On 03/10/2017 11:54 AM, Paul Moore wrote:
> On Fri, Mar 10, 2017 at 12:14 PM, Stephen Smalley <sds@xxxxxxxxxxxxx> wrote:
>> generic_permission() presently checks CAP_DAC_OVERRIDE prior to
>> CAP_DAC_READ_SEARCH. This can cause misleading audit messages when
>> using a LSM such as SELinux or AppArmor, since CAP_DAC_OVERRIDE
>> may not be required for the operation. Flip the order of the
>> tests so that CAP_DAC_OVERRIDE is only checked when required for
>> the operation.
>>
>> Signed-off-by: Stephen Smalley <sds@xxxxxxxxxxxxx>
>> ---
>> fs/namei.c | 20 ++++++++++----------
>> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> This is the second posting of this patch and so far no comment ... if
> I don't see any negative responses by next week I'll go ahead and
> merge this into the selinux/next tree.
>
sounds good to me, the patch looks good you can have my acked-by for how
this affects apparmor, or hrmm should that be a reviewed-by for the vfs
end
Acked-by: John Johansen <john.johansen@xxxxxxxxxxxxx>
>> diff --git a/fs/namei.c b/fs/namei.c
>> index d41fab7..482414a 100644
>> --- a/fs/namei.c
>> +++ b/fs/namei.c
>> @@ -340,22 +340,14 @@ int generic_permission(struct inode *inode, int mask)
>>
>> if (S_ISDIR(inode->i_mode)) {
>> /* DACs are overridable for directories */
>> - if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
>> - return 0;
>> if (!(mask & MAY_WRITE))
>> if (capable_wrt_inode_uidgid(inode,
>> CAP_DAC_READ_SEARCH))
>> return 0;
>> - return -EACCES;
>> - }
>> - /*
>> - * Read/write DACs are always overridable.
>> - * Executable DACs are overridable when there is
>> - * at least one exec bit set.
>> - */
>> - if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
>> if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
>> return 0;
>> + return -EACCES;
>> + }
>>
>> /*
>> * Searching includes executable on directories, else just read.
>> @@ -364,6 +356,14 @@ int generic_permission(struct inode *inode, int mask)
>> if (mask == MAY_READ)
>> if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH))
>> return 0;
>> + /*
>> + * Read/write DACs are always overridable.
>> + * Executable DACs are overridable when there is
>> + * at least one exec bit set.
>> + */
>> + if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
>> + if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
>> + return 0;
>>
>> return -EACCES;
>> }
>> --
>> 2.7.4
>>
>
>
>
