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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include "bpf-foreign.h"
#include "bpf-program.h"
#include "cgroup.h"
#include "memory-util.h"
#include "missing_magic.h"
#include "mountpoint-util.h"
#include "set.h"
#include "stat-util.h"
typedef struct BPFForeignKey BPFForeignKey;
struct BPFForeignKey {
uint32_t prog_id;
uint32_t attach_type;
};
static int bpf_foreign_key_new(uint32_t prog_id,
enum bpf_attach_type attach_type,
BPFForeignKey **ret) {
_cleanup_free_ BPFForeignKey *p = NULL;
assert(ret);
p = new(BPFForeignKey, 1);
if (!p)
return log_oom();
*p = (BPFForeignKey) {
.prog_id = prog_id,
.attach_type = attach_type,
};
*ret = TAKE_PTR(p);
return 0;
}
static int bpf_foreign_key_compare_func(const BPFForeignKey *a, const BPFForeignKey *b) {
int r = CMP(a->prog_id, b->prog_id);
if (r != 0)
return r;
return CMP(a->attach_type, b->attach_type);
}
static void bpf_foreign_key_hash_func(const BPFForeignKey *p, struct siphash *h) {
siphash24_compress(&p->prog_id, sizeof(p->prog_id), h);
siphash24_compress(&p->attach_type, sizeof(p->attach_type), h);
}
DEFINE_PRIVATE_HASH_OPS_FULL(bpf_foreign_by_key_hash_ops,
BPFForeignKey, bpf_foreign_key_hash_func, bpf_foreign_key_compare_func, free,
BPFProgram, bpf_program_free);
static int attach_programs(Unit *u, const char *path, Hashmap* foreign_by_key, uint32_t attach_flags) {
const BPFForeignKey *key;
BPFProgram *prog;
int r;
assert(u);
HASHMAP_FOREACH_KEY(prog, key, foreign_by_key) {
r = bpf_program_cgroup_attach(prog, key->attach_type, path, attach_flags);
if (r < 0)
return log_unit_error_errno(u, r, "Attaching foreign BPF program to cgroup %s failed: %m", path);
}
return 0;
}
/*
* Prepare foreign BPF program for installation:
* - Load the program from BPF filesystem to the kernel;
* - Store program FD identified by program ID and attach type in the unit.
*/
static int bpf_foreign_prepare(
Unit *u,
enum bpf_attach_type attach_type,
const char *bpffs_path) {
_cleanup_(bpf_program_freep) BPFProgram *prog = NULL;
_cleanup_free_ BPFForeignKey *key = NULL;
uint32_t prog_id;
int r;
assert(u);
assert(bpffs_path);
r = path_is_fs_type(bpffs_path, BPF_FS_MAGIC);
if (r < 0)
return log_unit_error_errno(u, r,
"Failed to determine filesystem type of %s: %m", bpffs_path);
if (r == 0)
return log_unit_error_errno(u, SYNTHETIC_ERRNO(EINVAL),
"Path in BPF filesystem is expected.");
r = bpf_program_new_from_bpffs_path(bpffs_path, &prog);
if (r < 0)
return log_unit_error_errno(u, r, "Failed to create foreign BPFProgram: %m");
r = bpf_program_get_id_by_fd(prog->kernel_fd, &prog_id);
if (r < 0)
return log_unit_error_errno(u, r, "Failed to get BPF program id by fd: %m");
r = bpf_foreign_key_new(prog_id, attach_type, &key);
if (r < 0)
return log_unit_error_errno(u, r,
"Failed to create foreign BPF program key from path '%s': %m", bpffs_path);
r = hashmap_ensure_put(&u->bpf_foreign_by_key, &bpf_foreign_by_key_hash_ops, key, prog);
if (r == -EEXIST) {
log_unit_warning_errno(u, r, "Foreign BPF program already exists, ignoring: %m");
return 0;
}
if (r < 0)
return log_unit_error_errno(u, r, "Failed to put foreign BPFProgram into map: %m");
TAKE_PTR(key);
TAKE_PTR(prog);
return 0;
}
int bpf_foreign_install(Unit *u) {
_cleanup_free_ char *cgroup_path = NULL;
CGroupBPFForeignProgram *p;
CGroupContext *cc;
int r;
assert(u);
cc = unit_get_cgroup_context(u);
if (!cc)
return 0;
r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, u->cgroup_path, NULL, &cgroup_path);
if (r < 0)
return log_unit_error_errno(u, r, "Failed to get cgroup path: %m");
LIST_FOREACH(programs, p, cc->bpf_foreign_programs) {
r = bpf_foreign_prepare(u, p->attach_type, p->bpffs_path);
if (r < 0)
return log_unit_error_errno(u, r, "Failed to prepare foreign BPF hashmap: %m");
}
r = attach_programs(u, cgroup_path, u->bpf_foreign_by_key, BPF_F_ALLOW_MULTI);
if (r < 0)
return log_unit_error_errno(u, r, "Failed to install foreign BPF programs: %m");
return 0;
}
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