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Remove risky compatability with old kernels

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The badsys() handler for SIGSYS was added as a transtion aid for kernels
lacking sysctl() in 1993.  It is unsafe and unsound so remove it rather
than running the risk of a privilege-dropping system call being silently
omitted.

This partially reverts SCCSID 6.12 (Berkeley) 03/03/93 "add code to
change the system security level".

Reviewed by:	mckusick, imp, kevans
Obtained from:	CheriBSD
MFC after:	1 week
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D26289
This commit is contained in:
Brooks Davis 2020-09-02 21:14:36 +00:00
parent 97bdc65f27
commit a449e81e00
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=365279
1 changed files with 2 additions and 20 deletions
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22
sbin/init/init.c
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@ -106,7 +106,6 @@ static void stall(const char *, ...) __printflike(1, 2);
static void warning(const char *, ...) __printflike(1, 2);
static void emergency(const char *, ...) __printflike(1, 2);
static void disaster(int);
static void badsys(int);
static void revoke_ttys(void);
static int runshutdown(void);
static char *strk(char *);
@ -307,9 +306,8 @@ main(int argc, char *argv[])
* We catch or block signals rather than ignore them,
* so that they get reset on exec.
*/
handle(badsys, SIGSYS, 0);
handle(disaster, SIGABRT, SIGFPE, SIGILL, SIGSEGV, SIGBUS, SIGXCPU,
SIGXFSZ, 0);
handle(disaster, SIGABRT, SIGFPE, SIGILL, SIGSEGV, SIGBUS, SIGSYS,
SIGXCPU, SIGXFSZ, 0);
handle(transition_handler, SIGHUP, SIGINT, SIGEMT, SIGTERM, SIGTSTP,
SIGUSR1, SIGUSR2, SIGWINCH, 0);
handle(alrm_handler, SIGALRM, 0);
@ -506,22 +504,6 @@ emergency(const char *message, ...)
va_end(ap);
}
/*
* Catch a SIGSYS signal.
*
* These may arise if a system does not support sysctl.
* We tolerate up to 25 of these, then throw in the towel.
*/
static void
badsys(int sig)
{
static int badcount = 0;
if (badcount++ < 25)
return;
disaster(sig);
}
/*
* Catch an unexpected signal.
*/