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shared: add bpf-program helpers
Add helpers to: - Create new BPFProgram instance from a path in bpf filesystem and bpf attach type; - Pin a program to bpf fs; - Get BPF program ID by BPF program FD.
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@ -12,6 +12,26 @@
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#include "missing_syscall.h"
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#include "path-util.h"
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/* struct bpf_prog_info info must be initialized since its value is both input and output
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* for BPF_OBJ_GET_INFO_BY_FD syscall. */
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static int bpf_program_get_info_by_fd(int prog_fd, struct bpf_prog_info *info, uint32_t info_len) {
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union bpf_attr attr;
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/* Explicitly memset to zero since some compilers may produce non-zero-initialized padding when
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* structured initialization is used.
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* Refer to https://github.com/systemd/systemd/issues/18164
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*/
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zero(attr);
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attr.info.bpf_fd = prog_fd;
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attr.info.info_len = info_len;
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attr.info.info = PTR_TO_UINT64(info);
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if (bpf(BPF_OBJ_GET_INFO_BY_FD, &attr, sizeof(attr)) < 0)
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return -errno;
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return 0;
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}
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int bpf_program_new(uint32_t prog_type, BPFProgram **ret) {
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_cleanup_(bpf_program_unrefp) BPFProgram *p = NULL;
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@ -28,6 +48,38 @@ int bpf_program_new(uint32_t prog_type, BPFProgram **ret) {
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return 0;
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}
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int bpf_program_new_from_bpffs_path(const char *path, BPFProgram **ret) {
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_cleanup_(bpf_program_unrefp) BPFProgram *p = NULL;
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struct bpf_prog_info info = {};
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int r;
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assert(path);
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assert(ret);
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p = new(BPFProgram, 1);
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if (!p)
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return -ENOMEM;
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*p = (BPFProgram) {
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.prog_type = BPF_PROG_TYPE_UNSPEC,
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.n_ref = 1,
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.kernel_fd = -1,
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};
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r = bpf_program_load_from_bpf_fs(p, path);
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if (r < 0)
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return r;
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r = bpf_program_get_info_by_fd(p->kernel_fd, &info, sizeof(info));
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if (r < 0)
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return r;
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p->prog_type = info.type;
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*ret = TAKE_PTR(p);
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return 0;
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}
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static BPFProgram *bpf_program_free(BPFProgram *p) {
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assert(p);
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@ -254,3 +306,31 @@ int bpf_map_lookup_element(int fd, const void *key, void *value) {
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return 0;
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}
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int bpf_program_pin(int prog_fd, const char *bpffs_path) {
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union bpf_attr attr;
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zero(attr);
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attr.pathname = PTR_TO_UINT64((void *) bpffs_path);
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attr.bpf_fd = prog_fd;
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if (bpf(BPF_OBJ_PIN, &attr, sizeof(attr)) < 0)
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return -errno;
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return 0;
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}
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int bpf_program_get_id_by_fd(int prog_fd, uint32_t *ret_id) {
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struct bpf_prog_info info = {};
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int r;
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assert(ret_id);
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r = bpf_program_get_info_by_fd(prog_fd, &info, sizeof(info));
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if (r < 0)
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return r;
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*ret_id = info.id;
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return 0;
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};
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@ -26,8 +26,9 @@ struct BPFProgram {
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};
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int bpf_program_new(uint32_t prog_type, BPFProgram **ret);
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BPFProgram *bpf_program_unref(BPFProgram *p);
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int bpf_program_new_from_bpffs_path(const char *path, BPFProgram **ret);
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BPFProgram *bpf_program_ref(BPFProgram *p);
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BPFProgram *bpf_program_unref(BPFProgram *p);
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int bpf_program_add_instructions(BPFProgram *p, const struct bpf_insn *insn, size_t count);
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int bpf_program_load_kernel(BPFProgram *p, char *log_buf, size_t log_size);
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@ -35,6 +36,8 @@ int bpf_program_load_from_bpf_fs(BPFProgram *p, const char *path);
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int bpf_program_cgroup_attach(BPFProgram *p, int type, const char *path, uint32_t flags);
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int bpf_program_cgroup_detach(BPFProgram *p);
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int bpf_program_pin(int prog_fd, const char *bpffs_path);
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int bpf_program_get_id_by_fd(int prog_fd, uint32_t *ret_id);
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int bpf_map_new(enum bpf_map_type type, size_t key_size, size_t value_size, size_t max_entries, uint32_t flags);
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int bpf_map_update_element(int fd, const void *key, void *value);
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