"Serge E. Hallyn" <[email protected]> writes: > Changelog: > Dec 8: Fixed bug in my check_kill_permission pointed out by > Eric Biederman. > Dec 13: Apply Eric's suggestion to pass target task into > kill_ok_by_cred() > for clarity > Dec 31: address comment by Eric Biederman: > don't need cred/tcred in check_kill_permission. > Jan 1: use const cred struct. > Jan 11: Per Bastian Blank's advice, clean up kill_ok_by_cred(). > Feb 16: kill_ok_by_cred: fix bad parentheses
Acked-by: "Eric W. Biederman" <[email protected]> > > Signed-off-by: Serge E. Hallyn <[email protected]> > --- > kernel/signal.c | 30 ++++++++++++++++++++++-------- > 1 files changed, 22 insertions(+), 8 deletions(-) > > diff --git a/kernel/signal.c b/kernel/signal.c > index 4e3cff1..ffe4bdf 100644 > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -636,13 +636,33 @@ static inline bool si_fromuser(const struct siginfo > *info) > } > > /* > + * called with RCU read lock from check_kill_permission() > + */ > +static inline int kill_ok_by_cred(struct task_struct *t) > +{ > + const struct cred *cred = current_cred(); > + const struct cred *tcred = __task_cred(t); > + > + if (cred->user->user_ns == tcred->user->user_ns && > + (cred->euid == tcred->suid || > + cred->euid == tcred->uid || > + cred->uid == tcred->suid || > + cred->uid == tcred->uid)) > + return 1; > + > + if (ns_capable(tcred->user->user_ns, CAP_KILL)) > + return 1; > + > + return 0; > +} > + > +/* > * Bad permissions for sending the signal > * - the caller must hold the RCU read lock > */ > static int check_kill_permission(int sig, struct siginfo *info, > struct task_struct *t) > { > - const struct cred *cred, *tcred; > struct pid *sid; > int error; > > @@ -656,14 +676,8 @@ static int check_kill_permission(int sig, struct siginfo > *info, > if (error) > return error; > > - cred = current_cred(); > - tcred = __task_cred(t); > if (!same_thread_group(current, t) && > - (cred->euid ^ tcred->suid) && > - (cred->euid ^ tcred->uid) && > - (cred->uid ^ tcred->suid) && > - (cred->uid ^ tcred->uid) && > - !capable(CAP_KILL)) { > + !kill_ok_by_cred(t)) { > switch (sig) { > case SIGCONT: > sid = task_session(t); _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
