Re: [RFC PATCH ghak9 2/3] audit: Add a function to log the path of an fd

On 2018-07-12 13:36, Ondrej Mosnacek wrote: > The function logs an FD_PATH record that is associated with the current > syscall. The record associates the given file descriptor with the > current path of the file under it (if it is possible to retrieve such > path). The reader of the log can then logically connect this information > to the syscall arguments from the SYSCALL record (based on the syscall > type). > > Record format: > type=FD_PATH msg=audit(...): fd=<file descriptor> path=<file path> > > Signed-off-by: Ondrej Mosnacek <omosnace(a)redhat.com&gt; > --- > include/linux/audit.h | 10 ++++++++++ > kernel/auditsc.c | 36 ++++++++++++++++++++++++++++++++++++ > 2 files changed, 46 insertions(+) > > diff --git a/include/linux/audit.h b/include/linux/audit.h > index 9334fbef7bae..95d338bb603a 100644 > --- a/include/linux/audit.h > +++ b/include/linux/audit.h > @@ -356,6 +356,7 @@ extern void __audit_log_capset(const struct cred *new, const struct cred *old); > extern void __audit_mmap_fd(int fd, int flags); > extern void __audit_log_kern_module(char *name); > extern void __audit_fanotify(unsigned int response); > +extern void __audit_fd_path(int fd); > > static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp) > { > @@ -458,6 +459,12 @@ static inline void audit_fanotify(unsigned int response) > __audit_fanotify(response); > } > > +static inline void audit_fd_path(int fd) > +{ > + if (fd >= 0 && !audit_dummy_context()) Isn't an fd of 0 valid?

> + __audit_fd_path(fd); > +} > + > extern int audit_n_rules; > extern int audit_signals; > #else /* CONFIG_AUDITSYSCALL */ > @@ -584,6 +591,9 @@ static inline void audit_log_kern_module(char *name) > static inline void audit_fanotify(unsigned int response) > { } > > +static inline void audit_fd_path(int fd) > +{ } > + > static inline void audit_ptrace(struct task_struct *t) > { } > #define audit_n_rules 0 > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > index d762e0b8160e..82dad69213a2 100644 > --- a/kernel/auditsc.c > +++ b/kernel/auditsc.c > @@ -74,6 +74,8 @@ > #include <linux/string.h> > #include <linux/uaccess.h> > #include <linux/fsnotify_backend.h> > +#include <linux/file.h> > +#include <linux/dcache.h> > #include <uapi/linux/limits.h> > > #include "audit.h" > @@ -2422,6 +2424,40 @@ void __audit_fanotify(unsigned int response) > AUDIT_FANOTIFY, "resp=%u", response); > } > > +void __audit_fd_path(int fd) > +{ > + struct audit_buffer *ab; > + struct file *file; > + char *buf, *path; > + > + if (!audit_enabled) > + return; > + > + file = fget_raw(fd); > + if (!file) > + return; > + > + buf = kmalloc(PATH_MAX, GFP_KERNEL); > + if (!buf) I think we need an fput(file) here.

> + return; > + > + path_get(&file->f_path); > + path = d_absolute_path(&file->f_path, buf, PATH_MAX); > + path_put(&file->f_path); > + fput(file); > + if (!path || IS_ERR(path)) > + goto free_buf; > + > + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FD_PATH); > + if (unlikely(!ab)) > + goto free_buf; > + audit_log_format(ab, "fd=%i path=", fd); > + audit_log_untrustedstring(ab, path); > + audit_log_end(ab); > +free_buf: > + kfree(buf); > +} > + > static void audit_log_task(struct audit_buffer *ab) > { > kuid_t auid, uid; - RGB -- Richard Guy Briggs <rgb(a)redhat.com&gt; 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