From: Jeffrey Walton <noloader@gmail.com>
To: libc-help <libc-help@sourceware.org>
Subject: Re: definitions of uid and euid
Date: Tue, 2 Feb 2021 20:49:05 -0500 [thread overview]
Message-ID: <CAH8yC8=5hAqxk55TOo0M8_vp0viR0uVd6_YevfZWejDc1EWeoQ@mail.gmail.com> (raw)
In-Reply-To: <CABrM6wkBrkz1DiyBWAqK=Nqj8e3=bs=NurR-eK7RF4Y6Ob_idA@mail.gmail.com>
On Tue, Feb 2, 2021 at 12:22 PM Peng Yu via Libc-help
<libc-help@sourceware.org> wrote:
>
> `man getuid` says the following without explaining what real user ID
> and effective user ID are.
>
> - getuid() returns the real user ID of the calling process.
> - geteuid() returns the effective user ID of the calling process.
>
> Could anybody explain the definitions of uid and euid, and provide a
> minimum working example demonstrating when they are different? Thanks.
Also see Chen, Wagner and Dean's
https://www.usenix.org/conference/11th-usenix-security-symposium/setuid-demystified:
Access control in Unix systems is mainly based on
user IDs, yet the system calls that modify user IDs
(uid-setting system calls), such as setuid, are poorly
designed, insufficiently documented, and widely
misunderstood and misused. This has caused many
security vulnerabilities in application programs.
...
Jeff
next prev parent reply other threads:[~2021-02-03 1:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 17:04 Peng Yu
2021-02-02 17:54 ` Paul Smith
2021-02-03 1:49 ` Jeffrey Walton [this message]
2021-02-03 3:24 ` Peng Yu
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