[PATCH 2/2] audit: restore AUDIT_LOGINUID unset ABI
Paul Moore
pmoore at redhat.com
Fri Dec 12 16:39:06 UTC 2014
On Friday, December 12, 2014 12:20:16 AM Richard Guy Briggs wrote:
> A regression was caused by commit 780a7654cee8:
> audit: Make testing for a valid loginuid explicit.
> (which in turn attempted to fix a regression caused by e1760bd)
>
> When audit_krule_to_data() fills in the rules to get a listing, there was a
> missing clause to convert back from AUDIT_LOGINUID_SET to AUDIT_LOGINUID.
>
> This broke userspace by not returning the same information that was sent and
> expected.
>
> The rule:
> auditctl -a exit,never -F auid=-1
> gives:
> auditctl -l
> LIST_RULES: exit,never f24=0 syscall=all
> when it should give:
> LIST_RULES: exit,never auid=-1 (0xffffffff) syscall=all
>
> Tag it so that it is reported the same way it was set.
>
> Cc: stable at vger.kernel.org # v3.10-rc1+
> Signed-off-by: Richard Guy Briggs <rgb at redhat.com>
> ---
> include/linux/audit.h | 3 +++
> kernel/auditfilter.c | 10 +++++++++-
> 2 files changed, 12 insertions(+), 1 deletions(-)
>
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index eefc39a..d905832 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -63,6 +63,9 @@ struct audit_krule {
> u64 prio;
> };
>
> +/* Flag to indicate legacy AUDIT_LOGINUID unset usage */
> +#define AUDIT_LOGINUID_LEGACY 0x80000000
> +
> struct audit_field {
> u32 type;
> union {
> diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> index fb4d2df..ea62c7b 100644
> --- a/kernel/auditfilter.c
> +++ b/kernel/auditfilter.c
> @@ -441,6 +441,7 @@ static struct audit_entry *audit_data_to_entry(struct
> audit_rule_data *data, if ((f->type == AUDIT_LOGINUID) && (f->val ==
> AUDIT_UID_UNSET)) { f->type = AUDIT_LOGINUID_SET;
> f->val = 0;
> + entry->rule.flags |= AUDIT_LOGINUID_LEGACY;
> }
>
> if ((f->type == AUDIT_PID) || (f->type == AUDIT_PPID)) {
> @@ -592,7 +593,7 @@ static struct audit_rule_data
> *audit_krule_to_data(struct audit_krule *krule) return NULL;
> memset(data, 0, sizeof(*data));
>
> - data->flags = krule->flags | krule->listnr;
> + data->flags = (krule->flags & ~AUDIT_LOGINUID_LEGACY) | krule->listnr;
Argh! I missed that the audit_krule->flags end up in audit_rule_data->flags.
Bummer.
Some thoughts:
* Your 1/2 patch saved 32-bits in audit_krule, what are your thoughts on
adding a new 32-bit bitmap, say "private", which could be used internally to
track things like this? I'm not a big fan of overloading parts of the public
API for use by internal mechanisms, it almost always gets messy.
* Also, why is there both an audit_krule->flags and audit_krule->listnr field?
With the exception of the AUDIT_FILTER_PREPEND bit are they always going to be
the same? I wonder if some more cleanup could be done here ...
> data->action = krule->action;
> data->field_count = krule->field_count;
> bufp = data->buf;
> @@ -629,6 +630,13 @@ static struct audit_rule_data
> *audit_krule_to_data(struct audit_krule *krule) data->buflen +=
> data->values[i] =
> audit_pack_string(&bufp, krule->filterkey);
> break;
> + case AUDIT_LOGINUID_SET:
> + if (krule->flags & AUDIT_LOGINUID_LEGACY && !f->val) {
> + data->fields[i] = AUDIT_LOGINUID;
> + data->values[i] = AUDIT_UID_UNSET;
> + break;
> + }
> + /* fallthrough if set */
> default:
> data->values[i] = f->val;
> }
--
paul moore
security and virtualization @ redhat
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