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setreuid.2: Add more detail on POSIX.1 specification for these syscalls 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2009-10-17 07:35:40 +02:00
parent b033d60f29
commit 715e4bec08
1 changed files with 24 additions and 8 deletions
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man2/setreuid.2
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@ -40,7 +40,7 @@
.\" 2004-07-04 by aeb
.\" 2004-05-27 by Michael Kerrisk
.\"
.TH SETREUID 2 2007-07-26 "Linux" "Linux Programmer's Manual"
.TH SETREUID 2 2009-10-17 "Linux" "Linux Programmer's Manual"
.SH NAME
setreuid, setregid \- set real and/or effective user or group ID
.SH SYNOPSIS
@ -68,16 +68,12 @@ Supplying a value of \-1 for either the real or effective user ID forces
the system to leave that ID unchanged.
Unprivileged processes may only set the effective user ID to the real user ID,
the effective user ID or the saved set-user-ID.
the effective user ID, or the saved set-user-ID.
POSIX: It is unspecified whether unprivileged processes may set the
real user ID to the real user ID, the effective user ID or the
saved set-user-ID.
Linux: Unprivileged users may only set the real user ID to
Unprivileged users may only set the real user ID to
the real user ID or the effective user ID.
Linux: If the real user ID is set or the effective user ID is set to a value
If the real user ID is set or the effective user ID is set to a value
not equal to the previous real user ID,
the saved set-user-ID will be set to the new effective user ID.
@ -117,6 +113,26 @@ function calls first appeared in 4.2BSD).
Setting the effective user (group) ID to the
saved set-user-ID (saved set-group-ID) is
possible since Linux 1.1.37 (1.1.38).
POSIX.1 does not specify all of possible ID changes that are permitted
on Linux for an unprivileged process.
For
.BR setreuid (),
the effective user ID can be made the same as the
real user ID or the save set-user-ID,
and it is unspecified whether unprivileged processes may set the
real user ID to the real user ID, the effective user ID, or the
saved set-user-ID.
For
.BR setregid (),
the real group ID can be changed to the value of the saved set-group-ID,
and the effective group ID can be changed to the value of
the real group ID or the saved set-group-ID.
The precise details of what ID changes are permitted vary
across implementations.
POSIX.1 makes no specification about the effect of these calls
on the saved set-user-ID and saved set-group-ID.
.SH "SEE ALSO"
.BR getgid (2),
.BR getuid (2),