diff options
Diffstat (limited to 'builtin/receive-pack.c')
| -rw-r--r-- | builtin/receive-pack.c | 25 |
1 files changed, 23 insertions, 2 deletions
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c index 2cc18bbffd..239094d2dc 100644 --- a/builtin/receive-pack.c +++ b/builtin/receive-pack.c @@ -13,7 +13,7 @@ #include "remote.h" #include "connect.h" #include "string-list.h" -#include "sha1-array.h" +#include "oid-array.h" #include "connected.h" #include "argv-array.h" #include "version.h" @@ -499,12 +499,27 @@ static char *find_header(const char *msg, size_t len, const char *key, return NULL; } +/* + * Return zero if a and b are equal up to n bytes and nonzero if they are not. + * This operation is guaranteed to run in constant time to avoid leaking data. + */ +static int constant_memequal(const char *a, const char *b, size_t n) +{ + int res = 0; + size_t i; + + for (i = 0; i < n; i++) + res |= a[i] ^ b[i]; + return res; +} + static const char *check_nonce(const char *buf, size_t len) { char *nonce = find_header(buf, len, "nonce", NULL); timestamp_t stamp, ostamp; char *bohmac, *expect = NULL; const char *retval = NONCE_BAD; + size_t noncelen; if (!nonce) { retval = NONCE_MISSING; @@ -546,8 +561,14 @@ static const char *check_nonce(const char *buf, size_t len) goto leave; } + noncelen = strlen(nonce); expect = prepare_push_cert_nonce(service_dir, stamp); - if (strcmp(expect, nonce)) { + if (noncelen != strlen(expect)) { + /* This is not even the right size. */ + retval = NONCE_BAD; + goto leave; + } + if (constant_memequal(expect, nonce, noncelen)) { /* Not what we would have signed earlier */ retval = NONCE_BAD; goto leave; |