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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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2813893f8b
There are a lot of embedded systems that run most or all of their functionality in init, running as root:root. For these systems, supporting multiple users is not necessary. This patch adds a new symbol, CONFIG_MULTIUSER, that makes support for non-root users, non-root groups, and capabilities optional. It is enabled under CONFIG_EXPERT menu. When this symbol is not defined, UID and GID are zero in any possible case and processes always have all capabilities. The following syscalls are compiled out: setuid, setregid, setgid, setreuid, setresuid, getresuid, setresgid, getresgid, setgroups, getgroups, setfsuid, setfsgid, capget, capset. Also, groups.c is compiled out completely. In kernel/capability.c, capable function was moved in order to avoid adding two ifdef blocks. This change saves about 25 KB on a defconfig build. The most minimal kernels have total text sizes in the high hundreds of kB rather than low MB. (The 25k goes down a bit with allnoconfig, but not that much. The kernel was booted in Qemu. All the common functionalities work. Adding users/groups is not possible, failing with -ENOSYS. Bloat-o-meter output: add/remove: 7/87 grow/shrink: 19/397 up/down: 1675/-26325 (-24650) [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Iulia Manda <iulia.manda21@gmail.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
191 lines
4.0 KiB
C
191 lines
4.0 KiB
C
#ifndef _LINUX_UIDGID_H
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#define _LINUX_UIDGID_H
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/*
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* A set of types for the internal kernel types representing uids and gids.
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*
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* The types defined in this header allow distinguishing which uids and gids in
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* the kernel are values used by userspace and which uid and gid values are
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* the internal kernel values. With the addition of user namespaces the values
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* can be different. Using the type system makes it possible for the compiler
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* to detect when we overlook these differences.
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*
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*/
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#include <linux/types.h>
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#include <linux/highuid.h>
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struct user_namespace;
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extern struct user_namespace init_user_ns;
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typedef struct {
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uid_t val;
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} kuid_t;
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typedef struct {
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gid_t val;
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} kgid_t;
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#define KUIDT_INIT(value) (kuid_t){ value }
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#define KGIDT_INIT(value) (kgid_t){ value }
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#ifdef CONFIG_MULTIUSER
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static inline uid_t __kuid_val(kuid_t uid)
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{
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return uid.val;
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}
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static inline gid_t __kgid_val(kgid_t gid)
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{
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return gid.val;
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}
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#else
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static inline uid_t __kuid_val(kuid_t uid)
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{
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return 0;
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}
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static inline gid_t __kgid_val(kgid_t gid)
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{
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return 0;
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}
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#endif
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#define GLOBAL_ROOT_UID KUIDT_INIT(0)
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#define GLOBAL_ROOT_GID KGIDT_INIT(0)
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#define INVALID_UID KUIDT_INIT(-1)
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#define INVALID_GID KGIDT_INIT(-1)
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static inline bool uid_eq(kuid_t left, kuid_t right)
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{
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return __kuid_val(left) == __kuid_val(right);
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}
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static inline bool gid_eq(kgid_t left, kgid_t right)
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{
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return __kgid_val(left) == __kgid_val(right);
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}
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static inline bool uid_gt(kuid_t left, kuid_t right)
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{
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return __kuid_val(left) > __kuid_val(right);
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}
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static inline bool gid_gt(kgid_t left, kgid_t right)
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{
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return __kgid_val(left) > __kgid_val(right);
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}
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static inline bool uid_gte(kuid_t left, kuid_t right)
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{
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return __kuid_val(left) >= __kuid_val(right);
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}
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static inline bool gid_gte(kgid_t left, kgid_t right)
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{
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return __kgid_val(left) >= __kgid_val(right);
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}
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static inline bool uid_lt(kuid_t left, kuid_t right)
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{
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return __kuid_val(left) < __kuid_val(right);
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}
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static inline bool gid_lt(kgid_t left, kgid_t right)
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{
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return __kgid_val(left) < __kgid_val(right);
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}
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static inline bool uid_lte(kuid_t left, kuid_t right)
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{
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return __kuid_val(left) <= __kuid_val(right);
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}
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static inline bool gid_lte(kgid_t left, kgid_t right)
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{
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return __kgid_val(left) <= __kgid_val(right);
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}
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static inline bool uid_valid(kuid_t uid)
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{
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return !uid_eq(uid, INVALID_UID);
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}
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static inline bool gid_valid(kgid_t gid)
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{
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return !gid_eq(gid, INVALID_GID);
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}
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#ifdef CONFIG_USER_NS
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extern kuid_t make_kuid(struct user_namespace *from, uid_t uid);
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extern kgid_t make_kgid(struct user_namespace *from, gid_t gid);
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extern uid_t from_kuid(struct user_namespace *to, kuid_t uid);
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extern gid_t from_kgid(struct user_namespace *to, kgid_t gid);
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extern uid_t from_kuid_munged(struct user_namespace *to, kuid_t uid);
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extern gid_t from_kgid_munged(struct user_namespace *to, kgid_t gid);
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static inline bool kuid_has_mapping(struct user_namespace *ns, kuid_t uid)
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{
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return from_kuid(ns, uid) != (uid_t) -1;
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}
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static inline bool kgid_has_mapping(struct user_namespace *ns, kgid_t gid)
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{
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return from_kgid(ns, gid) != (gid_t) -1;
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}
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#else
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static inline kuid_t make_kuid(struct user_namespace *from, uid_t uid)
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{
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return KUIDT_INIT(uid);
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}
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static inline kgid_t make_kgid(struct user_namespace *from, gid_t gid)
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{
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return KGIDT_INIT(gid);
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}
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static inline uid_t from_kuid(struct user_namespace *to, kuid_t kuid)
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{
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return __kuid_val(kuid);
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}
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static inline gid_t from_kgid(struct user_namespace *to, kgid_t kgid)
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{
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return __kgid_val(kgid);
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}
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static inline uid_t from_kuid_munged(struct user_namespace *to, kuid_t kuid)
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{
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uid_t uid = from_kuid(to, kuid);
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if (uid == (uid_t)-1)
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uid = overflowuid;
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return uid;
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}
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static inline gid_t from_kgid_munged(struct user_namespace *to, kgid_t kgid)
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{
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gid_t gid = from_kgid(to, kgid);
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if (gid == (gid_t)-1)
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gid = overflowgid;
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return gid;
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}
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static inline bool kuid_has_mapping(struct user_namespace *ns, kuid_t uid)
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{
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return true;
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}
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static inline bool kgid_has_mapping(struct user_namespace *ns, kgid_t gid)
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{
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return true;
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}
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#endif /* CONFIG_USER_NS */
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#endif /* _LINUX_UIDGID_H */
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