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vfs: stricter validation for flags passed to namei in cn_flags

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namei de facto expects that the naimeidata object is properly initialized,
but at the same time it mixes consumer-passable and internal flags, while
tolerating this part by explicitly clearing some of them.

Tighten the interface instead.

While here renumber the flags and denote the gap between the 2 variants.

Try to piggy back th renumber on the just bumped __FreeBSD_version.
This commit is contained in:
Mateusz Guzik 2020-08-11 01:34:40 +00:00
parent 8d2105da16
commit 2d0631dd08
2 changed files with 30 additions and 18 deletions
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9
sys/kern/vfs_lookup.c
View File

@ -61,6 +61,9 @@ __FBSDID("$FreeBSD$");
#ifdef KTRACE
#include <sys/ktrace.h>
#endif
#ifdef INVARIANTS
#include <machine/_inttypes.h>
#endif
#include <security/audit/audit.h>
#include <security/mac/mac_framework.h>
@ -484,15 +487,15 @@ namei(struct nameidata *ndp)
("namei: nameiop contaminated with flags"));
KASSERT((cnp->cn_flags & OPMASK) == 0,
("namei: flags contaminated with nameiops"));
KASSERT((cnp->cn_flags & NAMEI_INTERNAL_FLAGS) == 0,
("namei: unexpected flags: %" PRIx64 "\n",
cnp->cn_flags & NAMEI_INTERNAL_FLAGS));
if (cnp->cn_flags & NOCACHE)
KASSERT(cnp->cn_nameiop != LOOKUP,
("%s: NOCACHE passed with LOOKUP", __func__));
MPASS(ndp->ni_startdir == NULL || ndp->ni_startdir->v_type == VDIR ||
ndp->ni_startdir->v_type == VBAD);
/* We will set this ourselves if we need it. */
cnp->cn_flags &= ~TRAILINGSLASH;
ndp->ni_lcf = 0;
ndp->ni_vp = NULL;

39
sys/sys/namei.h
View File

@ -152,23 +152,32 @@ int cache_fplookup(struct nameidata *ndp, enum cache_fpl_status *status,
#define HASBUF 0x00000400 /* has allocated pathname buffer */
#define SAVENAME 0x00000800 /* save pathname buffer */
#define SAVESTART 0x00001000 /* save starting directory */
#define ISDOTDOT 0x00002000 /* current component name is .. */
#define MAKEENTRY 0x00004000 /* entry is to be added to name cache */
#define ISLASTCN 0x00008000 /* this is last component of pathname */
#define ISSYMLINK 0x00010000 /* symlink needs interpretation */
#define ISWHITEOUT 0x00020000 /* found whiteout */
#define DOWHITEOUT 0x00040000 /* do whiteouts */
#define WILLBEDIR 0x00080000 /* new files will be dirs; allow trailing / */
#define ISOPEN 0x00200000 /* caller is opening; return a real vnode. */
#define NOCROSSMOUNT 0x00400000 /* do not cross mount points */
#define NOMACCHECK 0x00800000 /* do not perform MAC checks */
#define AUDITVNODE1 0x04000000 /* audit the looked up vnode information */
#define AUDITVNODE2 0x08000000 /* audit the looked up vnode information */
#define TRAILINGSLASH 0x10000000 /* path ended in a slash */
#define NOCAPCHECK 0x20000000 /* do not perform capability checks */
#define NOEXECCHECK 0x40000000 /* do not perform exec check on dir */
#define ISWHITEOUT 0x00002000 /* found whiteout */
#define DOWHITEOUT 0x00004000 /* do whiteouts */
#define WILLBEDIR 0x00008000 /* new files will be dirs; allow trailing / */
#define ISOPEN 0x00010000 /* caller is opening; return a real vnode. */
#define NOCROSSMOUNT 0x00020000 /* do not cross mount points */
#define NOMACCHECK 0x00040000 /* do not perform MAC checks */
#define AUDITVNODE1 0x00080000 /* audit the looked up vnode information */
#define AUDITVNODE2 0x00100000 /* audit the looked up vnode information */
#define NOCAPCHECK 0x00200000 /* do not perform capability checks */
/* UNUSED 0x00400000 */
/* UNUSED 0x00800000 */
/* UNUSED 0x01000000 */
#define NOEXECCHECK 0x02000000 /* do not perform exec check on dir */
#define MAKEENTRY 0x04000000 /* entry is to be added to name cache */
#define ISSYMLINK 0x08000000 /* symlink needs interpretation */
#define ISLASTCN 0x10000000 /* this is last component of pathname */
#define ISDOTDOT 0x20000000 /* current component name is .. */
#define TRAILINGSLASH 0x40000000 /* path ended in a slash */
#define PARAMASK 0x7ffffe00 /* mask of parameter descriptors */
/*
* Flags which must not be passed in by callers.
*/
#define NAMEI_INTERNAL_FLAGS \
(NOEXECCHECK | MAKEENTRY | ISSYMLINK | ISLASTCN | ISDOTDOT | TRAILINGSLASH)
/*
* Namei results flags
*/