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selinux: revert "stop passing MAY_NOT_BLOCK to the AVC upon follow_link"

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commit 1a37079c23 upstream.

This reverts commit e46e01eebb ("selinux: stop passing MAY_NOT_BLOCK
to the AVC upon follow_link"). The correct fix is to instead fall
back to ref-walk if audit is required irrespective of the specific
audit data type.  This is done in the next commit.

Fixes: e46e01eebb ("selinux: stop passing MAY_NOT_BLOCK to the AVC upon follow_link")
Reported-by: Will Deacon <will@kernel.org>
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Stephen Smalley 2019-11-22 12:22:44 -05:00 committed by Greg Kroah-Hartman
parent 837c36e045
commit 3b2e595dfe
3 changed files with 30 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

24
security/selinux/avc.c
View file

@ -862,8 +862,9 @@ 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_permission for the MAY_NOT_BLOCK flag,
* which is transliterated into AVC_NONBLOCKING.
* 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().
*/
if (flags & AVC_NONBLOCKING)
return 0;
@ -1205,6 +1206,25 @@ 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;

5
security/selinux/hooks.c
View file

@ -3008,8 +3008,9 @@ static int selinux_inode_follow_link(struct dentry *dentry, struct inode *inode,
if (IS_ERR(isec))
return PTR_ERR(isec);
return avc_has_perm(&selinux_state,
sid, isec->sid, isec->sclass, FILE__READ, &ad);
return avc_has_perm_flags(&selinux_state,
sid, isec->sid, isec->sclass, FILE__READ, &ad,
rcu ? MAY_NOT_BLOCK : 0);
}
static noinline int audit_inode_permission(struct inode *inode,

5
security/selinux/include/avc.h
View file

@ -153,6 +153,11 @@ 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,