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userns: Convert capabilities related permsion checks 

- Use uid_eq when comparing kuids
  Use gid_eq when comparing kgids
- Use make_kuid(user_ns, 0) to talk about the user_namespace root uid

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2012-02-07 16:45:47 -08:00
parent 9c806aa06f
commit 18815a1808
2 changed files with 28 additions and 16 deletions
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3
fs/open.c
View File

@ -316,7 +316,8 @@ SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
if (!issecure(SECURE_NO_SETUID_FIXUP)) {
/* Clear the capabilities if we switch to a non-root user */
if (override_cred->uid)
kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
if (!uid_eq(override_cred->uid, root_uid))
cap_clear(override_cred->cap_effective);
else
override_cred->cap_effective =

41
security/commoncap.c
View File

@ -472,19 +472,22 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
struct cred *new = bprm->cred;
bool effective, has_cap = false;
int ret;
kuid_t root_uid;
effective = false;
ret = get_file_caps(bprm, &effective, &has_cap);
if (ret < 0)
return ret;
root_uid = make_kuid(new->user_ns, 0);
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 (has_cap && new->uid != 0 && new->euid == 0) {
if (has_cap && !uid_eq(new->uid, root_uid) && uid_eq(new->euid, root_uid)) {
warn_setuid_and_fcaps_mixed(bprm->filename);
goto skip;
}
@ -495,12 +498,12 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
*
* If only the real uid is 0, we do not set the effective bit.
*/
if (new->euid == 0 || new->uid == 0) {
if (uid_eq(new->euid, root_uid) || uid_eq(new->uid, root_uid)) {
/* pP' = (cap_bset & ~0) | (pI & ~0) */
new->cap_permitted = cap_combine(old->cap_bset,
old->cap_inheritable);
}
if (new->euid == 0)
if (uid_eq(new->euid, root_uid))
effective = true;
}
skip:
@ -508,8 +511,8 @@ skip:
/* Don't let someone trace a set[ug]id/setpcap binary with the revised
* credentials unless they have the appropriate permit
*/
if ((new->euid != old->uid ||
new->egid != old->gid ||
if ((!uid_eq(new->euid, old->uid) ||
!gid_eq(new->egid, old->gid) ||
!cap_issubset(new->cap_permitted, old->cap_permitted)) &&
bprm->unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
/* downgrade; they get no more than they had, and maybe less */
@ -544,7 +547,7 @@ skip:
*/
if (!cap_isclear(new->cap_effective)) {
if (!cap_issubset(CAP_FULL_SET, new->cap_effective) ||
new->euid != 0 || new->uid != 0 ||
!uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid) ||
issecure(SECURE_NOROOT)) {
ret = audit_log_bprm_fcaps(bprm, new, old);
if (ret < 0)
@ -569,16 +572,17 @@ skip:
int cap_bprm_secureexec(struct linux_binprm *bprm)
{
const struct cred *cred = current_cred();
kuid_t root_uid = make_kuid(cred->user_ns, 0);
if (cred->uid != 0) {
if (!uid_eq(cred->uid, root_uid)) {
if (bprm->cap_effective)
return 1;
if (!cap_isclear(cred->cap_permitted))
return 1;
}
return (cred->euid != cred->uid ||
cred->egid != cred->gid);
return (!uid_eq(cred->euid, cred->uid) ||
!gid_eq(cred->egid, cred->gid));
}
/**
@ -668,15 +672,21 @@ int cap_inode_removexattr(struct dentry *dentry, const char *name)
*/
static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
{
if ((old->uid == 0 || old->euid == 0 || old->suid == 0) &&
(new->uid != 0 && new->euid != 0 && new->suid != 0) &&
kuid_t root_uid = make_kuid(old->user_ns, 0);
if ((uid_eq(old->uid, root_uid) ||
uid_eq(old->euid, root_uid) ||
uid_eq(old->suid, root_uid)) &&
(!uid_eq(new->uid, root_uid) &&
!uid_eq(new->euid, root_uid) &&
!uid_eq(new->suid, root_uid)) &&
!issecure(SECURE_KEEP_CAPS)) {
cap_clear(new->cap_permitted);
cap_clear(new->cap_effective);
}
if (old->euid == 0 && new->euid != 0)
if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid))
cap_clear(new->cap_effective);
if (old->euid != 0 && new->euid == 0)
if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid))
new->cap_effective = new->cap_permitted;
}
@ -709,11 +719,12 @@ int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
* if not, we might be a bit too harsh here.
*/
if (!issecure(SECURE_NO_SETUID_FIXUP)) {
if (old->fsuid == 0 && new->fsuid != 0)
kuid_t root_uid = make_kuid(old->user_ns, 0);
if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid))
new->cap_effective =
cap_drop_fs_set(new->cap_effective);
if (old->fsuid != 0 && new->fsuid == 0)
if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid))
new->cap_effective =
cap_raise_fs_set(new->cap_effective,
new->cap_permitted);