0001344: Addition of setresuid()/setresgid()/getresuid()/getresgid() - Austin Group Defect Tracker

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ID

Category

Severity

Type

Date Submitted

Last Update

0001344

[1003.1(2008)/Issue 7] System Interfaces

Editorial

Enhancement Request

2020-05-20 10:34

2020-05-21 13:09

Reporter

mkerrisk

View Status

public

Assigned To

ajosey

Priority

normal

Resolution

Open

Status

Under Review

Name

Michael Kerrisk

Organization

man7.org

User Reference

Section

XSH

Page Number

n/a

Line Number

n/a

Interp Status

---

Final Accepted Text

Summary

0001344: Addition of setresuid()/setresgid()/getresuid()/getresgid()

Description

setresuid()/setresgid()/getresuid()/getresgid() are implemented on a number systems including at least Linux, FreeBSD, OpenBSD, and HP-UX. (Notably, they are not present on Solaris, so far as I know.)

Adding these interfaces to POSIX would be valuable for a number of reasons:

* The semantics of the existing APIs for modifying credentials are
problematic. The semantics of setuid()/setgid() depend on whether the
process is privileged, so that the API either changes just the
effective ID, or all of real/effective and saved set IDs. The only
POSIX-specified way to change saved set IDs is to use
setreuid()/setregid(). But those APIs depend on a bizarre rule to
determine whether or not the saved set ID is modified. These sorts of
funny behaviors are invitations for programmers to make mistakes, and
in this case such mistakes have obvious security implications.

* By contrast with the former point, the semantics of the changes made
by setresuid() and setresgid() are simple and transparent: one
argument per credential, with "-1" being used to signify "no change".
No semantics that vary according to whether the process is privileged
and no funny rules.

* getresuid()/getresgid() provide the only means of explicitly
retrieving the save set-UID/GID.

Desired Action

1. Add specifications of setresuid()/setresgid()/getresuid()/getresgid()
2. Add SEE ALSO entries in relevant other pages (getuid(), geteuid(), setuid(), setreuid(), getgid(), getegid(), setgid(), setregid(), <unistd.h>)
3. Add prototypes to <unistd.h>
4. Add to "XSI_USER_GROUPS" in "E.1 Subprofiling Option Groups"(?)

I will attempt 1; presumably 2, 3, 4 can be written up as boilerplate editing directions (which I can attempt, but may need some assistance).

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Relationships

(0004879)
mkerrisk (reporter)
2020-05-21 13:09

On page 448 (<unistd.h> Declarations), after line 15419, insert

int getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid);
int getresuid(uid_t *ruid, uid_t *euid, uid_t *suid);

On page 448 (<unistd.h> Declarations), after line 15443, insert

int setresgid(gid_t rgid, gid_t egid, gid_t sgid);
int setresuid(uid_t ruid, uid_t euid, uid_t suid);

On page 451 (<unistd.h> SEE ALSO) at lines 15579-15581, insert the following
entries into the list in sorted order:

getresgid(), getresuid(), setresgid(), setresuid()

On page 1028 (getegid() SEE ALSO) at line 35033, insert the following
entries into the list in sorted order:

getresgid(), getresuid(), setresgid(), setresuid()

On page 1032 (geteuid() SEE ALSO) at line 35171, insert the following
entries into the list in sorted order:

getresgid(), getresuid(), setresgid(), setresuid()

On page 1033 (getgid() SEE ALSO) at line 35210, insert the following
entries into the list in sorted order:

getresgid(), getresuid(), setresgid(), setresuid()

On page 1104 (getuid() SEE ALSO) at line 37410, insert the following
entries into the list in sorted order:

getresgid(), getresuid(), setresgid(), setresuid()

On page 1890 (setegid() SEE ALSO) at line 61214, insert the following
entries into the list in sorted order:

getresgid(), getresuid(), setresgid(), setresuid()

On page 1893 (seteuid() SEE ALSO) at line 61308, insert the following
entries into the list in sorted order:

getresgid(), getresuid(), setresgid(), setresuid()

On page 1894 (setgid() SEE ALSO) at line 61345, insert the following
entries into the list in sorted order:

getresgid(), getresuid(), setresgid(), setresuid()

On page 1917 (setregid() SEE ALSO) at line 61847, insert the following
entries into the list in sorted order:

getresgid(), getresuid(), setresgid(), setresuid()

On page 1919 (setreuid() SEE ALSO) at line 61908, insert the following
entries into the list in sorted order:

getresgid(), getresuid(), setresgid(), setresuid()

On page 1929 (setuid() SEE ALSO) at line 62155, insert the following
entries into the list in sorted order:

getresgid(), getresuid(), setresgid(), setresuid()

(Depending on whether these APIs should be part of XSI_USER_GROUPS)
On page 3794 (Subprofiling Option Groups) at lines 130234-130234,
insert the following entries into the list in sorted order:

getresgid(), getresuid(), setresgid(), setresuid()

At page 1086, insert the specifications for getresuid() and getresgid():

NAME

getresgid - get real group ID, effective group ID, and saved set-group-ID

SYNOPSIS
#include <unistd.h>

int getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid);
DESCRIPTION

The getresgid() function shall return the calling process's real
group ID, effective group ID, and saved set-group-ID, storing them
in the locations pointed to by, respectively, the arguments rgid,
egid, and sgid.

RETURN VALUE

Upon successful completion, 0 shall be returned. Otherwise, -1
shall be returned and errno set to indicate the error.

ERRORS

No errors are defined.

SEE ALSO

getegid(), geteuid(), getgid(), getresuid(), getuid(), setegid(),
setgid(), seteuid(), setregid(), setresgid(), setresuid(),
setreuid(), setuid()

XBD <sys/types.h>, <unistd.h>

NAME

getresuid - get real user ID, effective user ID, and saved set-user-ID

SYNOPSIS
#include <unistd.h>

int getresuid(uid_t *ruid, uid_t *euid, uid_t *suid);
DESCRIPTION

The getresuid() function shall return the calling process's real
user ID, effective user ID, and saved set-user-ID, storing them in
the locations pointed to by, respectively, the arguments ruid,
euid, and suid.

RETURN VALUE

Upon successful completion, 0 shall be returned. Otherwise, -1
shall be returned and errno set to indicate the error.

ERRORS

No errors are defined.

SEE ALSO

getegid(), geteuid(), getgid(), getresgid(), getuid(), setegid(),
setgid(), seteuid(), setregid(), setresgid(), setresuid(),
setreuid(), setuid()

XBD <sys/types.h>, <unistd.h>

At page 1918, insert the specifications for setresuid() and setresgid():

NAME

setresgid - set real group ID, effective group ID, and saved set-group-ID

SYNOPSIS
#include <unistd.h>

int setresgid(gid_t rgid, gid_t egid, gid_t sgid);
DESCRIPTION

The setresgid() function shall change the calling process's real
group ID, effective group ID, and saved set-group-ID, respectively,
to the values specified by rgid, egid, and sgid.

If one of the arguments is -1, the corresponding group ID shall
not be changed.

Only a process with appropriate privileges can set the real group
ID, effective group ID, and saved set-group-ID to any valid value.

A non-privileged process may set its real group ID, effective
group ID, and saved set-group-ID, each to one of the values that
it currently holds in its real group ID, effective group ID, or
saved set-group-ID.

The real group ID, effective group ID, and saved set-group-ID may
be set to different values in the same call.

RETURN VALUE

Upon successful completion, 0 shall be returned. Otherwise, -1
shall be returned and errno set to indicate the error, and none of
the group IDs shall be changed.

ERRORS

The setresgid() function shall fail if:

[EINVAL]

The value of the rgid, egid, or sgid argument is invalid or out-of-range.

[EPERM]

The calling process does not have appropriate privileges,
and an attempt was made to change the real group ID,
effective group ID, or saved set-group-ID to a value that
is not currently present in one of those IDs.

SEE ALSO

getegid(), geteuid(), getgid(), getresgid(), getresuid(),
getuid(), setegid(), seteuid(), setgid(), setregid(), setresuid(),
setreuid(), setuid()

XBD <sys/types.h>, <unistd.h>

NAME

setresuid - set real user ID, effective user ID, and saved set-user-ID

SYNOPSIS
#include <unistd.h>

int setresuid(uid_t ruid, uid_t euid, uid_t suid);
DESCRIPTION

The setresuid() function shall change the calling process's real
user ID, effective user ID, and saved set-user-ID, respectively,
to the values specified by ruid, euid, and suid.

If one of the arguments is -1, the corresponding user ID shall not
be changed.

Only a process with appropriate privileges can set the real user
ID, effective user ID, and saved set-user-ID to any valid value.

A non-privileged process may set its real user ID, effective user
ID, and saved set-user-ID, each to one of the values that it
currently holds in its real user ID, effective user ID, or saved
set-user-ID.

The real user ID, effective user ID, and saved set-user-ID may be
set to different values in the same call.

RETURN VALUE

Upon successful completion, 0 shall be returned. Otherwise, -1
shall be returned and errno set to indicate the error, and none of
the user IDs shall be changed.

ERRORS

The setresuid() function shall fail if:

[EINVAL]

The value of the ruid, euid, or suid argument is invalid or out-of-range.

[EPERM]

The calling process does not have appropriate privileges,
and an attempt was made to change the real user ID,
effective user ID, or saved set-user-ID to a value that is
not currently present in one of those IDs.

SEE ALSO

getegid(), geteuid(), getgid(), getresgid(), getresuid(),
getuid(), setegid(), seteuid(), setgid(), setregid(), setresgid(),
setreuid(), setuid()

XBD <sys/types.h>, <unistd.h>

Issue History
Date Modified	Username	Field	Change
2020-05-20 10:34	mkerrisk	New Issue
2020-05-20 10:34	mkerrisk	Status	New => Under Review
2020-05-20 10:34	mkerrisk	Assigned To	=> ajosey
2020-05-20 10:34	mkerrisk	Name	=> Michael Kerrisk
2020-05-20 10:34	mkerrisk	Organization	=> man7.org
2020-05-20 10:34	mkerrisk	Section	=> XSH
2020-05-20 10:34	mkerrisk	Page Number	=> n/a
2020-05-20 10:34	mkerrisk	Line Number	=> n/a
2020-05-21 12:51	mkerrisk	Note Added: 0004875
2020-05-21 12:57	mkerrisk	Note Added: 0004876
2020-05-21 12:58	mkerrisk	Note Deleted: 0004875
2020-05-21 12:59	mkerrisk	Note Deleted: 0004876
2020-05-21 12:59	mkerrisk	Note Added: 0004877
2020-05-21 12:59	mkerrisk	Note Deleted: 0004877
2020-05-21 13:02	mkerrisk	Note Added: 0004878
2020-05-21 13:08	mkerrisk	Note Deleted: 0004878
2020-05-21 13:09	mkerrisk	Note Added: 0004879

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