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|
Description: Allow explicit limits for root and reset limits on each session
When crossing session boundaries (such as when su'ing from one user to
another), if the target account has no limit specified in limits.conf we
want to use the default, not the current value configured for the
source account.
.
On Linux, we query default limits by parsing /proc/1/limits, so that we
can sanely inherit kernel defaults that vary with system resources (such as
nproc). If /proc/1/limits is unavailable, fall back to a set of
hard-coded values that shadow the currently known defaults on Linux.
.
Also, don't apply wildcard limits to the root account; only apply limits to
root that reference root by name.
Author: Peter Paluch <peterp@frcatel.fri.utc.sk>,
Ben Collins <bcollins@debian.org>,
Steve Langasek <vorlon@debian.org>,
Kees Cook <kees@ubuntu.com>
Bug-Ubuntu: https://launchpad.net/bugs/746655
Bug-Debian: http://bugs.debian.org/63230
Bug-Debian: http://bugs.debian.org/620302
Forwarded: https://fedorahosted.org/pipermail/pam-developers/2011-March/000017.html
Index: pam-debian/modules/pam_limits/pam_limits.c
===================================================================
--- pam-debian.orig/modules/pam_limits/pam_limits.c
+++ pam-debian/modules/pam_limits/pam_limits.c
@@ -45,15 +45,24 @@
#include <libaudit.h>
#endif
+#ifndef MLOCK_LIMIT
+#ifdef __FreeBSD_kernel__
+#define MLOCK_LIMIT RLIM_INFINITY
+#else
+#define MLOCK_LIMIT (64*1024)
+#endif
+#endif
+
/* Module defines */
#define LINE_LENGTH 1024
#define LIMITS_DEF_USER 0 /* limit was set by an user entry */
#define LIMITS_DEF_GROUP 1 /* limit was set by a group entry */
#define LIMITS_DEF_ALLGROUP 2 /* limit was set by a group entry */
-#define LIMITS_DEF_ALL 3 /* limit was set by an default entry */
-#define LIMITS_DEF_DEFAULT 4 /* limit was set by an default entry */
-#define LIMITS_DEF_NONE 5 /* this limit was not set yet */
+#define LIMITS_DEF_ALL 3 /* limit was set by an all entry */
+#define LIMITS_DEF_DEFAULT 4 /* limit was set by an internal default entry */
+#define LIMITS_DEF_KERNEL 5 /* limit was set from /proc/1/limits */
+#define LIMITS_DEF_NONE 6 /* this limit was not set yet */
static const char *limits_def_names[] = {
"USER",
@@ -61,6 +70,7 @@
"ALLGROUP",
"ALL",
"DEFAULT",
+ "KERNEL",
"NONE",
NULL
};
@@ -74,6 +84,7 @@
/* internal data */
struct pam_limit_s {
+ int root; /* running as root? */
int login_limit; /* the max logins limit */
int login_limit_def; /* which entry set the login limit */
int flag_numsyslogins; /* whether to limit logins only for a
@@ -291,13 +302,155 @@
return 0;
}
-static int init_limits(struct pam_limit_s *pl)
+static const char * lnames[RLIM_NLIMITS] = {
+ [RLIMIT_CPU] = "Max cpu time",
+ [RLIMIT_FSIZE] = "Max file size",
+ [RLIMIT_DATA] = "Max data size",
+ [RLIMIT_STACK] = "Max stack size",
+ [RLIMIT_CORE] = "Max core file size",
+ [RLIMIT_RSS] = "Max resident set",
+ [RLIMIT_NPROC] = "Max processes",
+ [RLIMIT_NOFILE] = "Max open files",
+ [RLIMIT_MEMLOCK] = "Max locked memory",
+#ifdef RLIMIT_AS
+ [RLIMIT_AS] = "Max address space",
+#endif
+#ifdef RLIMIT_LOCKS
+ [RLIMIT_LOCKS] = "Max file locks",
+#endif
+#ifdef RLIMIT_SIGPENDING
+ [RLIMIT_SIGPENDING] = "Max pending signals",
+#endif
+#ifdef RLIMIT_MSGQUEUE
+ [RLIMIT_MSGQUEUE] = "Max msgqueue size",
+#endif
+#ifdef RLIMIT_NICE
+ [RLIMIT_NICE] = "Max nice priority",
+#endif
+#ifdef RLIMIT_RTPRIO
+ [RLIMIT_RTPRIO] = "Max realtime priority",
+#endif
+#ifdef RLIMIT_RTTIME
+ [RLIMIT_RTTIME] = "Max realtime timeout",
+#endif
+};
+
+static int str2rlimit(char *name) {
+ int i;
+ if (!name || *name == '\0')
+ return -1;
+ for(i = 0; i < RLIM_NLIMITS; i++) {
+ if (strcmp(name, lnames[i]) == 0) return i;
+ }
+ return -1;
+}
+
+static rlim_t str2rlim_t(char *value) {
+ unsigned long long rlimit = 0;
+
+ if (!value) return (rlim_t)rlimit;
+ if (strcmp(value, "unlimited") == 0) {
+ return RLIM_INFINITY;
+ }
+ rlimit = strtoull(value, NULL, 10);
+ return (rlim_t)rlimit;
+}
+
+#define LIMITS_SKIP_WHITESPACE { \
+ /* step backwards over spaces */ \
+ pos--; \
+ while (pos && line[pos] == ' ') pos--; \
+ if (!pos) continue; \
+ line[pos+1] = '\0'; \
+}
+#define LIMITS_MARK_ITEM(item) { \
+ /* step backwards over non-spaces */ \
+ pos--; \
+ while (pos && line[pos] != ' ') pos--; \
+ if (!pos) continue; \
+ item = line + pos + 1; \
+}
+
+static void parse_kernel_limits(pam_handle_t *pamh, struct pam_limit_s *pl, int ctrl)
+{
+ int i, maxlen = 0;
+ FILE *limitsfile;
+ const char *proclimits = "/proc/1/limits";
+ char line[256];
+ char *units, *hard, *soft, *name;
+
+ if (!(limitsfile = fopen(proclimits, "r"))) {
+ pam_syslog(pamh, LOG_WARNING, "Could not read %s (%s), using PAM internal defaults", proclimits, strerror(errno));
+ return;
+ }
+
+ while (fgets(line, 256, limitsfile)) {
+ int pos = strlen(line);
+ if (pos < 2) continue;
+
+ /* drop trailing newline */
+ if (line[pos-1] == '\n') {
+ pos--;
+ line[pos] = '\0';
+ }
+
+ /* determine formatting boundry of limits report */
+ if (!maxlen && strncmp(line, "Limit", 5) == 0) {
+ maxlen = pos;
+ continue;
+ }
+
+ if (pos == maxlen) {
+ /* step backwards over "Units" name */
+ LIMITS_SKIP_WHITESPACE;
+ LIMITS_MARK_ITEM(units);
+ }
+ else {
+ units = "";
+ }
+
+ /* step backwards over "Hard Limit" value */
+ LIMITS_SKIP_WHITESPACE;
+ LIMITS_MARK_ITEM(hard);
+
+ /* step backwards over "Soft Limit" value */
+ LIMITS_SKIP_WHITESPACE;
+ LIMITS_MARK_ITEM(soft);
+
+ /* step backwards over name of limit */
+ LIMITS_SKIP_WHITESPACE;
+ name = line;
+
+ i = str2rlimit(name);
+ if (i < 0 || i >= RLIM_NLIMITS) {
+ if (ctrl & PAM_DEBUG_ARG)
+ pam_syslog(pamh, LOG_DEBUG, "Unknown kernel rlimit '%s' ignored", name);
+ continue;
+ }
+ pl->limits[i].limit.rlim_cur = str2rlim_t(soft);
+ pl->limits[i].limit.rlim_max = str2rlim_t(hard);
+ pl->limits[i].src_soft = LIMITS_DEF_KERNEL;
+ pl->limits[i].src_hard = LIMITS_DEF_KERNEL;
+ }
+ fclose(limitsfile);
+}
+
+static int init_limits(pam_handle_t *pamh, struct pam_limit_s *pl, int ctrl)
{
int i;
int retval = PAM_SUCCESS;
+ static int mlock_limit = 0;
D(("called."));
+ pl->root = 0;
+
+ if (mlock_limit == 0) {
+ mlock_limit = sysconf(_SC_PAGESIZE);
+ if (mlock_limit < MLOCK_LIMIT)
+ mlock_limit = MLOCK_LIMIT;
+ }
+
for(i = 0; i < RLIM_NLIMITS; i++) {
int r = getrlimit(i, &pl->limits[i].limit);
if (r == -1) {
@@ -312,6 +465,71 @@
}
}
+#ifdef __linux__
+ parse_kernel_limits(pamh, pl, ctrl);
+#endif
+
+ for(i = 0; i < RLIM_NLIMITS; i++) {
+ if (pl->limits[i].supported &&
+ (pl->limits[i].src_soft == LIMITS_DEF_NONE ||
+ pl->limits[i].src_hard == LIMITS_DEF_NONE)) {
+#ifdef __linux__
+ pam_syslog(pamh, LOG_WARNING, "Did not find kernel RLIMIT for %s, using PAM internal default", rlimit2str(i));
+#endif
+
+ pl->limits[i].src_soft = LIMITS_DEF_DEFAULT;
+ pl->limits[i].src_hard = LIMITS_DEF_DEFAULT;
+ switch(i) {
+ case RLIMIT_CPU:
+ case RLIMIT_FSIZE:
+ case RLIMIT_DATA:
+ case RLIMIT_RSS:
+ case RLIMIT_NPROC:
+#ifdef RLIMIT_AS
+ case RLIMIT_AS:
+#endif
+#ifdef RLIMIT_LOCKS
+ case RLIMIT_LOCKS:
+#endif
+ pl->limits[i].limit.rlim_cur = RLIM_INFINITY;
+ pl->limits[i].limit.rlim_max = RLIM_INFINITY;
+ break;
+ case RLIMIT_MEMLOCK:
+ pl->limits[i].limit.rlim_cur = mlock_limit;
+ pl->limits[i].limit.rlim_max = mlock_limit;
+ break;
+#ifdef RLIMIT_SIGPENDING
+ case RLIMIT_SIGPENDING:
+ pl->limits[i].limit.rlim_cur = 16382;
+ pl->limits[i].limit.rlim_max = 16382;
+ break;
+#endif
+#ifdef RLIMIT_MSGQUEUE
+ case RLIMIT_MSGQUEUE:
+ pl->limits[i].limit.rlim_cur = 819200;
+ pl->limits[i].limit.rlim_max = 819200;
+ break;
+#endif
+ case RLIMIT_CORE:
+ pl->limits[i].limit.rlim_cur = 0;
+ pl->limits[i].limit.rlim_max = RLIM_INFINITY;
+ break;
+ case RLIMIT_STACK:
+ pl->limits[i].limit.rlim_cur = 8192*1024;
+ pl->limits[i].limit.rlim_max = RLIM_INFINITY;
+ break;
+ case RLIMIT_NOFILE:
+ pl->limits[i].limit.rlim_cur = 1024;
+ pl->limits[i].limit.rlim_max = 1024;
+ break;
+ default:
+ pl->limits[i].src_soft = LIMITS_DEF_NONE;
+ pl->limits[i].src_hard = LIMITS_DEF_NONE;
+ break;
+ }
+ }
+ }
+
errno = 0;
pl->priority = getpriority (PRIO_PROCESS, 0);
if (pl->priority == -1 && errno != 0)
@@ -591,7 +809,7 @@
if (strcmp(uname, domain) == 0) /* this user have a limit */
process_limit(pamh, LIMITS_DEF_USER, ltype, item, value, ctrl, pl);
- else if (domain[0]=='@') {
+ else if (domain[0]=='@' && !pl->root) {
if (ctrl & PAM_DEBUG_ARG) {
pam_syslog(pamh, LOG_DEBUG,
"checking if %s is in group %s",
@@ -600,7 +818,7 @@
if (pam_modutil_user_in_group_nam_nam(pamh, uname, domain+1))
process_limit(pamh, LIMITS_DEF_GROUP, ltype, item, value, ctrl,
pl);
- } else if (domain[0]=='%') {
+ } else if (domain[0]=='%' && !pl->root) {
if (ctrl & PAM_DEBUG_ARG) {
pam_syslog(pamh, LOG_DEBUG,
"checking if %s is in group %s",
@@ -614,7 +832,7 @@
process_limit(pamh, LIMITS_DEF_ALLGROUP, ltype, item, value, ctrl,
pl);
}
- } else if (strcmp(domain, "*") == 0)
+ } else if (strcmp(domain, "*") == 0 && !pl->root)
process_limit(pamh, LIMITS_DEF_DEFAULT, ltype, item, value, ctrl,
pl);
} else if (i == 2 && ltype[0] == '-') { /* Probably a no-limit line */
@@ -743,12 +961,14 @@
return PAM_USER_UNKNOWN;
}
- retval = init_limits(pl);
+ retval = init_limits(pamh, pl, ctrl);
if (retval != PAM_SUCCESS) {
pam_syslog(pamh, LOG_WARNING, "cannot initialize");
return PAM_ABORT;
}
+ if (pwd->pw_uid == 0)
+ pl->root = 1;
retval = parse_config_file(pamh, pwd->pw_name, ctrl, pl);
if (retval == PAM_IGNORE) {
D(("the configuration file ('%s') has an applicable '<domain> -' entry", CONF_FILE));
Index: pam-debian/modules/pam_limits/limits.conf
===================================================================
--- pam-debian.orig/modules/pam_limits/limits.conf
+++ pam-debian/modules/pam_limits/limits.conf
@@ -11,6 +11,9 @@
# - the wildcard *, for default entry
# - the wildcard %, can be also used with %group syntax,
# for maxlogin limit
+# - NOTE: group and wildcard limits are not applied to root.
+# To apply a limit to the root user, <domain> must be
+# the literal username root.
#
#<type> can have the two values:
# - "soft" for enforcing the soft limits
@@ -41,6 +44,7 @@
#
#* soft core 0
+#root hard core 100000
#* hard rss 10000
#@student hard nproc 20
#@faculty soft nproc 20
Index: pam-debian/modules/pam_limits/limits.conf.5.xml
===================================================================
--- pam-debian.orig/modules/pam_limits/limits.conf.5.xml
+++ pam-debian/modules/pam_limits/limits.conf.5.xml
@@ -57,6 +57,11 @@
</para>
</listitem>
</itemizedlist>
+ <para>
+ <emphasis remap='B'>NOTE:</emphasis> group and wildcard limits are not
+ applied to the root user. To set a limit for the root user, this field
+ must contain the literal username <emphasis remap='B'>root</emphasis>.
+ </para>
</listitem>
</varlistentry>
@@ -278,6 +283,7 @@
</para>
<programlisting>
* soft core 0
+root hard core 100000
* hard rss 10000
@student hard nproc 20
@faculty soft nproc 20
Index: pam-debian/modules/pam_limits/limits.conf.5
===================================================================
--- pam-debian.orig/modules/pam_limits/limits.conf.5
+++ pam-debian/modules/pam_limits/limits.conf.5
@@ -93,6 +93,11 @@
\fI%group\fR
syntax\&.
.RE
+.RS 4
+
+\fBNOTE:\fR
+group and wildcard limits are not applied to the root user\&. To set a limit for the root user, this field must contain the literal username
+\fBroot\fR\&.
.RE
.PP
\fB<type>\fR
@@ -265,6 +270,7 @@
.\}
.nf
* soft core 0
+root hard core 100000
* hard rss 10000
@student hard nproc 20
@faculty soft nproc 20
Index: pam-debian/modules/pam_limits/README
===================================================================
--- pam-debian.orig/modules/pam_limits/README
+++ pam-debian/modules/pam_limits/README
@@ -55,6 +55,7 @@
limits.conf.
* soft core 0
+root hard core 100000
* hard rss 10000
@student hard nproc 20
@faculty soft nproc 20
|
