diff options
| -rw-r--r-- | security/commoncap.c | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/security/commoncap.c b/security/commoncap.c index 7cd61a5..97ac1f1 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -28,6 +28,28 @@ #include <linux/prctl.h> #include <linux/securebits.h> +/* + * If a non-root user executes a setuid-root binary in + * !secure(SECURE_NOROOT) mode, then we raise capabilities. + * However if fE is also set, then the intent is for only + * the file capabilities to be applied, and the setuid-root + * bit is left on either to change the uid (plausible) or + * to get full privilege on a kernel without file capabilities + * support. So in that case we do not raise capabilities. + * + * Warn if that happens, once per boot. + */ +static void warn_setuid_and_fcaps_mixed(char *fname) +{ + static int warned; + if (!warned) { + printk(KERN_INFO "warning: `%s' has both setuid-root and" + " effective capabilities. Therefore not raising all" + " capabilities.\n", fname); + warned = 1; + } +} + int cap_netlink_send(struct sock *sk, struct sk_buff *skb) { NETLINK_CB(skb).eff_cap = current_cap(); @@ -464,6 +486,15 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) if (!issecure(SECURE_NOROOT)) { /* + * If the legacy file capability is set, then don't set privs + * for a setuid root binary run by a non-root user. Do set it + * for a root user just to cause least surprise to an admin. + */ + if (effective && new->uid != 0 && new->euid == 0) { + warn_setuid_and_fcaps_mixed(bprm->filename); + goto skip; + } + /* * To support inheritance of root-permissions and suid-root * executables under compatibility mode, we override the * capability sets for the file. @@ -478,6 +509,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) if (new->euid == 0) effective = true; } +skip: /* Don't let someone trace a set[ug]id/setpcap binary with the revised * credentials unless they have the appropriate permit |
