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    SubjectRe: [RFC][PATCH 4/7] smack: fix label check in smack_kernel_act_as()
    On 4/27/2011 5:34 AM, Roberto Sassu wrote:
    > The function smack_kernel_act_as() must return -EINVAL if the label
    > returned by smack_from_secid() is equal to 'smack_known_invalid.smk_known',
    > which means that no entries in the 'smack_known_list' list matching the
    > security identifier given are found.

    I'll admit that the code here is wrong, but I disagree with the fix.

    smack_from_secid() will never return NULL, so the check for NULL is
    pointless. Checking for known_invalid is not right either, as the
    Smack philosophy is to return a label in all cases, as is evident
    by the behavior of smack_from_secid(). Thus, the correct change
    would be to remove the error check completely and set the new task
    value to the value obtained from smack_from_secid in all cases.

    Besides, where did the caller of this function get a secid that isn't
    going to map to a Smack label?

    > Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
    > ---
    > security/smack/smack_lsm.c | 2 +-
    > 1 files changed, 1 insertions(+), 1 deletions(-)
    >
    > diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
    > index e3c9e54..0e7ed31 100644
    > --- a/security/smack/smack_lsm.c
    > +++ b/security/smack/smack_lsm.c
    > @@ -1415,7 +1415,7 @@ static int smack_kernel_act_as(struct cred *new, u32 secid)
    > struct task_smack *new_tsp = new->security;
    > char *smack = smack_from_secid(secid);
    >
    > - if (smack == NULL)
    > + if (smack == smack_known_invalid.smk_known)
    > return -EINVAL;
    >
    > new_tsp->smk_task = smack;



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