Commit 7f3ebcf2 authored by Tyler Hicks's avatar Tyler Hicks Committed by John Johansen
Browse files

apparmor: Check buffer bounds when mapping permissions mask 



Don't read past the end of the buffer containing permissions
characters or write past the end of the destination string.

Detected by CoverityScan CID#1415361, 1415376 ("Out-of-bounds access")

Fixes: e53cfe6c ("apparmor: rework perm mapping to a slightly broader set")
Signed-off-by: default avatarTyler Hicks <tyhicks@canonical.com>
Acked-by: default avatarSerge Hallyn <serge@hallyn.com>
Signed-off-by: default avatarJohn Johansen <john.johansen@canonical.com>
parent fb7d1bcf

security/apparmor/file.c

+2 −1
Original line number Diff line number Diff line
@@ -47,7 +47,8 @@ static void audit_file_mask(struct audit_buffer *ab, u32 mask) 
{

	char str[10];



	aa_perm_mask_to_str(str, aa_file_perm_chrs, map_mask_to_chr_mask(mask));

	aa_perm_mask_to_str(str, sizeof(str), aa_file_perm_chrs,

			    map_mask_to_chr_mask(mask));

	audit_log_string(ab, str);

}

security/apparmor/include/perms.h

+2 −1
Original line number Diff line number Diff line
@@ -137,7 +137,8 @@ extern struct aa_perms allperms; 
	xcheck(fn_for_each((L1), (P), (FN1)), fn_for_each((L2), (P), (FN2)))





void aa_perm_mask_to_str(char *str, const char *chrs, u32 mask);

void aa_perm_mask_to_str(char *str, size_t str_size, const char *chrs,

			 u32 mask);

void aa_audit_perm_names(struct audit_buffer *ab, const char * const *names,

			 u32 mask);

void aa_audit_perm_mask(struct audit_buffer *ab, u32 mask, const char *chrs,

security/apparmor/lib.c

+13 −4
Original line number Diff line number Diff line
@@ -198,15 +198,24 @@ const char *aa_file_perm_names[] = { 
/**

 * aa_perm_mask_to_str - convert a perm mask to its short string

 * @str: character buffer to store string in (at least 10 characters)

 * @str_size: size of the @str buffer

 * @chrs: NUL-terminated character buffer of permission characters

 * @mask: permission mask to convert

 */

void aa_perm_mask_to_str(char *str, const char *chrs, u32 mask)

void aa_perm_mask_to_str(char *str, size_t str_size, const char *chrs, u32 mask)

{

	unsigned int i, perm = 1;

	size_t num_chrs = strlen(chrs);



	for (i = 0; i < num_chrs; perm <<= 1, i++) {

		if (mask & perm) {

			/* Ensure that one byte is left for NUL-termination */

			if (WARN_ON_ONCE(str_size <= 1))

				break;



	for (i = 0; i < 32; perm <<= 1, i++) {

		if (mask & perm)

			*str++ = chrs[i];

			str_size--;

		}

	}

	*str = '\0';

}
@@ -236,7 +245,7 @@ void aa_audit_perm_mask(struct audit_buffer *ab, u32 mask, const char *chrs, 


	audit_log_format(ab, "\"");

	if ((mask & chrsmask) && chrs) {

		aa_perm_mask_to_str(str, chrs, mask & chrsmask);

		aa_perm_mask_to_str(str, sizeof(str), chrs, mask & chrsmask);

		mask &= ~chrsmask;

		audit_log_format(ab, "%s", str);

		if (mask & namesmask)

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