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dropbearkey: save a public key file .pub #267

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merged 3 commits into from
Jan 22, 2024
Merged

dropbearkey: save a public key file .pub #267

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b51e1fa
dropbearkey: -C option to specify a comment/email for the generated key
stokito Dec 16, 2023
efb106c
dropbearkey: save a public key file on a key generation
stokito Dec 16, 2023
44b611f
Use fprintf rather than dprintf to write pubkey
mkj Jan 22, 2024
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95 changes: 76 additions & 19 deletions src/dropbearkey.c
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Original file line number Diff line number Diff line change
Expand Up @@ -63,9 +63,12 @@

static void printhelp(char * progname);


static void printpubkey(sign_key * key, int keytype);
static int printpubfile(const char* filename);
static void printpubkey(sign_key * key, int keytype, const char * comment, int create_pub_file, const char * filename);
/* Print a public key and fingerprint to stdout.
* Used for "dropbearkey -y" command but also after generation of a new key.
* For the new key pair the create_pub_file will be TRUE and the pub key will be saved to a .pub file.
*/
static int printpubfile(const char* filename, const char * comment, int create_pub_file);

/* Print a help message */
static void printhelp(char * progname) {
Expand Down Expand Up @@ -107,6 +110,7 @@ static void printhelp(char * progname) {
" Ed25519 has a fixed size of 256 bits\n"
#endif
"-y Just print the publickey and fingerprint for the\n private key in <filename>.\n"
"-C Specify the key comment (email).\n"
#if DEBUG_TRACE
"-v verbose\n"
#endif
Expand Down Expand Up @@ -160,6 +164,7 @@ int main(int argc, char ** argv) {
char * typetext = NULL;
char * sizetext = NULL;
char * passphrase = NULL;
char * comment = NULL;
unsigned int bits = 0, genbits;
int printpub = 0;

Expand Down Expand Up @@ -188,6 +193,9 @@ int main(int argc, char ** argv) {
case 's':
next = &sizetext;
break;
case 'C':
next = &comment;
break;
case 'y':
printpub = 1;
break;
Expand Down Expand Up @@ -221,7 +229,7 @@ int main(int argc, char ** argv) {
}

if (printpub) {
int ret = printpubfile(filename);
int ret = printpubfile(filename, NULL, 0);
exit(ret);
}

Expand Down Expand Up @@ -284,13 +292,13 @@ int main(int argc, char ** argv) {
dropbear_exit("Failed to generate key.\n");
}

printpubfile(filename);
printpubfile(filename, comment, 1);

return EXIT_SUCCESS;
}
#endif

static int printpubfile(const char* filename) {
static int printpubfile(const char* filename, const char* comment, int create_pub_file) {

buffer *buf = NULL;
sign_key *key = NULL;
Expand All @@ -316,7 +324,7 @@ static int printpubfile(const char* filename) {
goto out;
}

printpubkey(key, keytype);
printpubkey(key, keytype, comment, create_pub_file, filename);

err = DROPBEAR_SUCCESS;

Expand All @@ -330,7 +338,7 @@ static int printpubfile(const char* filename) {
return err;
}

static void printpubkey(sign_key * key, int keytype) {
static void printpubkey(sign_key * key, int keytype, const char * comment, int create_pub_file, const char * filename) {

buffer * buf = NULL;
unsigned char base64key[MAX_PUBKEY_SIZE*2];
Expand All @@ -342,6 +350,31 @@ static void printpubkey(sign_key * key, int keytype) {
struct passwd * pw = NULL;
char * username = NULL;
char hostname[100];
char * filename_pub = NULL;
FILE *pubkey_file = NULL;

if (create_pub_file) {
int pubkey_fd = -1;
int filename_pub_len = 0;
filename_pub_len = strlen(filename) + 5;
filename_pub = m_malloc(filename_pub_len);
snprintf(filename_pub, filename_pub_len, "%s.pub", filename);

/* open() to use O_EXCL, then use a FILE* for fprintf().
* dprintf() is only posix2008 onwards */
pubkey_fd = open(filename_pub, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
if (pubkey_fd >= 0) {
/* Convert the fd to a FILE*. The underlying FD is closed
* by later fclose() */
pubkey_file = fdopen(pubkey_fd, "w");
if (!pubkey_file) {
m_close(pubkey_fd);
}
}
if (!pubkey_file) {
dropbear_log(LOG_ERR, "Save public key to %s failed: %s", filename_pub, strerror(errno));
}
}

buf = buf_new(MAX_PUBKEY_SIZE);
buf_put_pub_key(buf, key, keytype);
Expand All @@ -358,21 +391,45 @@ static void printpubkey(sign_key * key, int keytype) {

typestring = signkey_name_from_type(keytype, NULL);

fp = sign_key_fingerprint(buf_getptr(buf, len), len);
printf("Public key portion is:\n");

/* a user@host comment is informative */
username = "";
pw = getpwuid(getuid());
if (pw) {
username = pw->pw_name;
}
if (comment) {
printf("%s %s %s\n",
typestring, base64key, comment);
if (pubkey_file) {
fprintf(pubkey_file, "%s %s %s\n",
typestring, base64key, comment);
}
} else {
/* a user@host comment is informative */
username = "";
pw = getpwuid(getuid());
if (pw) {
username = pw->pw_name;
}

gethostname(hostname, sizeof(hostname));
hostname[sizeof(hostname) - 1] = '\0';

gethostname(hostname, sizeof(hostname));
hostname[sizeof(hostname)-1] = '\0';
printf("%s %s %s@%s\n",
typestring, base64key, username, hostname);
if (pubkey_file) {
fprintf(pubkey_file, "%s %s %s@%s\n",
typestring, base64key, username, hostname);
}
}

printf("Public key portion is:\n%s %s %s@%s\nFingerprint: %s\n",
typestring, base64key, username, hostname, fp);
fp = sign_key_fingerprint(buf_getptr(buf, len), len);
printf("Fingerprint: %s\n", fp);

m_free(fp);
buf_free(buf);
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if (pubkey_file) {
if (fsync(fileno(pubkey_file)) != 0) {
dropbear_log(LOG_ERR, "fsync of %s failed: %s", filename_pub, strerror(errno));
}
fclose(pubkey_file);
}
m_free(filename_pub);
}