From: Andreas Gruenbacher <agruen@xxxxxxxxxx> Normally, deleting a file requires write access to the parent directory. Some permission models use a different permission on the parent directory to indicate delete access. In addition, a process can have per-file delete access even without delete access on the parent directory. Introduce two new inode_permission() mask flags and use them in may_delete() Acked-by: David Howells <dhowells@xxxxxxxxxx> Signed-off-by: Andreas Gruenbacher <agruen@xxxxxxxxxx> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> --- fs/namei.c | 42 ++++++++++++++++++++++++++++-------------- include/linux/fs.h | 2 ++ 2 files changed, 30 insertions(+), 14 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index f6184b8..7bf42e8 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -337,7 +337,7 @@ static inline int do_inode_permission(struct inode *inode, int mask) * are used for other things. * * When checking for MAY_APPEND, MAY_CREATE_FILE, MAY_CREATE_DIR, - * MAY_WRITE must also be set in @mask. + * MAY_DELETE_CHILD, MAY_DELETE_SELF, MAY_WRITE must also be set in @mask. */ int inode_permission(struct inode *inode, int mask) { @@ -1853,7 +1853,7 @@ static inline int check_sticky(struct inode *dir, struct inode *inode) return 0; other_userns: - return !ns_capable(inode_userns(inode), CAP_FOWNER); + return 1; } /* @@ -1875,30 +1875,44 @@ other_userns: * 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,int isdir) +static int may_delete(struct inode *dir, struct dentry *victim, + int isdir, int replace) { - int error; + struct inode *inode = victim->d_inode; + int mask, replace_mask = 0, error, is_sticky; + - if (!victim->d_inode) + if (!inode) return -ENOENT; BUG_ON(victim->d_parent->d_inode != dir); audit_inode_child(victim, dir); - error = inode_permission(dir, MAY_WRITE | MAY_EXEC); + mask = MAY_WRITE | MAY_EXEC | MAY_DELETE_CHILD; + if (replace) + replace_mask = S_ISDIR(inode->i_mode) ? + MAY_CREATE_DIR : MAY_CREATE_FILE; + is_sticky = check_sticky(dir, inode); + error = inode_permission(dir, mask | replace_mask); + if ((error || is_sticky) && IS_RICHACL(inode) && + (inode_permission(dir, MAY_EXEC | replace_mask) == 0) && + (inode_permission(inode, MAY_DELETE_SELF) == 0)) + error = 0; + else if (!error && is_sticky && + !ns_capable(inode_userns(inode), CAP_FOWNER)) + error = -EPERM; if (error) return error; if (IS_APPEND(dir)) return -EPERM; - if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| - IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) + if (IS_APPEND(inode) || IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) return -EPERM; if (isdir) { - if (!S_ISDIR(victim->d_inode->i_mode)) + if (!S_ISDIR(inode->i_mode)) return -ENOTDIR; if (IS_ROOT(victim)) return -EBUSY; - } else if (S_ISDIR(victim->d_inode->i_mode)) + } else if (S_ISDIR(inode->i_mode)) return -EISDIR; if (IS_DEADDIR(dir)) return -ENOENT; @@ -2605,7 +2619,7 @@ void dentry_unhash(struct dentry *dentry) int vfs_rmdir(struct inode *dir, struct dentry *dentry) { - int error = may_delete(dir, dentry, 1); + int error = may_delete(dir, dentry, 1, 0); if (error) return error; @@ -2700,7 +2714,7 @@ SYSCALL_DEFINE1(rmdir, const char __user *, pathname) int vfs_unlink(struct inode *dir, struct dentry *dentry) { - int error = may_delete(dir, dentry, 0); + int error = may_delete(dir, dentry, 0, 0); if (error) return error; @@ -3096,14 +3110,14 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, if (old_dentry->d_inode == new_dentry->d_inode) return 0; - error = may_delete(old_dir, old_dentry, is_dir); + error = may_delete(old_dir, old_dentry, is_dir, 0); if (error) return error; if (!new_dentry->d_inode) error = may_create(new_dir, new_dentry, is_dir); else - error = may_delete(new_dir, new_dentry, is_dir); + error = may_delete(new_dir, new_dentry, is_dir, 1); if (error) return error; diff --git a/include/linux/fs.h b/include/linux/fs.h index 60361c6..ccece40 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -69,6 +69,8 @@ struct inodes_stat_t { #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 -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html