diff options
Diffstat (limited to 'src/nss-resolve/nss-resolve.c')
| -rw-r--r-- | src/nss-resolve/nss-resolve.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/src/nss-resolve/nss-resolve.c b/src/nss-resolve/nss-resolve.c index b2bb698ded..a28b5d8ba8 100644 --- a/src/nss-resolve/nss-resolve.c +++ b/src/nss-resolve/nss-resolve.c @@ -91,6 +91,20 @@ static uint32_t ifindex_to_scopeid(int family, const void *a, int ifindex) { return IN6_IS_ADDR_LINKLOCAL(&in6) ? ifindex : 0; } +static bool avoid_deadlock(void) { + + /* Check whether this lookup might have a chance of deadlocking because we are called from the service manager + * code activating systemd-resolved.service. After all, we shouldn't synchronously do lookups to + * systemd-resolved if we are required to finish before it can be started. This of course won't detect all + * possible dead locks of this kind, but it should work for the most obvious cases. */ + + if (geteuid() != 0) /* Ignore the env vars unless we are privileged. */ + return false; + + return streq_ptr(getenv("SYSTEMD_ACTIVATION_UNIT"), "systemd-resolved.service") && + streq_ptr(getenv("SYSTEMD_ACTIVATION_SCOPE"), "system"); +} + enum nss_status _nss_resolve_gethostbyname4_r( const char *name, struct gaih_addrtuple **pat, @@ -117,6 +131,11 @@ enum nss_status _nss_resolve_gethostbyname4_r( assert(errnop); assert(h_errnop); + if (avoid_deadlock()) { + r = -EDEADLK; + goto fail; + } + r = sd_bus_open_system(&bus); if (r < 0) goto fail; @@ -292,6 +311,11 @@ enum nss_status _nss_resolve_gethostbyname3_r( goto fail; } + if (avoid_deadlock()) { + r = -EDEADLK; + goto fail; + } + r = sd_bus_open_system(&bus); if (r < 0) goto fail; @@ -479,6 +503,11 @@ enum nss_status _nss_resolve_gethostbyaddr2_r( return NSS_STATUS_UNAVAIL; } + if (avoid_deadlock()) { + r = -EDEADLK; + goto fail; + } + r = sd_bus_open_system(&bus); if (r < 0) goto fail; |