On 2017-09-20 12:52, Paul Moore wrote: > On Wed, Aug 23, 2017 at 7:03 AM, Richard Guy Briggs <r...@redhat.com> wrote: > > Tracefs or debugfs were causing hundreds to thousands of null PATH > > records to be associated with the init_module and finit_module SYSCALL > > records on a few modules when the following rule was in place for > > startup: > > -a always,exit -F arch=x86_64 -S init_module -F key=mod-load > > > > This happens because the parent inode is not found in the task's > > audit_names list and hence treats it as anonymous. This gives us no > > information other than a numerical device number that may no longer be > > visible upon log inspeciton, and an inode number. > > > > Fill in the filesystem type, filesystem magic number and full pathname > > from the filesystem mount point on previously null PATH records from > > entries that have an anonymous parent from the child dentry using > > dentry_path_raw(). > > > > Make the dentry argument of __audit_inode_child() non-const so that we > > can take a reference to it in the case of an anonymous parent with > > dget() and dget_parent() to be able to later print a partial path from > > the host filesystem rather than null. > > > > Since all we are given is an inode of the parent and the dentry of the > > child, finding the path from the mount point to the root of the > > filesystem is more challenging that would involve searching all > > vfsmounts from "/" until a matching dentry is found for that > > filesystem's root dentry. Even if one is found, there may be more than > > one mount point. At this point the gain seems marginal since > > knowing the filesystem type and path are a significant help in tracking > > down the source of the PATH records and being to address them. > > > > Sample output: > > type=PROCTITLE msg=audit(1488317694.446:143): > > proctitle=2F7362696E2F6D6F6470726F6265002D71002D2D006E66737634 > > type=PATH msg=audit(1488317694.446:143): item=797 > > name=tracefs(74726163):/events/nfs4/nfs4_setclientid/format inode=15969 > > dev=00:09 mode=0100444 ouid=0 ogid=0 rdev=00:00 > > obj=system_u:object_r:tracefs_t:s0 nametype=CREATE > > type=PATH msg=audit(1488317694.446:143): item=796 > > name=tracefs(74726163):/events/nfs4/nfs4_setclientid inode=15964 dev=00:09 > > mode=040755 ouid=0 ogid=0 rdev=00:00 obj=system_u:object_r:tracefs_t:s0 > > nametype=PARENT > > ... > > type=PATH msg=audit(1488317694.446:143): item=1 > > name=tracefs(74726163):/events/nfs4 inode=15571 dev=00:09 mode=040755 > > ouid=0 ogid=0 rdev=00:00 obj=system_u:object_r:tracefs_t:s0 nametype=CREATE > > type=PATH msg=audit(1488317694.446:143): item=0 > > name=tracefs(74726163):/events inode=119 dev=00:09 mode=040755 ouid=0 > > ogid=0 rdev=00:00 obj=system_u:object_r:tracefs_t:s0 nametype=PARENT > > type=UNKNOWN[1330] msg=audit(1488317694.446:143): name="nfsv4" > > type=SYSCALL msg=audit(1488317694.446:143): arch=c000003e syscall=313 > > success=yes exit=0 a0=1 a1=55d5a35ce106 a2=0 a3=1 items=798 ppid=6 pid=528 > > auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 > > tty=(none) ses=4294967295 comm="modprobe" exe="/usr/bin/kmod" > > subj=system_u:system_r:insmod_t:s0 key="mod-load" > > > > See: https://github.com/linux-audit/audit-kernel/issues/8 > > Test case: https://github.com/linux-audit/audit-testsuite/issues/42 > > > > Signed-off-by: Richard Guy Briggs <r...@redhat.com> > > > > --- > > v3: > > fix audit_buffer leak and dname error allocation leak audit_log_name > > only put audit_name->dentry if it is being replaced > > > > v2: > > minor cosmetic changes and support fs filter patch > > --- > > include/linux/audit.h | 8 ++++---- > > kernel/audit.c | 19 +++++++++++++++++++ > > kernel/audit.h | 1 + > > kernel/auditsc.c | 8 +++++++- > > 4 files changed, 31 insertions(+), 5 deletions(-) > > ... > > > diff --git a/kernel/audit.c b/kernel/audit.c > > index 59e60e0..d6e6e4e 100644 > > --- a/kernel/audit.c > > +++ b/kernel/audit.c > > @@ -72,6 +72,7 @@ > > #include <linux/freezer.h> > > #include <linux/pid_namespace.h> > > #include <net/netns/generic.h> > > +#include <linux/dcache.h> > > > > #include "audit.h" > > > > @@ -2047,6 +2048,10 @@ void audit_copy_inode(struct audit_names *name, > > const struct dentry *dentry, > > name->gid = inode->i_gid; > > name->rdev = inode->i_rdev; > > security_inode_getsecid(inode, &name->osid); > > + if (name->dentry) { > > + dput(name->dentry); > > + name->dentry = NULL; > > + } > > audit_copy_fcaps(name, dentry); > > } > > > > @@ -2088,6 +2093,20 @@ void audit_log_name(struct audit_context *context, > > struct audit_names *n, > > audit_log_n_untrustedstring(ab, n->name->name, > > n->name_len); > > } > > + } else if (n->dentry) { > > + char *fullpath; > > + const char *fullpathp = NULL; > > + > > + fullpath = kmalloc(PATH_MAX, GFP_KERNEL); > > + if (fullpath) > > + fullpathp = dentry_path_raw(n->dentry, fullpath, > > PATH_MAX); > > + if (IS_ERR(fullpathp)) { > > + fullpathp = NULL; > > + kfree(fullpath); > > + } > > + audit_log_format(ab, " name=%s(0x%lx):%s", > > + n->dentry->d_sb->s_type->name ?: "?", > > + n->dentry->d_sb->s_magic, fullpathp ?: > > "?"); > > } else > > audit_log_format(ab, " name=(null)"); > > While looking this over one more time before merging I realized that > you are missing the curly braces in the "if (fullpath)" if-statement > above. This is an easy fix, and appears to be the Right Thing, so I'm > just going to fix up the patch while merging; take a look at the > result in the audit/next tree and if you have any objections let me > know so I can back it out.
Thanks for catching that. That fix looks correct to me. > I'm also only merging this patch right now, patch 2/2 needs to wait > until the corresponding userspace is ready so we can test/verify it. I've now got tests to test patch 1 and patch 2 each seperately. They have to be two seperate manual tests because they each require a reboot with different rules. > paul moore - RGB -- Richard Guy Briggs <r...@redhat.com> Sr. S/W Engineer, Kernel Security, Base Operating Systems Remote, Ottawa, Red Hat Canada IRC: rgb, SunRaycer Voice: +1.647.777.2635, Internal: (81) 32635
