Merge commit 'refs/merge-requests/13' of git://gitorious.org/procps/procps into merge-requests/13

Conflicts:
	pgrep.c
	ps/output.c
	ps/ps.1

12 files changed, 350 insertions, 10 deletions

diff --git a/Makefile.am b/Makefile.am
index 9e900ac..3d66d60 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -55,7 +55,7 @@ EXTRA_DIST = \
 if BUILD_KILL
 bin_PROGRAMS = kill
 dist_man_MANS += kill.1
-kill_SOURCES = skill.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c
+kill_SOURCES = skill.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c $(top_srcdir)/lib/nsutils.c
 else
   EXTRA_DIST += kill.1
 endif
@@ -77,8 +77,8 @@ if BUILD_SKILL
 usrbin_exec_PROGRAMS += \
 	skill \
 	snice
-skill_SOURCES = skill.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c
-snice_SOURCES = skill.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c
+skill_SOURCES = skill.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c $(top_srcdir)/lib/nsutils.c
+snice_SOURCES = skill.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c $(top_srcdir)/lib/nsutils.c
 dist_man_MANS += \
 	skill.1 \
 	snice.1
@@ -89,8 +89,8 @@ else
 endif
 
 free_SOURCES = free.c $(top_srcdir)/lib/strutils.c $(top_srcdir)/lib/fileutils.c
-pgrep_SOURCES = pgrep.c $(top_srcdir)/lib/fileutils.c
-pkill_SOURCES = pgrep.c $(top_srcdir)/lib/fileutils.c
+pgrep_SOURCES = pgrep.c $(top_srcdir)/lib/fileutils.c $(top_srcdir)/lib/nsutils.c
+pkill_SOURCES = pgrep.c $(top_srcdir)/lib/fileutils.c $(top_srcdir)/lib/nsutils.c
 pmap_SOURCES = pmap.c $(top_srcdir)/lib/fileutils.c
 pwdx_SOURCES = pwdx.c $(top_srcdir)/lib/fileutils.c
 sysctl_SOURCES = sysctl.c $(top_srcdir)/lib/fileutils.c
diff --git a/include/nsutils.h b/include/nsutils.h
new file mode 100644
index 0000000..3235851
--- /dev/null
+++ b/include/nsutils.h
@@ -0,0 +1,7 @@
+#ifndef PROCPS_NG_NSUTILS
+#define PROCPS_NG_NSUTILS
+
+#include "proc/readproc.h"
+int ns_read(pid_t pid, proc_t *ns_task);
+
+#endif
diff --git a/lib/nsutils.c b/lib/nsutils.c
new file mode 100644
index 0000000..b97f446
--- /dev/null
+++ b/lib/nsutils.c
@@ -0,0 +1,32 @@
+#include <errno.h>
+#include <error.h>
+#include <stdio_ext.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "proc/readproc.h"
+#include "nsutils.h"
+
+/* we need to fill in only namespace information */
+int ns_read(pid_t pid, proc_t *ns_task)
+{
+	struct stat st;
+	char buff[50];
+	int i, rc = 0;
+
+	for (i = 0; i < NUM_NS; i++) {
+		snprintf(buff, sizeof(buff), "/proc/%i/ns/%s", pid,
+			get_ns_name(i));
+		if (stat(buff, &st)) {
+			if (errno != ENOENT)
+				rc = errno;
+			ns_task->ns[i] = 0;
+			continue;
+		}
+		ns_task->ns[i] = st.st_ino;
+	}
+	return rc;
+}
+
diff --git a/pgrep.1 b/pgrep.1
index a0e7376..c9860c7 100644
--- a/pgrep.1
+++ b/pgrep.1
@@ -146,6 +146,15 @@ than
 \fB\-L\fR, \fB\-\-logpidfile\fR
 Fail if pidfile (see -F) not locked.
 .TP
+\fB\-\-ns \fIpid\fP
+Match processes that belong to the same namespaces. Required to run as
+root to match processes from other users. See \-\-nslist for how to limit
+which namespaces to match.
+.TP
+\fB\-\-nslist \fIname\fP,...
+Match only the provided namespaces. Available namespaces:
+ipc, mnt, net, pid, user,uts.
+.TP
 \fB\-V\fR, \fB\-\-version\fR
 Display version information and exit.
 .TP
diff --git a/pgrep.c b/pgrep.c
index 6bc38ef..c7535f7 100644
--- a/pgrep.c
+++ b/pgrep.c
@@ -46,6 +46,7 @@
 
 #include "c.h"
 #include "fileutils.h"
+#include "nsutils.h"
 #include "nls.h"
 #include "xalloc.h"
 #include "proc/readproc.h"
@@ -76,6 +77,7 @@ static int opt_lock = 0;
 static int opt_case = 0;
 static int opt_echo = 0;
 static int opt_threads = 0;
+static pid_t opt_ns_pid = 0;
 
 static const char *opt_delim = "\n";
 static struct el *opt_pgrp = NULL;
@@ -86,9 +88,13 @@ static struct el *opt_sid = NULL;
 static struct el *opt_term = NULL;
 static struct el *opt_euid = NULL;
 static struct el *opt_ruid = NULL;
+static struct el *opt_nslist = NULL;
 static char *opt_pattern = NULL;
 static char *opt_pidfile = NULL;
 
+/* by default, all namespaces will be checked */
+static int ns_flags = 0x3f;
+
 static int __attribute__ ((__noreturn__)) usage(int opt)
 {
 	int err = (opt == '?');
@@ -121,7 +127,12 @@ static int __attribute__ ((__noreturn__)) usage(int opt)
 		" -U, --uid <id,...>        match by real IDs\n"
 		" -x, --exact               match exactly with the command name\n"
 		" -F, --pidfile <file>      read PIDs from file\n"
-		" -L, --logpidfile          fail if PID file is not locked\n"), fp);
+		" -L, --logpidfile          fail if PID file is not locked\n"
+		" --ns <pid>                match the processes that belong to the same\n"
+		"                           namespace as <pid>\n"
+		" --nslist <ns,...>         list which namespaces will be considered for\n"
+		"                           the --ns option.\n"
+		"                           Available namespaces: ipc, mnt, net, pid, user, uts\n"), fp);
 	fputs(USAGE_SEPARATOR, fp);
 	fputs(USAGE_HELP, fp);
 	fputs(USAGE_VERSION, fp);
@@ -320,6 +331,20 @@ static int conv_str (const char *restrict name, struct el *restrict e)
 }
 
 
+static int conv_ns (const char *restrict name, struct el *restrict e)
+{
+	int rc = conv_str(name, e);
+	int id;
+
+	ns_flags = 0;
+	id = get_ns_id(name);
+	if (id == -1)
+		return 0;
+	ns_flags |= (1 << id);
+
+	return rc;
+}
+
 static int match_numlist (long value, const struct el *restrict list)
 {
 	int found = 0;
@@ -350,6 +375,21 @@ static int match_strlist (const char *restrict value, const struct el *restrict
 	return found;
 }
 
+static int match_ns (const proc_t *task, const proc_t *ns_task)
+{
+	int found = 1;
+	int i;
+
+	for (i = 0; i < NUM_NS; i++) {
+		if (ns_flags & (1 << i)) {
+			if (task->ns[i] != ns_task->ns[i])
+				found = 0;
+		}
+	}
+
+	return found;
+}
+
 static void output_numlist (const struct el *restrict list, int num)
 {
 	int i;
@@ -386,6 +426,8 @@ static PROCTAB *do_openproc (void)
 		flags |= PROC_FILLSTAT;
 	if (!(flags & PROC_FILLSTAT))
 		flags |= PROC_FILLSTATUS;  /* FIXME: need one, and PROC_FILLANY broken */
+	if (opt_ns_pid)
+		flags |= PROC_FILLNS;
 	if (opt_euid && !opt_negate) {
 		int num = opt_euid[0].num;
 		int i = num;
@@ -442,6 +484,7 @@ static struct el * select_procs (int *num)
 	char cmdline[CMDSTRSIZE];
 	char cmdsearch[CMDSTRSIZE];
 	char cmdoutput[CMDSTRSIZE];
+	proc_t ns_task;
 
 	ptp = do_openproc();
 	preg = do_regcomp();
@@ -451,7 +494,12 @@ static struct el * select_procs (int *num)
 
 	if (opt_newest) saved_pid = 0;
 	if (opt_oldest) saved_pid = INT_MAX;
-
+	if (opt_ns_pid && ns_read(opt_ns_pid, &ns_task)) {
+		fputs(_("Error reading reference namespace information\n"),
+		      stderr);
+		exit (EXIT_FATAL);
+	}
+	
 	memset(&task, 0, sizeof (task));
 	while(readproc(ptp, &task)) {
 		int match = 1;
@@ -476,6 +524,8 @@ static struct el * select_procs (int *num)
 			match = 0;
 		else if (opt_sid && ! match_numlist (task.session, opt_sid))
 			match = 0;
+		else if (opt_ns_pid && ! match_ns (&task, &ns_task))
+			match = 0;
 		else if (opt_term) {
 			if (task.tty == 0) {
 				match = 0;
@@ -622,7 +672,9 @@ static void parse_opts (int argc, char **argv)
 	int criteria_count = 0;
 
 	enum {
-		SIGNAL_OPTION = CHAR_MAX + 1
+		SIGNAL_OPTION = CHAR_MAX + 1,
+		NS_OPTION,
+		NSLIST_OPTION,
 	};
 	static const struct option longopts[] = {
 		{"signal", required_argument, NULL, SIGNAL_OPTION},
@@ -646,6 +698,8 @@ static void parse_opts (int argc, char **argv)
 		{"pidfile", required_argument, NULL, 'F'},
 		{"logpidfile", no_argument, NULL, 'L'},
 		{"echo", no_argument, NULL, 'e'},
+		{"ns", required_argument, NULL, NS_OPTION},
+		{"nslist", required_argument, NULL, NSLIST_OPTION},
 		{"help", no_argument, NULL, 'h'},
 		{"version", no_argument, NULL, 'V'},
 		{NULL, 0, NULL, 0}
@@ -792,6 +846,17 @@ static void parse_opts (int argc, char **argv)
 			break;
 /*		case 'z':   / * Solaris: match by zone ID * /
  *			break; */
+		case NS_OPTION:
+			opt_ns_pid = atoi(optarg);
+			if (opt_ns_pid == 0)
+				usage (opt);
+			++criteria_count;
+			break;
+		case NSLIST_OPTION:
+			opt_nslist = split_list (optarg, conv_ns);
+			if (opt_nslist == NULL)
+				usage (opt);
+			break;
 		case 'h':
 			usage (opt);
 			break;
diff --git a/proc/libprocps.sym b/proc/libprocps.sym
index 51d53c9..d4f692e 100644
--- a/proc/libprocps.sym
+++ b/proc/libprocps.sym
@@ -11,6 +11,8 @@ global:
 	escaped_copy;
 	free_slabinfo;
 	freeproc;
+	get_ns_id;
+	get_ns_name;
 	get_pid_digits;
 	get_slabinfo;
 	getbtime;
diff --git a/proc/readproc.c b/proc/readproc.c
index 11f0898..05d0189 100644
--- a/proc/readproc.c
+++ b/proc/readproc.c
@@ -457,6 +457,51 @@ static void oomadj2proc(const char* S, proc_t *restrict P)
 #endif
 ///////////////////////////////////////////////////////////////////////
 
+static ino_t _ns2proc(unsigned pid, const char *ns)
+{
+    struct stat s;
+    char filename[40];
+
+    snprintf(filename, sizeof(filename), "/proc/%i/ns/%s", pid, ns);
+
+    if (stat(filename, &s) == -1)
+        return 0;
+
+    return s.st_ino;
+}
+
+static const char *ns_names[] = {
+    [IPCNS] = "ipc",
+    [MNTNS] = "mnt",
+    [NETNS] = "net",
+    [PIDNS] = "pid",
+    [USERNS] = "user",
+    [UTSNS] = "uts",
+};
+
+const char *get_ns_name(int id) {
+    if (id >= NUM_NS)
+        return NULL;
+    return ns_names[id];
+}
+
+int get_ns_id(const char *name) {
+    int i;
+
+    for (i = 0; i < NUM_NS; i++)
+        if (!strcmp(ns_names[i], name))
+            return i;
+    return -1;
+}
+
+static void ns2proc(proc_t *restrict P) {
+    int i;
+
+    for (i = 0; i < NUM_NS; i++)
+        P->ns[i] = _ns2proc(P->tgid, ns_names[i]);
+}
+///////////////////////////////////////////////////////////////////////
+
 
 // Reads /proc/*/stat files, being careful not to trip over processes with
 // names like ":-) 1 2 3 4 5 6".
@@ -757,6 +802,7 @@ static proc_t* simple_readproc(PROCTAB *restrict const PT, proc_t *restrict cons
     static struct stat sb;     // stat() buffer
     char *restrict const path = PT->path;
     unsigned flags = PT->flags;
+    int i;
 
     if (unlikely(stat(path, &sb) == -1))        /* no such dirent (anymore) */
         goto next_proc;
@@ -844,6 +890,12 @@ static proc_t* simple_readproc(PROCTAB *restrict const PT, proc_t *restrict cons
     }
 #endif
 
+    if (unlikely(flags & PROC_FILLNS))		// read /proc/#/ns/*
+        ns2proc(p);
+    else
+        for (i = 0; i < NUM_NS; i++)
+             p->ns[i] = 0;
+
     return p;
 next_proc:
     return NULL;
@@ -862,6 +914,7 @@ static proc_t* simple_readtask(PROCTAB *restrict const PT, const proc_t *restric
     static struct utlbuf_s ub = { NULL, 0 };    // buf for stat,statm,status
     static struct stat sb;     // stat() buffer
     unsigned flags = PT->flags;
+    int i;
 
     if (unlikely(stat(path, &sb) == -1))        /* no such dirent (anymore) */
         goto next_task;
@@ -974,6 +1027,11 @@ static proc_t* simple_readtask(PROCTAB *restrict const PT, const proc_t *restric
             oomadj2proc(ub.buf, t);
     }
 #endif
+    if (unlikely(flags & PROC_FILLNS))
+        ns2proc(t);
+    else
+        for (i = 0; i < NUM_NS; i++)
+            t->ns[i] = 0;
 
     return t;
 next_task:
diff --git a/proc/readproc.h b/proc/readproc.h
index fb83dda..643fb26 100644
--- a/proc/readproc.h
+++ b/proc/readproc.h
@@ -31,6 +31,18 @@ EXTERN_C_BEGIN
 // neither tgid nor tid seemed correct. (in other words, FIXME)
 #define XXXID tid
 
+#define NUM_NS 6
+enum ns_type {
+    IPCNS = 0,
+    MNTNS,
+    NETNS,
+    PIDNS,
+    USERNS,
+    UTSNS
+};
+extern const char *get_ns_name(int id);
+extern int get_ns_id(const char *name);
+
 // Basic data structure which holds all information we can get about a process.
 // (unless otherwise specified, fields are read from /proc/#/stat)
 //
@@ -157,6 +169,8 @@ typedef struct proc_t {
         oom_score,      // oom_score       (badness for OOM killer)
         oom_adj;        // oom_adj         (adjustment to OOM score)
 #endif
+    ino_t
+        ns[NUM_NS];     // ns/*            inode number of /proc/<pid>/ns/*
 } proc_t;
 
 // PROCTAB: data structure holding the persistent information readproc needs
@@ -266,6 +280,7 @@ extern proc_t * get_proc_stats(pid_t pid, proc_t *p);
 #define PROC_FILLCGROUP      0x0200 // alloc and fill in `cgroup`
 #define PROC_FILLSUPGRP      0x0400 // resolve supplementary group id -> group name
 #define PROC_FILLOOM         0x0800 // fill in proc_t oom_score and oom_adj
+#define PROC_FILLNS          0x8000 // fill in proc_t namespace information
 
 #define PROC_LOOSE_TASKS     0x2000 // treat threads as if they were processes
 
diff --git a/ps/output.c b/ps/output.c
index d457a89..2e9056e 100644
--- a/ps/output.c
+++ b/ps/output.c
@@ -139,6 +139,13 @@ static int sr_ ## NAME (const proc_t* P, const proc_t* Q) { \
     return 0; \
 }
 
+#define CMP_NS(NAME, ID) \
+static int sr_ ## NAME (const proc_t* P, const proc_t* Q) { \
+    if (P->ns[ID] < Q->ns[ID]) return -1; \
+    if (P->ns[ID] > Q->ns[ID]) return  1; \
+    return 0; \
+}
+
 CMP_INT(rtprio)
 CMP_SMALL(sched)
 CMP_INT(cutime)
@@ -216,6 +223,13 @@ CMP_SMALL(state)
 CMP_COOKED_TIME(time)
 CMP_COOKED_TIME(etime)
 
+CMP_NS(ipcns, IPCNS);
+CMP_NS(mntns, MNTNS);
+CMP_NS(netns, NETNS);
+CMP_NS(pidns, PIDNS);
+CMP_NS(userns, USERNS);
+CMP_NS(utsns, UTSNS);
+
 /* approximation to: kB of address space that could end up in swap */
 static int sr_swapable(const proc_t* P, const proc_t* Q) {
   unsigned long p_swapable = P->vm_data + P->vm_stack;
@@ -1279,6 +1293,22 @@ fail:
 }
 
 #endif
+/************************ Linux namespaces ******************************/
+
+#define _pr_ns(NAME, ID)\
+static int pr_##NAME(char *restrict const outbuf, const proc_t *restrict const pp) {\
+  if (pp->ns[ID])\
+    return snprintf(outbuf, COLWID, "%li", pp->ns[ID]);\
+  else\
+    return snprintf(outbuf, COLWID, "-");\
+}
+_pr_ns(ipcns, IPCNS);
+_pr_ns(mntns, MNTNS);
+_pr_ns(netns, NETNS);
+_pr_ns(pidns, PIDNS);
+_pr_ns(userns, USERNS);
+_pr_ns(utsns, UTSNS);
+
 /****************** FLASK & seLinux security stuff **********************/
 // move the bulk of this to libproc sometime
 
@@ -1440,6 +1470,7 @@ static int pr_t_left2(char *restrict const outbuf, const proc_t *restrict const
 #define USR PROC_FILLUSR     /* uid_t -> user names */
 #define GRP PROC_FILLGRP     /* gid_t -> group names */
 #define WCH PROC_FILLWCHAN   /* do WCHAN lookup */
+#define NS  PROC_FILLNS      /* read namespace information */
 
 #define SGRP PROC_FILLSTATUS | PROC_FILLSUPGRP  /* supgid -> supgrp (names) */
 #define CGRP PROC_FILLCGROUP | PROC_EDITCGRPCVT /* read cgroup */
@@ -1528,6 +1559,7 @@ static const format_struct format_array[] = {
 {"inblk",     "INBLK",   pr_nop,      sr_nop,     5,   0,    BSD, AN|RIGHT}, /*inblock*/
 {"inblock",   "INBLK",   pr_nop,      sr_nop,     5,   0,    DEC, AN|RIGHT}, /*inblk*/
 {"intpri",    "PRI",     pr_opri,     sr_priority, 3,  0,    HPU, TO|RIGHT},
+{"ipcns",     "IPCNS",   pr_ipcns,    sr_ipcns,  10,  NS,    LNX, ET|RIGHT},
 {"jid",       "JID",     pr_nop,      sr_nop,     1,   0,    SGI, PO|RIGHT},
 {"jobc",      "JOBC",    pr_nop,      sr_nop,     4,   0,    XXX, AN|RIGHT},
 {"ktrace",    "KTRACE",  pr_nop,      sr_nop,     8,   0,    BSD, AN|RIGHT},
@@ -1560,9 +1592,11 @@ static const format_struct format_array[] = {
 {"majflt",    "MAJFLT",  pr_majflt,   sr_maj_flt, 6,   0,    XXX, AN|RIGHT},
 {"min_flt",   "MINFL",   pr_minflt,   sr_min_flt, 6,   0,    LNX, AN|RIGHT},
 {"minflt",    "MINFLT",  pr_minflt,   sr_min_flt, 6,   0,    XXX, AN|RIGHT},
+{"mntns",     "MNTNS",   pr_mntns,    sr_mntns,  10,  NS,    LNX, ET|RIGHT},
 {"msgrcv",    "MSGRCV",  pr_nop,      sr_nop,     6,   0,    XXX, AN|RIGHT},
 {"msgsnd",    "MSGSND",  pr_nop,      sr_nop,     6,   0,    XXX, AN|RIGHT},
 {"mwchan",    "MWCHAN",  pr_nop,      sr_nop,     6, WCH,    BSD, TO|WCHAN}, /* mutex (FreeBSD) */
+{"netns",     "NETNS",   pr_netns,    sr_netns,  10,  NS,    LNX, ET|RIGHT},
 {"ni",        "NI",      pr_nice,     sr_nice,    3,   0,    BSD, TO|RIGHT}, /*nice*/
 {"nice",      "NI",      pr_nice,     sr_nice,    3,   0,    U98, TO|RIGHT}, /*ni*/
 {"nivcsw",    "IVCSW",   pr_nop,      sr_nop,     5,   0,    XXX, AN|RIGHT},
@@ -1587,6 +1621,7 @@ static const format_struct format_array[] = {
 {"pgid",      "PGID",    pr_pgid,     sr_pgrp,    5,   0,    U98, PO|PIDMAX|RIGHT},
 {"pgrp",      "PGRP",    pr_pgid,     sr_pgrp,    5,   0,    LNX, PO|PIDMAX|RIGHT},
 {"pid",       "PID",     pr_procs,    sr_procs,   5,   0,    U98, PO|PIDMAX|RIGHT},
+{"pidns",     "PIDNS",   pr_pidns,    sr_pidns,  10,  NS,    LNX, ET|RIGHT},
 {"pmem",      "%MEM",    pr_pmem,     sr_rss,     4,   0,    XXX, PO|RIGHT}, /*%mem*/
 {"poip",      "-",       pr_nop,      sr_nop,     1,   0,    BSD, AN|RIGHT},
 {"policy",    "POL",     pr_class,    sr_sched,   3,   0,    DEC, TO|LEFT},
@@ -1694,10 +1729,12 @@ static const format_struct format_array[] = {
 {"upr",       "UPR",     pr_nop,      sr_nop,     3,   0,    BSD, TO|RIGHT}, /*usrpri*/
 {"uprocp",    "UPROCP",  pr_nop,      sr_nop,     8,   0,    BSD, AN|RIGHT},
 {"user",      "USER",    pr_euser,    sr_euser,   8, USR,    U98, ET|USER}, /* BSD n forces this to UID */
+{"userns",    "USERNS",  pr_userns,   sr_userns, 10,  NS,    LNX, ET|RIGHT},
 {"usertime",  "USER",    pr_nop,      sr_nop,     4,   0,    DEC, ET|RIGHT},
 {"usrpri",    "UPR",     pr_nop,      sr_nop,     3,   0,    DEC, TO|RIGHT}, /*upr*/
 {"util",      "C",       pr_c,        sr_pcpu,    2,   0,    SGI, ET|RIGHT}, // not sure about "C"
 {"utime",     "UTIME",   pr_nop,      sr_utime,   6,   0,    LNx, ET|RIGHT},
+{"utsns",     "UTSNS",   pr_utsns,    sr_utsns,  10,  NS,    LNX, ET|RIGHT},
 #ifdef WITH_SYSTEMD
 {"uunit",     "UUNIT",   pr_sd_uunit, sr_nop,    31,   0,    LNX, ET|LEFT},
 #endif
diff --git a/ps/ps.1 b/ps/ps.1
index 6311b48..80e5ce8 100644
--- a/ps/ps.1
+++ b/ps/ps.1
@@ -1299,6 +1299,10 @@ format is displayed.  (alias
 .BR sig_ignore , \ sigignore ).
 T}
 
+ipcns	IPCNS	T{
+Unique inode number describing the namespace the process belongs to. See namespaces(7).
+T}
+
 label	LABEL	T{
 security label, most commonly used for SELinux context data.  This is for
 the
@@ -1335,6 +1339,14 @@ min_flt	MINFLT	T{
 The number of minor page faults that have occurred with this process.
 T}
 
+mntns	MNTNS	T{
+Unique inode number describing the namespace the process belongs to. See namespaces(7).
+T}
+
+netns	NETNS	T{
+Unique inode number describing the namespace the process belongs to. See namespaces(7).
+T}
+
 ni	NI	T{
 nice value. This ranges from 19 (nicest) to \-20 (not nice to others),
 see
@@ -1403,6 +1415,10 @@ a number representing the process ID (alias
 .BR tgid ).
 T}
 
+pidns	PIDNS	T{
+Unique inode number describing the namespace the process belongs to. See namespaces(7).
+T}
+
 pmem	%MEM	T{
 see
 .BR %mem .
@@ -1735,6 +1751,14 @@ see
 .BR euser , \ uname ).
 T}
 
+userns	USERNS	T{
+Unique inode number describing the namespace the process belongs to. See namespaces(7).
+T}
+
+utsns	UTSNS	T{
+Unique inode number describing the namespace the process belongs to. See namespaces(7).
+T}
+
 uunit	UUNIT	T{
 displays systemd user unit which a process belongs to.
 T}
diff --git a/skill.1 b/skill.1
index 9748a1d..8ef7683 100644
--- a/skill.1
+++ b/skill.1
@@ -77,6 +77,13 @@ The next expression is a process ID number.
 .TP
 \fB\-c\fR, \fB\-\-command\fR \fIcommand\fR
 The next expression is a command name.
+.TP
+\fB\-\-ns \fIpid\fR
+Match the processes that belong to the same namespace as pid.
+.TP
+\fB\-\-nslist \fIns,...\fR
+list which namespaces will be considered for the --ns option.
+Available namespaces: ipc, mnt, net, pid, user, uts.
 .PD
 .SH SIGNALS
 The behavior of signals is explained in
diff --git a/skill.c b/skill.c
index fb57305..ab83a03 100644
--- a/skill.c
+++ b/skill.c
@@ -36,6 +36,7 @@
 
 #include "c.h"
 #include "fileutils.h"
+#include "nsutils.h"
 #include "strutils.h"
 #include "nls.h"
 #include "xalloc.h"
@@ -43,6 +44,7 @@
 #include "proc/sig.h"
 #include "proc/devname.h"
 #include "proc/procps.h"	/* char *user_from_uid(uid_t uid) */
+#include "proc/readproc.h"
 #include "proc/version.h"	/* procps_version */
 #include "rpmatch.h"
 
@@ -56,11 +58,14 @@ struct run_time_conf_t {
 	int noaction;
 	int debugging;
 };
-static int tty_count, uid_count, cmd_count, pid_count;
+static int tty_count, uid_count, cmd_count, pid_count, namespace_count;
 static int *ttys;
 static uid_t *uids;
 static const char **cmds;
 static int *pids;
+static char **namespaces;
+static int ns_pid;
+static proc_t ns_task;
 
 #define ENLIST(thing,addme) do{ \
 if(!thing##s) thing##s = xmalloc(sizeof(*thing##s)*saved_argc); \
@@ -85,6 +90,39 @@ static void display_kill_version(void)
 	fprintf(stdout, PROCPS_NG_VERSION);
 }
 
+static int ns_flags = 0x3f;
+static int parse_namespaces(char *optarg)
+{
+	char *ptr = optarg, *tmp;
+	int len, id;
+
+	ns_flags = 0;
+	while (1) {
+		if (strchr(ptr, ',') == NULL) {
+			len = -1;
+			tmp = strdup(ptr);
+		} else {
+			len = strchr(ptr, ',') - ptr;
+			tmp = strndup(ptr, len);
+		}
+
+		id = get_ns_id(tmp);
+		if (id == -1) {
+			fprintf(stderr, "%s is not a valid namespace\n", tmp);
+			free(tmp);
+			return 1;
+		}
+		ns_flags |= (1 << id);
+		ENLIST(namespace, tmp);
+
+		if (len == -1)
+			break;
+
+		ptr+= len + 1;
+	}
+	return 0;
+}
+
 /* kill or nice a process */
 static void hurt_proc(int tty, int uid, int pid, const char *restrict const cmd,
 		      struct run_time_conf_t *run_time)
@@ -131,6 +169,7 @@ static void check_proc(int pid, struct run_time_conf_t *run_time)
 {
 	char buf[128];
 	struct stat statbuf;
+	proc_t task;
 	char *tmp;
 	int tty;
 	int fd;
@@ -183,6 +222,16 @@ static void check_proc(int pid, struct run_time_conf_t *run_time)
 		if (i == -1)
 			goto closure;
 	}
+	if (ns_pid) {
+		if (ns_read(pid, &task))
+			goto closure;
+		for (i = 0; i < NUM_NS; i++) {
+			if (ns_flags & (1 << i)) {
+				if (task.ns[i] != ns_task.ns[i])
+					goto closure;
+			}
+		}
+	}
 	/* This is where we kill/nice something. */
 	/* for debugging purposes?
 	fprintf(stderr, "PID %d, UID %d, TTY %d,%d, COMM %s\n",
@@ -317,6 +366,15 @@ static void __attribute__ ((__noreturn__)) skillsnice_usage(FILE * out)
 		" -t, --tty <tty>          expression is a terminal\n"
 		" -u, --user <username>    expression is a username\n"), out);
 	fputs(USAGE_SEPARATOR, out);
+	fputs(_("Alternatively, expression can be:\n"
+		" --ns <pid>               match the processes that belong to the same\n"
+		"                          namespace as <pid>\n"
+		" --nslist <ns,...>        list which namespaces will be considered for\n"
+		"                          the --ns option.\n"
+		"                          Available namespaces: ipc, mnt, net, pid, user, uts\n"), out);
+
+	fputs(USAGE_SEPARATOR, out);
+	fputs(USAGE_SEPARATOR, out);
 	fputs(USAGE_HELP, out);
 	fputs(USAGE_VERSION, out);
 	if (program == PROG_SKILL) {
@@ -488,6 +546,11 @@ static void skillsnice_parse(int argc,
 	int prino = DEFAULT_NICE;
 	int ch, i;
 
+	enum {
+		NS_OPTION = CHAR_MAX + 1,
+		NSLIST_OPTION,
+	};
+
 	static const struct option longopts[] = {
 		{"command", required_argument, NULL, 'c'},
 		{"debug", no_argument, NULL, 'd'},
@@ -499,6 +562,8 @@ static void skillsnice_parse(int argc,
 		{"table", no_argument, NULL, 'L'},
 		{"tty", required_argument, NULL, 't'},
 		{"user", required_argument, NULL, 'u'},
+		{"ns", required_argument, NULL, NS_OPTION},
+		{"nslist", required_argument, NULL, NSLIST_OPTION},
 		{"verbose", no_argument, NULL, 'v'},
 		{"warnings", no_argument, NULL, 'w'},
 		{"help", no_argument, NULL, 'h'},
@@ -572,6 +637,25 @@ static void skillsnice_parse(int argc,
 				}
 			}
 			break;
+		case NS_OPTION:
+			ns_pid = atoi(optarg);
+			if (ns_pid == 0) {
+				xwarnx(_("invalid pid number %i"), optarg);
+				kill_usage(stderr);
+			}
+			if (ns_read(ns_pid, &ns_task)) {
+				xwarnx(_("error reading reference namespace "
+					 "information"));
+				kill_usage(stderr);
+			}	
+
+			break;
+		case NSLIST_OPTION:
+			if (parse_namespaces(optarg)) {
+				xwarnx(_("invalid namespace list"));
+				kill_usage(stderr);
+			}
+			break;
 		case 'v':
 			run_time->verbose = 1;
 			break;
@@ -605,7 +689,7 @@ static void skillsnice_parse(int argc,
 	}
 
 	/* No more arguments to process. Must sanity check. */
-	if (!tty_count && !uid_count && !cmd_count && !pid_count)
+	if (!tty_count && !uid_count && !cmd_count && !pid_count && !ns_pid)
 		xerrx(EXIT_FAILURE, _("no process selection criteria"));
 	if ((run_time->fast | run_time->interactive | run_time->
 	     verbose | run_time->warnings | run_time->noaction) & ~1)