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Protect base64 encoding buffers #2447

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c402339
tests: characterize extacl base64 stack buffer overflow
kinkie Jun 15, 2026
2125dc5
icap: fix extacl credential buffer overflow in makeRequestHeaders
kinkie Jun 17, 2026
3d1055f
http: fix extacl credential buffer overflows in httpFixupAuthentication
kinkie Jun 17, 2026
1c410dc
Merge remote-tracking branch 'upstream/master' into fix-base64encode
kinkie Jun 19, 2026
f6c053e
Apply aaa
kinkie Jun 20, 2026
ef95154
Remove test harness
kinkie Jun 20, 2026
d7fa149
Use TextException
kinkie Jun 20, 2026
5044dd7
Update src/adaptation/icap/ModXact.cc
kinkie Jul 5, 2026
9c81411
Merge branch 'master' into fix-base64encode
kinkie Jul 7, 2026
c037cd4
define -> constexpr auto
kinkie Jul 7, 2026
8503055
Add field size checks
kinkie Jul 7, 2026
8dff603
Fix Assure() position and include header
kinkie Jul 11, 2026
da6bc4a
Revert broken changes to ModXact.cc
kinkie Jul 11, 2026
987250e
add missing include
kinkie Jul 11, 2026
eb5e533
Accept review suggestion
kinkie Jul 11, 2026
8305b74
add size guard to SSP_MakeChallenge
kinkie Jul 11, 2026
bc1955f
revert BUF_SZ change
kinkie Jul 11, 2026
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12 changes: 9 additions & 3 deletions src/adaptation/icap/ModXact.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1399,12 +1399,18 @@ void Adaptation::Icap::ModXact::makeRequestHeaders(MemBuf &buf)
String vh=virgin.header->header.getById(Http::HdrType::PROXY_AUTHORIZATION);
buf.appendf("Proxy-Authorization: " SQUIDSTRINGPH "\r\n", SQUIDSTRINGPRINT(vh));
} else if (request->extacl_user.size() > 0 && request->extacl_passwd.size() > 0) {
const auto userLen = request->extacl_user.size();
const auto passwdLen = request->extacl_passwd.size();
// +1 for the ':' separator between user and passwd
const auto plainLen = userLen + 1 + passwdLen;
if (plainLen > MAX_LOGIN_SZ)
throw TextException("extacl credentials too long for Proxy-Authorization", Here());
char base64buf[base64_encode_len(MAX_LOGIN_SZ)];
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struct base64_encode_ctx ctx;
base64_encode_init(&ctx);
char base64buf[base64_encode_len(MAX_LOGIN_SZ)];
size_t resultLen = base64_encode_update(&ctx, base64buf, request->extacl_user.size(), reinterpret_cast<const uint8_t*>(request->extacl_user.rawBuf()));
auto resultLen = base64_encode_update(&ctx, base64buf, userLen, reinterpret_cast<const uint8_t*>(request->extacl_user.rawBuf()));
resultLen += base64_encode_update(&ctx, base64buf+resultLen, 1, reinterpret_cast<const uint8_t*>(":"));
resultLen += base64_encode_update(&ctx, base64buf+resultLen, request->extacl_passwd.size(), reinterpret_cast<const uint8_t*>(request->extacl_passwd.rawBuf()));
resultLen += base64_encode_update(&ctx, base64buf+resultLen, passwdLen, reinterpret_cast<const uint8_t*>(request->extacl_passwd.rawBuf()));
resultLen += base64_encode_final(&ctx, base64buf+resultLen);
buf.appendf("Proxy-Authorization: Basic %.*s\r\n", (int)resultLen, base64buf);
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}
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25 changes: 19 additions & 6 deletions src/http.cc
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Expand Up @@ -1850,8 +1850,12 @@ httpFixupAuthentication(HttpRequest * request, const HttpHeader * hdr_in, HttpHe
username = request->auth_user_request->username();
#endif

blen = base64_encode_update(&ctx, loginbuf, strlen(username), reinterpret_cast<const uint8_t*>(username));
blen += base64_encode_update(&ctx, loginbuf+blen, strlen(request->peer_login +1), reinterpret_cast<const uint8_t*>(request->peer_login +1));
const auto usernameLen = strlen(username);
const auto suffixLen = strlen(request->peer_login + 1);
if (usernameLen + suffixLen > MAX_LOGIN_SZ)
throw TextException("peer login credentials too long", Here());
blen = base64_encode_update(&ctx, loginbuf, usernameLen, reinterpret_cast<const uint8_t*>(username));
blen += base64_encode_update(&ctx, loginbuf+blen, suffixLen, reinterpret_cast<const uint8_t*>(request->peer_login +1));
blen += base64_encode_final(&ctx, loginbuf+blen);
httpHeaderPutStrf(hdr_out, header, "Basic %.*s", (int)blen, loginbuf);
return;
Expand All @@ -1862,9 +1866,14 @@ httpFixupAuthentication(HttpRequest * request, const HttpHeader * hdr_in, HttpHe
(strcmp(request->peer_login, "PASS") == 0 ||
strcmp(request->peer_login, "PROXYPASS") == 0)) {

blen = base64_encode_update(&ctx, loginbuf, request->extacl_user.size(), reinterpret_cast<const uint8_t*>(request->extacl_user.rawBuf()));
const auto userLen = request->extacl_user.size();
const auto passwdLen = request->extacl_passwd.size();
// +1 for the ':' separator between user and passwd
if (userLen + 1 + passwdLen > MAX_LOGIN_SZ)
throw TextException("extacl credentials too long for peer login", Here());
blen = base64_encode_update(&ctx, loginbuf, userLen, reinterpret_cast<const uint8_t*>(request->extacl_user.rawBuf()));
blen += base64_encode_update(&ctx, loginbuf+blen, 1, reinterpret_cast<const uint8_t*>(":"));
blen += base64_encode_update(&ctx, loginbuf+blen, request->extacl_passwd.size(), reinterpret_cast<const uint8_t*>(request->extacl_passwd.rawBuf()));
blen += base64_encode_update(&ctx, loginbuf+blen, passwdLen, reinterpret_cast<const uint8_t*>(request->extacl_passwd.rawBuf()));
blen += base64_encode_final(&ctx, loginbuf+blen);
httpHeaderPutStrf(hdr_out, header, "Basic %.*s", (int)blen, loginbuf);
return;
Expand Down Expand Up @@ -1894,7 +1903,10 @@ httpFixupAuthentication(HttpRequest * request, const HttpHeader * hdr_in, HttpHe
}
#endif /* HAVE_KRB5 && HAVE_GSSAPI */

blen = base64_encode_update(&ctx, loginbuf, strlen(request->peer_login), reinterpret_cast<const uint8_t*>(request->peer_login));
const auto loginLen = strlen(request->peer_login);
if (loginLen > MAX_LOGIN_SZ)
throw TextException("peer_login too long", Here());
blen = base64_encode_update(&ctx, loginbuf, loginLen, reinterpret_cast<const uint8_t*>(request->peer_login));
blen += base64_encode_final(&ctx, loginbuf+blen);
httpHeaderPutStrf(hdr_out, header, "Basic %.*s", (int)blen, loginbuf);
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return;
Expand All @@ -1914,13 +1926,14 @@ HttpStateData::httpBuildRequestHeader(HttpRequest * request,
const Http::StateFlags &flags)
{
/* building buffer for complex strings */
#define BBUF_SZ (MAX_URL+32)
constexpr auto BBUF_SZ = MAX_URL + 32;
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LOCAL_ARRAY(char, bbuf, BBUF_SZ);
LOCAL_ARRAY(char, ntoabuf, MAX_IPSTRLEN);
const HttpHeader *hdr_in = &request->header;
const HttpHeaderEntry *e = nullptr;
HttpHeaderPos pos = HttpHeaderInitPos;
assert (hdr_out->owner == hoRequest);
Assure(request->url.userInfo().length() < MAX_URL*2);

@rousskov rousskov Jul 8, 2026

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Please move this assertion much lower, placing it immediately above the base64_encode_update() call.

Rule of thumb: Assert where the invariant is used.

@kinkie kinkie Jul 11, 2026

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done

@rousskov rousskov Jul 12, 2026

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done

Not done (or the changes were not pushed).


/* use our IMS header if the cached entry has Last-Modified time */
if (request->lastmod > -1)
Expand Down
1 change: 1 addition & 0 deletions src/peer_proxy_negotiate_auth.cc
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Expand Up @@ -546,6 +546,7 @@ char *peer_proxy_negotiate_auth(char *principal_name, const char * const proxy,
static char b64buf[8192]; // XXX: 8KB only because base64_encode_bin() used to.
struct base64_encode_ctx ctx;
base64_encode_init(&ctx);
Assure(output_token.length < sizeof(b64buf));
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size_t blen = base64_encode_update(&ctx, b64buf, output_token.length, reinterpret_cast<const uint8_t*>(output_token.value));
blen += base64_encode_final(&ctx, b64buf+blen);
b64buf[blen] = '\0';
Expand Down
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