[PATCH] log more info for directory entry change events

When an audit event involves changes to a directory entry, include
a PATH record for the directory itself.  A few other notable changes:

    - fixed audit_inode_child() hooks in fsnotify_move()
    - removed unused flags arg from audit_inode()
    - added audit log routines for logging a portion of a string

Here's some sample output.

before patch:
type=SYSCALL msg=audit(1149821605.320:26): arch=40000003 syscall=39 success=yes exit=0 a0=bf8d3c7c a1=1ff a2=804e1b8 a3=bf8d3c7c items=1 ppid=739 pid=800 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=ttyS0 comm="mkdir" exe="/bin/mkdir" subj=root:system_r:unconfined_t:s0-s0:c0.c255
type=CWD msg=audit(1149821605.320:26):  cwd="/root"
type=PATH msg=audit(1149821605.320:26): item=0 name="foo" parent=164068 inode=164010 dev=03:00 mode=040755 ouid=0 ogid=0 rdev=00:00 obj=root:object_r:user_home_t:s0

after patch:
type=SYSCALL msg=audit(1149822032.332:24): arch=40000003 syscall=39 success=yes exit=0 a0=bfdd9c7c a1=1ff a2=804e1b8 a3=bfdd9c7c items=2 ppid=714 pid=777 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=ttyS0 comm="mkdir" exe="/bin/mkdir" subj=root:system_r:unconfined_t:s0-s0:c0.c255
type=CWD msg=audit(1149822032.332:24):  cwd="/root"
type=PATH msg=audit(1149822032.332:24): item=0 name="/root" inode=164068 dev=03:00 mode=040750 ouid=0 ogid=0 rdev=00:00 obj=root:object_r:user_home_dir_t:s0
type=PATH msg=audit(1149822032.332:24): item=1 name="foo" inode=164010 dev=03:00 mode=040755 ouid=0 ogid=0 rdev=00:00 obj=root:object_r:user_home_t:s0

Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 50 insertions, 4 deletions

diff --git a/kernel/audit.c b/kernel/audit.c
index 0fbf1c116363..7dfac7031bd7 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1051,20 +1051,53 @@ void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf,
         skb_put(skb, len << 1); /* new string is twice the old string */
 }
 
+/*
+ * Format a string of no more than slen characters into the audit buffer,
+ * enclosed in quote marks.
+ */
+static void audit_log_n_string(struct audit_buffer *ab, size_t slen,
+                               const char *string)
+{
+        int avail, new_len;
+        unsigned char *ptr;
+        struct sk_buff *skb;
+
+        BUG_ON(!ab->skb);
+        skb = ab->skb;
+        avail = skb_tailroom(skb);
+        new_len = slen + 3;     /* enclosing quotes + null terminator */
+        if (new_len > avail) {
+                avail = audit_expand(ab, new_len);
+                if (!avail)
+                        return;
+        }
+        ptr = skb->tail;
+        *ptr++ = '"';
+        memcpy(ptr, string, slen);
+        ptr += slen;
+        *ptr++ = '"';
+        *ptr = 0;
+        skb_put(skb, slen + 2); /* don't include null terminator */
+}
+
 /**
- * audit_log_unstrustedstring - log a string that may contain random characters
+ * audit_log_n_unstrustedstring - log a string that may contain random characters
  * @ab: audit_buffer
+ * @len: lenth of string (not including trailing null)
  * @string: string to be logged
  *
  * This code will escape a string that is passed to it if the string
  * contains a control character, unprintable character, double quote mark,
  * or a space. Unescaped strings will start and end with a double quote mark.
  * Strings that are escaped are printed in hex (2 digits per char).
+ *
+ * The caller specifies the number of characters in the string to log, which may
+ * or may not be the entire string.
  */
-const char *audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
+const char *audit_log_n_untrustedstring(struct audit_buffer *ab, size_t len,
+                                        const char *string)
 {
         const unsigned char *p = string;
-        size_t len = strlen(string);
 
         while (*p) {
                 if (*p == '"' || *p < 0x21 || *p > 0x7f) {
@@ -1073,10 +1106,23 @@ const char *audit_log_untrustedstring(struct audit_buffer *ab, const char *strin
                 }
                 p++;
         }
-        audit_log_format(ab, "\"%s\"", string);
+        audit_log_n_string(ab, len, string);
         return p + 1;
 }
 
+/**
+ * audit_log_unstrustedstring - log a string that may contain random characters
+ * @ab: audit_buffer
+ * @string: string to be logged
+ *
+ * Same as audit_log_n_unstrustedstring(), except that strlen is used to
+ * determine string length.
+ */
+const char *audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
+{
+        return audit_log_n_untrustedstring(ab, strlen(string), string);
+}
+
 /* This is a helper-function to print the escaped d_path */
 void audit_log_d_path(struct audit_buffer *ab, const char *prefix,
                       struct dentry *dentry, struct vfsmount *vfsmnt)