Hi Mike, Ping! Cheers, Michael On 09/30/2016 10:05 AM, Michael Kerrisk (man-pages) wrote: > 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
