +static void xsk_destroy_xsk_struct(struct xsk_socket *xsk) +{ + free(xsk->ctx); + free(xsk); +} + +int xsk_socket__update_xskmap(struct xsk_socket *xsk, int fd) +{ + xsk->ctx->xsks_map_fd = fd; + return xsk_set_bpf_maps(xsk); +} + +int xsk_setup_xdp_prog(int ifindex, int *xsks_map_fd) +{ + struct xsk_socket *xsk; + int res; + + xsk = calloc(1, sizeof(*xsk)); + if (!xsk) + return -ENOMEM; + + res = xsk_create_xsk_struct(ifindex, xsk); + if (res) { + free(xsk); + return -EINVAL; + } + + res = __xsk_setup_xdp_prog(xsk, xsks_map_fd); + + xsk_destroy_xsk_struct(xsk); + + return res; +} + int xsk_socket__create_shared(struct xsk_socket **xsk_ptr, const char *ifname, __u32 queue_id, struct xsk_umem *umem, @@ -838,7 +912,7 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr, ctx->prog_fd = -1; if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) { - err = xsk_setup_xdp_prog(xsk); + err = __xsk_setup_xdp_prog(xsk, NULL); if (err) goto out_mmap_tx; } diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h index 1719a327e5f9..10b4259f8875 100644 --- a/tools/lib/bpf/xsk.h +++ b/tools/lib/bpf/xsk.h @@ -207,6 +207,11 @@ struct xsk_umem_config { __u32 flags; }; +LIBBPF_API int xsk_setup_xdp_prog(int ifindex, + int *xsks_map_fd); +LIBBPF_API int xsk_socket__update_xskmap(struct xsk_socket *xsk, + int xsks_map_fd); + /* Flags for the libbpf_flags field. */ #define XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD (1 << 0)