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Add sudo for file access permissions

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Add sudo to commands in Chapter 8 for example module interaction.

The "myvariables" in the module are set with 0660 permissions
via __ATTR(), preventing direct user access.

Options to fix this:
1. Instruct users to use 'sudo' to read/write files.
2. Relax the permission settings to 0666.

This commit adopts the sudo method to maintain security constraints.
This commit is contained in:
HJ Pao 2024-07-03 00:50:50 +08:00
parent 1d3943a72b
commit be16ad6710
1 changed files with 3 additions and 3 deletions
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6
lkmpg.tex
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@ -1347,14 +1347,14 @@ sudo lsmod | grep hello_sysfs
What is the current value of \cpp|myvariable| ?
\begin{codebash}
cat /sys/kernel/mymodule/myvariable
sudo cat /sys/kernel/mymodule/myvariable
\end{codebash}
Set the value of \cpp|myvariable| and check that it changed.
\begin{codebash}
echo "32" > /sys/kernel/mymodule/myvariable
cat /sys/kernel/mymodule/myvariable
echo "32" | sudo tee /sys/kernel/mymodule/myvariable
sudo cat /sys/kernel/mymodule/myvariable
\end{codebash}
Finally, remove the test module: