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From 18f3bad3ba1ffc5a363d188da8b0653f9b527a18 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 5 Jan 2018 13:26:38 +0100
Subject: [PATCH] notify: add new --uid= command
The new --uid= switch allows selecting the UID from which the
notificaiton messages shall originate.
This is primarily useful for testing purposes, but might have other
uses.
(cherry picked from commit 65c6b99094580afa186199d8091cd7536900526c)
Related: #1663143
---
man/systemd-notify.xml | 9 +++++++++
src/notify/notify.c | 39 ++++++++++++++++++++++++++++++++++++---
2 files changed, 45 insertions(+), 3 deletions(-)
diff --git a/man/systemd-notify.xml b/man/systemd-notify.xml
index 46ede1ab8f..4048783611 100644
--- a/man/systemd-notify.xml
+++ b/man/systemd-notify.xml
@@ -106,6 +106,15 @@
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
</varlistentry>
+ <varlistentry>
+ <term><option>--uid=</option><replaceable>USER</replaceable></term>
+
+ <listitem><para>Set the user ID to send the notification from. Takes a UNIX user name or numeric UID. When
+ specified the notification message will be sent with the specified UID as sender, in place of the user the
+ command was invoked as. This option requires sufficient privileges in order to be able manipulate the user
+ identity of the process.</para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><option>--status=</option></term>
diff --git a/src/notify/notify.c b/src/notify/notify.c
index 0d382992a5..659ba7c54b 100644
--- a/src/notify/notify.c
+++ b/src/notify/notify.c
@@ -40,6 +40,8 @@ static pid_t arg_pid = 0;
static const char *arg_status = NULL;
static bool arg_booted = false;
static const char *arg_readahead = NULL;
+static uid_t arg_uid = UID_INVALID;
+static gid_t arg_gid = GID_INVALID;
static void help(void) {
printf("%s [OPTIONS...] [VARIABLE=VALUE...]\n\n"
@@ -47,7 +49,8 @@ static void help(void) {
" -h --help Show this help\n"
" --version Show package version\n"
" --ready Inform the init system about service start-up completion\n"
- " --pid[=PID] Set main pid of daemon\n"
+ " --pid[=PID] Set main PID of daemon\n"
+ " --uid=USER Set user to send from\n"
" --status=TEXT Set status text\n"
" --booted Check if the system was booted up with systemd\n"
" --readahead=ACTION Controls read-ahead operations\n",
@@ -62,7 +65,8 @@ static int parse_argv(int argc, char *argv[]) {
ARG_PID,
ARG_STATUS,
ARG_BOOTED,
- ARG_READAHEAD
+ ARG_READAHEAD,
+ ARG_UID,
};
static const struct option options[] = {
@@ -73,10 +77,11 @@ static int parse_argv(int argc, char *argv[]) {
{ "status", required_argument, NULL, ARG_STATUS },
{ "booted", no_argument, NULL, ARG_BOOTED },
{ "readahead", required_argument, NULL, ARG_READAHEAD },
+ { "uid", required_argument, NULL, ARG_UID },
{}
};
- int c;
+ int c, r;
assert(argc >= 0);
assert(argv);
@@ -122,6 +127,18 @@ static int parse_argv(int argc, char *argv[]) {
arg_readahead = optarg;
break;
+ case ARG_UID: {
+ const char *u = optarg;
+
+ r = get_user_creds(&u, &arg_uid, &arg_gid, NULL, NULL);
+ if (r == -ESRCH) /* If the user doesn't exist, then accept it anyway as numeric */
+ r = parse_uid(u, &arg_uid);
+ if (r < 0)
+ return log_error_errno(r, "Can't resolve user %s: %m", optarg);
+
+ break;
+ }
+
case '?':
return -EINVAL;
@@ -209,6 +226,22 @@ int main(int argc, char* argv[]) {
goto finish;
}
+ /* If this is requested change to the requested UID/GID. Note thta we only change the real UID here, and leave
+ the effective UID in effect (which is 0 for this to work). That's because we want the privileges to fake the
+ ucred data, and sd_pid_notify() uses the real UID for filling in ucred. */
+
+ if (arg_gid != GID_INVALID)
+ if (setregid(arg_gid, (gid_t) -1) < 0) {
+ r = log_error_errno(errno, "Failed to change GID: %m");
+ goto finish;
+ }
+
+ if (arg_uid != UID_INVALID)
+ if (setreuid(arg_uid, (uid_t) -1) < 0) {
+ r = log_error_errno(errno, "Failed to change UID: %m");
+ goto finish;
+ }
+
r = sd_pid_notify(arg_pid ? arg_pid : getppid(), false, n);
if (r < 0) {
log_error_errno(r, "Failed to notify init system: %m");