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-rw-r--r--fs/binfmt_misc.c136
1 files changed, 121 insertions, 15 deletions
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index 1cc5377ba955..d87ddc7c4b14 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -16,6 +16,8 @@
* 2001-02-28 AV: rewritten into something that resembles C. Original didn't.
*/
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
@@ -30,8 +32,13 @@
#include <linux/mount.h>
#include <linux/syscalls.h>
#include <linux/fs.h>
+#include <linux/uaccess.h>
-#include <asm/uaccess.h>
+#ifdef DEBUG
+# define USE_DEBUG 1
+#else
+# define USE_DEBUG 0
+#endif
enum {
VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
@@ -87,20 +94,24 @@ static Node *check_file(struct linux_binprm *bprm)
char *p = strrchr(bprm->interp, '.');
struct list_head *l;
+ /* Walk all the registered handlers. */
list_for_each(l, &entries) {
Node *e = list_entry(l, Node, list);
char *s;
int j;
+ /* Make sure this one is currently enabled. */
if (!test_bit(Enabled, &e->flags))
continue;
+ /* Do matching based on extension if applicable. */
if (!test_bit(Magic, &e->flags)) {
if (p && !strcmp(e->magic, p + 1))
return e;
continue;
}
+ /* Do matching based on magic & mask. */
s = bprm->buf + e->offset;
if (e->mask) {
for (j = 0; j < e->size; j++)
@@ -259,14 +270,17 @@ static char * check_special_flags (char * sfs, Node * e)
while (cont) {
switch (*p) {
case 'P':
+ pr_debug("register: flag: P (preserve argv0)\n");
p++;
e->flags |= MISC_FMT_PRESERVE_ARGV0;
break;
case 'O':
+ pr_debug("register: flag: O (open binary)\n");
p++;
e->flags |= MISC_FMT_OPEN_BINARY;
break;
case 'C':
+ pr_debug("register: flag: C (preserve creds)\n");
p++;
/* this flags also implies the
open-binary flag */
@@ -292,6 +306,8 @@ static Node *create_entry(const char __user *buffer, size_t count)
char *buf, *p;
char del;
+ pr_debug("register: received %zu bytes\n", count);
+
/* some sanity checks */
err = -EINVAL;
if ((count < 11) || (count > MAX_REGISTER_LENGTH))
@@ -311,8 +327,12 @@ static Node *create_entry(const char __user *buffer, size_t count)
del = *p++; /* delimeter */
+ pr_debug("register: delim: %#x {%c}\n", del, del);
+
+ /* Pad the buffer with the delim to simplify parsing below. */
memset(buf+count, del, 8);
+ /* Parse the 'name' field. */
e->name = p;
p = strchr(p, del);
if (!p)
@@ -323,46 +343,113 @@ static Node *create_entry(const char __user *buffer, size_t count)
!strcmp(e->name, "..") ||
strchr(e->name, '/'))
goto Einval;
+
+ pr_debug("register: name: {%s}\n", e->name);
+
+ /* Parse the 'type' field. */
switch (*p++) {
- case 'E': e->flags = 1<<Enabled; break;
- case 'M': e->flags = (1<<Enabled) | (1<<Magic); break;
- default: goto Einval;
+ case 'E':
+ pr_debug("register: type: E (extension)\n");
+ e->flags = 1 << Enabled;
+ break;
+ case 'M':
+ pr_debug("register: type: M (magic)\n");
+ e->flags = (1 << Enabled) | (1 << Magic);
+ break;
+ default:
+ goto Einval;
}
if (*p++ != del)
goto Einval;
+
if (test_bit(Magic, &e->flags)) {
- char *s = strchr(p, del);
+ /* Handle the 'M' (magic) format. */
+ char *s;
+
+ /* Parse the 'offset' field. */
+ s = strchr(p, del);
if (!s)
goto Einval;
*s++ = '\0';
e->offset = simple_strtoul(p, &p, 10);
if (*p++)
goto Einval;
+ pr_debug("register: offset: %#x\n", e->offset);
+
+ /* Parse the 'magic' field. */
e->magic = p;
p = scanarg(p, del);
if (!p)
goto Einval;
p[-1] = '\0';
- if (!e->magic[0])
+ if (p == e->magic)
goto Einval;
+ if (USE_DEBUG)
+ print_hex_dump_bytes(
+ KBUILD_MODNAME ": register: magic[raw]: ",
+ DUMP_PREFIX_NONE, e->magic, p - e->magic);
+
+ /* Parse the 'mask' field. */
e->mask = p;
p = scanarg(p, del);
if (!p)
goto Einval;
p[-1] = '\0';
- if (!e->mask[0])
+ if (p == e->mask) {
e->mask = NULL;
+ pr_debug("register: mask[raw]: none\n");
+ } else if (USE_DEBUG)
+ print_hex_dump_bytes(
+ KBUILD_MODNAME ": register: mask[raw]: ",
+ DUMP_PREFIX_NONE, e->mask, p - e->mask);
+
+ /*
+ * Decode the magic & mask fields.
+ * Note: while we might have accepted embedded NUL bytes from
+ * above, the unescape helpers here will stop at the first one
+ * it encounters.
+ */
e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX);
if (e->mask &&
string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size)
goto Einval;
if (e->size + e->offset > BINPRM_BUF_SIZE)
goto Einval;
+ pr_debug("register: magic/mask length: %i\n", e->size);
+ if (USE_DEBUG) {
+ print_hex_dump_bytes(
+ KBUILD_MODNAME ": register: magic[decoded]: ",
+ DUMP_PREFIX_NONE, e->magic, e->size);
+
+ if (e->mask) {
+ int i;
+ char *masked = kmalloc(e->size, GFP_USER);
+
+ print_hex_dump_bytes(
+ KBUILD_MODNAME ": register: mask[decoded]: ",
+ DUMP_PREFIX_NONE, e->mask, e->size);
+
+ if (masked) {
+ for (i = 0; i < e->size; ++i)
+ masked[i] = e->magic[i] & e->mask[i];
+ print_hex_dump_bytes(
+ KBUILD_MODNAME ": register: magic[masked]: ",
+ DUMP_PREFIX_NONE, masked, e->size);
+
+ kfree(masked);
+ }
+ }
+ }
} else {
+ /* Handle the 'E' (extension) format. */
+
+ /* Skip the 'offset' field. */
p = strchr(p, del);
if (!p)
goto Einval;
*p++ = '\0';
+
+ /* Parse the 'magic' field. */
e->magic = p;
p = strchr(p, del);
if (!p)
@@ -370,11 +457,16 @@ static Node *create_entry(const char __user *buffer, size_t count)
*p++ = '\0';
if (!e->magic[0] || strchr(e->magic, '/'))
goto Einval;
+ pr_debug("register: extension: {%s}\n", e->magic);
+
+ /* Skip the 'mask' field. */
p = strchr(p, del);
if (!p)
goto Einval;
*p++ = '\0';
}
+
+ /* Parse the 'interpreter' field. */
e->interpreter = p;
p = strchr(p, del);
if (!p)
@@ -382,10 +474,10 @@ static Node *create_entry(const char __user *buffer, size_t count)
*p++ = '\0';
if (!e->interpreter[0])
goto Einval;
+ pr_debug("register: interpreter: {%s}\n", e->interpreter);
-
+ /* Parse the 'flags' field. */
p = check_special_flags (p, e);
-
if (*p == '\n')
p++;
if (p != buf + count)
@@ -553,11 +645,17 @@ static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
int res = parse_command(buffer, count);
switch (res) {
- case 1: clear_bit(Enabled, &e->flags);
+ case 1:
+ /* Disable this handler. */
+ clear_bit(Enabled, &e->flags);
break;
- case 2: set_bit(Enabled, &e->flags);
+ case 2:
+ /* Enable this handler. */
+ set_bit(Enabled, &e->flags);
break;
- case 3: root = dget(file->f_path.dentry->d_sb->s_root);
+ case 3:
+ /* Delete this handler. */
+ root = dget(file->f_path.dentry->d_sb->s_root);
mutex_lock(&root->d_inode->i_mutex);
kill_node(e);
@@ -661,9 +759,17 @@ static ssize_t bm_status_write(struct file * file, const char __user * buffer,
struct dentry *root;
switch (res) {
- case 1: enabled = 0; break;
- case 2: enabled = 1; break;
- case 3: root = dget(file->f_path.dentry->d_sb->s_root);
+ case 1:
+ /* Disable all handlers. */
+ enabled = 0;
+ break;
+ case 2:
+ /* Enable all handlers. */
+ enabled = 1;
+ break;
+ case 3:
+ /* Delete all handlers. */
+ root = dget(file->f_path.dentry->d_sb->s_root);
mutex_lock(&root->d_inode->i_mutex);
while (!list_empty(&entries))
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.