userns: user namespaces: convert all capable checks in kernel/sys.c
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. Feb 15: allow prlimit to current (was regression in previous version) Feb 23: remove debugging printks, uninline set_one_prio_perm and make it bool, and document its return value. Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: Daniel Lezcano <daniel.lezcano@free.fr> Acked-by: David Howells <dhowells@redhat.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Serge E. Hallyn
Linus Torvalds
parent
3263245de4
commit
fc832ad364
1 changed files with 49 additions and 26 deletions
75
kernel/sys.c
75
kernel/sys.c
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@ -119,17 +119,34 @@ EXPORT_SYMBOL(cad_pid);
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void (*pm_power_off_prepare)(void);
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/*
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* Returns true if current's euid is same as p's uid or euid,
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* or has CAP_SYS_NICE to p's user_ns.
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*
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* Called with rcu_read_lock, creds are safe
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*/
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static bool set_one_prio_perm(struct task_struct *p)
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{
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const struct cred *cred = current_cred(), *pcred = __task_cred(p);
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if (pcred->user->user_ns == cred->user->user_ns &&
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(pcred->uid == cred->euid ||
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pcred->euid == cred->euid))
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return true;
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if (ns_capable(pcred->user->user_ns, CAP_SYS_NICE))
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return true;
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return false;
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}
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/*
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* set the priority of a task
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* - the caller must hold the RCU read lock
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*/
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static int set_one_prio(struct task_struct *p, int niceval, int error)
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{
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const struct cred *cred = current_cred(), *pcred = __task_cred(p);
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int no_nice;
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if (pcred->uid != cred->euid &&
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pcred->euid != cred->euid && !capable(CAP_SYS_NICE)) {
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if (!set_one_prio_perm(p)) {
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error = -EPERM;
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goto out;
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}
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@ -506,7 +523,7 @@ SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
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if (rgid != (gid_t) -1) {
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if (old->gid == rgid ||
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old->egid == rgid ||
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capable(CAP_SETGID))
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nsown_capable(CAP_SETGID))
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new->gid = rgid;
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else
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goto error;
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@ -515,7 +532,7 @@ SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
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if (old->gid == egid ||
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old->egid == egid ||
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old->sgid == egid ||
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capable(CAP_SETGID))
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nsown_capable(CAP_SETGID))
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new->egid = egid;
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else
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goto error;
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@ -550,7 +567,7 @@ SYSCALL_DEFINE1(setgid, gid_t, gid)
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old = current_cred();
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retval = -EPERM;
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if (capable(CAP_SETGID))
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if (nsown_capable(CAP_SETGID))
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new->gid = new->egid = new->sgid = new->fsgid = gid;
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else if (gid == old->gid || gid == old->sgid)
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new->egid = new->fsgid = gid;
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@ -617,7 +634,7 @@ SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
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new->uid = ruid;
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if (old->uid != ruid &&
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old->euid != ruid &&
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!capable(CAP_SETUID))
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!nsown_capable(CAP_SETUID))
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goto error;
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}
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@ -626,7 +643,7 @@ SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
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if (old->uid != euid &&
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old->euid != euid &&
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old->suid != euid &&
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!capable(CAP_SETUID))
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!nsown_capable(CAP_SETUID))
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goto error;
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}
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@ -674,7 +691,7 @@ SYSCALL_DEFINE1(setuid, uid_t, uid)
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old = current_cred();
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retval = -EPERM;
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if (capable(CAP_SETUID)) {
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if (nsown_capable(CAP_SETUID)) {
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new->suid = new->uid = uid;
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if (uid != old->uid) {
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retval = set_user(new);
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@ -716,7 +733,7 @@ SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
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old = current_cred();
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retval = -EPERM;
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if (!capable(CAP_SETUID)) {
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if (!nsown_capable(CAP_SETUID)) {
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if (ruid != (uid_t) -1 && ruid != old->uid &&
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ruid != old->euid && ruid != old->suid)
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goto error;
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@ -780,7 +797,7 @@ SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
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old = current_cred();
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retval = -EPERM;
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if (!capable(CAP_SETGID)) {
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if (!nsown_capable(CAP_SETGID)) {
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if (rgid != (gid_t) -1 && rgid != old->gid &&
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rgid != old->egid && rgid != old->sgid)
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goto error;
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@ -840,7 +857,7 @@ SYSCALL_DEFINE1(setfsuid, uid_t, uid)
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if (uid == old->uid || uid == old->euid ||
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uid == old->suid || uid == old->fsuid ||
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capable(CAP_SETUID)) {
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nsown_capable(CAP_SETUID)) {
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if (uid != old_fsuid) {
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new->fsuid = uid;
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if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0)
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@ -873,7 +890,7 @@ SYSCALL_DEFINE1(setfsgid, gid_t, gid)
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if (gid == old->gid || gid == old->egid ||
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gid == old->sgid || gid == old->fsgid ||
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capable(CAP_SETGID)) {
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nsown_capable(CAP_SETGID)) {
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if (gid != old_fsgid) {
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new->fsgid = gid;
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goto change_okay;
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@ -1183,6 +1200,7 @@ SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
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if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
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return -EPERM;
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if (len < 0 || len > __NEW_UTS_LEN)
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return -EINVAL;
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down_write(&uts_sem);
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@ -1230,7 +1248,7 @@ SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len)
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int errno;
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char tmp[__NEW_UTS_LEN];
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if (!capable(CAP_SYS_ADMIN))
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if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
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return -EPERM;
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if (len < 0 || len > __NEW_UTS_LEN)
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return -EINVAL;
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@ -1345,6 +1363,8 @@ int do_prlimit(struct task_struct *tsk, unsigned int resource,
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rlim = tsk->signal->rlim + resource;
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task_lock(tsk->group_leader);
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if (new_rlim) {
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/* Keep the capable check against init_user_ns until
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cgroups can contain all limits */
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if (new_rlim->rlim_max > rlim->rlim_max &&
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!capable(CAP_SYS_RESOURCE))
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retval = -EPERM;
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@ -1388,19 +1408,22 @@ static int check_prlimit_permission(struct task_struct *task)
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{
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const struct cred *cred = current_cred(), *tcred;
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tcred = __task_cred(task);
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if (current != task &&
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(cred->uid != tcred->euid ||
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cred->uid != tcred->suid ||
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cred->uid != tcred->uid ||
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cred->gid != tcred->egid ||
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cred->gid != tcred->sgid ||
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cred->gid != tcred->gid) &&
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!capable(CAP_SYS_RESOURCE)) {
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return -EPERM;
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}
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if (current == task)
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return 0;
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tcred = __task_cred(task);
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if (cred->user->user_ns == tcred->user->user_ns &&
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(cred->uid == tcred->euid &&
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cred->uid == tcred->suid &&
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cred->uid == tcred->uid &&
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cred->gid == tcred->egid &&
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cred->gid == tcred->sgid &&
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cred->gid == tcred->gid))
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return 0;
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if (ns_capable(tcred->user->user_ns, CAP_SYS_RESOURCE))
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return 0;
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return -EPERM;
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}
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SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
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