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linux/spl: base proc_dohostid() on proc_dostring() 

This fixes /proc/sys/kernel/spl/hostid on kernels with mainline commit
32927393dc1ccd60fb2bdc05b9e8e88753761469 ("sysctl: pass kernel pointers
to ->proc_handler") ‒ 5.7-rc1 and up

The access_ok() check in copy_to_user() in proc_copyout_string() would
always fail, so all userspace reads and writes would fail with EINVAL

proc_dostring() strips only the final new-line,
but simple_strtoul() doesn't actually need a back-trimmed string ‒
writing "012345678   \n" is still allowed, as is "012345678zupsko", &c.

This alters what happens when an invalid value is written ‒
previously it'd get set to what-ever simple_strtoul() returned
(probably 0, thereby resetting it to default), now it does nothing

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #11878
Closes #11879
This commit is contained in:
наб 2021-04-11 01:18:40 +02:00 committed by Brian Behlendorf
parent 4c925936e3
commit e5c4f86e7a
1 changed files with 17 additions and 76 deletions
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93
module/os/linux/spl/spl-proc.c
View File

@ -53,60 +53,6 @@ static struct proc_dir_entry *proc_spl_taskq_all = NULL;
static struct proc_dir_entry *proc_spl_taskq = NULL;
struct proc_dir_entry *proc_spl_kstat = NULL;
static int
proc_copyin_string(char *kbuffer, int kbuffer_size, const char *ubuffer,
int ubuffer_size)
{
int size;
if (ubuffer_size > kbuffer_size)
return (-EOVERFLOW);
if (copy_from_user((void *)kbuffer, (void *)ubuffer, ubuffer_size))
return (-EFAULT);
/* strip trailing whitespace */
size = strnlen(kbuffer, ubuffer_size);
while (size-- >= 0)
if (!isspace(kbuffer[size]))
break;
/* empty string */
if (size < 0)
return (-EINVAL);
/* no space to terminate */
if (size == kbuffer_size)
return (-EOVERFLOW);
kbuffer[size + 1] = 0;
return (0);
}
static int
proc_copyout_string(char *ubuffer, int ubuffer_size, const char *kbuffer,
char *append)
{
/*
* NB if 'append' != NULL, it's a single character to append to the
* copied out string - usually "\n", for /proc entries and
* (i.e. a terminating zero byte) for sysctl entries
*/
int size = MIN(strlen(kbuffer), ubuffer_size);
if (copy_to_user(ubuffer, kbuffer, size))
return (-EFAULT);
if (append != NULL && size < ubuffer_size) {
if (copy_to_user(ubuffer + size, append, 1))
return (-EFAULT);
size++;
}
return (size);
}
#ifdef DEBUG_KMEM
static int
proc_domemused(struct ctl_table *table, int write,
@ -187,39 +133,34 @@ static int
proc_dohostid(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
int len, rc = 0;
char *end, str[32];
unsigned long hid;
spl_ctl_table dummy = *table;
dummy.data = str;
dummy.maxlen = sizeof (str) - 1;
if (!write)
snprintf(str, sizeof (str), "%lx",
(unsigned long) zone_get_hostid(NULL));
/* always returns 0 */
proc_dostring(&dummy, write, buffer, lenp, ppos);
if (write) {
/*
* We can't use proc_doulongvec_minmax() in the write
* case here because hostid while a hex value has no
* leading 0x which confuses the helper function.
* case here because hostid, while a hex value, has no
* leading 0x, which confuses the helper function.
*/
rc = proc_copyin_string(str, sizeof (str), buffer, *lenp);
if (rc < 0)
return (rc);
spl_hostid = simple_strtoul(str, &end, 16);
hid = simple_strtoul(str, &end, 16);
if (str == end)
return (-EINVAL);
} else {
len = snprintf(str, sizeof (str), "%lx",
(unsigned long) zone_get_hostid(NULL));
if (*ppos >= len)
rc = 0;
else
rc = proc_copyout_string(buffer,
*lenp, str + *ppos, "\n");
if (rc >= 0) {
*lenp = rc;
*ppos += rc;
}
spl_hostid = hid;
}
return (rc);
return (0);
}
static void