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Fix invalid ATIME mask when clearing recursive mount options #5096

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Fix invalid ATIME mask when clearing recursive mount options #5096

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9fd997b
specconv: fix recursive mount access-time clearing
arnavgogia20 Feb 3, 2026
aa89145
tests: add regression test for recursive mount ATIME clearing
arnavgogia20 Feb 3, 2026
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10 changes: 10 additions & 0 deletions libcontainer/specconv/spec_linux.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1161,6 +1161,16 @@ func parseMountOptions(options []string) *configs.Mount {
if f.clear {
recAttrClr |= f.flag
recAttrSet &= ^f.flag
// The kernel's mount_setattr(2) requires that if any bit of the
// MOUNT_ATTR__ATIME mask is changed, the full mask must be present in
// attr_clr. Partial masks result in EINVAL.
//
// We intentionally use unix.MOUNT_ATTR__ATIME (which should be 0x70)
// instead of constructing it from flags, because strict adherence
// to the kernel's definition of the mask is required.
if f.flag&unix.MOUNT_ATTR__ATIME == f.flag {
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@lifubang lifubang Feb 3, 2026

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Please look at the next else block — it contains the same code. Consider combining these two branches.
See #5098.

recAttrClr |= unix.MOUNT_ATTR__ATIME
}
} else {
recAttrSet |= f.flag
recAttrClr &= ^f.flag
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34 changes: 34 additions & 0 deletions libcontainer/specconv/spec_linux_test.go
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Expand Up @@ -1017,3 +1017,37 @@ func TestCreateNetDevices(t *testing.T) {
})
}
}

func TestParseMountOptionsRecursiveAtime(t *testing.T) {
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@lifubang lifubang Feb 3, 2026

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A unit test isn’t needed here, but an integration test is required.
Also see #5098

// These options correspond to clears in recAttrFlags, triggering the 'clear' path.
// We expect recAttrClr to contain the full MOUNT_ATTR__ATIME mask.
const mountAttrAtime = unix.MOUNT_ATTR__ATIME

testCases := []struct {
opt string
mask uint64
}{
{"ratime", mountAttrAtime},
{"rnostrictatime", mountAttrAtime},
{"rnorelatime", mountAttrAtime},
}

for _, tc := range testCases {
m := parseMountOptions([]string{tc.opt})
if m.RecAttr == nil {
t.Errorf("option %s: expected RecAttr to be set", tc.opt)
continue
}

// Check if the attr_clr has the full mask set
if m.RecAttr.Attr_clr&tc.mask != tc.mask {
t.Errorf("option %s: expected attr_clr (0x%x) to contain full ATIME mask (0x%x)",
tc.opt, m.RecAttr.Attr_clr, tc.mask)
}

// Sanity check: Attr_set should be 0 for these clear-only options
if m.RecAttr.Attr_set != 0 {
t.Errorf("option %s: expected attr_set to be 0, got 0x%x", tc.opt, m.RecAttr.Attr_set)
}
}
}