Security
On Unix, a setuid program is given an environment chosen by its caller, but it runs with different authority from its caller. The dynamic linker will usually load code from locations specified by the environment variables LD_LIBRARY_PATH and LD_PRELOAD and run it with the process's authority. If a setuid program did this, it would be insecure, because its caller could get it to run arbitrary code and hence misuse its authority. For this reason, libc unsets these environment variables at startup in a setuid process. setuid programs usually unset unknown environment variables and check others or set them to reasonable values.
Read more about this topic: Environment Variable
Famous quotes containing the word security:
“A well-regulated militia being necessary to the security of a free State, the right of the people to keep and bear arms shall not be infringed.”
—U.S. Constitution, Second Amendment.
“The reins of government have been so long slackened, that I fear the people will not quietly submit to those restraints which are necessary for the peace and security of the community.”
—Abigail Adams (1744–1818)
“The three great ends which a statesman ought to propose to himself in the government of a nation, are,—1. Security to possessors; 2. Facility to acquirers; and, 3. Hope to all.”
—Samuel Taylor Coleridge (1772–1834)