RESPONDERS: Make the fd_limit setting configurable

This code will now attempt first to see if it has privilege to set
the value as specified, and if not it will fall back to the
previous behavior. So on systems with the CAP_SYS_RESOURCE
capability granted to SSSD, it will be able to ignore the
limits.conf hard limit.

https://fedorahosted.org/sssd/ticket/1197

7 files changed, 63 insertions, 4 deletions

diff --git a/src/config/SSSDConfig.py b/src/config/SSSDConfig.py
index a545800b8..0ff5a6c05 100644
--- a/src/config/SSSDConfig.py
+++ b/src/config/SSSDConfig.py
@@ -43,6 +43,7 @@ option_strings = {
     'timeout' : _('Ping timeout before restarting service'),
     'command' : _('Command to start service'),
     'reconnection_retries' : _('Number of times to attempt connection to Data Providers'),
+    'fd_limit' : _('The number of file descriptors that may be opened by this responder'),
 
     # [sssd]
     'services' : _('SSSD Services to start'),
diff --git a/src/config/SSSDConfigTest.py b/src/config/SSSDConfigTest.py
index a64a73616..7e024caa0 100755
--- a/src/config/SSSDConfigTest.py
+++ b/src/config/SSSDConfigTest.py
@@ -272,7 +272,8 @@ class SSSDConfigTestSSSDService(unittest.TestCase):
             'debug_microseconds',
             'debug_to_files',
             'command',
-            'reconnection_retries']
+            'reconnection_retries',
+            'fd_limit']
 
         self.assertTrue(type(options) == dict,
                         "Options should be a dictionary")
diff --git a/src/config/etc/sssd.api.conf b/src/config/etc/sssd.api.conf
index 934346350..155b8efef 100644
--- a/src/config/etc/sssd.api.conf
+++ b/src/config/etc/sssd.api.conf
@@ -9,6 +9,7 @@ debug_microseconds = bool, None, false
 debug_to_files = bool, None, false
 command = str, None, false
 reconnection_retries = int, None, false
+fd_limit = int, None, false
 
 [sssd]
 # Monitor service
diff --git a/src/man/sssd.conf.5.xml b/src/man/sssd.conf.5.xml
index abebf8473..63e396a54 100644
--- a/src/man/sssd.conf.5.xml
+++ b/src/man/sssd.conf.5.xml
@@ -267,6 +267,23 @@
                     </listitem>
                 </varlistentry>
                 <varlistentry>
+                    <term>fd_limit</term>
+                    <listitem>
+                        <para>
+                            This option specifies the maximum number of file
+                            descriptors that may be opened at one time by this
+                            SSSD process. On systems where SSSD is granted the
+                            CAP_SYS_RESOURCE capability, this will be an
+                            absolute setting. On systems without this
+                            capability, the resulting value will be the lower
+                            value of this or the limits.conf "hard" limit.
+                        </para>
+                        <para>
+                            Default: 8192 (or limits.conf "hard" limit)
+                        </para>
+                    </listitem>
+                </varlistentry>
+                <varlistentry>
                     <term>command (string)</term>
                     <listitem>
                         <para>
diff --git a/src/responder/common/responder_common.c b/src/responder/common/responder_common.c
index 94a9fdb63..a9b5d56b0 100644
--- a/src/responder/common/responder_common.c
+++ b/src/responder/common/responder_common.c
@@ -654,7 +654,24 @@ void responder_set_fd_limit(rlim_t fd_limit)
     struct rlimit current_limit, new_limit;
     int limret;
 
-    /* First determine the maximum hard limit */
+    /* First, let's see if we have permission to just set
+     * the value as-is.
+     */
+    new_limit.rlim_cur = fd_limit;
+    new_limit.rlim_max = fd_limit;
+    limret = setrlimit(RLIMIT_NOFILE, &new_limit);
+    if (limret == 0) {
+        DEBUG(SSSDBG_CONF_SETTINGS,
+              ("Maximum file descriptors set to [%d]\n",
+               new_limit.rlim_cur));
+        return;
+    }
+
+    /* We couldn't set the soft and hard limits to this
+     * value. Let's see how high we CAN set it.
+     */
+
+    /* Determine the maximum hard limit */
     limret = getrlimit(RLIMIT_NOFILE, &current_limit);
     if (limret == 0) {
         DEBUG(SSSDBG_TRACE_INTERNAL,
diff --git a/src/responder/nss/nsssrv.c b/src/responder/nss/nsssrv.c
index 3c23f1bf9..ef66b22fb 100644
--- a/src/responder/nss/nsssrv.c
+++ b/src/responder/nss/nsssrv.c
@@ -251,6 +251,7 @@ int nss_process_init(TALLOC_CTX *mem_ctx,
     struct nss_ctx *nctx;
     int ret, max_retries;
     int hret;
+    int fd_limit;
 
     nctx = talloc_zero(mem_ctx, struct nss_ctx);
     if (!nctx) {
@@ -309,7 +310,17 @@ int nss_process_init(TALLOC_CTX *mem_ctx,
     }
 
     /* Set up file descriptor limits */
-    responder_set_fd_limit(DEFAULT_NSS_FD_LIMIT);
+    ret = confdb_get_int(nctx->rctx->cdb, nctx->rctx,
+                         CONFDB_NSS_CONF_ENTRY,
+                         CONFDB_SERVICE_FD_LIMIT,
+                         DEFAULT_NSS_FD_LIMIT,
+                         &fd_limit);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_FATAL_FAILURE,
+              ("Failed to set up file descriptor limit\n"));
+        return ret;
+    }
+    responder_set_fd_limit(fd_limit);
 
     DEBUG(1, ("NSS Initialization complete\n"));
 
diff --git a/src/responder/pam/pamsrv.c b/src/responder/pam/pamsrv.c
index 2786fe4e0..6cb564a7a 100644
--- a/src/responder/pam/pamsrv.c
+++ b/src/responder/pam/pamsrv.c
@@ -111,6 +111,7 @@ static int pam_process_init(TALLOC_CTX *mem_ctx,
     struct pam_ctx *pctx;
     int ret, max_retries;
     int id_timeout;
+    int fd_limit;
 
     pctx = talloc_zero(mem_ctx, struct pam_ctx);
     if (!pctx) {
@@ -186,7 +187,17 @@ static int pam_process_init(TALLOC_CTX *mem_ctx,
     }
 
     /* Set up file descriptor limits */
-    responder_set_fd_limit(DEFAULT_PAM_FD_LIMIT);
+    ret = confdb_get_int(pctx->rctx->cdb, pctx->rctx,
+                         CONFDB_PAM_CONF_ENTRY,
+                         CONFDB_SERVICE_FD_LIMIT,
+                         DEFAULT_PAM_FD_LIMIT,
+                         &fd_limit);
+    if (ret != EOK) {
+        DEBUG(SSSDBG_FATAL_FAILURE,
+              ("Failed to set up file descriptor limit\n"));
+        return ret;
+    }
+    responder_set_fd_limit(fd_limit);
 
     ret = EOK;