d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Make sysctl user.local a tunable that can be written at run-time

Browse Source 
This sysctl value had been provided as a read-only variable that is
compiled into the C library based on the value of _PATH_LOCALBASE in
paths.h.

After this change, the value is compiled into the kernel as an empty
string, which is translated to _PATH_LOCALBASE by the C library.

This empty string can be overridden at boot time or by a privileged
user at run time and will then be returned by sysctl.

When set to an empty string, the value returned by sysctl reverts to
_PATH_LOCALBASE.

This update does not change the behavior on any system that does
not modify the default value of user.localbase.

I consider this change as experimental and would prefer if the run-time
write permission was reconsidered and the sysctl variable defined with
CLFLAG_RDTUN instead to restrict it to be set at boot time.

MFC after:	1 month
This commit is contained in:
se 2020-10-31 23:48:41 +00:00
parent 1d346b5b45
commit 8faaaf3325
2 changed files with 23 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
lib/libc/gen/sysctl.c
View File

@ -68,14 +68,14 @@ sysctl(const int *name, u_int namelen, void *oldp, size_t *oldlenp,
if (retval || name[0] != CTL_USER)
return (retval);
if (newp != NULL) {
errno = EPERM;
return (-1);
}
if (namelen != 2) {
errno = EINVAL;
return (-1);
}
if (newp != NULL && name[1] != USER_LOCALBASE) {
errno = EPERM;
return (-1);
}
switch (name[1]) {
case USER_CS_PATH:
@ -88,13 +88,21 @@ sysctl(const int *name, u_int namelen, void *oldp, size_t *oldlenp,
memmove(oldp, _PATH_STDPATH, sizeof(_PATH_STDPATH));
return (0);
case USER_LOCALBASE:
if (oldp != NULL && orig_oldlen < sizeof(_PATH_LOCALBASE)) {
errno = ENOMEM;
return (-1);
if (oldlenp != NULL) {
if (oldp == NULL) {
if (*oldlenp == 1)
*oldlenp = sizeof(_PATH_LOCALBASE);
} else {
if (*oldlenp != 1)
return (retval);
if (orig_oldlen < sizeof(_PATH_LOCALBASE)) {
errno = ENOMEM;
return (-1);
}
*oldlenp = sizeof(_PATH_LOCALBASE);
memmove(oldp, _PATH_LOCALBASE, sizeof(_PATH_LOCALBASE));
}
}
*oldlenp = sizeof(_PATH_LOCALBASE);
if (oldp != NULL)
memmove(oldp, _PATH_LOCALBASE, sizeof(_PATH_LOCALBASE));
return (0);
}

7
sys/kern/kern_mib.c
View File

@ -652,8 +652,11 @@ SYSCTL_INT(_user, USER_STREAM_MAX, stream_max, CTLFLAG_RD,
SYSCTL_NULL_INT_PTR, 0, "Min Maximum number of streams a process may have open at one time");
SYSCTL_INT(_user, USER_TZNAME_MAX, tzname_max, CTLFLAG_RD,
SYSCTL_NULL_INT_PTR, 0, "Min Maximum number of types supported for timezone names");
SYSCTL_STRING(_user, USER_LOCALBASE, localbase, CTLFLAG_RD,
"", 0, "Prefix used to install and locate add-on packages");
static char localbase[MAXPATHLEN] = "";
SYSCTL_STRING(_user, USER_LOCALBASE, localbase, CTLFLAG_RWTUN,
localbase, sizeof(localbase), "Prefix used to install and locate add-on packages");
#include <sys/vnode.h>
SYSCTL_INT(_debug_sizeof, OID_AUTO, vnode, CTLFLAG_RD,