kernel: provide ksys_*() wrappers for syscalls called by kernel/uid16.c
Using these helpers allows us to avoid the in-kernel calls to these syscalls: sys_setregid(), sys_setgid(), sys_setreuid(), sys_setuid(), sys_setresuid(), sys_setresgid(), sys_setfsuid(), and sys_setfsgid(). The ksys_ prefix denotes that these function are meant as a drop-in replacement for the syscall. In particular, they use the same calling convention. This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
This commit is contained in:
parent
6203deb0a7
commit
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58
kernel/sys.c
58
kernel/sys.c
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@ -69,6 +69,8 @@
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#include <asm/io.h>
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#include <asm/unistd.h>
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#include "uid16.h"
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#ifndef SET_UNALIGN_CTL
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# define SET_UNALIGN_CTL(a, b) (-EINVAL)
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#endif
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@ -340,7 +342,7 @@ out_unlock:
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* operations (as far as semantic preservation is concerned).
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*/
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#ifdef CONFIG_MULTIUSER
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SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
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long __sys_setregid(gid_t rgid, gid_t egid)
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{
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struct user_namespace *ns = current_user_ns();
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const struct cred *old;
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@ -392,12 +394,17 @@ error:
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return retval;
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}
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SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
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{
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return __sys_setregid(rgid, egid);
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}
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/*
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* setgid() is implemented like SysV w/ SAVED_IDS
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*
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* SMP: Same implicit races as above.
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*/
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SYSCALL_DEFINE1(setgid, gid_t, gid)
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long __sys_setgid(gid_t gid)
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{
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struct user_namespace *ns = current_user_ns();
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const struct cred *old;
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@ -429,6 +436,11 @@ error:
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return retval;
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}
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SYSCALL_DEFINE1(setgid, gid_t, gid)
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{
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return __sys_setgid(gid);
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}
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/*
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* change the user struct in a credentials set to match the new UID
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*/
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@ -473,7 +485,7 @@ static int set_user(struct cred *new)
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* 100% compatible with BSD. A program which uses just setuid() will be
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* 100% compatible with POSIX with saved IDs.
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*/
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SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
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long __sys_setreuid(uid_t ruid, uid_t euid)
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{
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struct user_namespace *ns = current_user_ns();
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const struct cred *old;
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@ -533,6 +545,11 @@ error:
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return retval;
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}
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SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
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{
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return __sys_setreuid(ruid, euid);
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}
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/*
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* setuid() is implemented like SysV with SAVED_IDS
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*
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@ -544,7 +561,7 @@ error:
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* will allow a root program to temporarily drop privileges and be able to
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* regain them by swapping the real and effective uid.
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*/
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SYSCALL_DEFINE1(setuid, uid_t, uid)
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long __sys_setuid(uid_t uid)
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{
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struct user_namespace *ns = current_user_ns();
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const struct cred *old;
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@ -586,12 +603,17 @@ error:
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return retval;
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}
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SYSCALL_DEFINE1(setuid, uid_t, uid)
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{
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return __sys_setuid(uid);
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}
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/*
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* This function implements a generic ability to update ruid, euid,
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* and suid. This allows you to implement the 4.4 compatible seteuid().
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*/
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SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
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long __sys_setresuid(uid_t ruid, uid_t euid, uid_t suid)
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{
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struct user_namespace *ns = current_user_ns();
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const struct cred *old;
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@ -656,6 +678,11 @@ error:
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return retval;
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}
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SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
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{
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return __sys_setresuid(ruid, euid, suid);
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}
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SYSCALL_DEFINE3(getresuid, uid_t __user *, ruidp, uid_t __user *, euidp, uid_t __user *, suidp)
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{
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const struct cred *cred = current_cred();
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@ -678,7 +705,7 @@ SYSCALL_DEFINE3(getresuid, uid_t __user *, ruidp, uid_t __user *, euidp, uid_t _
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/*
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* Same as above, but for rgid, egid, sgid.
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*/
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SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
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long __sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid)
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{
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struct user_namespace *ns = current_user_ns();
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const struct cred *old;
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@ -730,6 +757,11 @@ error:
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return retval;
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}
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SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
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{
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return __sys_setresgid(rgid, egid, sgid);
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}
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SYSCALL_DEFINE3(getresgid, gid_t __user *, rgidp, gid_t __user *, egidp, gid_t __user *, sgidp)
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{
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const struct cred *cred = current_cred();
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@ -757,7 +789,7 @@ SYSCALL_DEFINE3(getresgid, gid_t __user *, rgidp, gid_t __user *, egidp, gid_t _
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* whatever uid it wants to). It normally shadows "euid", except when
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* explicitly set by setfsuid() or for access..
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*/
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SYSCALL_DEFINE1(setfsuid, uid_t, uid)
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long __sys_setfsuid(uid_t uid)
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{
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const struct cred *old;
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struct cred *new;
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@ -793,10 +825,15 @@ change_okay:
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return old_fsuid;
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}
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SYSCALL_DEFINE1(setfsuid, uid_t, uid)
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{
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return __sys_setfsuid(uid);
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}
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/*
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* Samma på svenska..
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*/
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SYSCALL_DEFINE1(setfsgid, gid_t, gid)
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long __sys_setfsgid(gid_t gid)
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{
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const struct cred *old;
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struct cred *new;
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@ -830,6 +867,11 @@ change_okay:
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commit_creds(new);
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return old_fsgid;
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}
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SYSCALL_DEFINE1(setfsgid, gid_t, gid)
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{
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return __sys_setfsgid(gid);
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}
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#endif /* CONFIG_MULTIUSER */
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/**
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@ -18,6 +18,8 @@
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#include <linux/uaccess.h>
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#include "uid16.h"
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SYSCALL_DEFINE3(chown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
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{
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return sys_chown(filename, low2highuid(user), low2highgid(group));
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SYSCALL_DEFINE2(setregid16, old_gid_t, rgid, old_gid_t, egid)
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{
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return sys_setregid(low2highgid(rgid), low2highgid(egid));
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return __sys_setregid(low2highgid(rgid), low2highgid(egid));
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}
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SYSCALL_DEFINE1(setgid16, old_gid_t, gid)
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{
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return sys_setgid(low2highgid(gid));
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return __sys_setgid(low2highgid(gid));
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}
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SYSCALL_DEFINE2(setreuid16, old_uid_t, ruid, old_uid_t, euid)
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{
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return sys_setreuid(low2highuid(ruid), low2highuid(euid));
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return __sys_setreuid(low2highuid(ruid), low2highuid(euid));
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}
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SYSCALL_DEFINE1(setuid16, old_uid_t, uid)
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{
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return sys_setuid(low2highuid(uid));
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return __sys_setuid(low2highuid(uid));
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}
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SYSCALL_DEFINE3(setresuid16, old_uid_t, ruid, old_uid_t, euid, old_uid_t, suid)
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{
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return sys_setresuid(low2highuid(ruid), low2highuid(euid),
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return __sys_setresuid(low2highuid(ruid), low2highuid(euid),
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low2highuid(suid));
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}
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SYSCALL_DEFINE3(setresgid16, old_gid_t, rgid, old_gid_t, egid, old_gid_t, sgid)
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{
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return sys_setresgid(low2highgid(rgid), low2highgid(egid),
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return __sys_setresgid(low2highgid(rgid), low2highgid(egid),
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low2highgid(sgid));
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}
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SYSCALL_DEFINE3(getresgid16, old_gid_t __user *, rgidp, old_gid_t __user *, egidp, old_gid_t __user *, sgidp)
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{
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const struct cred *cred = current_cred();
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SYSCALL_DEFINE1(setfsuid16, old_uid_t, uid)
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{
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return sys_setfsuid(low2highuid(uid));
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return __sys_setfsuid(low2highuid(uid));
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}
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SYSCALL_DEFINE1(setfsgid16, old_gid_t, gid)
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{
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return sys_setfsgid(low2highgid(gid));
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return __sys_setfsgid(low2highgid(gid));
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}
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static int groups16_to_user(old_gid_t __user *grouplist,
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14
kernel/uid16.h
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14
kernel/uid16.h
Normal file
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef LINUX_UID16_H
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#define LINUX_UID16_H
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long __sys_setuid(uid_t uid);
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long __sys_setgid(gid_t gid);
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long __sys_setreuid(uid_t ruid, uid_t euid);
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long __sys_setregid(gid_t rgid, gid_t egid);
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long __sys_setresuid(uid_t ruid, uid_t euid, uid_t suid);
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long __sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid);
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long __sys_setfsuid(uid_t uid);
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long __sys_setfsgid(gid_t gid);
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#endif /* LINUX_UID16_H */
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