[PATCH v5 03/39] vfs: Add MAY_DELETE_SELF and MAY_DELETE_CHILD permission flags
From: Andreas Gruenbacher <hidden>
Date: 2015-07-22 13:04:07
Also in:
linux-fsdevel, linux-nfs, lkml
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
From: Andreas Gruenbacher <agruenba@redhat.com> Normally, deleting a file requires write and execute access to the parent directory. With Richacls, a process with MAY_DELETE_SELF access to a file may delete the file even without write access to the parent directory. 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. The MAY_DELETE_SELF permission does not override the sticky directory check. It probably should. Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com> --- fs/namei.c | 15 +++++++++++---- include/linux/fs.h | 2 ++ 2 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 1e2b1fa..86be72c 100644
--- a/fs/namei.c
+++ b/fs/namei.c@@ -454,7 +454,7 @@ static int sb_permission(struct super_block *sb, struct inode *inode, int mask) * changing the "normal" UIDs which 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) {
@@ -2522,7 +2522,7 @@ static int may_delete(struct inode *dir, struct dentry *victim, bool isdir, bool replace) { struct inode *inode = d_backing_inode(victim); - int error, mask = MAY_WRITE | MAY_EXEC; + int error, mask = MAY_EXEC; if (d_is_negative(victim)) return -ENOENT;
@@ -2532,8 +2532,15 @@ static int may_delete(struct inode *dir, struct dentry *victim, audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); if (replace) - mask |= isdir ? MAY_CREATE_DIR : MAY_CREATE_FILE; - error = inode_permission(dir, mask); + mask |= MAY_WRITE | (isdir ? MAY_CREATE_DIR : MAY_CREATE_FILE); + error = inode_permission(dir, mask | MAY_WRITE | MAY_DELETE_CHILD); + if (error && IS_RICHACL(inode)) { + /* Deleting is also permitted with MAY_EXEC on the directory + * and MAY_DELETE_SELF on the inode. */ + if (!inode_permission(inode, MAY_DELETE_SELF) && + !inode_permission(dir, mask)) + error = 0; + } if (error) return error; if (IS_APPEND(dir))
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9c44f27..abf5b0e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h@@ -83,6 +83,8 @@ typedef void (dax_iodone_t)(struct buffer_head *bh_map, int uptodate); #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
--
2.4.3