| Message ID | 20220301025052.GF117732@magnolia (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RESEND] xfs: don't generate selinux audit messages for capability testing | expand |
On Mon, Feb 28, 2022 at 06:50:52PM -0800, Darrick J. Wong wrote: > From: Darrick J. Wong <djwong@kernel.org> > > There are a few places where we test the current process' capability set > to decide if we're going to be more or less generous with resource > acquisition for a system call. If the process doesn't have the > capability, we can continue the call, albeit in a degraded mode. > > These are /not/ the actual security decisions, so it's not proper to use > capable(), which (in certain selinux setups) causes audit messages to > get logged. Switch them to has_capability_noaudit. > > Signed-off-by: Darrick J. Wong <djwong@kernel.org> > Cc: Ondrej Mosnacek <omosnace@redhat.com> > Cc: Dave Chinner <david@fromorbit.com> > --- > fs/xfs/xfs_fsmap.c | 4 ++-- > fs/xfs/xfs_ioctl.c | 2 +- > fs/xfs/xfs_iops.c | 2 +- > kernel/capability.c | 1 + > 4 files changed, 5 insertions(+), 4 deletions(-) > > diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c > index 48287caad28b..10e1cb71439e 100644 > --- a/fs/xfs/xfs_fsmap.c > +++ b/fs/xfs/xfs_fsmap.c > @@ -864,8 +864,8 @@ xfs_getfsmap( > !xfs_getfsmap_is_valid_device(mp, &head->fmh_keys[1])) > return -EINVAL; > > - use_rmap = capable(CAP_SYS_ADMIN) && > - xfs_has_rmapbt(mp); > + use_rmap = xfs_has_rmapbt(mp) && Hm, I'm failing to find where xfs_has_rmapbt() is defined. I just wanted to make sure it doesn't have any side effects that you'd want to avoid in the no-capability case. (Seems very unlikely that it would, given the name) > + has_capability_noaudit(current, CAP_SYS_ADMIN); > head->fmh_entries = 0; > > /* Set up our device handlers. */ > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c > index 2515fe8299e1..83481005317a 100644 > --- a/fs/xfs/xfs_ioctl.c > +++ b/fs/xfs/xfs_ioctl.c > @@ -1189,7 +1189,7 @@ xfs_ioctl_setattr_get_trans( > goto out_error; > > error = xfs_trans_alloc_ichange(ip, NULL, NULL, pdqp, > - capable(CAP_FOWNER), &tp); > + has_capability_noaudit(current, CAP_FOWNER), &tp); > if (error) > goto out_error; > > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c > index b79b3846e71b..a65217f787cf 100644 > --- a/fs/xfs/xfs_iops.c > +++ b/fs/xfs/xfs_iops.c > @@ -723,7 +723,7 @@ xfs_setattr_nonsize( > } > > error = xfs_trans_alloc_ichange(ip, udqp, gdqp, NULL, > - capable(CAP_FOWNER), &tp); > + has_capability_noaudit(current, CAP_FOWNER), &tp); > if (error) > goto out_dqrele; > > diff --git a/kernel/capability.c b/kernel/capability.c > index 46a361dde042..765194f5d678 100644 > --- a/kernel/capability.c > +++ b/kernel/capability.c > @@ -360,6 +360,7 @@ bool has_capability_noaudit(struct task_struct *t, int cap) > { > return has_ns_capability_noaudit(t, &init_user_ns, cap); > } > +EXPORT_SYMBOL(has_capability_noaudit); > > static bool ns_capable_common(struct user_namespace *ns, > int cap,
On Tue, Mar 01, 2022 at 09:10:14AM -0600, Serge E. Hallyn wrote: > On Mon, Feb 28, 2022 at 06:50:52PM -0800, Darrick J. Wong wrote: > > From: Darrick J. Wong <djwong@kernel.org> > > > > There are a few places where we test the current process' capability set > > to decide if we're going to be more or less generous with resource > > acquisition for a system call. If the process doesn't have the > > capability, we can continue the call, albeit in a degraded mode. > > > > These are /not/ the actual security decisions, so it's not proper to use > > capable(), which (in certain selinux setups) causes audit messages to > > get logged. Switch them to has_capability_noaudit. > > > > Signed-off-by: Darrick J. Wong <djwong@kernel.org> > > Cc: Ondrej Mosnacek <omosnace@redhat.com> > > Cc: Dave Chinner <david@fromorbit.com> > > --- > > fs/xfs/xfs_fsmap.c | 4 ++-- > > fs/xfs/xfs_ioctl.c | 2 +- > > fs/xfs/xfs_iops.c | 2 +- > > kernel/capability.c | 1 + > > 4 files changed, 5 insertions(+), 4 deletions(-) > > > > diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c > > index 48287caad28b..10e1cb71439e 100644 > > --- a/fs/xfs/xfs_fsmap.c > > +++ b/fs/xfs/xfs_fsmap.c > > @@ -864,8 +864,8 @@ xfs_getfsmap( > > !xfs_getfsmap_is_valid_device(mp, &head->fmh_keys[1])) > > return -EINVAL; > > > > - use_rmap = capable(CAP_SYS_ADMIN) && > > - xfs_has_rmapbt(mp); > > + use_rmap = xfs_has_rmapbt(mp) && > > Hm, I'm failing to find where xfs_has_rmapbt() is defined. I just > wanted to make sure it doesn't have any side effects that you'd want > to avoid in the no-capability case. (Seems very unlikely that it > would, given the name) fs/xfs/xfs_mount.h:495:__XFS_HAS_FEAT(rmapbt, RMAPBT) To expand on that a little -- it's a convenience predicate that tells us whether or not the mounted xfs filesystem supports the reverse mapping btree feature. The predicate itself has no side effects, of course, so the rearranging of the two sides of the && operator so that we do the cheaper check first (like this code probably should have done from the start). --D > > > + has_capability_noaudit(current, CAP_SYS_ADMIN); > > head->fmh_entries = 0; > > > > /* Set up our device handlers. */ > > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c > > index 2515fe8299e1..83481005317a 100644 > > --- a/fs/xfs/xfs_ioctl.c > > +++ b/fs/xfs/xfs_ioctl.c > > @@ -1189,7 +1189,7 @@ xfs_ioctl_setattr_get_trans( > > goto out_error; > > > > error = xfs_trans_alloc_ichange(ip, NULL, NULL, pdqp, > > - capable(CAP_FOWNER), &tp); > > + has_capability_noaudit(current, CAP_FOWNER), &tp); > > if (error) > > goto out_error; > > > > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c > > index b79b3846e71b..a65217f787cf 100644 > > --- a/fs/xfs/xfs_iops.c > > +++ b/fs/xfs/xfs_iops.c > > @@ -723,7 +723,7 @@ xfs_setattr_nonsize( > > } > > > > error = xfs_trans_alloc_ichange(ip, udqp, gdqp, NULL, > > - capable(CAP_FOWNER), &tp); > > + has_capability_noaudit(current, CAP_FOWNER), &tp); > > if (error) > > goto out_dqrele; > > > > diff --git a/kernel/capability.c b/kernel/capability.c > > index 46a361dde042..765194f5d678 100644 > > --- a/kernel/capability.c > > +++ b/kernel/capability.c > > @@ -360,6 +360,7 @@ bool has_capability_noaudit(struct task_struct *t, int cap) > > { > > return has_ns_capability_noaudit(t, &init_user_ns, cap); > > } > > +EXPORT_SYMBOL(has_capability_noaudit); > > > > static bool ns_capable_common(struct user_namespace *ns, > > int cap,
On Tue, Mar 1, 2022 at 3:51 AM Darrick J. Wong <djwong@kernel.org> wrote: > From: Darrick J. Wong <djwong@kernel.org> > > There are a few places where we test the current process' capability set > to decide if we're going to be more or less generous with resource > acquisition for a system call. If the process doesn't have the > capability, we can continue the call, albeit in a degraded mode. > > These are /not/ the actual security decisions, so it's not proper to use > capable(), which (in certain selinux setups) causes audit messages to > get logged. Switch them to has_capability_noaudit. > > Signed-off-by: Darrick J. Wong <djwong@kernel.org> > Cc: Ondrej Mosnacek <omosnace@redhat.com> > Cc: Dave Chinner <david@fromorbit.com> > --- > fs/xfs/xfs_fsmap.c | 4 ++-- > fs/xfs/xfs_ioctl.c | 2 +- > fs/xfs/xfs_iops.c | 2 +- > kernel/capability.c | 1 + > 4 files changed, 5 insertions(+), 4 deletions(-) > > diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c > index 48287caad28b..10e1cb71439e 100644 > --- a/fs/xfs/xfs_fsmap.c > +++ b/fs/xfs/xfs_fsmap.c > @@ -864,8 +864,8 @@ xfs_getfsmap( > !xfs_getfsmap_is_valid_device(mp, &head->fmh_keys[1])) > return -EINVAL; > > - use_rmap = capable(CAP_SYS_ADMIN) && > - xfs_has_rmapbt(mp); > + use_rmap = xfs_has_rmapbt(mp) && > + has_capability_noaudit(current, CAP_SYS_ADMIN); > head->fmh_entries = 0; > > /* Set up our device handlers. */ > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c > index 2515fe8299e1..83481005317a 100644 > --- a/fs/xfs/xfs_ioctl.c > +++ b/fs/xfs/xfs_ioctl.c > @@ -1189,7 +1189,7 @@ xfs_ioctl_setattr_get_trans( > goto out_error; > > error = xfs_trans_alloc_ichange(ip, NULL, NULL, pdqp, > - capable(CAP_FOWNER), &tp); > + has_capability_noaudit(current, CAP_FOWNER), &tp); > if (error) > goto out_error; > > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c > index b79b3846e71b..a65217f787cf 100644 > --- a/fs/xfs/xfs_iops.c > +++ b/fs/xfs/xfs_iops.c > @@ -723,7 +723,7 @@ xfs_setattr_nonsize( > } > > error = xfs_trans_alloc_ichange(ip, udqp, gdqp, NULL, > - capable(CAP_FOWNER), &tp); > + has_capability_noaudit(current, CAP_FOWNER), &tp); > if (error) > goto out_dqrele; > > diff --git a/kernel/capability.c b/kernel/capability.c > index 46a361dde042..765194f5d678 100644 > --- a/kernel/capability.c > +++ b/kernel/capability.c > @@ -360,6 +360,7 @@ bool has_capability_noaudit(struct task_struct *t, int cap) > { > return has_ns_capability_noaudit(t, &init_user_ns, cap); > } > +EXPORT_SYMBOL(has_capability_noaudit); > > static bool ns_capable_common(struct user_namespace *ns, > int cap, > Thank you for respinning the patch[1]! And sorry that I couldn't find the time to do that :/ Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com> (Yes, we should still clean up and document the capability functions, but if no one has the energy, let's at least do the minimal fix.) [1] Link for reference: https://lore.kernel.org/linux-xfs/20210316173226.2220046-1-omosnace@redhat.com/T/ -- Ondrej Mosnacek Software Engineer, Linux Security - SELinux kernel Red Hat, Inc.
On Tue, Mar 01, 2022 at 07:48:18AM -0800, Darrick J. Wong wrote: > On Tue, Mar 01, 2022 at 09:10:14AM -0600, Serge E. Hallyn wrote: > > On Mon, Feb 28, 2022 at 06:50:52PM -0800, Darrick J. Wong wrote: > > > From: Darrick J. Wong <djwong@kernel.org> > > > > > > There are a few places where we test the current process' capability set > > > to decide if we're going to be more or less generous with resource > > > acquisition for a system call. If the process doesn't have the > > > capability, we can continue the call, albeit in a degraded mode. > > > > > > These are /not/ the actual security decisions, so it's not proper to use > > > capable(), which (in certain selinux setups) causes audit messages to > > > get logged. Switch them to has_capability_noaudit. > > > > > > Signed-off-by: Darrick J. Wong <djwong@kernel.org> > > > Cc: Ondrej Mosnacek <omosnace@redhat.com> > > > Cc: Dave Chinner <david@fromorbit.com> > > > --- > > > fs/xfs/xfs_fsmap.c | 4 ++-- > > > fs/xfs/xfs_ioctl.c | 2 +- > > > fs/xfs/xfs_iops.c | 2 +- > > > kernel/capability.c | 1 + > > > 4 files changed, 5 insertions(+), 4 deletions(-) > > > > > > diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c > > > index 48287caad28b..10e1cb71439e 100644 > > > --- a/fs/xfs/xfs_fsmap.c > > > +++ b/fs/xfs/xfs_fsmap.c > > > @@ -864,8 +864,8 @@ xfs_getfsmap( > > > !xfs_getfsmap_is_valid_device(mp, &head->fmh_keys[1])) > > > return -EINVAL; > > > > > > - use_rmap = capable(CAP_SYS_ADMIN) && > > > - xfs_has_rmapbt(mp); > > > + use_rmap = xfs_has_rmapbt(mp) && > > > > Hm, I'm failing to find where xfs_has_rmapbt() is defined. I just > > wanted to make sure it doesn't have any side effects that you'd want > > to avoid in the no-capability case. (Seems very unlikely that it > > would, given the name) > > fs/xfs/xfs_mount.h:495:__XFS_HAS_FEAT(rmapbt, RMAPBT) > > To expand on that a little -- it's a convenience predicate that tells us > whether or not the mounted xfs filesystem supports the reverse mapping > btree feature. The predicate itself has no side effects, of course, so > the rearranging of the two sides of the && operator so that we do the > cheaper check first (like this code probably should have done from the > start). > > --D THank you - looks good then. Acked-by: Serge Hallyn <serge@hallyn.com> > > > > > + has_capability_noaudit(current, CAP_SYS_ADMIN); > > > head->fmh_entries = 0; > > > > > > /* Set up our device handlers. */ > > > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c > > > index 2515fe8299e1..83481005317a 100644 > > > --- a/fs/xfs/xfs_ioctl.c > > > +++ b/fs/xfs/xfs_ioctl.c > > > @@ -1189,7 +1189,7 @@ xfs_ioctl_setattr_get_trans( > > > goto out_error; > > > > > > error = xfs_trans_alloc_ichange(ip, NULL, NULL, pdqp, > > > - capable(CAP_FOWNER), &tp); > > > + has_capability_noaudit(current, CAP_FOWNER), &tp); > > > if (error) > > > goto out_error; > > > > > > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c > > > index b79b3846e71b..a65217f787cf 100644 > > > --- a/fs/xfs/xfs_iops.c > > > +++ b/fs/xfs/xfs_iops.c > > > @@ -723,7 +723,7 @@ xfs_setattr_nonsize( > > > } > > > > > > error = xfs_trans_alloc_ichange(ip, udqp, gdqp, NULL, > > > - capable(CAP_FOWNER), &tp); > > > + has_capability_noaudit(current, CAP_FOWNER), &tp); > > > if (error) > > > goto out_dqrele; > > > > > > diff --git a/kernel/capability.c b/kernel/capability.c > > > index 46a361dde042..765194f5d678 100644 > > > --- a/kernel/capability.c > > > +++ b/kernel/capability.c > > > @@ -360,6 +360,7 @@ bool has_capability_noaudit(struct task_struct *t, int cap) > > > { > > > return has_ns_capability_noaudit(t, &init_user_ns, cap); > > > } > > > +EXPORT_SYMBOL(has_capability_noaudit); > > > > > > static bool ns_capable_common(struct user_namespace *ns, > > > int cap,
On 2/28/22 8:50 PM, Darrick J. Wong wrote: > From: Darrick J. Wong <djwong@kernel.org> > > There are a few places where we test the current process' capability set > to decide if we're going to be more or less generous with resource > acquisition for a system call. If the process doesn't have the > capability, we can continue the call, albeit in a degraded mode. > > These are /not/ the actual security decisions, so it's not proper to use > capable(), which (in certain selinux setups) causes audit messages to > get logged. Switch them to has_capability_noaudit. > > Signed-off-by: Darrick J. Wong <djwong@kernel.org> > Cc: Ondrej Mosnacek <omosnace@redhat.com> > Cc: Dave Chinner <david@fromorbit.com> Thanks Darrick. This looks technically correct to me as well. You might want to add a: Fixes: 7317a03df703f ("xfs: refactor inode ownership change transaction/inode/quota allocation idiom") because I /think/ that's the commit that moved the capable() checks out from under quota tests, and made the problem more visible. And maybe: Fixes: ea9a46e1c4925 ("xfs: only return detailed fsmap info if the caller has CAP_SYS_ADMIN") as well? It's not strictly fixing the former; AFAICT the problem existed when quota was enabled already, so I'll leave all that to your discretion. Reviewed-by: Eric Sandeen <sandeen@redhat.com> Thanks, -Eric
On Thu, Mar 03, 2022 at 11:21:00AM -0600, Eric Sandeen wrote: > On 2/28/22 8:50 PM, Darrick J. Wong wrote: > > From: Darrick J. Wong <djwong@kernel.org> > > > > There are a few places where we test the current process' capability set > > to decide if we're going to be more or less generous with resource > > acquisition for a system call. If the process doesn't have the > > capability, we can continue the call, albeit in a degraded mode. > > > > These are /not/ the actual security decisions, so it's not proper to use > > capable(), which (in certain selinux setups) causes audit messages to > > get logged. Switch them to has_capability_noaudit. > > > > Signed-off-by: Darrick J. Wong <djwong@kernel.org> > > Cc: Ondrej Mosnacek <omosnace@redhat.com> > > Cc: Dave Chinner <david@fromorbit.com> > > Thanks Darrick. This looks technically correct to me as well. > > You might want to add a: > > Fixes: 7317a03df703f ("xfs: refactor inode ownership change transaction/inode/quota allocation idiom") > > because I /think/ that's the commit that moved the capable() checks out > from under quota tests, and made the problem more visible. > > And maybe: > > Fixes: ea9a46e1c4925 ("xfs: only return detailed fsmap info if the caller has CAP_SYS_ADMIN") > > as well? > > It's not strictly fixing the former; AFAICT the problem existed when quota was > enabled already, so I'll leave all that to your discretion. > > Reviewed-by: Eric Sandeen <sandeen@redhat.com> Thank you. --D > Thanks, > -Eric
diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c index 48287caad28b..10e1cb71439e 100644 --- a/fs/xfs/xfs_fsmap.c +++ b/fs/xfs/xfs_fsmap.c @@ -864,8 +864,8 @@ xfs_getfsmap( !xfs_getfsmap_is_valid_device(mp, &head->fmh_keys[1])) return -EINVAL; - use_rmap = capable(CAP_SYS_ADMIN) && - xfs_has_rmapbt(mp); + use_rmap = xfs_has_rmapbt(mp) && + has_capability_noaudit(current, CAP_SYS_ADMIN); head->fmh_entries = 0; /* Set up our device handlers. */ diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index 2515fe8299e1..83481005317a 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -1189,7 +1189,7 @@ xfs_ioctl_setattr_get_trans( goto out_error; error = xfs_trans_alloc_ichange(ip, NULL, NULL, pdqp, - capable(CAP_FOWNER), &tp); + has_capability_noaudit(current, CAP_FOWNER), &tp); if (error) goto out_error; diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index b79b3846e71b..a65217f787cf 100644 --- a/fs/xfs/xfs_iops.c +++ b/fs/xfs/xfs_iops.c @@ -723,7 +723,7 @@ xfs_setattr_nonsize( } error = xfs_trans_alloc_ichange(ip, udqp, gdqp, NULL, - capable(CAP_FOWNER), &tp); + has_capability_noaudit(current, CAP_FOWNER), &tp); if (error) goto out_dqrele; diff --git a/kernel/capability.c b/kernel/capability.c index 46a361dde042..765194f5d678 100644 --- a/kernel/capability.c +++ b/kernel/capability.c @@ -360,6 +360,7 @@ bool has_capability_noaudit(struct task_struct *t, int cap) { return has_ns_capability_noaudit(t, &init_user_ns, cap); } +EXPORT_SYMBOL(has_capability_noaudit); static bool ns_capable_common(struct user_namespace *ns, int cap,