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author | Kyle Evans <kevans@FreeBSD.org> | 2020-04-15 03:59:26 +0000 |
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committer | Kyle Evans <kevans@FreeBSD.org> | 2020-04-15 03:59:26 +0000 |
commit | 142ffb8bdcde64942077c0f9d15936a66aad9725 (patch) | |
tree | 33cdcba9e4cedf3a547fac9ee9a8951e9fc369f2 | |
parent | ddde90ac812b51bd7d73c208fe72415c9b85b263 (diff) | |
download | src-142ffb8bdcde64942077c0f9d15936a66aad9725.tar.gz src-142ffb8bdcde64942077c0f9d15936a66aad9725.zip |
kern uuid: break format validation out into a separate KPI
This new KPI, validate_uuid, strictly validates the formatting of the input
UUID and, optionally, populates a given struct uuid.
As noted in the header, the key differences are that the new KPI won't
recognize an empty string as a nil UUID and it won't do any kind of semantic
validation on it. Also key is that populating a struct uuid is optional, so
the caller doesn't necessarily need to allocate a bogus one on the stack
just to validate the string.
This KPI has specifically been broken out in support of D24288, which will
preload /etc/hostid in loader so that early boot hostuuid users (e.g.
anything that calls ether_gen_addr) can have a valid hostuuid to work with
once it's been stashed in /etc/hostid.
Notes
Notes:
svn path=/head/; revision=359953
-rw-r--r-- | sys/kern/kern_uuid.c | 56 | ||||
-rw-r--r-- | sys/sys/uuid.h | 15 |
2 files changed, 53 insertions, 18 deletions
diff --git a/sys/kern/kern_uuid.c b/sys/kern/kern_uuid.c index ea0877a0cde0..984a2b8cd6ac 100644 --- a/sys/kern/kern_uuid.c +++ b/sys/kern/kern_uuid.c @@ -382,19 +382,16 @@ be_uuid_dec(void const *buf, struct uuid *uuid) } int -parse_uuid(const char *str, struct uuid *uuid) +validate_uuid(const char *str, size_t size, struct uuid *uuid) { u_int c[11]; int n; - /* An empty string represents a nil UUID. */ - if (*str == '\0') { - bzero(uuid, sizeof(*uuid)); - return (0); - } + if (size == 0 || *str == '\0') + return (EINVAL); /* The UUID string representation has a fixed length. */ - if (strlen(str) != 36) + if (size != 36) return (EINVAL); /* @@ -406,25 +403,48 @@ parse_uuid(const char *str, struct uuid *uuid) if (str[8] != '-') return (EINVAL); + /* Now check the format. */ n = sscanf(str, "%8x-%4x-%4x-%2x%2x-%2x%2x%2x%2x%2x%2x", c + 0, c + 1, c + 2, c + 3, c + 4, c + 5, c + 6, c + 7, c + 8, c + 9, c + 10); /* Make sure we have all conversions. */ if (n != 11) return (EINVAL); - /* Successful scan. Build the UUID. */ - uuid->time_low = c[0]; - uuid->time_mid = c[1]; - uuid->time_hi_and_version = c[2]; - uuid->clock_seq_hi_and_reserved = c[3]; - uuid->clock_seq_low = c[4]; - for (n = 0; n < 6; n++) - uuid->node[n] = c[n + 5]; + /* Successful scan. Build the UUID if requested. */ + if (uuid != NULL) { + uuid->time_low = c[0]; + uuid->time_mid = c[1]; + uuid->time_hi_and_version = c[2]; + uuid->clock_seq_hi_and_reserved = c[3]; + uuid->clock_seq_low = c[4]; + for (n = 0; n < 6; n++) + uuid->node[n] = c[n + 5]; + } + + return (0); +} + +int +parse_uuid(const char *str, struct uuid *uuid) +{ + unsigned int clock_seq; + int ret; + + /* An empty string represents a nil UUID. */ + if (*str == '\0') { + bzero(uuid, sizeof(*uuid)); + return (0); + } + + ret = validate_uuid(str, strlen(str), uuid); + if (ret != 0) + return (ret); /* Check semantics... */ - return (((c[3] & 0x80) != 0x00 && /* variant 0? */ - (c[3] & 0xc0) != 0x80 && /* variant 1? */ - (c[3] & 0xe0) != 0xc0) ? EINVAL : 0); /* variant 2? */ + clock_seq = uuid->clock_seq_hi_and_reserved; + return (((clock_seq & 0x80) != 0x00 && /* variant 0? */ + (clock_seq & 0xc0) != 0x80 && /* variant 1? */ + (clock_seq & 0xe0) != 0xc0) ? EINVAL : 0); /* variant 2? */ } int diff --git a/sys/sys/uuid.h b/sys/sys/uuid.h index e60af2180f14..9f0ea3d70fd4 100644 --- a/sys/sys/uuid.h +++ b/sys/sys/uuid.h @@ -66,6 +66,21 @@ int uuid_ether_del(const uint8_t *); int snprintf_uuid(char *, size_t, struct uuid *); int printf_uuid(struct uuid *); int sbuf_printf_uuid(struct sbuf *, struct uuid *); + +/* + * There are a few key differences between validate_uuid and parse_uuid: + * + * - The struct uuid * parameter to validate_uuid is optional, so the caller + * can simply validate UUID format without doing anything with the result. + * - validate_uuid will not pass an empty string as a valid UUID, as it doesn't + * strictly meet the formatting requirements. parse_uuid will accept an + * empty string and zero out the uuid struct accordingly. + * - parse_uuid does additional semantic checks on clock_seq_hi_and_reserved + * that validate_uuid will not do. + * + * validate_uuid is intended to strictly check that it's a well-formed uuid. + */ +int validate_uuid(const char *, size_t, struct uuid *); int parse_uuid(const char *, struct uuid *); int uuidcmp(const struct uuid *, const struct uuid *); |