support alternate backends for the passwd and group dbs

[musl] / src / passwd / getpw_a.c

diff --git a/src/passwd/getpw_a.c b/src/passwd/getpw_a.c
index 21efc5c..b04663d 100644 (file)
--- a/src/passwd/getpw_a.c
+++ b/src/passwd/getpw_a.c
@@ -1,5 +1,21 @@
-#include "pwf.h"
 #include <pthread.h>
+#include <byteswap.h>
+#include <string.h>
+#include <unistd.h>
+#include "pwf.h"
+#include "nscd.h"
+
+static char *itoa(char *p, uint32_t x)
+{
+       // number of digits in a uint32_t + NUL
+       p += 11;
+       *--p = 0;
+       do {
+               *--p = '0' + x % 10;
+               x /= 10;
+       } while (x);
+       return p;
+}
 
 int __getpw_a(const char *name, uid_t uid, struct passwd *pw, char **buf, size_t *size, struct passwd **res)
 {
@@ -24,6 +40,102 @@ int __getpw_a(const char *name, uid_t uid, struct passwd *pw, char **buf, size_t
        }
        fclose(f);
 
+       if (!*res && (rv == 0 || rv == ENOENT || rv == ENOTDIR)) {
+               int32_t req = name ? GETPWBYNAME : GETPWBYUID;
+               const char *key;
+               int32_t passwdbuf[PW_LEN] = {0};
+               size_t len = 0;
+               char uidbuf[11] = {0};
+
+               if (name) {
+                       key = name;
+               } else {
+                       /* uid outside of this range can't be queried with the
+                        * nscd interface, but might happen if uid_t ever
+                        * happens to be a larger type (this is not true as of
+                        * now)
+                        */
+                       if(uid < 0 || uid > UINT32_MAX) {
+                               rv = 0;
+                               goto done;
+                       }
+                       key = itoa(uidbuf, uid);
+               }
+
+               f = __nscd_query(req, key, passwdbuf, sizeof passwdbuf, (int[]){0});
+               if (!f) { rv = errno; goto done; }
+               if (f == (FILE*)-1) { rv = 0; goto done; }
+
+               if(!passwdbuf[PWFOUND]) { rv = 0; goto cleanup_f; }
+
+               /* A zero length response from nscd is invalid. We ignore
+                * invalid responses and just report an error, rather than
+                * trying to do something with them.
+                */
+               if (!passwdbuf[PWNAMELEN] || !passwdbuf[PWPASSWDLEN]
+               || !passwdbuf[PWGECOSLEN] || !passwdbuf[PWDIRLEN]
+               || !passwdbuf[PWSHELLLEN]) {
+                       rv = EIO;
+                       goto cleanup_f;
+               }
+
+               if ((passwdbuf[PWNAMELEN]|passwdbuf[PWPASSWDLEN]
+                    |passwdbuf[PWGECOSLEN]|passwdbuf[PWDIRLEN]
+                    |passwdbuf[PWSHELLLEN]) >= SIZE_MAX/8) {
+                       rv = ENOMEM;
+                       goto cleanup_f;
+               }
+
+               len = passwdbuf[PWNAMELEN] + passwdbuf[PWPASSWDLEN]
+                   + passwdbuf[PWGECOSLEN] + passwdbuf[PWDIRLEN]
+                   + passwdbuf[PWSHELLLEN];
+
+               if (len > *size || !*buf) {
+                       char *tmp = realloc(*buf, len);
+                       if (!tmp) {
+                               rv = errno;
+                               goto cleanup_f;
+                       }
+                       *buf = tmp;
+                       *size = len;
+               }
+
+               if (!fread(*buf, len, 1, f)) {
+                       rv = ferror(f) ? errno : EIO;
+                       goto cleanup_f;
+               }
+
+               pw->pw_name = *buf;
+               pw->pw_passwd = pw->pw_name + passwdbuf[PWNAMELEN];
+               pw->pw_gecos = pw->pw_passwd + passwdbuf[PWPASSWDLEN];
+               pw->pw_dir = pw->pw_gecos + passwdbuf[PWGECOSLEN];
+               pw->pw_shell = pw->pw_dir + passwdbuf[PWDIRLEN];
+               pw->pw_uid = passwdbuf[PWUID];
+               pw->pw_gid = passwdbuf[PWGID];
+
+               /* Don't assume that nscd made sure to null terminate strings.
+                * It's supposed to, but malicious nscd should be ignored
+                * rather than causing a crash.
+                */
+               if (pw->pw_passwd[-1] || pw->pw_gecos[-1] || pw->pw_dir[-1]
+               || pw->pw_shell[passwdbuf[PWSHELLLEN]-1]) {
+                       rv = EIO;
+                       goto cleanup_f;
+               }
+
+               if (name && strcmp(name, pw->pw_name)
+               || !name && uid != pw->pw_uid) {
+                       rv = EIO;
+                       goto cleanup_f;
+               }
+
+
+               *res = pw;
+cleanup_f:
+               fclose(f);
+               goto done;
+       }
+
 done:
        pthread_setcancelstate(cs, 0);
        if (rv) errno = rv;