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273d2c67c3
setgroups is unique in not needing a valid mapping before it can be called, in the case of setgroups(0, NULL) which drops all supplemental groups. The design of the user namespace assumes that CAP_SETGID can not actually be used until a gid mapping is established. Therefore add a helper function to see if the user namespace gid mapping has been established and call that function in the setgroups permission check. This is part of the fix for CVE-2014-8989, being able to drop groups without privilege using user namespaces. Cc: stable@vger.kernel.org Reviewed-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
97 lines
2.3 KiB
C
97 lines
2.3 KiB
C
#ifndef _LINUX_USER_NAMESPACE_H
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#define _LINUX_USER_NAMESPACE_H
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#include <linux/kref.h>
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#include <linux/nsproxy.h>
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#include <linux/sched.h>
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#include <linux/err.h>
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#define UID_GID_MAP_MAX_EXTENTS 5
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struct uid_gid_map { /* 64 bytes -- 1 cache line */
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u32 nr_extents;
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struct uid_gid_extent {
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u32 first;
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u32 lower_first;
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u32 count;
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} extent[UID_GID_MAP_MAX_EXTENTS];
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};
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struct user_namespace {
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struct uid_gid_map uid_map;
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struct uid_gid_map gid_map;
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struct uid_gid_map projid_map;
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atomic_t count;
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struct user_namespace *parent;
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int level;
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kuid_t owner;
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kgid_t group;
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unsigned int proc_inum;
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/* Register of per-UID persistent keyrings for this namespace */
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#ifdef CONFIG_PERSISTENT_KEYRINGS
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struct key *persistent_keyring_register;
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struct rw_semaphore persistent_keyring_register_sem;
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#endif
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};
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extern struct user_namespace init_user_ns;
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#ifdef CONFIG_USER_NS
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static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
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{
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if (ns)
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atomic_inc(&ns->count);
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return ns;
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}
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extern int create_user_ns(struct cred *new);
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extern int unshare_userns(unsigned long unshare_flags, struct cred **new_cred);
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extern void free_user_ns(struct user_namespace *ns);
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static inline void put_user_ns(struct user_namespace *ns)
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{
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if (ns && atomic_dec_and_test(&ns->count))
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free_user_ns(ns);
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}
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struct seq_operations;
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extern const struct seq_operations proc_uid_seq_operations;
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extern const struct seq_operations proc_gid_seq_operations;
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extern const struct seq_operations proc_projid_seq_operations;
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extern ssize_t proc_uid_map_write(struct file *, const char __user *, size_t, loff_t *);
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extern ssize_t proc_gid_map_write(struct file *, const char __user *, size_t, loff_t *);
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extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t, loff_t *);
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extern bool userns_may_setgroups(const struct user_namespace *ns);
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#else
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static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
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{
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return &init_user_ns;
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}
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static inline int create_user_ns(struct cred *new)
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{
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return -EINVAL;
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}
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static inline int unshare_userns(unsigned long unshare_flags,
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struct cred **new_cred)
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{
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if (unshare_flags & CLONE_NEWUSER)
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return -EINVAL;
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return 0;
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}
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static inline void put_user_ns(struct user_namespace *ns)
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{
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}
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static inline bool userns_may_setgroups(const struct user_namespace *ns)
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{
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return true;
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}
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#endif
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#endif /* _LINUX_USER_H */
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