On Thu, 2016-06-30 at 15:46 +0200, Andreas Gruenbacher wrote: > Richacls distinguish between creating non-directories and directories. To > support that, add an isdir parameter to may_create(). When checking > inode_permission() for create permission, pass in an additional > MAY_CREATE_FILE or MAY_CREATE_DIR mask flag. > > Add may_replace() to allow checking for delete and create access when > replacing an existing file in vfs_rename(). > > Signed-off-by: Andreas Gruenbacher <[email protected]> > Reviewed-by: J. Bruce Fields <[email protected]> > Reviewed-by: Andreas Dilger <[email protected]> > Reviewed-by: Steve French <[email protected]> > --- > fs/namei.c | 49 +++++++++++++++++++++++++++++++++---------------- > include/linux/fs.h | 2 ++ > 2 files changed, 35 insertions(+), 16 deletions(-) > > diff --git a/fs/namei.c b/fs/namei.c > index 7cc5487..dc91858 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -454,7 +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. > * > - * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. > + * 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. > */ > int inode_permission(struct inode *inode, int mask) > { > @@ -2763,7 +2765,8 @@ EXPORT_SYMBOL(__check_sticky); > * 10. We don't allow removal of NFS sillyrenamed files; it's handled by > * nfs_async_unlink(). > */ > -static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) > +static int may_delete_or_replace(struct inode *dir, struct dentry *victim, > + bool isdir, int mask) > { > struct inode *inode = d_backing_inode(victim); > int error; > @@ -2775,7 +2778,7 @@ static int may_delete(struct inode *dir, struct dentry > *victim, bool isdir) > BUG_ON(victim->d_parent->d_inode != dir); > audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); > > - error = inode_permission(dir, MAY_WRITE | MAY_EXEC); > + error = inode_permission(dir, mask); > if (error) > return error; > if (IS_APPEND(dir)) > @@ -2798,6 +2801,18 @@ static int may_delete(struct inode *dir, struct dentry > *victim, bool isdir) > return 0; > } > > +static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) > +{ > + return may_delete_or_replace(dir, victim, isdir, MAY_WRITE | MAY_EXEC); > +} > + > +static int may_replace(struct inode *dir, struct dentry *victim, bool isdir) > +{ > + int mask = isdir ? MAY_CREATE_DIR : MAY_CREATE_FILE; > + > + return may_delete_or_replace(dir, victim, isdir, mask | MAY_WRITE | > MAY_EXEC); > +} > + > /* Check whether we can create an object with dentry child in directory > * dir. > * 1. We can't do it if child already exists (open has special treatment for > @@ -2806,14 +2821,16 @@ static int may_delete(struct inode *dir, struct > dentry *victim, bool isdir) > * 3. We should have write and exec permissions on dir > * 4. We can't do it if dir is immutable (done in permission()) > */ > -static inline int may_create(struct inode *dir, struct dentry *child) > +static inline int may_create(struct inode *dir, struct dentry *child, bool > isdir) > { > + int mask = isdir ? MAY_CREATE_DIR : MAY_CREATE_FILE; > + > audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); > if (child->d_inode) > return -EEXIST; > if (IS_DEADDIR(dir)) > return -ENOENT; > - return inode_permission(dir, MAY_WRITE | MAY_EXEC); > + return inode_permission(dir, MAY_WRITE | MAY_EXEC | mask); > } > > /* > @@ -2863,7 +2880,7 @@ EXPORT_SYMBOL(unlock_rename); > int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, > bool want_excl) > { > - int error = may_create(dir, dentry); > + int error = may_create(dir, dentry, false); > if (error) > return error; > > @@ -3650,7 +3667,7 @@ EXPORT_SYMBOL(user_path_create); > > int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t > dev) > { > - int error = may_create(dir, dentry); > + int error = may_create(dir, dentry, false); > > if (error) > return error; > @@ -3744,7 +3761,7 @@ SYSCALL_DEFINE3(mknod, const char __user *, filename, > umode_t, mode, unsigned, d > > int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) > { > - int error = may_create(dir, dentry); > + int error = may_create(dir, dentry, true); > unsigned max_links = dir->i_sb->s_max_links; > > if (error) > @@ -3800,7 +3817,7 @@ SYSCALL_DEFINE2(mkdir, const char __user *, pathname, > umode_t, mode) > > int vfs_rmdir(struct inode *dir, struct dentry *dentry) > { > - int error = may_delete(dir, dentry, 1); > + int error = may_delete(dir, dentry, true); > > if (error) > return error; > @@ -3922,7 +3939,7 @@ SYSCALL_DEFINE1(rmdir, const char __user *, pathname) > int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode > **delegated_inode) > { > struct inode *target = dentry->d_inode; > - int error = may_delete(dir, dentry, 0); > + int error = may_delete(dir, dentry, false); > > if (error) > return error; > @@ -4056,7 +4073,7 @@ SYSCALL_DEFINE1(unlink, const char __user *, pathname) > > int vfs_symlink(struct inode *dir, struct dentry *dentry, const char > *oldname) > { > - int error = may_create(dir, dentry); > + int error = may_create(dir, dentry, false); > > if (error) > return error; > @@ -4139,7 +4156,7 @@ int vfs_link(struct dentry *old_dentry, struct inode > *dir, struct dentry *new_de > if (!inode) > return -ENOENT; > > - error = may_create(dir, new_dentry); > + error = may_create(dir, new_dentry, false); > if (error) > return error; > > @@ -4336,14 +4353,14 @@ int vfs_rename(struct inode *old_dir, struct dentry > *old_dentry, > return error; > > if (!target) { > - error = may_create(new_dir, new_dentry); > + error = may_create(new_dir, new_dentry, is_dir); > } else { > new_is_dir = d_is_dir(new_dentry); > > if (!(flags & RENAME_EXCHANGE)) > - error = may_delete(new_dir, new_dentry, is_dir); > + error = may_replace(new_dir, new_dentry, is_dir); > else > - error = may_delete(new_dir, new_dentry, new_is_dir); > + error = may_replace(new_dir, new_dentry, new_is_dir); > } > if (error) > return error; > @@ -4606,7 +4623,7 @@ 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); > + int error = may_create(dir, dentry, false); > if (error) > return error; > > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 4ad130c..dd614ad 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -84,6 +84,8 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t > offset, > #define MAY_CHDIR 0x00000040 > /* called from RCU mode, don't block */ > #define MAY_NOT_BLOCK 0x00000080 > +#define MAY_CREATE_FILE 0x00000100 > +#define MAY_CREATE_DIR 0x00000200 > > /* > * flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must > correspond
Reviewed-by: Jeff Layton <[email protected]>
