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sysctl: fold sysctl_writes_strict checks into helper

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The mode sysctl_writes_strict positional checks keep being copy and pasted
as we add new proc handlers.  Just add a helper to avoid code duplication.

Link: http://lkml.kernel.org/r/20170519033554.18592-4-mcgrof@kernel.org
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Suggested-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Luis R. Rodriguez 2017-07-12 14:33:33 -07:00 committed by Linus Torvalds
parent a19ac33749
commit d383d48470
1 changed files with 32 additions and 24 deletions
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56
kernel/sysctl.c
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@ -1970,6 +1970,32 @@ static void warn_sysctl_write(struct ctl_table *table)
current->comm, table->procname);
}
/**
* proc_first_pos_non_zero_ignore - check if firs position is allowed
* @ppos: file position
* @table: the sysctl table
*
* Returns true if the first position is non-zero and the sysctl_writes_strict
* mode indicates this is not allowed for numeric input types. String proc
* hadlers can ignore the return value.
*/
static bool proc_first_pos_non_zero_ignore(loff_t *ppos,
struct ctl_table *table)
{
if (!*ppos)
return false;
switch (sysctl_writes_strict) {
case SYSCTL_WRITES_STRICT:
return true;
case SYSCTL_WRITES_WARN:
warn_sysctl_write(table);
return false;
default:
return false;
}
}
/**
* proc_dostring - read a string sysctl
* @table: the sysctl table
@ -1990,8 +2016,8 @@ static void warn_sysctl_write(struct ctl_table *table)
int proc_dostring(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
if (write && *ppos && sysctl_writes_strict == SYSCTL_WRITES_WARN)
warn_sysctl_write(table);
if (write)
proc_first_pos_non_zero_ignore(ppos, table);
return _proc_do_string((char *)(table->data), table->maxlen, write,
(char __user *)buffer, lenp, ppos);
@ -2193,17 +2219,8 @@ static int __do_proc_dointvec(void *tbl_data, struct ctl_table *table,
conv = do_proc_dointvec_conv;
if (write) {
if (*ppos) {
switch (sysctl_writes_strict) {
case SYSCTL_WRITES_STRICT:
goto out;
case SYSCTL_WRITES_WARN:
warn_sysctl_write(table);
break;
default:
break;
}
}
if (proc_first_pos_non_zero_ignore(ppos, table))
goto out;
if (left > PAGE_SIZE - 1)
left = PAGE_SIZE - 1;
@ -2468,17 +2485,8 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int
left = *lenp;
if (write) {
if (*ppos) {
switch (sysctl_writes_strict) {
case SYSCTL_WRITES_STRICT:
goto out;
case SYSCTL_WRITES_WARN:
warn_sysctl_write(table);
break;
default:
break;
}
}
if (proc_first_pos_non_zero_ignore(ppos, table))
goto out;
if (left > PAGE_SIZE - 1)
left = PAGE_SIZE - 1;