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nstree: tighten permission checks for listing

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Even privileged services should not necessarily be able to see other
privileged service's namespaces so they can't leak information to each
other. Use may_see_all_namespaces() helper that centralizes this policy
until the nstree adapts.

Link: https://patch.msgid.link/20260226-work-visibility-fixes-v1-3-d2c2853313bd@kernel.org
Fixes: 76b6f5dfb3 ("nstree: add listns()")
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Cc: stable@kernel.org # v6.19+
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2026-02-26 14:50:11 +01:00
parent d2324a9317
commit 8d76afe84f
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GPG key ID: 91C61BC06578DCA2
1 changed files with 4 additions and 25 deletions
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29
kernel/nstree.c
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@ -515,32 +515,11 @@ static inline bool __must_check ns_requested(const struct klistns *kls,
static inline bool __must_check may_list_ns(const struct klistns *kls,
struct ns_common *ns)
{
if (kls->user_ns) {
if (kls->userns_capable)
return true;
} else {
struct ns_common *owner;
struct user_namespace *user_ns;
owner = ns_owner(ns);
if (owner)
user_ns = to_user_ns(owner);
else
user_ns = &init_user_ns;
if (ns_capable_noaudit(user_ns, CAP_SYS_ADMIN))
return true;
}
if (kls->user_ns && kls->userns_capable)
return true;
if (is_current_namespace(ns))
return true;
if (ns->ns_type != CLONE_NEWUSER)
return false;
if (ns_capable_noaudit(to_user_ns(ns), CAP_SYS_ADMIN))
return true;
return false;
return may_see_all_namespaces();
}
static inline void ns_put(struct ns_common *ns)
@ -600,7 +579,7 @@ static ssize_t do_listns_userns(struct klistns *kls)
ret = 0;
head = &to_ns_common(kls->user_ns)->ns_owner_root.ns_list_head;
kls->userns_capable = ns_capable_noaudit(kls->user_ns, CAP_SYS_ADMIN);
kls->userns_capable = may_see_all_namespaces();
rcu_read_lock();