Hi Mike, Nice additions. Some comments below. On 28 September 2016 at 13:14, Mike Frysinger <vapier@xxxxxxxxxx> wrote: > People sometimes assume that the crash handler runs in the same context > as the crashing process. They would be incorrect :). > --- > man5/core.5 | 30 ++++++++++++++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/man5/core.5 b/man5/core.5 > index c587da5209c8..1c2c6a45c047 100644 > --- a/man5/core.5 > +++ b/man5/core.5 > @@ -208,6 +208,16 @@ 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 current mount > +.BR namespaces (7), Better here would be a reference to the (newish) mount_namespaces(7) page? > +the current working directory (found via > +.BR getcwd (2)), > +and the current > +.BR chroot (2) > +path. > + > Since version 2.4, Linux has also provided > a more primitive method of controlling > the name of the core dump file. > @@ -240,9 +250,29 @@ 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 must live in the root filesystem as it is always executed there. Should the wording here be something like: "The program pathname is interpreted with respect to the initial mount namespace"? > +It is not affected by the > +.BR chroot (2) > +setting 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 > +.I /proc/PID > +.IP * > +The process created runs in the initial namespaces (pid, mount, user, etc...) > +and not in the namespaces of the crashing process. > +You can utilize specifiers like > +.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). Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
