From: Miklos Szeredi <mszeredi@redhat.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Subject: [PATCH 08/12] vfs: allow unprivileged whiteout creation
Date: Thu, 28 Nov 2019 16:59:36 +0100 [thread overview]
Message-ID: <20191128155940.17530-9-mszeredi@redhat.com> (raw)
In-Reply-To: <20191128155940.17530-1-mszeredi@redhat.com>
Whiteouts are special, but unlike real device nodes they should not require
privileges to create.
The 0 char device number should already be reserved, but make this explicit
in cdev_add() to be on the safe side.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
fs/char_dev.c | 3 +++
fs/namei.c | 17 ++++-------------
include/linux/device_cgroup.h | 3 +++
3 files changed, 10 insertions(+), 13 deletions(-)
diff --git a/fs/char_dev.c b/fs/char_dev.c
index 00dfe17871ac..8bf66f40e5e0 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -483,6 +483,9 @@ int cdev_add(struct cdev *p, dev_t dev, unsigned count)
p->dev = dev;
p->count = count;
+ if (WARN_ON(dev == WHITEOUT_DEV))
+ return -EBUSY;
+
error = kobj_map(cdev_map, dev, count, NULL,
exact_match, exact_lock, p);
if (error)
diff --git a/fs/namei.c b/fs/namei.c
index 671c3c1a3425..05ca98595b62 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3687,12 +3687,14 @@ EXPORT_SYMBOL(user_path_create);
int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
{
+ bool is_whiteout = S_ISCHR(mode) && dev == WHITEOUT_DEV;
int error = may_create(dir, dentry);
if (error)
return error;
- if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
+ if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD) &&
+ !is_whiteout)
return -EPERM;
if (!dir->i_op->mknod)
@@ -4527,9 +4529,6 @@ static int do_renameat2(int olddfd, const char __user *oldname, int newdfd,
(flags & RENAME_EXCHANGE))
return -EINVAL;
- if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD))
- return -EPERM;
-
if (flags & RENAME_EXCHANGE)
target_flags = 0;
@@ -4667,15 +4666,7 @@ SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newna
int vfs_whiteout(struct inode *dir, struct dentry *dentry)
{
- int error = may_create(dir, dentry);
- if (error)
- return error;
-
- if (!dir->i_op->mknod)
- return -EPERM;
-
- return dir->i_op->mknod(dir, dentry,
- S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
+ return vfs_mknod(dir, dentry, S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
}
EXPORT_SYMBOL(vfs_whiteout);
diff --git a/include/linux/device_cgroup.h b/include/linux/device_cgroup.h
index 8557efe096dc..fc989487c273 100644
--- a/include/linux/device_cgroup.h
+++ b/include/linux/device_cgroup.h
@@ -62,6 +62,9 @@ static inline int devcgroup_inode_mknod(int mode, dev_t dev)
if (!S_ISBLK(mode) && !S_ISCHR(mode))
return 0;
+ if (S_ISCHR(mode) && dev == WHITEOUT_DEV)
+ return 0;
+
if (S_ISBLK(mode))
type = DEVCG_DEV_BLOCK;
else
--
2.21.0
next prev parent reply other threads:[~2019-11-28 16:00 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-28 15:59 [PATCH 00/12] various vfs patches Miklos Szeredi
2019-11-28 15:59 ` [PATCH 01/12] aio: fix async fsync creds Miklos Szeredi
2019-12-13 9:32 ` Miklos Szeredi
2020-05-04 8:05 ` Avi Kivity
2019-11-28 15:59 ` [PATCH 02/12] fs_parse: fix fs_param_v_optional handling Miklos Szeredi
2019-11-29 11:31 ` Andrew Price
2019-11-29 14:43 ` Miklos Szeredi
2019-11-29 15:56 ` Andrew Price
2019-12-16 23:28 ` Al Viro
2019-12-17 1:18 ` Al Viro
2019-12-17 3:27 ` Al Viro
2019-11-28 15:59 ` [PATCH 03/12] vfs: verify param type in vfs_parse_sb_flag() Miklos Szeredi
2019-11-28 15:59 ` [PATCH 04/12] uapi: deprecate STATX_ALL Miklos Szeredi
2019-11-28 15:59 ` [PATCH 05/12] statx: don't clear STATX_ATIME on SB_RDONLY Miklos Szeredi
2019-11-28 15:59 ` [PATCH 06/12] utimensat: AT_EMPTY_PATH support Miklos Szeredi
2019-11-28 15:59 ` [PATCH 07/12] f*xattr: allow O_PATH descriptors Miklos Szeredi
2019-11-28 15:59 ` Miklos Szeredi [this message]
2019-12-17 3:51 ` [PATCH 08/12] vfs: allow unprivileged whiteout creation Al Viro
2019-12-17 4:22 ` Miklos Szeredi
2019-11-28 15:59 ` [PATCH 09/12] fs_parser: "string" with missing value is a "flag" Miklos Szeredi
2019-12-17 17:32 ` Al Viro
2019-12-17 18:31 ` Al Viro
2019-11-28 15:59 ` [PATCH 10/12] vfs: don't parse forbidden flags Miklos Szeredi
2019-11-28 15:59 ` [PATCH 11/12] vfs: don't parse "posixacl" option Miklos Szeredi
2019-12-17 3:42 ` Al Viro
2019-12-17 4:18 ` Miklos Szeredi
2019-12-17 4:28 ` Al Viro
2019-11-28 15:59 ` [PATCH 12/12] vfs: don't parse "silent" option Miklos Szeredi
2019-12-17 3:37 ` Al Viro
2019-12-17 4:12 ` Miklos Szeredi
2019-12-17 4:16 ` Miklos Szeredi
2019-12-17 4:19 ` Al Viro
2019-12-17 4:23 ` Miklos Szeredi
2019-12-17 4:28 ` Miklos Szeredi
2019-12-17 4:17 ` Al Viro
2019-12-13 9:33 ` [PATCH 00/12] various vfs patches Miklos Szeredi
2019-12-16 23:13 ` Al Viro
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