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c5b9590287
The automatic initialization cannot be part of the main shared library, because there is no thread-safe way to change the environ global variable. This is not a problem if the initializaion happens just at program load time, but becomes one if the shared library is directly or indirectly dlopen()ed during the execution of the program, which could have either kept references to the old environ or could change it in some other thread. This has been observed for example on systems using Samba NSS modules. To avoid any other possible fallout, the constructor is split into a new static library that needs to be linked explicitly into programs using setproctitle(). As an additional safety measure the pkg-config linker flags will mark the program as not allowing to be dlopen()ed so that we avoid the problem described above. Reported-by: Jan Alexander Steffens (heftig) <jan.steffens@gmail.com> Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=66679
141 lines
3.7 KiB
Groff
141 lines
3.7 KiB
Groff
.\" Copyright (c) 1995 Peter Wemm <peter@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, is permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice immediately at the beginning of the file, without modification,
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.\" this list of conditions, and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. This work was done expressly for inclusion into FreeBSD. Other use
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.\" is permitted provided this notation is included.
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.\" 4. Absolutely no warranty of function or purpose is made by the author
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.\" Peter Wemm.
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.\" 5. Modifications may be freely made to this file providing the above
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.\" conditions are met.
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.\"
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.\" $FreeBSD$
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.\"
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.\" The following requests are required for all man pages.
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.Dd December 16, 1995
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.Dt SETPROCTITLE 3
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.Os
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.Sh NAME
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.Nm setproctitle
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.Nd set process title
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.Sh LIBRARY
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.ds str-Lb-libbsd Utility functions from BSD systems (libbsd, \-lbsd)
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.Lb libbsd
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.Sh SYNOPSIS
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.In sys/types.h
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.In bsd/unistd.h
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.Ft void
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.Fn setproctitle_init "int argc" "char *argv[]" "char *envp[]"
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.Ft void
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.Fn setproctitle "const char *fmt" "..."
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.Sh DESCRIPTION
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The
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.Fn setproctitle
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library routine sets the process title that appears on the
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.Xr ps 1
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command.
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.Pp
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The
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.Fn setproctitle_init
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library routine only needs to be called (before any call to
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.Fn setproctitle
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and with
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.Fn main
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arguments), if the automatic constructor support has not
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been linked in through the libbsd-ctor pkg-config file.
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.Pp
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The title is set from the executable's name, followed by the
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result of a
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.Xr printf 3
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style expansion of the arguments as specified by the
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.Va fmt
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argument.
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If the
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.Va fmt
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argument begins with a
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.Dq -
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character, the executable's name is skipped.
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.Pp
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If
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.Va fmt
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is NULL, the process title is restored.
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.Sh EXAMPLES
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To set the title on a daemon to indicate its activity:
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.Bd -literal -offset indent
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setproctitle("talking to %s", inet_ntoa(addr));
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.Ed
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.Sh SEE ALSO
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.Xr ps 1 ,
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.Xr w 1 ,
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.Xr kvm 3 ,
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.Xr kvm_getargv 3 ,
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.Xr printf 3
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.Sh STANDARDS
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The
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.Fn setproctitle
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function
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is implicitly non-standard.
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Other methods of causing the
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.Xr ps 1
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command line to change, including copying over the argv[0] string are
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also implicitly non-portable.
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It is preferable to use an operating system
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supplied
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.Fn setproctitle
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if present.
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.Pp
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Unfortunately, it is possible that there are other calling conventions
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to other versions of
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.Fn setproctitle ,
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although none have been found by the author as yet.
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This is believed to be
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the predominant convention.
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.Pp
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It is thought that the implementation is compatible with other systems,
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including
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.Nx
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and
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.Bsx .
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.Sh HISTORY
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The
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.Fn setproctitle
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function
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first appeared in
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.Fx 2.2 .
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Other operating systems have
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similar functions.
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.Pp
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The
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.Fn setproctitle_init
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function is a libbsd extension not present on the BSDs, avoid using it
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in portable code.
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.Sh AUTHORS
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.An -nosplit
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.An Peter Wemm Aq peter@FreeBSD.org
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stole the idea from the
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.Sy "Sendmail 8.7.3"
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source code by
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.An Eric Allman Aq eric@sendmail.org .
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.Sh BUGS
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Never pass a string with user-supplied data as a format without using
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.Ql %s .
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An attacker can put format specifiers in the string to mangle your stack,
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leading to a possible security hole.
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This holds true even if the string was built using a function like
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.Fn snprintf ,
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as the resulting string may still contain user-supplied conversion specifiers
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for later interpolation by
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.Fn setproctitle .
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.Pp
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Always use the proper secure idiom:
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.Pp
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.Dl setproctitle("%s", string);
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