| Message ID | 20190621185233.6766-19-casey@schaufler-ca.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | LSM: Module stacking for AppArmor | expand |
On Fri, Jun 21, 2019 at 11:52:27AM -0700, Casey Schaufler wrote: > Change the security_dentry_init_security() interface to > fill an lsmcontext structure instead of a void * data area > and a length. The lone caller of this interface is NFS4, > which may make copies of the data using its own mechanisms. > A rework of the nfs4 code to use the lsmcontext properly > is a significant project, so the coward's way out is taken, > and the lsmcontext data from security_dentry_init_security() > is copied, then released directly. > > Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> > --- > fs/nfs/nfs4proc.c | 26 ++++++++++++++++---------- > include/linux/security.h | 7 +++---- > security/security.c | 20 ++++++++++++++++---- > 3 files changed, 35 insertions(+), 18 deletions(-) > > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c > index af1c0db29c39..952f805965bb 100644 > --- a/fs/nfs/nfs4proc.c > +++ b/fs/nfs/nfs4proc.c > @@ -113,6 +113,7 @@ static inline struct nfs4_label * > nfs4_label_init_security(struct inode *dir, struct dentry *dentry, > struct iattr *sattr, struct nfs4_label *label) > { > + struct lsmcontext context; > int err; > > if (label == NULL) > @@ -122,21 +123,26 @@ nfs4_label_init_security(struct inode *dir, struct dentry *dentry, > return NULL; > > err = security_dentry_init_security(dentry, sattr->ia_mode, > - &dentry->d_name, (void **)&label->label, &label->len); > - if (err == 0) > - return label; > + &dentry->d_name, &context); > + > + if (err) > + return NULL; > + > + label->label = kmemdup(context.context, context.len, GFP_KERNEL); > + if (label->label == NULL) > + label = NULL; > + else > + label->len = context.len; > + > + security_release_secctx(&context); > + > + return label; > > - return NULL; > } > static inline void > nfs4_label_release_security(struct nfs4_label *label) > { > - struct lsmcontext scaff; /* scaffolding */ > - > - if (label) { > - lsmcontext_init(&scaff, label->label, label->len, 0); > - security_release_secctx(&scaff); > - } > + kfree(label->label); > } > static inline u32 *nfs4_bitmask(struct nfs_server *server, struct nfs4_label *label) > { > diff --git a/include/linux/security.h b/include/linux/security.h > index 3cbe43db16f5..2a2785a4e752 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -348,8 +348,8 @@ int security_sb_clone_mnt_opts(const struct super_block *oldsb, > int security_add_mnt_opt(const char *option, const char *val, > int len, void **mnt_opts); > int security_dentry_init_security(struct dentry *dentry, int mode, > - const struct qstr *name, void **ctx, > - u32 *ctxlen); > + const struct qstr *name, > + struct lsmcontext *ctx); > int security_dentry_create_files_as(struct dentry *dentry, int mode, > struct qstr *name, > const struct cred *old, > @@ -720,8 +720,7 @@ static inline void security_inode_free(struct inode *inode) > static inline int security_dentry_init_security(struct dentry *dentry, > int mode, > const struct qstr *name, > - void **ctx, > - u32 *ctxlen) > + struct lsmcontext *ctx) > { > return -EOPNOTSUPP; > } > diff --git a/security/security.c b/security/security.c > index f461ab3fb9c4..842ac65abc08 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -453,6 +453,8 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count, > * secid in the lsmblob structure. > */ > if (hooks[i].head == &security_hook_heads.audit_rule_match || > + hooks[i].head == > + &security_hook_heads.dentry_init_security || > hooks[i].head == &security_hook_heads.kernel_act_as || > hooks[i].head == > &security_hook_heads.socket_getpeersec_dgram || > @@ -1040,11 +1042,21 @@ void security_inode_free(struct inode *inode) > } > > int security_dentry_init_security(struct dentry *dentry, int mode, > - const struct qstr *name, void **ctx, > - u32 *ctxlen) > + const struct qstr *name, > + struct lsmcontext *cp) > { > - return call_int_hook(dentry_init_security, -EOPNOTSUPP, dentry, mode, > - name, ctx, ctxlen); > + int *display = current->security; > + struct security_hook_list *hp; > + > + hlist_for_each_entry(hp, &security_hook_heads.dentry_init_security, > + list) > + if (*display == 0 || *display == hp->slot) { Is this supposed to be == -1 not 0? Isn't 0 an assigned slot? Otherwise: Reviewed-by: Kees Cook <keescook@chromium.org> -Kees > + cp->slot = hp->slot; > + return hp->hook.dentry_init_security(dentry, mode, > + name, (void **)&cp->context, &cp->len); > + } > + > + return -EOPNOTSUPP; > } > EXPORT_SYMBOL(security_dentry_init_security); > > -- > 2.20.1 >
On 6/21/19 11:52 AM, Casey Schaufler wrote: > Change the security_dentry_init_security() interface to > fill an lsmcontext structure instead of a void * data area > and a length. The lone caller of this interface is NFS4, > which may make copies of the data using its own mechanisms. > A rework of the nfs4 code to use the lsmcontext properly > is a significant project, so the coward's way out is taken, > and the lsmcontext data from security_dentry_init_security() > is copied, then released directly. > > Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> With the needed fix (below) that Kees already pointed out Reviewed-by: John Johansen <john.johansen@canonical.com> > --- > fs/nfs/nfs4proc.c | 26 ++++++++++++++++---------- > include/linux/security.h | 7 +++---- > security/security.c | 20 ++++++++++++++++---- > 3 files changed, 35 insertions(+), 18 deletions(-) > > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c > index af1c0db29c39..952f805965bb 100644 > --- a/fs/nfs/nfs4proc.c > +++ b/fs/nfs/nfs4proc.c > @@ -113,6 +113,7 @@ static inline struct nfs4_label * > nfs4_label_init_security(struct inode *dir, struct dentry *dentry, > struct iattr *sattr, struct nfs4_label *label) > { > + struct lsmcontext context; > int err; > > if (label == NULL) > @@ -122,21 +123,26 @@ nfs4_label_init_security(struct inode *dir, struct dentry *dentry, > return NULL; > > err = security_dentry_init_security(dentry, sattr->ia_mode, > - &dentry->d_name, (void **)&label->label, &label->len); > - if (err == 0) > - return label; > + &dentry->d_name, &context); > + > + if (err) > + return NULL; > + > + label->label = kmemdup(context.context, context.len, GFP_KERNEL); > + if (label->label == NULL) > + label = NULL; > + else > + label->len = context.len; > + > + security_release_secctx(&context); > + > + return label; > > - return NULL; > } > static inline void > nfs4_label_release_security(struct nfs4_label *label) > { > - struct lsmcontext scaff; /* scaffolding */ > - > - if (label) { > - lsmcontext_init(&scaff, label->label, label->len, 0); > - security_release_secctx(&scaff); > - } > + kfree(label->label); > } > static inline u32 *nfs4_bitmask(struct nfs_server *server, struct nfs4_label *label) > { > diff --git a/include/linux/security.h b/include/linux/security.h > index 3cbe43db16f5..2a2785a4e752 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -348,8 +348,8 @@ int security_sb_clone_mnt_opts(const struct super_block *oldsb, > int security_add_mnt_opt(const char *option, const char *val, > int len, void **mnt_opts); > int security_dentry_init_security(struct dentry *dentry, int mode, > - const struct qstr *name, void **ctx, > - u32 *ctxlen); > + const struct qstr *name, > + struct lsmcontext *ctx); > int security_dentry_create_files_as(struct dentry *dentry, int mode, > struct qstr *name, > const struct cred *old, > @@ -720,8 +720,7 @@ static inline void security_inode_free(struct inode *inode) > static inline int security_dentry_init_security(struct dentry *dentry, > int mode, > const struct qstr *name, > - void **ctx, > - u32 *ctxlen) > + struct lsmcontext *ctx) > { > return -EOPNOTSUPP; > } > diff --git a/security/security.c b/security/security.c > index f461ab3fb9c4..842ac65abc08 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -453,6 +453,8 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count, > * secid in the lsmblob structure. > */ > if (hooks[i].head == &security_hook_heads.audit_rule_match || > + hooks[i].head == > + &security_hook_heads.dentry_init_security || > hooks[i].head == &security_hook_heads.kernel_act_as || > hooks[i].head == > &security_hook_heads.socket_getpeersec_dgram || > @@ -1040,11 +1042,21 @@ void security_inode_free(struct inode *inode) > } > > int security_dentry_init_security(struct dentry *dentry, int mode, > - const struct qstr *name, void **ctx, > - u32 *ctxlen) > + const struct qstr *name, > + struct lsmcontext *cp) > { > - return call_int_hook(dentry_init_security, -EOPNOTSUPP, dentry, mode, > - name, ctx, ctxlen); > + int *display = current->security; > + struct security_hook_list *hp; > + > + hlist_for_each_entry(hp, &security_hook_heads.dentry_init_security, > + list) > + if (*display == 0 || *display == hp->slot) { > + cp->slot = hp->slot; > + return hp->hook.dentry_init_security(dentry, mode, > + name, (void **)&cp->context, &cp->len); > + } > + should be if (*display == LSMBLOB_INVALID || *display == hp->slot) > + return -EOPNOTSUPP; > } > EXPORT_SYMBOL(security_dentry_init_security); > >
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index af1c0db29c39..952f805965bb 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -113,6 +113,7 @@ static inline struct nfs4_label * nfs4_label_init_security(struct inode *dir, struct dentry *dentry, struct iattr *sattr, struct nfs4_label *label) { + struct lsmcontext context; int err; if (label == NULL) @@ -122,21 +123,26 @@ nfs4_label_init_security(struct inode *dir, struct dentry *dentry, return NULL; err = security_dentry_init_security(dentry, sattr->ia_mode, - &dentry->d_name, (void **)&label->label, &label->len); - if (err == 0) - return label; + &dentry->d_name, &context); + + if (err) + return NULL; + + label->label = kmemdup(context.context, context.len, GFP_KERNEL); + if (label->label == NULL) + label = NULL; + else + label->len = context.len; + + security_release_secctx(&context); + + return label; - return NULL; } static inline void nfs4_label_release_security(struct nfs4_label *label) { - struct lsmcontext scaff; /* scaffolding */ - - if (label) { - lsmcontext_init(&scaff, label->label, label->len, 0); - security_release_secctx(&scaff); - } + kfree(label->label); } static inline u32 *nfs4_bitmask(struct nfs_server *server, struct nfs4_label *label) { diff --git a/include/linux/security.h b/include/linux/security.h index 3cbe43db16f5..2a2785a4e752 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -348,8 +348,8 @@ int security_sb_clone_mnt_opts(const struct super_block *oldsb, int security_add_mnt_opt(const char *option, const char *val, int len, void **mnt_opts); int security_dentry_init_security(struct dentry *dentry, int mode, - const struct qstr *name, void **ctx, - u32 *ctxlen); + const struct qstr *name, + struct lsmcontext *ctx); int security_dentry_create_files_as(struct dentry *dentry, int mode, struct qstr *name, const struct cred *old, @@ -720,8 +720,7 @@ static inline void security_inode_free(struct inode *inode) static inline int security_dentry_init_security(struct dentry *dentry, int mode, const struct qstr *name, - void **ctx, - u32 *ctxlen) + struct lsmcontext *ctx) { return -EOPNOTSUPP; } diff --git a/security/security.c b/security/security.c index f461ab3fb9c4..842ac65abc08 100644 --- a/security/security.c +++ b/security/security.c @@ -453,6 +453,8 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count, * secid in the lsmblob structure. */ if (hooks[i].head == &security_hook_heads.audit_rule_match || + hooks[i].head == + &security_hook_heads.dentry_init_security || hooks[i].head == &security_hook_heads.kernel_act_as || hooks[i].head == &security_hook_heads.socket_getpeersec_dgram || @@ -1040,11 +1042,21 @@ void security_inode_free(struct inode *inode) } int security_dentry_init_security(struct dentry *dentry, int mode, - const struct qstr *name, void **ctx, - u32 *ctxlen) + const struct qstr *name, + struct lsmcontext *cp) { - return call_int_hook(dentry_init_security, -EOPNOTSUPP, dentry, mode, - name, ctx, ctxlen); + int *display = current->security; + struct security_hook_list *hp; + + hlist_for_each_entry(hp, &security_hook_heads.dentry_init_security, + list) + if (*display == 0 || *display == hp->slot) { + cp->slot = hp->slot; + return hp->hook.dentry_init_security(dentry, mode, + name, (void **)&cp->context, &cp->len); + } + + return -EOPNOTSUPP; } EXPORT_SYMBOL(security_dentry_init_security);
Change the security_dentry_init_security() interface to fill an lsmcontext structure instead of a void * data area and a length. The lone caller of this interface is NFS4, which may make copies of the data using its own mechanisms. A rework of the nfs4 code to use the lsmcontext properly is a significant project, so the coward's way out is taken, and the lsmcontext data from security_dentry_init_security() is copied, then released directly. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> --- fs/nfs/nfs4proc.c | 26 ++++++++++++++++---------- include/linux/security.h | 7 +++---- security/security.c | 20 ++++++++++++++++---- 3 files changed, 35 insertions(+), 18 deletions(-)