diff options
| -rw-r--r-- | ChangeLog | 10 | ||||
| -rw-r--r-- | csu/defs.awk | 4 | ||||
| -rw-r--r-- | manual/filesys.texi | 27 |
3 files changed, 26 insertions, 15 deletions
@@ -1,5 +1,15 @@ 1999-09-19 Ulrich Drepper <drepper@cygnus.com> + * manual/filesys.texi (Testing File Access): Correct description of + SUID. + +1999-08025 H.J. Lu <hjl@gnu.org> + + * csu/defs.awk (.end): Only match with leading white spaces. + (.align): Likewise. + +1999-09-19 Ulrich Drepper <drepper@cygnus.com> + * stdlib/isomac.c: Add va_copy to allowed macros. * po/pl.po: Updated. diff --git a/csu/defs.awk b/csu/defs.awk index ac73e1a..a006c98 100644 --- a/csu/defs.awk +++ b/csu/defs.awk @@ -1,5 +1,5 @@ -/\.end/ { need_end = 1 } -/\.align/ { if($2 > max) max = $2; } +/^[ ]*\.end/ { need_end = 1 } +/^[ ]*\.align/ { if($2 > max) max = $2; } END { if(need_end) diff --git a/manual/filesys.texi b/manual/filesys.texi index 728b904..5a3f0c5 100644 --- a/manual/filesys.texi +++ b/manual/filesys.texi @@ -2267,19 +2267,20 @@ The file resides on a read-only file system. @cindex access, testing for @cindex setuid programs and file access -When a program runs as a privileged user, this permits it to access -files off-limits to ordinary users---for example, to modify -@file{/etc/passwd}. Programs designed to be run by ordinary users but -access such files use the setuid bit feature so that they always run -with @code{root} as the effective user ID. - -Since the program runs as @code{root}, it has permission to access -whatever file the user specifies---but usually the desired behavior is -to permit only those files which the user could ordinarily access. - -The program therefore must explicitly check whether @emph{the user} -would have the necessary access to a file, before it reads or writes the -file. +In some situations it is desirable to allow programs to access files or +devices even if this is not possible with the permissions granted to the +user. One possible solution is to set the setuid-bit of the program +file. If such a program is started the @emph{effective} user ID of the +process is changed to that of the owner of the program file. So to +allow write access to files like @file{/etc/passwd}, which normally can +be written only by the super-user, the modifying program will have to be +owned by @code{root} and the setuid-bit must be set. + +But beside the files the program is intended to change the user should +not be allowed to access any file to which s/he would not have access +anyway. The program therefore must explicitly check whether @emph{the +user} would have the necessary access to a file, before it reads or +writes the file. To do this, use the function @code{access}, which checks for access permission based on the process's @emph{real} user ID rather than the |