Drop root before binding the UDS socket and change the default UDS
address to follow to location of the server UDS.
Signed-off-by: Miroslav Lichvar <mlich...@redhat.com>
---
pmc.8 | 13 +++++++++++--
pmc.c | 10 ++++++++--
pmc_common.c | 32 ++++++++++++++++++++++++++++++++
3 files changed, 51 insertions(+), 4 deletions(-)
diff --git a/pmc.8 b/pmc.8
index e0ab5ac..c6ee42f 100644
--- a/pmc.8
+++ b/pmc.8
@@ -81,8 +81,9 @@ Specify the boundary hops value in sent messages. The default
is 1.
Specify the domain number in sent messages. The default is 0.
.TP
.BI \-i " interface"
-Specify the network interface. The default is /var/run/pmc.$pid for the Unix
Domain
-Socket transport and eth0 for the other transports.
+Specify the network interface. The default is pmc.$pid for the Unix Domain
+Socket transport and eth0 for the other transports. A relative path of the Unix
+Domain socket is relative to the directory of the server's socket.
.TP
.BI \-s " uds-address"
Specifies the address of the server's UNIX domain socket.
@@ -144,6 +145,14 @@ options. The name of the section is the name of the
configured port (e.g.
.B domainNumber
The domain attribute of the local clock. The default is 0.
+.TP
+.B user
+The name of the user to which should
+.B pmc
+switch in order to drop the root privileges. By default,
+.B pmc
+will keep the identity of the user under which it is started.
+
.SH PORT OPTIONS
.TP
.B transportSpecific
diff --git a/pmc.c b/pmc.c
index 00d6014..194e450 100644
--- a/pmc.c
+++ b/pmc.c
@@ -546,7 +546,7 @@ static void usage(char *progname)
" -f [file] read configuration from 'file'\n"
" -h prints this message and exits\n"
" -i [dev] interface device to use, default 'eth0'\n"
- " for network and '/var/run/pmc.$pid' for UDS.\n"
+ " for network and 'pmc.$pid' for UDS.\n"
" -s [path] server address for UDS, default '/var/run/ptp4l'.\n"
" -t [hex] transport specific field, default 0x0\n"
" -v prints the software version and exits\n"
@@ -680,8 +680,9 @@ int main(int argc, char *argv[])
if (!iface_name) {
if (transport_type == TRANS_UDS) {
+ /* Directory will be copied from ptp4l address */
snprintf(uds_local, sizeof(uds_local),
- "/var/run/pmc.%d", getpid());
+ "pmc.%d", getpid());
iface_name = uds_local;
} else {
iface_name = "eth0";
@@ -695,6 +696,11 @@ int main(int argc, char *argv[])
print_set_syslog(1);
print_set_verbose(1);
+ if (drop_root_privileges(config_get_string(cfg, NULL, "user"))) {
+ config_destroy(cfg);
+ return -1;
+ }
+
pmc = pmc_create(cfg, transport_type, iface_name, boundary_hops,
domain_number, transport_specific, zero_datalen);
if (!pmc) {
diff --git a/pmc_common.c b/pmc_common.c
index 101df55..fc2fbd8 100644
--- a/pmc_common.c
+++ b/pmc_common.c
@@ -18,6 +18,7 @@
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <errno.h>
+#include <libgen.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
@@ -373,11 +374,39 @@ struct pmc {
int zero_length_gets;
};
+static int complete_uds_address(struct config *cfg, const char *iface,
+ char *uds, size_t len)
+{
+ char *dir, buf[MAX_IFNAME_SIZE + 1];
+
+ /* Don't change absolute paths */
+ if (iface[0] == '/') {
+ if (snprintf(uds, len, "%s", iface) >= len) {
+ pr_err("UDS path too long");
+ return -1;
+ }
+ return 0;
+ }
+
+ /* Relative paths are relative to the directory of the server socket */
+ if (snprintf(buf, sizeof(buf), "%s",
+ config_get_string(cfg, NULL,
+ "uds_address")) >= sizeof(buf) ||
+ !(dir = dirname(buf)) ||
+ snprintf(uds, len, "%s/%s", buf, iface) >= len) {
+ pr_err("UDS path too long");
+ return -1;
+ }
+
+ return 0;
+}
+
struct pmc *pmc_create(struct config *cfg, enum transport_type transport_type,
const char *iface_name, UInteger8 boundary_hops,
UInteger8 domain_number, UInteger8 transport_specific,
int zero_datalen)
{
+ char uds[MAX_IFNAME_SIZE + 1];
struct pmc *pmc;
pmc = calloc(1, sizeof *pmc);
@@ -386,6 +415,9 @@ struct pmc *pmc_create(struct config *cfg, enum
transport_type transport_type,
if (transport_type == TRANS_UDS) {
pmc->port_identity.portNumber = getpid();
+ if (complete_uds_address(cfg, iface_name, uds, sizeof(uds)))
+ goto failed;
+ iface_name = uds;
} else {
if (generate_clock_identity(&pmc->port_identity.clockIdentity,
iface_name)) {
--
2.26.3
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