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Date: Thu, 31 Jul 2014 15:48:54 -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 1/4] netlabel: fix a problem when setting bits below the
previously lowest bit
On 7/31/2014 2:44 PM, Paul Moore wrote:
> The NetLabel category (catmap) functions have a problem in that they
> assume categories will be set in an increasing manner, e.g. the next
> category set will always be larger than the last. Unfortunately, this
> is not a valid assumption and could result in problems when attempting
> to set categories less than the startbit in the lowest catmap node.
> In some cases kernel panics and other nasties can result.
>
> This patch corrects the problem by checking for this and allocating a
> new catmap node instance and placing it at the front of the list.
>
> Cc: stable@...r.kernel.org
> Reported-by: Christian Evans <frodox@...o.com>
> Signed-off-by: Paul Moore <pmoore@...hat.com>
Tested-by: Casey Schaufler <casey@...aufler-ca.com>
> ---
> include/net/netlabel.h | 8 ++++----
> net/ipv4/cipso_ipv4.c | 6 +++---
> net/netlabel/netlabel_kapi.c | 26 ++++++++++++++++++--------
> security/smack/smack_access.c | 2 +-
> 4 files changed, 26 insertions(+), 16 deletions(-)
>
> diff --git a/include/net/netlabel.h b/include/net/netlabel.h
> index 4fe018c..1c40d65 100644
> --- a/include/net/netlabel.h
> +++ b/include/net/netlabel.h
> @@ -394,10 +394,10 @@ int netlbl_secattr_catmap_walk(struct netlbl_lsm_secattr_catmap *catmap,
> u32 offset);
> int netlbl_secattr_catmap_walk_rng(struct netlbl_lsm_secattr_catmap *catmap,
> u32 offset);
> -int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap *catmap,
> +int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap **catmap,
> u32 bit,
> gfp_t flags);
> -int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap *catmap,
> +int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap **catmap,
> u32 start,
> u32 end,
> gfp_t flags);
> @@ -505,14 +505,14 @@ static inline int netlbl_secattr_catmap_walk_rng(
> return -ENOENT;
> }
> static inline int netlbl_secattr_catmap_setbit(
> - struct netlbl_lsm_secattr_catmap *catmap,
> + struct netlbl_lsm_secattr_catmap **catmap,
> u32 bit,
> gfp_t flags)
> {
> return 0;
> }
> static inline int netlbl_secattr_catmap_setrng(
> - struct netlbl_lsm_secattr_catmap *catmap,
> + struct netlbl_lsm_secattr_catmap **catmap,
> u32 start,
> u32 end,
> gfp_t flags)
> diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
> index 69e77c8..dd433c9 100644
> --- a/net/ipv4/cipso_ipv4.c
> +++ b/net/ipv4/cipso_ipv4.c
> @@ -973,7 +973,7 @@ static int cipso_v4_map_cat_rbm_ntoh(const struct cipso_v4_doi *doi_def,
> return -EPERM;
> break;
> }
> - ret_val = netlbl_secattr_catmap_setbit(secattr->attr.mls.cat,
> + ret_val = netlbl_secattr_catmap_setbit(&secattr->attr.mls.cat,
> host_spot,
> GFP_ATOMIC);
> if (ret_val != 0)
> @@ -1075,7 +1075,7 @@ static int cipso_v4_map_cat_enum_ntoh(const struct cipso_v4_doi *doi_def,
> u32 iter;
>
> for (iter = 0; iter < net_cat_len; iter += 2) {
> - ret_val = netlbl_secattr_catmap_setbit(secattr->attr.mls.cat,
> + ret_val = netlbl_secattr_catmap_setbit(&secattr->attr.mls.cat,
> get_unaligned_be16(&net_cat[iter]),
> GFP_ATOMIC);
> if (ret_val != 0)
> @@ -1217,7 +1217,7 @@ static int cipso_v4_map_cat_rng_ntoh(const struct cipso_v4_doi *doi_def,
> else
> cat_low = 0;
>
> - ret_val = netlbl_secattr_catmap_setrng(secattr->attr.mls.cat,
> + ret_val = netlbl_secattr_catmap_setrng(&secattr->attr.mls.cat,
> cat_low,
> cat_high,
> GFP_ATOMIC);
> diff --git a/net/netlabel/netlabel_kapi.c b/net/netlabel/netlabel_kapi.c
> index 3045a96..84e810b 100644
> --- a/net/netlabel/netlabel_kapi.c
> +++ b/net/netlabel/netlabel_kapi.c
> @@ -522,7 +522,7 @@ int netlbl_secattr_catmap_walk_rng(struct netlbl_lsm_secattr_catmap *catmap,
>
> /**
> * netlbl_secattr_catmap_setbit - Set a bit in a LSM secattr catmap
> - * @catmap: the category bitmap
> + * @catmap: pointer to the category bitmap
> * @bit: the bit to set
> * @flags: memory allocation flags
> *
> @@ -531,18 +531,25 @@ int netlbl_secattr_catmap_walk_rng(struct netlbl_lsm_secattr_catmap *catmap,
> * negative values on failure.
> *
> */
> -int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap *catmap,
> +int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap **catmap,
> u32 bit,
> gfp_t flags)
> {
> - struct netlbl_lsm_secattr_catmap *iter = catmap;
> + struct netlbl_lsm_secattr_catmap *iter = *catmap;
> u32 node_bit;
> u32 node_idx;
>
> while (iter->next != NULL &&
> bit >= (iter->startbit + NETLBL_CATMAP_SIZE))
> iter = iter->next;
> - if (bit >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
> + if (bit < iter->startbit) {
> + iter = netlbl_secattr_catmap_alloc(flags);
> + if (iter == NULL)
> + return -ENOMEM;
> + iter->next = *catmap;
> + iter->startbit = bit & ~(NETLBL_CATMAP_SIZE - 1);
> + *catmap = iter;
> + } else if (bit >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
> iter->next = netlbl_secattr_catmap_alloc(flags);
> if (iter->next == NULL)
> return -ENOMEM;
> @@ -560,7 +567,7 @@ int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap *catmap,
>
> /**
> * netlbl_secattr_catmap_setrng - Set a range of bits in a LSM secattr catmap
> - * @catmap: the category bitmap
> + * @catmap: pointer to the category bitmap
> * @start: the starting bit
> * @end: the last bit in the string
> * @flags: memory allocation flags
> @@ -570,15 +577,16 @@ int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap *catmap,
> * on success, negative values on failure.
> *
> */
> -int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap *catmap,
> +int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap **catmap,
> u32 start,
> u32 end,
> gfp_t flags)
> {
> int ret_val = 0;
> - struct netlbl_lsm_secattr_catmap *iter = catmap;
> + struct netlbl_lsm_secattr_catmap *iter = *catmap;
> u32 iter_max_spot;
> u32 spot;
> + u32 orig_spot = iter->startbit;
>
> /* XXX - This could probably be made a bit faster by combining writes
> * to the catmap instead of setting a single bit each time, but for
> @@ -596,7 +604,9 @@ int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap *catmap,
> iter = iter->next;
> iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;
> }
> - ret_val = netlbl_secattr_catmap_setbit(iter, spot, flags);
> + ret_val = netlbl_secattr_catmap_setbit(&iter, spot, flags);
> + if (iter->startbit < orig_spot)
> + *catmap = iter;
> }
>
> return ret_val;
> diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
> index 14293cd..9ecf4f4 100644
> --- a/security/smack/smack_access.c
> +++ b/security/smack/smack_access.c
> @@ -444,7 +444,7 @@ int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
> for (m = 0x80; m != 0; m >>= 1, cat++) {
> if ((m & *cp) == 0)
> continue;
> - rc = netlbl_secattr_catmap_setbit(sap->attr.mls.cat,
> + rc = netlbl_secattr_catmap_setbit(&sap->attr.mls.cat,
> cat, GFP_ATOMIC);
> if (rc < 0) {
> netlbl_secattr_catmap_free(sap->attr.mls.cat);
>
> --
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