lsns: don't abort if /proc/self/ns/user is absent; probe other ns entries#3772
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karelzak merged 1 commit intoOct 6, 2025
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…ries In 7d5036f ("lsns: show namespaces only kept alive by open file descriptors"), I added code that calls stat(2) on /proc/self/ns/user and made lsns exit after reporting an error if the call failed. I assumed /proc/self/ns/user would be available on all platforms. As Axel Karjalainen reported (link below), that assumption was wrong: on some platforms, the file is absent. Exiting for this reason is undesirable. The stat(2) call is used to obtain the dev_t of the backing device of nsfs. However, /proc/self/ns/user is not the only source; calling stat(2) on other namespace files under /proc/self/ns yields the same dev_t. This change iterates over entries under /proc/self/ns and uses the first one whose stat(2) succeeds. Reported-by: Axel Karjalainen <axel@axka.fi> Link: util-linux#2902 (comment) Fixes: 7d5036f ("lsns: show namespaces only kept alive by open file descriptors") Signed-off-by: Masatake YAMATO <yamato@redhat.com>
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In 7d5036f ("lsns: show namespaces only kept alive by open file descriptors"), I added code that calls stat(2) on /proc/self/ns/user and made lsns exit after reporting an error if the call failed. I assumed /proc/self/ns/user would be available on all platforms.
As Axel Karjalainen reported (link below), that assumption was wrong: on some platforms, the file is absent. Exiting for this reason is undesirable.
The stat(2) call is used to obtain the dev_t of the backing device of nsfs. However, /proc/self/ns/user is not the only source; calling stat(2) on other namespace files under /proc/self/ns yields the same dev_t. This change iterates over entries under /proc/self/ns and uses the first one whose stat(2) succeeds.
Reported-by: Axel Karjalainen axel@axka.fi
Link: #2902 (comment)
Fixes: 7d5036f ("lsns: show namespaces only kept alive by open file descriptors")