UTIL: Add a function to convert id_t from a number or a name

We need a custom function that would convert a numeric or string input
into uid_t. The function will be used to drop privileges in servers and
also in the PAC and IFP responders.

Includes a unit test to test all code that changed as well as a fix for
a misnamed attribute in the csv_to_uid_list function synopsis.

Reviewed-by: Pavel Reichl <preichl@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
(cherry picked from commit 5eda23c28c582b43b2a0a165b1750f3875c0fa84)

1 files changed, 44 insertions, 0 deletions

diff --git a/src/util/usertools.c b/src/util/usertools.c
index 809b42d67..a0b914e2f 100644
--- a/src/util/usertools.c
+++ b/src/util/usertools.c
@@ -23,8 +23,11 @@
 #include <pcre.h>
 #include <errno.h>
 #include <talloc.h>
+#include <pwd.h>
+#include <grp.h>
 
 #include "confdb/confdb.h"
+#include "util/strtonum.h"
 #include "util/util.h"
 #include "util/safe-format-string.h"
 #include "responder/common/responder.h"
@@ -659,3 +662,44 @@ sss_get_domain_name(TALLOC_CTX *mem_ctx,
 
     return user_name;
 }
+
+errno_t sss_user_by_name_or_uid(const char *input, uid_t *_uid, gid_t *_gid)
+{
+    uid_t uid;
+    errno_t ret;
+    char *endptr;
+    struct passwd *pwd;
+
+    /* Try if it's an ID first */
+    errno = 0;
+    uid = strtouint32(input, &endptr, 10);
+    if (errno != 0 || *endptr != '\0') {
+        ret = errno;
+        if (ret == ERANGE) {
+            DEBUG(SSSDBG_OP_FAILURE,
+                  "UID [%s] is out of range.\n", input);
+            return ret;
+        }
+
+        /* Nope, maybe a username? */
+        pwd = getpwnam(input);
+    } else {
+        pwd = getpwuid(uid);
+    }
+
+    if (pwd == NULL) {
+        DEBUG(SSSDBG_OP_FAILURE,
+              "[%s] is neither a valid UID nor a user name which could be "
+              "resolved by getpwnam().\n", input);
+        return EINVAL;
+    }
+
+    if (_uid) {
+        *_uid = pwd->pw_uid;
+    }
+
+    if (_gid) {
+        *_gid = pwd->pw_gid;
+    }
+    return EOK;
+}