Tidy handling of privileged operation fds #666
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…kets Both sockets in this socket pair are technically bidirectional, but we're using them in a way that is close enough to unidirectional that using these symbolic constants is clearer than magic numbers. We send multi-byte requests into the write end, and read those requests from the read end (even though we also send a 1-byte reply to each request into the "read" end, and read it from the "write" end). Signed-off-by: Simon McVittie <smcv@collabora.com>
This is inspired by g_steal_fd() in GLib, and lets us make it explicit that ownership of a fd is being moved, similar to steal_pointer(). Signed-off-by: Simon McVittie <smcv@collabora.com>
Setting the members of privsep_sockets[] to -1 when they have been closed or had their ownership transferred is clearer than leaving behind dangling references. Signed-off-by: Simon McVittie <smcv@collabora.com>
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This avoids leaving dangling references to fds that no longer exist, clarifying ownership. This commit does not cover the socket pairs used to transfer the pid of a descendant process (see containers#665 for that) and privilege-separated operations (see containers#666). Signed-off-by: Simon McVittie <smcv@collabora.com>
This was referenced Oct 30, 2024
... is not (currently) something that |
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Similar to #665, but for the socket pair that communicates privileged operations between the temporary unprivileged child and the privileged parent when we are setuid root.
Use PIPE_READ_END, PIPE_WRITE_END to clarify use of privileged op sockets
Both sockets in this socket pair are technically bidirectional, but
we're using them in a way that is close enough to unidirectional that
using these symbolic constants is clearer than magic numbers.
We send multi-byte requests into the write end, and read those requests
from the read end (even though we also send a 1-byte reply to each request
into the "read" end, and read it from the "write" end).
utils: Add steal_fd()
This is inspired by g_steal_fd() in GLib, and lets us make it explicit
that ownership of a fd is being moved, similar to steal_pointer().
Clarify ownership of privileged op sockets
Setting the members of privsep_sockets[] to -1 when they have been
closed or had their ownership transferred is clearer than leaving behind
dangling references.
cc @refi64