Enum rsvg::ImplementationLimit

#[non_exhaustive]
pub enum ImplementationLimit {
    TooManyReferencedElements,
    TooManyLoadedElements,
    TooManyAttributes,
}

Errors for implementation-defined limits, to mitigate malicious SVG documents.

These get emitted as LoadingError::LimitExceeded or RenderingError::LimitExceeded. The limits are present to mitigate malicious SVG documents which may try to exhaust all available memory, or which would use large amounts of CPU time.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

TooManyReferencedElements

Document exceeded the maximum number of times that elements can be referenced through URL fragments.

This is a mitigation for malicious documents that attempt to consume exponential amounts of CPU time by creating millions of references to SVG elements. For example, the <use> and <pattern> elements allow referencing other elements, which can in turn reference other elements. This can be used to create documents which would require exponential amounts of CPU time to be rendered.

Librsvg deals with both cases by placing a limit on how many references will be resolved during the SVG rendering process, that is, how many url(#foo) will be resolved.

These malicious documents are similar to the XML billion laughs attack, but done with SVG’s referencing features.

See issues #323 and #515 for examples for the <use> and <pattern> elements, respectively.

TooManyLoadedElements

Document exceeded the maximum number of elements that can be loaded.

This is a mitigation for SVG files which create millions of elements in an attempt to exhaust memory. Librsvg does not’t allow loading more than a certain number of elements during the initial loading process.

TooManyAttributes

Document exceeded the number of attributes that can be attached to an element.

This is here because librsvg uses u16 to address attributes. It should be essentially impossible to actually hit this limit, because the number of attributes that the SVG standard ascribes meaning to are lower than this limit.

Trait Implementations

impl Clone for ImplementationLimit

fn clone(&self) -> ImplementationLimit

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ImplementationLimit

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for ImplementationLimit

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Copy for ImplementationLimit