On 2018-02-15 18:07, Steve Grubb wrote: > On Monday, February 12, 2018 12:02:21 AM EST Richard Guy Briggs 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 for a device that may > > no longer be visible upon log inspeciton, and an inode number. > > > > Fill in the partial known pathname from the filesystem mount point to > > the leaf node 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 able to address them. > > > > Sample output: > > type=PROCTITLE msg=audit(1488317694.446:143): > > proctitle=2F7362696E2F6D6F6470726F6265002D71002D2D006E66737634 type=PATH > > msg=audit(1488317694.446:143): item=797 > > name=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 cap_fp=0000000000000000 cap_fi=0000000000000000 cap_fe=0 > > cap_fver=0 type=PATH msg=audit(1488317694.446:143): item=796 > > name=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 > > cap_fp=0000000000000000 cap_fi=0000000000000000 cap_fe=0 cap_fver=0 ... > > type=PATH msg=audit(1488317694.446:143): item=1 name=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 cap_fp=0000000000000000 > > cap_fi=0000000000000000 cap_fe=0 cap_fver=0 type=PATH > > msg=audit(1488317694.446:143): item=0 name=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 cap_fp=0000000000000000 cap_fi=0000000000000000 cap_fe=0 > > cap_fver=0 type=KERN_MODULE 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" > > Thanks for the samples, but the event above fails the ausearch-test test > suite. The "name" field in the PATH record is not properly escaped.
Let me re-run the ausearch-test on the log file from the machine in question... I don't remember if I copied the above from a recent run, or just hand-edited the output to update it. It should be fine since it was updated to now run through audit_log_untrustedstring(). > -Steve > > > 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> > > > > --- > > v4: > > fix fullpath memleak > > switch from log_format() to audit_log_untrustedstring() > > remove leading / from pathname relative to unknown mount point > > > > v3: > > fix audit_buffer leak and dname error allocation leak audit_log_name > > only put audit_name->dentry if it is being replaced > > > > v2: > > deconstify struct dentry* > > add hex prefix to fstype > > --- > > include/linux/audit.h | 8 ++++---- > > kernel/audit.c | 28 +++++++++++++++++++++++++++- > > kernel/audit.h | 1 + > > kernel/auditsc.c | 8 +++++++- > > 4 files changed, 39 insertions(+), 6 deletions(-) > > > > diff --git a/include/linux/audit.h b/include/linux/audit.h > > index af410d9..2020f1d 100644 > > --- a/include/linux/audit.h > > +++ b/include/linux/audit.h > > @@ -232,7 +232,7 @@ extern void __audit_inode(struct filename *name, const > > struct dentry *dentry, unsigned int flags); > > extern void __audit_file(const struct file *); > > extern void __audit_inode_child(struct inode *parent, > > - const struct dentry *dentry, > > + struct dentry *dentry, > > const unsigned char type); > > extern void __audit_seccomp(unsigned long syscall, long signr, int code); > > extern void __audit_ptrace(struct task_struct *t); > > @@ -297,7 +297,7 @@ static inline void audit_inode_parent_hidden(struct > > filename *name, AUDIT_INODE_PARENT | AUDIT_INODE_HIDDEN); > > } > > static inline void audit_inode_child(struct inode *parent, > > - const struct dentry *dentry, > > + struct dentry *dentry, > > const unsigned char type) { > > if (unlikely(!audit_dummy_context())) > > __audit_inode_child(parent, dentry, type); > > @@ -481,7 +481,7 @@ static inline void __audit_inode(struct filename *name, > > unsigned int flags) > > { } > > static inline void __audit_inode_child(struct inode *parent, > > - const struct dentry *dentry, > > + struct dentry *dentry, > > const unsigned char type) > > { } > > static inline void audit_inode(struct filename *name, > > @@ -495,7 +495,7 @@ static inline void audit_inode_parent_hidden(struct > > filename *name, const struct dentry *dentry) > > { } > > static inline void audit_inode_child(struct inode *parent, > > - const struct dentry *dentry, > > + struct dentry *dentry, > > const unsigned char type) > > { } > > static inline void audit_core_dumps(long signr) > > diff --git a/kernel/audit.c b/kernel/audit.c > > index 227db99..0c8d5a8 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" > > > > @@ -2056,6 +2057,10 @@ 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); > > } > > > > @@ -2097,8 +2102,29 @@ void audit_log_name(struct audit_context *context, > > struct audit_names *n, audit_log_n_untrustedstring(ab, n->name->name, > > n->name_len); > > } > > - } else > > + } 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; > > + } else { > > + while (*fullpathp == '/') > > + fullpathp++; > > + if (*fullpathp == 0) > > + fullpathp = NULL; > > + } > > + } > > + audit_log_format(ab, " name="); > > + audit_log_untrustedstring(ab, fullpathp ?: "?"); > > + if (fullpath) > > + kfree(fullpath); > > + } else { > > audit_log_format(ab, " name=(null)"); > > + } > > > > if (n->ino != AUDIT_INO_UNSET) > > audit_log_format(ab, " inode=%lu" > > diff --git a/kernel/audit.h b/kernel/audit.h > > index af5bc59..81f6865 100644 > > --- a/kernel/audit.h > > +++ b/kernel/audit.h > > @@ -85,6 +85,7 @@ struct audit_names { > > > > unsigned long ino; > > dev_t dev; > > + struct dentry *dentry; > > umode_t mode; > > kuid_t uid; > > kgid_t gid; > > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > > index e80459f..b73ede0 100644 > > --- a/kernel/auditsc.c > > +++ b/kernel/auditsc.c > > @@ -75,6 +75,7 @@ > > #include <linux/uaccess.h> > > #include <linux/fsnotify_backend.h> > > #include <uapi/linux/limits.h> > > +#include <linux/dcache.h> > > > > #include "audit.h" > > > > @@ -882,6 +883,8 @@ static inline void audit_free_names(struct > > audit_context *context) list_del(&n->list); > > if (n->name) > > putname(n->name); > > + if (n->dentry) > > + dput(n->dentry); > > if (n->should_free) > > kfree(n); > > } > > @@ -1862,7 +1865,7 @@ void __audit_file(const struct file *file) > > * unsuccessful attempts. > > */ > > void __audit_inode_child(struct inode *parent, > > - const struct dentry *dentry, > > + struct dentry *dentry, > > const unsigned char type) > > { > > struct audit_context *context = current->audit_context; > > @@ -1941,6 +1944,7 @@ void __audit_inode_child(struct inode *parent, > > if (!n) > > return; > > audit_copy_inode(n, NULL, parent); > > + n->dentry = dget_parent(dentry); > > } > > > > if (!found_child) { > > @@ -1962,6 +1966,8 @@ void __audit_inode_child(struct inode *parent, > > audit_copy_inode(found_child, dentry, inode); > > else > > found_child->ino = AUDIT_INO_UNSET; > > + if (!found_parent) > > + found_child->dentry = dget(dentry); > > } > > EXPORT_SYMBOL_GPL(__audit_inode_child); > > > > - 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
