diff options
Diffstat (limited to 'man5/proc_pid.5')
| -rw-r--r-- | man5/proc_pid.5 | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/man5/proc_pid.5 b/man5/proc_pid.5 new file mode 100644 index 0000000..0d8cdaf --- /dev/null +++ b/man5/proc_pid.5 @@ -0,0 +1,73 @@ +.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com> +.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com> +.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org> +.\" +.\" SPDX-License-Identifier: GPL-3.0-or-later +.\" +.TH proc_pid 5 2023-08-15 "Linux man-pages 6.7" +.SH NAME +/proc/pid/, /proc/self/ \- process information +.SH DESCRIPTION +.TP +.IR /proc/ pid / +There is a numerical subdirectory for each running process; the +subdirectory is named by the process ID. +Each +.IR /proc/ pid +subdirectory contains the pseudo-files and directories described below. +.IP +The files inside each +.IR /proc/ pid +directory are normally owned by the effective user and +effective group ID of the process. +However, as a security measure, the ownership is made +.I root:root +if the process's "dumpable" attribute is set to a value other than 1. +.IP +Before Linux 4.11, +.\" commit 68eb94f16227336a5773b83ecfa8290f1d6b78ce +.I root:root +meant the "global" root user ID and group ID +(i.e., UID 0 and GID 0 in the initial user namespace). +Since Linux 4.11, +if the process is in a noninitial user namespace that has a +valid mapping for user (group) ID 0 inside the namespace, then +the user (group) ownership of the files under +.IR /proc/ pid +is instead made the same as the root user (group) ID of the namespace. +This means that inside a container, +things work as expected for the container "root" user. +.IP +The process's "dumpable" attribute may change for the following reasons: +.RS +.IP \[bu] 3 +The attribute was explicitly set via the +.BR prctl (2) +.B PR_SET_DUMPABLE +operation. +.IP \[bu] +The attribute was reset to the value in the file +.I /proc/sys/fs/suid_dumpable +(described below), for the reasons described in +.BR prctl (2). +.RE +.IP +Resetting the "dumpable" attribute to 1 reverts the ownership of the +.IR /proc/ pid /* +files to the process's effective UID and GID. +Note, however, that if the effective UID or GID is subsequently modified, +then the "dumpable" attribute may be reset, as described in +.BR prctl (2). +Therefore, it may be desirable to reset the "dumpable" attribute +.I after +making any desired changes to the process's effective UID or GID. +.TP +.I /proc/self/ +This directory refers to the process accessing the +.I /proc +filesystem, +and is identical to the +.I /proc +directory named by the process ID of the same process. +.SH SEE ALSO +.BR proc (5) |