Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754130AbYKJOyB (ORCPT ); Mon, 10 Nov 2008 09:54:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752259AbYKJOxw (ORCPT ); Mon, 10 Nov 2008 09:53:52 -0500 Received: from e34.co.us.ibm.com ([32.97.110.152]:47465 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752109AbYKJOxv (ORCPT ); Mon, 10 Nov 2008 09:53:51 -0500 Date: Mon, 10 Nov 2008 08:53:34 -0600 From: "Serge E. Hallyn" To: Eric Paris Cc: linux-kernel@vger.kernel.org, linux-audit@redhat.com, sgrubb@redhat.com, morgan@kernel.org, viro@ZenIV.linux.org.uk Subject: Re: [PATCH -v3 4/5] AUDIT: collect info when execve results in caps in pE Message-ID: <20081110145334.GC11561@us.ibm.com> References: <20081107151355.9977.47852.stgit@paris.rdu.redhat.com> <20081107151411.9977.24865.stgit@paris.rdu.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081107151411.9977.24865.stgit@paris.rdu.redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9904 Lines: 237 Quoting Eric Paris (eparis@redhat.com): > Any time fcaps or a setuid app under SECURE_NOROOT is used to result in a > non-zero pE we will crate a new audit record which contains the entire set > of known information about the executable in question, fP, fI, fE, fversion > and includes the process's pE, pI, pP. Before and after the bprm capability > are applied. This record type will only be emitted from execve syscalls. > > an example of making ping use fcaps instead of setuid: > > setcap "cat_net_raw+pe" /bin/ping > > type=SYSCALL msg=audit(1225742021.015:236): arch=c000003e syscall=59 success=yes exit=0 a0=1457f30 a1=14606b0 a2=1463940 a3=321b770a70 items=2 ppid=2929 pid=2963 auid=0 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 tty=pts0 ses=3 comm="ping" exe="/bin/ping" subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null) > type=UNKNOWN[1321] msg=audit(1225742021.015:236): fver=2 fp=0000000000002000 fi=0000000000000000 fe=1 old_pp=0000000000000000 old_pi=0000000000000000 old_pe=0000000000000000 new_pp=0000000000002000 new_pi=0000000000000000 new_pe=0000000000002000 > type=EXECVE msg=audit(1225742021.015:236): argc=2 a0="ping" a1="127.0.0.1" > type=CWD msg=audit(1225742021.015:236): cwd="/home/test" > type=PATH msg=audit(1225742021.015:236): item=0 name="/bin/ping" inode=49256 dev=fd:00 mode=0100755 ouid=0 ogid=0 rdev=00:00 obj=system_u:object_r:ping_exec_t:s0 cap_fp=0000000000002000 cap_fe=1 cap_fver=2 > type=PATH msg=audit(1225742021.015:236): item=1 name=(null) inode=507915 dev=fd:00 mode=0100755 ouid=0 ogid=0 rdev=00:00 obj=system_u:object_r:ld_so_t:s0 > > Signed-off-by: Eric Paris Acked-by: Serge Hallyn thanks -serge > --- > > include/linux/audit.h | 26 +++++++++++++++++++ > kernel/auditsc.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++ > security/commoncap.c | 23 ++++++++++++++++- > 3 files changed, 116 insertions(+), 1 deletions(-) > > diff --git a/include/linux/audit.h b/include/linux/audit.h > index 6272a39..8cfb9fe 100644 > --- a/include/linux/audit.h > +++ b/include/linux/audit.h > @@ -99,6 +99,7 @@ > #define AUDIT_OBJ_PID 1318 /* ptrace target */ > #define AUDIT_TTY 1319 /* Input on an administrative TTY */ > #define AUDIT_EOE 1320 /* End of multi-record event */ > +#define AUDIT_BPRM_FCAPS 1321 /* Information about fcaps increasing perms */ > > #define AUDIT_AVC 1400 /* SE Linux avc denial or grant */ > #define AUDIT_SELINUX_ERR 1401 /* Internal SE Linux Errors */ > @@ -452,6 +453,7 @@ extern int __audit_mq_timedsend(mqd_t mqdes, size_t msg_len, unsigned int msg_pr > extern int __audit_mq_timedreceive(mqd_t mqdes, size_t msg_len, unsigned int __user *u_msg_prio, const struct timespec __user *u_abs_timeout); > extern int __audit_mq_notify(mqd_t mqdes, const struct sigevent __user *u_notification); > extern int __audit_mq_getsetattr(mqd_t mqdes, struct mq_attr *mqstat); > +extern void __audit_log_bprm_fcaps(struct linux_binprm *bprm, kernel_cap_t *pP, kernel_cap_t *pE); > > static inline int audit_ipc_obj(struct kern_ipc_perm *ipcp) > { > @@ -501,6 +503,29 @@ static inline int audit_mq_getsetattr(mqd_t mqdes, struct mq_attr *mqstat) > return __audit_mq_getsetattr(mqdes, mqstat); > return 0; > } > + > +/* > + * ieieeeeee, an audit function without a return code! > + * > + * This function might fail! I decided that it didn't matter. We are too late > + * to fail the syscall and the information isn't REQUIRED for any purpose. It's > + * just nice to have. We should be able to look at past audit logs to figure > + * out this process's current cap set along with the fcaps from the PATH record > + * and use that to come up with the final set. Yeah, its ugly, but all the info > + * is still in the audit log. So I'm not going to bother mentioning we failed > + * if we couldn't allocate memory. > + * > + * If someone changes their mind they could create the aux record earlier and > + * then search here and use that earlier allocation. But I don't wanna. > + * > + * -Eric > + */ > +static inline void audit_log_bprm_fcaps(struct linux_binprm *bprm, kernel_cap_t *pP, kernel_cap_t *pE) > +{ > + if (unlikely(!audit_dummy_context())) > + __audit_log_bprm_fcaps(bprm, pP, pE); > +} > + > extern int audit_n_rules; > extern int audit_signals; > #else > @@ -532,6 +557,7 @@ extern int audit_signals; > #define audit_mq_timedreceive(d,l,p,t) ({ 0; }) > #define audit_mq_notify(d,n) ({ 0; }) > #define audit_mq_getsetattr(d,s) ({ 0; }) > +#define audit_log_bprm_fcaps(b, p, e) do { ; } while (0) > #define audit_ptrace(t) ((void)0) > #define audit_n_rules 0 > #define audit_signals 0 > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > index f87f31a..b8b5a2a 100644 > --- a/kernel/auditsc.c > +++ b/kernel/auditsc.c > @@ -196,6 +196,14 @@ struct audit_aux_data_pids { > int pid_count; > }; > > +struct audit_aux_data_bprm_fcaps { > + struct audit_aux_data d; > + struct audit_cap_data fcap; > + unsigned int fcap_ver; > + struct audit_cap_data old_pcap; > + struct audit_cap_data new_pcap; > +}; > + > struct audit_tree_refs { > struct audit_tree_refs *next; > struct audit_chunk *c[31]; > @@ -1375,6 +1383,20 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts > audit_log_format(ab, "fd0=%d fd1=%d", axs->fd[0], axs->fd[1]); > break; } > > + case AUDIT_BPRM_FCAPS: { > + struct audit_aux_data_bprm_fcaps *axs = (void *)aux; > + audit_log_format(ab, "fver=%x", axs->fcap_ver); > + audit_log_cap(ab, "fp", &axs->fcap.permitted); > + audit_log_cap(ab, "fi", &axs->fcap.inheritable); > + audit_log_format(ab, " fe=%d", axs->fcap.fE); > + audit_log_cap(ab, "old_pp", &axs->old_pcap.permitted); > + audit_log_cap(ab, "old_pi", &axs->old_pcap.inheritable); > + audit_log_cap(ab, "old_pe", &axs->old_pcap.effective); > + audit_log_cap(ab, "new_pp", &axs->new_pcap.permitted); > + audit_log_cap(ab, "new_pi", &axs->new_pcap.inheritable); > + audit_log_cap(ab, "new_pe", &axs->new_pcap.effective); > + break; } > + > } > audit_log_end(ab); > } > @@ -2502,6 +2524,52 @@ int __audit_signal_info(int sig, struct task_struct *t) > } > > /** > + * __audit_log_bprm_fcaps - store information about a loading bprm and relevant fcaps > + * @bprm pointer to the bprm being processed > + * @caps the caps read from the disk > + * > + * Simply check if the proc already has the caps given by the file and if not > + * store the priv escalation info for later auditing at the end of the syscall > + * > + * this can fail and we don't care. See the note in audit.h for > + * audit_log_bprm_fcaps() for my explaination.... > + * > + * -Eric > + */ > +void __audit_log_bprm_fcaps(struct linux_binprm *bprm, kernel_cap_t *pP, kernel_cap_t *pE) > +{ > + struct audit_aux_data_bprm_fcaps *ax; > + struct audit_context *context = current->audit_context; > + struct cpu_vfs_cap_data vcaps; > + struct dentry *dentry; > + > + ax = kmalloc(sizeof(*ax), GFP_KERNEL); > + if (!ax) > + return; > + > + ax->d.type = AUDIT_BPRM_FCAPS; > + ax->d.next = context->aux; > + context->aux = (void *)ax; > + > + dentry = dget(bprm->file->f_dentry); > + get_vfs_caps_from_disk(dentry, &vcaps); > + dput(dentry); > + > + ax->fcap.permitted = vcaps.permitted; > + ax->fcap.inheritable = vcaps.inheritable; > + ax->fcap.fE = !!(vcaps.magic_etc & VFS_CAP_FLAGS_EFFECTIVE); > + ax->fcap_ver = (vcaps.magic_etc & VFS_CAP_REVISION_MASK) >> VFS_CAP_REVISION_SHIFT; > + > + ax->old_pcap.permitted = *pP; > + ax->old_pcap.inheritable = current->cap_inheritable; > + ax->old_pcap.effective = *pE; > + > + ax->new_pcap.permitted = current->cap_permitted; > + ax->new_pcap.inheritable = current->cap_inheritable; > + ax->new_pcap.effective = current->cap_effective; > +} > + > +/** > * audit_core_dumps - record information about processes that end abnormally > * @signr: signal value > * > diff --git a/security/commoncap.c b/security/commoncap.c > index 8bb95ed..0b88160 100644 > --- a/security/commoncap.c > +++ b/security/commoncap.c > @@ -8,6 +8,7 @@ > */ > > #include > +#include > #include > #include > #include > @@ -373,6 +374,9 @@ int cap_bprm_set_security (struct linux_binprm *bprm) > > void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) > { > + kernel_cap_t pP = current->cap_permitted; > + kernel_cap_t pE = current->cap_effective; > + > if (bprm->e_uid != current->uid || bprm->e_gid != current->gid || > !cap_issubset(bprm->cap_post_exec_permitted, > current->cap_permitted)) { > @@ -406,7 +410,24 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe) > cap_clear(current->cap_effective); > } > > - /* AUD: Audit candidate if current->cap_effective is set */ > + /* > + * Audit candidate if current->cap_effective is set > + * > + * We do not bother to audit if 3 things are true: > + * 1) cap_effective has all caps > + * 2) we are root > + * 3) root is supposed to have all caps (SECURE_NOROOT) > + * Since this is just a normal root execing a process. > + * > + * Number 1 above might fail if you don't have a full bset, but I think > + * that is interesting information to audit. > + */ > + if (!cap_isclear(current->cap_effective)) { > + if (!cap_issubset(CAP_FULL_SET, current->cap_effective) || > + (bprm->e_uid != 0) || (current->uid != 0) || > + issecure(SECURE_NOROOT)) > + audit_log_bprm_fcaps(bprm, &pP, &pE); > + } > > current->securebits &= ~issecure_mask(SECURE_KEEP_CAPS); > } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/