diff options
Diffstat (limited to 'src/libsystemd/sd-id128')
| -rw-r--r-- | src/libsystemd/sd-id128/id128-util.c | 193 | ||||
| -rw-r--r-- | src/libsystemd/sd-id128/id128-util.h | 33 | ||||
| -rw-r--r-- | src/libsystemd/sd-id128/sd-id128.c | 340 |
3 files changed, 566 insertions, 0 deletions
diff --git a/src/libsystemd/sd-id128/id128-util.c b/src/libsystemd/sd-id128/id128-util.c new file mode 100644 index 0000000..9ffd594 --- /dev/null +++ b/src/libsystemd/sd-id128/id128-util.c @@ -0,0 +1,193 @@ +/* SPDX-License-Identifier: LGPL-2.1+ */ + +#include <errno.h> +#include <fcntl.h> +#include <unistd.h> + +#include "fd-util.h" +#include "fs-util.h" +#include "hexdecoct.h" +#include "id128-util.h" +#include "io-util.h" +#include "stdio-util.h" + +char *id128_to_uuid_string(sd_id128_t id, char s[37]) { + unsigned n, k = 0; + + assert(s); + + /* Similar to sd_id128_to_string() but formats the result as UUID instead of plain hex chars */ + + for (n = 0; n < 16; n++) { + + if (IN_SET(n, 4, 6, 8, 10)) + s[k++] = '-'; + + s[k++] = hexchar(id.bytes[n] >> 4); + s[k++] = hexchar(id.bytes[n] & 0xF); + } + + assert(k == 36); + + s[k] = 0; + + return s; +} + +bool id128_is_valid(const char *s) { + size_t i, l; + + assert(s); + + l = strlen(s); + if (l == 32) { + + /* Plain formatted 128bit hex string */ + + for (i = 0; i < l; i++) { + char c = s[i]; + + if (!(c >= '0' && c <= '9') && + !(c >= 'a' && c <= 'z') && + !(c >= 'A' && c <= 'Z')) + return false; + } + + } else if (l == 36) { + + /* Formatted UUID */ + + for (i = 0; i < l; i++) { + char c = s[i]; + + if (IN_SET(i, 8, 13, 18, 23)) { + if (c != '-') + return false; + } else { + if (!(c >= '0' && c <= '9') && + !(c >= 'a' && c <= 'z') && + !(c >= 'A' && c <= 'Z')) + return false; + } + } + + } else + return false; + + return true; +} + +int id128_read_fd(int fd, Id128Format f, sd_id128_t *ret) { + char buffer[36 + 2]; + ssize_t l; + + assert(fd >= 0); + assert(f < _ID128_FORMAT_MAX); + + /* Reads an 128bit ID from a file, which may either be in plain format (32 hex digits), or in UUID format, both + * optionally followed by a newline and nothing else. ID files should really be newline terminated, but if they + * aren't that's OK too, following the rule of "Be conservative in what you send, be liberal in what you + * accept". */ + + l = loop_read(fd, buffer, sizeof(buffer), false); /* we expect a short read of either 32/33 or 36/37 chars */ + if (l < 0) + return (int) l; + if (l == 0) /* empty? */ + return -ENOMEDIUM; + + switch (l) { + + case 33: /* plain UUID with trailing newline */ + if (buffer[32] != '\n') + return -EINVAL; + + _fallthrough_; + case 32: /* plain UUID without trailing newline */ + if (f == ID128_UUID) + return -EINVAL; + + buffer[32] = 0; + break; + + case 37: /* RFC UUID with trailing newline */ + if (buffer[36] != '\n') + return -EINVAL; + + _fallthrough_; + case 36: /* RFC UUID without trailing newline */ + if (f == ID128_PLAIN) + return -EINVAL; + + buffer[36] = 0; + break; + + default: + return -EINVAL; + } + + return sd_id128_from_string(buffer, ret); +} + +int id128_read(const char *p, Id128Format f, sd_id128_t *ret) { + _cleanup_close_ int fd = -1; + + fd = open(p, O_RDONLY|O_CLOEXEC|O_NOCTTY); + if (fd < 0) + return -errno; + + return id128_read_fd(fd, f, ret); +} + +int id128_write_fd(int fd, Id128Format f, sd_id128_t id, bool do_sync) { + char buffer[36 + 2]; + size_t sz; + int r; + + assert(fd >= 0); + assert(f < _ID128_FORMAT_MAX); + + if (f != ID128_UUID) { + sd_id128_to_string(id, buffer); + buffer[32] = '\n'; + sz = 33; + } else { + id128_to_uuid_string(id, buffer); + buffer[36] = '\n'; + sz = 37; + } + + r = loop_write(fd, buffer, sz, false); + if (r < 0) + return r; + + if (do_sync) { + if (fsync(fd) < 0) + return -errno; + + r = fsync_directory_of_file(fd); + if (r < 0) + return r; + } + + return 0; +} + +int id128_write(const char *p, Id128Format f, sd_id128_t id, bool do_sync) { + _cleanup_close_ int fd = -1; + + fd = open(p, O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY|O_TRUNC, 0444); + if (fd < 0) + return -errno; + + return id128_write_fd(fd, f, id, do_sync); +} + +void id128_hash_func(const sd_id128_t *p, struct siphash *state) { + siphash24_compress(p, sizeof(sd_id128_t), state); +} + +int id128_compare_func(const sd_id128_t *a, const sd_id128_t *b) { + return memcmp(a, b, 16); +} + +DEFINE_HASH_OPS(id128_hash_ops, sd_id128_t, id128_hash_func, id128_compare_func); diff --git a/src/libsystemd/sd-id128/id128-util.h b/src/libsystemd/sd-id128/id128-util.h new file mode 100644 index 0000000..65f14ab --- /dev/null +++ b/src/libsystemd/sd-id128/id128-util.h @@ -0,0 +1,33 @@ +/* SPDX-License-Identifier: LGPL-2.1+ */ +#pragma once + +#include <stdbool.h> + +#include "sd-id128.h" + +#include "hash-funcs.h" +#include "macro.h" + +char *id128_to_uuid_string(sd_id128_t id, char s[37]); + +/* Like SD_ID128_FORMAT_STR, but formats as UUID, not in plain format */ +#define ID128_UUID_FORMAT_STR "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x" + +bool id128_is_valid(const char *s) _pure_; + +typedef enum Id128Format { + ID128_ANY, + ID128_PLAIN, /* formatted as 32 hex chars as-is */ + ID128_UUID, /* formatted as 36 character uuid string */ + _ID128_FORMAT_MAX, +} Id128Format; + +int id128_read_fd(int fd, Id128Format f, sd_id128_t *ret); +int id128_read(const char *p, Id128Format f, sd_id128_t *ret); + +int id128_write_fd(int fd, Id128Format f, sd_id128_t id, bool do_sync); +int id128_write(const char *p, Id128Format f, sd_id128_t id, bool do_sync); + +void id128_hash_func(const sd_id128_t *p, struct siphash *state); +int id128_compare_func(const sd_id128_t *a, const sd_id128_t *b) _pure_; +extern const struct hash_ops id128_hash_ops; diff --git a/src/libsystemd/sd-id128/sd-id128.c b/src/libsystemd/sd-id128/sd-id128.c new file mode 100644 index 0000000..e72af15 --- /dev/null +++ b/src/libsystemd/sd-id128/sd-id128.c @@ -0,0 +1,340 @@ +/* SPDX-License-Identifier: LGPL-2.1+ */ + +#include <errno.h> +#include <fcntl.h> +#include <unistd.h> + +#include "sd-id128.h" + +#include "alloc-util.h" +#include "fd-util.h" +#include "hexdecoct.h" +#include "id128-util.h" +#include "io-util.h" +#include "khash.h" +#include "macro.h" +#include "missing.h" +#include "random-util.h" +#include "user-util.h" +#include "util.h" + +_public_ char *sd_id128_to_string(sd_id128_t id, char s[_SD_ARRAY_STATIC SD_ID128_STRING_MAX]) { + unsigned n; + + assert_return(s, NULL); + + for (n = 0; n < 16; n++) { + s[n*2] = hexchar(id.bytes[n] >> 4); + s[n*2+1] = hexchar(id.bytes[n] & 0xF); + } + + s[32] = 0; + + return s; +} + +_public_ int sd_id128_from_string(const char s[], sd_id128_t *ret) { + unsigned n, i; + sd_id128_t t; + bool is_guid = false; + + assert_return(s, -EINVAL); + + for (n = 0, i = 0; n < 16;) { + int a, b; + + if (s[i] == '-') { + /* Is this a GUID? Then be nice, and skip over + * the dashes */ + + if (i == 8) + is_guid = true; + else if (IN_SET(i, 13, 18, 23)) { + if (!is_guid) + return -EINVAL; + } else + return -EINVAL; + + i++; + continue; + } + + a = unhexchar(s[i++]); + if (a < 0) + return -EINVAL; + + b = unhexchar(s[i++]); + if (b < 0) + return -EINVAL; + + t.bytes[n++] = (a << 4) | b; + } + + if (i != (is_guid ? 36 : 32)) + return -EINVAL; + + if (s[i] != 0) + return -EINVAL; + + if (ret) + *ret = t; + return 0; +} + +_public_ int sd_id128_get_machine(sd_id128_t *ret) { + static thread_local sd_id128_t saved_machine_id = {}; + int r; + + assert_return(ret, -EINVAL); + + if (sd_id128_is_null(saved_machine_id)) { + r = id128_read("/etc/machine-id", ID128_PLAIN, &saved_machine_id); + if (r < 0) + return r; + + if (sd_id128_is_null(saved_machine_id)) + return -ENOMEDIUM; + } + + *ret = saved_machine_id; + return 0; +} + +_public_ int sd_id128_get_boot(sd_id128_t *ret) { + static thread_local sd_id128_t saved_boot_id = {}; + int r; + + assert_return(ret, -EINVAL); + + if (sd_id128_is_null(saved_boot_id)) { + r = id128_read("/proc/sys/kernel/random/boot_id", ID128_UUID, &saved_boot_id); + if (r < 0) + return r; + } + + *ret = saved_boot_id; + return 0; +} + +static int get_invocation_from_keyring(sd_id128_t *ret) { + + _cleanup_free_ char *description = NULL; + char *d, *p, *g, *u, *e; + unsigned long perms; + key_serial_t key; + size_t sz = 256; + uid_t uid; + gid_t gid; + int r, c; + +#define MAX_PERMS ((unsigned long) (KEY_POS_VIEW|KEY_POS_READ|KEY_POS_SEARCH| \ + KEY_USR_VIEW|KEY_USR_READ|KEY_USR_SEARCH)) + + assert(ret); + + key = request_key("user", "invocation_id", NULL, 0); + if (key == -1) { + /* Keyring support not available? No invocation key stored? */ + if (IN_SET(errno, ENOSYS, ENOKEY)) + return 0; + + return -errno; + } + + for (;;) { + description = new(char, sz); + if (!description) + return -ENOMEM; + + c = keyctl(KEYCTL_DESCRIBE, key, (unsigned long) description, sz, 0); + if (c < 0) + return -errno; + + if ((size_t) c <= sz) + break; + + sz = c; + free(description); + } + + /* The kernel returns a final NUL in the string, verify that. */ + assert(description[c-1] == 0); + + /* Chop off the final description string */ + d = strrchr(description, ';'); + if (!d) + return -EIO; + *d = 0; + + /* Look for the permissions */ + p = strrchr(description, ';'); + if (!p) + return -EIO; + + errno = 0; + perms = strtoul(p + 1, &e, 16); + if (errno > 0) + return -errno; + if (e == p + 1) /* Read at least one character */ + return -EIO; + if (e != d) /* Must reached the end */ + return -EIO; + + if ((perms & ~MAX_PERMS) != 0) + return -EPERM; + + *p = 0; + + /* Look for the group ID */ + g = strrchr(description, ';'); + if (!g) + return -EIO; + r = parse_gid(g + 1, &gid); + if (r < 0) + return r; + if (gid != 0) + return -EPERM; + *g = 0; + + /* Look for the user ID */ + u = strrchr(description, ';'); + if (!u) + return -EIO; + r = parse_uid(u + 1, &uid); + if (r < 0) + return r; + if (uid != 0) + return -EPERM; + + c = keyctl(KEYCTL_READ, key, (unsigned long) ret, sizeof(sd_id128_t), 0); + if (c < 0) + return -errno; + if (c != sizeof(sd_id128_t)) + return -EIO; + + return 1; +} + +_public_ int sd_id128_get_invocation(sd_id128_t *ret) { + static thread_local sd_id128_t saved_invocation_id = {}; + int r; + + assert_return(ret, -EINVAL); + + if (sd_id128_is_null(saved_invocation_id)) { + + /* We first try to read the invocation ID from the kernel keyring. This has the benefit that it is not + * fakeable by unprivileged code. If the information is not available in the keyring, we use + * $INVOCATION_ID but ignore the data if our process was called by less privileged code + * (i.e. secure_getenv() instead of getenv()). + * + * The kernel keyring is only relevant for system services (as for user services we don't store the + * invocation ID in the keyring, as there'd be no trust benefit in that). The environment variable is + * primarily relevant for user services, and sufficiently safe as no privilege boundary is involved. */ + + r = get_invocation_from_keyring(&saved_invocation_id); + if (r < 0) + return r; + + if (r == 0) { + const char *e; + + e = secure_getenv("INVOCATION_ID"); + if (!e) + return -ENXIO; + + r = sd_id128_from_string(e, &saved_invocation_id); + if (r < 0) + return r; + } + } + + *ret = saved_invocation_id; + return 0; +} + +static sd_id128_t make_v4_uuid(sd_id128_t id) { + /* Stolen from generate_random_uuid() of drivers/char/random.c + * in the kernel sources */ + + /* Set UUID version to 4 --- truly random generation */ + id.bytes[6] = (id.bytes[6] & 0x0F) | 0x40; + + /* Set the UUID variant to DCE */ + id.bytes[8] = (id.bytes[8] & 0x3F) | 0x80; + + return id; +} + +_public_ int sd_id128_randomize(sd_id128_t *ret) { + sd_id128_t t; + int r; + + assert_return(ret, -EINVAL); + + /* We allow usage if x86-64 RDRAND here. It might not be trusted enough for keeping secrets, but it should be + * fine for UUIDS. */ + r = genuine_random_bytes(&t, sizeof t, RANDOM_ALLOW_RDRAND); + if (r < 0) + return r; + + /* Turn this into a valid v4 UUID, to be nice. Note that we + * only guarantee this for newly generated UUIDs, not for + * pre-existing ones. */ + + *ret = make_v4_uuid(t); + return 0; +} + +static int get_app_specific(sd_id128_t base, sd_id128_t app_id, sd_id128_t *ret) { + _cleanup_(khash_unrefp) khash *h = NULL; + sd_id128_t result; + const void *p; + int r; + + assert(ret); + + r = khash_new_with_key(&h, "hmac(sha256)", &base, sizeof(base)); + if (r < 0) + return r; + + r = khash_put(h, &app_id, sizeof(app_id)); + if (r < 0) + return r; + + r = khash_digest_data(h, &p); + if (r < 0) + return r; + + /* We chop off the trailing 16 bytes */ + memcpy(&result, p, MIN(khash_get_size(h), sizeof(result))); + + *ret = make_v4_uuid(result); + return 0; +} + +_public_ int sd_id128_get_machine_app_specific(sd_id128_t app_id, sd_id128_t *ret) { + sd_id128_t id; + int r; + + assert_return(ret, -EINVAL); + + r = sd_id128_get_machine(&id); + if (r < 0) + return r; + + return get_app_specific(id, app_id, ret); +} + +_public_ int sd_id128_get_boot_app_specific(sd_id128_t app_id, sd_id128_t *ret) { + sd_id128_t id; + int r; + + assert_return(ret, -EINVAL); + + r = sd_id128_get_boot(&id); + if (r < 0) + return r; + + return get_app_specific(id, app_id, ret); +} |