sock_diag.7: ffix: white space tweaks in example program

[thirdparty/man-pages.git] / man5 / core.5

diff --git a/man5/core.5 b/man5/core.5
index f2bfcc18190990e5b761baaced3256633b211a4d..a7b392f72531a8a8f52f52208d88d1ec39c8c930 100644 (file)
--- a/man5/core.5
+++ b/man5/core.5
@@ -22,7 +22,7 @@
 .\" the source, must acknowledge the copyright and authors of this work.
 .\" %%%LICENSE_END
 .\"
-.TH CORE 5 2015-12-05 "Linux" "Linux Programmer's Manual"
+.TH CORE 5 2016-10-08 "Linux" "Linux Programmer's Manual"
 .SH NAME
 core \- core dump file
 .SH DESCRIPTION
@@ -208,6 +208,15 @@ and
 (see below)
 is nonzero, then .PID will be appended to the core filename.
 
+Paths are interpreted according to the settings that are active for the
+crashing process.
+That means the crashing process's mount namespace (see
+.BR mount_namespaces (7)),
+its current working directory (found via
+.BR getcwd (2)),
+and its root directory (see
+.BR chroot (2)).
+
 Since version 2.4, Linux has also provided
 a more primitive method of controlling
 the name of the core dump file.
@@ -240,9 +249,30 @@ The program must be specified using an absolute pathname (or a
 pathname relative to the root directory, \fI/\fP),
 and must immediately follow the '|' character.
 .IP *
+The program pathname is interpreted with respect to the initial mount namespace
+as it is always executed there.
+It is not affected by the settings
+(e.g., root directory, mount namespace, current working directory)
+of the crashing process.
+.IP *
 The process created to run the program runs as user and group
 .IR root .
 .IP *
+Running as
+.I root
+does not confer any exceptional security bypasses.
+Namely, LSMs (e.g., SELinux) are still active and may prevent the handler
+from accessing details about the crashed process via
+.IR /proc/[pid] .
+.IP *
+The process created runs in the initial namespaces (pid, mount, user, etc...)
+and not in the namespaces of the crashing process.
+One can utilize specifiers such as
+.I %P
+to find the right
+.I /proc/[pid]
+directory and probe/enter the crashing process's namespaces if needed.
+.IP *
 Command-line arguments can be supplied to the
 program (since Linux 2.6.24),
 delimited by white space (up to a total line length of 128 bytes).
@@ -257,12 +287,12 @@ in an argument.
 When collecting core dumps via a pipe to a user-space program,
 it can be useful for the collecting program to gather data about
 the crashing process from that process's
-.IR /proc/PID
+.IR /proc/[pid]
 directory.
 In order to do this safely,
 the kernel must wait for the program collecting the core dump to exit,
 so as not to remove the crashing process's
-.IR /proc/PID
+.IR /proc/[pid]
 files prematurely.
 This in turn creates the
 possibility that a misbehaving collecting program can block
@@ -287,7 +317,7 @@ The default value for this file is 0.
 .\"
 .SS Controlling which mappings are written to the core dump
 Since kernel 2.6.23, the Linux-specific
-.IR /proc/PID/coredump_filter
+.IR /proc/[pid]/coredump_filter
 file can be used to control which memory segments are written to the
 core dump file in the event that a core dump is performed for the
 process with the corresponding process ID.