panic_cpu shared variable. I used a simple atomic operation here instead
of a spin lock as it seemed to be excessive overhead. Also, this can avoid
recursive panics if, for example, witness is broken.
can happen if witness runs out of resources during initialization or if
witness_skipspin is enabled.
Sleuthing by: Peter Jeremy <peter.jeremy@alcatel.com.au>
"inside" of locked regions. That is, an acquire atomic operation will
always enforce a memory barrier after the atomic operation and a release
operation will always enforce a memory barrier before the atomic
operation.
- Explicitly use 'mb' instead of 'wmb' in release atomic operations. The
'wmb' memory barrier is not strong enough to guarantee coherence with
other processors. This is effectively a nop since alpha_wmb() actually
performs a 'mb' and not a 'wmb', but I wanted the code to be more
correct since at some point in the future alpha_wmb()'s implementation
may switch to being a real 'wmb'.
we should call ast(). This allows us to branch to a separate Lkernelret
label so we can fixup the saved t7 register in the trapframe. Otherwise
we can run into a problem on SMP systems where a process is interrupted by
a trap or interrupt on one CPU, migrates to another CPU, and then returns
with the t7 in the stack clobbering the CPU's t7. As a result, two CPU's
would both point to the same per-CPU data and things would go downhill from
there.
Sleuthing help by: gallatin
- Add a new ddb command: 'show pcpu' similar to the i386 command added
recently. By default it displays the current CPU's info, but an optional
argument can specify the logical ID of a specific CPU to examine.
bcopy would go off the end of the array by two elements, which sometimes
causes a panic if it happens to cross into a page that isn't mapped.
Submitted by: gibbs
Reviewed by: peter
are some good reasons for not doing this, even if the linting of
the code breaks.
1) If lint were ever to understand the stuff inside the macros,
that would break the checks.
2) There are ways to use __GNUC__ to exclude overly specific
code.
3) (Not yet practical) Lint(1) needs to properlyu understand
all of te code we actually run.
Complained about by: bde
Education by: jake, jhb, eivind
It is described in ufs/ffs/fs.h as follows:
/*
* Filesystem flags.
*
* Note that the FS_NEEDSFSCK flag is set and cleared only by the
* fsck utility. It is set when background fsck finds an unexpected
* inconsistency which requires a traditional foreground fsck to be
* run. Such inconsistencies should only be found after an uncorrectable
* disk error. A foreground fsck will clear the FS_NEEDSFSCK flag when
* it has successfully cleaned up the filesystem. The kernel uses this
* flag to enforce that inconsistent filesystems be mounted read-only.
*/
#define FS_UNCLEAN 0x01 /* filesystem not clean at mount */
#define FS_DOSOFTDEP 0x02 /* filesystem using soft dependencies */
#define FS_NEEDSFSCK 0x04 /* filesystem needs sync fsck before mount */
and non-P_SUGID cases, simplify p_cansignal() logic so that the
P_SUGID masking of possible signals is independent from uid checks,
removing redundant code and generally improving readability.
Reviewed by: tmm
Obtained from: TrustedBSD Project
the ability of unprivileged processes to deliver arbitrary signals
to daemons temporarily taking on unprivileged effective credentials
when P_SUGID is not set on the target process:
Removed:
(p1->p_cred->cr_ruid != ps->p_cred->cr_uid)
(p1->p_ucred->cr_uid != ps->p_cred->cr_uid)
o Replace two "allow this" exceptions in p_cansignal() restricting
the ability of unprivileged processes to deliver arbitrary signals
to daemons temporarily taking on unprivileged effective credentials
when P_SUGID is set on the target process:
Replaced:
(p1->p_cred->p_ruid != p2->p_ucred->cr_uid)
(p1->p_cred->cr_uid != p2->p_ucred->cr_uid)
With:
(p1->p_cred->p_ruid != p2->p_ucred->p_svuid)
(p1->p_ucred->cr_uid != p2->p_ucred->p_svuid)
o These changes have the effect of making the uid-based handling of
both P_SUGID and non-P_SUGID signal delivery consistent, following
these four general cases:
p1's ruid equals p2's ruid
p1's euid equals p2's ruid
p1's ruid equals p2's svuid
p1's euid equals p2's svuid
The P_SUGID and non-P_SUGID cases can now be largely collapsed,
and I'll commit this in a few days if no immediate problems are
encountered with this set of changes.
o These changes remove a number of warning cases identified by the
proc_to_proc inter-process authorization regression test.
o As these are new restrictions, we'll have to watch out carefully for
possible side effects on running code: they seem reasonable to me,
but it's possible this change might have to be backed out if problems
are experienced.
Submitted by: src/tools/regression/security/proc_to_proc/testuid
Reviewed by: tmm
Obtained from: TrustedBSD Project
ability of unprivileged processes to modify the scheduling properties
of daemons temporarily taking on unprivileged effective credentials.
These cases (p1->p_cred->p_ruid == p2->p_ucred->cr_uid) and
(p1->p_ucred->cr_uid == p2->p_ucred->cr_uid), respectively permitting
a subject process to influence the scheduling of a daemon if the subject
process has the same real uid or effective uid as the daemon's effective
uid. This removes a number of the warning cases identified by the
proc_to_proc iner-process authorization regression test.
o As these are new restrictions, we'll have to watch out carefully for
possible side effects on running code: they seem reasonable to me,
but it's possible this change might have to be backed out if problems
are experienced.
Reported by: src/tools/regression/security/proc_to_proc/testuid
Obtained from: TrustedBSD Project
by p_can(...P_CAN_SEE), rather than returning EACCES directly. This
brings the error code used here into line with similar arrangements
elsewhere, and prevents the leakage of pid usage information.
Reviewed by: jlemon
Obtained from: TrustedBSD Project
p_can(...P_CAN_SEE...) to getpgid(), getsid(), and setpgid(),
blocking these operations on processes that should not be visible
by the requesting process. Required to reduce information leakage
in MAC environments.
Obtained from: TrustedBSD Project
