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authorLinus Torvalds <torvalds@linux-foundation.org>2016-07-29 17:54:17 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-29 17:54:17 -0700
commit797cee982eef9195736afc5e7f3b8f613c41d19a (patch)
tree2baf2ada982bb1c2cbe058b1378e38272cbda5d3
parentMerge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security (diff)
parentaudit: fix a double fetch in audit_log_single_execve_arg() (diff)
downloadlinux-dev-797cee982eef9195736afc5e7f3b8f613c41d19a.tar.xz
linux-dev-797cee982eef9195736afc5e7f3b8f613c41d19a.zip
Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit
Pull audit updates from Paul Moore: "Six audit patches for 4.8. There are a couple of style and minor whitespace tweaks for the logs, as well as a minor fixup to catch errors on user filter rules, however the major improvements are a fix to the s390 syscall argument masking code (reviewed by the nice s390 folks), some consolidation around the exclude filtering (less code, always a win), and a double-fetch fix for recording the execve arguments" * 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit: audit: fix a double fetch in audit_log_single_execve_arg() audit: fix whitespace in CWD record audit: add fields to exclude filter by reusing user filter s390: ensure that syscall arguments are properly masked on s390 audit: fix some horrible switch statement style crimes audit: fixup: log on errors from filter user rules
Diffstat (limited to '')
-rw-r--r--arch/s390/kernel/ptrace.c11
-rw-r--r--include/linux/audit.h2
-rw-r--r--kernel/audit.c4
-rw-r--r--kernel/audit.h2
-rw-r--r--kernel/auditfilter.c147
-rw-r--r--kernel/auditsc.c342
6 files changed, 236 insertions, 272 deletions
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index cea17010448f..9336e824e2db 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -821,6 +821,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
{
+ unsigned long mask = -1UL;
+
/*
* The sysc_tracesys code in entry.S stored the system
* call number to gprs[2].
@@ -846,9 +848,12 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
trace_sys_enter(regs, regs->gprs[2]);
- audit_syscall_entry(regs->gprs[2], regs->orig_gpr2,
- regs->gprs[3], regs->gprs[4],
- regs->gprs[5]);
+ if (is_compat_task())
+ mask = 0xffffffff;
+
+ audit_syscall_entry(regs->gprs[2], regs->orig_gpr2 & mask,
+ regs->gprs[3] &mask, regs->gprs[4] &mask,
+ regs->gprs[5] &mask);
return regs->gprs[2];
}
diff --git a/include/linux/audit.h b/include/linux/audit.h
index e38e3fc13ea8..9d4443f93db6 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -163,8 +163,6 @@ extern void audit_log_task_info(struct audit_buffer *ab,
extern int audit_update_lsm_rules(void);
/* Private API (for audit.c only) */
-extern int audit_filter_user(int type);
-extern int audit_filter_type(int type);
extern int audit_rule_change(int type, __u32 portid, int seq,
void *data, size_t datasz);
extern int audit_list_rules_send(struct sk_buff *request_skb, int seq);
diff --git a/kernel/audit.c b/kernel/audit.c
index 8d528f9930da..a8a91bd2b2a9 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -932,7 +932,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
if (!audit_enabled && msg_type != AUDIT_USER_AVC)
return 0;
- err = audit_filter_user(msg_type);
+ err = audit_filter(msg_type, AUDIT_FILTER_USER);
if (err == 1) { /* match or error */
err = 0;
if (msg_type == AUDIT_USER_TTY) {
@@ -1379,7 +1379,7 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
if (audit_initialized != AUDIT_INITIALIZED)
return NULL;
- if (unlikely(audit_filter_type(type)))
+ if (unlikely(!audit_filter(type, AUDIT_FILTER_TYPE)))
return NULL;
if (gfp_mask & __GFP_DIRECT_RECLAIM) {
diff --git a/kernel/audit.h b/kernel/audit.h
index a492f4c4e710..431444c3708b 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -331,6 +331,8 @@ extern pid_t audit_sig_pid;
extern kuid_t audit_sig_uid;
extern u32 audit_sig_sid;
+extern int audit_filter(int msgtype, unsigned int listtype);
+
#ifdef CONFIG_AUDITSYSCALL
extern int __audit_signal_info(int sig, struct task_struct *t);
static inline int audit_signal_info(int sig, struct task_struct *t)
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 94ca7b1e5e7e..85d9cac497e4 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1290,113 +1290,72 @@ int audit_compare_dname_path(const char *dname, const char *path, int parentlen)
return strncmp(p, dname, dlen);
}
-static int audit_filter_user_rules(struct audit_krule *rule, int type,
- enum audit_state *state)
+int audit_filter(int msgtype, unsigned int listtype)
{
- int i;
-
- for (i = 0; i < rule->field_count; i++) {
- struct audit_field *f = &rule->fields[i];
- pid_t pid;
- int result = 0;
- u32 sid;
-
- switch (f->type) {
- case AUDIT_PID:
- pid = task_pid_nr(current);
- result = audit_comparator(pid, f->op, f->val);
- break;
- case AUDIT_UID:
- result = audit_uid_comparator(current_uid(), f->op, f->uid);
- break;
- case AUDIT_GID:
- result = audit_gid_comparator(current_gid(), f->op, f->gid);
- break;
- case AUDIT_LOGINUID:
- result = audit_uid_comparator(audit_get_loginuid(current),
- f->op, f->uid);
- break;
- case AUDIT_LOGINUID_SET:
- result = audit_comparator(audit_loginuid_set(current),
- f->op, f->val);
- break;
- case AUDIT_MSGTYPE:
- result = audit_comparator(type, f->op, f->val);
- break;
- case AUDIT_SUBJ_USER:
- case AUDIT_SUBJ_ROLE:
- case AUDIT_SUBJ_TYPE:
- case AUDIT_SUBJ_SEN:
- case AUDIT_SUBJ_CLR:
- if (f->lsm_rule) {
- security_task_getsecid(current, &sid);
- result = security_audit_rule_match(sid,
- f->type,
- f->op,
- f->lsm_rule,
- NULL);
- }
- break;
- }
-
- if (!result)
- return 0;
- }
- switch (rule->action) {
- case AUDIT_NEVER: *state = AUDIT_DISABLED; break;
- case AUDIT_ALWAYS: *state = AUDIT_RECORD_CONTEXT; break;
- }
- return 1;
-}
-
-int audit_filter_user(int type)
-{
- enum audit_state state = AUDIT_DISABLED;
struct audit_entry *e;
- int rc, ret;
-
- ret = 1; /* Audit by default */
-
- rcu_read_lock();
- list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
- rc = audit_filter_user_rules(&e->rule, type, &state);
- if (rc) {
- if (rc > 0 && state == AUDIT_DISABLED)
- ret = 0;
- break;
- }
- }
- rcu_read_unlock();
-
- return ret;
-}
-
-int audit_filter_type(int type)
-{
- struct audit_entry *e;
- int result = 0;
+ int ret = 1; /* Audit by default */
rcu_read_lock();
- if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE]))
+ if (list_empty(&audit_filter_list[listtype]))
goto unlock_and_return;
+ list_for_each_entry_rcu(e, &audit_filter_list[listtype], list) {
+ int i, result = 0;
- list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE],
- list) {
- int i;
for (i = 0; i < e->rule.field_count; i++) {
struct audit_field *f = &e->rule.fields[i];
- if (f->type == AUDIT_MSGTYPE) {
- result = audit_comparator(type, f->op, f->val);
- if (!result)
- break;
+ pid_t pid;
+ u32 sid;
+
+ switch (f->type) {
+ case AUDIT_PID:
+ pid = task_pid_nr(current);
+ result = audit_comparator(pid, f->op, f->val);
+ break;
+ case AUDIT_UID:
+ result = audit_uid_comparator(current_uid(), f->op, f->uid);
+ break;
+ case AUDIT_GID:
+ result = audit_gid_comparator(current_gid(), f->op, f->gid);
+ break;
+ case AUDIT_LOGINUID:
+ result = audit_uid_comparator(audit_get_loginuid(current),
+ f->op, f->uid);
+ break;
+ case AUDIT_LOGINUID_SET:
+ result = audit_comparator(audit_loginuid_set(current),
+ f->op, f->val);
+ break;
+ case AUDIT_MSGTYPE:
+ result = audit_comparator(msgtype, f->op, f->val);
+ break;
+ case AUDIT_SUBJ_USER:
+ case AUDIT_SUBJ_ROLE:
+ case AUDIT_SUBJ_TYPE:
+ case AUDIT_SUBJ_SEN:
+ case AUDIT_SUBJ_CLR:
+ if (f->lsm_rule) {
+ security_task_getsecid(current, &sid);
+ result = security_audit_rule_match(sid,
+ f->type, f->op, f->lsm_rule, NULL);
+ }
+ break;
+ default:
+ goto unlock_and_return;
}
+ if (result < 0) /* error */
+ goto unlock_and_return;
+ if (!result)
+ break;
+ }
+ if (result > 0) {
+ if (e->rule.action == AUDIT_NEVER || listtype == AUDIT_FILTER_TYPE)
+ ret = 0;
+ break;
}
- if (result)
- goto unlock_and_return;
}
unlock_and_return:
rcu_read_unlock();
- return result;
+ return ret;
}
static int update_lsm_rule(struct audit_krule *r)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 2672d105cffc..5abf1dc1f91c 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -72,6 +72,7 @@
#include <linux/compat.h>
#include <linux/ctype.h>
#include <linux/string.h>
+#include <linux/uaccess.h>
#include <uapi/linux/limits.h>
#include "audit.h"
@@ -81,7 +82,8 @@
#define AUDITSC_SUCCESS 1
#define AUDITSC_FAILURE 2
-/* no execve audit message should be longer than this (userspace limits) */
+/* no execve audit message should be longer than this (userspace limits),
+ * see the note near the top of audit_log_execve_info() about this value */
#define MAX_EXECVE_AUDIT_LEN 7500
/* max length to print of cmdline/proctitle value during audit */
@@ -694,8 +696,12 @@ static int audit_filter_rules(struct task_struct *tsk,
ctx->prio = rule->prio;
}
switch (rule->action) {
- case AUDIT_NEVER: *state = AUDIT_DISABLED; break;
- case AUDIT_ALWAYS: *state = AUDIT_RECORD_CONTEXT; break;
+ case AUDIT_NEVER:
+ *state = AUDIT_DISABLED;
+ break;
+ case AUDIT_ALWAYS:
+ *state = AUDIT_RECORD_CONTEXT;
+ break;
}
return 1;
}
@@ -987,184 +993,178 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
return rc;
}
-/*
- * to_send and len_sent accounting are very loose estimates. We aren't
- * really worried about a hard cap to MAX_EXECVE_AUDIT_LEN so much as being
- * within about 500 bytes (next page boundary)
- *
- * why snprintf? an int is up to 12 digits long. if we just assumed when
- * logging that a[%d]= was going to be 16 characters long we would be wasting
- * space in every audit message. In one 7500 byte message we can log up to
- * about 1000 min size arguments. That comes down to about 50% waste of space
- * if we didn't do the snprintf to find out how long arg_num_len was.
- */
-static int audit_log_single_execve_arg(struct audit_context *context,
- struct audit_buffer **ab,
- int arg_num,
- size_t *len_sent,
- const char __user *p,
- char *buf)
+static void audit_log_execve_info(struct audit_context *context,
+ struct audit_buffer **ab)
{
- char arg_num_len_buf[12];
- const char __user *tmp_p = p;
- /* how many digits are in arg_num? 5 is the length of ' a=""' */
- size_t arg_num_len = snprintf(arg_num_len_buf, 12, "%d", arg_num) + 5;
- size_t len, len_left, to_send;
- size_t max_execve_audit_len = MAX_EXECVE_AUDIT_LEN;
- unsigned int i, has_cntl = 0, too_long = 0;
- int ret;
-
- /* strnlen_user includes the null we don't want to send */
- len_left = len = strnlen_user(p, MAX_ARG_STRLEN) - 1;
-
- /*
- * We just created this mm, if we can't find the strings
- * we just copied into it something is _very_ wrong. Similar
- * for strings that are too long, we should not have created
- * any.
- */
- if (WARN_ON_ONCE(len < 0 || len > MAX_ARG_STRLEN - 1)) {
- send_sig(SIGKILL, current, 0);
- return -1;
+ long len_max;
+ long len_rem;
+ long len_full;
+ long len_buf;
+ long len_abuf;
+ long len_tmp;
+ bool require_data;
+ bool encode;
+ unsigned int iter;
+ unsigned int arg;
+ char *buf_head;
+ char *buf;
+ const char __user *p = (const char __user *)current->mm->arg_start;
+
+ /* NOTE: this buffer needs to be large enough to hold all the non-arg
+ * data we put in the audit record for this argument (see the
+ * code below) ... at this point in time 96 is plenty */
+ char abuf[96];
+
+ /* NOTE: we set MAX_EXECVE_AUDIT_LEN to a rather arbitrary limit, the
+ * current value of 7500 is not as important as the fact that it
+ * is less than 8k, a setting of 7500 gives us plenty of wiggle
+ * room if we go over a little bit in the logging below */
+ WARN_ON_ONCE(MAX_EXECVE_AUDIT_LEN > 7500);
+ len_max = MAX_EXECVE_AUDIT_LEN;
+
+ /* scratch buffer to hold the userspace args */
+ buf_head = kmalloc(MAX_EXECVE_AUDIT_LEN + 1, GFP_KERNEL);
+ if (!buf_head) {
+ audit_panic("out of memory for argv string");
+ return;
}
+ buf = buf_head;
- /* walk the whole argument looking for non-ascii chars */
+ audit_log_format(*ab, "argc=%d", context->execve.argc);
+
+ len_rem = len_max;
+ len_buf = 0;
+ len_full = 0;
+ require_data = true;
+ encode = false;
+ iter = 0;
+ arg = 0;
do {
- if (len_left > MAX_EXECVE_AUDIT_LEN)
- to_send = MAX_EXECVE_AUDIT_LEN;
- else
- to_send = len_left;
- ret = copy_from_user(buf, tmp_p, to_send);
- /*
- * There is no reason for this copy to be short. We just
- * copied them here, and the mm hasn't been exposed to user-
- * space yet.
- */
- if (ret) {
- WARN_ON(1);
- send_sig(SIGKILL, current, 0);
- return -1;
- }
- buf[to_send] = '\0';
- has_cntl = audit_string_contains_control(buf, to_send);
- if (has_cntl) {
- /*
- * hex messages get logged as 2 bytes, so we can only
- * send half as much in each message
- */
- max_execve_audit_len = MAX_EXECVE_AUDIT_LEN / 2;
- break;
- }
- len_left -= to_send;
- tmp_p += to_send;
- } while (len_left > 0);
-
- len_left = len;
-
- if (len > max_execve_audit_len)
- too_long = 1;
-
- /* rewalk the argument actually logging the message */
- for (i = 0; len_left > 0; i++) {
- int room_left;
-
- if (len_left > max_execve_audit_len)
- to_send = max_execve_audit_len;
- else
- to_send = len_left;
-
- /* do we have space left to send this argument in this ab? */
- room_left = MAX_EXECVE_AUDIT_LEN - arg_num_len - *len_sent;
- if (has_cntl)
- room_left -= (to_send * 2);
- else
- room_left -= to_send;
- if (room_left < 0) {
- *len_sent = 0;
- audit_log_end(*ab);
- *ab = audit_log_start(context, GFP_KERNEL, AUDIT_EXECVE);
- if (!*ab)
- return 0;
- }
+ /* NOTE: we don't ever want to trust this value for anything
+ * serious, but the audit record format insists we
+ * provide an argument length for really long arguments,
+ * e.g. > MAX_EXECVE_AUDIT_LEN, so we have no choice but
+ * to use strncpy_from_user() to obtain this value for
+ * recording in the log, although we don't use it
+ * anywhere here to avoid a double-fetch problem */
+ if (len_full == 0)
+ len_full = strnlen_user(p, MAX_ARG_STRLEN) - 1;
+
+ /* read more data from userspace */
+ if (require_data) {
+ /* can we make more room in the buffer? */
+ if (buf != buf_head) {
+ memmove(buf_head, buf, len_buf);
+ buf = buf_head;
+ }
+
+ /* fetch as much as we can of the argument */
+ len_tmp = strncpy_from_user(&buf_head[len_buf], p,
+ len_max - len_buf);
+ if (len_tmp == -EFAULT) {
+ /* unable to copy from userspace */
+ send_sig(SIGKILL, current, 0);
+ goto out;
+ } else if (len_tmp == (len_max - len_buf)) {
+ /* buffer is not large enough */
+ require_data = true;
+ /* NOTE: if we are going to span multiple
+ * buffers force the encoding so we stand
+ * a chance at a sane len_full value and
+ * consistent record encoding */
+ encode = true;
+ len_full = len_full * 2;
+ p += len_tmp;
+ } else {
+ require_data = false;
+ if (!encode)
+ encode = audit_string_contains_control(
+ buf, len_tmp);
+ /* try to use a trusted value for len_full */
+ if (len_full < len_max)
+ len_full = (encode ?
+ len_tmp * 2 : len_tmp);
+ p += len_tmp + 1;
+ }
+ len_buf += len_tmp;
+ buf_head[len_buf] = '\0';
- /*
- * first record needs to say how long the original string was
- * so we can be sure nothing was lost.
- */
- if ((i == 0) && (too_long))
- audit_log_format(*ab, " a%d_len=%zu", arg_num,
- has_cntl ? 2*len : len);
-
- /*
- * normally arguments are small enough to fit and we already
- * filled buf above when we checked for control characters
- * so don't bother with another copy_from_user
- */
- if (len >= max_execve_audit_len)
- ret = copy_from_user(buf, p, to_send);
- else
- ret = 0;
- if (ret) {
- WARN_ON(1);
- send_sig(SIGKILL, current, 0);
- return -1;
+ /* length of the buffer in the audit record? */
+ len_abuf = (encode ? len_buf * 2 : len_buf + 2);
}
- buf[to_send] = '\0';
-
- /* actually log it */
- audit_log_format(*ab, " a%d", arg_num);
- if (too_long)
- audit_log_format(*ab, "[%d]", i);
- audit_log_format(*ab, "=");
- if (has_cntl)
- audit_log_n_hex(*ab, buf, to_send);
- else
- audit_log_string(*ab, buf);
-
- p += to_send;
- len_left -= to_send;
- *len_sent += arg_num_len;
- if (has_cntl)
- *len_sent += to_send * 2;
- else
- *len_sent += to_send;
- }
- /* include the null we didn't log */
- return len + 1;
-}
-static void audit_log_execve_info(struct audit_context *context,
- struct audit_buffer **ab)
-{
- int i, len;
- size_t len_sent = 0;
- const char __user *p;
- char *buf;
+ /* write as much as we can to the audit log */
+ if (len_buf > 0) {
+ /* NOTE: some magic numbers here - basically if we
+ * can't fit a reasonable amount of data into the
+ * existing audit buffer, flush it and start with
+ * a new buffer */
+ if ((sizeof(abuf) + 8) > len_rem) {
+ len_rem = len_max;
+ audit_log_end(*ab);
+ *ab = audit_log_start(context,
+ GFP_KERNEL, AUDIT_EXECVE);
+ if (!*ab)
+ goto out;
+ }
- p = (const char __user *)current->mm->arg_start;
+ /* create the non-arg portion of the arg record */
+ len_tmp = 0;
+ if (require_data || (iter > 0) ||
+ ((len_abuf + sizeof(abuf)) > len_rem)) {
+ if (iter == 0) {
+ len_tmp += snprintf(&abuf[len_tmp],
+ sizeof(abuf) - len_tmp,
+ " a%d_len=%lu",
+ arg, len_full);
+ }
+ len_tmp += snprintf(&abuf[len_tmp],
+ sizeof(abuf) - len_tmp,
+ " a%d[%d]=", arg, iter++);
+ } else
+ len_tmp += snprintf(&abuf[len_tmp],
+ sizeof(abuf) - len_tmp,
+ " a%d=", arg);
+ WARN_ON(len_tmp >= sizeof(abuf));
+ abuf[sizeof(abuf) - 1] = '\0';
+
+ /* log the arg in the audit record */
+ audit_log_format(*ab, "%s", abuf);
+ len_rem -= len_tmp;
+ len_tmp = len_buf;
+ if (encode) {
+ if (len_abuf > len_rem)
+ len_tmp = len_rem / 2; /* encoding */
+ audit_log_n_hex(*ab, buf, len_tmp);
+ len_rem -= len_tmp * 2;
+ len_abuf -= len_tmp * 2;
+ } else {
+ if (len_abuf > len_rem)
+ len_tmp = len_rem - 2; /* quotes */
+ audit_log_n_string(*ab, buf, len_tmp);
+ len_rem -= len_tmp + 2;
+ /* don't subtract the "2" because we still need
+ * to add quotes to the remaining string */
+ len_abuf -= len_tmp;
+ }
+ len_buf -= len_tmp;
+ buf += len_tmp;
+ }
- audit_log_format(*ab, "argc=%d", context->execve.argc);
+ /* ready to move to the next argument? */
+ if ((len_buf == 0) && !require_data) {
+ arg++;
+ iter = 0;
+ len_full = 0;
+ require_data = true;
+ encode = false;
+ }
+ } while (arg < context->execve.argc);
- /*
- * we need some kernel buffer to hold the userspace args. Just
- * allocate one big one rather than allocating one of the right size
- * for every single argument inside audit_log_single_execve_arg()
- * should be <8k allocation so should be pretty safe.
- */
- buf = kmalloc(MAX_EXECVE_AUDIT_LEN + 1, GFP_KERNEL);
- if (!buf) {
- audit_panic("out of memory for argv string");
- return;
- }
+ /* NOTE: the caller handles the final audit_log_end() call */
- for (i = 0; i < context->execve.argc; i++) {
- len = audit_log_single_execve_arg(context, ab, i,
- &len_sent, p, buf);
- if (len <= 0)
- break;
- p += len;
- }
- kfree(buf);
+out:
+ kfree(buf_head);
}
static void show_special(struct audit_context *context, int *call_panic)
@@ -1425,7 +1425,7 @@ static void audit_log_exit(struct audit_context *context, struct task_struct *ts
if (context->pwd.dentry && context->pwd.mnt) {
ab = audit_log_start(context, GFP_KERNEL, AUDIT_CWD);
if (ab) {
- audit_log_d_path(ab, " cwd=", &context->pwd);
+ audit_log_d_path(ab, "cwd=", &context->pwd);
audit_log_end(ab);
}
}