Messages in this thread Patch in this message | | | From | Maciej Żenczykowski <> | Subject | [PATCH] configfs: make directories inherit uid/gid from creator | Date | Sat, 23 Jan 2021 12:55:16 -0800 |
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From: Maciej Żenczykowski <maze@google.com>
Currently a non-root process can create directories, but cannot create stuff in the directories it creates.
Example (before this patch): phone:/ $ id uid=1000(system) gid=1000(system) groups=1000(system),... context=u:r:su:s0
phone:/ $ cd /config/usb_gadget/g1/configs/
phone:/config/usb_gadget/g1/configs $ ls -lZ drwxr-xr-x 3 system system u:object_r:configfs:s0 0 2020-12-28 06:03 b.1
phone:/config/usb_gadget/g1/configs $ mkdir b.2
phone:/config/usb_gadget/g1/configs $ ls -lZ drwxr-xr-x 3 system system u:object_r:configfs:s0 0 2020-12-28 06:03 b.1 drwxr-xr-x 3 root root u:object_r:configfs:s0 0 2020-12-28 06:51 b.2
phone:/config/usb_gadget/g1/configs $ chown system:system b.2 chown: 'b.2' to 'system:system': Operation not permitted
phone:/config/usb_gadget/g1/configs $ ls -lZ b.1 -rw-r--r-- 1 system system u:object_r:configfs:s0 4096 2020-12-28 05:23 MaxPower -rw-r--r-- 1 system system u:object_r:configfs:s0 4096 2020-12-28 05:23 bmAttributes lrwxrwxrwx 1 root root u:object_r:configfs:s0 0 2020-12-28 05:23 function0 -> ../../../../usb_gadget/g1/functions/ffs.adb drwxr-xr-x 2 system system u:object_r:configfs:s0 0 2020-12-28 05:23 strings
phone:/config/usb_gadget/g1/configs $ ln -s ../../../../usb_gadget/g1/functions/ffs.adb b.2/function0 ln: cannot create symbolic link from '../../../../usb_gadget/g1/functions/ffs.adb' to 'b.2/function0': Permission denied
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Joel Becker <jlbec@evilplan.org> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Maciej Żenczykowski <maze@google.com> Change-Id: Ia907b2def940197b44aa87b337d37c5dde9c5b91 --- fs/configfs/dir.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index b839dd1b459f..04f18402ef7c 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -1410,6 +1410,21 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode else ret = configfs_attach_item(parent_item, item, dentry, frag); + /* inherit uid/gid from process creating the directory */ + if (!uid_eq(current_fsuid(), GLOBAL_ROOT_UID) || + !gid_eq(current_fsgid(), GLOBAL_ROOT_GID)) { + struct inode * inode = d_inode(dentry); + struct iattr ia = { + .ia_uid = current_fsuid(), + .ia_gid = current_fsgid(), + .ia_valid = ATTR_UID | ATTR_GID, + }; + inode->i_uid = ia.ia_uid; + inode->i_gid = ia.ia_gid; + /* (note: the above manual assignments skip the permission checks) */ + (void)configfs_setattr(dentry, &ia); + } + spin_lock(&configfs_dirent_lock); sd->s_type &= ~CONFIGFS_USET_IN_MKDIR; if (!ret) -- 2.30.0.280.ga3ce27912f-goog
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