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user: simplify login when running with --disable_clonew_newuser by using prctl(PR_SET_SECUREBITS, SECBIT_KEEP_CAPS | SECBIT_NO_SETUID_FIXUP)

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This commit is contained in:
Robert Swiecki 2017-10-01 16:11:46 +02:00
parent be25a24b5b
commit 02951e0ac8
2 changed files with 7 additions and 30 deletions
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23
contain.c
View File

@ -90,29 +90,6 @@ static bool containDropPrivs(struct nsjconf_t *nsjconf)
}
}
if (nsjconf->clone_newuser == false) {
LOG_D("setresgid(%d, %d, %d)", TAILQ_FIRST(&nsjconf->gids)->inside_id,
TAILQ_FIRST(&nsjconf->gids)->inside_id,
TAILQ_FIRST(&nsjconf->gids)->inside_id);
if (syscall(__NR_setresgid, TAILQ_FIRST(&nsjconf->gids)->inside_id,
TAILQ_FIRST(&nsjconf->gids)->inside_id,
TAILQ_FIRST(&nsjconf->gids)->inside_id)
== -1) {
PLOG_E("setresgid(%u)", TAILQ_FIRST(&nsjconf->gids)->inside_id);
return false;
}
LOG_D("setresuid(%d, %d, %d)", TAILQ_FIRST(&nsjconf->uids)->inside_id,
TAILQ_FIRST(&nsjconf->uids)->inside_id,
TAILQ_FIRST(&nsjconf->uids)->inside_id);
if (syscall(__NR_setresuid, TAILQ_FIRST(&nsjconf->uids)->inside_id,
TAILQ_FIRST(&nsjconf->uids)->inside_id,
TAILQ_FIRST(&nsjconf->uids)->inside_id)
== -1) {
PLOG_E("setresuid(%u)", TAILQ_FIRST(&nsjconf->uids)->inside_id);
return false;
}
}
if (capsInitNs(nsjconf) == false) {
return false;
}

14
user.c
View File

@ -24,12 +24,14 @@
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <linux/securebits.h>
#include <pwd.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
@ -264,13 +266,11 @@ bool userInitNsFromChild(struct nsjconf_t * nsjconf)
PLOG_D("setgroups(NULL) failed");
}
/*
* If we don't use CLONE_NEWUSER, then presumably this binary has been run with euid==0, in
* which case we need to avoid calling setuid/setgid, in order to avoid loosing capabilities
* which will be needed for uname/mount/etc.-like syscalls
*/
if (nsjconf->clone_newuser == false) {
return true;
/* Make sure all capabilities are retained after the subsequent setuid/setgid */
if (prctl(PR_SET_SECUREBITS, SECBIT_KEEP_CAPS | SECBIT_NO_SETUID_FIXUP, 0UL, 0UL, 0UL) ==
-1) {
PLOG_W("prctl(PR_SET_KEEPCAPS, 1UL)");
return false;
}
LOG_D("setresgid(%d, %d, %d)", TAILQ_FIRST(&nsjconf->gids)->inside_id,