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Merge branch 'bc/signed-objects-with-both-hashes'

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Signed commits and tags now allow verification of objects, whose
two object names (one in SHA-1, the other in SHA-256) are both
signed.

* bc/signed-objects-with-both-hashes:
  gpg-interface: remove other signature headers before verifying
  ref-filter: hoist signature parsing
  commit: allow parsing arbitrary buffers with headers
  gpg-interface: improve interface for parsing tags
  commit: ignore additional signatures when parsing signed commits
  ref-filter: switch some uses of unsigned long to size_t
This commit is contained in:
Junio C Hamano
2021-02-22 16:12:42 -08:00
parent b9554c03a0 9b27b49240
commit 15af6e6fee
12 changed files with 226 additions and 75 deletions
Download Patch File Download Diff File Expand all files Collapse all files

85
commit.c
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@ -995,7 +995,7 @@ static const char *gpg_sig_headers[] = {
"gpgsig-sha256",
};
static int do_sign_commit(struct strbuf *buf, const char *keyid)
int sign_with_header(struct strbuf *buf, const char *keyid)
{
struct strbuf sig = STRBUF_INIT;
int inspos, copypos;
@ -1035,21 +1035,32 @@ static int do_sign_commit(struct strbuf *buf, const char *keyid)
return 0;
}
int parse_signed_commit(const struct commit *commit,
struct strbuf *payload, struct strbuf *signature)
{
int parse_signed_commit(const struct commit *commit,
struct strbuf *payload, struct strbuf *signature,
const struct git_hash_algo *algop)
{
unsigned long size;
const char *buffer = get_commit_buffer(commit, &size);
int in_signature, saw_signature = -1;
const char *line, *tail;
const char *gpg_sig_header = gpg_sig_headers[hash_algo_by_ptr(the_hash_algo)];
int gpg_sig_header_len = strlen(gpg_sig_header);
int ret = parse_buffer_signed_by_header(buffer, size, payload, signature, algop);
unuse_commit_buffer(commit, buffer);
return ret;
}
int parse_buffer_signed_by_header(const char *buffer,
unsigned long size,
struct strbuf *payload,
struct strbuf *signature,
const struct git_hash_algo *algop)
{
int in_signature = 0, saw_signature = 0, other_signature = 0;
const char *line, *tail, *p;
const char *gpg_sig_header = gpg_sig_headers[hash_algo_by_ptr(algop)];
line = buffer;
tail = buffer + size;
in_signature = 0;
saw_signature = 0;
while (line < tail) {
const char *sig = NULL;
const char *next = memchr(line, '\n', tail - line);
@ -1057,9 +1068,15 @@ int parse_signed_commit(const struct commit *commit,
next = next ? next + 1 : tail;
if (in_signature && line[0] == ' ')
sig = line + 1;
else if (starts_with(line, gpg_sig_header) &&
line[gpg_sig_header_len] == ' ')
sig = line + gpg_sig_header_len + 1;
else if (skip_prefix(line, gpg_sig_header, &p) &&
*p == ' ') {
sig = line + strlen(gpg_sig_header) + 1;
other_signature = 0;
}
else if (starts_with(line, "gpgsig"))
other_signature = 1;
else if (other_signature && line[0] != ' ')
other_signature = 0;
if (sig) {
strbuf_add(signature, sig, next - sig);
saw_signature = 1;
@ -1068,12 +1085,12 @@ int parse_signed_commit(const struct commit *commit,
if (*line == '\n')
/* dump the whole remainder of the buffer */
next = tail;
strbuf_add(payload, line, next - line);
if (!other_signature)
strbuf_add(payload, line, next - line);
in_signature = 0;
}
line = next;
}
unuse_commit_buffer(commit, buffer);
return saw_signature;
}
@ -1082,23 +1099,29 @@ int remove_signature(struct strbuf *buf)
const char *line = buf->buf;
const char *tail = buf->buf + buf->len;
int in_signature = 0;
const char *sig_start = NULL;
const char *sig_end = NULL;
struct sigbuf {
const char *start;
const char *end;
} sigs[2], *sigp = &sigs[0];
int i;
const char *orig_buf = buf->buf;
memset(sigs, 0, sizeof(sigs));
while (line < tail) {
const char *next = memchr(line, '\n', tail - line);
next = next ? next + 1 : tail;
if (in_signature && line[0] == ' ')
sig_end = next;
sigp->end = next;
else if (starts_with(line, "gpgsig")) {
int i;
for (i = 1; i < GIT_HASH_NALGOS; i++) {
const char *p;
if (skip_prefix(line, gpg_sig_headers[i], &p) &&
*p == ' ') {
sig_start = line;
sig_end = next;
sigp->start = line;
sigp->end = next;
in_signature = 1;
}
}
@ -1106,15 +1129,18 @@ int remove_signature(struct strbuf *buf)
if (*line == '\n')
/* dump the whole remainder of the buffer */
next = tail;
if (in_signature && sigp - sigs != ARRAY_SIZE(sigs))
sigp++;
in_signature = 0;
}
line = next;
}
if (sig_start)
strbuf_remove(buf, sig_start - buf->buf, sig_end - sig_start);
for (i = ARRAY_SIZE(sigs) - 1; i >= 0; i--)
if (sigs[i].start)
strbuf_remove(buf, sigs[i].start - orig_buf, sigs[i].end - sigs[i].start);
return sig_start != NULL;
return sigs[0].start != NULL;
}
static void handle_signed_tag(struct commit *parent, struct commit_extra_header ***tail)
@ -1122,8 +1148,10 @@ static void handle_signed_tag(struct commit *parent, struct commit_extra_header
struct merge_remote_desc *desc;
struct commit_extra_header *mergetag;
char *buf;
unsigned long size, len;
unsigned long size;
enum object_type type;
struct strbuf payload = STRBUF_INIT;
struct strbuf signature = STRBUF_INIT;
desc = merge_remote_util(parent);
if (!desc || !desc->obj)
@ -1131,8 +1159,7 @@ static void handle_signed_tag(struct commit *parent, struct commit_extra_header
buf = read_object_file(&desc->obj->oid, &type, &size);
if (!buf || type != OBJ_TAG)
goto free_return;
len = parse_signature(buf, size);
if (size == len)
if (!parse_signature(buf, size, &payload, &signature))
goto free_return;
/*
* We could verify this signature and either omit the tag when
@ -1151,6 +1178,8 @@ static void handle_signed_tag(struct commit *parent, struct commit_extra_header
**tail = mergetag;
*tail = &mergetag->next;
strbuf_release(&payload);
strbuf_release(&signature);
return;
free_return:
@ -1165,7 +1194,7 @@ int check_commit_signature(const struct commit *commit, struct signature_check *
sigc->result = 'N';
if (parse_signed_commit(commit, &payload, &signature) <= 0)
if (parse_signed_commit(commit, &payload, &signature, the_hash_algo) <= 0)
goto out;
ret = check_signature(payload.buf, payload.len, signature.buf,
signature.len, sigc);
@ -1515,7 +1544,7 @@ int commit_tree_extended(const char *msg, size_t msg_len,
if (encoding_is_utf8 && !verify_utf8(&buffer))
fprintf(stderr, _(commit_utf8_warn));
if (sign_commit && do_sign_commit(&buffer, sign_commit)) {
if (sign_commit && sign_with_header(&buffer, sign_commit)) {
result = -1;
goto out;
}