From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755423Ab1AKGnl (ORCPT ); Tue, 11 Jan 2011 01:43:41 -0500 Received: from 184-106-158-135.static.cloud-ips.com ([184.106.158.135]:40622 "EHLO mail" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755360Ab1AKGna (ORCPT ); Tue, 11 Jan 2011 01:43:30 -0500 Date: Tue, 11 Jan 2011 06:44:49 +0000 From: "Serge E. Hallyn" To: "Serge E. Hallyn" Cc: LSM , James Morris , Kees Cook , containers@lists.linux-foundation.org, kernel list , "Eric W. Biederman" , Alexey Dobriyan , Michael Kerrisk , Bastian Blank Subject: [PATCH 06/08] user namespaces: convert all capable checks in kernel/sys.c Message-ID: <20110111064449.GG27515@mail.hallyn.com> References: <20110111064342.GA27515@mail.hallyn.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110111064342.GA27515@mail.hallyn.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This allows setuid/setgid in containers. It also fixes some corner cases where kernel logic foregoes capability checks when uids are equivalent. The latter will need to be done throughout the whole kernel. Changelog: Jan 11: Use nsown_capable() as suggested by Bastian Blank. Jan 11: Fix logic errors in uid checks pointed out by Bastian. Signed-off-by: Serge E. Hallyn --- kernel/sys.c | 67 +++++++++++++++++++++++++++++++++++---------------------- 1 files changed, 41 insertions(+), 26 deletions(-) diff --git a/kernel/sys.c b/kernel/sys.c index 9b9b03b..b68cd67 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -116,17 +116,29 @@ EXPORT_SYMBOL(cad_pid); void (*pm_power_off_prepare)(void); +/* called with rcu_read_lock, creds are safe */ +static inline int set_one_prio_perm(struct task_struct *p) +{ + const struct cred *cred = current_cred(), *pcred = __task_cred(p); + + if (pcred->user->user_ns == cred->user->user_ns && + (pcred->uid == cred->euid || + pcred->euid == cred->euid)) + return 1; + if (ns_capable(pcred->user->user_ns, CAP_SYS_NICE)) + return 1; + return 0; +} + /* * set the priority of a task * - the caller must hold the RCU read lock */ static int set_one_prio(struct task_struct *p, int niceval, int error) { - const struct cred *cred = current_cred(), *pcred = __task_cred(p); - int no_nice; + int ret, no_nice; - if (pcred->uid != cred->euid && - pcred->euid != cred->euid && !capable(CAP_SYS_NICE)) { + if (!set_one_prio_perm(p)) { error = -EPERM; goto out; } @@ -496,7 +508,7 @@ SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid) if (rgid != (gid_t) -1) { if (old->gid == rgid || old->egid == rgid || - capable(CAP_SETGID)) + nsown_capable(CAP_SETGID)) new->gid = rgid; else goto error; @@ -505,7 +517,7 @@ SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid) if (old->gid == egid || old->egid == egid || old->sgid == egid || - capable(CAP_SETGID)) + nsown_capable(CAP_SETGID)) new->egid = egid; else goto error; @@ -540,7 +552,7 @@ SYSCALL_DEFINE1(setgid, gid_t, gid) old = current_cred(); retval = -EPERM; - if (capable(CAP_SETGID)) + if (nsown_capable(CAP_SETGID)) new->gid = new->egid = new->sgid = new->fsgid = gid; else if (gid == old->gid || gid == old->sgid) new->egid = new->fsgid = gid; @@ -607,7 +619,7 @@ SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid) new->uid = ruid; if (old->uid != ruid && old->euid != ruid && - !capable(CAP_SETUID)) + !nsown_capable(CAP_SETUID)) goto error; } @@ -616,7 +628,7 @@ SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid) if (old->uid != euid && old->euid != euid && old->suid != euid && - !capable(CAP_SETUID)) + !nsown_capable(CAP_SETUID)) goto error; } @@ -664,7 +676,7 @@ SYSCALL_DEFINE1(setuid, uid_t, uid) old = current_cred(); retval = -EPERM; - if (capable(CAP_SETUID)) { + if (nsown_capable(CAP_SETUID)) { new->suid = new->uid = uid; if (uid != old->uid) { retval = set_user(new); @@ -706,7 +718,7 @@ SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid) old = current_cred(); retval = -EPERM; - if (!capable(CAP_SETUID)) { + if (!nsown_capable(CAP_SETUID)) { if (ruid != (uid_t) -1 && ruid != old->uid && ruid != old->euid && ruid != old->suid) goto error; @@ -770,7 +782,7 @@ SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid) old = current_cred(); retval = -EPERM; - if (!capable(CAP_SETGID)) { + if (!nsown_capable(CAP_SETGID)) { if (rgid != (gid_t) -1 && rgid != old->gid && rgid != old->egid && rgid != old->sgid) goto error; @@ -830,7 +842,7 @@ SYSCALL_DEFINE1(setfsuid, uid_t, uid) if (uid == old->uid || uid == old->euid || uid == old->suid || uid == old->fsuid || - capable(CAP_SETUID)) { + nsown_capable(CAP_SETUID)) { if (uid != old_fsuid) { new->fsuid = uid; if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0) @@ -863,7 +875,7 @@ SYSCALL_DEFINE1(setfsgid, gid_t, gid) if (gid == old->gid || gid == old->egid || gid == old->sgid || gid == old->fsgid || - capable(CAP_SETGID)) { + nsown_capable(CAP_SETGID)) { if (gid != old_fsgid) { new->fsgid = gid; goto change_okay; @@ -1220,7 +1232,7 @@ SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len) int errno; char tmp[__NEW_UTS_LEN]; - if (!capable(CAP_SYS_ADMIN)) + if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN)) return -EPERM; if (len < 0 || len > __NEW_UTS_LEN) return -EINVAL; @@ -1335,6 +1347,8 @@ int do_prlimit(struct task_struct *tsk, unsigned int resource, rlim = tsk->signal->rlim + resource; task_lock(tsk->group_leader); if (new_rlim) { + /* Keep the capable check against init_user_ns until + cgroups can contain all limits */ if (new_rlim->rlim_max > rlim->rlim_max && !capable(CAP_SYS_RESOURCE)) retval = -EPERM; @@ -1379,17 +1393,18 @@ static int check_prlimit_permission(struct task_struct *task) const struct cred *cred = current_cred(), *tcred; tcred = __task_cred(task); - if ((cred->uid != tcred->euid || - cred->uid != tcred->suid || - cred->uid != tcred->uid || - cred->gid != tcred->egid || - cred->gid != tcred->sgid || - cred->gid != tcred->gid) && - !capable(CAP_SYS_RESOURCE)) { - return -EPERM; - } - - return 0; + if (cred->user->user_ns == tcred->user->user_ns && + (cred->uid == tcred->euid && + cred->uid == tcred->suid && + cred->uid == tcred->uid && + cred->gid == tcred->egid && + cred->gid == tcred->sgid && + cred->gid == tcred->gid)) + return 0; + if (ns_capable(tcred->user->user_ns, CAP_SYS_RESOURCE)) + return 0; + + return -EPERM; } SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource, -- 1.7.0.4