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SubjectRe: [Patch 1/2] selinux: ajust rules for ATTR_FORCE
Date
[Sorry if this killed thread. My ISP seems to be stopping email server
now. I've read this email from web archive.]

>> @@ -2711,12 +2711,17 @@ static int selinux_inode_permission(stru
>> static int selinux_inode_setattr(struct dentry *dentry, struct iattr *iattr)
>> {
>> const struct cred *cred = current_cred();
>> + unsigned int ia_valid = iattr->ia_valid;
>>
>> - if (iattr->ia_valid & ATTR_FORCE)
>> - return 0;
>> + /* ATTR_FORCE is just used for ATTR_KILL_S[UG]ID. */
>> + if (ia_valid & ATTR_FORCE) {
>> + ia_valid &= ~(ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_MODE);
>> + if (!ia_valid)
>> + return 0;
>>
>
> So if I read this correctly, (ATTR_FORCE| ATTR_KILL_SUID|ATTR_MODE) will
> not return here, since 'ia_valid' will be ATTR_FORCE finally.
>
> I think you forgot to clear ATTR_FORCE here...

Whoops, good catch. Fortunately, it doesn't seem to have actual problem,
but it's bug obviously, and sorry for that. Fixed patch was attached.

Thanks.
--
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>


[PATCH] selinux: adjust rules for ATTR_FORCE

From: Amerigo Wang <amwang@redhat.com>

As suggested by OGAWA Hirofumi in thread: http://lkml.org/lkml/2009/8/7/132,
we should let selinux_inode_setattr() to match our ATTR_* rules.
ATTR_FORCE should not force things like ATTR_SIZE.

Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: WANG Cong <amwang@redhat.com>
[tweaks]
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
---
security/selinux/hooks.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff -puN security/selinux/hooks.c~selinux-truncate-fix security/selinux/hooks.c
--- linux-2.6/security/selinux/hooks.c~selinux-truncate-fix 2009-08-18 06:27:58.000000000 +0900
+++ linux-2.6-hirofumi/security/selinux/hooks.c 2009-08-18 16:10:50.000000000 +0900
@@ -2711,12 +2711,18 @@ static int selinux_inode_permission(stru
static int selinux_inode_setattr(struct dentry *dentry, struct iattr *iattr)
{
const struct cred *cred = current_cred();
+ unsigned int ia_valid = iattr->ia_valid;

- if (iattr->ia_valid & ATTR_FORCE)
- return 0;
+ /* ATTR_FORCE is just used for ATTR_KILL_S[UG]ID. */
+ if (ia_valid & ATTR_FORCE) {
+ ia_valid &= ~(ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_MODE |
+ ATTR_FORCE);
+ if (!ia_valid)
+ return 0;
+ }

- if (iattr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID |
- ATTR_ATIME_SET | ATTR_MTIME_SET))
+ if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID |
+ ATTR_ATIME_SET | ATTR_MTIME_SET | ATTR_TIMES_SET))
return dentry_has_perm(cred, NULL, dentry, FILE__SETATTR);

return dentry_has_perm(cred, NULL, dentry, FILE__WRITE);
_

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