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bsd-user: implement sysctlbyname(2)

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do_freebsd_sysctlbyname needs to translate the 'name' back down to a OID
so we can intercept the special ones. Do that and call the common wrapper
do_freebsd_sysctl_oid.

Signed-off-by: Kyle Evans <kevans@FreeBSD.org>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Signed-off-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Kyle Evans 2023-02-10 11:16:25 -07:00 committed by Warner Losh
parent 7adda6de6d
commit 6da777e212
3 changed files with 74 additions and 0 deletions
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67
bsd-user/freebsd/os-sys.c
View file

@ -471,6 +471,73 @@ out:
return ret;
}
/*
* This syscall was created to make sysctlbyname(3) more efficient, but we can't
* really provide it in bsd-user. Notably, we must always translate the names
* independently since some sysctl values have to be faked for the target
* environment, so it still has to break down to two syscalls for the underlying
* implementation.
*/
abi_long do_freebsd_sysctlbyname(CPUArchState *env, abi_ulong namep,
int32_t namelen, abi_ulong oldp, abi_ulong oldlenp, abi_ulong newp,
abi_ulong newlen)
{
abi_long ret = -TARGET_EFAULT;
void *holdp = NULL, *hnewp = NULL;
char *snamep = NULL;
int oid[CTL_MAXNAME + 2];
size_t holdlen, oidplen;
abi_ulong oldlen = 0;
/* oldlenp is read/write, pre-check here for write */
if (oldlenp) {
if (!access_ok(VERIFY_WRITE, oldlenp, sizeof(abi_ulong)) ||
get_user_ual(oldlen, oldlenp)) {
goto out;
}
}
snamep = lock_user_string(namep);
if (snamep == NULL) {
goto out;
}
if (newp) {
hnewp = lock_user(VERIFY_READ, newp, newlen, 1);
if (hnewp == NULL) {
goto out;
}
}
if (oldp) {
holdp = lock_user(VERIFY_WRITE, oldp, oldlen, 0);
if (holdp == NULL) {
goto out;
}
}
holdlen = oldlen;
oidplen = ARRAY_SIZE(oid);
if (sysctlnametomib(snamep, oid, &oidplen) != 0) {
ret = -TARGET_EINVAL;
goto out;
}
ret = do_freebsd_sysctl_oid(env, oid, oidplen, holdp, &holdlen, hnewp,
newlen);
/*
* writeability pre-checked above. __sysctl(2) returns ENOMEM and updates
* oldlenp for the proper size to use.
*/
if (oldlenp && (ret == 0 || ret == -TARGET_ENOMEM)) {
put_user_ual(holdlen, oldlenp);
}
out:
unlock_user(snamep, namep, 0);
unlock_user(holdp, oldp, ret == 0 ? holdlen : 0);
unlock_user(hnewp, newp, 0);
return ret;
}
abi_long do_freebsd_sysctl(CPUArchState *env, abi_ulong namep, int32_t namelen,
abi_ulong oldp, abi_ulong oldlenp, abi_ulong newp, abi_ulong newlen)
{

4
bsd-user/freebsd/os-syscall.c
View file

@ -498,6 +498,10 @@ static abi_long freebsd_syscall(void *cpu_env, int num, abi_long arg1,
ret = do_freebsd_sysctl(cpu_env, arg1, arg2, arg3, arg4, arg5, arg6);
break;
case TARGET_FREEBSD_NR___sysctlbyname: /* sysctlbyname(2) */
ret = do_freebsd_sysctlbyname(cpu_env, arg1, arg2, arg3, arg4, arg5, arg6);
break;
case TARGET_FREEBSD_NR_sysarch: /* sysarch(2) */
ret = do_freebsd_sysarch(cpu_env, arg1, arg2);
break;

3
bsd-user/qemu.h
View file

@ -255,6 +255,9 @@ int host_to_target_errno(int err);
/* os-sys.c */
abi_long do_freebsd_sysctl(CPUArchState *env, abi_ulong namep, int32_t namelen,
abi_ulong oldp, abi_ulong oldlenp, abi_ulong newp, abi_ulong newlen);
abi_long do_freebsd_sysctlbyname(CPUArchState *env, abi_ulong namep,
int32_t namelen, abi_ulong oldp, abi_ulong oldlenp, abi_ulong newp,
abi_ulong newlen);
abi_long do_freebsd_sysarch(void *cpu_env, abi_long arg1, abi_long arg2);
/* user access */