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netns-exec: minor style fixes

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- Use inline variable declarations
- Improve messages
- Fix naming: available -> allowed
- Simplify intro comment
This commit is contained in:
Erik Arvstedt 2020-08-21 22:36:07 +02:00
parent 91ebc2d517
commit ed73627e02
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GPG Key ID: 33312B944DD97846
1 changed files with 12 additions and 17 deletions
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29
pkgs/netns-exec/src/main.c
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@ -1,7 +1,4 @@
/* This program must be run with CAP_SYS_ADMIN. This can be achieved for example
* with
* # setcap CAP_SYS_ADMIN+ep ./main
*/
/* This program requires CAP_SYS_ADMIN */
#define _GNU_SOURCE
#include <sched.h>
@ -12,18 +9,17 @@
#include <fcntl.h>
#include <sys/capability.h>
static char *available_netns[] = {
static char *allowed_netns[] = {
"nb-lnd",
"nb-lightning-loop",
"nb-bitcoind",
"nb-liquidd"
};
int check_netns(char *netns) {
int i;
int n_available_netns = sizeof(available_netns) / sizeof(available_netns[0]);
for (i = 0; i < n_available_netns; i++) {
if (strcmp(available_netns[i], netns) == 0) {
int is_netns_allowed(char *netns) {
int n_allowed_netns = sizeof(allowed_netns) / sizeof(allowed_netns[0]);
for (int i = 0; i < n_allowed_netns; i++) {
if (strcmp(allowed_netns[i], netns) == 0) {
return 1;
}
}
@ -35,6 +31,7 @@ void print_capabilities() {
printf("Capabilities: %s\n", cap_to_text(caps, NULL));
cap_free(caps);
}
void drop_capabilities() {
cap_t caps = cap_get_proc();
cap_clear(caps);
@ -43,25 +40,24 @@ void drop_capabilities() {
}
int main(int argc, char **argv) {
int fd;
char netns_path[256];
if (argc < 3) {
printf("usage: %s <netns> <command to execute>\n", argv[0]);
printf("usage: %s <netns> <command>\n", argv[0]);
return 1;
}
if (!check_netns(argv[1])) {
printf("Failed checking %s against available netns.\n", argv[1]);
if (!is_netns_allowed(argv[1])) {
printf("%s is not an allowed netns.\n", argv[1]);
return 1;
}
if(snprintf(netns_path, sizeof(netns_path), "/var/run/netns/%s", argv[1]) < 0) {
printf("Failed concatenating %s to the netns path.\n", argv[1]);
printf("Path length exceeded for netns %s.\n", argv[1]);
return 1;
}
fd = open(netns_path, O_RDONLY);
int fd = open(netns_path, O_RDONLY);
if (fd < 0) {
printf("Failed opening netns %s: %d, %s \n", netns_path, errno, strerror(errno));
return 1;
@ -84,4 +80,3 @@ int main(int argc, char **argv) {
execvp(argv[2], &argv[2]);
return 0;
}