Messages in this thread | | | Date | Fri, 30 Oct 2009 08:51:52 +1100 (EST) | From | James Morris <> | Subject | Re: [PATCH] define convenient securebits masks for prctl users (v2) |
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On Thu, 29 Oct 2009, Serge E. Hallyn wrote:
> Hi James, would you mind taking the following into > security-testing?
Applied to git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6#next
> > The securebits are used by passing them to prctl with the > PR_{S,G}ET_SECUREBITS commands. But the defines must be > shifted to be used in prctl, which begs to be confused and > misused by userspace. So define some more convenient > values for userspace to specify. This way userspace does > > prctl(PR_SET_SECUREBITS, SECBIT_NOROOT); > > instead of > > prctl(PR_SET_SECUREBITS, 1 << SECURE_NOROOT); > > (Thanks to Michael for the idea) > > This patch also adds include/linux/securebits to the installed headers. > Then perhaps it can be included by glibc's sys/prctl.h. > > Changelog: > Oct 29: Stephen Rothwell points out that issecure can > be under __KERNEL__. > Oct 14: (Suggestions by Michael Kerrisk): > 1. spell out SETUID in SECBIT_NO_SETUID* > 2. SECBIT_X_LOCKED does not imply SECBIT_X > 3. add definitions for keepcaps > Oct 14: As suggested by Michael Kerrisk, don't > use SB_* as that convention is already in > use. Use SECBIT_ prefix instead. > > Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> > Acked-by: Andrew G. Morgan <morgan@kernel.org> > Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> > Cc: Ulrich Drepper <drepper@redhat.com> > Cc: James Morris <jmorris@namei.org> > --- > include/linux/Kbuild | 1 + > include/linux/securebits.h | 24 ++++++++++++++++++------ > 2 files changed, 19 insertions(+), 6 deletions(-) > > diff --git a/include/linux/Kbuild b/include/linux/Kbuild > index 1feed71..5a53857 100644 > --- a/include/linux/Kbuild > +++ b/include/linux/Kbuild > @@ -330,6 +330,7 @@ unifdef-y += scc.h > unifdef-y += sched.h > unifdef-y += screen_info.h > unifdef-y += sdla.h > +unifdef-y += securebits.h > unifdef-y += selinux_netlink.h > unifdef-y += sem.h > unifdef-y += serial_core.h > diff --git a/include/linux/securebits.h b/include/linux/securebits.h > index d2c5ed8..3340617 100644 > --- a/include/linux/securebits.h > +++ b/include/linux/securebits.h > @@ -1,6 +1,15 @@ > #ifndef _LINUX_SECUREBITS_H > #define _LINUX_SECUREBITS_H 1 > > +/* Each securesetting is implemented using two bits. One bit specifies > + whether the setting is on or off. The other bit specify whether the > + setting is locked or not. A setting which is locked cannot be > + changed from user-level. */ > +#define issecure_mask(X) (1 << (X)) > +#ifdef __KERNEL__ > +#define issecure(X) (issecure_mask(X) & current_cred_xxx(securebits)) > +#endif > + > #define SECUREBITS_DEFAULT 0x00000000 > > /* When set UID 0 has no special privileges. When unset, we support > @@ -12,6 +21,9 @@ > #define SECURE_NOROOT 0 > #define SECURE_NOROOT_LOCKED 1 /* make bit-0 immutable */ > > +#define SECBIT_NOROOT (issecure_mask(SECURE_NOROOT)) > +#define SECBIT_NOROOT_LOCKED (issecure_mask(SECURE_NOROOT_LOCKED)) > + > /* When set, setuid to/from uid 0 does not trigger capability-"fixup". > When unset, to provide compatiblility with old programs relying on > set*uid to gain/lose privilege, transitions to/from uid 0 cause > @@ -19,6 +31,10 @@ > #define SECURE_NO_SETUID_FIXUP 2 > #define SECURE_NO_SETUID_FIXUP_LOCKED 3 /* make bit-2 immutable */ > > +#define SECBIT_NO_SETUID_FIXUP (issecure_mask(SECURE_NO_SETUID_FIXUP)) > +#define SECBIT_NO_SETUID_FIXUP_LOCKED \ > + (issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)) > + > /* When set, a process can retain its capabilities even after > transitioning to a non-root user (the set-uid fixup suppressed by > bit 2). Bit-4 is cleared when a process calls exec(); setting both > @@ -27,12 +43,8 @@ > #define SECURE_KEEP_CAPS 4 > #define SECURE_KEEP_CAPS_LOCKED 5 /* make bit-4 immutable */ > > -/* Each securesetting is implemented using two bits. One bit specifies > - whether the setting is on or off. The other bit specify whether the > - setting is locked or not. A setting which is locked cannot be > - changed from user-level. */ > -#define issecure_mask(X) (1 << (X)) > -#define issecure(X) (issecure_mask(X) & current_cred_xxx(securebits)) > +#define SECBIT_KEEP_CAPS (issecure_mask(SECURE_KEEP_CAPS)) > +#define SECBIT_KEEP_CAPS_LOCKED (issecure_mask(SECURE_KEEP_CAPS_LOCKED)) > > #define SECURE_ALL_BITS (issecure_mask(SECURE_NOROOT) | \ > issecure_mask(SECURE_NO_SETUID_FIXUP) | \ > -- > 1.6.1 >
-- James Morris <jmorris@namei.org>
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