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pam/SOURCES/pam-1.5.1-pam-limits-unlimi...

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From 3234488f2c52a021eec87df1990d256314c21bff Mon Sep 17 00:00:00 2001
From: Josef Moellers <jmoellers@suse.de>
Date: Wed, 14 Apr 2021 16:39:28 +0200
Subject: [PATCH] pam_limits: "Unlimited" is not a valid value for
RLIMIT_NOFILE.
Replace it with a value obtained from /proc/sys/fs/nr_open
* modules/pam_limits/limits.conf.5.xml: Document the replacement.
* modules/pam_limits/pam_limits.c: Replace unlimited RLIMIT_NOFILE
value with a value obtained from /proc/sys/fs/nr_open
---
modules/pam_limits/limits.conf.5.xml | 2 ++
modules/pam_limits/pam_limits.c | 49 ++++++++++++++++++++++++++++
2 files changed, 51 insertions(+)
diff --git a/modules/pam_limits/limits.conf.5.xml b/modules/pam_limits/limits.conf.5.xml
index cd64ac90..c5bd6768 100644
--- a/modules/pam_limits/limits.conf.5.xml
+++ b/modules/pam_limits/limits.conf.5.xml
@@ -283,6 +283,8 @@
<emphasis>unlimited</emphasis> or <emphasis>infinity</emphasis> indicating no limit,
except for <emphasis remap='B'>priority</emphasis>, <emphasis remap='B'>nice</emphasis>,
and <emphasis remap='B'>nonewprivs</emphasis>.
+ If <emphasis remap='B'>nofile</emphasis> is to be set to one of these values,
+ it will be set to the contents of /proc/sys/fs/nr_open instead (see setrlimit(3)).
</para>
<para>
If a hard limit or soft limit of a resource is set to a valid value,
diff --git a/modules/pam_limits/pam_limits.c b/modules/pam_limits/pam_limits.c
index 10049973..7cc45d77 100644
--- a/modules/pam_limits/pam_limits.c
+++ b/modules/pam_limits/pam_limits.c
@@ -487,6 +487,41 @@ static int init_limits(pam_handle_t *pamh, struct pam_limit_s *pl, int ctrl)
return retval;
}
+/*
+ * Read the contents of <pathname> and return it in *valuep
+ * return 1 if conversion succeeds, result is in *valuep
+ * return 0 if conversion fails, *valuep is untouched.
+ */
+static int
+value_from_file(const char *pathname, rlim_t *valuep)
+{
+ char buf[128];
+ FILE *fp;
+ int retval;
+
+ retval = 0;
+
+ if ((fp = fopen(pathname, "r")) != NULL) {
+ if (fgets(buf, sizeof(buf), fp) != NULL) {
+ char *endptr;
+ unsigned long long value;
+
+ errno = 0;
+ value = strtoull(buf, &endptr, 10);
+ if (endptr != buf &&
+ (value != ULLONG_MAX || errno == 0) &&
+ (unsigned long long) (rlim_t) value == value) {
+ *valuep = (rlim_t) value;
+ retval = 1;
+ }
+ }
+
+ fclose(fp);
+ }
+
+ return retval;
+}
+
static void
process_limit (const pam_handle_t *pamh, int source, const char *lim_type,
const char *lim_item, const char *lim_value,
@@ -666,6 +701,20 @@ process_limit (const pam_handle_t *pamh, int source, const char *lim_type,
rlimit_value = 20 - int_value;
break;
#endif
+ case RLIMIT_NOFILE:
+ /*
+ * If nofile is to be set to "unlimited", try to set it to
+ * the value in /proc/sys/fs/nr_open instead.
+ */
+ if (rlimit_value == RLIM_INFINITY) {
+ if (!value_from_file("/proc/sys/fs/nr_open", &rlimit_value))
+ pam_syslog(pamh, LOG_WARNING,
+ "Cannot set \"nofile\" to a sensible value");
+ else if (ctrl & PAM_DEBUG_ARG)
+ pam_syslog(pamh, LOG_DEBUG, "Setting \"nofile\" limit to %llu",
+ (unsigned long long) rlimit_value);
+ }
+ break;
}
if ( (limit_item != LIMIT_LOGIN)
--
2.33.1