From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753636AbcHQUTu (ORCPT ); Wed, 17 Aug 2016 16:19:50 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:35151 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753007AbcHQUT0 (ORCPT ); Wed, 17 Aug 2016 16:19:26 -0400 Date: Wed, 17 Aug 2016 23:19:27 +0300 From: Alexey Dobriyan To: akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, segoon@openwall.com, linux-nfs@vger.kernel.org Subject: [PATCH] cred: simpler, 1D supplementary groups Message-ID: <20160817201927.GA2096@p183.telecom.by> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Current supplementary groups code can massively overallocate memory and is implemented in a way so that access to individual gid is done via 2D array. If number of gids is <= 32, memory allocation is more or less tolerable (140/148 bytes). But if it is not, code allocates full page (!) regardless and, what's even more fun, doesn't reuse small 32-entry array. 2D array means dependent shifts, loads and LEAs without possibility to optimize them (gid is never known at compile time). All of the above is unnecessary. Switch to the usual trailing-zero-len-array scheme. Memory is allocated with kmalloc/vmalloc() and only as much as needed. Accesses become simpler (LEA 8(gi,idx,4) or even without displacement). Maximum number of gids is 65536 which translates to 256KB+8 bytes. I think kernel can handle such allocation. On my usual desktop system with whole 9 (nine) aux groups, struct group_info shrinks from 148 bytes to 44 bytes, yay! Nice side effects: * "gi->gid[i]" is shorter than "GROUP_AT(gi, i)", less typing, * fix little mess in net/ipv4/ping.c should have been using GROUP_AT macro but this point becomes moot, * aux group allocation is persistent and should be accounted as such. Signed-off-by: Alexey Dobriyan --- arch/s390/kernel/compat_linux.c | 4 - drivers/staging/lustre/lustre/ptlrpc/sec.c | 2 fs/nfsd/auth.c | 6 +- fs/nfsd/nfs4state.c | 2 fs/proc/array.c | 2 include/linux/cred.h | 11 ---- kernel/groups.c | 67 +++++++++-------------------- kernel/uid16.c | 4 - net/ipv4/ping.c | 15 ++---- net/sunrpc/auth_generic.c | 4 - net/sunrpc/auth_gss/gss_rpc_xdr.c | 2 net/sunrpc/auth_gss/svcauth_gss.c | 2 net/sunrpc/auth_unix.c | 4 - net/sunrpc/svcauth_unix.c | 6 +- 14 files changed, 46 insertions(+), 85 deletions(-) --- a/arch/s390/kernel/compat_linux.c +++ b/arch/s390/kernel/compat_linux.c @@ -189,7 +189,7 @@ static int groups16_to_user(u16 __user *grouplist, struct group_info *group_info kgid_t kgid; for (i = 0; i < group_info->ngroups; i++) { - kgid = GROUP_AT(group_info, i); + kgid = group_info->gid[i]; group = (u16)from_kgid_munged(user_ns, kgid); if (put_user(group, grouplist+i)) return -EFAULT; @@ -213,7 +213,7 @@ static int groups16_from_user(struct group_info *group_info, u16 __user *groupli if (!gid_valid(kgid)) return -EINVAL; - GROUP_AT(group_info, i) = kgid; + group_info->gid[i] = kgid; } return 0; --- a/drivers/staging/lustre/lustre/ptlrpc/sec.c +++ b/drivers/staging/lustre/lustre/ptlrpc/sec.c @@ -2204,7 +2204,7 @@ int sptlrpc_pack_user_desc(struct lustre_msg *msg, int offset) task_lock(current); if (pud->pud_ngroups > current_ngroups) pud->pud_ngroups = current_ngroups; - memcpy(pud->pud_groups, current_cred()->group_info->blocks[0], + memcpy(pud->pud_groups, current_cred()->group_info->gid, pud->pud_ngroups * sizeof(__u32)); task_unlock(current); --- a/fs/nfsd/auth.c +++ b/fs/nfsd/auth.c @@ -55,10 +55,10 @@ int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp) goto oom; for (i = 0; i < rqgi->ngroups; i++) { - if (gid_eq(GLOBAL_ROOT_GID, GROUP_AT(rqgi, i))) - GROUP_AT(gi, i) = exp->ex_anon_gid; + if (gid_eq(GLOBAL_ROOT_GID, rqgi->gid[i])) + gi->gid[i] = exp->ex_anon_gid; else - GROUP_AT(gi, i) = GROUP_AT(rqgi, i); + gi->gid[i] = rqgi->gid[i]; } } else { gi = get_group_info(rqgi); --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1903,7 +1903,7 @@ static bool groups_equal(struct group_info *g1, struct group_info *g2) if (g1->ngroups != g2->ngroups) return false; for (i=0; ingroups; i++) - if (!gid_eq(GROUP_AT(g1, i), GROUP_AT(g2, i))) + if (!gid_eq(g1->gid[i], g2->gid[i])) return false; return true; } --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -211,7 +211,7 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, group_info = cred->group_info; for (g = 0; g < group_info->ngroups; g++) seq_printf(m, "%d ", - from_kgid_munged(user_ns, GROUP_AT(group_info, g))); + from_kgid_munged(user_ns, group_info->gid[g])); put_cred(cred); #ifdef CONFIG_PID_NS --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -26,15 +26,10 @@ struct inode; /* * COW Supplementary groups list */ -#define NGROUPS_SMALL 32 -#define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(kgid_t))) - struct group_info { atomic_t usage; int ngroups; - int nblocks; - kgid_t small_block[NGROUPS_SMALL]; - kgid_t *blocks[0]; + kgid_t gid[0]; }; /** @@ -88,10 +83,6 @@ extern void set_groups(struct cred *, struct group_info *); extern int groups_search(const struct group_info *, kgid_t); extern bool may_setgroups(void); -/* access the groups "array" with this macro */ -#define GROUP_AT(gi, i) \ - ((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK]) - /* * The security context of a task * --- a/kernel/groups.c +++ b/kernel/groups.c @@ -7,55 +7,31 @@ #include #include #include +#include #include struct group_info *groups_alloc(int gidsetsize) { - struct group_info *group_info; - int nblocks; - int i; - - nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK; - /* Make sure we always allocate at least one indirect block pointer */ - nblocks = nblocks ? : 1; - group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER); - if (!group_info) + struct group_info *gi; + unsigned int len; + + len = sizeof(struct group_info) + sizeof(kgid_t) * gidsetsize; + gi = kmalloc(len, GFP_KERNEL_ACCOUNT|__GFP_NOWARN|__GFP_NORETRY); + if (!gi) + gi = __vmalloc(len, GFP_KERNEL_ACCOUNT|__GFP_HIGHMEM, PAGE_KERNEL); + if (!gi) return NULL; - group_info->ngroups = gidsetsize; - group_info->nblocks = nblocks; - atomic_set(&group_info->usage, 1); - - if (gidsetsize <= NGROUPS_SMALL) - group_info->blocks[0] = group_info->small_block; - else { - for (i = 0; i < nblocks; i++) { - kgid_t *b; - b = (void *)__get_free_page(GFP_USER); - if (!b) - goto out_undo_partial_alloc; - group_info->blocks[i] = b; - } - } - return group_info; -out_undo_partial_alloc: - while (--i >= 0) { - free_page((unsigned long)group_info->blocks[i]); - } - kfree(group_info); - return NULL; + atomic_set(&gi->usage, 1); + gi->ngroups = gidsetsize; + return gi; } EXPORT_SYMBOL(groups_alloc); void groups_free(struct group_info *group_info) { - if (group_info->blocks[0] != group_info->small_block) { - int i; - for (i = 0; i < group_info->nblocks; i++) - free_page((unsigned long)group_info->blocks[i]); - } - kfree(group_info); + kvfree(group_info); } EXPORT_SYMBOL(groups_free); @@ -70,7 +46,7 @@ static int groups_to_user(gid_t __user *grouplist, for (i = 0; i < count; i++) { gid_t gid; - gid = from_kgid_munged(user_ns, GROUP_AT(group_info, i)); + gid = from_kgid_munged(user_ns, group_info->gid[i]); if (put_user(gid, grouplist+i)) return -EFAULT; } @@ -95,7 +71,7 @@ static int groups_from_user(struct group_info *group_info, if (!gid_valid(kgid)) return -EINVAL; - GROUP_AT(group_info, i) = kgid; + group_info->gid[i] = kgid; } return 0; } @@ -115,15 +91,14 @@ static void groups_sort(struct group_info *group_info) for (base = 0; base < max; base++) { int left = base; int right = left + stride; - kgid_t tmp = GROUP_AT(group_info, right); + kgid_t tmp = group_info->gid[right]; - while (left >= 0 && gid_gt(GROUP_AT(group_info, left), tmp)) { - GROUP_AT(group_info, right) = - GROUP_AT(group_info, left); + while (left >= 0 && gid_gt(group_info->gid[left], tmp)) { + group_info->gid[right] = group_info->gid[left]; right = left; left -= stride; } - GROUP_AT(group_info, right) = tmp; + group_info->gid[right] = tmp; } stride /= 3; } @@ -141,9 +116,9 @@ int groups_search(const struct group_info *group_info, kgid_t grp) right = group_info->ngroups; while (left < right) { unsigned int mid = (left+right)/2; - if (gid_gt(grp, GROUP_AT(group_info, mid))) + if (gid_gt(grp, group_info->gid[mid])) left = mid + 1; - else if (gid_lt(grp, GROUP_AT(group_info, mid))) + else if (gid_lt(grp, group_info->gid[mid])) right = mid; else return 1; --- a/kernel/uid16.c +++ b/kernel/uid16.c @@ -117,7 +117,7 @@ static int groups16_to_user(old_gid_t __user *grouplist, kgid_t kgid; for (i = 0; i < group_info->ngroups; i++) { - kgid = GROUP_AT(group_info, i); + kgid = group_info->gid[i]; group = high2lowgid(from_kgid_munged(user_ns, kgid)); if (put_user(group, grouplist+i)) return -EFAULT; @@ -142,7 +142,7 @@ static int groups16_from_user(struct group_info *group_info, if (!gid_valid(kgid)) return -EINVAL; - GROUP_AT(group_info, i) = kgid; + group_info->gid[i] = kgid; } return 0; --- a/net/ipv4/ping.c +++ b/net/ipv4/ping.c @@ -258,7 +258,7 @@ int ping_init_sock(struct sock *sk) struct net *net = sock_net(sk); kgid_t group = current_egid(); struct group_info *group_info; - int i, j, count; + int i; kgid_t low, high; int ret = 0; @@ -270,16 +270,11 @@ int ping_init_sock(struct sock *sk) return 0; group_info = get_current_groups(); - count = group_info->ngroups; - for (i = 0; i < group_info->nblocks; i++) { - int cp_count = min_t(int, NGROUPS_PER_BLOCK, count); - for (j = 0; j < cp_count; j++) { - kgid_t gid = group_info->blocks[i][j]; - if (gid_lte(low, gid) && gid_lte(gid, high)) - goto out_release_group; - } + for (i = 0; i < group_info->ngroups; i++) { + kgid_t gid = group_info->gid[i]; - count -= cp_count; + if (gid_lte(low, gid) && gid_lte(gid, high)) + goto out_release_group; } ret = -EACCES; --- a/net/sunrpc/auth_generic.c +++ b/net/sunrpc/auth_generic.c @@ -176,8 +176,8 @@ generic_match(struct auth_cred *acred, struct rpc_cred *cred, int flags) if (gcred->acred.group_info->ngroups != acred->group_info->ngroups) goto out_nomatch; for (i = 0; i < gcred->acred.group_info->ngroups; i++) { - if (!gid_eq(GROUP_AT(gcred->acred.group_info, i), - GROUP_AT(acred->group_info, i))) + if (!gid_eq(gcred->acred.group_info->gid[i], + acred->group_info->gid[i])) goto out_nomatch; } out_match: --- a/net/sunrpc/auth_gss/gss_rpc_xdr.c +++ b/net/sunrpc/auth_gss/gss_rpc_xdr.c @@ -229,7 +229,7 @@ static int gssx_dec_linux_creds(struct xdr_stream *xdr, kgid = make_kgid(&init_user_ns, tmp); if (!gid_valid(kgid)) goto out_free_groups; - GROUP_AT(creds->cr_group_info, i) = kgid; + creds->cr_group_info->gid[i] = kgid; } return 0; --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -479,7 +479,7 @@ static int rsc_parse(struct cache_detail *cd, kgid = make_kgid(&init_user_ns, id); if (!gid_valid(kgid)) goto out; - GROUP_AT(rsci.cred.cr_group_info, i) = kgid; + rsci.cred.cr_group_info->gid[i] = kgid; } /* mech name */ --- a/net/sunrpc/auth_unix.c +++ b/net/sunrpc/auth_unix.c @@ -79,7 +79,7 @@ unx_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags, gfp_t cred->uc_gid = acred->gid; for (i = 0; i < groups; i++) - cred->uc_gids[i] = GROUP_AT(acred->group_info, i); + cred->uc_gids[i] = acred->group_info->gid[i]; if (i < NFS_NGROUPS) cred->uc_gids[i] = INVALID_GID; @@ -127,7 +127,7 @@ unx_match(struct auth_cred *acred, struct rpc_cred *rcred, int flags) if (groups > NFS_NGROUPS) groups = NFS_NGROUPS; for (i = 0; i < groups ; i++) - if (!gid_eq(cred->uc_gids[i], GROUP_AT(acred->group_info, i))) + if (!gid_eq(cred->uc_gids[i], acred->group_info->gid[i])) return 0; if (groups < NFS_NGROUPS && gid_valid(cred->uc_gids[groups])) return 0; --- a/net/sunrpc/svcauth_unix.c +++ b/net/sunrpc/svcauth_unix.c @@ -517,7 +517,7 @@ static int unix_gid_parse(struct cache_detail *cd, kgid = make_kgid(&init_user_ns, gid); if (!gid_valid(kgid)) goto out; - GROUP_AT(ug.gi, i) = kgid; + ug.gi->gid[i] = kgid; } ugp = unix_gid_lookup(cd, uid); @@ -564,7 +564,7 @@ static int unix_gid_show(struct seq_file *m, seq_printf(m, "%u %d:", from_kuid_munged(user_ns, ug->uid), glen); for (i = 0; i < glen; i++) - seq_printf(m, " %d", from_kgid_munged(user_ns, GROUP_AT(ug->gi, i))); + seq_printf(m, " %d", from_kgid_munged(user_ns, ug->gi->gid[i])); seq_printf(m, "\n"); return 0; } @@ -817,7 +817,7 @@ svcauth_unix_accept(struct svc_rqst *rqstp, __be32 *authp) return SVC_CLOSE; for (i = 0; i < slen; i++) { kgid_t kgid = make_kgid(&init_user_ns, svc_getnl(argv)); - GROUP_AT(cred->cr_group_info, i) = kgid; + cred->cr_group_info->gid[i] = kgid; } if (svc_getu32(argv) != htonl(RPC_AUTH_NULL) || svc_getu32(argv) != 0) { *authp = rpc_autherr_badverf;