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authorKonstantin Belousov <kib@FreeBSD.org>2020-09-22 22:48:12 +0000
committerKonstantin Belousov <kib@FreeBSD.org>2020-09-22 22:48:12 +0000
commit1317da4349f7295eb5153c791cf034730c31d0ea (patch)
tree1ac1c30ff751e3e2fa0e2d1e3c689e2c71c51037
parent6a9c72d901feeca0b0865be8954a3a29d8613b34 (diff)
downloadsrc-1317da4349f7295eb5153c791cf034730c31d0ea.tar.gz
src-1317da4349f7295eb5153c791cf034730c31d0ea.zip
Add O_RESOLVE_BENEATH and AT_RESOLVE_BENEATH to mimic Linux' RESOLVE_BENEATH.
It is like O_BENEATH, but disables to walk out of the subtree rooted in the starting directory. O_BENEATH does not care if path walks out if it returned. Requested by: Dan Gohman <dev@sunfishcode.online> PR: 248335 Reviewed by: markj Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D25886
Notes
Notes: svn path=/head/; revision=366022
-rw-r--r--sys/kern/vfs_lookup.c10
-rw-r--r--sys/kern/vfs_syscalls.c46
-rw-r--r--sys/kern/vfs_vnops.c2
-rw-r--r--sys/sys/fcntl.h6
-rw-r--r--sys/sys/namei.h3
5 files changed, 48 insertions, 19 deletions
diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c
index e13888a4a3c0..d382d0a6c429 100644
--- a/sys/kern/vfs_lookup.c
+++ b/sys/kern/vfs_lookup.c
@@ -428,6 +428,16 @@ namei_setup(struct nameidata *ndp, struct vnode **dpp, struct pwd **pwdp)
if (error == 0)
ndp->ni_lcf |= NI_LCF_LATCH;
}
+ if (error == 0 && (cnp->cn_flags & RBENEATH) != 0) {
+ if (cnp->cn_pnbuf[0] == '/' ||
+ (ndp->ni_lcf & NI_LCF_BENEATH_ABS) != 0) {
+ error = EINVAL;
+ } else if ((ndp->ni_lcf & NI_LCF_STRICTRELATIVE) == 0) {
+ ndp->ni_lcf |= NI_LCF_STRICTRELATIVE |
+ NI_LCF_CAP_DOTDOT;
+ }
+ }
+
/*
* If we are auditing the kernel pathname, save the user pathname.
*/
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index 9eec74d4da22..136631690bc6 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -124,6 +124,8 @@ at2cnpflags(u_int at_flags, u_int mask)
at_flags &= mask;
if ((at_flags & AT_BENEATH) != 0)
res |= BENEATH;
+ if ((at_flags & AT_RESOLVE_BENEATH) != 0)
+ res |= RBENEATH;
if ((at_flags & AT_SYMLINK_FOLLOW) != 0)
res |= FOLLOW;
/* NOFOLLOW is pseudo flag */
@@ -1503,11 +1505,13 @@ sys_linkat(struct thread *td, struct linkat_args *uap)
int flag;
flag = uap->flag;
- if ((flag & ~(AT_SYMLINK_FOLLOW | AT_BENEATH)) != 0)
+ if ((flag & ~(AT_SYMLINK_FOLLOW | AT_BENEATH |
+ AT_RESOLVE_BENEATH)) != 0)
return (EINVAL);
return (kern_linkat(td, uap->fd1, uap->fd2, uap->path1, uap->path2,
- UIO_USERSPACE, at2cnpflags(flag, AT_SYMLINK_FOLLOW | AT_BENEATH)));
+ UIO_USERSPACE, at2cnpflags(flag, AT_SYMLINK_FOLLOW | AT_BENEATH |
+ AT_RESOLVE_BENEATH)));
}
int hardlink_check_uid = 0;
@@ -1872,7 +1876,7 @@ kern_funlinkat(struct thread *td, int dfd, const char *path, int fd,
restart:
bwillwrite();
NDINIT_ATRIGHTS(&nd, DELETE, LOCKPARENT | LOCKLEAF | AUDITVNODE1 |
- at2cnpflags(flag, AT_BENEATH),
+ at2cnpflags(flag, AT_BENEATH | AT_RESOLVE_BENEATH),
pathseg, path, dfd, &cap_unlinkat_rights, td);
if ((error = namei(&nd)) != 0) {
if (error == EINVAL)
@@ -2075,7 +2079,7 @@ kern_accessat(struct thread *td, int fd, const char *path,
struct nameidata nd;
int error;
- if ((flag & ~(AT_EACCESS | AT_BENEATH)) != 0)
+ if ((flag & ~(AT_EACCESS | AT_BENEATH | AT_RESOLVE_BENEATH)) != 0)
return (EINVAL);
if (amode != F_OK && (amode & ~(R_OK | W_OK | X_OK)) != 0)
return (EINVAL);
@@ -2096,7 +2100,7 @@ kern_accessat(struct thread *td, int fd, const char *path,
usecred = cred;
AUDIT_ARG_VALUE(amode);
NDINIT_ATRIGHTS(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF |
- AUDITVNODE1 | at2cnpflags(flag, AT_BENEATH),
+ AUDITVNODE1 | at2cnpflags(flag, AT_BENEATH | AT_RESOLVE_BENEATH),
pathseg, path, fd, &cap_fstat_rights, td);
if ((error = namei(&nd)) != 0)
goto out;
@@ -2387,11 +2391,12 @@ kern_statat(struct thread *td, int flag, int fd, const char *path,
struct nameidata nd;
int error;
- if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_BENEATH)) != 0)
+ if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_BENEATH |
+ AT_RESOLVE_BENEATH)) != 0)
return (EINVAL);
NDINIT_ATRIGHTS(&nd, LOOKUP, at2cnpflags(flag, AT_BENEATH |
- AT_SYMLINK_NOFOLLOW) | LOCKSHARED | LOCKLEAF |
+ AT_RESOLVE_BENEATH | AT_SYMLINK_NOFOLLOW) | LOCKSHARED | LOCKLEAF |
AUDITVNODE1, pathseg, path, fd, &cap_fstat_rights, td);
if ((error = namei(&nd)) != 0)
@@ -2710,7 +2715,8 @@ int
sys_chflagsat(struct thread *td, struct chflagsat_args *uap)
{
- if ((uap->atflag & ~(AT_SYMLINK_NOFOLLOW | AT_BENEATH)) != 0)
+ if ((uap->atflag & ~(AT_SYMLINK_NOFOLLOW | AT_BENEATH |
+ AT_RESOLVE_BENEATH)) != 0)
return (EINVAL);
return (kern_chflagsat(td, uap->fd, uap->path, UIO_USERSPACE,
@@ -2743,7 +2749,7 @@ kern_chflagsat(struct thread *td, int fd, const char *path,
AUDIT_ARG_FFLAGS(flags);
NDINIT_ATRIGHTS(&nd, LOOKUP, at2cnpflags(atflag, AT_SYMLINK_NOFOLLOW |
- AT_BENEATH) | AUDITVNODE1, pathseg, path, fd,
+ AT_BENEATH | AT_RESOLVE_BENEATH) | AUDITVNODE1, pathseg, path, fd,
&cap_fchflags_rights, td);
if ((error = namei(&nd)) != 0)
return (error);
@@ -2838,7 +2844,8 @@ int
sys_fchmodat(struct thread *td, struct fchmodat_args *uap)
{
- if ((uap->flag & ~(AT_SYMLINK_NOFOLLOW | AT_BENEATH)) != 0)
+ if ((uap->flag & ~(AT_SYMLINK_NOFOLLOW | AT_BENEATH |
+ AT_RESOLVE_BENEATH)) != 0)
return (EINVAL);
return (kern_fchmodat(td, uap->fd, uap->path, UIO_USERSPACE,
@@ -2871,7 +2878,7 @@ kern_fchmodat(struct thread *td, int fd, const char *path,
AUDIT_ARG_MODE(mode);
NDINIT_ATRIGHTS(&nd, LOOKUP, at2cnpflags(flag, AT_SYMLINK_NOFOLLOW |
- AT_BENEATH) | AUDITVNODE1, pathseg, path, fd,
+ AT_BENEATH | AT_RESOLVE_BENEATH) | AUDITVNODE1, pathseg, path, fd,
&cap_fchmod_rights, td);
if ((error = namei(&nd)) != 0)
return (error);
@@ -2966,7 +2973,8 @@ int
sys_fchownat(struct thread *td, struct fchownat_args *uap)
{
- if ((uap->flag & ~(AT_SYMLINK_NOFOLLOW | AT_BENEATH)) != 0)
+ if ((uap->flag & ~(AT_SYMLINK_NOFOLLOW | AT_BENEATH |
+ AT_RESOLVE_BENEATH)) != 0)
return (EINVAL);
return (kern_fchownat(td, uap->fd, uap->path, UIO_USERSPACE, uap->uid,
@@ -2982,7 +2990,7 @@ kern_fchownat(struct thread *td, int fd, const char *path,
AUDIT_ARG_OWNER(uid, gid);
NDINIT_ATRIGHTS(&nd, LOOKUP, at2cnpflags(flag, AT_SYMLINK_NOFOLLOW |
- AT_BENEATH) | AUDITVNODE1, pathseg, path, fd,
+ AT_BENEATH | AT_RESOLVE_BENEATH) | AUDITVNODE1, pathseg, path, fd,
&cap_fchown_rights, td);
if ((error = namei(&nd)) != 0)
@@ -3334,13 +3342,14 @@ kern_utimensat(struct thread *td, int fd, const char *path,
struct timespec ts[2];
int error, flags;
- if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_BENEATH)) != 0)
+ if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_BENEATH |
+ AT_RESOLVE_BENEATH)) != 0)
return (EINVAL);
if ((error = getutimens(tptr, tptrseg, ts, &flags)) != 0)
return (error);
NDINIT_ATRIGHTS(&nd, LOOKUP, at2cnpflags(flag, AT_SYMLINK_NOFOLLOW |
- AT_BENEATH) | AUDITVNODE1,
+ AT_BENEATH | AT_RESOLVE_BENEATH) | AUDITVNODE1,
pathseg, path, fd, &cap_futimes_rights, td);
if ((error = namei(&nd)) != 0)
return (error);
@@ -3835,7 +3844,7 @@ kern_frmdirat(struct thread *td, int dfd, const char *path, int fd,
restart:
bwillwrite();
NDINIT_ATRIGHTS(&nd, DELETE, LOCKPARENT | LOCKLEAF | AUDITVNODE1 |
- at2cnpflags(flag, AT_BENEATH),
+ at2cnpflags(flag, AT_BENEATH | AT_RESOLVE_BENEATH),
pathseg, path, dfd, &cap_unlinkat_rights, td);
if ((error = namei(&nd)) != 0)
goto fdout;
@@ -4320,7 +4329,8 @@ int
sys_getfhat(struct thread *td, struct getfhat_args *uap)
{
- if ((uap->flags & ~(AT_SYMLINK_NOFOLLOW | AT_BENEATH)) != 0)
+ if ((uap->flags & ~(AT_SYMLINK_NOFOLLOW | AT_BENEATH |
+ AT_RESOLVE_BENEATH)) != 0)
return (EINVAL);
return (kern_getfhat(td, uap->flags, uap->fd, uap->path, UIO_USERSPACE,
uap->fhp));
@@ -4339,7 +4349,7 @@ kern_getfhat(struct thread *td, int flags, int fd, const char *path,
if (error != 0)
return (error);
NDINIT_AT(&nd, LOOKUP, at2cnpflags(flags, AT_SYMLINK_NOFOLLOW |
- AT_BENEATH) | LOCKLEAF | AUDITVNODE1,
+ AT_BENEATH | AT_RESOLVE_BENEATH) | LOCKLEAF | AUDITVNODE1,
pathseg, path, fd, td);
error = namei(&nd);
if (error != 0)
diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index ed859d61c0eb..171985dcb19a 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -200,6 +200,8 @@ open2nameif(int fmode, u_int vn_open_flags)
res = ISOPEN | LOCKLEAF;
if ((fmode & O_BENEATH) != 0)
res |= BENEATH;
+ if ((fmode & O_RESOLVE_BENEATH) != 0)
+ res |= RBENEATH;
if ((vn_open_flags & VN_OPEN_NOAUDIT) == 0)
res |= AUDITVNODE1;
if ((vn_open_flags & VN_OPEN_NOCAPCHECK) != 0)
diff --git a/sys/sys/fcntl.h b/sys/sys/fcntl.h
index a68425513971..2f424d173949 100644
--- a/sys/sys/fcntl.h
+++ b/sys/sys/fcntl.h
@@ -136,6 +136,9 @@ typedef __pid_t pid_t;
#if __BSD_VISIBLE
#define O_VERIFY 0x00200000 /* open only after verification */
#define O_BENEATH 0x00400000 /* Fail if not under cwd */
+#define O_RESOLVE_BENEATH 0x00800000 /* As O_BENEATH, but do not allow
+ resolve to walk out of cwd even to
+ return back */
#endif
/*
@@ -215,6 +218,9 @@ typedef __pid_t pid_t;
#define AT_SYMLINK_FOLLOW 0x0400 /* Follow symbolic link */
#define AT_REMOVEDIR 0x0800 /* Remove directory instead of file */
#define AT_BENEATH 0x1000 /* Fail if not under dirfd */
+#define AT_RESOLVE_BENEATH 0x2000 /* As AT_BENEATH, but do not allow
+ resolve to walk out of dirfd even
+ to return back */
#endif
/*
diff --git a/sys/sys/namei.h b/sys/sys/namei.h
index 07aad924bf4b..441c3f909f8b 100644
--- a/sys/sys/namei.h
+++ b/sys/sys/namei.h
@@ -133,7 +133,8 @@ int cache_fplookup(struct nameidata *ndp, enum cache_fpl_status *status,
#define BENEATH 0x0080 /* No escape from the start dir */
#define LOCKSHARED 0x0100 /* Shared lock leaf */
#define NOFOLLOW 0x0000 /* do not follow symbolic links (pseudo) */
-#define MODMASK 0x01fc /* mask of operational modifiers */
+#define RBENEATH 0x100000000ULL /* No escape, even tmp, from start dir */
+#define MODMASK 0xf000001fcULL /* mask of operational modifiers */
/*
* Namei parameter descriptors.
*