[PATCH 1/3] audit: implement audit by executable

This patch implements the ability to filter on the executable. It is clearly incomplete! This patch adds the inode/dev of the executable at the moment the rule is loaded. It does not update if the executable is updated/moved/whatever. That should be added. But at this moment, this patch works. Based-on-user-interface-by: Richard Guy Briggs <rgb(a)redhat.com&gt; Cc: rgb(a)redhat.com Based-on-idea-by: Peter Moody <pmoody(a)google.com&gt; Cc: pmoody(a)google.com Signed-off-by: Eric Paris <eparis(a)redhat.com&gt; --- include/linux/audit.h | 1 + include/uapi/linux/audit.h | 2 + kernel/Makefile | 2 +- kernel/audit.h | 27 +++++++++++ kernel/audit_exe.c | 113 +++++++++++++++++++++++++++++++++++++++++++++ kernel/auditfilter.c | 43 +++++++++++++++++ kernel/auditsc.c | 16 +++++++ 7 files changed, 203 insertions(+), 1 deletion(-) create mode 100644 kernel/audit_exe.c diff --git a/include/linux/audit.h b/include/linux/audit.h index 1ae0089..84e7bc4 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -59,6 +59,7 @@ struct audit_krule { struct audit_field *inode_f; /* quick access to an inode field */ struct audit_watch *watch; /* associated watch */ struct audit_tree *tree; /* associated watched tree */ + struct audit_exe *exe; struct list_head rlist; /* entry in audit_{watch,tree}.rules list */ struct list_head list; /* for AUDIT_LIST* purposes only */ u64 prio; diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index d95eba0..e916088 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -266,6 +266,8 @@ #define AUDIT_OBJ_UID 109 #define AUDIT_OBJ_GID 110 #define AUDIT_FIELD_COMPARE 111 +#define AUDIT_EXE 112 +#define AUDIT_EXE_CHILDREN 113 #define AUDIT_ARG0 200 #define AUDIT_ARG1 (AUDIT_ARG0+1) diff --git a/kernel/Makefile b/kernel/Makefile index bc010ee..a1d5715 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -61,7 +61,7 @@ obj-$(CONFIG_SMP) += stop_machine.o obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o obj-$(CONFIG_AUDIT) += audit.o auditfilter.o obj-$(CONFIG_AUDITSYSCALL) += auditsc.o -obj-$(CONFIG_AUDIT_WATCH) += audit_watch.o +obj-$(CONFIG_AUDIT_WATCH) += audit_watch.o audit_exe.o obj-$(CONFIG_AUDIT_TREE) += audit_tree.o obj-$(CONFIG_GCOV_KERNEL) += gcov/ obj-$(CONFIG_KPROBES) += kprobes.o diff --git a/kernel/audit.h b/kernel/audit.h index 7bb6573..58ed955 100644 --- a/kernel/audit.h +++ b/kernel/audit.h @@ -56,6 +56,7 @@ enum audit_state { /* Rule lists */ struct audit_watch; +struct audit_exe; struct audit_tree; struct audit_chunk; @@ -280,6 +281,13 @@ extern int audit_add_watch(struct audit_krule *krule, struct list_head **list); extern void audit_remove_watch_rule(struct audit_krule *krule); extern char *audit_watch_path(struct audit_watch *watch); extern int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev); + +int audit_make_exe_rule(struct audit_krule *krule, char *pathname, int len, u32 op); +void audit_remove_exe_rule(struct audit_krule *krule); +char *audit_exe_path(struct audit_exe *exe); +int audit_dup_exe(struct audit_krule *new, struct audit_krule *old); +int audit_exe_compare(struct task_struct *tsk, struct audit_exe *exe); + #else #define audit_put_watch(w) {} #define audit_get_watch(w) {} @@ -289,6 +297,25 @@ extern int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev #define audit_watch_path(w) "" #define audit_watch_compare(w, i, d) 0 +static inline int audit_make_exe_rule(struct audit_krule *krule, char *pathname, int len, u32 op) { + return -EINVAL; +} +static inline void audit_remove_exe_rule(struct audit_krule *krule) { + BUG(); + return 0; +} +static inline char *audit_exe_path(struct audit_exe *exe) { + BUG(); + return ""; +} +static inline int audit_dup_exe(struct audit_krule *new, struct audit_krule *old) { + BUG(); + return -EINVAL +} +static inline int audit_exe_compare(struct task_struct *tsk, struct audit_exe *exe) { + BUG(); + return 0; +} #endif /* CONFIG_AUDIT_WATCH */ #ifdef CONFIG_AUDIT_TREE diff --git a/kernel/audit_exe.c b/kernel/audit_exe.c new file mode 100644 index 0000000..09c436c --- /dev/null +++ b/kernel/audit_exe.c @@ -0,0 +1,113 @@ +/* audit_exe.c -- filtering of audit events + * + * Copyright 2014 Red Hat, Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/kernel.h> +#include <linux/audit.h> +#include <linux/mutex.h> +#include <linux/fs.h> +#include <linux/namei.h> +#include <linux/slab.h> +#include "audit.h" + +struct audit_exe { + char *pathname; + unsigned long ino; + dev_t dev; +}; + +/* Translate a watch string to kernel respresentation. */ +int audit_make_exe_rule(struct audit_krule *krule, char *pathname, int len, u32 op) +{ + struct audit_exe *exe; + struct path path; + struct dentry *dentry; + unsigned long ino; + dev_t dev; + + if (pathname[0] != '/' || pathname[len-1] == '/') + return -EINVAL; + + dentry = kern_path_locked(pathname, &path); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + mutex_unlock(&path.dentry->d_inode->i_mutex); + + if (!dentry->d_inode) + return -ENOENT; + dev = dentry->d_inode->i_sb->s_dev; + ino = dentry->d_inode->i_ino; + dput(dentry); + + exe = kmalloc(sizeof(*exe), GFP_KERNEL); + if (!exe) + return -ENOMEM; + exe->ino = ino; + exe->dev = dev; + exe->pathname = pathname; + krule->exe = exe; + + return 0; +} + +void audit_remove_exe_rule(struct audit_krule *krule) +{ + struct audit_exe *exe; + + exe = krule->exe; + krule->exe = NULL; + kfree(exe->pathname); + kfree(exe); +} + +char *audit_exe_path(struct audit_exe *exe) +{ + return exe->pathname; +} + +int audit_dup_exe(struct audit_krule *new, struct audit_krule *old) +{ + struct audit_exe *exe; + + exe = kmalloc(sizeof(*exe), GFP_KERNEL); + if (!exe) + return -ENOMEM; + + exe->pathname = kstrdup(old->exe->pathname, GFP_KERNEL); + if (!exe->pathname) { + kfree(exe); + return -ENOMEM; + } + + exe->ino = old->exe->ino; + exe->dev = old->exe->dev; + new->exe = exe; + + return 0; +} + +int audit_exe_compare(struct task_struct *tsk, struct audit_exe *exe) +{ + if (tsk->mm->exe_file->f_inode->i_ino != exe->ino) + return 0; + if (tsk->mm->exe_file->f_inode->i_sb->s_dev != exe->dev) + return 0; + return 1; +} diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c index 8e9bc9c..9caeaf5 100644 --- a/kernel/auditfilter.c +++ b/kernel/auditfilter.c @@ -390,6 +390,13 @@ static int audit_field_valid(struct audit_entry *entry, struct audit_field *f) if (f->val > AUDIT_MAX_FIELD_COMPARE) return -EINVAL; break; + case AUDIT_EXE: + case AUDIT_EXE_CHILDREN: + if (f->op != Audit_equal) + return -EINVAL; + if (entry->rule.listnr != AUDIT_FILTER_EXIT) + return -EINVAL; + break; }; return 0; } @@ -541,6 +548,23 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data, entry->rule.buflen += f->val; entry->rule.filterkey = str; break; + case AUDIT_EXE: + case AUDIT_EXE_CHILDREN: + if (entry->rule.exe || f->val > PATH_MAX) + goto exit_free; + str = audit_unpack_string(&bufp, &remain, f->val); + if (IS_ERR(str)) { + err = PTR_ERR(str); + goto exit_free; + } + entry->rule.buflen += f->val; + + err = audit_make_exe_rule(&entry->rule, str, f->val, f->op); + if (err) { + kfree(str); + goto exit_free; + } + break; } } @@ -619,6 +643,11 @@ static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule) data->buflen += data->values[i] = audit_pack_string(&bufp, krule->filterkey); break; + case AUDIT_EXE: + case AUDIT_EXE_CHILDREN: + data->buflen += data->values[i] = + audit_pack_string(&bufp, audit_exe_path(krule->exe)); + break; default: data->values[i] = f->val; } @@ -674,6 +703,13 @@ static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b) if (strcmp(a->filterkey, b->filterkey)) return 1; break; + case AUDIT_EXE: + case AUDIT_EXE_CHILDREN: + /* both paths exist based on above type compare */ + if (strcmp(audit_exe_path(a->exe), + audit_exe_path(b->exe))) + return 1; + break; case AUDIT_UID: case AUDIT_EUID: case AUDIT_SUID: @@ -795,6 +831,11 @@ struct audit_entry *audit_dupe_rule(struct audit_krule *old) err = -ENOMEM; else new->filterkey = fk; + break; + case AUDIT_EXE: + case AUDIT_EXE_CHILDREN: + err = audit_dup_exe(new, old); + break; } if (err) { audit_free_rule(entry); @@ -966,6 +1007,8 @@ static inline int audit_del_rule(struct audit_entry *entry) if (e->rule.tree) audit_remove_tree_rule(&e->rule); + if (e->rule.exe) + audit_remove_exe_rule(&e->rule); list_del_rcu(&e->list); list_del(&e->rule.list); call_rcu(&e->rcu, audit_free_rule_rcu); diff --git a/kernel/auditsc.c b/kernel/auditsc.c index b12a712..fa11362 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -48,6 +48,7 @@ #include <asm/types.h> #include <linux/atomic.h> #include <linux/fs.h> +#include <linux/dcache.h> #include <linux/namei.h> #include <linux/mm.h> #include <linux/export.h> @@ -71,6 +72,7 @@ #include <linux/capability.h> #include <linux/fs_struct.h> #include <linux/compat.h> +#include <linux/sched.h> #include <linux/ctype.h> #include "audit.h" @@ -472,6 +474,20 @@ static int audit_filter_rules(struct task_struct *tsk, result = audit_comparator(ctx->ppid, f->op, f->val); } break; + case AUDIT_EXE: + result = audit_exe_compare(tsk, rule->exe); + break; + case AUDIT_EXE_CHILDREN: + { + struct task_struct *ptsk; + for (ptsk = tsk; ptsk->parent->pid > 0; ptsk = find_task_by_vpid(ptsk->parent->pid)) { + if (audit_exe_compare(ptsk, rule->exe)) { + ++result; + break; + } + } + } + break; case AUDIT_UID: result = audit_uid_comparator(cred->uid, f->op, f->uid); break; -- 1.9.0