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Keep CAP_SYS_PTRACE with suid binary

This commit is contained in:
Mykyta Holubakha 2017-01-12 04:25:03 +02:00
parent 527c259d06
commit ea1313d80d
1 changed files with 28 additions and 0 deletions
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28
sway/main.c
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@ -10,6 +10,9 @@
#include <unistd.h>
#include <getopt.h>
#include <sys/capability.h>
#ifdef __linux__
#include <sys/prctl.h>
#endif
#include "sway/extensions.h"
#include "sway/layout.h"
#include "sway/config.h"
@ -289,6 +292,18 @@ int main(int argc, char **argv) {
return 0;
}
#ifdef __linux__
bool suid = false;
if (getuid() != geteuid() || getgid() != getegid()) {
// Retain capabilities after setuid()
if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0)) {
sway_log(L_ERROR, "Cannot keep caps after setuid()");
exit(EXIT_FAILURE);
}
suid = true;
}
#endif
// we need to setup logging before wlc_init in case it fails.
if (debug) {
init_log(L_DEBUG);
@ -311,6 +326,19 @@ int main(int argc, char **argv) {
}
register_extensions();
#ifdef __linux__
if (suid) {
// Drop every cap except CAP_SYS_PTRACE
cap_t caps = cap_init();
cap_value_t keep = CAP_SYS_PTRACE;
if (cap_set_flag(caps, CAP_PERMITTED, 1, &keep, CAP_SET) ||
cap_set_flag(caps, CAP_EFFECTIVE, 1, &keep, CAP_SET) ||
cap_set_proc(caps)) {
sway_log(L_ERROR, "Failed to drop extra capabilities");
exit(EXIT_FAILURE);
}
}
#endif
// handle SIGTERM signals
signal(SIGTERM, sig_handler);