| Message ID | 20240115181809.885385-15-roberto.sassu@huaweicloud.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | security: Move IMA and EVM to the LSM infrastructure | expand |
On Jan 15, 2024 Roberto Sassu <roberto.sassu@huaweicloud.com> wrote: > > In preparation for moving IMA and EVM to the LSM infrastructure, introduce > the path_post_mknod hook. > > IMA-appraisal requires all existing files in policy to have a file > hash/signature stored in security.ima. An exception is made for empty files > created by mknod, by tagging them as new files. > > LSMs could also take some action after files are created. > > The new hook cannot return an error and cannot cause the operation to be > reverted. > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> > Acked-by: Casey Schaufler <casey@schaufler-ca.com> > Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> > --- > fs/namei.c | 5 +++++ > include/linux/lsm_hook_defs.h | 2 ++ > include/linux/security.h | 5 +++++ > security/security.c | 14 ++++++++++++++ > 4 files changed, 26 insertions(+) Acked-by: Paul Moore <paul@paul-moore.com> -- paul-moore.com
On 1/15/24 13:17, Roberto Sassu wrote: > From: Roberto Sassu <roberto.sassu@huawei.com> > > In preparation for moving IMA and EVM to the LSM infrastructure, introduce > the path_post_mknod hook. > > IMA-appraisal requires all existing files in policy to have a file > hash/signature stored in security.ima. An exception is made for empty files > created by mknod, by tagging them as new files. > > LSMs could also take some action after files are created. > > The new hook cannot return an error and cannot cause the operation to be > reverted. > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> > Acked-by: Casey Schaufler <casey@schaufler-ca.com> > Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > --- > fs/namei.c | 5 +++++ > include/linux/lsm_hook_defs.h | 2 ++ > include/linux/security.h | 5 +++++ > security/security.c | 14 ++++++++++++++ > 4 files changed, 26 insertions(+) > > diff --git a/fs/namei.c b/fs/namei.c > index fb93d3e13df6..b7f433720b1e 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -4047,6 +4047,11 @@ static int do_mknodat(int dfd, struct filename *name, umode_t mode, > dentry, mode, 0); > break; > } > + > + if (error) > + goto out2; > + > + security_path_post_mknod(idmap, dentry); > out2: > done_path_create(&path, dentry); > if (retry_estale(error, lookup_flags)) { > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > index 229f84ce12ae..e08b9091350d 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -94,6 +94,8 @@ LSM_HOOK(int, 0, path_mkdir, const struct path *dir, struct dentry *dentry, > LSM_HOOK(int, 0, path_rmdir, const struct path *dir, struct dentry *dentry) > LSM_HOOK(int, 0, path_mknod, const struct path *dir, struct dentry *dentry, > umode_t mode, unsigned int dev) > +LSM_HOOK(void, LSM_RET_VOID, path_post_mknod, struct mnt_idmap *idmap, > + struct dentry *dentry) > LSM_HOOK(int, 0, path_truncate, const struct path *path) > LSM_HOOK(int, 0, path_symlink, const struct path *dir, struct dentry *dentry, > const char *old_name) > diff --git a/include/linux/security.h b/include/linux/security.h > index 2997348afcb7..977dd9f7f51a 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -1893,6 +1893,7 @@ int security_path_mkdir(const struct path *dir, struct dentry *dentry, umode_t m > int security_path_rmdir(const struct path *dir, struct dentry *dentry); > int security_path_mknod(const struct path *dir, struct dentry *dentry, umode_t mode, > unsigned int dev); > +void security_path_post_mknod(struct mnt_idmap *idmap, struct dentry *dentry); > int security_path_truncate(const struct path *path); > int security_path_symlink(const struct path *dir, struct dentry *dentry, > const char *old_name); > @@ -1927,6 +1928,10 @@ static inline int security_path_mknod(const struct path *dir, struct dentry *den > return 0; > } > > +static inline void security_path_post_mknod(struct mnt_idmap *idmap, > + struct dentry *dentry) > +{ } > + > static inline int security_path_truncate(const struct path *path) > { > return 0; > diff --git a/security/security.c b/security/security.c > index 7d10724872f8..750bfe2768d5 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -1800,6 +1800,20 @@ int security_path_mknod(const struct path *dir, struct dentry *dentry, > } > EXPORT_SYMBOL(security_path_mknod); > > +/** > + * security_path_post_mknod() - Update inode security field after file creation > + * @idmap: idmap of the mount > + * @dentry: new file > + * > + * Update inode security field after a file has been created. > + */ > +void security_path_post_mknod(struct mnt_idmap *idmap, struct dentry *dentry) > +{ > + if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) > + return; > + call_void_hook(path_post_mknod, idmap, dentry); > +} > + > /** > * security_path_mkdir() - Check if creating a new directory is allowed > * @dir: parent directory
diff --git a/fs/namei.c b/fs/namei.c index fb93d3e13df6..b7f433720b1e 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -4047,6 +4047,11 @@ static int do_mknodat(int dfd, struct filename *name, umode_t mode, dentry, mode, 0); break; } + + if (error) + goto out2; + + security_path_post_mknod(idmap, dentry); out2: done_path_create(&path, dentry); if (retry_estale(error, lookup_flags)) { diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 229f84ce12ae..e08b9091350d 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -94,6 +94,8 @@ LSM_HOOK(int, 0, path_mkdir, const struct path *dir, struct dentry *dentry, LSM_HOOK(int, 0, path_rmdir, const struct path *dir, struct dentry *dentry) LSM_HOOK(int, 0, path_mknod, const struct path *dir, struct dentry *dentry, umode_t mode, unsigned int dev) +LSM_HOOK(void, LSM_RET_VOID, path_post_mknod, struct mnt_idmap *idmap, + struct dentry *dentry) LSM_HOOK(int, 0, path_truncate, const struct path *path) LSM_HOOK(int, 0, path_symlink, const struct path *dir, struct dentry *dentry, const char *old_name) diff --git a/include/linux/security.h b/include/linux/security.h index 2997348afcb7..977dd9f7f51a 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -1893,6 +1893,7 @@ int security_path_mkdir(const struct path *dir, struct dentry *dentry, umode_t m int security_path_rmdir(const struct path *dir, struct dentry *dentry); int security_path_mknod(const struct path *dir, struct dentry *dentry, umode_t mode, unsigned int dev); +void security_path_post_mknod(struct mnt_idmap *idmap, struct dentry *dentry); int security_path_truncate(const struct path *path); int security_path_symlink(const struct path *dir, struct dentry *dentry, const char *old_name); @@ -1927,6 +1928,10 @@ static inline int security_path_mknod(const struct path *dir, struct dentry *den return 0; } +static inline void security_path_post_mknod(struct mnt_idmap *idmap, + struct dentry *dentry) +{ } + static inline int security_path_truncate(const struct path *path) { return 0; diff --git a/security/security.c b/security/security.c index 7d10724872f8..750bfe2768d5 100644 --- a/security/security.c +++ b/security/security.c @@ -1800,6 +1800,20 @@ int security_path_mknod(const struct path *dir, struct dentry *dentry, } EXPORT_SYMBOL(security_path_mknod); +/** + * security_path_post_mknod() - Update inode security field after file creation + * @idmap: idmap of the mount + * @dentry: new file + * + * Update inode security field after a file has been created. + */ +void security_path_post_mknod(struct mnt_idmap *idmap, struct dentry *dentry) +{ + if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) + return; + call_void_hook(path_post_mknod, idmap, dentry); +} + /** * security_path_mkdir() - Check if creating a new directory is allowed * @dir: parent directory