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-rw-r--r--lib/vsprintf.c35
1 files changed, 32 insertions, 3 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 26559bdb4c49..48586ac3a62e 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -27,6 +27,7 @@
#include <linux/uaccess.h>
#include <linux/ioport.h>
#include <linux/dcache.h>
+#include <linux/cred.h>
#include <net/addrconf.h>
#include <asm/page.h> /* for PAGE_SIZE */
@@ -1218,6 +1219,8 @@ int kptr_restrict __read_mostly;
* The maximum supported length is 64 bytes of the input. Consider
* to use print_hex_dump() for the larger input.
* - 'a' For a phys_addr_t type and its derivative types (passed by reference)
+ * - 'd[234]' For a dentry name (optionally 2-4 last components)
+ * - 'D[234]' Same as 'd' but for a struct file
*
* Note: The difference between 'S' and 'F' is that on ia64 and ppc64
* function pointers are really function descriptors, which contain a
@@ -1312,11 +1315,37 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
spec.field_width = default_width;
return string(buf, end, "pK-error", spec);
}
- if (!((kptr_restrict == 0) ||
- (kptr_restrict == 1 &&
- has_capability_noaudit(current, CAP_SYSLOG))))
+
+ switch (kptr_restrict) {
+ case 0:
+ /* Always print %pK values */
+ break;
+ case 1: {
+ /*
+ * Only print the real pointer value if the current
+ * process has CAP_SYSLOG and is running with the
+ * same credentials it started with. This is because
+ * access to files is checked at open() time, but %pK
+ * checks permission at read() time. We don't want to
+ * leak pointer values if a binary opens a file using
+ * %pK and then elevates privileges before reading it.
+ */
+ const struct cred *cred = current_cred();
+
+ if (!has_capability_noaudit(current, CAP_SYSLOG) ||
+ !uid_eq(cred->euid, cred->uid) ||
+ !gid_eq(cred->egid, cred->gid))
+ ptr = NULL;
+ break;
+ }
+ case 2:
+ default:
+ /* Always print 0's for %pK */
ptr = NULL;
+ break;
+ }
break;
+
case 'N':
switch (fmt[1]) {
case 'F':