From: Paul Moore <paul@paul-moore.com> To: Casey Schaufler <casey@schaufler-ca.com> Cc: Kees Cook <keescook@chromium.org>, casey.schaufler@intel.com, James Morris <jmorris@namei.org>, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-audit@redhat.com, john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp, Stephen Smalley <sds@tycho.nsa.gov>, linux-kernel@vger.kernel.org, Stephen Smalley <stephen.smalley.work@gmail.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, linux-api@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [PATCH v26 14/25] LSM: Specify which LSM to display Date: Fri, 21 May 2021 16:19:08 -0400 [thread overview] Message-ID: <CAHC9VhScDhmr2k5RpNhj1=6FpO_xPN1C6_qFqbXb6SWUbBiENA@mail.gmail.com> (raw) In-Reply-To: <c1ab101a-7ee3-6d20-c8b1-cff5bcdfe98c@schaufler-ca.com> On Mon, May 17, 2021 at 3:53 PM Casey Schaufler <casey@schaufler-ca.com> wrote: > On 5/14/2021 12:23 PM, Kees Cook wrote: > > On Thu, May 13, 2021 at 01:07:56PM -0700, Casey Schaufler wrote: > >> Create a new entry "interface_lsm" in the procfs attr directory for > >> controlling which LSM security information is displayed for a > >> process. A process can only read or write its own display value. > >> > >> The name of an active LSM that supplies hooks for > >> human readable data may be written to "interface_lsm" to set the > >> value. The name of the LSM currently in use can be read from > >> "interface_lsm". At this point there can only be one LSM capable > >> of display active. A helper function lsm_task_ilsm() is > >> provided to get the interface lsm slot for a task_struct. > >> > >> Setting the "interface_lsm" requires that all security modules using > >> setprocattr hooks allow the action. Each security module is > >> responsible for defining its policy. > >> > >> AppArmor hook provided by John Johansen <john.johansen@canonical.com> > >> SELinux hook provided by Stephen Smalley <stephen.smalley.work@gmail.com> > >> > >> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> > >> Cc: Kees Cook <keescook@chromium.org> > >> Cc: Stephen Smalley <stephen.smalley.work@gmail.com> > >> Cc: Paul Moore <paul@paul-moore.com> > >> Cc: John Johansen <john.johansen@canonical.com> > >> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > >> Cc: linux-api@vger.kernel.org > >> Cc: linux-doc@vger.kernel.org > >> --- > >> .../ABI/testing/procfs-attr-lsm_display | 22 +++ > >> Documentation/security/lsm.rst | 14 ++ > >> fs/proc/base.c | 1 + > >> include/linux/lsm_hooks.h | 17 ++ > >> security/apparmor/include/apparmor.h | 3 +- > >> security/apparmor/lsm.c | 32 ++++ > >> security/security.c | 166 ++++++++++++++++-- > >> security/selinux/hooks.c | 11 ++ > >> security/selinux/include/classmap.h | 2 +- > >> security/smack/smack_lsm.c | 7 + > >> 10 files changed, 256 insertions(+), 19 deletions(-) > >> create mode 100644 Documentation/ABI/testing/procfs-attr-lsm_display ... > >> @@ -2171,23 +2203,110 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name, > >> char **value) > >> { > >> struct security_hook_list *hp; > >> + int ilsm = lsm_task_ilsm(current); > >> + int slot = 0; > >> + > >> + if (!strcmp(name, "interface_lsm")) { > >> + /* > >> + * lsm_slot will be 0 if there are no displaying modules. > >> + */ > >> + if (lsm_slot == 0) > >> + return -EINVAL; > >> + > >> + /* > >> + * Only allow getting the current process' interface_lsm. > >> + * There are too few reasons to get another process' > >> + * interface_lsm and too many LSM policy issues. > >> + */ > >> + if (current != p) > >> + return -EINVAL; > > ... but context isn't established by just checking "current", as this > > file handle may have been given to another process. > > > > I suspect the security_get/setprocattr needs to gain a pointer to "file" > > so that the f_cred struct can be examined[1] (i.e. compare opener > > against reader/writer). > > > > [1] https://www.kernel.org/doc/html/latest/security/credentials.html#open-file-credentials > > It's not credentials being checked here. The check is whether the task that > would be affected is "current". Process A can't open /proc/B/attr/interface_lsm > with write access. The only process that can open it for write access is B. > If process B opens /proc/B/attr/interface_lsm for write access it could send > the file handle to process A, but process A can't write to the file because > (current != p) that is, (A != B). Agreed. Acked-by: Paul Moore <paul@paul-moore.com> -- paul moore www.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, linux-doc@vger.kernel.org, selinux@vger.kernel.org, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, James Morris <jmorris@namei.org>, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-audit@redhat.com, linux-api@vger.kernel.org, casey.schaufler@intel.com, Stephen Smalley <sds@tycho.nsa.gov> Subject: Re: [PATCH v26 14/25] LSM: Specify which LSM to display Date: Fri, 21 May 2021 16:19:08 -0400 [thread overview] Message-ID: <CAHC9VhScDhmr2k5RpNhj1=6FpO_xPN1C6_qFqbXb6SWUbBiENA@mail.gmail.com> (raw) In-Reply-To: <c1ab101a-7ee3-6d20-c8b1-cff5bcdfe98c@schaufler-ca.com> On Mon, May 17, 2021 at 3:53 PM Casey Schaufler <casey@schaufler-ca.com> wrote: > On 5/14/2021 12:23 PM, Kees Cook wrote: > > On Thu, May 13, 2021 at 01:07:56PM -0700, Casey Schaufler wrote: > >> Create a new entry "interface_lsm" in the procfs attr directory for > >> controlling which LSM security information is displayed for a > >> process. A process can only read or write its own display value. > >> > >> The name of an active LSM that supplies hooks for > >> human readable data may be written to "interface_lsm" to set the > >> value. The name of the LSM currently in use can be read from > >> "interface_lsm". At this point there can only be one LSM capable > >> of display active. A helper function lsm_task_ilsm() is > >> provided to get the interface lsm slot for a task_struct. > >> > >> Setting the "interface_lsm" requires that all security modules using > >> setprocattr hooks allow the action. Each security module is > >> responsible for defining its policy. > >> > >> AppArmor hook provided by John Johansen <john.johansen@canonical.com> > >> SELinux hook provided by Stephen Smalley <stephen.smalley.work@gmail.com> > >> > >> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> > >> Cc: Kees Cook <keescook@chromium.org> > >> Cc: Stephen Smalley <stephen.smalley.work@gmail.com> > >> Cc: Paul Moore <paul@paul-moore.com> > >> Cc: John Johansen <john.johansen@canonical.com> > >> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > >> Cc: linux-api@vger.kernel.org > >> Cc: linux-doc@vger.kernel.org > >> --- > >> .../ABI/testing/procfs-attr-lsm_display | 22 +++ > >> Documentation/security/lsm.rst | 14 ++ > >> fs/proc/base.c | 1 + > >> include/linux/lsm_hooks.h | 17 ++ > >> security/apparmor/include/apparmor.h | 3 +- > >> security/apparmor/lsm.c | 32 ++++ > >> security/security.c | 166 ++++++++++++++++-- > >> security/selinux/hooks.c | 11 ++ > >> security/selinux/include/classmap.h | 2 +- > >> security/smack/smack_lsm.c | 7 + > >> 10 files changed, 256 insertions(+), 19 deletions(-) > >> create mode 100644 Documentation/ABI/testing/procfs-attr-lsm_display ... > >> @@ -2171,23 +2203,110 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name, > >> char **value) > >> { > >> struct security_hook_list *hp; > >> + int ilsm = lsm_task_ilsm(current); > >> + int slot = 0; > >> + > >> + if (!strcmp(name, "interface_lsm")) { > >> + /* > >> + * lsm_slot will be 0 if there are no displaying modules. > >> + */ > >> + if (lsm_slot == 0) > >> + return -EINVAL; > >> + > >> + /* > >> + * Only allow getting the current process' interface_lsm. > >> + * There are too few reasons to get another process' > >> + * interface_lsm and too many LSM policy issues. > >> + */ > >> + if (current != p) > >> + return -EINVAL; > > ... but context isn't established by just checking "current", as this > > file handle may have been given to another process. > > > > I suspect the security_get/setprocattr needs to gain a pointer to "file" > > so that the f_cred struct can be examined[1] (i.e. compare opener > > against reader/writer). > > > > [1] https://www.kernel.org/doc/html/latest/security/credentials.html#open-file-credentials > > It's not credentials being checked here. The check is whether the task that > would be affected is "current". Process A can't open /proc/B/attr/interface_lsm > with write access. The only process that can open it for write access is B. > If process B opens /proc/B/attr/interface_lsm for write access it could send > the file handle to process A, but process A can't write to the file because > (current != p) that is, (A != B). Agreed. Acked-by: Paul Moore <paul@paul-moore.com> -- paul moore www.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:[~2021-05-21 20:19 UTC|newest] Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <20210513200807.15910-1-casey.ref@schaufler-ca.com> 2021-05-13 20:07 ` [PATCH v26 00/25] LSM: Module stacking for AppArmor Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-13 20:07 ` [PATCH v26 01/25] LSM: Infrastructure management of the sock security Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-13 20:07 ` [PATCH v26 02/25] LSM: Add the lsmblob data structure Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-22 8:39 ` Mickaël Salaün 2021-05-22 8:39 ` Mickaël Salaün 2021-05-25 23:52 ` Casey Schaufler 2021-05-25 23:52 ` Casey Schaufler 2021-05-26 9:53 ` Mickaël Salaün 2021-05-26 9:53 ` Mickaël Salaün 2021-05-13 20:07 ` [PATCH v26 03/25] LSM: provide lsm name and id slot mappings Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-14 19:00 ` Kees Cook 2021-05-14 19:00 ` Kees Cook 2021-05-21 20:18 ` Paul Moore 2021-05-21 20:18 ` Paul Moore 2021-05-13 20:07 ` [PATCH v26 04/25] IMA: avoid label collisions with stacked LSMs Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-14 19:00 ` Kees Cook 2021-05-14 19:00 ` Kees Cook 2021-05-13 20:07 ` [PATCH v26 05/25] LSM: Use lsmblob in security_audit_rule_match Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-13 20:07 ` [PATCH v26 06/25] LSM: Use lsmblob in security_kernel_act_as Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-13 20:07 ` [PATCH v26 07/25] LSM: Use lsmblob in security_secctx_to_secid Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-14 19:03 ` Kees Cook 2021-05-14 19:03 ` Kees Cook 2021-05-21 20:18 ` Paul Moore 2021-05-21 20:18 ` Paul Moore 2021-05-13 20:07 ` [PATCH v26 08/25] LSM: Use lsmblob in security_secid_to_secctx Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-14 19:05 ` Kees Cook 2021-05-14 19:05 ` Kees Cook 2021-05-21 20:18 ` Paul Moore 2021-05-21 20:18 ` Paul Moore 2021-05-13 20:07 ` [PATCH v26 09/25] LSM: Use lsmblob in security_ipc_getsecid Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-13 20:07 ` [PATCH v26 10/25] LSM: Use lsmblob in security_task_getsecid Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-13 20:07 ` [PATCH v26 11/25] LSM: Use lsmblob in security_inode_getsecid Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-13 20:07 ` [PATCH v26 12/25] LSM: Use lsmblob in security_cred_getsecid Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-13 20:07 ` [PATCH v26 13/25] IMA: Change internal interfaces to use lsmblobs Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-13 20:07 ` [PATCH v26 14/25] LSM: Specify which LSM to display Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-14 19:23 ` Kees Cook 2021-05-14 19:23 ` Kees Cook 2021-05-17 19:52 ` Casey Schaufler 2021-05-17 19:52 ` Casey Schaufler 2021-05-21 20:19 ` Paul Moore [this message] 2021-05-21 20:19 ` Paul Moore 2021-05-13 20:07 ` [PATCH v26 15/25] LSM: Ensure the correct LSM context releaser Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-21 20:19 ` Paul Moore 2021-05-21 20:19 ` Paul Moore 2021-05-13 20:07 ` [PATCH v26 16/25] LSM: Use lsmcontext in security_secid_to_secctx Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-13 20:07 ` [PATCH v26 17/25] LSM: Use lsmcontext in security_inode_getsecctx Casey Schaufler 2021-05-13 20:07 ` Casey Schaufler 2021-05-14 19:24 ` Kees Cook 2021-05-14 19:24 ` Kees Cook 2021-05-13 20:08 ` [PATCH v26 18/25] LSM: security_secid_to_secctx in netlink netfilter Casey Schaufler 2021-05-13 20:08 ` Casey Schaufler 2021-05-21 20:19 ` Paul Moore 2021-05-21 20:19 ` Paul Moore 2021-05-13 20:08 ` [PATCH v26 19/25] NET: Store LSM netlabel data in a lsmblob Casey Schaufler 2021-05-13 20:08 ` Casey Schaufler 2021-05-13 20:08 ` [PATCH v26 20/25] LSM: Verify LSM display sanity in binder Casey Schaufler 2021-05-13 20:08 ` Casey Schaufler 2021-05-13 20:08 ` [PATCH v26 21/25] audit: add support for non-syscall auxiliary records Casey Schaufler 2021-05-13 20:08 ` Casey Schaufler 2021-05-21 20:19 ` Paul Moore 2021-05-21 20:19 ` Paul Moore 2021-05-13 20:08 ` [PATCH v26 22/25] Audit: Add new record for multiple process LSM attributes Casey Schaufler 2021-05-13 20:08 ` Casey Schaufler 2021-05-21 20:19 ` Paul Moore 2021-05-21 20:19 ` Paul Moore 2021-05-21 21:26 ` Richard Guy Briggs 2021-05-21 21:26 ` Richard Guy Briggs 2021-05-21 22:05 ` Casey Schaufler 2021-05-21 22:05 ` Casey Schaufler 2021-05-22 2:20 ` Paul Moore 2021-05-22 2:20 ` Paul Moore 2021-05-22 12:58 ` Richard Guy Briggs 2021-05-22 12:58 ` Richard Guy Briggs 2021-05-23 2:00 ` Steve Grubb 2021-05-24 15:53 ` Casey Schaufler 2021-05-24 16:06 ` Steve Grubb 2021-05-25 16:26 ` Casey Schaufler 2021-05-25 16:26 ` Casey Schaufler 2021-05-25 17:28 ` Casey Schaufler 2021-05-25 17:28 ` Casey Schaufler 2021-05-25 18:23 ` Richard Guy Briggs 2021-05-25 18:23 ` Richard Guy Briggs 2021-05-25 19:06 ` Casey Schaufler 2021-05-25 19:06 ` Casey Schaufler 2021-05-25 20:08 ` Richard Guy Briggs 2021-05-25 20:08 ` Richard Guy Briggs 2021-05-25 22:46 ` Casey Schaufler 2021-05-25 22:46 ` Casey Schaufler 2021-05-13 20:08 ` [PATCH v26 23/25] Audit: Add a new record for multiple object " Casey Schaufler 2021-05-13 20:08 ` Casey Schaufler 2021-05-13 20:08 ` [PATCH v26 24/25] LSM: Add /proc attr entry for full LSM context Casey Schaufler 2021-05-13 20:08 ` Casey Schaufler 2021-05-13 20:08 ` [PATCH v26 25/25] AppArmor: Remove the exclusive flag Casey Schaufler 2021-05-13 20:08 ` Casey Schaufler
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