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Code Issues Releases Activity

Use time_t for intermediate values to avoid overflow in clock_ts_to_ct

Browse Source 
Add additionally safety and overflow checks to clock_ts_to_ct and the
BCD routines while we're here.

Perform a safety check in sys_clock_settime() first to avoid easy local
root panic, without having to propagate an error value back through
dozens of APIs currently lacking error returns.

PR:		211960, 214300
Submitted by:	Justin McOmie <justin.mcomie at gmail.com>, kib@
Reported by:	Tim Newsham <tim.newsham at nccgroup.trust>
Reviewed by:	kib@
Sponsored by:	Dell EMC Isilon, FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D9279
This commit is contained in:
Conrad Meyer 2017-01-24 18:05:29 +00:00
parent 86e01d5add
commit 90a79ac576
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=312702
4 changed files with 56 additions and 4 deletions
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7
sys/kern/kern_time.c
View File

@ -387,6 +387,11 @@ sys_clock_settime(struct thread *td, struct clock_settime_args *uap)
return (kern_clock_settime(td, uap->clock_id, &ats));
}
static int allow_insane_settime = 0;
SYSCTL_INT(_debug, OID_AUTO, allow_insane_settime, CTLFLAG_RWTUN,
&allow_insane_settime, 0,
"do not perform possibly restrictive checks on settime(2) args");
int
kern_clock_settime(struct thread *td, clockid_t clock_id, struct timespec *ats)
{
@ -400,6 +405,8 @@ kern_clock_settime(struct thread *td, clockid_t clock_id, struct timespec *ats)
if (ats->tv_nsec < 0 || ats->tv_nsec >= 1000000000 ||
ats->tv_sec < 0)
return (EINVAL);
if (!allow_insane_settime && ats->tv_sec > 9999ULL * 366 * 24 * 60 * 60)
return (EINVAL);
/* XXX Don't convert nsec->usec and back */
TIMESPEC_TO_TIMEVAL(&atv, ats);
error = settime(td, &atv);

16
sys/kern/subr_clock.c
View File

@ -178,7 +178,7 @@ clock_ct_to_ts(struct clocktime *ct, struct timespec *ts)
void
clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
{
int i, year, days;
time_t i, year, days;
time_t rsec; /* remainder seconds */
time_t secs;
@ -214,6 +214,20 @@ clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
print_ct(ct);
printf("\n");
}
KASSERT(ct->year >= 0 && ct->year < 10000,
("year %d isn't a 4 digit year", ct->year));
KASSERT(ct->mon >= 1 && ct->mon <= 12,
("month %d not in 1-12", ct->mon));
KASSERT(ct->day >= 1 && ct->day <= 31,
("day %d not in 1-31", ct->day));
KASSERT(ct->hour >= 0 && ct->hour <= 23,
("hour %d not in 0-23", ct->hour));
KASSERT(ct->min >= 0 && ct->min <= 59,
("minute %d not in 0-59", ct->min));
/* Not sure if this interface needs to handle leapseconds or not. */
KASSERT(ct->sec >= 0 && ct->sec <= 60,
("seconds %d not in 0-60", ct->sec));
}
int

4
sys/libkern/bcd.c
View File

@ -6,6 +6,7 @@
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/libkern.h>
u_char const bcd2bin_data[] = {
@ -20,6 +21,7 @@ u_char const bcd2bin_data[] = {
80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 0, 0, 0, 0, 0, 0,
90, 91, 92, 93, 94, 95, 96, 97, 98, 99
};
CTASSERT(nitems(bcd2bin_data) == LIBKERN_LEN_BCD2BIN);
u_char const bin2bcd_data[] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
@ -33,6 +35,8 @@ u_char const bin2bcd_data[] = {
0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99
};
CTASSERT(nitems(bin2bcd_data) == LIBKERN_LEN_BIN2BCD);
/* This is actually used with radix [2..36] */
char const hex2ascii_data[] = "0123456789abcdefghijklmnopqrstuvwxyz";
CTASSERT(nitems(hex2ascii_data) == LIBKERN_LEN_HEX2ASCII + 1);

33
sys/sys/libkern.h
View File

@ -49,9 +49,36 @@ extern u_char const bcd2bin_data[];
extern u_char const bin2bcd_data[];
extern char const hex2ascii_data[];
#define bcd2bin(bcd) (bcd2bin_data[bcd])
#define bin2bcd(bin) (bin2bcd_data[bin])
#define hex2ascii(hex) (hex2ascii_data[hex])
#define LIBKERN_LEN_BCD2BIN 154
#define LIBKERN_LEN_BIN2BCD 100
#define LIBKERN_LEN_HEX2ASCII 36
static inline u_char
bcd2bin(int bcd)
{
KASSERT(bcd >= 0 && bcd < LIBKERN_LEN_BCD2BIN,
("invalid bcd %d", bcd));
return (bcd2bin_data[bcd]);
}
static inline u_char
bin2bcd(int bin)
{
KASSERT(bin >= 0 && bin < LIBKERN_LEN_BIN2BCD,
("invalid bin %d", bin));
return (bin2bcd_data[bin]);
}
static inline char
hex2ascii(int hex)
{
KASSERT(hex >= 0 && hex < LIBKERN_LEN_HEX2ASCII,
("invalid hex %d", hex));
return (hex2ascii_data[hex]);
}
static __inline int imax(int a, int b) { return (a > b ? a : b); }
static __inline int imin(int a, int b) { return (a < b ? a : b); }