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    SubjectRe: [PATCH v2 18/25] security: Introduce inode_post_set_acl hook
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    On 8/31/2023 3:41 AM, Roberto Sassu wrote:
    > From: Roberto Sassu <roberto.sassu@huawei.com>
    >
    > In preparation for moving IMA and EVM to the LSM infrastructure, introduce
    > the inode_post_set_acl hook.

    Repeat of new LSM hook general comment:
    Would you please include some explanation of how an LSM would use this hook?
    You might start with a description of how it is used in IMA/EVM, and why that
    could be generally useful.


    >
    > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
    > Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
    > ---
    > fs/posix_acl.c | 1 +
    > include/linux/lsm_hook_defs.h | 2 ++
    > include/linux/security.h | 7 +++++++
    > security/security.c | 17 +++++++++++++++++
    > 4 files changed, 27 insertions(+)
    >
    > diff --git a/fs/posix_acl.c b/fs/posix_acl.c
    > index 7fa1b738bbab..3b7dbea5c3ff 100644
    > --- a/fs/posix_acl.c
    > +++ b/fs/posix_acl.c
    > @@ -1137,6 +1137,7 @@ int vfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
    > error = -EIO;
    > if (!error) {
    > fsnotify_xattr(dentry);
    > + security_inode_post_set_acl(dentry, acl_name, kacl);
    > evm_inode_post_set_acl(dentry, acl_name, kacl);
    > }
    >
    > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
    > index 9ae573b83737..bba1fbd97207 100644
    > --- a/include/linux/lsm_hook_defs.h
    > +++ b/include/linux/lsm_hook_defs.h
    > @@ -157,6 +157,8 @@ LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry,
    > const char *name)
    > LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap,
    > struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
    > +LSM_HOOK(void, LSM_RET_VOID, inode_post_set_acl, struct dentry *dentry,
    > + const char *acl_name, struct posix_acl *kacl)
    > LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap,
    > struct dentry *dentry, const char *acl_name)
    > LSM_HOOK(int, 0, inode_remove_acl, struct mnt_idmap *idmap,
    > diff --git a/include/linux/security.h b/include/linux/security.h
    > index 5f296761883f..556d019ebe5c 100644
    > --- a/include/linux/security.h
    > +++ b/include/linux/security.h
    > @@ -367,6 +367,8 @@ int security_inode_setxattr(struct mnt_idmap *idmap,
    > int security_inode_set_acl(struct mnt_idmap *idmap,
    > struct dentry *dentry, const char *acl_name,
    > struct posix_acl *kacl);
    > +void security_inode_post_set_acl(struct dentry *dentry, const char *acl_name,
    > + struct posix_acl *kacl);
    > int security_inode_get_acl(struct mnt_idmap *idmap,
    > struct dentry *dentry, const char *acl_name);
    > int security_inode_remove_acl(struct mnt_idmap *idmap,
    > @@ -894,6 +896,11 @@ static inline int security_inode_set_acl(struct mnt_idmap *idmap,
    > return 0;
    > }
    >
    > +static inline void security_inode_post_set_acl(struct dentry *dentry,
    > + const char *acl_name,
    > + struct posix_acl *kacl)
    > +{ }
    > +
    > static inline int security_inode_get_acl(struct mnt_idmap *idmap,
    > struct dentry *dentry,
    > const char *acl_name)
    > diff --git a/security/security.c b/security/security.c
    > index e5acb11f6ebd..4392fd878d58 100644
    > --- a/security/security.c
    > +++ b/security/security.c
    > @@ -2260,6 +2260,23 @@ int security_inode_set_acl(struct mnt_idmap *idmap,
    > return evm_inode_set_acl(idmap, dentry, acl_name, kacl);
    > }
    >
    > +/**
    > + * security_inode_post_set_acl() - Update inode security after set_acl()
    > + * @dentry: file
    > + * @acl_name: acl name
    > + * @kacl: acl struct
    > + *
    > + * Update inode security field after successful set_acl operation on @dentry.
    > + * The posix acls in @kacl are identified by @acl_name.
    > + */
    > +void security_inode_post_set_acl(struct dentry *dentry, const char *acl_name,
    > + struct posix_acl *kacl)
    > +{
    > + if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
    > + return;
    > + call_void_hook(inode_post_set_acl, dentry, acl_name, kacl);
    > +}
    > +
    > /**
    > * security_inode_get_acl() - Check if reading posix acls is allowed
    > * @idmap: idmap of the mount

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