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Commit 91d88eeb authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Stephen Hemminger
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{f,m}_bpf: allow updates on program arrays 

Since we have all infrastructure in place now, allow atomic live updates
on program arrays. This can be very useful e.g. in case programs that are
being tail-called need to be replaced, f.e. when classifier functionality
needs to be changed, new protocols added/removed during runtime, etc.

Thus, provide a way for in-place code updates, minimal example: Given is
an object file cls.o that contains the entry point in section 'classifier',
has a globally pinned program array 'jmp' with 2 slots and id of 0, and
two tail called programs under section '0/0' (prog array key 0) and '0/1'
(prog array key 1), the section encoding for the loader is <id/key>.
Adding the filter loads everything into cls_bpf:

  tc filter add dev foo parent ffff: bpf da obj cls.o

Now, the program under section '0/1' needs to be replaced with an updated
version that resides in the same section (also full path to tc's subfolder
of the mount point can be passed, e.g. /sys/fs/bpf/tc/globals/jmp):

  tc exec bpf graft m:globals/jmp obj cls.o sec 0/1

In case the program resides under a different section 'foo', it can also
be injected into the program array like:

  tc exec bpf graft m:globals/jmp key 1 obj cls.o sec foo

If the new tail called classifier program is already available as a pinned
object somewhere (here: /sys/fs/bpf/tc/progs/parser), it can be injected
into the prog array like:

  tc exec bpf graft m:globals/jmp key 1 fd m:progs/parser

In the kernel, the program on key 1 is being atomically replaced and the
old one's refcount dropped.
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent f6793eec
Show whitespace changes
Inline Side-by-side
Showing with 306 additions and 149 deletions
tc/e_bpf.c
View file @ 91d88eeb
......@@ -26,10 +26,19 @@ static char *argv_default[] = { BPF_DEFAULT_CMD, NULL };
static void explain(void)
{
fprintf(stderr, "Usage: ... bpf [ import UDS_FILE ] [ run CMD ] [ debug ]\n\n");
fprintf(stderr, "Usage: ... bpf [ import UDS_FILE ] [ run CMD ]\n");
fprintf(stderr, " ... bpf [ debug ]\n");
fprintf(stderr, " ... bpf [ graft MAP_FILE ] [ key KEY ]\n");
fprintf(stderr, " `... [ object-file OBJ_FILE ] [ type TYPE ] [ section NAME ] [ verbose ]\n");
fprintf(stderr, " `... [ object-pinned PROG_FILE ]\n");
fprintf(stderr, "\n");
fprintf(stderr, "Where UDS_FILE provides the name of a unix domain socket file\n");
fprintf(stderr, "to import eBPF maps and the optional CMD denotes the command\n");
fprintf(stderr, "to be executed (default: \'%s\').\n", BPF_DEFAULT_CMD);
fprintf(stderr, "Where MAP_FILE points to a pinned map, OBJ_FILE to an object file\n");
fprintf(stderr, "and PROG_FILE to a pinned program. TYPE can be {cls, act}, where\n");
fprintf(stderr, "\'cls\' is default. KEY is optional and can be inferred from the\n");
fprintf(stderr, "section name, otherwise it needs to be provided.\n");
}
static int bpf_num_env_entries(void)
......@@ -67,6 +76,25 @@ static int parse_bpf(struct exec_util *eu, int argc, char **argv)
fprintf(stderr,
"No trace pipe, tracefs not mounted?\n");
return -1;
} else if (matches(*argv, "graft") == 0) {
const char *bpf_map_path;
bool has_key = false;
uint32_t key;
NEXT_ARG();
bpf_map_path = *argv;
NEXT_ARG();
if (matches(*argv, "key") == 0) {
NEXT_ARG();
if (get_unsigned(&key, *argv, 0)) {
fprintf(stderr, "Illegal \"key\"\n");
return -1;
}
has_key = true;
NEXT_ARG();
}
return bpf_graft_map(bpf_map_path, has_key ?
&key : NULL, argc, argv);
} else {
explain();
return -1;
......
tc/tc_bpf.c
View file @ 91d88eeb
......@@ -76,13 +76,17 @@ static int bpf(int cmd, union bpf_attr *attr, unsigned int size)
#endif
}
static int bpf_obj_get(const char *pathname)
static int bpf_map_update(int fd, const void *key, const void *value,
uint64_t flags)
{
union bpf_attr attr = {
.pathname = bpf_ptr_to_u64(pathname),
.map_fd = fd,
.key = bpf_ptr_to_u64(key),
.value = bpf_ptr_to_u64(value),
.flags = flags,
};
return bpf(BPF_OBJ_GET, &attr, sizeof(attr));
return bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
}
static int bpf_parse_string(char *arg, bool from_file, __u16 *bpf_len,
......@@ -205,7 +209,8 @@ void bpf_print_ops(FILE *f, struct rtattr *bpf_ops, __u16 len)
ops[i].jf, ops[i].k);
}
static int bpf_map_selfcheck_pinned(int fd, const struct bpf_elf_map *map)
static int bpf_map_selfcheck_pinned(int fd, const struct bpf_elf_map *map,
int length)
{
char file[PATH_MAX], buff[4096];
struct bpf_elf_map tmp, zero;
......@@ -234,7 +239,7 @@ static int bpf_map_selfcheck_pinned(int fd, const struct bpf_elf_map *map)
fclose(fp);
if (!memcmp(&tmp, map, offsetof(struct bpf_elf_map, id))) {
if (!memcmp(&tmp, map, length)) {
return 0;
} else {
memset(&zero, 0, sizeof(zero));
......@@ -243,7 +248,7 @@ static int bpf_map_selfcheck_pinned(int fd, const struct bpf_elf_map *map)
* case, everything is 0. It is guaranteed that no such map exists
* since map type of 0 is unloadable BPF_MAP_TYPE_UNSPEC.
*/
if (!memcmp(&tmp, &zero, offsetof(struct bpf_elf_map, id)))
if (!memcmp(&tmp, &zero, length))
return 0;
fprintf(stderr, "Map specs from pinned file differ!\n");
......@@ -251,6 +256,35 @@ static int bpf_map_selfcheck_pinned(int fd, const struct bpf_elf_map *map)
}
}
static int bpf_mnt_fs(const char *target)
{
bool bind_done = false;
while (mount("", target, "none", MS_PRIVATE | MS_REC, NULL)) {
if (errno != EINVAL || bind_done) {
fprintf(stderr, "mount --make-private %s failed: %s\n",
target, strerror(errno));
return -1;
}
if (mount(target, target, "none", MS_BIND, NULL)) {
fprintf(stderr, "mount --bind %s %s failed: %s\n",
target, target, strerror(errno));
return -1;
}
bind_done = true;
}
if (mount("bpf", target, "bpf", 0, NULL)) {
fprintf(stderr, "mount -t bpf bpf %s failed: %s\n",
target, strerror(errno));
return -1;
}
return 0;
}
static int bpf_valid_mntpt(const char *mnt, unsigned long magic)
{
struct statfs st_fs;
......@@ -342,6 +376,79 @@ int bpf_trace_pipe(void)
return 0;
}
static const char *bpf_get_tc_dir(void)
{
static bool bpf_mnt_cached = false;
static char bpf_tc_dir[PATH_MAX];
static const char *mnt;
static const char * const bpf_known_mnts[] = {
BPF_DIR_MNT,
0,
};
char bpf_mnt[PATH_MAX] = BPF_DIR_MNT;
char bpf_glo_dir[PATH_MAX];
int ret;
if (bpf_mnt_cached)
goto done;
mnt = bpf_find_mntpt("bpf", BPF_FS_MAGIC, bpf_mnt, sizeof(bpf_mnt),
bpf_known_mnts);
if (!mnt) {
mnt = getenv(BPF_ENV_MNT);
if (!mnt)
mnt = BPF_DIR_MNT;
ret = bpf_mnt_fs(mnt);
if (ret) {
mnt = NULL;
goto out;
}
}
snprintf(bpf_tc_dir, sizeof(bpf_tc_dir), "%s/%s", mnt, BPF_DIR_TC);
ret = mkdir(bpf_tc_dir, S_IRWXU);
if (ret && errno != EEXIST) {
fprintf(stderr, "mkdir %s failed: %s\n", bpf_tc_dir,
strerror(errno));
mnt = NULL;
goto out;
}
snprintf(bpf_glo_dir, sizeof(bpf_glo_dir), "%s/%s",
bpf_tc_dir, BPF_DIR_GLOBALS);
ret = mkdir(bpf_glo_dir, S_IRWXU);
if (ret && errno != EEXIST) {
fprintf(stderr, "mkdir %s failed: %s\n", bpf_glo_dir,
strerror(errno));
mnt = NULL;
goto out;
}
mnt = bpf_tc_dir;
out:
bpf_mnt_cached = true;
done:
return mnt;
}
static int bpf_obj_get(const char *pathname)
{
union bpf_attr attr;
char tmp[PATH_MAX];
if (strlen(pathname) > 2 && pathname[0] == 'm' &&
pathname[1] == ':' && bpf_get_tc_dir()) {
snprintf(tmp, sizeof(tmp), "%s/%s",
bpf_get_tc_dir(), pathname + 2);
pathname = tmp;
}
memset(&attr, 0, sizeof(attr));
attr.pathname = bpf_ptr_to_u64(pathname);
return bpf(BPF_OBJ_GET, &attr, sizeof(attr));
}
const char *bpf_default_section(const enum bpf_prog_type type)
{
switch (type) {
......@@ -354,37 +461,45 @@ const char *bpf_default_section(const enum bpf_prog_type type)
}
}
int bpf_parse_common(int *ptr_argc, char ***ptr_argv, const int *nla_tbl,
enum bpf_prog_type type, const char **ptr_object,
const char **ptr_uds_name, struct nlmsghdr *n)
{
struct sock_filter opcodes[BPF_MAXINSNS];
const char *file, *section, *uds_name;
char **argv = *ptr_argv;
int argc = *ptr_argc;
char annotation[256];
bool verbose = false;
int ret;
enum bpf_mode {
CBPF_BYTECODE,
enum bpf_mode {
CBPF_BYTECODE = 0,
CBPF_FILE,
EBPF_OBJECT,
EBPF_PINNED,
} mode;
if (matches(*argv, "bytecode") == 0 ||
strcmp(*argv, "bc") == 0) {
mode = CBPF_BYTECODE;
} else if (matches(*argv, "bytecode-file") == 0 ||
strcmp(*argv, "bcf") == 0) {
mode = CBPF_FILE;
} else if (matches(*argv, "object-file") == 0 ||
strcmp(*argv, "obj") == 0) {
mode = EBPF_OBJECT;
} else if (matches(*argv, "object-pinned") == 0 ||
__BPF_MODE_MAX,
#define BPF_MODE_MAX __BPF_MODE_MAX
};
static int bpf_parse(int *ptr_argc, char ***ptr_argv, const bool *opt_tbl,
enum bpf_prog_type *type, enum bpf_mode *mode,
const char **ptr_object, const char **ptr_section,
const char **ptr_uds_name, struct sock_filter *opcodes)
{
const char *file, *section, *uds_name;
bool verbose = false;
int ret, argc;
char **argv;
argv = *ptr_argv;
argc = *ptr_argc;
if (opt_tbl[CBPF_BYTECODE] &&
(matches(*argv, "bytecode") == 0 ||
strcmp(*argv, "bc") == 0)) {
*mode = CBPF_BYTECODE;
} else if (opt_tbl[CBPF_FILE] &&
(matches(*argv, "bytecode-file") == 0 ||
strcmp(*argv, "bcf") == 0)) {
*mode = CBPF_FILE;
} else if (opt_tbl[EBPF_OBJECT] &&
(matches(*argv, "object-file") == 0 ||
strcmp(*argv, "obj") == 0)) {
*mode = EBPF_OBJECT;
} else if (opt_tbl[EBPF_PINNED] &&
(matches(*argv, "object-pinned") == 0 ||
matches(*argv, "pinned") == 0 ||
matches(*argv, "fd") == 0) {
mode = EBPF_PINNED;
matches(*argv, "fd") == 0)) {
*mode = EBPF_PINNED;
} else {
fprintf(stderr, "What mode is \"%s\"?\n", *argv);
return -1;
......@@ -392,11 +507,29 @@ int bpf_parse_common(int *ptr_argc, char ***ptr_argv, const int *nla_tbl,
NEXT_ARG();
file = section = uds_name = NULL;
if (mode == EBPF_OBJECT || mode == EBPF_PINNED) {
if (*mode == EBPF_OBJECT || *mode == EBPF_PINNED) {
file = *argv;
NEXT_ARG_FWD();
section = bpf_default_section(type);
if (*type == BPF_PROG_TYPE_UNSPEC) {
if (argc > 0 && matches(*argv, "type") == 0) {
NEXT_ARG();
if (matches(*argv, "cls") == 0) {
*type = BPF_PROG_TYPE_SCHED_CLS;
} else if (matches(*argv, "act") == 0) {
*type = BPF_PROG_TYPE_SCHED_ACT;
} else {
fprintf(stderr, "What type is \"%s\"?\n",
*argv);
return -1;
}
NEXT_ARG_FWD();
} else {
*type = BPF_PROG_TYPE_SCHED_CLS;
}
}
section = bpf_default_section(*type);
if (argc > 0 && matches(*argv, "section") == 0) {
NEXT_ARG();
section = *argv;
......@@ -419,35 +552,125 @@ int bpf_parse_common(int *ptr_argc, char ***ptr_argv, const int *nla_tbl,
PREV_ARG();
}
if (mode == CBPF_BYTECODE || mode == CBPF_FILE)
ret = bpf_ops_parse(argc, argv, opcodes, mode == CBPF_FILE);
else if (mode == EBPF_OBJECT)
ret = bpf_obj_open(file, type, section, verbose);
else if (mode == EBPF_PINNED)
if (*mode == CBPF_BYTECODE || *mode == CBPF_FILE)
ret = bpf_ops_parse(argc, argv, opcodes, *mode == CBPF_FILE);
else if (*mode == EBPF_OBJECT)
ret = bpf_obj_open(file, *type, section, verbose);
else if (*mode == EBPF_PINNED)
ret = bpf_obj_get(file);
if (ret < 0)
else
return -1;
if (ptr_object)
*ptr_object = file;
if (ptr_section)
*ptr_section = section;
if (ptr_uds_name)
*ptr_uds_name = uds_name;
*ptr_argc = argc;
*ptr_argv = argv;
return ret;
}
int bpf_parse_common(int *ptr_argc, char ***ptr_argv, const int *nla_tbl,
enum bpf_prog_type type, const char **ptr_object,
const char **ptr_uds_name, struct nlmsghdr *n)
{
struct sock_filter opcodes[BPF_MAXINSNS];
const bool opt_tbl[BPF_MODE_MAX] = {
[CBPF_BYTECODE] = true,
[CBPF_FILE] = true,
[EBPF_OBJECT] = true,
[EBPF_PINNED] = true,
};
char annotation[256];
const char *section;
enum bpf_mode mode;
int ret;
ret = bpf_parse(ptr_argc, ptr_argv, opt_tbl, &type, &mode,
ptr_object, &section, ptr_uds_name, opcodes);
if (ret < 0)
return ret;
if (mode == CBPF_BYTECODE || mode == CBPF_FILE) {
addattr16(n, MAX_MSG, nla_tbl[BPF_NLA_OPS_LEN], ret);
addattr_l(n, MAX_MSG, nla_tbl[BPF_NLA_OPS], opcodes,
ret * sizeof(struct sock_filter));
} else if (mode == EBPF_OBJECT || mode == EBPF_PINNED) {
}
if (mode == EBPF_OBJECT || mode == EBPF_PINNED) {
snprintf(annotation, sizeof(annotation), "%s:[%s]",
basename(file), mode == EBPF_PINNED ? "*fsobj" :
section);
basename(*ptr_object), mode == EBPF_PINNED ?
"*fsobj" : section);
addattr32(n, MAX_MSG, nla_tbl[BPF_NLA_FD], ret);
addattrstrz(n, MAX_MSG, nla_tbl[BPF_NLA_NAME], annotation);
}
*ptr_object = file;
*ptr_uds_name = uds_name;
return 0;
}
*ptr_argc = argc;
*ptr_argv = argv;
int bpf_graft_map(const char *map_path, uint32_t *key, int argc, char **argv)
{
enum bpf_prog_type type = BPF_PROG_TYPE_UNSPEC;
const bool opt_tbl[BPF_MODE_MAX] = {
[CBPF_BYTECODE] = false,
[CBPF_FILE] = false,
[EBPF_OBJECT] = true,
[EBPF_PINNED] = true,
};
const struct bpf_elf_map test = {
.type = BPF_MAP_TYPE_PROG_ARRAY,
.size_key = sizeof(int),
.size_value = sizeof(int),
};
int ret, prog_fd, map_fd;
const char *section;
enum bpf_mode mode;
uint32_t map_key;
prog_fd = bpf_parse(&argc, &argv, opt_tbl, &type, &mode,
NULL, &section, NULL, NULL);
if (prog_fd < 0)
return prog_fd;
if (key) {
map_key = *key;
} else {
ret = sscanf(section, "%*i/%i", &map_key);
if (ret != 1) {
fprintf(stderr, "Couldn\'t infer map key from section "
"name! Please provide \'key\' argument!\n");
ret = -EINVAL;
goto out_prog;
}
}
return 0;
map_fd = bpf_obj_get(map_path);
if (map_fd < 0) {
fprintf(stderr, "Couldn\'t retrieve pinned map \'%s\': %s\n",
map_path, strerror(errno));
ret = map_fd;
goto out_prog;
}
ret = bpf_map_selfcheck_pinned(map_fd, &test,
offsetof(struct bpf_elf_map, max_elem));
if (ret < 0) {
fprintf(stderr, "Map \'%s\' self-check failed!\n", map_path);
goto out_map;
}
ret = bpf_map_update(map_fd, &map_key, &prog_fd, BPF_ANY);
if (ret < 0)
fprintf(stderr, "Map update failed: %s\n", strerror(errno));
out_map:
close(map_fd);
out_prog:
close(prog_fd);
return ret;
}
#ifdef HAVE_ELF
......@@ -530,19 +753,6 @@ static int bpf_map_create(enum bpf_map_type type, unsigned int size_key,
return bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
}
static int bpf_map_update(int fd, const void *key, const void *value,
uint64_t flags)
{
union bpf_attr attr = {
.map_fd = fd,
.key = bpf_ptr_to_u64(key),
.value = bpf_ptr_to_u64(value),
.flags = flags,
};
return bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
}
static int bpf_prog_load(enum bpf_prog_type type, const struct bpf_insn *insns,
size_t size, const char *license)
{
......@@ -672,90 +882,6 @@ done:
return bpf_uid;
}
static int bpf_mnt_fs(const char *target)
{
bool bind_done = false;
while (mount("", target, "none", MS_PRIVATE | MS_REC, NULL)) {
if (errno != EINVAL || bind_done) {
fprintf(stderr, "mount --make-private %s failed: %s\n",
target, strerror(errno));
return -1;
}
if (mount(target, target, "none", MS_BIND, NULL)) {
fprintf(stderr, "mount --bind %s %s failed: %s\n",
target, target, strerror(errno));
return -1;
}
bind_done = true;
}
if (mount("bpf", target, "bpf", 0, NULL)) {
fprintf(stderr, "mount -t bpf bpf %s failed: %s\n",
target, strerror(errno));
return -1;
}
return 0;
}
static const char *bpf_get_tc_dir(void)
{
static bool bpf_mnt_cached = false;
static char bpf_tc_dir[PATH_MAX];
static const char *mnt;
static const char * const bpf_known_mnts[] = {
BPF_DIR_MNT,
0,
};
char bpf_mnt[PATH_MAX] = BPF_DIR_MNT;
char bpf_glo_dir[PATH_MAX];
int ret;
if (bpf_mnt_cached)
goto done;
mnt = bpf_find_mntpt("bpf", BPF_FS_MAGIC, bpf_mnt, sizeof(bpf_mnt),
bpf_known_mnts);
if (!mnt) {
mnt = getenv(BPF_ENV_MNT);
if (!mnt)
mnt = BPF_DIR_MNT;
ret = bpf_mnt_fs(mnt);
if (ret) {
mnt = NULL;
goto out;
}
}
snprintf(bpf_tc_dir, sizeof(bpf_tc_dir), "%s/%s", mnt, BPF_DIR_TC);
ret = mkdir(bpf_tc_dir, S_IRWXU);
if (ret && errno != EEXIST) {
fprintf(stderr, "mkdir %s failed: %s\n", bpf_tc_dir,
strerror(errno));
mnt = NULL;
goto out;
}
snprintf(bpf_glo_dir, sizeof(bpf_glo_dir), "%s/%s",
bpf_tc_dir, BPF_DIR_GLOBALS);
ret = mkdir(bpf_glo_dir, S_IRWXU);
if (ret && errno != EEXIST) {
fprintf(stderr, "mkdir %s failed: %s\n", bpf_glo_dir,
strerror(errno));
mnt = NULL;
goto out;
}
mnt = bpf_tc_dir;
out:
bpf_mnt_cached = true;
done:
return mnt;
}
static int bpf_init_env(const char *pathname)
{
struct rlimit limit = {
......@@ -931,7 +1057,9 @@ static int bpf_map_attach(const char *name, const struct bpf_elf_map *map,
fd = bpf_probe_pinned(name, ctx, map->pinning);
if (fd > 0) {
ret = bpf_map_selfcheck_pinned(fd, map);
ret = bpf_map_selfcheck_pinned(fd, map,
offsetof(struct bpf_elf_map,
id));
if (ret < 0) {
close(fd);
fprintf(stderr, "Map \'%s\' self-check failed!\n",
......
tc/tc_bpf.h
View file @ 91d88eeb
......@@ -55,6 +55,7 @@ const char *bpf_default_section(const enum bpf_prog_type type);
int bpf_parse_common(int *ptr_argc, char ***ptr_argv, const int *nla_tbl,
enum bpf_prog_type type, const char **ptr_object,
const char **ptr_uds_name, struct nlmsghdr *n);
int bpf_graft_map(const char *map_path, uint32_t *key, int argc, char **argv);
void bpf_print_ops(FILE *f, struct rtattr *bpf_ops, __u16 len);
......
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