Re: [PATCH] [BZ905179] audit: omit check for uid and gid validity in audit rules and data

On Tue, Apr 09, 2013 at 02:39:32AM -0700, Eric W. Biederman wrote: > Andrew Morton <akpm(a)linux-foundation.org&gt; writes: > > On Wed, 20 Mar 2013 15:18:17 -0400 Richard Guy Briggs <rgb(a)redhat.com&gt;

> >> audit rule additions containing "-F auid!=4294967295" were failing with > >> EINVAL.> > The only case where this appears to make the least little bit of sense > is if the goal of the test is to test to see if an audit logloginuid > has been set at all. In which case depending on a test against > 4294967295 is bogus because you are depending on an intimate internal > kernel implementation detail. > > How about something like my untested patch below that add an explicit > operation to test if loginuid has been set? Sorry for the delay in testing this, I had another urgent bug and a belligerent test box... I like this approach better than mine now that I understand it. I've tested the patch below without any changes. It works as expected with my previous test case. I don't know if a Signed-off-by: is appropriate for me in this case, but I'll throw in a: Tested-by: Richard Guy Briggs <rbriggs(a)redhat.com&gt; and recommend a: Reported-By: Steve Grubb <sbrubb(a)redhat.com&gt;

> From: "Eric W. Biederman" <ebiederm(a)xmission.com&gt; > Date: Tue, 9 Apr 2013 02:22:10 -0700 > Subject: [PATCH] audit: Make testing for a valid loginuid explicit. > > audit rule additions containing "-F auid!=4294967295" were failing > with EINVAL. > > Apparently some userland audit rule sets want to know if loginuid uid > has been set and are using a test for auid != 4294967295 to determine > that. > > In practice that is a horrible way to ask if a value has been set, > because it relies on subtle implementation details and will break > every time the uid implementation in the kernel changes. > > So add a clean way to test if the audit loginuid has been set, and > silently convert the old idiom to the cleaner and more comprehensible > new idiom. > > Reported-By: Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > Signed-off-by: "Eric W. Biederman" <ebiederm(a)xmission.com&gt; > --- > > include/linux/audit.h | 5 +++++ > include/uapi/linux/audit.h | 1 + > kernel/auditfilter.c | 29 +++++++++++++++++++++++++++++ > kernel/auditsc.c | 5 ++++- > 4 files changed, 39 insertions(+), 1 deletions(-) > > diff --git a/include/linux/audit.h b/include/linux/audit.h > index a9fefe2..8a1ddde 100644 > --- a/include/linux/audit.h > +++ b/include/linux/audit.h > @@ -390,6 +390,11 @@ static inline void audit_ptrace(struct task_struct > *t) > > #define audit_signals 0 > #endif /* CONFIG_AUDITSYSCALL */ > > +static inline bool audit_loginuid_set(struct task_struct *tsk) > +{ > + return uid_valid(audit_get_loginuid(tsk)); > +} > + > > #ifdef CONFIG_AUDIT > /* These are defined in audit.c */ > > /* Public API */ > > diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h > index 9f096f1..9554a19 100644 > --- a/include/uapi/linux/audit.h > +++ b/include/uapi/linux/audit.h > @@ -246,6 +246,7 @@ > > #define AUDIT_OBJ_TYPE 21 > #define AUDIT_OBJ_LEV_LOW 22 > #define AUDIT_OBJ_LEV_HIGH 23 > > +#define AUDIT_LOGINUID_SET 24 > > /* These are ONLY useful when checking > > * at syscall exit time (AUDIT_AT_EXIT). */ > > diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c > index 540f986..6381d17 100644 > --- a/kernel/auditfilter.c > +++ b/kernel/auditfilter.c > @@ -349,6 +349,12 @@ static struct audit_entry *audit_rule_to_entry(struct > audit_rule *rule)> > if (f->op == Audit_bad) > > goto exit_free; > > + /* Support legacy tests for a valid loginuid */ > + if ((f->type == AUDIT_LOGINUID) && (f->val == 4294967295)) { > + f->type = AUDIT_LOGINUID_SET; > + f->val = 0; > + } > + > > switch(f->type) { > > default: > goto exit_free; > > @@ -377,6 +383,12 @@ static struct audit_entry *audit_rule_to_entry(struct > audit_rule *rule)> > if (!gid_valid(f->gid)) > > goto exit_free; > > break; > > + case AUDIT_LOGINUID_SET: > + if ((f->op != Audit_not_equal) && (f->op != Audit_equal)) > + goto exit_free; > + if ((f->val != 0) && (f->val != 1)) > + goto exit_free; > + break; > > case AUDIT_PID: > case AUDIT_PERS: > > case AUDIT_MSGTYPE: > @@ -459,6 +471,13 @@ static struct audit_entry *audit_data_to_entry(struct > audit_rule_data *data,> > f->gid = INVALID_GID; > f->lsm_str = NULL; > f->lsm_rule = NULL; > > + > + /* Support legacy tests for a valid loginuid */ > + if ((f->type == AUDIT_LOGINUID) && (f->val == 4294967295)) { > + f->type = AUDIT_LOGINUID_SET; > + f->val = 0; > + } > + > > switch(f->type) { > case AUDIT_UID: > > case AUDIT_EUID: > @@ -487,6 +506,12 @@ static struct audit_entry *audit_data_to_entry(struct > audit_rule_data *data,> > if (!gid_valid(f->gid)) > > goto exit_free; > > break; > > + case AUDIT_LOGINUID_SET: > + if ((f->op != Audit_not_equal) && (f->op != Audit_equal)) > + goto exit_free; > + if ((f->val != 0) && (f->val != 1)) > + goto exit_free; > + break; > > case AUDIT_PID: > case AUDIT_PERS: > > case AUDIT_MSGTYPE: > @@ -1380,6 +1405,10 @@ static int audit_filter_user_rules(struct > audit_krule *rule,> > result = audit_uid_comparator(audit_get_loginuid(current), > > f->op, f->uid); > > break; > > + case AUDIT_LOGINUID_SET: > + result = audit_comparator(audit_loginuid_set(current), > + f->op, f->val); > + break; > > case AUDIT_SUBJ_USER: > case AUDIT_SUBJ_ROLE: > > case AUDIT_SUBJ_TYPE: > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > index 3a11d34..27d0a50 100644 > --- a/kernel/auditsc.c > +++ b/kernel/auditsc.c > @@ -750,6 +750,9 @@ static int audit_filter_rules(struct task_struct *tsk, > > if (ctx) > > result = audit_uid_comparator(tsk->loginuid, f->op,

> > break; > > + case AUDIT_LOGINUID_SET: > + result = audit_comparator(audit_loginuid_set(tsk), f->op,

> + break; > > case AUDIT_SUBJ_USER: > case AUDIT_SUBJ_ROLE: > > case AUDIT_SUBJ_TYPE: > @@ -2317,7 +2320,7 @@ int audit_set_loginuid(kuid_t loginuid) > > unsigned int sessionid; > > #ifdef CONFIG_AUDIT_LOGINUID_IMMUTABLE > > - if (uid_valid(task->loginuid)) > + if (audit_loginuid_set(task)) > > return -EPERM; > > #else /* CONFIG_AUDIT_LOGINUID_IMMUTABLE */ > > if (!capable(CAP_AUDIT_CONTROL)) - RGB -- Richard Guy Briggs <rbriggs(a)redhat.com&gt; Senior Software Engineer AMER ENG Base Operating Systems Remote, Canada, Ottawa Voice: 1.647.777.2635 Internal: (81) 32635 -- Linux-audit mailing list Linux-audit(a)redhat.com https://www.redhat.com/mailman/listinfo/linux-audit