The current way of setting and getting posix acls through the generic xattr interface is error prone and type unsafe. The vfs needs to interpret and fixup posix acls before storing or reporting it to userspace. Various hacks exist to make this work. The code is hard to understand and difficult to maintain in it's current form. Instead of making this work by hacking posix acls through xattr handlers we are building a dedicated posix acl api around the get and set inode operations. This removes a lot of hackiness and makes the codepaths easier to maintain. A lot of background can be found in [1]. So far posix acls were passed as a void blob to the security and integrity modules. Some of them like evm then proceed to interpret the void pointer and convert it into the kernel internal struct posix acl representation to perform their integrity checking magic. This is obviously pretty problematic as that requires knowledge that only the vfs is guaranteed to have and has lead to various bugs. Now that we have a proper security hook for setting posix acls that passes down the posix acls in their appropriate vfs format instead of hacking it through a void pointer stored in the uapi format make use of it in the new posix acl api. Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@xxxxxxxxxx [1] Signed-off-by: Christian Brauner (Microsoft) <brauner@xxxxxxxxxx> --- Notes: /* v2 */ unchanged fs/posix_acl.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/posix_acl.c b/fs/posix_acl.c index f19ded0978e5..471d17fa1611 100644 --- a/fs/posix_acl.c +++ b/fs/posix_acl.c @@ -24,6 +24,7 @@ #include <linux/user_namespace.h> #include <linux/namei.h> #include <linux/mnt_idmapping.h> +#include <linux/security.h> #include <linux/fsnotify.h> static struct posix_acl **acl_by_type(struct inode *inode, int type) @@ -1336,6 +1337,10 @@ int vfs_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry, if (error) goto out_inode_unlock; + error = security_inode_set_acl(mnt_userns, dentry, acl_name, kacl); + if (error) + goto out_inode_unlock; + error = try_break_deleg(inode, &delegated_inode); if (error) goto out_inode_unlock; -- 2.34.1
