81243eacfa
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. Link: http://lkml.kernel.org/r/20160817201927.GA2096@p183.telecom.by Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Vasily Kulikov <segoon@openwall.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
91 lines
2 KiB
C
91 lines
2 KiB
C
/* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de> */
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#include <linux/sched.h>
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#include "nfsd.h"
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#include "auth.h"
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int nfsexp_flags(struct svc_rqst *rqstp, struct svc_export *exp)
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{
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struct exp_flavor_info *f;
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struct exp_flavor_info *end = exp->ex_flavors + exp->ex_nflavors;
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for (f = exp->ex_flavors; f < end; f++) {
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if (f->pseudoflavor == rqstp->rq_cred.cr_flavor)
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return f->flags;
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}
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return exp->ex_flags;
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}
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int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
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{
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struct group_info *rqgi;
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struct group_info *gi;
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struct cred *new;
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int i;
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int flags = nfsexp_flags(rqstp, exp);
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validate_process_creds();
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/* discard any old override before preparing the new set */
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revert_creds(get_cred(current_real_cred()));
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new = prepare_creds();
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if (!new)
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return -ENOMEM;
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new->fsuid = rqstp->rq_cred.cr_uid;
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new->fsgid = rqstp->rq_cred.cr_gid;
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rqgi = rqstp->rq_cred.cr_group_info;
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if (flags & NFSEXP_ALLSQUASH) {
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new->fsuid = exp->ex_anon_uid;
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new->fsgid = exp->ex_anon_gid;
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gi = groups_alloc(0);
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if (!gi)
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goto oom;
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} else if (flags & NFSEXP_ROOTSQUASH) {
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if (uid_eq(new->fsuid, GLOBAL_ROOT_UID))
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new->fsuid = exp->ex_anon_uid;
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if (gid_eq(new->fsgid, GLOBAL_ROOT_GID))
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new->fsgid = exp->ex_anon_gid;
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gi = groups_alloc(rqgi->ngroups);
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if (!gi)
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goto oom;
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for (i = 0; i < rqgi->ngroups; i++) {
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if (gid_eq(GLOBAL_ROOT_GID, rqgi->gid[i]))
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gi->gid[i] = exp->ex_anon_gid;
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else
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gi->gid[i] = rqgi->gid[i];
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}
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} else {
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gi = get_group_info(rqgi);
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}
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if (uid_eq(new->fsuid, INVALID_UID))
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new->fsuid = exp->ex_anon_uid;
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if (gid_eq(new->fsgid, INVALID_GID))
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new->fsgid = exp->ex_anon_gid;
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set_groups(new, gi);
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put_group_info(gi);
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if (!uid_eq(new->fsuid, GLOBAL_ROOT_UID))
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new->cap_effective = cap_drop_nfsd_set(new->cap_effective);
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else
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new->cap_effective = cap_raise_nfsd_set(new->cap_effective,
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new->cap_permitted);
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validate_process_creds();
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put_cred(override_creds(new));
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put_cred(new);
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validate_process_creds();
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return 0;
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oom:
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abort_creds(new);
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return -ENOMEM;
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}
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