Adding upstream version 252.22.upstream/252.22

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 500 insertions, 0 deletions

diff --git a/src/shared/bpf-program.c b/src/shared/bpf-program.c
new file mode 100644
index 0000000..57a009a
--- /dev/null
+++ b/src/shared/bpf-program.c
@@ -0,0 +1,500 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "bpf-program.h"
+#include "errno-util.h"
+#include "escape.h"
+#include "fd-util.h"
+#include "memory-util.h"
+#include "missing_syscall.h"
+#include "path-util.h"
+#include "serialize.h"
+#include "string-table.h"
+
+static const char *const bpf_cgroup_attach_type_table[__MAX_BPF_ATTACH_TYPE] = {
+        [BPF_CGROUP_INET_INGRESS] =     "ingress",
+        [BPF_CGROUP_INET_EGRESS] =      "egress",
+        [BPF_CGROUP_INET_SOCK_CREATE] = "sock_create",
+        [BPF_CGROUP_SOCK_OPS] =         "sock_ops",
+        [BPF_CGROUP_DEVICE] =           "device",
+        [BPF_CGROUP_INET4_BIND] =       "bind4",
+        [BPF_CGROUP_INET6_BIND] =       "bind6",
+        [BPF_CGROUP_INET4_CONNECT] =    "connect4",
+        [BPF_CGROUP_INET6_CONNECT] =    "connect6",
+        [BPF_CGROUP_INET4_POST_BIND] =  "post_bind4",
+        [BPF_CGROUP_INET6_POST_BIND] =  "post_bind6",
+        [BPF_CGROUP_UDP4_SENDMSG] =     "sendmsg4",
+        [BPF_CGROUP_UDP6_SENDMSG] =     "sendmsg6",
+        [BPF_CGROUP_SYSCTL] =           "sysctl",
+        [BPF_CGROUP_UDP4_RECVMSG] =     "recvmsg4",
+        [BPF_CGROUP_UDP6_RECVMSG] =     "recvmsg6",
+        [BPF_CGROUP_GETSOCKOPT] =       "getsockopt",
+        [BPF_CGROUP_SETSOCKOPT] =       "setsockopt",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(bpf_cgroup_attach_type, int);
+
+DEFINE_HASH_OPS_WITH_KEY_DESTRUCTOR(bpf_program_hash_ops, void, trivial_hash_func, trivial_compare_func, bpf_program_free);
+
+BPFProgram *bpf_program_free(BPFProgram *p) {
+        if (!p)
+                return NULL;
+        /* Unfortunately, the kernel currently doesn't implicitly detach BPF programs from their cgroups when the last
+         * fd to the BPF program is closed. This has nasty side-effects since this means that abnormally terminated
+         * programs that attached one of their BPF programs to a cgroup will leave this program pinned for good with
+         * zero chance of recovery, until the cgroup is removed. This is particularly problematic if the cgroup in
+         * question is the root cgroup (or any other cgroup belonging to a service that cannot be restarted during
+         * operation, such as dbus), as the memory for the BPF program can only be reclaimed through a reboot. To
+         * counter this, we track closely to which cgroup a program was attached to and will detach it on our own
+         * whenever we close the BPF fd. */
+        (void) bpf_program_cgroup_detach(p);
+
+        safe_close(p->kernel_fd);
+        free(p->prog_name);
+        free(p->instructions);
+        free(p->attached_path);
+
+        return mfree(p);
+}
+
+ /* struct bpf_prog_info info must be initialized since its value is both input and output
+  * for BPF_OBJ_GET_INFO_BY_FD syscall. */
+static int bpf_program_get_info_by_fd(int prog_fd, struct bpf_prog_info *info, uint32_t info_len) {
+        union bpf_attr attr;
+
+        /* Explicitly memset to zero since some compilers may produce non-zero-initialized padding when
+         * structured initialization is used.
+         * Refer to https://github.com/systemd/systemd/issues/18164
+         */
+        zero(attr);
+        attr.info.bpf_fd = prog_fd;
+        attr.info.info_len = info_len;
+        attr.info.info = PTR_TO_UINT64(info);
+
+        return RET_NERRNO(bpf(BPF_OBJ_GET_INFO_BY_FD, &attr, sizeof(attr)));
+}
+
+int bpf_program_new(uint32_t prog_type, const char *prog_name, BPFProgram **ret) {
+        _cleanup_(bpf_program_freep) BPFProgram *p = NULL;
+        _cleanup_free_ char *name = NULL;
+
+        if (prog_name) {
+                if (strlen(prog_name) >= BPF_OBJ_NAME_LEN)
+                        return -ENAMETOOLONG;
+
+                name = strdup(prog_name);
+                if (!name)
+                        return -ENOMEM;
+        }
+
+        p = new(BPFProgram, 1);
+        if (!p)
+                return -ENOMEM;
+
+        *p = (BPFProgram) {
+                .prog_type = prog_type,
+                .kernel_fd = -1,
+                .prog_name = TAKE_PTR(name),
+        };
+
+        *ret = TAKE_PTR(p);
+
+        return 0;
+}
+
+int bpf_program_new_from_bpffs_path(const char *path, BPFProgram **ret) {
+        _cleanup_(bpf_program_freep) BPFProgram *p = NULL;
+        struct bpf_prog_info info = {};
+        int r;
+
+        assert(path);
+        assert(ret);
+
+        p = new(BPFProgram, 1);
+        if (!p)
+                return -ENOMEM;
+
+        *p = (BPFProgram) {
+                .prog_type = BPF_PROG_TYPE_UNSPEC,
+                .kernel_fd = -1,
+        };
+
+        r = bpf_program_load_from_bpf_fs(p, path);
+        if (r < 0)
+                return r;
+
+        r = bpf_program_get_info_by_fd(p->kernel_fd, &info, sizeof(info));
+        if (r < 0)
+                return r;
+
+        p->prog_type = info.type;
+        *ret = TAKE_PTR(p);
+
+        return 0;
+}
+
+
+int bpf_program_add_instructions(BPFProgram *p, const struct bpf_insn *instructions, size_t count) {
+
+        assert(p);
+
+        if (p->kernel_fd >= 0) /* don't allow modification after we uploaded things to the kernel */
+                return -EBUSY;
+
+        if (!GREEDY_REALLOC(p->instructions, p->n_instructions + count))
+                return -ENOMEM;
+
+        memcpy(p->instructions + p->n_instructions, instructions, sizeof(struct bpf_insn) * count);
+        p->n_instructions += count;
+
+        return 0;
+}
+
+int bpf_program_load_kernel(BPFProgram *p, char *log_buf, size_t log_size) {
+        union bpf_attr attr;
+
+        assert(p);
+
+        if (p->kernel_fd >= 0) { /* make this idempotent */
+                memzero(log_buf, log_size);
+                return 0;
+        }
+
+        // FIXME: Clang doesn't 0-pad with structured initialization, causing
+        // the kernel to reject the bpf_attr as invalid. See:
+        // https://github.com/torvalds/linux/blob/v5.9/kernel/bpf/syscall.c#L65
+        // Ideally it should behave like GCC, so that we can remove these workarounds.
+        zero(attr);
+        attr.prog_type = p->prog_type;
+        attr.insns = PTR_TO_UINT64(p->instructions);
+        attr.insn_cnt = p->n_instructions;
+        attr.license = PTR_TO_UINT64("GPL");
+        attr.log_buf = PTR_TO_UINT64(log_buf);
+        attr.log_level = !!log_buf;
+        attr.log_size = log_size;
+        if (p->prog_name)
+                strncpy(attr.prog_name, p->prog_name, BPF_OBJ_NAME_LEN - 1);
+
+        p->kernel_fd = bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
+        if (p->kernel_fd < 0)
+                return -errno;
+
+        return 0;
+}
+
+int bpf_program_load_from_bpf_fs(BPFProgram *p, const char *path) {
+        union bpf_attr attr;
+
+        assert(p);
+
+        if (p->kernel_fd >= 0) /* don't overwrite an assembled or loaded program */
+                return -EBUSY;
+
+        zero(attr);
+        attr.pathname = PTR_TO_UINT64(path);
+
+        p->kernel_fd = bpf(BPF_OBJ_GET, &attr, sizeof(attr));
+        if (p->kernel_fd < 0)
+                return -errno;
+
+        return 0;
+}
+
+int bpf_program_cgroup_attach(BPFProgram *p, int type, const char *path, uint32_t flags) {
+        _cleanup_free_ char *copy = NULL;
+        _cleanup_close_ int fd = -1;
+        union bpf_attr attr;
+        int r;
+
+        assert(p);
+        assert(type >= 0);
+        assert(path);
+
+        if (!IN_SET(flags, 0, BPF_F_ALLOW_OVERRIDE, BPF_F_ALLOW_MULTI))
+                return -EINVAL;
+
+        /* We need to track which cgroup the program is attached to, and we can only track one attachment, hence let's
+        * refuse this early. */
+        if (p->attached_path) {
+                if (!path_equal(p->attached_path, path))
+                        return -EBUSY;
+                if (p->attached_type != type)
+                        return -EBUSY;
+                if (p->attached_flags != flags)
+                        return -EBUSY;
+
+                /* Here's a shortcut: if we previously attached this program already, then we don't have to do so
+                 * again. Well, with one exception: if we are in BPF_F_ALLOW_OVERRIDE mode then someone else might have
+                 * replaced our program since the last time, hence let's reattach it again, just to be safe. In flags
+                 * == 0 mode this is not an issue since nobody else can replace our program in that case, and in flags
+                 * == BPF_F_ALLOW_MULTI mode any other's program would be installed in addition to ours hence ours
+                 * would remain in effect. */
+                if (flags != BPF_F_ALLOW_OVERRIDE)
+                        return 0;
+        }
+
+        /* Ensure we have a kernel object for this. */
+        r = bpf_program_load_kernel(p, NULL, 0);
+        if (r < 0)
+                return r;
+
+        copy = strdup(path);
+        if (!copy)
+                return -ENOMEM;
+
+        fd = open(path, O_DIRECTORY|O_RDONLY|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        zero(attr);
+        attr.attach_type = type;
+        attr.target_fd = fd;
+        attr.attach_bpf_fd = p->kernel_fd;
+        attr.attach_flags = flags;
+
+        if (bpf(BPF_PROG_ATTACH, &attr, sizeof(attr)) < 0)
+                return -errno;
+
+        free_and_replace(p->attached_path, copy);
+        p->attached_type = type;
+        p->attached_flags = flags;
+
+        return 0;
+}
+
+int bpf_program_cgroup_detach(BPFProgram *p) {
+        _cleanup_close_ int fd = -1;
+
+        assert(p);
+
+        if (!p->attached_path)
+                return -EUNATCH;
+
+        fd = open(p->attached_path, O_DIRECTORY|O_RDONLY|O_CLOEXEC);
+        if (fd < 0) {
+                if (errno != ENOENT)
+                        return -errno;
+
+                /* If the cgroup does not exist anymore, then we don't have to explicitly detach, it got detached
+                 * implicitly by the removal, hence don't complain */
+
+        } else {
+                union bpf_attr attr;
+
+                zero(attr);
+                attr.attach_type = p->attached_type;
+                attr.target_fd = fd;
+                attr.attach_bpf_fd = p->kernel_fd;
+
+                if (bpf(BPF_PROG_DETACH, &attr, sizeof(attr)) < 0)
+                        return -errno;
+        }
+
+        p->attached_path = mfree(p->attached_path);
+
+        return 0;
+}
+
+int bpf_map_new(enum bpf_map_type type, size_t key_size, size_t value_size, size_t max_entries, uint32_t flags) {
+        union bpf_attr attr;
+
+        zero(attr);
+        attr.map_type = type;
+        attr.key_size = key_size;
+        attr.value_size = value_size;
+        attr.max_entries = max_entries;
+        attr.map_flags = flags;
+
+        return RET_NERRNO(bpf(BPF_MAP_CREATE, &attr, sizeof(attr)));
+}
+
+int bpf_map_update_element(int fd, const void *key, void *value) {
+        union bpf_attr attr;
+
+        zero(attr);
+        attr.map_fd = fd;
+        attr.key = PTR_TO_UINT64(key);
+        attr.value = PTR_TO_UINT64(value);
+
+        return RET_NERRNO(bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr)));
+}
+
+int bpf_map_lookup_element(int fd, const void *key, void *value) {
+        union bpf_attr attr;
+
+        zero(attr);
+        attr.map_fd = fd;
+        attr.key = PTR_TO_UINT64(key);
+        attr.value = PTR_TO_UINT64(value);
+
+        return RET_NERRNO(bpf(BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr)));
+}
+
+int bpf_program_pin(int prog_fd, const char *bpffs_path) {
+        union bpf_attr attr;
+
+        zero(attr);
+        attr.pathname = PTR_TO_UINT64((void *) bpffs_path);
+        attr.bpf_fd = prog_fd;
+
+        return RET_NERRNO(bpf(BPF_OBJ_PIN, &attr, sizeof(attr)));
+}
+
+int bpf_program_get_id_by_fd(int prog_fd, uint32_t *ret_id) {
+        struct bpf_prog_info info = {};
+        int r;
+
+        assert(ret_id);
+
+        r = bpf_program_get_info_by_fd(prog_fd, &info, sizeof(info));
+        if (r < 0)
+                return r;
+
+        *ret_id = info.id;
+
+        return 0;
+};
+
+int bpf_program_serialize_attachment(
+                FILE *f,
+                FDSet *fds,
+                const char *key,
+                BPFProgram *p) {
+
+        _cleanup_free_ char *escaped = NULL;
+        int copy, r;
+
+        if (!p || !p->attached_path)
+                return 0;
+
+        assert(p->kernel_fd >= 0);
+
+        escaped = cescape(p->attached_path);
+        if (!escaped)
+                return -ENOMEM;
+
+        copy = fdset_put_dup(fds, p->kernel_fd);
+        if (copy < 0)
+                return log_error_errno(copy, "Failed to add BPF kernel fd to serialize: %m");
+
+        r = serialize_item_format(
+                        f,
+                        key,
+                        "%i %s %s",
+                        copy,
+                        bpf_cgroup_attach_type_to_string(p->attached_type),
+                        escaped);
+        if (r < 0)
+                return r;
+
+        /* After serialization, let's forget the fact that this program is attached. The attachment — if you
+         * so will — is now 'owned' by the serialization, and not us anymore. Why does that matter? Because
+         * of BPF's less-than-ideal lifecycle handling: to detach a program from a cgroup we have to
+         * explicitly do so, it's not done implicitly on close(). Now, since we are serializing here we don't
+         * want the program to be detached while freeing things, so that the attachment can be retained after
+         * deserializing again. bpf_program_free() implicitly detaches things, if attached_path is non-NULL,
+         * hence we set it to NULL here. */
+
+        p->attached_path = mfree(p->attached_path);
+        return 0;
+}
+
+int bpf_program_serialize_attachment_set(FILE *f, FDSet *fds, const char *key, Set *set) {
+        BPFProgram *p;
+        int r;
+
+        SET_FOREACH(p, set) {
+                r = bpf_program_serialize_attachment(f, fds, key, p);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+int bpf_program_deserialize_attachment(const char *v, FDSet *fds, BPFProgram **bpfp) {
+        _cleanup_free_ char *sfd = NULL, *sat = NULL, *unescaped = NULL;
+        _cleanup_(bpf_program_freep) BPFProgram *p = NULL;
+        _cleanup_close_ int fd = -1;
+        ssize_t l;
+        int ifd, at, r;
+
+        assert(v);
+        assert(bpfp);
+
+        /* Extract first word: the fd number */
+        r = extract_first_word(&v, &sfd, NULL, 0);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return -EINVAL;
+
+        r = safe_atoi(sfd, &ifd);
+        if (r < 0)
+                return r;
+        if (ifd < 0)
+                return -EBADF;
+
+        /* Extract second word: the attach type */
+        r = extract_first_word(&v, &sat, NULL, 0);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return -EINVAL;
+
+        at = bpf_cgroup_attach_type_from_string(sat);
+        if (at < 0)
+                return at;
+
+        /* The rest is the path */
+        if (isempty(v))
+                return -EINVAL;
+
+        l = cunescape(v, 0, &unescaped);
+        if (l < 0)
+                return l;
+
+        fd = fdset_remove(fds, ifd);
+        if (fd < 0)
+                return fd;
+
+        p = new(BPFProgram, 1);
+        if (!p)
+                return -ENOMEM;
+
+        *p = (BPFProgram) {
+                .kernel_fd = TAKE_FD(fd),
+                .prog_type = BPF_PROG_TYPE_UNSPEC,
+                .attached_path = TAKE_PTR(unescaped),
+                .attached_type = at,
+        };
+
+        if (*bpfp)
+                bpf_program_free(*bpfp);
+
+        *bpfp = TAKE_PTR(p);
+        return 0;
+}
+
+int bpf_program_deserialize_attachment_set(const char *v, FDSet *fds, Set **bpfsetp) {
+        BPFProgram *p = NULL;
+        int r;
+
+        assert(v);
+        assert(bpfsetp);
+
+        r = bpf_program_deserialize_attachment(v, fds, &p);
+        if (r < 0)
+                return r;
+
+        r = set_ensure_consume(bpfsetp, &bpf_program_hash_ops, p);
+        if (r < 0)
+                return r;
+
+        return 0;
+}