On Wed, Dec 12, 2018 at 10:08 AM Stephen Smalley <sds@xxxxxxxxxxxxx> wrote:
> commit bda0be7ad9948 ("security: make inode_follow_link RCU-walk aware")
> switched selinux_inode_follow_link() to use avc_has_perm_flags() and
> pass down the MAY_NOT_BLOCK flag if called during RCU walk. However,
> the only test of MAY_NOT_BLOCK occurs during slow_avc_audit()
> and only if passing an inode as audit data (LSM_AUDIT_DATA_INODE). Since
> selinux_inode_follow_link() passes a dentry directly, passing MAY_NOT_BLOCK
> here serves no purpose. Switch selinux_inode_follow_link() to use
> avc_has_perm() and drop avc_has_perm_flags() since there are no other
> users.
>
> Signed-off-by: Stephen Smalley <sds@xxxxxxxxxxxxx>
> ---
> security/selinux/avc.c | 24 ++----------------------
> security/selinux/hooks.c | 5 ++---
> security/selinux/include/avc.h | 5 -----
> 3 files changed, 4 insertions(+), 30 deletions(-)
I just merged both 1/2 and 2/2 into selinux/next, thanks Stephen.
> diff --git a/security/selinux/avc.c b/security/selinux/avc.c
> index 5de18a6d5c3f..9b63d8ee1687 100644
> --- a/security/selinux/avc.c
> +++ b/security/selinux/avc.c
> @@ -867,9 +867,8 @@ static int avc_update_node(struct selinux_avc *avc,
> * permissive mode that only appear when in enforcing mode.
> *
> * See the corresponding handling in slow_avc_audit(), and the
> - * logic in selinux_inode_follow_link and selinux_inode_permission
> - * for the VFS MAY_NOT_BLOCK flag, which is transliterated into
> - * AVC_NONBLOCKING for avc_has_perm_noaudit().
> + * logic in selinux_inode_permission for the MAY_NOT_BLOCK flag,
> + * which is transliterated into AVC_NONBLOCKING.
> */
> if (flags & AVC_NONBLOCKING)
> return 0;
> @@ -1209,25 +1208,6 @@ int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass,
> return rc;
> }
>
> -int avc_has_perm_flags(struct selinux_state *state,
> - u32 ssid, u32 tsid, u16 tclass, u32 requested,
> - struct common_audit_data *auditdata,
> - int flags)
> -{
> - struct av_decision avd;
> - int rc, rc2;
> -
> - rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested,
> - (flags & MAY_NOT_BLOCK) ? AVC_NONBLOCKING : 0,
> - &avd);
> -
> - rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
> - auditdata, flags);
> - if (rc2)
> - return rc2;
> - return rc;
> -}
> -
> u32 avc_policy_seqno(struct selinux_state *state)
> {
> return state->avc->avc_cache.latest_notif;
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 9b05f84808d9..f012d2eb159e 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -3139,9 +3139,8 @@ static int selinux_inode_follow_link(struct dentry *dentry, struct inode *inode,
> if (IS_ERR(isec))
> return PTR_ERR(isec);
>
> - return avc_has_perm_flags(&selinux_state,
> - sid, isec->sid, isec->sclass, FILE__READ, &ad,
> - rcu ? MAY_NOT_BLOCK : 0);
> + return avc_has_perm(&selinux_state,
> + sid, isec->sid, isec->sclass, FILE__READ, &ad);
> }
>
> static noinline int audit_inode_permission(struct inode *inode,
> diff --git a/security/selinux/include/avc.h b/security/selinux/include/avc.h
> index 74ea50977c20..7be0e1e90e8b 100644
> --- a/security/selinux/include/avc.h
> +++ b/security/selinux/include/avc.h
> @@ -153,11 +153,6 @@ int avc_has_perm(struct selinux_state *state,
> u32 ssid, u32 tsid,
> u16 tclass, u32 requested,
> struct common_audit_data *auditdata);
> -int avc_has_perm_flags(struct selinux_state *state,
> - u32 ssid, u32 tsid,
> - u16 tclass, u32 requested,
> - struct common_audit_data *auditdata,
> - int flags);
>
> int avc_has_extended_perms(struct selinux_state *state,
> u32 ssid, u32 tsid, u16 tclass, u32 requested,
> --
> 2.19.2
>
--
paul moore
www.paul-moore.com
