+static enum {
+ PRIV_DROPPING, PRIV_DROPPED,
+ PRIV_RESTORING, PRIV_RESTORED
+} priv_state = PRIV_RESTORED;
+
+static uid_t priv_euid;
+static gid_t priv_egid;
+static gid_t priv_groups[EXIM_GROUPLIST_SIZE + 1];
+static int priv_ngroups;
+
+/* Inspired by OpenSSH's temporarily_use_uid(). Thanks! */
+
+static void
+priv_drop_temp(const uid_t temp_uid, const gid_t temp_gid)
+{
+if (priv_state != PRIV_RESTORED) _exit(EXIT_FAILURE);
+priv_state = PRIV_DROPPING;
+
+priv_euid = geteuid();
+if (priv_euid == root_uid)
+ {
+ priv_egid = getegid();
+ priv_ngroups = getgroups(nelem(priv_groups), priv_groups);
+ if (priv_ngroups < 0) _exit(EXIT_FAILURE);
+
+ if (priv_ngroups > 0 && setgroups(1, &temp_gid) != 0) _exit(EXIT_FAILURE);
+ if (setegid(temp_gid) != 0) _exit(EXIT_FAILURE);
+ if (seteuid(temp_uid) != 0) _exit(EXIT_FAILURE);
+
+ if (geteuid() != temp_uid) _exit(EXIT_FAILURE);
+ if (getegid() != temp_gid) _exit(EXIT_FAILURE);
+ }
+
+priv_state = PRIV_DROPPED;
+}
+
+/* Inspired by OpenSSH's restore_uid(). Thanks! */
+
+static void
+priv_restore(void)
+{
+if (priv_state != PRIV_DROPPED) _exit(EXIT_FAILURE);
+priv_state = PRIV_RESTORING;
+
+if (priv_euid == root_uid)
+ {
+ if (seteuid(priv_euid) != 0) _exit(EXIT_FAILURE);
+ if (setegid(priv_egid) != 0) _exit(EXIT_FAILURE);
+ if (priv_ngroups > 0 && setgroups(priv_ngroups, priv_groups) != 0) _exit(EXIT_FAILURE);
+
+ if (geteuid() != priv_euid) _exit(EXIT_FAILURE);
+ if (getegid() != priv_egid) _exit(EXIT_FAILURE);
+ }
+
+priv_state = PRIV_RESTORED;
+}
+
+
+
+
/*************************************************
* Open and lock a database file *
*************************************************/
{
int rc, save_errno;
BOOL read_only = flags == O_RDONLY;
-BOOL created = FALSE;
flock_t lock_data;
uschar dirname[256], filename[256];
snprintf(CS dirname, sizeof(dirname), "%s/db", spool_directory);
snprintf(CS filename, sizeof(filename), "%s/%s.lockfile", dirname, name);
+priv_drop_temp(exim_uid, exim_gid);
if ((dbblock->lockfd = Uopen(filename, O_RDWR, EXIMDB_LOCKFILE_MODE)) < 0)
{
- created = TRUE;
(void)directory_make(spool_directory, US"db", EXIMDB_DIRECTORY_MODE, panic);
dbblock->lockfd = Uopen(filename, O_RDWR|O_CREAT, EXIMDB_LOCKFILE_MODE);
}
+priv_restore();
if (dbblock->lockfd < 0)
{
open call. */
snprintf(CS filename, sizeof(filename), "%s/%s", dirname, name);
-EXIM_DBOPEN(filename, dirname, flags, EXIMDB_MODE, &(dbblock->dbptr));
+priv_drop_temp(exim_uid, exim_gid);
+EXIM_DBOPEN(filename, dirname, flags, EXIMDB_MODE, &(dbblock->dbptr));
if (!dbblock->dbptr && errno == ENOENT && flags == O_RDWR)
{
DEBUG(D_hints_lookup)
debug_printf_indent("%s appears not to exist: trying to create\n", filename);
- created = TRUE;
EXIM_DBOPEN(filename, dirname, flags|O_CREAT, EXIMDB_MODE, &(dbblock->dbptr));
}
-
save_errno = errno;
-
-/* If we are running as root and this is the first access to the database, its
-files will be owned by root. We want them to be owned by exim. We detect this
-situation by noting above when we had to create the lock file or the database
-itself. Because the different dbm libraries use different extensions for their
-files, I don't know of any easier way of arranging this than scanning the
-directory for files with the appropriate base name. At least this deals with
-the lock file at the same time. Also, the directory will typically have only
-half a dozen files, so the scan will be quick.
-
-This code is placed here, before the test for successful opening, because there
-was a case when a file was created, but the DBM library still returned NULL
-because of some problem. It also sorts out the lock file if that was created
-but creation of the database file failed. */
-
-if (created && geteuid() == root_uid)
- {
- DIR * dd;
- uschar *lastname = Ustrrchr(filename, '/') + 1;
- int namelen = Ustrlen(name);
-
- *lastname = 0;
-
- if ((dd = exim_opendir(filename)))
- for (struct dirent *ent; ent = readdir(dd); )
- if (Ustrncmp(ent->d_name, name, namelen) == 0)
- {
- struct stat statbuf;
- /* Filenames from readdir() are trusted,
- so use a taint-nonchecking copy */
- strcpy(CS lastname, CCS ent->d_name);
- if (Ustat(filename, &statbuf) >= 0 && statbuf.st_uid != exim_uid)
- {
- DEBUG(D_hints_lookup)
- debug_printf_indent("ensuring %s is owned by exim\n", filename);
- if (exim_chown(filename, exim_uid, exim_gid))
- DEBUG(D_hints_lookup)
- debug_printf_indent("failed setting %s to owned by exim\n", filename);
- }
- }
-
- closedir(dd);
- }
+priv_restore();
/* If the open has failed, return NULL, leaving errno set. If lof is TRUE,
log the event - also for debugging - but debug only if the file just doesn't
git://git.exim.org / exim.git / commitdiff