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-rw-r--r--src/Makefile.am3
-rw-r--r--src/com_start.c1
-rw-r--r--src/genrc.825
-rw-r--r--src/genrc.c10
-rw-r--r--src/genrc.h2
-rw-r--r--src/runas.c191
-rw-r--r--src/sentinel.c2
7 files changed, 232 insertions, 2 deletions
diff --git a/src/Makefile.am b/src/Makefile.am
index f78a979..b565303 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -38,3 +38,4 @@ genrc_SOURCES = \
match_regex.c\
- sentinel.c
+ sentinel.c\
+ runas.c
diff --git a/src/com_start.c b/src/com_start.c
index 65c1775..5744e39 100644
--- a/src/com_start.c
+++ b/src/com_start.c
@@ -114,2 +114,3 @@ com_start(void)
argv[2] = genrc_command;
+ runas();
execvp(SHELL, argv);
diff --git a/src/genrc.8 b/src/genrc.8
index f900639..00522ee 100644
--- a/src/genrc.8
+++ b/src/genrc.8
@@ -20,2 +20,3 @@ genrc \- generic system initialization script helper
.nh
+.na
\fBgenrc\fR\
@@ -25,6 +26,9 @@ genrc \- generic system initialization script helper
[\fB\-c\fR \fICOMMAND\fR]\
+ [\fB\-g\fR \fIGROUP\fR[,\fIGROUP\fR...]]\
[\fB\-p\fR \fIPROGRAM\fR]\
[\fB\-t\fR \fISECONDS\fR]\
+ [\fB\-u\fR \fIUSER\fR]\
[\fB\-\-command=\fICOMMAND\fR]\
[\fB\-\-create\-pidfile=\fIPIDFILE\fR]\
+ [\fB\-\-group=\fIGROUP\fR[,\fIGROUP\fR...]]\
[\fB\-\-help\fR]\
@@ -38,2 +42,3 @@ genrc \- generic system initialization script helper
[\fB\-\-timeout=\fISECONDS\fR]\
+ [\fB\-\-user=\fIUSER\fR]\
[\fB\-\-usage\fR]\
@@ -167,2 +172,11 @@ Display a short help list.
.TP
+\fB\-g\fR, \fB\-\-group=\fIGROUP\fR[,\fIGROUP\fR...]
+Run program with this \fIGROUP\fR privileges. If the argument is a
+list of groups, the first group becomes the principal, and the
+rest of them supplementary groups. Each \fIGROUP\fR is either a group
+name or a numeric group number prefixed with a plus sign. Whatever
+notation is used, it must exist in the system group database.
+
+See also the \fB\-\-user\fR option.
+.TP
\fB\-\-no\-reload\fR
@@ -194,2 +208,11 @@ Display a short usage summary.
.TP
+\fB\-u\fR, \fB\-\-user=\fIUSER\fR
+Run with this user privileges. The argument is either a login
+name or a numeric UID prefixed with the plus sign. Whatever form is
+used, it must correspond to a valid user from the system user
+database.
+
+Unless \fB\-\-group\fR option is also given, the primary and
+supplementary groups of \fIUSER\fR will be used.
+.TP
\fB\-\-version\fR
@@ -284,2 +307,4 @@ Influential environment variables and corresponding options:
\fBGENRC_CREATE_PIDFILE=\fINAME\fR \fB\-\-create\-pidfile=\fINAME\fR
+ \fBGENRC_USER=\fINAME\fR \fB\-\-user=\fINAME\fR
+ \fBGENRC_GROUP=\fIGROUPS\fR \fB\-\-group=\fIGROUPS\fR
.fi
diff --git a/src/genrc.c b/src/genrc.c
index 92b0fac..d4904b6 100644
--- a/src/genrc.c
+++ b/src/genrc.c
@@ -45,5 +45,7 @@ struct option longopts[] = {
{ "verbose", no_argument, 0, 'v' },
+ { "user", required_argument, 0, 'u' },
+ { "group", required_argument, 0, 'g' },
{ NULL }
};
-char shortopts[] = "c:hF:P:p:St:v";
+char shortopts[] = "c:hF:g:P:p:St:u:v";
@@ -388,2 +390,5 @@ main(int argc, char **argv)
break;
+ case 'g':
+ setenv("GENRC_GROUP", optarg, 1);
+ break;
case OPT_CREATE_PIDFILE:
@@ -406,2 +411,5 @@ main(int argc, char **argv)
break;
+ case 'u':
+ setenv("GENRC_USER", optarg, 1);
+ break;
case 'v':
diff --git a/src/genrc.h b/src/genrc.h
index a6e81e8..9842016 100644
--- a/src/genrc.h
+++ b/src/genrc.h
@@ -33,2 +33,3 @@ void system_error(int ec, char const *fmt, ...);
#define xstrdup grecs_strdup
+void *x2nrealloc(void *p, size_t *pn, size_t s);
@@ -63,2 +64,3 @@ int pid_is_running(pid_t pid);
+void runas(void);
diff --git a/src/runas.c b/src/runas.c
new file mode 100644
index 0000000..9d2a6c1
--- a/dev/null
+++ b/src/runas.c
@@ -0,0 +1,191 @@
+/* This file is part of genrc
+Copyryght (C) 2018 Sergey Poznyakoff
+License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+*/
+#include "genrc.h"
+#include <pwd.h>
+#include <grp.h>
+
+static void
+addgid(gid_t **pgv, size_t *pgc, size_t *pgi, gid_t gid)
+{
+ gid_t *gv = *pgv;
+ size_t gc = *pgc;
+ size_t gi = *pgi;
+
+ if (gi == gc)
+ gv = x2nrealloc(gv, &gc, sizeof(gv[0]));
+
+ gv[gi++] = gid;
+ *pgv = gv;
+ *pgc = gc;
+ *pgi = gi;
+}
+
+static int
+member(gid_t *gv, size_t gc, gid_t gid)
+{
+ size_t i;
+
+ for (i = 0; i < gc; i++)
+ if (gv[i] == gid)
+ return 1;
+ return 0;
+}
+
+static size_t
+get_user_groups(const char *user, gid_t **pgv, size_t *pgc)
+{
+ struct group *gr;
+ size_t gi = 0;
+
+ setgrent();
+ while ((gr = getgrent())) {
+ char **p;
+ for (p = gr->gr_mem; *p; p++)
+ if (strcmp(*p, user) == 0)
+ addgid(pgv, pgc, &gi, gr->gr_gid);
+ }
+ endgrent();
+ return gi;
+}
+
+static gid_t
+strtogid(char const *str)
+{
+ struct group *gr;
+
+ if (str[0] == '+') {
+ char *end;
+ unsigned long n;
+
+ errno = 0;
+ n = strtoul(str, &end, 10);
+ if (errno || *end) {
+ genrc_error("invalid group name %s", str);
+ exit(1);
+ }
+
+ gr = getgrgid(n);
+ } else
+ gr = getgrnam(str);
+
+ if (!gr) {
+ genrc_error("%s: no such group", str);
+ exit(1);
+ }
+
+ return gr->gr_gid;
+}
+
+void
+runas(void)
+{
+ struct passwd *pw;
+ uid_t uid;
+ gid_t gid;
+ gid_t *gv;
+ size_t gc, gn;
+ char const *runas_user;
+ char const *runas_groups;
+
+ runas_user = getenv("GENRC_USER");
+ runas_groups = getenv("GENRC_GROUP");
+
+ if (!(runas_user || runas_groups))
+ return;
+ if (getuid() != 0) {
+ genrc_error("not root: can't switch to user privileges");
+ exit(1);
+ }
+
+ if (!runas_user) {
+ pw = getpwuid(0);
+ runas_user = "root";
+ } else if (runas_user[0] == '+') {
+ char *end;
+ unsigned long n;
+
+ errno = 0;
+ n = strtoul(runas_user + 1, &end, 10);
+ if (errno || *end) {
+ genrc_error("invalid user name %s", runas_user);
+ exit(1);
+ }
+
+ pw = getpwuid(n);
+ } else
+ pw = getpwnam(runas_user);
+
+ if (!pw) {
+ genrc_error("%s: no such user", runas_user);
+ exit(1);
+ }
+ runas_user = pw->pw_name;
+
+ uid = pw->pw_uid;
+ gid = pw->pw_gid;
+
+ gv = NULL;
+ gc = 0;
+
+ if (runas_groups && runas_groups[0]) {
+ struct wordsplit ws;
+ size_t i;
+
+ ws.ws_delim = ",";
+ ws.ws_error = genrc_error;
+ if (wordsplit(runas_groups, &ws,
+ WRDSF_NOCMD
+ | WRDSF_NOVAR
+ | WRDSF_DELIM
+ | WRDSF_ENOMEMABRT
+ | WRDSF_SHOWERR
+ | WRDSF_ERROR))
+ exit(1);
+
+ if (ws.ws_wordc == 0) {
+ genrc_error("bad group list: '%s'", runas_groups);
+ exit(1);
+ }
+
+ gid = strtogid(ws.ws_wordv[0]);
+ for (i = 1; i < ws.ws_wordc; i++)
+ addgid(&gv, &gc, &gn, strtogid(ws.ws_wordv[i]));
+
+ wordsplit_free(&ws);
+ }
+
+ if (gc == 0) {
+ gn = get_user_groups(runas_user, &gv, &gc);
+ if (!member(gv, gn, gid))
+ addgid(&gv, &gc, &gn, gid);
+ }
+
+ /* Reset group permissions */
+ if (setgroups(gn, gv)) {
+ system_error(errno, "setgroups");
+ exit(1);
+ }
+ free(gv);
+
+ if (gid) {
+ /* Switch to the user's gid. */
+ if (setgid(gid)) {
+ system_error(errno, "setgid(%lu) failed",
+ (unsigned long) gid);
+ exit(1);
+ }
+ }
+
+ /* Now reset uid */
+ if (uid) {
+ if (setuid(uid)) {
+ system_error(errno, "setuid(%lu) failed: %s",
+ (unsigned long) uid);
+ exit(1);
+ }
+ }
+}
diff --git a/src/sentinel.c b/src/sentinel.c
index 1d44763..59b89cc 100644
--- a/src/sentinel.c
+++ b/src/sentinel.c
@@ -151,2 +151,4 @@ start_command(int p[])
+ runas();
+
close(0);

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