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Date: Thu, 31 Jul 2014 15:49:55 -0700
From: Casey Schaufler <casey@...aufler-ca.com>
To: Paul Moore <pmoore@...hat.com>, netdev@...r.kernel.org,
linux-security-module@...r.kernel.org, selinux@...ho.nsa.gov
CC: Christian Evans <frodox@...o.com>,
Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: [PATCH 3/4] netlabel: fix the catmap walking functions
On 7/31/2014 2:44 PM, Paul Moore wrote:
> The two NetLabel LSM secattr catmap walk functions didn't handle
> certain edge conditions correctly, causing incorrect security labels
> to be generated in some cases. This patch corrects these problems and
> converts the functions to use the new _netlbl_secattr_catmap_getnode()
> function in order to reduce the amount of repeated code.
>
> Cc: stable@...r.kernel.org
> Signed-off-by: Paul Moore <pmoore@...hat.com>
Tested-by: Casey Schaufler <casey@...aufler-ca.com>
> ---
> net/netlabel/netlabel_kapi.c | 102 ++++++++++++++++++++++--------------------
> 1 file changed, 54 insertions(+), 48 deletions(-)
>
> diff --git a/net/netlabel/netlabel_kapi.c b/net/netlabel/netlabel_kapi.c
> index d9e1046..bc38838 100644
> --- a/net/netlabel/netlabel_kapi.c
> +++ b/net/netlabel/netlabel_kapi.c
> @@ -407,6 +407,7 @@ out_entry:
>
> #define _CM_F_NONE 0x00000000
> #define _CM_F_ALLOC 0x00000001
> +#define _CM_F_WALK 0x00000002
>
> /**
> * _netlbl_secattr_catmap_getnode - Get a individual node from a catmap
> @@ -416,10 +417,11 @@ out_entry:
> * @gfp_flags: memory allocation flags
> *
> * Description:
> - * Iterate through the catmap looking for the node associated with @offset; if
> - * the _CM_F_ALLOC flag is set in @cm_flags and there is no associated node,
> - * one will be created and inserted into the catmap. Returns a pointer to the
> - * node on success, NULL on failure.
> + * Iterate through the catmap looking for the node associated with @offset.
> + * If the _CM_F_ALLOC flag is set in @cm_flags and there is no associated node,
> + * one will be created and inserted into the catmap. If the _CM_F_WALK flag is
> + * set in @cm_flags and there is no associated node, the next highest node will
> + * be returned. Returns a pointer to the node on success, NULL on failure.
> *
> */
> static struct netlbl_lsm_secattr_catmap *_netlbl_secattr_catmap_getnode(
> @@ -431,17 +433,22 @@ static struct netlbl_lsm_secattr_catmap *_netlbl_secattr_catmap_getnode(
> struct netlbl_lsm_secattr_catmap *iter = *catmap;
> struct netlbl_lsm_secattr_catmap *prev = NULL;
>
> - if (iter == NULL || offset < iter->startbit)
> + if (iter == NULL)
> goto secattr_catmap_getnode_alloc;
> + if (offset < iter->startbit)
> + goto secattr_catmap_getnode_walk;
> while (iter && offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
> prev = iter;
> iter = iter->next;
> }
> if (iter == NULL || offset < iter->startbit)
> - goto secattr_catmap_getnode_alloc;
> + goto secattr_catmap_getnode_walk;
>
> return iter;
>
> +secattr_catmap_getnode_walk:
> + if (cm_flags & _CM_F_WALK)
> + return iter;
> secattr_catmap_getnode_alloc:
> if (!(cm_flags & _CM_F_ALLOC))
> return NULL;
> @@ -476,43 +483,41 @@ int netlbl_secattr_catmap_walk(struct netlbl_lsm_secattr_catmap *catmap,
> u32 offset)
> {
> struct netlbl_lsm_secattr_catmap *iter = catmap;
> - u32 node_idx;
> - u32 node_bit;
> + u32 idx;
> + u32 bit;
> NETLBL_CATMAP_MAPTYPE bitmap;
>
> + iter = _netlbl_secattr_catmap_getnode(&catmap, offset, _CM_F_WALK, 0);
> + if (iter == NULL)
> + return -ENOENT;
> if (offset > iter->startbit) {
> - while (offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
> - iter = iter->next;
> - if (iter == NULL)
> - return -ENOENT;
> - }
> - node_idx = (offset - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
> - node_bit = offset - iter->startbit -
> - (NETLBL_CATMAP_MAPSIZE * node_idx);
> + offset -= iter->startbit;
> + idx = offset / NETLBL_CATMAP_MAPSIZE;
> + bit = offset % NETLBL_CATMAP_MAPSIZE;
> } else {
> - node_idx = 0;
> - node_bit = 0;
> + idx = 0;
> + bit = 0;
> }
> - bitmap = iter->bitmap[node_idx] >> node_bit;
> + bitmap = iter->bitmap[idx] >> bit;
>
> for (;;) {
> if (bitmap != 0) {
> while ((bitmap & NETLBL_CATMAP_BIT) == 0) {
> bitmap >>= 1;
> - node_bit++;
> + bit++;
> }
> return iter->startbit +
> - (NETLBL_CATMAP_MAPSIZE * node_idx) + node_bit;
> + (NETLBL_CATMAP_MAPSIZE * idx) + bit;
> }
> - if (++node_idx >= NETLBL_CATMAP_MAPCNT) {
> + if (++idx >= NETLBL_CATMAP_MAPCNT) {
> if (iter->next != NULL) {
> iter = iter->next;
> - node_idx = 0;
> + idx = 0;
> } else
> return -ENOENT;
> }
> - bitmap = iter->bitmap[node_idx];
> - node_bit = 0;
> + bitmap = iter->bitmap[idx];
> + bit = 0;
> }
>
> return -ENOENT;
> @@ -532,46 +537,47 @@ int netlbl_secattr_catmap_walk(struct netlbl_lsm_secattr_catmap *catmap,
> int netlbl_secattr_catmap_walk_rng(struct netlbl_lsm_secattr_catmap *catmap,
> u32 offset)
> {
> - struct netlbl_lsm_secattr_catmap *iter = catmap;
> - u32 node_idx;
> - u32 node_bit;
> + struct netlbl_lsm_secattr_catmap *iter;
> + struct netlbl_lsm_secattr_catmap *prev = NULL;
> + u32 idx;
> + u32 bit;
> NETLBL_CATMAP_MAPTYPE bitmask;
> NETLBL_CATMAP_MAPTYPE bitmap;
>
> + iter = _netlbl_secattr_catmap_getnode(&catmap, offset, _CM_F_WALK, 0);
> + if (iter == NULL)
> + return -ENOENT;
> if (offset > iter->startbit) {
> - while (offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
> - iter = iter->next;
> - if (iter == NULL)
> - return -ENOENT;
> - }
> - node_idx = (offset - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
> - node_bit = offset - iter->startbit -
> - (NETLBL_CATMAP_MAPSIZE * node_idx);
> + offset -= iter->startbit;
> + idx = offset / NETLBL_CATMAP_MAPSIZE;
> + bit = offset % NETLBL_CATMAP_MAPSIZE;
> } else {
> - node_idx = 0;
> - node_bit = 0;
> + idx = 0;
> + bit = 0;
> }
> - bitmask = NETLBL_CATMAP_BIT << node_bit;
> + bitmask = NETLBL_CATMAP_BIT << bit;
>
> for (;;) {
> - bitmap = iter->bitmap[node_idx];
> + bitmap = iter->bitmap[idx];
> while (bitmask != 0 && (bitmap & bitmask) != 0) {
> bitmask <<= 1;
> - node_bit++;
> + bit++;
> }
>
> - if (bitmask != 0)
> + if (prev && idx == 0 && bit == 0)
> + return prev->startbit + NETLBL_CATMAP_SIZE - 1;
> + else if (bitmask != 0)
> return iter->startbit +
> - (NETLBL_CATMAP_MAPSIZE * node_idx) +
> - node_bit - 1;
> - else if (++node_idx >= NETLBL_CATMAP_MAPCNT) {
> + (NETLBL_CATMAP_MAPSIZE * idx) + bit - 1;
> + else if (++idx >= NETLBL_CATMAP_MAPCNT) {
> if (iter->next == NULL)
> - return iter->startbit + NETLBL_CATMAP_SIZE - 1;
> + return iter->startbit + NETLBL_CATMAP_SIZE - 1;
> + prev = iter;
> iter = iter->next;
> - node_idx = 0;
> + idx = 0;
> }
> bitmask = NETLBL_CATMAP_BIT;
> - node_bit = 0;
> + bit = 0;
> }
>
> return -ENOENT;
>
> --
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