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Message-ID: <53DAC7F7.2020603@schaufler-ca.com>
Date: Thu, 31 Jul 2014 15:49:27 -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 2/4] netlabel: fix the horribly broken catmap functions
On 7/31/2014 2:44 PM, Paul Moore wrote:
> The NetLabel secattr catmap functions, and the SELinux import/export
> glue routines, were broken in many horrible ways and the SELinux glue
> code fiddled with the NetLabel catmap structures in ways that we
> probably shouldn't allow. At some point this "worked", but that was
> likely due to a bit of dumb luck and sub-par testing (both inflicted
> by yours truly). This patch corrects these problems by basically
> gutting the code in favor of something less obtuse and restoring the
> NetLabel abstractions in the SELinux catmap glue code.
>
> Everything is working now, and if it decides to break itself in the
> future this code will be much easier to debug than the code it
> replaces.
>
> One noteworthy side effect of the changes is that it is no longer
> necessary to allocate a NetLabel catmap before calling one of the
> NetLabel APIs to set a bit in the catmap. NetLabel will automatically
> allocate the catmap nodes when needed, resulting in less allocations
> when the lowest bit is greater than 255 and less code in the LSMs.
>
> 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 | 26 +++++
> net/ipv4/cipso_ipv4.c | 12 --
> net/netlabel/netlabel_kapi.c | 216 ++++++++++++++++++++++++++++++++---------
> security/selinux/ss/ebitmap.c | 127 +++++++++---------------
> security/smack/smack_access.c | 5 -
> 5 files changed, 240 insertions(+), 146 deletions(-)
>
> diff --git a/include/net/netlabel.h b/include/net/netlabel.h
> index 1c40d65..bda7a12 100644
> --- a/include/net/netlabel.h
> +++ b/include/net/netlabel.h
> @@ -285,11 +285,11 @@ static inline void netlbl_secattr_catmap_free(
> {
> struct netlbl_lsm_secattr_catmap *iter;
>
> - do {
> + while (catmap) {
> iter = catmap;
> catmap = catmap->next;
> kfree(iter);
> - } while (catmap);
> + }
> }
>
> /**
> @@ -394,6 +394,9 @@ 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_getlong(struct netlbl_lsm_secattr_catmap *catmap,
> + u32 *offset,
> + unsigned long *bitmap);
> int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap **catmap,
> u32 bit,
> gfp_t flags);
> @@ -401,6 +404,10 @@ int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap **catmap,
> u32 start,
> u32 end,
> gfp_t flags);
> +int netlbl_secattr_catmap_setlong(struct netlbl_lsm_secattr_catmap **catmap,
> + u32 offset,
> + unsigned long bitmap,
> + gfp_t flags);
>
> /*
> * LSM protocol operations (NetLabel LSM/kernel API)
> @@ -504,6 +511,13 @@ static inline int netlbl_secattr_catmap_walk_rng(
> {
> return -ENOENT;
> }
> +static inline int netlbl_secattr_catmap_getlong(
> + struct netlbl_lsm_secattr_catmap *catmap,
> + u32 *offset,
> + unsigned long *bitmap)
> +{
> + return 0;
> +}
> static inline int netlbl_secattr_catmap_setbit(
> struct netlbl_lsm_secattr_catmap **catmap,
> u32 bit,
> @@ -519,6 +533,14 @@ static inline int netlbl_secattr_catmap_setrng(
> {
> return 0;
> }
> +static int netlbl_secattr_catmap_setlong(
> + struct netlbl_lsm_secattr_catmap **catmap,
> + u32 offset,
> + unsigned long bitmap,
> + gfp_t flags)
> +{
> + return 0;
> +}
> static inline int netlbl_enabled(void)
> {
> return 0;
> diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
> index dd433c9..8a0c7bd 100644
> --- a/net/ipv4/cipso_ipv4.c
> +++ b/net/ipv4/cipso_ipv4.c
> @@ -1335,10 +1335,6 @@ static int cipso_v4_parsetag_rbm(const struct cipso_v4_doi *doi_def,
> secattr->flags |= NETLBL_SECATTR_MLS_LVL;
>
> if (tag_len > 4) {
> - secattr->attr.mls.cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
> - if (secattr->attr.mls.cat == NULL)
> - return -ENOMEM;
> -
> ret_val = cipso_v4_map_cat_rbm_ntoh(doi_def,
> &tag[4],
> tag_len - 4,
> @@ -1430,10 +1426,6 @@ static int cipso_v4_parsetag_enum(const struct cipso_v4_doi *doi_def,
> secattr->flags |= NETLBL_SECATTR_MLS_LVL;
>
> if (tag_len > 4) {
> - secattr->attr.mls.cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
> - if (secattr->attr.mls.cat == NULL)
> - return -ENOMEM;
> -
> ret_val = cipso_v4_map_cat_enum_ntoh(doi_def,
> &tag[4],
> tag_len - 4,
> @@ -1524,10 +1516,6 @@ static int cipso_v4_parsetag_rng(const struct cipso_v4_doi *doi_def,
> secattr->flags |= NETLBL_SECATTR_MLS_LVL;
>
> if (tag_len > 4) {
> - secattr->attr.mls.cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
> - if (secattr->attr.mls.cat == NULL)
> - return -ENOMEM;
> -
> ret_val = cipso_v4_map_cat_rng_ntoh(doi_def,
> &tag[4],
> tag_len - 4,
> diff --git a/net/netlabel/netlabel_kapi.c b/net/netlabel/netlabel_kapi.c
> index 84e810b..d9e1046 100644
> --- a/net/netlabel/netlabel_kapi.c
> +++ b/net/netlabel/netlabel_kapi.c
> @@ -405,6 +405,63 @@ out_entry:
> * Security Attribute Functions
> */
>
> +#define _CM_F_NONE 0x00000000
> +#define _CM_F_ALLOC 0x00000001
> +
> +/**
> + * _netlbl_secattr_catmap_getnode - Get a individual node from a catmap
> + * @catmap: pointer to the category bitmap
> + * @offset: the requested offset
> + * @cm_flags: catmap flags, see _CM_F_*
> + * @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.
> + *
> + */
> +static struct netlbl_lsm_secattr_catmap *_netlbl_secattr_catmap_getnode(
> + struct netlbl_lsm_secattr_catmap **catmap,
> + u32 offset,
> + unsigned int cm_flags,
> + gfp_t gfp_flags)
> +{
> + struct netlbl_lsm_secattr_catmap *iter = *catmap;
> + struct netlbl_lsm_secattr_catmap *prev = NULL;
> +
> + if (iter == NULL || offset < iter->startbit)
> + goto secattr_catmap_getnode_alloc;
> + while (iter && offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
> + prev = iter;
> + iter = iter->next;
> + }
> + if (iter == NULL || offset < iter->startbit)
> + goto secattr_catmap_getnode_alloc;
> +
> + return iter;
> +
> +secattr_catmap_getnode_alloc:
> + if (!(cm_flags & _CM_F_ALLOC))
> + return NULL;
> +
> + iter = netlbl_secattr_catmap_alloc(gfp_flags);
> + if (iter == NULL)
> + return NULL;
> + iter->startbit = offset & ~(NETLBL_CATMAP_SIZE - 1);
> +
> + if (prev == NULL) {
> + iter->next = *catmap;
> + *catmap = iter;
> + } else {
> + iter->next = prev->next;
> + prev->next = iter;
> + }
> +
> + return iter;
> +}
> +
> /**
> * netlbl_secattr_catmap_walk - Walk a LSM secattr catmap looking for a bit
> * @catmap: the category bitmap
> @@ -521,6 +578,54 @@ int netlbl_secattr_catmap_walk_rng(struct netlbl_lsm_secattr_catmap *catmap,
> }
>
> /**
> + * netlbl_secattr_catmap_getlong - Export an unsigned long bitmap
> + * @catmap: pointer to the category bitmap
> + * @offset: pointer to the requested offset
> + * @bitmap: the exported bitmap
> + *
> + * Description:
> + * Export a bitmap with an offset greater than or equal to @offset and return
> + * it in @bitmap. The @offset must be aligned to an unsigned long and will be
> + * updated on return if different from what was requested; if the catmap is
> + * empty at the requested offset and beyond, the @offset is set to (u32)-1.
> + * Returns zero on sucess, negative values on failure.
> + *
> + */
> +int netlbl_secattr_catmap_getlong(struct netlbl_lsm_secattr_catmap *catmap,
> + u32 *offset,
> + unsigned long *bitmap)
> +{
> + struct netlbl_lsm_secattr_catmap *iter;
> + u32 off = *offset;
> + u32 idx;
> +
> + /* only allow aligned offsets */
> + if ((off & (BITS_PER_LONG - 1)) != 0)
> + return -EINVAL;
> +
> + if (off < catmap->startbit) {
> + off = catmap->startbit;
> + *offset = off;
> + }
> + iter = _netlbl_secattr_catmap_getnode(&catmap, off, _CM_F_NONE, 0);
> + if (iter == NULL) {
> + *offset = (u32)-1;
> + return 0;
> + }
> +
> + if (off < iter->startbit) {
> + off = iter->startbit;
> + *offset = off;
> + } else
> + off -= iter->startbit;
> +
> + idx = off / NETLBL_CATMAP_MAPSIZE;
> + *bitmap = iter->bitmap[idx] >> (off % NETLBL_CATMAP_SIZE);
> +
> + return 0;
> +}
> +
> +/**
> * netlbl_secattr_catmap_setbit - Set a bit in a LSM secattr catmap
> * @catmap: pointer to the category bitmap
> * @bit: the bit to set
> @@ -535,32 +640,16 @@ int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap **catmap,
> u32 bit,
> gfp_t flags)
> {
> - struct netlbl_lsm_secattr_catmap *iter = *catmap;
> - u32 node_bit;
> - u32 node_idx;
> + struct netlbl_lsm_secattr_catmap *iter;
> + u32 idx;
>
> - while (iter->next != NULL &&
> - bit >= (iter->startbit + NETLBL_CATMAP_SIZE))
> - iter = iter->next;
> - 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;
> - iter = iter->next;
> - iter->startbit = bit & ~(NETLBL_CATMAP_SIZE - 1);
> - }
> + iter = _netlbl_secattr_catmap_getnode(catmap, bit, _CM_F_ALLOC, flags);
> + if (iter == NULL)
> + return -ENOMEM;
>
> - /* gcc always rounds to zero when doing integer division */
> - node_idx = (bit - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
> - node_bit = bit - iter->startbit - (NETLBL_CATMAP_MAPSIZE * node_idx);
> - iter->bitmap[node_idx] |= NETLBL_CATMAP_BIT << node_bit;
> + bit -= iter->startbit;
> + idx = bit / NETLBL_CATMAP_MAPSIZE;
> + iter->bitmap[idx] |= NETLBL_CATMAP_BIT << (bit % NETLBL_CATMAP_MAPSIZE);
>
> return 0;
> }
> @@ -582,34 +671,61 @@ int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap **catmap,
> u32 end,
> gfp_t flags)
> {
> - int ret_val = 0;
> - 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
> - * right now skipping to the start of the range in the catmap should
> - * be a nice improvement over calling the individual setbit function
> - * repeatedly from a loop. */
> -
> - while (iter->next != NULL &&
> - start >= (iter->startbit + NETLBL_CATMAP_SIZE))
> - iter = iter->next;
> - iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;
> -
> - for (spot = start; spot <= end && ret_val == 0; spot++) {
> - if (spot >= iter_max_spot && iter->next != NULL) {
> - iter = iter->next;
> - iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;
> - }
> - ret_val = netlbl_secattr_catmap_setbit(&iter, spot, flags);
> - if (iter->startbit < orig_spot)
> - *catmap = iter;
> + int rc = 0;
> + u32 spot = start;
> +
> + while (rc == 0 && spot <= end) {
> + if (((spot & (BITS_PER_LONG - 1)) != 0) &&
> + ((end - spot) > BITS_PER_LONG)) {
> + rc = netlbl_secattr_catmap_setlong(catmap,
> + spot,
> + (unsigned long)-1,
> + flags);
> + spot += BITS_PER_LONG;
> + } else
> + rc = netlbl_secattr_catmap_setbit(catmap,
> + spot++,
> + flags);
> }
>
> - return ret_val;
> + return rc;
> +}
> +
> +/**
> + * netlbl_secattr_catmap_setlong - Import an unsigned long bitmap
> + * @catmap: pointer to the category bitmap
> + * @offset: offset to the start of the imported bitmap
> + * @bitmap: the bitmap to import
> + * @flags: memory allocation flags
> + *
> + * Description:
> + * Import the bitmap specified in @bitmap into @catmap, using the offset
> + * in @offset. The offset must be aligned to an unsigned long. Returns zero
> + * on success, negative values on failure.
> + *
> + */
> +int netlbl_secattr_catmap_setlong(struct netlbl_lsm_secattr_catmap **catmap,
> + u32 offset,
> + unsigned long bitmap,
> + gfp_t flags)
> +{
> + struct netlbl_lsm_secattr_catmap *iter;
> + u32 idx;
> +
> + /* only allow aligned offsets */
> + if ((offset & (BITS_PER_LONG - 1)) != 0)
> + return -EINVAL;
> +
> + iter = _netlbl_secattr_catmap_getnode(catmap,
> + offset, _CM_F_ALLOC, flags);
> + if (iter == NULL)
> + return -ENOMEM;
> +
> + offset -= iter->startbit;
> + idx = offset / NETLBL_CATMAP_MAPSIZE;
> + iter->bitmap[idx] |= bitmap << (offset % NETLBL_CATMAP_MAPSIZE);
> +
> + return 0;
> }
>
> /*
> diff --git a/security/selinux/ss/ebitmap.c b/security/selinux/ss/ebitmap.c
> index 820313a..842deca 100644
> --- a/security/selinux/ss/ebitmap.c
> +++ b/security/selinux/ss/ebitmap.c
> @@ -89,48 +89,33 @@ int ebitmap_netlbl_export(struct ebitmap *ebmap,
> struct netlbl_lsm_secattr_catmap **catmap)
> {
> struct ebitmap_node *e_iter = ebmap->node;
> - struct netlbl_lsm_secattr_catmap *c_iter;
> - u32 cmap_idx, cmap_sft;
> - int i;
> -
> - /* NetLabel's NETLBL_CATMAP_MAPTYPE is defined as an array of u64,
> - * however, it is not always compatible with an array of unsigned long
> - * in ebitmap_node.
> - * In addition, you should pay attention the following implementation
> - * assumes unsigned long has a width equal with or less than 64-bit.
> - */
> + unsigned long e_map;
> + u32 offset;
> + unsigned int iter;
> + int rc;
>
> if (e_iter == NULL) {
> *catmap = NULL;
> return 0;
> }
>
> - c_iter = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
> - if (c_iter == NULL)
> - return -ENOMEM;
> - *catmap = c_iter;
> - c_iter->startbit = e_iter->startbit & ~(NETLBL_CATMAP_SIZE - 1);
> + if (*catmap != NULL)
> + netlbl_secattr_catmap_free(*catmap);
> + *catmap = NULL;
>
> while (e_iter) {
> - for (i = 0; i < EBITMAP_UNIT_NUMS; i++) {
> - unsigned int delta, e_startbit, c_endbit;
> -
> - e_startbit = e_iter->startbit + i * EBITMAP_UNIT_SIZE;
> - c_endbit = c_iter->startbit + NETLBL_CATMAP_SIZE;
> - if (e_startbit >= c_endbit) {
> - c_iter->next
> - = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
> - if (c_iter->next == NULL)
> + offset = e_iter->startbit;
> + for (iter = 0; iter < EBITMAP_UNIT_NUMS; iter++) {
> + e_map = e_iter->maps[iter];
> + if (e_map != 0) {
> + rc = netlbl_secattr_catmap_setlong(catmap,
> + offset,
> + e_map,
> + GFP_ATOMIC);
> + if (rc != 0)
> goto netlbl_export_failure;
> - c_iter = c_iter->next;
> - c_iter->startbit
> - = e_startbit & ~(NETLBL_CATMAP_SIZE - 1);
> }
> - delta = e_startbit - c_iter->startbit;
> - cmap_idx = delta / NETLBL_CATMAP_MAPSIZE;
> - cmap_sft = delta % NETLBL_CATMAP_MAPSIZE;
> - c_iter->bitmap[cmap_idx]
> - |= e_iter->maps[i] << cmap_sft;
> + offset += EBITMAP_UNIT_SIZE;
> }
> e_iter = e_iter->next;
> }
> @@ -155,56 +140,42 @@ netlbl_export_failure:
> int ebitmap_netlbl_import(struct ebitmap *ebmap,
> struct netlbl_lsm_secattr_catmap *catmap)
> {
> + int rc;
> struct ebitmap_node *e_iter = NULL;
> - struct ebitmap_node *emap_prev = NULL;
> - struct netlbl_lsm_secattr_catmap *c_iter = catmap;
> - u32 c_idx, c_pos, e_idx, e_sft;
> -
> - /* NetLabel's NETLBL_CATMAP_MAPTYPE is defined as an array of u64,
> - * however, it is not always compatible with an array of unsigned long
> - * in ebitmap_node.
> - * In addition, you should pay attention the following implementation
> - * assumes unsigned long has a width equal with or less than 64-bit.
> - */
> -
> - do {
> - for (c_idx = 0; c_idx < NETLBL_CATMAP_MAPCNT; c_idx++) {
> - unsigned int delta;
> - u64 map = c_iter->bitmap[c_idx];
> -
> - if (!map)
> - continue;
> + struct ebitmap_node *e_prev = NULL;
> + u32 offset = 0, idx;
> + unsigned long bitmap;
> +
> + for (;;) {
> + rc = netlbl_secattr_catmap_getlong(catmap, &offset, &bitmap);
> + if (rc < 0)
> + goto netlbl_import_failure;
> + if (offset == (u32)-1)
> + return 0;
>
> - c_pos = c_iter->startbit
> - + c_idx * NETLBL_CATMAP_MAPSIZE;
> - if (!e_iter
> - || c_pos >= e_iter->startbit + EBITMAP_SIZE) {
> - e_iter = kzalloc(sizeof(*e_iter), GFP_ATOMIC);
> - if (!e_iter)
> - goto netlbl_import_failure;
> - e_iter->startbit
> - = c_pos - (c_pos % EBITMAP_SIZE);
> - if (emap_prev == NULL)
> - ebmap->node = e_iter;
> - else
> - emap_prev->next = e_iter;
> - emap_prev = e_iter;
> - }
> - delta = c_pos - e_iter->startbit;
> - e_idx = delta / EBITMAP_UNIT_SIZE;
> - e_sft = delta % EBITMAP_UNIT_SIZE;
> - while (map) {
> - e_iter->maps[e_idx++] |= map & (-1UL);
> - map = EBITMAP_SHIFT_UNIT_SIZE(map);
> - }
> + if (e_iter == NULL ||
> + offset >= e_iter->startbit + EBITMAP_SIZE) {
> + e_prev = e_iter;
> + e_iter = kzalloc(sizeof(*e_iter), GFP_ATOMIC);
> + if (e_iter == NULL)
> + goto netlbl_import_failure;
> + e_iter->startbit = offset & ~(EBITMAP_SIZE - 1);
> + if (e_prev == NULL)
> + ebmap->node = e_iter;
> + else
> + e_prev->next = e_iter;
> + ebmap->highbit = e_iter->startbit + EBITMAP_SIZE;
> }
> - c_iter = c_iter->next;
> - } while (c_iter);
> - if (e_iter != NULL)
> - ebmap->highbit = e_iter->startbit + EBITMAP_SIZE;
> - else
> - ebitmap_destroy(ebmap);
>
> + /* offset will always be aligned to an unsigned long */
> + idx = EBITMAP_NODE_INDEX(e_iter, offset);
> + e_iter->maps[idx] = bitmap;
> +
> + /* next */
> + offset += EBITMAP_UNIT_SIZE;
> + }
> +
> + /* NOTE: we should never reach this return */
> return 0;
>
> netlbl_import_failure:
> diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
> index 9ecf4f4..ea1bc50 100644
> --- a/security/smack/smack_access.c
> +++ b/security/smack/smack_access.c
> @@ -435,10 +435,7 @@ int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
>
> sap->flags |= NETLBL_SECATTR_MLS_CAT;
> sap->attr.mls.lvl = level;
> - sap->attr.mls.cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
> - if (!sap->attr.mls.cat)
> - return -ENOMEM;
> - sap->attr.mls.cat->startbit = 0;
> + sap->attr.mls.cat = NULL;
>
> for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
> for (m = 0x80; m != 0; m >>= 1, cat++) {
>
> --
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