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authorgVisor bot <gvisor-bot@google.com>2020-03-16 23:04:55 +0000
committergVisor bot <gvisor-bot@google.com>2020-03-16 23:04:55 +0000
commita30f38f72f1966a36eb138f2b5a5b5295012b58a (patch)
treeca36c55facc6d8418fa53c6cdd5872d3bfd2d20a
parentc78fcdc8af5ba8864c3161941115f5196a21a166 (diff)
parent2a6c4369be8d0522a1f439aa02bce0eb21d42ea2 (diff)
Merge release-20200219.0-184-g2a6c436 (automated)
-rwxr-xr-xpkg/sentry/syscalls/linux/vfs2/setstat.go15
-rwxr-xr-xpkg/sentry/vfs/file_description_impl_util.go5
-rwxr-xr-xpkg/sentry/vfs/permissions.go33
3 files changed, 50 insertions, 3 deletions
diff --git a/pkg/sentry/syscalls/linux/vfs2/setstat.go b/pkg/sentry/syscalls/linux/vfs2/setstat.go
index 9250659ff..136453ccc 100755
--- a/pkg/sentry/syscalls/linux/vfs2/setstat.go
+++ b/pkg/sentry/syscalls/linux/vfs2/setstat.go
@@ -173,12 +173,13 @@ func Truncate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
return 0, nil, err
}
- return 0, nil, setstatat(t, linux.AT_FDCWD, path, disallowEmptyPath, followFinalSymlink, &vfs.SetStatOptions{
+ err = setstatat(t, linux.AT_FDCWD, path, disallowEmptyPath, followFinalSymlink, &vfs.SetStatOptions{
Stat: linux.Statx{
Mask: linux.STATX_SIZE,
Size: uint64(length),
},
})
+ return 0, nil, handleSetSizeError(t, err)
}
// Ftruncate implements Linux syscall ftruncate(2).
@@ -196,12 +197,13 @@ func Ftruncate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sys
}
defer file.DecRef()
- return 0, nil, file.SetStat(t, vfs.SetStatOptions{
+ err := file.SetStat(t, vfs.SetStatOptions{
Stat: linux.Statx{
Mask: linux.STATX_SIZE,
Size: uint64(length),
},
})
+ return 0, nil, handleSetSizeError(t, err)
}
// Utime implements Linux syscall utime(2).
@@ -378,3 +380,12 @@ func setstatat(t *kernel.Task, dirfd int32, path fspath.Path, shouldAllowEmptyPa
FollowFinalSymlink: bool(shouldFollowFinalSymlink),
}, opts)
}
+
+func handleSetSizeError(t *kernel.Task, err error) error {
+ if err == syserror.ErrExceedsFileSizeLimit {
+ // Convert error to EFBIG and send a SIGXFSZ per setrlimit(2).
+ t.SendSignal(kernel.SignalInfoNoInfo(linux.SIGXFSZ, t, t))
+ return syserror.EFBIG
+ }
+ return err
+}
diff --git a/pkg/sentry/vfs/file_description_impl_util.go b/pkg/sentry/vfs/file_description_impl_util.go
index 45191d1c3..d45e602ce 100755
--- a/pkg/sentry/vfs/file_description_impl_util.go
+++ b/pkg/sentry/vfs/file_description_impl_util.go
@@ -339,6 +339,11 @@ func (fd *DynamicBytesFileDescriptionImpl) pwriteLocked(ctx context.Context, src
if opts.Flags&^(linux.RWF_HIPRI|linux.RWF_DSYNC|linux.RWF_SYNC) != 0 {
return 0, syserror.EOPNOTSUPP
}
+ limit, err := CheckLimit(ctx, offset, src.NumBytes())
+ if err != nil {
+ return 0, err
+ }
+ src = src.TakeFirst64(limit)
writable, ok := fd.data.(WritableDynamicBytesSource)
if !ok {
diff --git a/pkg/sentry/vfs/permissions.go b/pkg/sentry/vfs/permissions.go
index 8e250998a..2c8f23f55 100755
--- a/pkg/sentry/vfs/permissions.go
+++ b/pkg/sentry/vfs/permissions.go
@@ -15,8 +15,12 @@
package vfs
import (
+ "math"
+
"gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+ "gvisor.dev/gvisor/pkg/sentry/limits"
"gvisor.dev/gvisor/pkg/syserror"
)
@@ -147,7 +151,16 @@ func MayWriteFileWithOpenFlags(flags uint32) bool {
// CheckSetStat checks that creds has permission to change the metadata of a
// file with the given permissions, UID, and GID as specified by stat, subject
// to the rules of Linux's fs/attr.c:setattr_prepare().
-func CheckSetStat(creds *auth.Credentials, stat *linux.Statx, mode uint16, kuid auth.KUID, kgid auth.KGID) error {
+func CheckSetStat(ctx context.Context, creds *auth.Credentials, stat *linux.Statx, mode uint16, kuid auth.KUID, kgid auth.KGID) error {
+ if stat.Mask&linux.STATX_SIZE != 0 {
+ limit, err := CheckLimit(ctx, 0, int64(stat.Size))
+ if err != nil {
+ return err
+ }
+ if limit < int64(stat.Size) {
+ return syserror.ErrExceedsFileSizeLimit
+ }
+ }
if stat.Mask&linux.STATX_MODE != 0 {
if !CanActAsOwner(creds, kuid) {
return syserror.EPERM
@@ -205,3 +218,21 @@ func CanActAsOwner(creds *auth.Credentials, kuid auth.KUID) bool {
func HasCapabilityOnFile(creds *auth.Credentials, cp linux.Capability, kuid auth.KUID, kgid auth.KGID) bool {
return creds.HasCapability(cp) && creds.UserNamespace.MapFromKUID(kuid).Ok() && creds.UserNamespace.MapFromKGID(kgid).Ok()
}
+
+// CheckLimit enforces file size rlimits. It returns error if the write
+// operation must not proceed. Otherwise it returns the max length allowed to
+// without violating the limit.
+func CheckLimit(ctx context.Context, offset, size int64) (int64, error) {
+ fileSizeLimit := limits.FromContext(ctx).Get(limits.FileSize).Cur
+ if fileSizeLimit > math.MaxInt64 {
+ return size, nil
+ }
+ if offset >= int64(fileSizeLimit) {
+ return 0, syserror.ErrExceedsFileSizeLimit
+ }
+ remaining := int64(fileSizeLimit) - offset
+ if remaining < size {
+ return remaining, nil
+ }
+ return size, nil
+}