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Commit 146a4606 authored by Michael Halcrow's avatar Michael Halcrow Committed by Linus Torvalds
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eCryptfs: fix Tag 11 writing code 



Fix up the Tag 11 writing code to handle size limits and boundaries more
explicitly.  It looks like the packet length was 1 shorter than it should have
been, chopping off the last byte of the key identifier.  This is largely
inconsequential, since it is not much more likely that a key identifier
collision will occur with 7 bytes rather than 8.  This patch fixes the packet
to use the full number of bytes that were originally intended to be used for
the key identifier.

Signed-off-by: default avatarMichael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f648104a

fs/ecryptfs/keystore.c

+22 −17
Original line number Diff line number Diff line
@@ -1449,47 +1449,52 @@ write_tag_1_packet(char *dest, size_t *remaining_bytes, 
 * Returns zero on success; non-zero on error.

 */

static int

write_tag_11_packet(char *dest, int max, char *contents, size_t contents_length,

		    size_t *packet_length)

write_tag_11_packet(char *dest, int *remaining_bytes, char *contents,

		    size_t contents_length, size_t *packet_length)

{

	size_t packet_size_length;

	size_t max_packet_size;

	int rc = 0;



	(*packet_length) = 0;

	if ((13 + contents_length) > max) {

	/* This format is inspired by OpenPGP; see RFC 2440

	 * packet tag 11 */

	max_packet_size = (1                   /* Tag 11 identifier */

			   + 3                 /* Max Tag 11 packet size */

			   + 1                 /* Binary format specifier */

			   + 1                 /* Filename length */

			   + 8                 /* Filename ("_CONSOLE") */

			   + 4                 /* Modification date */

			   + contents_length); /* Literal data */

	if (max_packet_size > (*remaining_bytes)) {

		printk(KERN_ERR "Packet length larger than maximum allowable; "

		       "need up to [%d] bytes, but there are only [%d] "

		       "available\n", max_packet_size, (*remaining_bytes));

		rc = -EINVAL;

		ecryptfs_printk(KERN_ERR, "Packet length larger than "

				"maximum allowable\n");

		goto out;

	}

	/* General packet header */

	/* Packet tag */

	dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;

	/* Packet length */

	rc = write_packet_length(&dest[(*packet_length)],

				 (13 + contents_length), &packet_size_length);

				 (max_packet_size - 4), &packet_size_length);

	if (rc) {

		ecryptfs_printk(KERN_ERR, "Error generating tag 11 packet "

				"header; cannot generate packet length\n");

		printk(KERN_ERR "Error generating tag 11 packet header; cannot "

		       "generate packet length. rc = [%d]\n", rc);

		goto out;

	}

	(*packet_length) += packet_size_length;

	/* Tag 11 specific */

	/* One-octet field that describes how the data is formatted */

	dest[(*packet_length)++] = 0x62; /* binary data */

	/* One-octet filename length followed by filename */

	dest[(*packet_length)++] = 0x62; /* binary data format specifier */

	dest[(*packet_length)++] = 8;

	memcpy(&dest[(*packet_length)], "_CONSOLE", 8);

	(*packet_length) += 8;

	/* Four-octet number indicating modification date */

	memset(&dest[(*packet_length)], 0x00, 4);

	(*packet_length) += 4;

	/* Remainder is literal data */

	memcpy(&dest[(*packet_length)], contents, contents_length);

	(*packet_length) += contents_length;

 out:

	if (rc)

		(*packet_length) = 0;

	else

		(*remaining_bytes) -= (*packet_length);

	return rc;

}