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dfs cannot follow a symlink whose value is absolute (EINVAL since DAOS-19630), nor one whose relative value climbs more than one level with ".." (ENOTSUP): the first needs the process root, the second the ancestry of the link. In a non-leaf position the error came out of the parent walk in query_path() with no parent record, so the application saw EINVAL or ENOTSUP where the kernel resolves the path correctly through dfuse. Treat both errors from the parent walk, in query_path() and in resolve_dot_dot(), as "not handled by pil4dfs" so the libc function runs, and extend the leaf probe in need_kernel_to_resolve() to ENOTSUP. Drop root_symlink_escapes(): with the uniform EINVAL from dfs the root-level case is covered by the existing leaf probe. Add tests for an absolute directory link in a subdirectory and in the container root, each shadowed by an in-container copy of the target path, and for "..", "../../x" and "../../d/x" values as leaf and non-leaf components, inside and out of the container. Features: pil4dfs Signed-off-by: Mohamad Chaarawi <mohamad.chaarawi@hpe.com>
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Ticket title is 'pil4dfs: an absolute symlink in a non-leaf position of a path fails with EINVAL instead of being handed to the kernel' |
wangshilong
reviewed
Sep 20, 2026
| * that a chain such as python3 -> python -> /usr/bin/python3.x is caught as well. | ||
| */ | ||
| static bool | ||
| root_symlink_escapes(struct dfs_mt *dfs_mt, struct dcache_rec *parent, const char *item_name, |
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This seems to miss the O_NOFOLLOW case.
For a root symlink such as:
python -> /usr/bin/python3
open("python", O_RDONLY | O_NOFOLLOW) must fail with ELOOP . after removing root_symlink_escapes() , dfs_lookup_rel(..., O_NOFOLLOW, ...) may successfully return the symlink itself, so the error-based kernel fallback is not triggered.
Could we preserve the kernel fallback for this flag combination, and add a regression test that verifies O_NOFOLLOW returns ELOOP ?
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dfs cannot follow a symlink whose value is absolute (EINVAL since DAOS-19630), nor one whose relative value climbs more than one level with ".." (ENOTSUP): the first needs the process root, the second the ancestry of the link. In a non-leaf position the error came out of the parent walk in query_path() with no parent record, so the application saw EINVAL or ENOTSUP where the kernel resolves the path correctly through dfuse.
Treat both errors from the parent walk, in query_path() and in resolve_dot_dot(), as "not handled by pil4dfs" so the libc function runs, and extend the leaf probe in need_kernel_to_resolve() to ENOTSUP. Drop root_symlink_escapes(): with the uniform EINVAL from dfs the root-level case is covered by the existing leaf probe.
Add tests for an absolute directory link in a subdirectory and in the container root, each shadowed by an in-container copy of the target path, and for "..", "../../x" and "../../d/x" values as leaf and non-leaf components, inside and out of the container.
Features: pil4dfs
Steps for the author:
After all prior steps are complete: