On Thu, 2016-06-30 at 15:46 +0200, Andreas Gruenbacher wrote: > Normally, deleting a file requires MAY_WRITE access to the parent > directory. With richacls, a file may be deleted with MAY_DELETE_CHILD access > to the parent directory or with MAY_DELETE_SELF access to the file. > > To support that, pass the MAY_DELETE_CHILD mask flag to inode_permission() > when checking for delete access inside a directory, and MAY_DELETE_SELF > when checking for delete access to a file itelf. >
Minor misspelling in changelog above. It should be "itself". > The MAY_DELETE_SELF permission overrides the sticky directory check. > > Signed-off-by: Andreas Gruenbacher <[email protected]> > Reviewed-by: J. Bruce Fields <[email protected]> > Reviewed-by: Steve French <[email protected]> > --- > fs/namei.c | 20 ++++++++++++-------- > include/linux/fs.h | 2 ++ > 2 files changed, 14 insertions(+), 8 deletions(-) > > diff --git a/fs/namei.c b/fs/namei.c > index dc91858..663933e 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -454,9 +454,9 @@ static int sb_permission(struct super_block *sb, struct > inode *inode, int mask) > * this, letting us set arbitrary permissions for filesystem access without > * changing the "normal" UIDs which are used for other things. > * > - * MAY_WRITE must be set in @mask whenever MAY_APPEND, MAY_CREATE_FILE, or > - * MAY_CREATE_DIR are set. That way, file systems that don't support these > - * permissions will check for MAY_WRITE instead. > + * MAY_WRITE must be set in @mask whenever MAY_APPEND, MAY_CREATE_FILE, > + * MAY_CREATE_DIR, or MAY_DELETE_CHILD are set. That way, file systems that > + * don't support these permissions will check for MAY_WRITE instead. > */ > int inode_permission(struct inode *inode, int mask) > { > @@ -2778,14 +2778,18 @@ static int may_delete_or_replace(struct inode *dir, > struct dentry *victim, > BUG_ON(victim->d_parent->d_inode != dir); > audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); > > - error = inode_permission(dir, mask); > + error = inode_permission(dir, mask | MAY_WRITE | MAY_DELETE_CHILD); > + if (!error && check_sticky(dir, inode)) > + error = -EPERM; > + if (error && IS_RICHACL(inode) && > + inode_permission(inode, MAY_DELETE_SELF) == 0 && > + inode_permission(dir, mask) == 0) > + error = 0; > if (error) > return error; > if (IS_APPEND(dir)) > return -EPERM; > - > - if (check_sticky(dir, inode) || IS_APPEND(inode) || > - IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) > + if (IS_APPEND(inode) || IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) > return -EPERM; > if (isdir) { > if (!d_is_dir(victim)) > @@ -2803,7 +2807,7 @@ static int may_delete_or_replace(struct inode *dir, > struct dentry *victim, > > static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) > { > - return may_delete_or_replace(dir, victim, isdir, MAY_WRITE | MAY_EXEC); > + return may_delete_or_replace(dir, victim, isdir, MAY_EXEC); > } > > static int may_replace(struct inode *dir, struct dentry *victim, bool isdir) > diff --git a/include/linux/fs.h b/include/linux/fs.h > index dd614ad..86bfa10 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -86,6 +86,8 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t > offset, > #define MAY_NOT_BLOCK 0x00000080 > #define MAY_CREATE_FILE 0x00000100 > #define MAY_CREATE_DIR 0x00000200 > +#define MAY_DELETE_CHILD 0x00000400 > +#define MAY_DELETE_SELF 0x00000800 > > /* > * flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must > correspond Reviewed-by: Jeff Layton <[email protected]>
