From: Paul Moore <paul@paul-moore.com> To: Casey Schaufler <casey@schaufler-ca.com> Cc: casey.schaufler@intel.com, jmorris@namei.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-audit@redhat.com, keescook@chromium.org, john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp, stephen.smalley.work@gmail.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v33 26/29] Audit: Add record for multiple task security contexts Date: Tue, 15 Mar 2022 19:47:42 -0400 [thread overview] Message-ID: <CAHC9VhSYr3nC87jk+cPzvVLgYZO9p9vaM7n+jvGEF60RaNJw7A@mail.gmail.com> (raw) In-Reply-To: <20220310234632.16194-27-casey@schaufler-ca.com> On Thu, Mar 10, 2022 at 6:59 PM Casey Schaufler <casey@schaufler-ca.com> wrote: > > Create a new audit record AUDIT_MAC_TASK_CONTEXTS. > An example of the MAC_TASK_CONTEXTS (1420) record is: > > type=MAC_TASK_CONTEXTS[1420] > msg=audit(1600880931.832:113) > subj_apparmor=unconfined > subj_smack=_ > > When an audit event includes a AUDIT_MAC_TASK_CONTEXTS record > the "subj=" field in other records in the event will be "subj=?". > An AUDIT_MAC_TASK_CONTEXTS record is supplied when the system has > multiple security modules that may make access decisions based > on a subject security context. > > Functions are created to manage the skb list in the audit_buffer. > > Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> > --- > include/uapi/linux/audit.h | 1 + > kernel/audit.c | 104 ++++++++++++++++++++++++++++++++----- > 2 files changed, 93 insertions(+), 12 deletions(-) > > diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h > index 8eda133ca4c1..af0aaccfaf57 100644 > --- a/include/uapi/linux/audit.h > +++ b/include/uapi/linux/audit.h > @@ -143,6 +143,7 @@ > #define AUDIT_MAC_UNLBL_STCDEL 1417 /* NetLabel: del a static label */ > #define AUDIT_MAC_CALIPSO_ADD 1418 /* NetLabel: add CALIPSO DOI entry */ > #define AUDIT_MAC_CALIPSO_DEL 1419 /* NetLabel: del CALIPSO DOI entry */ > +#define AUDIT_MAC_TASK_CONTEXTS 1420 /* Multiple LSM task contexts */ > > #define AUDIT_FIRST_KERN_ANOM_MSG 1700 > #define AUDIT_LAST_KERN_ANOM_MSG 1799 > diff --git a/kernel/audit.c b/kernel/audit.c > index 4713e66a12af..ad825af203cf 100644 > --- a/kernel/audit.c > +++ b/kernel/audit.c > @@ -2147,8 +2147,65 @@ void audit_log_key(struct audit_buffer *ab, char *key) > audit_log_format(ab, "(null)"); > } > > +/* > + * A brief note on aux record management. > + * > + * Aux records are allocated and added to the skb list of > + * the "main" record. The ab->skb is reset to point to the > + * aux record on its creation. When the aux record in complete ^^ "is" > + * ab->skb has to be reset to point to the "main" record. > + * This allows the audit_log_ functions to be ignorant of > + * which kind of record it is logging to. It also avoids adding > + * special data for aux records. > + */ It might be good to move the above comment into the audit_buffer_aux_new() comment header (below) so it does not get misplaced. > +/** > + * audit_buffer_aux_new - Add an aux record buffer to the skb list > + * @ab: audit_buffer > + * @type: message type > + * > + * On success ab->skb will point to the new aux record. > + * Returns 0 on success, -ENOMEM should allocation fail. > + */ > +static int audit_buffer_aux_new(struct audit_buffer *ab, int type) ... > @@ -2157,16 +2214,44 @@ int audit_log_task_context(struct audit_buffer *ab) > if (!lsmblob_is_set(&blob)) > return 0; > > - error = security_secid_to_secctx(&blob, &context, LSMBLOB_FIRST); > + if (!lsm_multiple_contexts()) { > + error = security_secid_to_secctx(&blob, &context, > + LSMBLOB_FIRST); > + if (error) { > + if (error != -EINVAL) > + goto error_path; > + return 0; > + } > > - if (error) { > - if (error != -EINVAL) > + audit_log_format(ab, " subj=%s", context.context); > + security_release_secctx(&context); > + } else { > + /* Multiple LSMs provide contexts. Include an aux record. */ > + audit_log_format(ab, " subj=?"); > + error = audit_buffer_aux_new(ab, AUDIT_MAC_TASK_CONTEXTS); > + if (error) > goto error_path; > - return 0; > + for (i = 0; i < LSMBLOB_ENTRIES; i++) { > + if (blob.secid[i] == 0) > + continue; > + error = security_secid_to_secctx(&blob, &context, i); > + if (error) { > + if (error != -EINVAL) > + audit_panic("error in audit_log_task_context"); > + audit_log_format(ab, "%ssubj_%s=?", > + i ? " " : "", > + lsm_slot_to_name(i)); I wonder if it might be better to record the "subj_smack=?" field before checking @error and potentially calling audit_panic(). In practice it likely shouldn't matter, I feel better if we at least record the subject information before we call the wildcard that is audit_panic(). > + } else { > + audit_log_format(ab, "%ssubj_%s=%s", > + i ? " " : "", > + lsm_slot_to_name(i), > + context.context); > + security_release_secctx(&context); > + } > + } > + audit_buffer_aux_end(ab); > } > > - audit_log_format(ab, " subj=%s", context.context); > - security_release_secctx(&context); > return 0; > > error_path: > @@ -2382,13 +2467,8 @@ int audit_signal_info(int sig, struct task_struct *t) > } > > /** > - * __audit_log_end - end one audit record > + * __audit_log_end - send one audit record If we want to be very nit-picky here, "end" is more correct than "send". First, audit_log_end() doesn't actually send the record, it just queues the record for the kauditd_thread which then attempts to send it. Second, there is no guarantee that the record will actually be sent at this point, although it would be nice if that were true :) > * @skb: the buffer to send > - * > - * We can not do a netlink send inside an irq context because it blocks (last > - * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a > - * queue and a kthread is scheduled to remove them from the queue outside the > - * irq context. May be called in any context. > */ This should probably be moved to patch 25/29 as it has more to do with the __audit_log_end() introduction than this patch. -- paul-moore.com
WARNING: multiple messages have this Message-ID (diff)
From: Paul Moore <paul@paul-moore.com> To: Casey Schaufler <casey@schaufler-ca.com> Cc: john.johansen@canonical.com, selinux@vger.kernel.org, jmorris@namei.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-audit@redhat.com, casey.schaufler@intel.com Subject: Re: [PATCH v33 26/29] Audit: Add record for multiple task security contexts Date: Tue, 15 Mar 2022 19:47:42 -0400 [thread overview] Message-ID: <CAHC9VhSYr3nC87jk+cPzvVLgYZO9p9vaM7n+jvGEF60RaNJw7A@mail.gmail.com> (raw) In-Reply-To: <20220310234632.16194-27-casey@schaufler-ca.com> On Thu, Mar 10, 2022 at 6:59 PM Casey Schaufler <casey@schaufler-ca.com> wrote: > > Create a new audit record AUDIT_MAC_TASK_CONTEXTS. > An example of the MAC_TASK_CONTEXTS (1420) record is: > > type=MAC_TASK_CONTEXTS[1420] > msg=audit(1600880931.832:113) > subj_apparmor=unconfined > subj_smack=_ > > When an audit event includes a AUDIT_MAC_TASK_CONTEXTS record > the "subj=" field in other records in the event will be "subj=?". > An AUDIT_MAC_TASK_CONTEXTS record is supplied when the system has > multiple security modules that may make access decisions based > on a subject security context. > > Functions are created to manage the skb list in the audit_buffer. > > Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> > --- > include/uapi/linux/audit.h | 1 + > kernel/audit.c | 104 ++++++++++++++++++++++++++++++++----- > 2 files changed, 93 insertions(+), 12 deletions(-) > > diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h > index 8eda133ca4c1..af0aaccfaf57 100644 > --- a/include/uapi/linux/audit.h > +++ b/include/uapi/linux/audit.h > @@ -143,6 +143,7 @@ > #define AUDIT_MAC_UNLBL_STCDEL 1417 /* NetLabel: del a static label */ > #define AUDIT_MAC_CALIPSO_ADD 1418 /* NetLabel: add CALIPSO DOI entry */ > #define AUDIT_MAC_CALIPSO_DEL 1419 /* NetLabel: del CALIPSO DOI entry */ > +#define AUDIT_MAC_TASK_CONTEXTS 1420 /* Multiple LSM task contexts */ > > #define AUDIT_FIRST_KERN_ANOM_MSG 1700 > #define AUDIT_LAST_KERN_ANOM_MSG 1799 > diff --git a/kernel/audit.c b/kernel/audit.c > index 4713e66a12af..ad825af203cf 100644 > --- a/kernel/audit.c > +++ b/kernel/audit.c > @@ -2147,8 +2147,65 @@ void audit_log_key(struct audit_buffer *ab, char *key) > audit_log_format(ab, "(null)"); > } > > +/* > + * A brief note on aux record management. > + * > + * Aux records are allocated and added to the skb list of > + * the "main" record. The ab->skb is reset to point to the > + * aux record on its creation. When the aux record in complete ^^ "is" > + * ab->skb has to be reset to point to the "main" record. > + * This allows the audit_log_ functions to be ignorant of > + * which kind of record it is logging to. It also avoids adding > + * special data for aux records. > + */ It might be good to move the above comment into the audit_buffer_aux_new() comment header (below) so it does not get misplaced. > +/** > + * audit_buffer_aux_new - Add an aux record buffer to the skb list > + * @ab: audit_buffer > + * @type: message type > + * > + * On success ab->skb will point to the new aux record. > + * Returns 0 on success, -ENOMEM should allocation fail. > + */ > +static int audit_buffer_aux_new(struct audit_buffer *ab, int type) ... > @@ -2157,16 +2214,44 @@ int audit_log_task_context(struct audit_buffer *ab) > if (!lsmblob_is_set(&blob)) > return 0; > > - error = security_secid_to_secctx(&blob, &context, LSMBLOB_FIRST); > + if (!lsm_multiple_contexts()) { > + error = security_secid_to_secctx(&blob, &context, > + LSMBLOB_FIRST); > + if (error) { > + if (error != -EINVAL) > + goto error_path; > + return 0; > + } > > - if (error) { > - if (error != -EINVAL) > + audit_log_format(ab, " subj=%s", context.context); > + security_release_secctx(&context); > + } else { > + /* Multiple LSMs provide contexts. Include an aux record. */ > + audit_log_format(ab, " subj=?"); > + error = audit_buffer_aux_new(ab, AUDIT_MAC_TASK_CONTEXTS); > + if (error) > goto error_path; > - return 0; > + for (i = 0; i < LSMBLOB_ENTRIES; i++) { > + if (blob.secid[i] == 0) > + continue; > + error = security_secid_to_secctx(&blob, &context, i); > + if (error) { > + if (error != -EINVAL) > + audit_panic("error in audit_log_task_context"); > + audit_log_format(ab, "%ssubj_%s=?", > + i ? " " : "", > + lsm_slot_to_name(i)); I wonder if it might be better to record the "subj_smack=?" field before checking @error and potentially calling audit_panic(). In practice it likely shouldn't matter, I feel better if we at least record the subject information before we call the wildcard that is audit_panic(). > + } else { > + audit_log_format(ab, "%ssubj_%s=%s", > + i ? " " : "", > + lsm_slot_to_name(i), > + context.context); > + security_release_secctx(&context); > + } > + } > + audit_buffer_aux_end(ab); > } > > - audit_log_format(ab, " subj=%s", context.context); > - security_release_secctx(&context); > return 0; > > error_path: > @@ -2382,13 +2467,8 @@ int audit_signal_info(int sig, struct task_struct *t) > } > > /** > - * __audit_log_end - end one audit record > + * __audit_log_end - send one audit record If we want to be very nit-picky here, "end" is more correct than "send". First, audit_log_end() doesn't actually send the record, it just queues the record for the kauditd_thread which then attempts to send it. Second, there is no guarantee that the record will actually be sent at this point, although it would be nice if that were true :) > * @skb: the buffer to send > - * > - * We can not do a netlink send inside an irq context because it blocks (last > - * arg, flags, is not set to MSG_DONTWAIT), so the audit buffer is placed on a > - * queue and a kthread is scheduled to remove them from the queue outside the > - * irq context. May be called in any context. > */ This should probably be moved to patch 25/29 as it has more to do with the __audit_log_end() introduction than this patch. -- paul-moore.com -- Linux-audit mailing list Linux-audit@redhat.com https://listman.redhat.com/mailman/listinfo/linux-audit
next prev parent reply other threads:[~2022-03-15 23:48 UTC|newest] Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <20220310234632.16194-1-casey.ref@schaufler-ca.com> 2022-03-10 23:46 ` [PATCH v33 00/29] LSM: Module stacking for AppArmor Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 01/29] integrity: disassociate ima_filter_rule from security_audit_rule Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-11 10:48 ` kernel test robot 2022-03-11 10:48 ` kernel test robot 2022-03-10 23:46 ` [PATCH v33 02/29] LSM: Infrastructure management of the sock security Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 03/29] LSM: Add the lsmblob data structure Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 04/29] LSM: provide lsm name and id slot mappings Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 05/29] IMA: avoid label collisions with stacked LSMs Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 06/29] LSM: Use lsmblob in security_audit_rule_match Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 07/29] LSM: Use lsmblob in security_kernel_act_as Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 08/29] LSM: Use lsmblob in security_secctx_to_secid Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 09/29] LSM: Use lsmblob in security_secid_to_secctx Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 10/29] LSM: Use lsmblob in security_ipc_getsecid Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 11/29] LSM: Use lsmblob in security_current_getsecid Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 12/29] LSM: Use lsmblob in security_inode_getsecid Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 13/29] LSM: Use lsmblob in security_cred_getsecid Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-11 7:52 ` kernel test robot 2022-03-11 7:52 ` kernel test robot 2022-03-11 9:16 ` kernel test robot 2022-03-11 9:16 ` kernel test robot 2022-03-12 4:50 ` kernel test robot 2022-03-12 4:50 ` kernel test robot 2022-03-10 23:46 ` [PATCH v33 14/29] LSM: Specify which LSM to display Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 15/29] LSM: Ensure the correct LSM context releaser Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 16/29] LSM: Use lsmcontext in security_secid_to_secctx Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 17/29] LSM: Use lsmcontext in security_inode_getsecctx Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 18/29] LSM: security_secid_to_secctx in netlink netfilter Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 19/29] NET: Store LSM netlabel data in a lsmblob Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 20/29] binder: Pass LSM identifier for confirmation Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 21/29] LSM: Extend security_secid_to_secctx to include module selection Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 22/29] Audit: Keep multiple LSM data in audit_names Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 23/29] Audit: Create audit_stamp structure Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 24/29] LSM: Add a function to report multiple LSMs Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 25/29] Audit: Allow multiple records in an audit_buffer Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-15 23:47 ` Paul Moore 2022-03-15 23:47 ` Paul Moore 2022-03-16 0:06 ` Casey Schaufler 2022-03-16 0:06 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 26/29] Audit: Add record for multiple task security contexts Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-15 23:47 ` Paul Moore [this message] 2022-03-15 23:47 ` Paul Moore 2022-03-16 0:17 ` Casey Schaufler 2022-03-16 0:17 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 27/29] Audit: Add record for multiple object " Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-15 23:47 ` Paul Moore 2022-03-15 23:47 ` Paul Moore 2022-03-16 0:23 ` Casey Schaufler 2022-03-16 0:23 ` Casey Schaufler 2022-03-16 1:08 ` Paul Moore 2022-03-16 1:08 ` Paul Moore 2022-03-10 23:46 ` [PATCH v33 28/29] LSM: Add /proc attr entry for full LSM context Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler 2022-03-10 23:46 ` [PATCH v33 29/29] AppArmor: Remove the exclusive flag Casey Schaufler 2022-03-10 23:46 ` Casey Schaufler
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