diff options
| author | Miklos Szeredi <mszeredi@redhat.com> | 2016-09-16 12:44:20 +0200 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2016-09-16 12:44:20 +0200 |
| commit | f2b20f6ee842313a0d681dbbf7f87b70291a6a3b (patch) | |
| tree | b4bea4c83e1968a4f69592e9a7fc15be81750a8c | |
| parent | e71b9dff0634edb127f449e076e883ef24a8c76c (diff) | |
| download | linux-f2b20f6ee842313a0d681dbbf7f87b70291a6a3b.tar.bz2 | |
vfs: move permission checking into notify_change() for utimes(NULL)
This fixes a bug where the permission was not properly checked in
overlayfs. The testcase is ltp/utimensat01.
It is also cleaner and safer to do the permission checking in the vfs
helper instead of the caller.
This patch introduces an additional ia_valid flag ATTR_TOUCH (since
touch(1) is the most obvious user of utimes(NULL)) that is passed into
notify_change whenever the conditions for this special permission checking
mode are met.
Reported-by: Aihua Zhang <zhangaihua1@huawei.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Tested-by: Aihua Zhang <zhangaihua1@huawei.com>
Cc: <stable@vger.kernel.org> # v3.18+
| -rw-r--r-- | fs/attr.c | 15 | ||||
| -rw-r--r-- | fs/utimes.c | 17 | ||||
| -rw-r--r-- | include/linux/fs.h | 1 |
3 files changed, 17 insertions, 16 deletions
diff --git a/fs/attr.c b/fs/attr.c index 42bb42bb3c72..3c42cab06b5d 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -202,6 +202,21 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de return -EPERM; } + /* + * If utimes(2) and friends are called with times == NULL (or both + * times are UTIME_NOW), then we need to check for write permission + */ + if (ia_valid & ATTR_TOUCH) { + if (IS_IMMUTABLE(inode)) + return -EPERM; + + if (!inode_owner_or_capable(inode)) { + error = inode_permission(inode, MAY_WRITE); + if (error) + return error; + } + } + if ((ia_valid & ATTR_MODE)) { umode_t amode = attr->ia_mode; /* Flag setting protected by i_mutex */ diff --git a/fs/utimes.c b/fs/utimes.c index 794f5f5b1fb5..ba54b9e648c9 100644 --- a/fs/utimes.c +++ b/fs/utimes.c @@ -87,21 +87,7 @@ static int utimes_common(struct path *path, struct timespec *times) */ newattrs.ia_valid |= ATTR_TIMES_SET; } else { - /* - * If times is NULL (or both times are UTIME_NOW), - * then we need to check permissions, because - * inode_change_ok() won't do it. - */ - error = -EPERM; - if (IS_IMMUTABLE(inode)) - goto mnt_drop_write_and_out; - - error = -EACCES; - if (!inode_owner_or_capable(inode)) { - error = inode_permission(inode, MAY_WRITE); - if (error) - goto mnt_drop_write_and_out; - } + newattrs.ia_valid |= ATTR_TOUCH; } retry_deleg: inode_lock(inode); @@ -113,7 +99,6 @@ retry_deleg: goto retry_deleg; } -mnt_drop_write_and_out: mnt_drop_write(path->mnt); out: return error; diff --git a/include/linux/fs.h b/include/linux/fs.h index 901e25d495cc..7c391366fb43 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -224,6 +224,7 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset, #define ATTR_KILL_PRIV (1 << 14) #define ATTR_OPEN (1 << 15) /* Truncating from open(O_TRUNC) */ #define ATTR_TIMES_SET (1 << 16) +#define ATTR_TOUCH (1 << 17) /* * Whiteout is represented by a char device. The following constants define the |