Although not required to address bad code generation in
some versions of gcc 9 and 10, a coding style that requires
explicit comparison of the result to zero before use is
both clearer and would have avoided the generation of bad
code.
This change converts all use of cmp function usage from
```
if (strcmp(a, b) || !strcmp(c, d)) ...
```
to
```
if (strcmp(a, b) != 0 || strcmp(c, d)) == 0
```
for all C library cmp functions and related:
- strcmp(), strncmp()
- strcasecmp(), strncasecmp()
- stricmp(), strnicmp()
- memcmp()
Change-Id: Ic60c15e1e3a07e4faaf10648eefe3adae2543188
As documented in Russell O'Connor's blog, Heimdal when compiled with
some versions of gcc 9 and 10 would generate incorrect behaviors from
_gssapi_verify_mic_arcfour(), _gssapi_unwrap_arcfour(),
_gssapi_unwrap_iov_arcfour() and _gssapi_unwrap_iov_arcfour().
As a result of the bug, code of the form
if (memcmp(a, "\x00\x00\x00\x00"))
and
cmp = memcmp(a, "\x00\x00\x00\x00")
will be compiled as if it were written as
if (strcmp(a, "\x00\x00\x00\x00"))
and
cmp = strcmp(a, "\x00\x00\x00\x00")
but not
if (memcmp(a, "\x00\x00\x00\x00") != 0)
and
cmp = (memcmp(a, "\x00\x00\x00\x00") != 0)
Bad code is generated whenever one of the parameters to memcmp()
is a constant with at least one NUL in the first four octets and
the return value is used immediated without a boolean comparison.
The gcc bug 95189 has since been fixed.
This change applies a defensive programming technique to avoid
the broken code generation.
Change-Id: I1db2a561735317cb6cac66a0ec9caf5443e65e03
Link: https://r6.ca/blog/20200929T023701Z.html
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95189
Reported-by: Buck Huppmann (buckh@pobox.com) <buckh@pobox.com>
ad3acc2aef ("lib/gssapi/krb5:
implement gss_[un]wrap_iov[_length] with arcfour-hmac-md5")
introduced a duplicate block of code.
This change removes the unnecessary code duplication.
Change-Id: I557c590aea51b73dc25d6ce4be4ea84b9dfadd9f
4b543b7 introduced a regression in the krb5 mechanism's gss_unwrap for
DCE applications, owing to IS_DCE_STYLE() being called with a krb5
instead of mechanism context handle.
gss_unwrap_iov() with rc4-hmac (RFC4757) encryption types would fail unless
GSS_C_DCE_STYLE was specified, as an incorrect length was passed to
_gssapi_verify_mech_header(). (The correct length is the header length for
GSS_C_DCE_STYLE, and the wrap token length otherwise.)
RFC 4121/4757 don't require padding as they operate as stream ciphers. Make the
PADDING buffer optional when using these encryption types with gss_wrap_iov()
and gss_unwrap_iov().
a whole krb5_context in TLS. This have some interestion side-effekts
for the configruration setting options since they operate on
per-thread basis now.
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@19031 ec53bebd-3082-4978-b11e-865c3cabbd6b
Stop exposing global gssapi symbols.
Rename gss_context_id_t and gss_cred_id_t to local names.
Remove SPNEGO code, its now in its own gssapi module.
Add mechglue inquire functions.
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@17697 ec53bebd-3082-4978-b11e-865c3cabbd6b
(gss_wrap): set conf_state to conf_req_flags on success
From: Luke Howard <lukeh@PADL.COM>
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@12835 ec53bebd-3082-4978-b11e-865c3cabbd6b
