Date: Mon, 1 Nov 2021 14:33:02 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 75306778f149 - stable/13 - vfs: Add KASAN state transitions for vnodes Message-ID: <202111011433.1A1EX2hV021418@gitrepo.freebsd.org>
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The branch stable/13 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=75306778f149e281f03ab9de7b3e1dc185e05c3e commit 75306778f149e281f03ab9de7b3e1dc185e05c3e Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2021-04-13 21:40:11 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2021-11-01 14:03:19 +0000 vfs: Add KASAN state transitions for vnodes vnodes are a bit special in that they may exist on per-CPU lists even while free. Add a KASAN-only destructor that poisons regions of each vnode that are not expected to be accessed after a free. Sponsored by: The FreeBSD Foundation (cherry picked from commit b261bb4057f4abbc1366e4af8e9e4081d039be4a) --- sys/kern/vfs_subr.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 64 insertions(+), 2 deletions(-) diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c index 76e01d1f7816..da2f90a44d86 100644 --- a/sys/kern/vfs_subr.c +++ b/sys/kern/vfs_subr.c @@ -48,6 +48,7 @@ __FBSDID("$FreeBSD$"); #include <sys/param.h> #include <sys/systm.h> +#include <sys/asan.h> #include <sys/bio.h> #include <sys/buf.h> #include <sys/capsicum.h> @@ -511,6 +512,54 @@ vn_free_marker(struct vnode *vp) free(vp, M_VNODE_MARKER); } +#ifdef KASAN +static int +vnode_ctor(void *mem, int size, void *arg __unused, int flags __unused) +{ + kasan_mark(mem, size, roundup2(size, UMA_ALIGN_PTR + 1), 0); + return (0); +} + +static void +vnode_dtor(void *mem, int size, void *arg __unused) +{ + size_t end1, end2, off1, off2; + + _Static_assert(offsetof(struct vnode, v_vnodelist) < + offsetof(struct vnode, v_dbatchcpu), + "KASAN marks require updating"); + + off1 = offsetof(struct vnode, v_vnodelist); + off2 = offsetof(struct vnode, v_dbatchcpu); + end1 = off1 + sizeof(((struct vnode *)NULL)->v_vnodelist); + end2 = off2 + sizeof(((struct vnode *)NULL)->v_dbatchcpu); + + /* + * Access to the v_vnodelist and v_dbatchcpu fields are permitted even + * after the vnode has been freed. Try to get some KASAN coverage by + * marking everything except those two fields as invalid. Because + * KASAN's tracking is not byte-granular, any preceding fields sharing + * the same 8-byte aligned word must also be marked valid. + */ + + /* Handle the area from the start until v_vnodelist... */ + off1 = rounddown2(off1, KASAN_SHADOW_SCALE); + kasan_mark(mem, off1, off1, KASAN_UMA_FREED); + + /* ... then the area between v_vnodelist and v_dbatchcpu ... */ + off1 = roundup2(end1, KASAN_SHADOW_SCALE); + off2 = rounddown2(off2, KASAN_SHADOW_SCALE); + if (off2 > off1) + kasan_mark((void *)((char *)mem + off1), off2 - off1, + off2 - off1, KASAN_UMA_FREED); + + /* ... and finally the area from v_dbatchcpu to the end. */ + off2 = roundup2(end2, KASAN_SHADOW_SCALE); + kasan_mark((void *)((char *)mem + off2), size - off2, size - off2, + KASAN_UMA_FREED); +} +#endif /* KASAN */ + /* * Initialize a vnode as it first enters the zone. */ @@ -576,6 +625,8 @@ vnode_fini(void *mem, int size) mtx_destroy(&vp->v_interlock); bo = &vp->v_bufobj; rw_destroy(BO_LOCKPTR(bo)); + + kasan_mark(mem, size, size, 0); } /* @@ -603,6 +654,8 @@ static void vntblinit(void *dummy __unused) { struct vdbatch *vd; + uma_ctor ctor; + uma_dtor dtor; int cpu, physvnodes, virtvnodes; u_int i; @@ -642,9 +695,18 @@ vntblinit(void *dummy __unused) TAILQ_INSERT_HEAD(&vnode_list, vnode_list_free_marker, v_vnodelist); vnode_list_reclaim_marker = vn_alloc_marker(NULL); TAILQ_INSERT_HEAD(&vnode_list, vnode_list_reclaim_marker, v_vnodelist); - vnode_zone = uma_zcreate("VNODE", sizeof (struct vnode), NULL, NULL, - vnode_init, vnode_fini, UMA_ALIGN_PTR, 0); + +#ifdef KASAN + ctor = vnode_ctor; + dtor = vnode_dtor; +#else + ctor = NULL; + dtor = NULL; +#endif + vnode_zone = uma_zcreate("VNODE", sizeof(struct vnode), ctor, dtor, + vnode_init, vnode_fini, UMA_ALIGN_PTR, UMA_ZONE_NOKASAN); uma_zone_set_smr(vnode_zone, vfs_smr); + /* * Preallocate enough nodes to support one-per buf so that * we can not fail an insert. reassignbuf() callers can not
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