Messages in this thread | | | Date | Tue, 5 Sep 2023 14:48:03 -0400 | Subject | Re: [PATCH v3 16/25] security: Introduce path_post_mknod hook | From | Stefan Berger <> |
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On 9/4/23 09:34, 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. > > It is useful for IMA to let new empty files be subsequently opened for > further modification. > > LSMs can benefit from this hook to update the inode state after a file has > been successfully created. The new hook cannot return an error and cannot > cause the operation to be canceled. > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> > --- > fs/namei.c | 5 +++++ > include/linux/lsm_hook_defs.h | 3 +++ > include/linux/security.h | 9 +++++++++ > security/security.c | 19 +++++++++++++++++++ > 4 files changed, 36 insertions(+) > > diff --git a/fs/namei.c b/fs/namei.c > index 7dc4626859f0..c8c4ab26b52a 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -4061,6 +4061,11 @@ static int do_mknodat(int dfd, struct filename *name, umode_t mode, > dentry, mode, 0); > break; > } > +
Nit: remove empty line.
> + if (error) > + goto out2; > + > + security_path_post_mknod(idmap, &path, dentry, mode_stripped, dev); > 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 797f51da3f7d..b1634b5de98c 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -93,6 +93,9 @@ 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, > + const struct path *dir, struct dentry *dentry, umode_t mode, > + unsigned int dev) > 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 7871009d59ae..f210bd66e939 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -1842,6 +1842,9 @@ 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, const struct path *dir, > + struct dentry *dentry, umode_t mode, > + unsigned int dev); > int security_path_truncate(const struct path *path); > int security_path_symlink(const struct path *dir, struct dentry *dentry, > const char *old_name); > @@ -1876,6 +1879,12 @@ 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, > + const struct path *dir, > + struct dentry *dentry, umode_t mode, > + unsigned int dev) > +{ } > + > static inline int security_path_truncate(const struct path *path) > { > return 0; > diff --git a/security/security.c b/security/security.c > index fbb58eeeea02..78aeb24efedb 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -1702,6 +1702,25 @@ 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 > + * @dir: parent directory > + * @dentry: new file > + * @mode: new file mode > + * @dev: device number > + * > + * Update inode security field after a file has been created. > + */ > +void security_path_post_mknod(struct mnt_idmap *idmap, const struct path *dir, > + struct dentry *dentry, umode_t mode, > + unsigned int dev) > +{ > + if (unlikely(IS_PRIVATE(d_backing_inode(dir->dentry)))) > + return; > + call_void_hook(path_post_mknod, idmap, dir, dentry, mode, dev); > +} > + > /** > * security_path_mkdir() - Check if creating a new directory is allowed > * @dir: parent directory
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
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