From: Zheng Liu <wenqing.lz@xxxxxxxxxx>
A new variable is added to enable/disable _NO_HIDE_STALE flag becuase this
flag is possible to be abused.
Signed-off-by: Zheng Liu <wenqing.lz@xxxxxxxxxx>
---
fs/open.c | 10 ++++++++++
include/linux/sysctl.h | 1 +
kernel/sysctl.c | 10 ++++++++++
3 files changed, 21 insertions(+), 0 deletions(-)
diff --git a/fs/open.c b/fs/open.c
index 1d3117f..43fd39c 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -213,6 +213,11 @@ SYSCALL_ALIAS(sys_ftruncate64, SyS_ftruncate64);
#endif
#endif /* BITS_PER_LONG == 32 */
+/*
+ * enable/disable FALLOC_FL_NO_HIDE_STALE flag
+ * 0: disable (default), 1: enable
+ */
+int sysctl_enable_falloc_no_hide_stale = 0;
int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
{
@@ -249,6 +254,11 @@ int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
if (ret)
return ret;
+ /* Check for enabling _NO_HIDE_STALE flag */
+ if (mode & FALLOC_FL_NO_HIDE_STALE &&
+ !sysctl_enable_falloc_no_hide_stale)
+ return -EPERM;
+
if (S_ISFIFO(inode->i_mode))
return -ESPIPE;
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index c34b4c8..484e5dc 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -820,6 +820,7 @@ enum
FS_AIO_NR=18, /* current system-wide number of aio requests */
FS_AIO_MAX_NR=19, /* system-wide maximum number of aio requests */
FS_INOTIFY=20, /* inotify submenu */
+ FS_FALLOC_STALE=21, /* enable fallocate _NO_HIDE_STALE flag */
FS_OCFS2=988, /* ocfs2 */
};
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 4ab1187..37de7c2 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -108,6 +108,7 @@ extern int percpu_pagelist_fraction;
extern int compat_log;
extern int latencytop_enabled;
extern int sysctl_nr_open_min, sysctl_nr_open_max;
+extern int sysctl_enable_falloc_no_hide_stale;
#ifndef CONFIG_MMU
extern int sysctl_nr_trim_pages;
#endif
@@ -1517,6 +1518,15 @@ static struct ctl_table fs_table[] = {
.proc_handler = &pipe_proc_fn,
.extra1 = &pipe_min_size,
},
+ {
+ .procname = "falloc_no_hide_stale",
+ .data = &sysctl_enable_falloc_no_hide_stale,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &one,
+ },
{ }
};
--
1.7.4.1
--
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