Roland Illig wrote:
I updated the patch.
And I updated it once again. There's nothing completely new, just a few
cosmetic changes. The changes are:
- geteuid() is used instead of getuid().
- getegid() is added to the groups[], even if getgroups() fails.
But as it won't fail, there's no effective change.
For the other changes, see the detailed analysis below.
+ if (!initialized) {
+ uid = getuid ();
+ ngroups = getgroups (0, NULL);
+ if (ngroups != -1) {
+ groups = g_new (gid_t, ngroups + 1);
+ ngroups = getgroups (ngroups, groups);
+
+ /* getgroups() may or may not return the effective group ID,
+ * so we always include it at the end of the list. */
+ if (ngroups >= 0) {
+ groups[ngroups++] = getegid();
+ }
+ }
+ initialized = TRUE;
+ }
if (!initialized) {
uid = geteuid ();
-- Here I chose geteuid() instead of getuid(), because it's
-- the effective user ID which is used for the permissions.
ngroups = getgroups (0, NULL);
if (ngroups == -1)
ngroups = 0; /* ignore errors */
-- It is very unlikely that getgroups() fails, and I could have
-- also used assert() for it. But for now, let's just assume
-- we have no additional groups if this call fails.
/* allocate space for one element in addition to what
* will be filled by getgroups(). */
groups = g_new (gid_t, ngroups + 1);
-- Nevertheless, also in the failing case we allocate a GID array,
-- which then will only contain one entry -- the EGID.
if (ngroups != 0) {
-- Make sure getgroups() is not called with ngroups == 0, because
-- otherwise the return value might be > 0.
ngroups = getgroups (ngroups, groups);
-- Here I assume that the value returned by this call will not be
-- greater than the value from the call above. If there is no
-- thread calling setgroups() in between, this should definitely
-- be ok.
if (ngroups == -1)
ngroups = 0; /* ignore errors */
}
-- groups[] has at least ngroups + 1 entries. ngroups of them are
-- filled by getgroups(), and the last one is still free.
/* getgroups() may or may not return the effective group ID,
* so we always include it at the end of the list. */
groups[ngroups++] = getegid ();
initialized = TRUE;
}
Roland
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