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Diffstat (limited to 'kernel/sysctl.c')
-rw-r--r--kernel/sysctl.c69
1 files changed, 67 insertions, 2 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index ac6847feaa83..7a910b9081e8 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -173,6 +173,13 @@ extern int no_unaligned_warning;
#endif
#ifdef CONFIG_PROC_SYSCTL
+
+#define SYSCTL_WRITES_LEGACY -1
+#define SYSCTL_WRITES_WARN 0
+#define SYSCTL_WRITES_STRICT 1
+
+static int sysctl_writes_strict = SYSCTL_WRITES_WARN;
+
static int proc_do_cad_pid(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos);
static int proc_taint(struct ctl_table *table, int write,
@@ -495,6 +502,15 @@ static struct ctl_table kern_table[] = {
.mode = 0644,
.proc_handler = proc_taint,
},
+ {
+ .procname = "sysctl_writes_strict",
+ .data = &sysctl_writes_strict,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &neg_one,
+ .extra2 = &one,
+ },
#endif
#ifdef CONFIG_LATENCYTOP
{
@@ -1717,8 +1733,20 @@ static int _proc_do_string(char *data, int maxlen, int write,
}
if (write) {
- /* Start writing from beginning of buffer. */
- len = 0;
+ if (sysctl_writes_strict == SYSCTL_WRITES_STRICT) {
+ /* Only continue writes not past the end of buffer. */
+ len = strlen(data);
+ if (len > maxlen - 1)
+ len = maxlen - 1;
+
+ if (*ppos > len)
+ return 0;
+ len = *ppos;
+ } else {
+ /* Start writing from beginning of buffer. */
+ len = 0;
+ }
+
*ppos += *lenp;
p = buffer;
while ((p - buffer) < *lenp && len < maxlen - 1) {
@@ -1758,6 +1786,14 @@ static int _proc_do_string(char *data, int maxlen, int write,
return 0;
}
+static void warn_sysctl_write(struct ctl_table *table)
+{
+ pr_warn_once("%s wrote to %s when file position was not 0!\n"
+ "This will not be supported in the future. To silence this\n"
+ "warning, set kernel.sysctl_writes_strict = -1\n",
+ current->comm, table->procname);
+}
+
/**
* proc_dostring - read a string sysctl
* @table: the sysctl table
@@ -1778,6 +1814,9 @@ static int _proc_do_string(char *data, int maxlen, int write,
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);
+
return _proc_do_string((char *)(table->data), table->maxlen, write,
(char __user *)buffer, lenp, ppos);
}
@@ -1953,6 +1992,18 @@ 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 (left > PAGE_SIZE - 1)
left = PAGE_SIZE - 1;
page = __get_free_page(GFP_TEMPORARY);
@@ -2010,6 +2061,7 @@ free:
return err ? : -EINVAL;
}
*lenp -= left;
+out:
*ppos += *lenp;
return err;
}
@@ -2202,6 +2254,18 @@ 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 (left > PAGE_SIZE - 1)
left = PAGE_SIZE - 1;
page = __get_free_page(GFP_TEMPORARY);
@@ -2257,6 +2321,7 @@ free:
return err ? : -EINVAL;
}
*lenp -= left;
+out:
*ppos += *lenp;
return err;
}