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:
“When kindness has left people, even for a few moments, we become afraid of them as if their reason had left them. When it has left a place where we have always found it, it is like shipwreck; we drop from security into something malevolent and bottomless.”
—Willa Cather (1876–1947)
“Modern children were considerably less innocent than parents and the larger society supposed, and postmodern children are less competent than their parents and the society as a whole would like to believe. . . . The perception of childhood competence has shifted much of the responsibility for child protection and security from parents and society to children themselves.”
—David Elkind (20th century)
“... most Southerners of my parents’ era were raised to feel that it wasn’t respectable to be rich. We felt that all patriotic Southerners had lost everything in defense of the South, and sufficient time hadn’t elapsed for respectable rebuilding of financial security in a war- impoverished region.”
—Sarah Patton Boyle, U.S. civil rights activist and author. The Desegregated Heart, part 1, ch. 1 (1962)