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authorLennart Poettering <lennart@poettering.net>2016-02-10 22:58:41 +0100
committerLennart Poettering <lennart@poettering.net>2016-02-10 23:42:34 +0100
commitcf3bdcfeba48ffef71f1f59e092c4fb9275dcb3a (patch)
treec6de01115847ac95b2a33fc185740bf68c4e4b91 /src/nss-mymachines
parent648b122045182a1ac19d1622817e2a350beb0354 (diff)
nss-mymachines: never resolve unmapped UIDs/GIDs
Don't ever permit successful user or group lookups if no UID/GID mapping is actually applied. THis way, we can be sure that nss-mymachines cannot be used to insert invalid cache entries into nscd's cache. https://bugzilla.redhat.com/show_bug.cgi?id=1285339
Diffstat (limited to 'src/nss-mymachines')
-rw-r--r--src/nss-mymachines/nss-mymachines.c20
1 files changed, 18 insertions, 2 deletions
diff --git a/src/nss-mymachines/nss-mymachines.c b/src/nss-mymachines/nss-mymachines.c
index 78133a39bf..1582d702f8 100644
--- a/src/nss-mymachines/nss-mymachines.c
+++ b/src/nss-mymachines/nss-mymachines.c
@@ -38,6 +38,9 @@ NSS_GETHOSTBYNAME_PROTOTYPES(mymachines);
NSS_GETPW_PROTOTYPES(mymachines);
NSS_GETGR_PROTOTYPES(mymachines);
+#define HOST_UID_LIMIT ((uid_t) UINT32_C(0x10000))
+#define HOST_GID_LIMIT ((gid_t) UINT32_C(0x10000))
+
static int count_addresses(sd_bus_message *m, int af, unsigned *ret) {
unsigned c = 0;
int r;
@@ -455,6 +458,10 @@ enum nss_status _nss_mymachines_getpwnam_r(
if (r < 0)
goto fail;
+ /* Refuse to work if the mapped address is in the host UID range, or if there was no mapping at all. */
+ if (mapped < HOST_UID_LIMIT || mapped == uid)
+ goto not_found;
+
l = strlen(name);
if (buflen < l+1) {
*errnop = ENOMEM;
@@ -504,7 +511,7 @@ enum nss_status _nss_mymachines_getpwuid_r(
}
/* We consider all uids < 65536 host uids */
- if (uid < 0x10000)
+ if (uid < HOST_UID_LIMIT)
goto not_found;
r = sd_bus_open_system(&bus);
@@ -531,6 +538,9 @@ enum nss_status _nss_mymachines_getpwuid_r(
if (r < 0)
goto fail;
+ if (mapped == uid)
+ goto not_found;
+
if (snprintf(buffer, buflen, "vu-%s-" UID_FMT, machine, (uid_t) mapped) >= (int) buflen) {
*errnop = ENOMEM;
return NSS_STATUS_TRYAGAIN;
@@ -619,6 +629,9 @@ enum nss_status _nss_mymachines_getgrnam_r(
if (r < 0)
goto fail;
+ if (mapped < HOST_GID_LIMIT || mapped == gid)
+ goto not_found;
+
l = sizeof(char*) + strlen(name) + 1;
if (buflen < l) {
*errnop = ENOMEM;
@@ -666,7 +679,7 @@ enum nss_status _nss_mymachines_getgrgid_r(
}
/* We consider all gids < 65536 host gids */
- if (gid < 0x10000)
+ if (gid < HOST_GID_LIMIT)
goto not_found;
r = sd_bus_open_system(&bus);
@@ -693,6 +706,9 @@ enum nss_status _nss_mymachines_getgrgid_r(
if (r < 0)
goto fail;
+ if (mapped == gid)
+ goto not_found;
+
if (buflen < sizeof(char*) + 1) {
*errnop = ENOMEM;
return NSS_STATUS_TRYAGAIN;