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Introduce a new utility function smemclr(), which memsets things to

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zero but does it in such a way that over-clever compilers hopefully
won't helpfully optimise the call away if you do it just before
freeing something or letting it go out of scope. Use this for
(hopefully) every memset whose job is to destroy sensitive data that
might otherwise be left lying around in the process's memory.

[originally from svn r9586]
This commit is contained in:
Simon Tatham
2012-07-22 19:51:50 +00:00
parent acf8a5385d
commit aa5bae8916
21 changed files with 140 additions and 89 deletions
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78
import.c
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@ -358,7 +358,7 @@ static struct openssh_key *load_openssh_key(const Filename *filename,
errmsg = "unrecognised key type";
goto error;
}
memset(line, 0, strlen(line));
smemclr(line, strlen(line));
sfree(line);
line = NULL;
@ -442,13 +442,13 @@ static struct openssh_key *load_openssh_key(const Filename *filename,
memcpy(ret->keyblob + ret->keyblob_len, out, len);
ret->keyblob_len += len;
memset(out, 0, sizeof(out));
smemclr(out, sizeof(out));
}
p++;
}
}
memset(line, 0, strlen(line));
smemclr(line, strlen(line));
sfree(line);
line = NULL;
}
@ -463,23 +463,23 @@ static struct openssh_key *load_openssh_key(const Filename *filename,
goto error;
}
memset(base64_bit, 0, sizeof(base64_bit));
smemclr(base64_bit, sizeof(base64_bit));
if (errmsg_p) *errmsg_p = NULL;
return ret;
error:
if (line) {
memset(line, 0, strlen(line));
smemclr(line, strlen(line));
sfree(line);
line = NULL;
}
memset(base64_bit, 0, sizeof(base64_bit));
smemclr(base64_bit, sizeof(base64_bit));
if (ret) {
if (ret->keyblob) {
memset(ret->keyblob, 0, ret->keyblob_size);
smemclr(ret->keyblob, ret->keyblob_size);
sfree(ret->keyblob);
}
memset(ret, 0, sizeof(*ret));
smemclr(ret, sizeof(*ret));
sfree(ret);
}
if (errmsg_p) *errmsg_p = errmsg;
@ -494,9 +494,9 @@ int openssh_encrypted(const Filename *filename)
if (!key)
return 0;
ret = key->encrypted;
memset(key->keyblob, 0, key->keyblob_size);
smemclr(key->keyblob, key->keyblob_size);
sfree(key->keyblob);
memset(key, 0, sizeof(*key));
smemclr(key, sizeof(*key));
sfree(key);
return ret;
}
@ -564,8 +564,8 @@ struct ssh2_userkey *openssh_read(const Filename *filename, char *passphrase,
aes_free_context(ctx);
}
memset(&md5c, 0, sizeof(md5c));
memset(keybuf, 0, sizeof(keybuf));
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
}
/*
@ -698,12 +698,12 @@ struct ssh2_userkey *openssh_read(const Filename *filename, char *passphrase,
error:
if (blob) {
memset(blob, 0, blobsize);
smemclr(blob, blobsize);
sfree(blob);
}
memset(key->keyblob, 0, key->keyblob_size);
smemclr(key->keyblob, key->keyblob_size);
sfree(key->keyblob);
memset(key, 0, sizeof(*key));
smemclr(key, sizeof(*key));
sfree(key);
if (errmsg_p) *errmsg_p = errmsg;
return retval;
@ -911,8 +911,8 @@ int openssh_write(const Filename *filename, struct ssh2_userkey *key,
*/
des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen);
memset(&md5c, 0, sizeof(md5c));
memset(keybuf, 0, sizeof(keybuf));
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
}
/*
@ -936,19 +936,19 @@ int openssh_write(const Filename *filename, struct ssh2_userkey *key,
error:
if (outblob) {
memset(outblob, 0, outlen);
smemclr(outblob, outlen);
sfree(outblob);
}
if (spareblob) {
memset(spareblob, 0, sparelen);
smemclr(spareblob, sparelen);
sfree(spareblob);
}
if (privblob) {
memset(privblob, 0, privlen);
smemclr(privblob, privlen);
sfree(privblob);
}
if (pubblob) {
memset(pubblob, 0, publen);
smemclr(pubblob, publen);
sfree(pubblob);
}
return ret;
@ -1067,7 +1067,7 @@ static struct sshcom_key *load_sshcom_key(const Filename *filename,
errmsg = "file does not begin with ssh.com key header";
goto error;
}
memset(line, 0, strlen(line));
smemclr(line, strlen(line));
sfree(line);
line = NULL;
@ -1112,7 +1112,7 @@ static struct sshcom_key *load_sshcom_key(const Filename *filename,
len += line2len - 1;
assert(!line[len]);
memset(line2, 0, strlen(line2));
smemclr(line2, strlen(line2));
sfree(line2);
line2 = NULL;
}
@ -1158,7 +1158,7 @@ static struct sshcom_key *load_sshcom_key(const Filename *filename,
p++;
}
}
memset(line, 0, strlen(line));
smemclr(line, strlen(line));
sfree(line);
line = NULL;
}
@ -1173,16 +1173,16 @@ static struct sshcom_key *load_sshcom_key(const Filename *filename,
error:
if (line) {
memset(line, 0, strlen(line));
smemclr(line, strlen(line));
sfree(line);
line = NULL;
}
if (ret) {
if (ret->keyblob) {
memset(ret->keyblob, 0, ret->keyblob_size);
smemclr(ret->keyblob, ret->keyblob_size);
sfree(ret->keyblob);
}
memset(ret, 0, sizeof(*ret));
smemclr(ret, sizeof(*ret));
sfree(ret);
}
if (errmsg_p) *errmsg_p = errmsg;
@ -1222,9 +1222,9 @@ int sshcom_encrypted(const Filename *filename, char **comment)
done:
*comment = dupstr(key->comment);
memset(key->keyblob, 0, key->keyblob_size);
smemclr(key->keyblob, key->keyblob_size);
sfree(key->keyblob);
memset(key, 0, sizeof(*key));
smemclr(key, sizeof(*key));
sfree(key);
return answer;
}
@ -1390,8 +1390,8 @@ struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
cipherlen);
memset(&md5c, 0, sizeof(md5c));
memset(keybuf, 0, sizeof(keybuf));
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
/*
* Hereafter we return WRONG_PASSPHRASE for any parsing
@ -1494,12 +1494,12 @@ struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
error:
if (blob) {
memset(blob, 0, blobsize);
smemclr(blob, blobsize);
sfree(blob);
}
memset(key->keyblob, 0, key->keyblob_size);
smemclr(key->keyblob, key->keyblob_size);
sfree(key->keyblob);
memset(key, 0, sizeof(*key));
smemclr(key, sizeof(*key));
sfree(key);
if (errmsg_p) *errmsg_p = errmsg;
return ret;
@ -1664,8 +1664,8 @@ int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
cipherlen);
memset(&md5c, 0, sizeof(md5c));
memset(keybuf, 0, sizeof(keybuf));
smemclr(&md5c, sizeof(md5c));
smemclr(keybuf, sizeof(keybuf));
}
/*
@ -1700,15 +1700,15 @@ int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
error:
if (outblob) {
memset(outblob, 0, outlen);
smemclr(outblob, outlen);
sfree(outblob);
}
if (privblob) {
memset(privblob, 0, privlen);
smemclr(privblob, privlen);
sfree(privblob);
}
if (pubblob) {
memset(pubblob, 0, publen);
smemclr(pubblob, publen);
sfree(pubblob);
}
return ret;