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AUDIT: Avoid log pollution by untrusted strings.

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We log strings from userspace, such as arguments to open(). These could
be formatted to contain \n followed by fake audit log entries. Provide
a function for logging such strings, which gives a hex dump when the
string contains anything but basic printable ASCII characters. Use it
for logging filenames.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
This commit is contained in:
2005-04-29 15:54:44 +01:00
parent c60c390620
commit 83c7d09173
3 changed files with 34 additions and 4 deletions
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8
include/linux/audit.h
View file

@ -174,11 +174,15 @@ extern void audit_log_format(struct audit_buffer *ab,
const char *fmt, ...)
__attribute__((format(printf,2,3)));
extern void audit_log_end(struct audit_buffer *ab);
extern void audit_log_hex(struct audit_buffer *ab,
const unsigned char *buf,
size_t len);
extern void audit_log_untrustedstring(struct audit_buffer *ab,
const char *string);
extern void audit_log_d_path(struct audit_buffer *ab,
const char *prefix,
struct dentry *dentry,
struct vfsmount *vfsmnt);
/* Private API (for auditsc.c only) */
extern void audit_send_reply(int pid, int seq, int type,
int done, int multi,
@ -190,6 +194,8 @@ extern void audit_log_lost(const char *message);
#define audit_log_vformat(b,f,a) do { ; } while (0)
#define audit_log_format(b,f,...) do { ; } while (0)
#define audit_log_end(b) do { ; } while (0)
#define audit_log_hex(a,b,l) do { ; } while (0)
#define audit_log_untrustedstring(a,s) do { ; } while (0)
#define audit_log_d_path(b,p,d,v) do { ; } while (0)
#endif
#endif

23
kernel/audit.c
View file

@ -720,6 +720,29 @@ void audit_log_format(struct audit_buffer *ab, const char *fmt, ...)
va_end(args);
}
void audit_log_hex(struct audit_buffer *ab, const unsigned char *buf, size_t len)
{
int i;
for (i=0; i<len; i++)
audit_log_format(ab, "%02x", buf[i]);
}
void audit_log_untrustedstring(struct audit_buffer *ab, const char *string)
{
const char *p = string;
while (*p) {
if (*p == '"' || *p == ' ' || *p < 0x20 || *p > 0x7f) {
audit_log_hex(ab, string, strlen(string));
return;
}
p++;
}
audit_log_format(ab, "\"%s\"", string);
}
/* This is a helper-function to print the d_path without using a static
* buffer or allocating another buffer in addition to the one in
* audit_buffer. */

7
kernel/auditsc.c
View file

@ -696,9 +696,10 @@ static void audit_log_exit(struct audit_context *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].name) {
audit_log_format(ab, " name=");
audit_log_untrustedstring(ab, 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",