summaryrefslogtreecommitdiffstats
path: root/kernel/auditsc.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /kernel/auditsc.c
downloadop-kernel-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip
op-kernel-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'kernel/auditsc.c')
-rw-r--r--kernel/auditsc.c1015
1 files changed, 1015 insertions, 0 deletions
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
new file mode 100644
index 0000000..8c45485
--- /dev/null
+++ b/kernel/auditsc.c
@@ -0,0 +1,1015 @@
+/* auditsc.c -- System-call auditing support -*- linux-c -*-
+ * Handles all system-call specific auditing features.
+ *
+ * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
+ * All Rights Reserved.
+ *
+ * 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
+ *
+ * Written by Rickard E. (Rik) Faith <faith@redhat.com>
+ *
+ * Many of the ideas implemented here are from Stephen C. Tweedie,
+ * especially the idea of avoiding a copy by using getname.
+ *
+ * The method for actual interception of syscall entry and exit (not in
+ * this file -- see entry.S) is based on a GPL'd patch written by
+ * okir@suse.de and Copyright 2003 SuSE Linux AG.
+ *
+ */
+
+#include <linux/init.h>
+#include <asm/atomic.h>
+#include <asm/types.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+
+#include <linux/audit.h>
+#include <linux/personality.h>
+#include <linux/time.h>
+#include <asm/unistd.h>
+
+/* 0 = no checking
+ 1 = put_count checking
+ 2 = verbose put_count checking
+*/
+#define AUDIT_DEBUG 0
+
+/* No syscall auditing will take place unless audit_enabled != 0. */
+extern int audit_enabled;
+
+/* AUDIT_NAMES is the number of slots we reserve in the audit_context
+ * for saving names from getname(). */
+#define AUDIT_NAMES 20
+
+/* AUDIT_NAMES_RESERVED is the number of slots we reserve in the
+ * audit_context from being used for nameless inodes from
+ * path_lookup. */
+#define AUDIT_NAMES_RESERVED 7
+
+/* At task start time, the audit_state is set in the audit_context using
+ a per-task filter. At syscall entry, the audit_state is augmented by
+ the syscall filter. */
+enum audit_state {
+ AUDIT_DISABLED, /* Do not create per-task audit_context.
+ * No syscall-specific audit records can
+ * be generated. */
+ AUDIT_SETUP_CONTEXT, /* Create the per-task audit_context,
+ * but don't necessarily fill it in at
+ * syscall entry time (i.e., filter
+ * instead). */
+ AUDIT_BUILD_CONTEXT, /* Create the per-task audit_context,
+ * and always fill it in at syscall
+ * entry time. This makes a full
+ * syscall record available if some
+ * other part of the kernel decides it
+ * should be recorded. */
+ AUDIT_RECORD_CONTEXT /* Create the per-task audit_context,
+ * always fill it in at syscall entry
+ * time, and always write out the audit
+ * record at syscall exit time. */
+};
+
+/* When fs/namei.c:getname() is called, we store the pointer in name and
+ * we don't let putname() free it (instead we free all of the saved
+ * pointers at syscall exit time).
+ *
+ * Further, in fs/namei.c:path_lookup() we store the inode and device. */
+struct audit_names {
+ const char *name;
+ unsigned long ino;
+ dev_t dev;
+ umode_t mode;
+ uid_t uid;
+ gid_t gid;
+ dev_t rdev;
+};
+
+struct audit_aux_data {
+ struct audit_aux_data *next;
+ int type;
+};
+
+#define AUDIT_AUX_IPCPERM 0
+
+struct audit_aux_data_ipcctl {
+ struct audit_aux_data d;
+ struct ipc_perm p;
+ unsigned long qbytes;
+ uid_t uid;
+ gid_t gid;
+ mode_t mode;
+};
+
+
+/* The per-task audit context. */
+struct audit_context {
+ int in_syscall; /* 1 if task is in a syscall */
+ enum audit_state state;
+ unsigned int serial; /* serial number for record */
+ struct timespec ctime; /* time of syscall entry */
+ uid_t loginuid; /* login uid (identity) */
+ int major; /* syscall number */
+ unsigned long argv[4]; /* syscall arguments */
+ int return_valid; /* return code is valid */
+ int return_code;/* syscall return code */
+ int auditable; /* 1 if record should be written */
+ int name_count;
+ struct audit_names names[AUDIT_NAMES];
+ struct audit_context *previous; /* For nested syscalls */
+ struct audit_aux_data *aux;
+
+ /* Save things to print about task_struct */
+ pid_t pid;
+ uid_t uid, euid, suid, fsuid;
+ gid_t gid, egid, sgid, fsgid;
+ unsigned long personality;
+
+#if AUDIT_DEBUG
+ int put_count;
+ int ino_count;
+#endif
+};
+
+ /* Public API */
+/* There are three lists of rules -- one to search at task creation
+ * time, one to search at syscall entry time, and another to search at
+ * syscall exit time. */
+static LIST_HEAD(audit_tsklist);
+static LIST_HEAD(audit_entlist);
+static LIST_HEAD(audit_extlist);
+
+struct audit_entry {
+ struct list_head list;
+ struct rcu_head rcu;
+ struct audit_rule rule;
+};
+
+/* Check to see if two rules are identical. It is called from
+ * audit_del_rule during AUDIT_DEL. */
+static int audit_compare_rule(struct audit_rule *a, struct audit_rule *b)
+{
+ int i;
+
+ if (a->flags != b->flags)
+ return 1;
+
+ if (a->action != b->action)
+ return 1;
+
+ if (a->field_count != b->field_count)
+ return 1;
+
+ for (i = 0; i < a->field_count; i++) {
+ if (a->fields[i] != b->fields[i]
+ || a->values[i] != b->values[i])
+ return 1;
+ }
+
+ for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
+ if (a->mask[i] != b->mask[i])
+ return 1;
+
+ return 0;
+}
+
+/* Note that audit_add_rule and audit_del_rule are called via
+ * audit_receive() in audit.c, and are protected by
+ * audit_netlink_sem. */
+static inline int audit_add_rule(struct audit_entry *entry,
+ struct list_head *list)
+{
+ if (entry->rule.flags & AUDIT_PREPEND) {
+ entry->rule.flags &= ~AUDIT_PREPEND;
+ list_add_rcu(&entry->list, list);
+ } else {
+ list_add_tail_rcu(&entry->list, list);
+ }
+ return 0;
+}
+
+static void audit_free_rule(struct rcu_head *head)
+{
+ struct audit_entry *e = container_of(head, struct audit_entry, rcu);
+ kfree(e);
+}
+
+/* Note that audit_add_rule and audit_del_rule are called via
+ * audit_receive() in audit.c, and are protected by
+ * audit_netlink_sem. */
+static inline int audit_del_rule(struct audit_rule *rule,
+ struct list_head *list)
+{
+ struct audit_entry *e;
+
+ /* Do not use the _rcu iterator here, since this is the only
+ * deletion routine. */
+ list_for_each_entry(e, list, list) {
+ if (!audit_compare_rule(rule, &e->rule)) {
+ list_del_rcu(&e->list);
+ call_rcu(&e->rcu, audit_free_rule);
+ return 0;
+ }
+ }
+ return -EFAULT; /* No matching rule */
+}
+
+#ifdef CONFIG_NET
+/* Copy rule from user-space to kernel-space. Called during
+ * AUDIT_ADD. */
+static int audit_copy_rule(struct audit_rule *d, struct audit_rule *s)
+{
+ int i;
+
+ if (s->action != AUDIT_NEVER
+ && s->action != AUDIT_POSSIBLE
+ && s->action != AUDIT_ALWAYS)
+ return -1;
+ if (s->field_count < 0 || s->field_count > AUDIT_MAX_FIELDS)
+ return -1;
+
+ d->flags = s->flags;
+ d->action = s->action;
+ d->field_count = s->field_count;
+ for (i = 0; i < d->field_count; i++) {
+ d->fields[i] = s->fields[i];
+ d->values[i] = s->values[i];
+ }
+ for (i = 0; i < AUDIT_BITMASK_SIZE; i++) d->mask[i] = s->mask[i];
+ return 0;
+}
+
+int audit_receive_filter(int type, int pid, int uid, int seq, void *data)
+{
+ u32 flags;
+ struct audit_entry *entry;
+ int err = 0;
+
+ switch (type) {
+ case AUDIT_LIST:
+ /* The *_rcu iterators not needed here because we are
+ always called with audit_netlink_sem held. */
+ list_for_each_entry(entry, &audit_tsklist, list)
+ audit_send_reply(pid, seq, AUDIT_LIST, 0, 1,
+ &entry->rule, sizeof(entry->rule));
+ list_for_each_entry(entry, &audit_entlist, list)
+ audit_send_reply(pid, seq, AUDIT_LIST, 0, 1,
+ &entry->rule, sizeof(entry->rule));
+ list_for_each_entry(entry, &audit_extlist, list)
+ audit_send_reply(pid, seq, AUDIT_LIST, 0, 1,
+ &entry->rule, sizeof(entry->rule));
+ audit_send_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
+ break;
+ case AUDIT_ADD:
+ if (!(entry = kmalloc(sizeof(*entry), GFP_KERNEL)))
+ return -ENOMEM;
+ if (audit_copy_rule(&entry->rule, data)) {
+ kfree(entry);
+ return -EINVAL;
+ }
+ flags = entry->rule.flags;
+ if (!err && (flags & AUDIT_PER_TASK))
+ err = audit_add_rule(entry, &audit_tsklist);
+ if (!err && (flags & AUDIT_AT_ENTRY))
+ err = audit_add_rule(entry, &audit_entlist);
+ if (!err && (flags & AUDIT_AT_EXIT))
+ err = audit_add_rule(entry, &audit_extlist);
+ break;
+ case AUDIT_DEL:
+ flags =((struct audit_rule *)data)->flags;
+ if (!err && (flags & AUDIT_PER_TASK))
+ err = audit_del_rule(data, &audit_tsklist);
+ if (!err && (flags & AUDIT_AT_ENTRY))
+ err = audit_del_rule(data, &audit_entlist);
+ if (!err && (flags & AUDIT_AT_EXIT))
+ err = audit_del_rule(data, &audit_extlist);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return err;
+}
+#endif
+
+/* Compare a task_struct with an audit_rule. Return 1 on match, 0
+ * otherwise. */
+static int audit_filter_rules(struct task_struct *tsk,
+ struct audit_rule *rule,
+ struct audit_context *ctx,
+ enum audit_state *state)
+{
+ int i, j;
+
+ for (i = 0; i < rule->field_count; i++) {
+ u32 field = rule->fields[i] & ~AUDIT_NEGATE;
+ u32 value = rule->values[i];
+ int result = 0;
+
+ switch (field) {
+ case AUDIT_PID:
+ result = (tsk->pid == value);
+ break;
+ case AUDIT_UID:
+ result = (tsk->uid == value);
+ break;
+ case AUDIT_EUID:
+ result = (tsk->euid == value);
+ break;
+ case AUDIT_SUID:
+ result = (tsk->suid == value);
+ break;
+ case AUDIT_FSUID:
+ result = (tsk->fsuid == value);
+ break;
+ case AUDIT_GID:
+ result = (tsk->gid == value);
+ break;
+ case AUDIT_EGID:
+ result = (tsk->egid == value);
+ break;
+ case AUDIT_SGID:
+ result = (tsk->sgid == value);
+ break;
+ case AUDIT_FSGID:
+ result = (tsk->fsgid == value);
+ break;
+ case AUDIT_PERS:
+ result = (tsk->personality == value);
+ break;
+
+ case AUDIT_EXIT:
+ if (ctx && ctx->return_valid)
+ result = (ctx->return_code == value);
+ break;
+ case AUDIT_SUCCESS:
+ if (ctx && ctx->return_valid)
+ result = (ctx->return_code >= 0);
+ break;
+ case AUDIT_DEVMAJOR:
+ if (ctx) {
+ for (j = 0; j < ctx->name_count; j++) {
+ if (MAJOR(ctx->names[j].dev)==value) {
+ ++result;
+ break;
+ }
+ }
+ }
+ break;
+ case AUDIT_DEVMINOR:
+ if (ctx) {
+ for (j = 0; j < ctx->name_count; j++) {
+ if (MINOR(ctx->names[j].dev)==value) {
+ ++result;
+ break;
+ }
+ }
+ }
+ break;
+ case AUDIT_INODE:
+ if (ctx) {
+ for (j = 0; j < ctx->name_count; j++) {
+ if (ctx->names[j].ino == value) {
+ ++result;
+ break;
+ }
+ }
+ }
+ break;
+ case AUDIT_LOGINUID:
+ result = 0;
+ if (ctx)
+ result = (ctx->loginuid == value);
+ break;
+ case AUDIT_ARG0:
+ case AUDIT_ARG1:
+ case AUDIT_ARG2:
+ case AUDIT_ARG3:
+ if (ctx)
+ result = (ctx->argv[field-AUDIT_ARG0]==value);
+ break;
+ }
+
+ if (rule->fields[i] & AUDIT_NEGATE)
+ result = !result;
+ if (!result)
+ return 0;
+ }
+ switch (rule->action) {
+ case AUDIT_NEVER: *state = AUDIT_DISABLED; break;
+ case AUDIT_POSSIBLE: *state = AUDIT_BUILD_CONTEXT; break;
+ case AUDIT_ALWAYS: *state = AUDIT_RECORD_CONTEXT; break;
+ }
+ return 1;
+}
+
+/* At process creation time, we can determine if system-call auditing is
+ * completely disabled for this task. Since we only have the task
+ * structure at this point, we can only check uid and gid.
+ */
+static enum audit_state audit_filter_task(struct task_struct *tsk)
+{
+ struct audit_entry *e;
+ enum audit_state state;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(e, &audit_tsklist, list) {
+ if (audit_filter_rules(tsk, &e->rule, NULL, &state)) {
+ rcu_read_unlock();
+ return state;
+ }
+ }
+ rcu_read_unlock();
+ return AUDIT_BUILD_CONTEXT;
+}
+
+/* At syscall entry and exit time, this filter is called if the
+ * audit_state is not low enough that auditing cannot take place, but is
+ * also not high enough that we already know we have to write and audit
+ * record (i.e., the state is AUDIT_SETUP_CONTEXT or AUDIT_BUILD_CONTEXT).
+ */
+static enum audit_state audit_filter_syscall(struct task_struct *tsk,
+ struct audit_context *ctx,
+ struct list_head *list)
+{
+ struct audit_entry *e;
+ enum audit_state state;
+ int word = AUDIT_WORD(ctx->major);
+ int bit = AUDIT_BIT(ctx->major);
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(e, list, list) {
+ if ((e->rule.mask[word] & bit) == bit
+ && audit_filter_rules(tsk, &e->rule, ctx, &state)) {
+ rcu_read_unlock();
+ return state;
+ }
+ }
+ rcu_read_unlock();
+ return AUDIT_BUILD_CONTEXT;
+}
+
+/* This should be called with task_lock() held. */
+static inline struct audit_context *audit_get_context(struct task_struct *tsk,
+ int return_valid,
+ int return_code)
+{
+ struct audit_context *context = tsk->audit_context;
+
+ if (likely(!context))
+ return NULL;
+ context->return_valid = return_valid;
+ context->return_code = return_code;
+
+ if (context->in_syscall && !context->auditable) {
+ enum audit_state state;
+ state = audit_filter_syscall(tsk, context, &audit_extlist);
+ if (state == AUDIT_RECORD_CONTEXT)
+ context->auditable = 1;
+ }
+
+ context->pid = tsk->pid;
+ context->uid = tsk->uid;
+ context->gid = tsk->gid;
+ context->euid = tsk->euid;
+ context->suid = tsk->suid;
+ context->fsuid = tsk->fsuid;
+ context->egid = tsk->egid;
+ context->sgid = tsk->sgid;
+ context->fsgid = tsk->fsgid;
+ context->personality = tsk->personality;
+ tsk->audit_context = NULL;
+ return context;
+}
+
+static inline void audit_free_names(struct audit_context *context)
+{
+ int i;
+
+#if AUDIT_DEBUG == 2
+ if (context->auditable
+ ||context->put_count + context->ino_count != context->name_count) {
+ printk(KERN_ERR "audit.c:%d(:%d): major=%d in_syscall=%d"
+ " name_count=%d put_count=%d"
+ " ino_count=%d [NOT freeing]\n",
+ __LINE__,
+ context->serial, context->major, context->in_syscall,
+ context->name_count, context->put_count,
+ context->ino_count);
+ for (i = 0; i < context->name_count; i++)
+ printk(KERN_ERR "names[%d] = %p = %s\n", i,
+ context->names[i].name,
+ context->names[i].name);
+ dump_stack();
+ return;
+ }
+#endif
+#if AUDIT_DEBUG
+ context->put_count = 0;
+ context->ino_count = 0;
+#endif
+
+ for (i = 0; i < context->name_count; i++)
+ if (context->names[i].name)
+ __putname(context->names[i].name);
+ context->name_count = 0;
+}
+
+static inline void audit_free_aux(struct audit_context *context)
+{
+ struct audit_aux_data *aux;
+
+ while ((aux = context->aux)) {
+ context->aux = aux->next;
+ kfree(aux);
+ }
+}
+
+static inline void audit_zero_context(struct audit_context *context,
+ enum audit_state state)
+{
+ uid_t loginuid = context->loginuid;
+
+ memset(context, 0, sizeof(*context));
+ context->state = state;
+ context->loginuid = loginuid;
+}
+
+static inline struct audit_context *audit_alloc_context(enum audit_state state)
+{
+ struct audit_context *context;
+
+ if (!(context = kmalloc(sizeof(*context), GFP_KERNEL)))
+ return NULL;
+ audit_zero_context(context, state);
+ return context;
+}
+
+/* Filter on the task information and allocate a per-task audit context
+ * if necessary. Doing so turns on system call auditing for the
+ * specified task. This is called from copy_process, so no lock is
+ * needed. */
+int audit_alloc(struct task_struct *tsk)
+{
+ struct audit_context *context;
+ enum audit_state state;
+
+ if (likely(!audit_enabled))
+ return 0; /* Return if not auditing. */
+
+ state = audit_filter_task(tsk);
+ if (likely(state == AUDIT_DISABLED))
+ return 0;
+
+ if (!(context = audit_alloc_context(state))) {
+ audit_log_lost("out of memory in audit_alloc");
+ return -ENOMEM;
+ }
+
+ /* Preserve login uid */
+ context->loginuid = -1;
+ if (current->audit_context)
+ context->loginuid = current->audit_context->loginuid;
+
+ tsk->audit_context = context;
+ set_tsk_thread_flag(tsk, TIF_SYSCALL_AUDIT);
+ return 0;
+}
+
+static inline void audit_free_context(struct audit_context *context)
+{
+ struct audit_context *previous;
+ int count = 0;
+
+ do {
+ previous = context->previous;
+ if (previous || (count && count < 10)) {
+ ++count;
+ printk(KERN_ERR "audit(:%d): major=%d name_count=%d:"
+ " freeing multiple contexts (%d)\n",
+ context->serial, context->major,
+ context->name_count, count);
+ }
+ audit_free_names(context);
+ audit_free_aux(context);
+ kfree(context);
+ context = previous;
+ } while (context);
+ if (count >= 10)
+ printk(KERN_ERR "audit: freed %d contexts\n", count);
+}
+
+static void audit_log_exit(struct audit_context *context)
+{
+ int i;
+ struct audit_buffer *ab;
+
+ ab = audit_log_start(context);
+ if (!ab)
+ return; /* audit_panic has been called */
+ audit_log_format(ab, "syscall=%d", context->major);
+ if (context->personality != PER_LINUX)
+ audit_log_format(ab, " per=%lx", context->personality);
+ if (context->return_valid)
+ audit_log_format(ab, " exit=%d", context->return_code);
+ audit_log_format(ab,
+ " a0=%lx a1=%lx a2=%lx a3=%lx items=%d"
+ " pid=%d loginuid=%d uid=%d gid=%d"
+ " euid=%d suid=%d fsuid=%d"
+ " egid=%d sgid=%d fsgid=%d",
+ context->argv[0],
+ context->argv[1],
+ context->argv[2],
+ context->argv[3],
+ context->name_count,
+ context->pid,
+ context->loginuid,
+ context->uid,
+ context->gid,
+ context->euid, context->suid, context->fsuid,
+ context->egid, context->sgid, context->fsgid);
+ audit_log_end(ab);
+ while (context->aux) {
+ struct audit_aux_data *aux;
+
+ ab = audit_log_start(context);
+ if (!ab)
+ continue; /* audit_panic has been called */
+
+ aux = context->aux;
+ context->aux = aux->next;
+
+ audit_log_format(ab, "auxitem=%d", aux->type);
+ switch (aux->type) {
+ case AUDIT_AUX_IPCPERM: {
+ struct audit_aux_data_ipcctl *axi = (void *)aux;
+ audit_log_format(ab,
+ " qbytes=%lx uid=%d gid=%d mode=%x",
+ axi->qbytes, axi->uid, axi->gid, axi->mode);
+ }
+ }
+ audit_log_end(ab);
+ kfree(aux);
+ }
+
+ for (i = 0; i < context->name_count; i++) {
+ ab = audit_log_start(context);
+ if (!ab)
+ continue; /* audit_panic has been called */
+ audit_log_format(ab, "item=%d", i);
+ if (context->names[i].name)
+ audit_log_format(ab, " name=%s",
+ context->names[i].name);
+ if (context->names[i].ino != (unsigned long)-1)
+ audit_log_format(ab, " inode=%lu dev=%02x:%02x mode=%#o"
+ " uid=%d gid=%d rdev=%02x:%02x",
+ context->names[i].ino,
+ MAJOR(context->names[i].dev),
+ MINOR(context->names[i].dev),
+ context->names[i].mode,
+ context->names[i].uid,
+ context->names[i].gid,
+ MAJOR(context->names[i].rdev),
+ MINOR(context->names[i].rdev));
+ audit_log_end(ab);
+ }
+}
+
+/* Free a per-task audit context. Called from copy_process and
+ * __put_task_struct. */
+void audit_free(struct task_struct *tsk)
+{
+ struct audit_context *context;
+
+ task_lock(tsk);
+ context = audit_get_context(tsk, 0, 0);
+ task_unlock(tsk);
+
+ if (likely(!context))
+ return;
+
+ /* Check for system calls that do not go through the exit
+ * function (e.g., exit_group), then free context block. */
+ if (context->in_syscall && context->auditable)
+ audit_log_exit(context);
+
+ audit_free_context(context);
+}
+
+/* Compute a serial number for the audit record. Audit records are
+ * written to user-space as soon as they are generated, so a complete
+ * audit record may be written in several pieces. The timestamp of the
+ * record and this serial number are used by the user-space daemon to
+ * determine which pieces belong to the same audit record. The
+ * (timestamp,serial) tuple is unique for each syscall and is live from
+ * syscall entry to syscall exit.
+ *
+ * Atomic values are only guaranteed to be 24-bit, so we count down.
+ *
+ * NOTE: Another possibility is to store the formatted records off the
+ * audit context (for those records that have a context), and emit them
+ * all at syscall exit. However, this could delay the reporting of
+ * significant errors until syscall exit (or never, if the system
+ * halts). */
+static inline unsigned int audit_serial(void)
+{
+ static atomic_t serial = ATOMIC_INIT(0xffffff);
+ unsigned int a, b;
+
+ do {
+ a = atomic_read(&serial);
+ if (atomic_dec_and_test(&serial))
+ atomic_set(&serial, 0xffffff);
+ b = atomic_read(&serial);
+ } while (b != a - 1);
+
+ return 0xffffff - b;
+}
+
+/* Fill in audit context at syscall entry. This only happens if the
+ * audit context was created when the task was created and the state or
+ * filters demand the audit context be built. If the state from the
+ * per-task filter or from the per-syscall filter is AUDIT_RECORD_CONTEXT,
+ * then the record will be written at syscall exit time (otherwise, it
+ * will only be written if another part of the kernel requests that it
+ * be written). */
+void audit_syscall_entry(struct task_struct *tsk, int major,
+ unsigned long a1, unsigned long a2,
+ unsigned long a3, unsigned long a4)
+{
+ struct audit_context *context = tsk->audit_context;
+ enum audit_state state;
+
+ BUG_ON(!context);
+
+ /* This happens only on certain architectures that make system
+ * calls in kernel_thread via the entry.S interface, instead of
+ * with direct calls. (If you are porting to a new
+ * architecture, hitting this condition can indicate that you
+ * got the _exit/_leave calls backward in entry.S.)
+ *
+ * i386 no
+ * x86_64 no
+ * ppc64 yes (see arch/ppc64/kernel/misc.S)
+ *
+ * This also happens with vm86 emulation in a non-nested manner
+ * (entries without exits), so this case must be caught.
+ */
+ if (context->in_syscall) {
+ struct audit_context *newctx;
+
+#if defined(__NR_vm86) && defined(__NR_vm86old)
+ /* vm86 mode should only be entered once */
+ if (major == __NR_vm86 || major == __NR_vm86old)
+ return;
+#endif
+#if AUDIT_DEBUG
+ printk(KERN_ERR
+ "audit(:%d) pid=%d in syscall=%d;"
+ " entering syscall=%d\n",
+ context->serial, tsk->pid, context->major, major);
+#endif
+ newctx = audit_alloc_context(context->state);
+ if (newctx) {
+ newctx->previous = context;
+ context = newctx;
+ tsk->audit_context = newctx;
+ } else {
+ /* If we can't alloc a new context, the best we
+ * can do is to leak memory (any pending putname
+ * will be lost). The only other alternative is
+ * to abandon auditing. */
+ audit_zero_context(context, context->state);
+ }
+ }
+ BUG_ON(context->in_syscall || context->name_count);
+
+ if (!audit_enabled)
+ return;
+
+ context->major = major;
+ context->argv[0] = a1;
+ context->argv[1] = a2;
+ context->argv[2] = a3;
+ context->argv[3] = a4;
+
+ state = context->state;
+ if (state == AUDIT_SETUP_CONTEXT || state == AUDIT_BUILD_CONTEXT)
+ state = audit_filter_syscall(tsk, context, &audit_entlist);
+ if (likely(state == AUDIT_DISABLED))
+ return;
+
+ context->serial = audit_serial();
+ context->ctime = CURRENT_TIME;
+ context->in_syscall = 1;
+ context->auditable = !!(state == AUDIT_RECORD_CONTEXT);
+}
+
+/* Tear down after system call. If the audit context has been marked as
+ * auditable (either because of the AUDIT_RECORD_CONTEXT state from
+ * filtering, or because some other part of the kernel write an audit
+ * message), then write out the syscall information. In call cases,
+ * free the names stored from getname(). */
+void audit_syscall_exit(struct task_struct *tsk, int return_code)
+{
+ struct audit_context *context;
+
+ get_task_struct(tsk);
+ task_lock(tsk);
+ context = audit_get_context(tsk, 1, return_code);
+ task_unlock(tsk);
+
+ /* Not having a context here is ok, since the parent may have
+ * called __put_task_struct. */
+ if (likely(!context))
+ return;
+
+ if (context->in_syscall && context->auditable)
+ audit_log_exit(context);
+
+ context->in_syscall = 0;
+ context->auditable = 0;
+ if (context->previous) {
+ struct audit_context *new_context = context->previous;
+ context->previous = NULL;
+ audit_free_context(context);
+ tsk->audit_context = new_context;
+ } else {
+ audit_free_names(context);
+ audit_free_aux(context);
+ audit_zero_context(context, context->state);
+ tsk->audit_context = context;
+ }
+ put_task_struct(tsk);
+}
+
+/* Add a name to the list. Called from fs/namei.c:getname(). */
+void audit_getname(const char *name)
+{
+ struct audit_context *context = current->audit_context;
+
+ if (!context || IS_ERR(name) || !name)
+ return;
+
+ if (!context->in_syscall) {
+#if AUDIT_DEBUG == 2
+ printk(KERN_ERR "%s:%d(:%d): ignoring getname(%p)\n",
+ __FILE__, __LINE__, context->serial, name);
+ dump_stack();
+#endif
+ return;
+ }
+ BUG_ON(context->name_count >= AUDIT_NAMES);
+ context->names[context->name_count].name = name;
+ context->names[context->name_count].ino = (unsigned long)-1;
+ ++context->name_count;
+}
+
+/* Intercept a putname request. Called from
+ * include/linux/fs.h:putname(). If we have stored the name from
+ * getname in the audit context, then we delay the putname until syscall
+ * exit. */
+void audit_putname(const char *name)
+{
+ struct audit_context *context = current->audit_context;
+
+ BUG_ON(!context);
+ if (!context->in_syscall) {
+#if AUDIT_DEBUG == 2
+ printk(KERN_ERR "%s:%d(:%d): __putname(%p)\n",
+ __FILE__, __LINE__, context->serial, name);
+ if (context->name_count) {
+ int i;
+ for (i = 0; i < context->name_count; i++)
+ printk(KERN_ERR "name[%d] = %p = %s\n", i,
+ context->names[i].name,
+ context->names[i].name);
+ }
+#endif
+ __putname(name);
+ }
+#if AUDIT_DEBUG
+ else {
+ ++context->put_count;
+ if (context->put_count > context->name_count) {
+ printk(KERN_ERR "%s:%d(:%d): major=%d"
+ " in_syscall=%d putname(%p) name_count=%d"
+ " put_count=%d\n",
+ __FILE__, __LINE__,
+ context->serial, context->major,
+ context->in_syscall, name, context->name_count,
+ context->put_count);
+ dump_stack();
+ }
+ }
+#endif
+}
+
+/* Store the inode and device from a lookup. Called from
+ * fs/namei.c:path_lookup(). */
+void audit_inode(const char *name, const struct inode *inode)
+{
+ int idx;
+ struct audit_context *context = current->audit_context;
+
+ if (!context->in_syscall)
+ return;
+ if (context->name_count
+ && context->names[context->name_count-1].name
+ && context->names[context->name_count-1].name == name)
+ idx = context->name_count - 1;
+ else if (context->name_count > 1
+ && context->names[context->name_count-2].name
+ && context->names[context->name_count-2].name == name)
+ idx = context->name_count - 2;
+ else {
+ /* FIXME: how much do we care about inodes that have no
+ * associated name? */
+ if (context->name_count >= AUDIT_NAMES - AUDIT_NAMES_RESERVED)
+ return;
+ idx = context->name_count++;
+ context->names[idx].name = NULL;
+#if AUDIT_DEBUG
+ ++context->ino_count;
+#endif
+ }
+ context->names[idx].ino = inode->i_ino;
+ context->names[idx].dev = inode->i_sb->s_dev;
+ context->names[idx].mode = inode->i_mode;
+ context->names[idx].uid = inode->i_uid;
+ context->names[idx].gid = inode->i_gid;
+ context->names[idx].rdev = inode->i_rdev;
+}
+
+void audit_get_stamp(struct audit_context *ctx,
+ struct timespec *t, int *serial)
+{
+ if (ctx) {
+ t->tv_sec = ctx->ctime.tv_sec;
+ t->tv_nsec = ctx->ctime.tv_nsec;
+ *serial = ctx->serial;
+ ctx->auditable = 1;
+ } else {
+ *t = CURRENT_TIME;
+ *serial = 0;
+ }
+}
+
+extern int audit_set_type(struct audit_buffer *ab, int type);
+
+int audit_set_loginuid(struct audit_context *ctx, uid_t loginuid)
+{
+ if (ctx) {
+ struct audit_buffer *ab;
+
+ ab = audit_log_start(NULL);
+ if (ab) {
+ audit_log_format(ab, "login pid=%d uid=%u "
+ "old loginuid=%u new loginuid=%u",
+ ctx->pid, ctx->uid, ctx->loginuid, loginuid);
+ audit_set_type(ab, AUDIT_LOGIN);
+ audit_log_end(ab);
+ }
+ ctx->loginuid = loginuid;
+ }
+ return 0;
+}
+
+uid_t audit_get_loginuid(struct audit_context *ctx)
+{
+ return ctx ? ctx->loginuid : -1;
+}
+
+int audit_ipc_perms(unsigned long qbytes, uid_t uid, gid_t gid, mode_t mode)
+{
+ struct audit_aux_data_ipcctl *ax;
+ struct audit_context *context = current->audit_context;
+
+ if (likely(!context))
+ return 0;
+
+ ax = kmalloc(sizeof(*ax), GFP_KERNEL);
+ if (!ax)
+ return -ENOMEM;
+
+ ax->qbytes = qbytes;
+ ax->uid = uid;
+ ax->gid = gid;
+ ax->mode = mode;
+
+ ax->d.type = AUDIT_AUX_IPCPERM;
+ ax->d.next = context->aux;
+ context->aux = (void *)ax;
+ return 0;
+}
OpenPOWER on IntegriCloud